Medical and heaithcare textiles
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The Textile Institute and Woodhead Publishing The Textile Institute is a unique organisation in textiles, clothing and footwear. Incorporated in England by a Royal Charter granted in 1925, the Institute has individual and corporate members in over 90countries. The aim of the Institute is to facilitate learning, recognise achievement, reward excellence and disseminate information within the global textiles, clothing and footwear industries. Historically,The Textile Institute has publishedbooks of interest to its members and the textile industry. To maintain this policy, the Institute has entered into partnership with Woodhead Publishing Limited to ensure that Institute members and the textile industry continue to have access to high calibm titles on textile science and technology. Most Woodhead titles on textiles are now published in collaboration with The Textile Institute. Through this arrangement, the Institute provides an Editorial Board which advises Woodhead on appropriate titles for future publication and suggests possible editors and authors for these books. Each book published under this arrangement carries the Institute’s logo. Woodhead books published in collaboration with The Textile Institute are offered to Textile Institute members at a substantial discount. These books, together with those published by The Textile Institute that are still in print, are offered on the Woodhead web site at: www.woodheadpublishing.com. Textile Institute books still in print are also available directly from the Institute’s website at: www.textileinstitutebooks.com. A list of Woodhead books on textile science and technology,most of which have been published in collaboration with The Textile Institute, can be found towards the end of the contents pages.
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Woodhead Publishing Series in Textiles: Number 75
Medical and healt hcare textiles Edited by S. C. h a n d , J. F. Kennedy, M. Miraftab and S. Rajendran
TheXxtile Institute
CRC Press Boca Raton Boston New York Washington, DC
W O O D H E A DP U B L I S H I N G Oxford 0 W o o d h e a d Publishing Limited, 201 0
Cambridge
LIMITED New Delhi
published by Woodhead Publishiag Limited in assoCiation with The Textile Jnstitute Woodhead Publislung Limited,Abington Hall, GrardaPark,Great Abington Cambridge CB216Ay UK www.wOodheadpublishiug.com
Woodhead Publishing IndiaPrivate Limited, G-2, Vardiun House,7/28 Ansari Road,Daryagazj, New Delhi - 110002, India www.woodheadpublisbgindia.com Published in North America by CRC Press LLC, 6000 Broken Sound Parkway, NW, Suite 300, Boca Raton, FL 33487, USA
First published 2010, Woodhead Publishing Limited and CRC Press LLC Q woodhead Publishlug Limitd 2010 The authors have asserted their moral rights.
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CONTENTS WoodheadPublishing Series in Textiles Preface
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PART I INFECTION CONTROL AND BARRIER MATERIALS Infedion control and barrier materirrls: an overview S Rajendran, University of Bolton, UK - Introduction - Wound infection - Hospital protective materials - Bibliography
3
Antimicrobial properties of silvercontaining chitosan fibers Y Qin and C Zhu, %Biochemical Materials Research and Development Cenlre, China - Introduction - Experimental - Results and discussion - Conclusions - References
7
Copperimpregnated anthkmbial textiles: an innovative weapon to fight infeetion G Borkow, A Felix and J Gabbay, Cupron Inc, USA - Copper as a biocide - Incorporationof copper oxide into natural and synthetic fibres - Biocidal properties of fabrics containing copper oxide - Clinical studies - Discussion - References
14
A review of the role of microwaves in the destruction of pathogenic bacteria A S Lamb and E Siores, University of Bolton, UK - Microwave interactions with materials - Fixed ftequency microwave interactions with bacteria - Work carried out at the University of Bolton Flowcytometry - Concluding remarks - References
23
Antimicrobial bioactive band-aids with prolonged and controlled action P Shndric, L Simovic, M Kostic, A Medovic, KMilosevic and S Dimitrijevic, University of Belgrade, Serbia - Introduction - Experimental - Experimental results and discussion - Conclusion - References
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Comparison of antimicrobial textile treatments
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E Smith, J T Williams, S E Walsh and P Painter, De Monij4orf University, UK - Introduction
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Materials and methods Results and discussion Conclusions References
Evaluation of plasma-deposited anti-adhedive and anti-bacterial coatings on m e d i d textiles A J Paul, F Bretagnol, G Buyle, C Colin, 0 Lepanc and H Rauscher, C S M Ltd, UK Plasma treatment of textiles - X-ray photoelectron spectroscopy (XPS) - Time-of-flight secondary ion mass spectrometry (ToFSIMS) - References
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Controlling the spread of infectionsin hospital wards by the use of antimicrobials on medical textiles and surfaces W C White,AEGIS Environmental Management, USA.R. BellJield, Carrington Career and Workwear Ltd, U .J Ellis, Devan-PPT Chemicals Ltd UK and Ir P Vandendaele, Devan ChemicalsW,Belgium - Introduction Microorganisms - Antimicrobials - Organohctional silane antimicrobial technology - Verificationtechniques and safety profile - Potentialuses - Hospital blankets - Nonwoven surgical drapes - Wound care silk dressings - carpeting
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Uniforms - Siliconerubber
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Case study: the Arthur G. James Cancer Center Hospital and Research Institute
- summary
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References
Inherenth antimicrobial alchite fibres developed for wound care applications MMiraftab, C Iwu, C Okoro and G Smart, Universityof Bolton, UK - Introduction - Productionmethodology - Results and discussions - Conclusions - References
Antimicrobialtextilea for health and hygiene applications based on eeo-friendly natural products M Joshi, R Purwar and S W Ali, Indian Institute of Technology, India and S R a j e d a n , Universityof Bolton, UK - Introduction vi
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Natural antimicrobial agents for textile substrates Antimicrobial finishing of textiles based on neem extract Conclusion References
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Investigation of the filtration properties of medical masks MAkulin, I Usta, D Kocak and M S Ozen, Marmara Universiw, Turkey - Introduction - Materials and method - Results Conclusion - References
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Lint release charncteristia of nonwoven wipes V K Kothari and R Loganathan, Indian Institute of Technology, India - Introduction - Design of measurement apparatus Materials and methods - Results and discussion - Conclusions
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Development of antimicrobialpolyester uskg neem extract S Wazed Ali, B Gupta and M Joshi, Indian Institute of Technology, India - Introduction - Materials - Methods - Results and discussion - Conclusion - References Fixation of cationic antibacterialproducts before dyeing: a more ecological process R V Vieira, J G Santos, G A4 B Soares and J I N R Comes, University of Minho, Portugal - Introduction - Experimental
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Results and discussion
Conclusions
- References
Preliminary studies into wash-fast antimicrobial treatments of polyester 0 H a w k NAllen, G C Lees, H Rowe and J Verran, Manchester Mefropolitan University, UK - Introduction - Background - Methodology - Results - Futurework - References 0 Woodhead Publishing Limited, 201 0
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Emyme-catalysedcoupling of functionalantioxidan@onto protein fibres S JUTand G MGuebitz, Technical University of Graz, Austria and V Kokol, University of Maribor, Slovenia - InttOdUCtiOn - Materials and methods - Results and discussion - Conclusions References
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PART II HEALTHCARE AND HYGIENE PRODUCTS 137
Healthcare and hygiene products: an overview
S C Anand, University of Bolton, UK
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Introduction Recentadvances References
Cellulosic materials for odor and pH control J K Dutkiewicz, Buckeye TechnologiesInc, USA Introduction - Experimentalmodel - Ammonia emission studies - FreshcomfortTMtechnology - Conclusions - References
140
Development of a high-absorbent sanitary napkin A Das, V K Kothari and S Makhva, Indian Institute of Technology, India - Introduction - Experimental Results and discussions - Conclusions - References
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Retention of anionic rurlactmt followinggarment handering and its potential effect on dermatitis suffererr H D Rowe, Manchester Metropolitan University, UK - Introduction - Experimental - Results - Discussion - Conclusions - References Preparation of protective disposable hygiene fabric8 for medical appIications MMontazer, Amirkabir University of Technology,Iran, F Rangchi, TehranAzad University,Iran and F Siavoshi, Tehran Universi& Iran introduction Experimental
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Conclusions References
Development of surgical clothing from bamboo fibres K Ramachandralu, PSG College of Technologv, India - Introduction - Materials and methods - Results and discussions - Conclusions References
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Thermal characterizationand mechanical properties of PLA y a m A MManich, MMarti and R MSauri, Spanish Councilfor Scientijk Research, Spain, D Cayuela, Technical University of Catalonia, Spain and M USS+ Universidade da Beira Interior, Portugal - Introduction - Materials - Methods - Results - Discussion and conclusions - References
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PART IIIWOUND CARE MATERIALS Wound care materials: an overview M Mirajlab, University of Bolton, UK - Introduction - Wounds: natural healing mechanisms versus wound care materials - Review of papers on wound w e materials - References
193
Controlled drug release from nanofibrona polyester materials M J Bide, University of Rhode Island, USA, M D Phaneuf and T M Phaneuf; BioSurfaces, USA and P JBrown, Clemson University, USA - Introduction - Experimental - Results - Conclusions - References
198
Development of odour (volatile molecule) adsorbent materials for healthcare G Lee, S C Anand and S Rajendran, Universityof Bolton, UK and I Walker, Lantor (VK)Ltd, UK - Introduction - Odour adsorbent materials - Experimental work - Results - Conclusions - References
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Development of a decision support system for determination of suitable dressings for wounds K G Karthick and M Miraftab, Universityof Bolton, UK and JAshton, Bolton Primary Care Trust, UK Introduction - Research amongst nursing staff - The need for a decision support system - Expert systems in medicine - Decision support system for wound dressing selection - Conclusion - References
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Treatment of cotton fabria with ethyl cellulose dcrocapsulea R Badulescu, University of Ploiesti, Romania and B Voncina, V Vivod and D Jausovec, University of Maribor, Slovenia - Introduction - Experimental - Results and discussion - Conclusions - References
226
Measuring interface pressure in compression garments for barns patients E Maklewska, A Navrocki, K Kowalski and W Tmowski, Institute of Knitting Technology and Techniques, Poland Introduction - Investigationmethods - Testmaterial - Test results and discussion - Conclusions - References
236
Psyllium: current and future applications R Mmood and MMiraftab, Universityof Bolton, UK
244
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- Introduction
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The psyllium plant
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Physiochemical properties of psyllium Recent medical application of psyllium Other applications of psyllium Conclusions References
- History - Traditional food applications -
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PART IV BANDAGING AND PRESSURE GARMENTS Bandaging and pressure garments: an overview S C A& University of Bolton, UK - Introduction - Causes of venous disorders x
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- Factors which determine sub-bandage pressure
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Classification of compressionbandages Recent advances in compression therapy Single-layer compressionbandages References
Biomaterials with controlled elasticity for post-operationrecovery M Carmen and E Alexandra, The National Institutefor Textile and Leather, Romania - Introduction - Testing cytotoxicity and sensitizing potential - Testing methods - Results: sensitizing and irritation potential - Conclusions - References A study of the pressure profde of compression bandager, and compression garments for treatment of venous leg ulcers MSikkq S Ghosh andA Mukhopadlyqy, National Institute of Technology,India - Introduction - Materials - Method - Results and discussion - Conclusions - References Development of t h r e e d mensional structures for singlelayer compression therapy S Rajendran and S C Anand, Universityof Bolton, UK - Introduction - The treatment of venous leg ulcers Compression systems - Problems with current bandages - 3D compression bandages - Materials and methods - Results and discussion - summary - References
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Intermittent pneumatic compressionand bandaging: the effects of external pressure applied over bandaging S Rithalia and A4 Leyden, University of Salford, UK - Introduction - Methods and materials - Results - Conclusions - References Physiological effects of Lycra@pressure garments on children with cerebd palsy JAttard Royal National Orthopaedic Hospital, UK and S Rithalia, Universityof Salford, UK - Introduction 0 Woodhead Publishing Limited, 201 0
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Cerebralpalsy ~ynami~ c ycra@ pressure garments Aims and objectives of study Method Results Discussion Conclusions References
Empirical modelling of elastic properties of pressure garments for healthcare S Pereira, S C Anand and S Rajendran, University of Bolton, UK and C Wood, BaltexLtd, UK - Introduction Experimental Results and discussion - Conclusions References
309
Investigation of elastic properties of multhxid warp knitted bandages MAkalin, D KoFak, S I Mistik and M Uzun, Marmara University, Turkey Introduction - Materials and methods Results - Conclusions - References
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PART V IMPLANTABLE MATERIALS Implantable materials: an overview S Rqjendran, University of Bolton, UK - Introduction - vasculargrafts - Kneeimplants - Meshgrafts - SCafTOlds - Bibliography
329
Designing vena cava 6ltera with textile structure9 J Yoon and M W King, North Carolina State University, USA and E Johnson, Crux Biomedical Inc, USA - Introduction Current filters for embolic protection - Discussion - Conclusion - References
334
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Application of polyvinylidenefluoride (PVDF) as a biomaterial in medical textiles S Houis and T Gries, R WTH Aachen University, Germany, E M Engelhardt and F Wurm, Ecole Polytechnique Fkdkrale de Lausanne, Switzerland Introduction - Stateoftheart - Production of medical textiles - Projects using PVDF for medical applications - Conclusion - References
342
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Textile scaffolds for tissue engineering - near future or just vision? D Aibibu, S Houis, M S Harwoko and T Gries, RWTH Aachen Universiv, Germany - Introduction - Materials - Results - Discussion - References
353
Visible invisibility: contamination-aware textile surface8 A Toomey, Royal College of Art, UK - Introduction - Infection risks - Infection control - ‘Visible invisibility’ contaminationaware surfaces Conclusion - References
357
Textile medical produ- for the stabilizationof the thoracic wall E Alexandra and M Carmen, The National htitutefor Textile and Leather, Romania and N Alexandru, VictorBabes Medical and Pharmaceutical University,Romania - Introduction - Experimental - Clinical experiments - Results - Conclusions - References
368
Predicting the fatigue performance of endovascular prostheses H Zhao, L Wang,Y Li andXLiu, Donghua University, China and M W King, North Carolina State University, USA Introduction - Experimental - Results and discussion - Conclusions - References
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Integrationand embedding of vital signa 8emom and other devices into tatiles
381
M JAbreu, H Carvalho,A Catarino and A Rocha, Universidade do Mnho, Portugal
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Introduction
- Review of the state of the art
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Overview of general principles Experimental,results and discussions Conclusions References
PART MMEDICAL DEVICES Textilebased medical devices: an overview J F Kennedy and C J Knill, ChembiotechLaboratories - Institute of Advanced Science and Technology, UK - What is a medical device? - Medical textiles and their applications - Biomaterials used in medical textiles - References
Design and release rates of a novel biodegradable slow-release implant for the prevention of paediatric dental caries G J Dunn and A F Fotheringham, Heriot-Watt University, UK
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Introduction
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Results and discussion
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References
391
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- Materials and methods - Conclusions Maternity support garment for the relief of lower back pain S Ho, W Yu,T Lao, D Chow, J Chung and Y Li, The Hong Kong Polytechnic University, Hong Kong - Introduction - Studyaims Study objectives
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404
summary References
Self-powered medical devicea for vibration suppression
415
L MSwallow, E Sores, D Dodcis and J K Luo, University of Bolton, UK
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Introduction Piezoelectric materials Power harvesting Vibration suppression Device overview
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Discussion
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References
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- Results - Futurework
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Gas plasma treatment of polypropylene (PP) dental tape J M Warren,R R Mather and D Robson, Heriot-Wan University UK and A Neville, University of Lee&, UK - Introduction - Experimental - Surfme characteristics of plasma treated tape - PP tapes as dental flosses - References
423
Investigatingh e t a r e mechanisms of some non-absorbable sutures in Viva A S Hockenberger and E Karaca, Ul&g Universily, Turkey - Introduction Experimental - Results and discussion - Conclusion - References
430
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Wearable microwave radiometry device for early detection of sub-tissue oncological imperfections T Shah and E Siores, University of Bolton, UK - Introduction - Main types of breast cancer - Detection of breast cancer - Microwave radiometry - Microwave radiometer design and testing - Device integration with fabric - Conclusions - References Investigation of differences in Caprosyn, Biosyn, Polysorb, Novafil and surgipm sutures A D Erem and E Onder, Istanbul Technical University, Turkey and H H Erem, GATA Hayhrpasa Training Hospital, Turkey - Introduction - Materials - Method - Results Conclusions - References
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PART W SMART MATERIALS AND TECHNOLOGIES
Smart materials and technologies: an overview MMiraBab, University of Bolton, UK - Introduction Review of papers on smart materials - References
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Smart testilea embedded with optical fibre sensors for health monitoring
of patienta F Pirotte, Centexbel, Belgium, A Depre, Elasta, Belgium, R Shishoo, Shishoo Consulting, Sweden, J De Jonckheere, ITM France and A Grillet, Multitel, Belgium - Introduction - OFSETH research project - Preliminary results - Conclusions - References Integrating contactlesssensors for stress level monitoringinto clothing using conductive threads C Rotsch, D Zschena'erlein and U Mohring, TlTv Greiz, Germany - Introduction - Conductivethread materials for the integrationof textile senson and actuators - References Desiguing compressive stmtch garments for improved comfort and fit P A Watkins,London College of Fashion, UK - Introduction - Garment pressure research literature - Traditional pattern design and mobility - Proximal fit pattern design - summary - References
Blun hazard potential, pre-ignition and post-ignition thermal properties of textiles A W Kolhatkar, J D Instifute of Engineering and Technology, India and P C Patel, M S University of Baroda, India
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Introduction
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Results and discussion conclusions References
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477
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- Materials and methods
Assessing the performance of alternating pressure ah mattresses (APAMa) S V S Rithalia and G H Heath, University of Salfrd, UK
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Introduction Methods and materials Results Discussion References
Smart textiles with slow-release ceramides for sensitive skin M Marti, R Ramirez and L Coderch, IIQAB (CSIC), Spain and M Lis, J A Navarro and J Valldeperas,NTEXTER (UPC), Spain Introduction - Ceramides fiom wool - Liposome formation and evaluation
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Application of IWL-ceramideliposomes
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Conclusions
- Microencapsulation - References PART Mn INDUSTRY STANDARJJS AND REGULATIONS Directives,regnlatio~and standardsfor the medical device industry: an overview C J Knill and J F Kennedy, Chembiotech Laboratories - Institute of Advanced Science and Technology, UK - Medical devices in the EU - Medicines and Healthcare Products Regulatory Agency - CEmarking - Safety/quality standard monitoring - Biocompatibilitytesting - TheDrugTariff - References
519
Recent changm to the UK Drug Tariff for appliances listed in Part M G J Collyer, Sumed International Ltd UK - Introduction - History to the reimbursement of appliances - The Gershon Review 2004 - The Supply Cbain Excellence Programme - Conclusions - References
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Recycling textile and plastic waste Edited by A. R. Horroch
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New fibers Second edition T.Hongu and G. 0.Phillips
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Coated and laminated textilea
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types of dyes Edited by M Clark 117 Handbook of textile and industrial dyeing. Volume 2: Applications of dyes
Edited by M CIark 118 Handbook of natural fib-.
Volume 1: Typea, properties and factors affecting
breeding and cultivation Edited by R Kozlowski 1 19 Handbook of natural fibres. Volume 2: Processing and applications Edited by R Kozlowski
120 Functional textiles for improved performance, protection and health
Edited by N.Pan and G.Sun 121 Computer technology for textiles and apparel
Edited by Jmlian Hu 122 Advances in military textilea and personal equipment Edited by E. Sparks 123 Specialist yarn, woven and fabric structure: Developmenta and applications Edited by R H Gong
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Healthcare and medical textiles play a significant role within the technical textiles sector. The increased awareness of the need to enhance the quality of life of people has significantly contributed to the high consumption and sustained growth of medical textiles over the past decade. The importance of medical textiles is reflected in the fact that it already accounts for over 10% of the technical textiles market. It is interesting to note that the consumption of medical textiles in countries like India and China has grown remarkably in the recent past and is expected to grow significantly in Africa and Middle East in the next decade. There is a considerable market potential for advanced wound dressings with a forecast annual growth of between 10% and 15% in 2012. A number of medical textiles products that include wound dressings and bandages are now classified as ‘medical devices’ by European legislation with the need to carry CE marking. This indicates their importance and the fact that they occupy a unique position within medicine and surgery. As an example, compression therapy using compression bandages is considered as the ‘gold standard’ for managing venous ulceration. Until now there has been no alternative medication or surgical procedure to cure the disease. The University of Bolton has gained worldwide recognition in medical textiles research, product development and knowledge transfer. With regard to knowledge transfer activities, the University is unique in organising international conferences focusing only on healthcare and medical textiles as well as publishing interdisciplinary statesf-the art books exclusively for medical professionals, medical device manufacturers, textile scientists and researchers. The University has so far hosted international MEDTEX conferences in 1996, 1999, 2003 and 2007 at Bolton and joint international conferences (FiberMed) in collaboration with Tampere University of Technology in Finland in 2000 and 2006. In the past books such as Developments in medical textiles, Medical textiles 96: Medical textiles 99 ’, Medical textiles and biomaterials for healthcare and Advanced textiles for wound care, published with Woodhead Publishing Limited,have attracted a great deal of attention from readers. This book, Medical and healthcare textiles, comprises of a selection of papers presented and discussed during MEDTEX 07. There are eight parts to the book, each of them containing an introductory overview. Part I contains fifteen papers and addresses the risk of infection, cross-infection and infection control. The application of textile materials and products to prevent and control infection is extensively discussed. Six papers in Part II demonstrate the significance of textile products in healthcax and hygiene applications for use not only in hospitals but also in other environments where hygiene is essential. Advanced wound dressings such as drug delivery dressings and odour-adsorption dressings are critically discussed in Part 111which also comprises six papers. Part IV is divided into seven papers and highlights multilayer and single-layer compression therapy for venous leg ulcer patients. Recent developments and application of hi-tech implantable medical devices are discussed in the seven papers which constitute Part V. Part VI consists of seven papers which emphasise the role of textiles in medical devices in various applications including dentistry and oncology. The integration of novel sensors in textile products for the application of wearable health monitoring products and research related to smart materials are discussed in Part VII 0 Woodhead Publishing Limited, 2010 xxvii
which is made up of 6 papers. A special paper in Part WI describes the role of the Drug Tariff regulatory body in the UK as well as the recent chmges affectingthe medical devices market. The editors are deeply indebted to all the authors in this publication. Their contributions are invaluable for the further development of the medical textiles sector around the world. We are grateful to all the companies who sponsored and supported MEDTEX 07. The assistance provided by Mrs Anita Taylor during the preparation of the book is gratefully acknowledged. Last, but not the least, we are thankfd to Woodhead Publishing Limited in Cambridge for their continued support over a number of years in publishing specialist books relating to medical textiles. Prof S. C. Anaud MBE DrM.MiraRab Dr S. Rajendran Institute for Materials Research and Innovation The University of Bolton, UK
Prof J. F. Kennedy Chembiotech Laboratories Institute of Advanced Science and Technology, UK
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PART I
INFECTION CONTROL AND BARRIER MATERIALS
INFECTION CONTROL AND BARRIER MATERIALS- AN OVERVIEW S.Rajendran Institute for Materials Research and Innovation University of Bolton, Bolton BL3 5AB, UK
INTRODUCTION With the arrival of high risk microorganisms such as (Methkillin-resistant stuphyiococcus uureus) MRSA and Swine flue (HlN1 virus), infection control is a serious problem, especially in hospital environments. Hospital-acquired infections cost the National Health Service (NHS) in the UK E l billion and contribute to the death of an estimated 5000 patients a year. The Department of Health in the UK estimates that such infections can cost an extra fA000d10000 per patient. Controlling wound infixtion in hospitals is a day-to-day problem for healthcare personnel despite the precautionary measures taken to avoid them. Both acute and chronic wounds are vulnerable to bacterial infection. Highly-exudating wounds, macerated and slough wounds are often at risk of infection. About 8% of hospital in-patients in England develop infections and in intensive care units the figure raises to 23%.
In order to address the problem with particular reference to MRSA and Clostridium diflcile, a new E4.2 million consortium has been jointly created by the Biotechnology and Biological Sciences Research Council (BBSRC), the Medical Research Council (MRC), the National Institute for Health Research (NIHR) and the Welcome Trust in the UK. The projects the consortium plans to fund will range fiom organising a rapid response, springing into action if a particularly virulent strain of MRSA emerges and analysing its particular signature so it can be quickly detected and controlled, to finding the best ways to change the habits of hospital staff, patients and visitors to prevent infections from occurring and spreadiig. The consortium will look at issues such as quick detection and control of the spread of virulent strains of MRSA, the mode of spreading to hospital equipments such as latex gloves, and identify the best strategies for preventing the spread of infection. WOUND INFECTION Wound management that includes chronic wounds such as pressure sores, venous leg ulcers is one of the crucial areas which needed to be addressed for elderly and immobile communitiesbecause ageing and immobility weaken the intact of the skin that provide a physical barrier to the ingress of microorganisms. The skin is an important defence layer of the body as it protects fiom microorganisms, UV radiations and injury. It maintains the temperature of the body besides helping the body to gain vitamin D fiom sunlight. Wounds are formed when the skin is broken, and the healing process depends on the extent of damage to the epidermis, dermis and subcutaneous layers of the skin. Superficial wounds only damage the epidennis but the partial thickness and fullthickness wounds respectively damage the dermis and subcutaneous fatty tissues and/or bone. Wound healing by primary intention refers to the skin edges that have been brought together by sutures, and surgical adhesives. On the other hand, the secondary intention describes wound healing when the skin edges are not brought together and have to heal by contracting and filling up with granulating tissues. Wounds such as leg 0 Woodhead Publishing Limited, 201 0
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ulcers and pressure ulcers fall in this category, and they are chronic because it takes a longer time to heal. The skin in children and healthy adults is strong and inhospitable to pathogenic microorganisms but weak for elderly population and those confined to wheelchair. Once the line of defence is broken there is a risk of infection. Ageing decreases the eEciency of wound healing mechanisms. Once wound is formed replacement of epidermal cells, inflammatory response, sensory perception and barrier function decrease through the ageing process. Arterial and venous disease can delay wound healing, and are a common problem to the elderly population. The ultimate aim of wound management is to promote healing without microbial infection. Infection in the wound results in an increased production of exudate and delayed wound healing. Wounds in elderly people do, however, heal with good effect with carem management by selecting appropriate dressings. Wound dressings vary with the type of wound and management technique and no single dressing is universally applicable for healing all types of wounds. An ideal dressing is normally expected to provide barrier against dirt and other foreign bodies, provide humid environment at the wound surface that enhances wound healing, control exudate and be removed without trauma. The dressing should provide a barrier against pathogenic bacteria including the challenging MRSA (methicilh-resistant staphylococcus aureus) and MRSSA (Methicillin susceptible Staphylococcus aureus) bugs because cross-infection by bacteria through wound dressings and hospital textiles is increasingly common in hospitals and has been a major problem over several years. In the UK alone only a small number of patients (104) were infected by MRSA in 1992 but this figure rose to 4,904 in 2001. According to Office for National Statistics, the number of death in England and Wales involvingStaphylococcus aureus increased from 1,212 in 2001 to 2,083 in 2005. The death rate increased by 69% due to Clostridium dzJicile. Elderly people are vulnerable to risk as evidenced that the death rate in 2007 involving 85 and over age groups represents 767. It must be pointed out that certain bacteria, for example MRSA super bug shows resistance even to antibiotics. The bug is contagious and transmitted through skin contact as well as hospital textiles in hospital environment. It should be noted that the currently available wound dressings are effective against only a few types of bacteria and no such dressings provide a complete shield against a wide spectrum of pathogenic bacteria that include MRSA and MRSSA. In a broad sense, an ideal wound dressing should fulfil many major requirements which include high barrier properties against a broad spectrum of pathogenic microorganisms. HOSPITAL PROTECTIVEMATERIALS
Infection and cross-infection are nowadays more common in hospitals where the prevalence of microorganisms is high. Microorganisms are broadly classified as bacteria, fungi and viruses. Gram-positive bacteria include Staphylococcus aureus, Staphylococcus epidermidis, MASA and MRSSA and Gram-negative bacteria comprises of Proteus vulgaris, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Fungi (Candida albicons, Aspergillus niger), bird flue and swine flue are typical examples of viruses. Gram invented a staining method in 1884 to distinguish the bacteria based on colour changes. Gram-positive bacteria are purple and --negative bacteria are red after Gram staining. The bacteria cause infections such as superficial infections, acute gastro-enteritis, infections of wound, burn, respiratory and urinary tract. Infwtions associated with f h g i are: ear, nose and lung infections; 4
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tinea nigra of palms; white pildra of bear4 diaper rash athlete’s foot; ring worm; and tinea, pulmowy, mucosa and hair infections. It is known that textiles carry and transmit infections fiom one person to another through clothing, bedding and related textile products used in hospitals and other potentially risk environments, and laundering process do not remove the risk of infection. Therefore it is vital that textile materials with antimicrobial properties are developed by using the following principal techniques: 0 0 0
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Imbuing antibacterial agents into the fibres or depositing onto the fibres. Chemical modification of fibres by formation of covalent bonds. Coating on the surface of fabrics. Microencapsulationof antibacterial agents. Plasma treatments.
It is also crucial that the developed materials should possess antimicrobial activity against a wide range of microorganisms that include super bugs such as MRSA. Antimicrobial textiles can be either active or passive materials. It will be noted that the passive materials do not contain active substances but their surface structure (Lotus effect) produces a negative effect on the living conditions of microorganisms (antiadverse effect). Textile materials that contain active antimicrobial substances act upon either in or on the bacterilal cell. There are several antimicrobial agents such as quaternary ammonium compounds, antibiotics, iodophors, phenols, ureas, organosilicons and silver containing agents and they are mostly act upon either the bacterial cell during the metabolism or within the genome. For example, Triclosan (polychloro phenoxy phenol) inhibits the growth of microorganisms by using an electro-chemical mode of action to penetrate and disrupt their cell walls. When the cell walls are penetrated, leakage of metabolites occurs and other cell functions are disabled thereby preventing the organism fiom functioning or reproducing. Silver has been known to possess antimicrobial characteristics since ancient times. Silver and nanosilver containing antimicrobial agents, for instance sodium silver sulphadiazine- SSD, are widely used both in hospital textiles and wound dressings because silver is generally recognised as a safe and broad-spectrum antimicrobial agent. Silver acts as a heavy metal by imparting the bacterial electron transport system and some DNA function. In addition to the above synthetic antimicrobial agents, the natural product antimicrobial agents such as chitosan, aloe Vera, tea tree oil, eucalyptus oil, tulsi extracts, neem and a number of medicinal plants have been systematicallyexamined for potential use as effective antimicrobial agents in hospital textiles and wound dressings. The major advantages of using natuml antimicrobial agents over synthetic antimicrobials include lower incidence of adverse reactions and eco-friendliness. It should be mentioned that neem (Azadirachta indica) and tulsi (Ocimum basilicum) possess a rich source of antimicrobial compounds and are abundantly found in the Indian subcontinent. Recent studies have demonstrated the use of neem seed and bark extracts on cellulosic substrates to impart antibacterial activity against both Grampositive and Gram-negative bacteria. It is a well established fact that honey possesses broad spectrum of antimicrobial activity and has a long history of medical use. The high sugar content and the ability to produce hydrogen peroxide make the honey antimicrobial. There is increasing interest nowadays in using honey in wound management. Medical grade honey particularly Manuka honey has been successfully 0 Woodhead Publishing Limited, 2010
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used in a wide range of wound dressings for managing superficial wounds, sinus wounds, cavity wounds, burn wounds and the treatment of diabetic foot ulcers. BIBLIOGRAPHY 1 K Bertal, J Shepherd, C W I Douglas, J Madsen, A Morse, S Edmondson, S P Arms, A Lewis and S MacNeil, ‘Antimicrobial activity of novel biocompatible wound dressings based on triblock copolymer hydrogels, J Material Science, 2009 44(23) 6233-6246.
2 S H Lim and S M Hudson, ‘Reviewof chitosan and its derivative as antimicrobial agent and their uses as textile chemicals’, JMacromolecular Science, Polymer Reviews 2003 C43 223-269. 3 B S Atiyen, M Costagliola, S N Hayek and S A Dibo, ‘Effect of silver on burn wound infection control and healii: Review of the literature’, Korean J Dermatology, 2008 46(12) 1595 - 1602. 4 M Joshi, S W Ali, R Purwar and S Rajendran, ‘Ecotkiendly antimicrobial finishing of textiles using bioactive agents based on natural products, Zndian J Fibre & Text Res, 2009 34 295-304. 5 M Joshi, S W Ali and S Rajendran, ‘Antibacterialfinishing of polyestedcotton blend fabrics using neem (azadirachta indica): A natural bioactive agent’, J Applied Polymer Science, 2007 106 793-800.
6 NHSSB Wound Management Manual, Northern health and Social Services Board, 2005,4142.
7 National Prescribing Centre, ‘Modem wound dressing management’, Pres Nurse Bullt, 1999 l(2) 8. 8 C Basualdo, V Sgroy, M S Finola and J M Marioli, ‘Comparison of the antimicrobial activity of honey fiom different provenance against bacteria usually isolated fiom skin wounds’, Vet Microbial, 2007 124 375-381.
9 P C Mohan, ‘The role of honey in wound management’, J Wound Care, 1999 8(8) 415-418. 10 J Betts, ‘Guidelines for the clinical use of honey in wound care’, In: R Cooper, P Molan and R White, Honey in Modem Wound Management, HealthComm UK Ltd, Aberdeen, 2009.
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ANTIMICROBIAL PROPERTIES OF SILVER-CONTAINING CEUTOSAN FIBERS Yimin Qin and Changjun Zhu The Biochemical Materials Research and Development Center, Jiaxing College, 56 Yuexiu Road South, J i m 314001, Zhejiang Province, China. Email:
[email protected] ABSTRACT
In order to prepare antimicrobial silver containing chitosan fibers, silver sodium hydrogen zirconium phosphate with particle diameter < lum were mixed with the chitosan solution and made into fibers by the wet-spinning process. When in contact with solutions containing protein and metal ions, silver ions can be released from these fibers through chelation and ion exchange. This paper discussed the antimicrobial effect of chitosan fibers and silver containing chitosan fibers against three common types of bacteria, i.e., Candida albicans, Staphylococcus aureus and Pseudomonas pyocyanea. Results showed that the silver containing chitosan fibers have much stronger antimicrobial effect than the chitosan fibers.
Key words: chitosan fiber; silver containing chitosan fiber; antimicrobial property INTRODUCI’ION Silver has a long history as an antimicrobial agent[’-’], especially in the treatment of bums. While metallic silver is relatively inactive, silver ions are effective against a wide range of bacteria. When low concentrations of silver ions accumulate inside cells, they can bind to negatively charged components in proteins and nucleic acids, thereby effecting structural changes in bacterial cell walls, membranes and nucleic acids that affect viability[”81. In addition, although silver is a highly effective antimicrobial agent, it has a limited toxicity to mammalian cellsrg1. It was found that the use of silver containing wound dressings can increase the rate of epithelialisationby 28%, indicating a beneficial effect of silver ions to skin regeneration, in addition to its antimicrobial activity. In recent years, silver has been gaining importance as an effective antimicrobial agent that does not result in bacteria resistance. Silver containing antimicrobial products have been developed so that a low concentration of silver ions can be released over time. A number of laboratory studies have shown the excellent antimicrobial performances of the silver containing antimicrobial products[23 ‘I. This paper presents the results of a study on the antimicrobial properties of silver containing chitosan fibers.
EXPERIMENTAL A spinning dope was prepared by dissolving 3 kg of chitosan powder in 97kg of 1% aqueous acetic acid solution. 30 g AlphaSan RC5000 (a silver sodium hydrogen zirconium phosphate containing 3.8% by weight silver) was added into the solution and thoroughly mixed with the chitosan solution. After storage at room temperature for two days to remove the bubbles, fibers were produced by extruding the dope through a spinneret with 4,000 holes (hole diameter 80 um) at 12 d m i n into an aqueous 0 Woodhead Publishing Limited, 201 0
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coagulation bath containing 4% NaOH. The as-spun fibers were taken up at 7.2 d m i n and then stretched at 8OoCto the maximum extent. The fibers were then washed with water and acetone before being dried by hanging in air. Finally, the dry tow was cut to produce 50 mm length staple fibers. When analyzing the silver ion contents in the chitosan fibers, 0.5 g fibers were treated with 7 ml concentrated sulphuric acid until the fibers were fully digested. The mixture was then diluted to 100 ml with distilled water and filtered. The silver ion concentrationwas determined by using atomic absorption spectrometer. When testing the release of silver ions from the fibers, the fiber sample was placed in contact with 40 times its own weight of either distilled water, solution A or aqueous solutions containing different amount of protein. The British Pharmacopeia specified solution A as an aqueous solution containing 142 millimoles of sodium chloride and 2.5 millimoles of calcium chloride, representing the typical ion concentrationsof body fluid. The protein used was water soluble soya bean protein. After conditioning at specified temperatures for different periods of time, 5 ml solution was taken out and tested for silver ion concentrationby using atomic absorption spectrometer. The antimicrobial activity of the fibers was tested against three common strains of bacteria, i.e., Candi& albicans, Staphylococcus aureus and Pseudomom pyocyanea. The bacteria were suspended in 0.5% peptone water with the bacteria concentration at about 1.5x104to 1.5x105c~ml.35 ml0.5% peptone water were measured into looml conical flasks and to each of them were added 2.5ml of the bacteria suspension, with the bacteria concentration in the conical flask controlled at between l x l d and lx104 c W d . After that, 0.375 f0.002g of sterilized silver containing chitosan fibers were added into the conical flasks respectively. The fibers were placed in contact with the bacteria suspension; the conical flasks were placed in a water bath at 36OC and were shaken at a speed of 180 r/min for 8 hrs. 0.1 ml of the bacteria containing solution was then taken out to measure the colony forming units. The reduction in the number of bacteria is calculated in the following equation : Reduction in bacteria = [A-B]/A x 1000? Where : A : The average bacteria concentration in the control sample after shaking , cWml B : The average bacteria concentrationin the test sample after shaking , cWml
RESULTS AND DISCUSSION Figures 1 show the SEM photomicrographs of the silver containing chitosan fibers. It can be seen that although the silver containing chitosan fiber generally has a smooth surface structure, the Alphasan RC5000 particles are visible and can be seen embedded into the chitosan structure. When the fiber is wet with 0.1% aqueous acetic acid solution, it can be seen under optical microscope that the silver containing Alphasan RC5000 particles are fairly uniformly distributed inside the fiber structure, acting as the reservoir for releasing the antimicrobial silver ions.
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Fig 1: SEM Photomicrographof the silver containing chitosan fiber Figure 2 shows the release of silver ions when the silver containing chitosan fibers were placed in contact with three different solutions at 37 OC. With distilled water, the silver concentration was low and remained at about 0.137 u g / d over extended period of time. In both solution A and 2.9%aqueous protein solution, the silver concentrations in the contacting solutions were much higher than in distilled water. With solution A, the silver concentration slowly rose fiom 0.402 ug/ml at 30 min to about 0.654 ug/ml after 24 hrs. The silver concentration in the 2.9% protein solution was much higher than in solution A. At 4 hrs, the silver concentration in the protein solution was 1.31 ug/ml, about twice those measured in solution A after same period of contact with the silver containing fibers. 1.4 1 1.2
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Fig 3: Effect of temperature on the silver release when the silver containing chitosan fibers were in contact with solution A Figure 3 shows the effect of tempemture on the silver release when the silver containing chitosan fibers were in contact with solution A. After 24 hrs, the silver ion concentration in solution A were 0.370, 0.654 and 0.765 u g h l at 21, 37 and 65°C respectively, with the silver ion concentrationat 65°C roughly double that at 21°C. This shows that the rate of silver ion release can be significantly elevated when temperature is increased. It is possible that at a higher temperature, the fibers can swell more as water penetrates inside the fiber. In addition, the ion exchange process can also be accelerated at an elevated temperature. Figure 4 shows the silver ion concentrations when the silver containing chitosan fibers were in contact with aqueous solutions containing different amount of protein at 37 "C. It is clear that the silver ion concentration in the contacting solution is directly proportional to the protein concentration. The effect of a high protein concentration is fairly obvious, with the silver ion concentration in the 5% protein solution about 4 times that of the 1% protein solution after 30 min.
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Fig 4: Silver ion concentrations when the silver containing chitosan fibers were in contact with aqueous solutions containing different amount of protein at 37 OC The silver ions released from the silver containing chitosan fibers can act as an effective antimicrobial agent. Although chitosan is already well known for its antimicrobial properties, this is mostly due to the positive charge on the amine groups which controls bactetia growth by its ability to combine the negatively charged bacteria cells. Though this action can help limit the bacteria growth, its action is bacteriastatic rather than bactericidal. Table 1 shows the antimicrobial effect of the silver containing chitosan fibers against three common strains of bacteria. It is clear that with all three types of bacteria, the silver containing chitosan fibers are effective in reducing the bacteria count by more than 98%. In Table 2, the antimicrobial effect of chitosan fibers and silver containing chitosan fibers are compared against Candich albicans. Under the same test conditions, the reduction in bacteria count for the chitosan fiber is 78.62%, whilst for the silver containing chitosan fiber, the reduction is 97.22%. This clearly demonstrates that the silver containing chitosan fiber is more effective in controlliig bacteria growth than the chitosan fiber. Table 1. The antimicrobial effect of silver containing chitosan fibers against three common bacteria Type of Bacteria Bacteria Concentration YOReduction in Cfu/ml bacteria count Control Test sample Candida albicans 1 .46x105 2005 98.63 Staphylococcus aureus 1 . 2 1~o4 168 98.60 7.16 x 1O6 1 100 Pseudomom pyocyanea
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Table 2. The antimicrobial effect of chitosan fibers and silver containing chitosan fibers against Candida albicans Sample Control Chitosan Fiber Ag Chitosan Fiber Bacteria 54x10’ 1155 150 concentration,cWml % Reduction in 78.62 97.22 bacteria count
CONCLUSIONS This study has shown that silver containing chitosan fibers can be made by blending silver containing AlphaSan RC5000 particles in the spinning dope. Experimental results showed that when the silver containing chitosan fibers are placed in contact with either solution A or aqueous protein solution, silver ions can be released from the fiber through ion exchange and chelation. More effective in releasing the silver ions from the fiber takes place with chelation with protein molecules. It has been found that the silver containing chitosan fiber is more effective in controlling bacteria growth than the original chitosan fiber. Acknowledgement
This work was financially supported by the Natural Science Fund of Zhejiang Province, China (Grant No. Y405030). REFERENCES 1 C J Coombs, A T Wan and J P Masterton, ‘Do burns patients have a silver lining’, B u m , 1992 18(3) 179-184. 2 E A Deitch, A A Marino and V Malakanok, ‘Silver nylon cloth: in vitro and in vivo evaluation of antimicrobial activity’, J Trauma, 1987 27(3) 301-304.
3 J R Furr, A D Russell and T D Turner, ‘Antibacterial activity of Actisorb Plus, Actisorb and silver nitrate’, J. Hospital Infection, 1994 27(3) 201-208. 4 A B G Lansdown, B Sampson and P Laupattarakasem, ‘Silver aids healing in the
sterile wound: experimental studies in the laboratory rat’, Brit. J. Dermatol., 1997 137 728-735.
5 A D Russell and W B Hugo, Antimicrobial activity and action of silver, In: Ellis, G. P., and Luscombe, D. K. (eds). Progress in Medicinal Chemistry, Elsevier Science, London, 1994. 6 R C Charley and A T Bull, ‘Bioaccumulation of silver by a multispecies population of bacteria’, Arch. Microbiol., 1979 123 239-244. 7 S M Modak and C L Fox, ‘Binding of silver sulfadiazine to the cellular components of Pseudomonas aeruginosa’, Biochemical Pharmacology, 1973 22( 19) 2391 -2404. 12
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8 T N Wells, P Scully and G Paravicini, ‘Mechanisms of irreversible inactivation of phosphomannose isomerases by silver ions and flamazine’, Biochemishy, 1995 34 7896-7903.
9 M A Hollinger, ‘Toxicological aspects of silver pharmaceuticals’, Crit. Rev. Toxicol., 1996 26 255-260.
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COPPER-IMPREGNATEDANTIMICROBIAL TEXTILES; AN INNOVATIVE WEAPON TO FIGHT INFECTION Gadi Borkow, Anthony Felix and Jeffrey Gabbay Cupron Inc, Greensboro, USA
ABSTRACT A platform technology has been developed in which coppr oxide is impregnated or plated into polymeric fibres or cotton fibres, respectively, endowing the fibres with potent broad-spectrum anti-bacterial, anti-viral, anti-fungal and anti-mite properties [11. This durable platform technology introduces copper oxide-treated fibres and enables the mass production of woven and non-woven fabrics with no requirement for alteration of industrial procedures or machinery. This technology facilitates the production of autiviral gloves and filters (which deactivate HIV-1and other viruses); anti-bacterial selfsterilizing fabrics (which kill antibiotic resistant bacteria, including MRSA and VRE); anti-fungal socks (which alleviate symptoms of athlete's foot); anti-dust mite mattresscovers (which reduce mite-related allergies) and gauze (which is highly effective in promoting skin regeneration, closure of chronic wounds and the alleviation of bed sores). This paper will demonstrate the potential use of copper in new applicationsthat address medical issues of the greatest importance such as viral transmissions; nosocomial infections; wound healing and the spread of antibiotic resistant bacteria
COPPER AS A BIOCIDE Copper ions have been used for centuries to disinfect fluids,solids and tissues [2,3]. The ancient Greeks (400 BC) prescribed copper for pulmonary diseases and for purifying drinking water. The Celts produced whisky in copper vessels in Scotland around 800 AD, a practice that has continued to the present day. Copper strips were nailed to ship's hulls by the early Phoenicians to inhibit fouling, as cleaner vessels were faster and more manoeuvrable. Gangajal (holy water taken from the Ganges River) has been stored in copper utensils in Hindu households for centuries due to copper's anti-fouling and bacteriostatic properties. By the 18' century,copper had come into wide clinical use in the western world for the treatment of mental disorders and afflictions of the lungs. Early American pioneers moving west across the continent put silver and copper coins in large wooden water casks to provide them with safe drinking water for their long voyage. In World War II, Japanese soldiers put pieces of copper in their water bottles to help prevent dysentery. Copper sulphate is highly prized by some inhabitants of Africa and Asia for h e a l i i sores and skin diseases. NASA first designed an ionization coppersilver sterilizing system for its Apollo fights. Today copper is used as a water purifier, algaecide, fungicide, nematocide, molluscicide, and as an anti-bacterial and anti-fouling agent [4-81. It is considered safe to humans, as demonstrated by the widespread and prolonged use of copper intrauterine devices (IUDs) by women 19-11]. In contrast to the low sensitivity of human tissue (skin or other) to copper [12], micro-orgauisms are extremely susceptible to copper. Copper toxicity to micro-organisms, including toxicity to viruses, may occur through the displacement of essential metals from their native binding sites, from interference with oxidative phosphorylation and osmotic balance and from alterations in the conformationalstructure of nucleic acids, membranes and proteins [131. 14
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- polyester fibrescontaining3% (w/w) copper oxide particles (right panel). INCORPORATION OF COPPER OXIDE INTO NATURAL AND SYNTHETIC FIBERS U t i l i i g the properties of copper, two durable plafform technologies were developed [1,13]: the first one plates cotton fibres with copper oxide (Fig 1, left panel) and the second one impregnates polyester, polypropylene, polyethylene, polyurethane, polyolefin or nylon fibres with copper oxide (Fig 1, right panel). The fibres can be cut into short staple or produced in filament form and texturized, if so desired. The product yielded is a fibre that can be introduced at the blending stage of yarn production or directly into a woven or knit product so that no manufacturing processes are changed. Woven and non-woven fabrics can be produced.
BIOCIDAL PROPERTIES OF FABRICS CONTAINING COPPER OXIDE Antibacterial Exposure of gram positive or gram negative bacteria to fabrics containing copper oxide particles results in potent reduction in their viable titres (Table 1). Table 1: Antimicrobial properties of wpper-oxide impregnated fabrics
Type of Copper % of Copper Treated Fibres in Fabric (w/w) Plated Cellulose 0.2 0.2 0.2
0.2 Polyester
1 1 1
Polypropylene
3 3 3 3 0.5 0.5
1
Nylon
Name of Time (hr) % Reduction Orpanism Tested of E x D o ~ ~ r eof Titre Staphylococcusaureus 1 >99.8 MRSA 1 >99.5 VRE 1 99.5 Escherichia coli 1 >99.9 4 >99.9 Staphylococcusaureus Listeria 1 >99.8 Salmonella 2 >98.5 Escherichia coli 1 >99.9 Staphylococcus aureus 3 >99.9 Escherichia coli 3 >99.9 Klebsiella pneumoniae 3 >99.9 Enterococcus 3 >99.9 Staphylococcusaureus 2 >99.9 Escherichia coli 1 >99.9
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Exposure of fungi to fabrics containing copper oxide particles results in potent reduction in their viable titres (Table 2). Table 2: Antifungal properties of copper-oxide impregnated fabrics Name of Time (hr) % Reduction Type of Copper % of Copper Orrranism Tested of Ex~osure of Titer Treated Fibres in Fabric (w/w) Plated Cellulose 0.2 Candida albicans 24 >99.9 Candida albicans 24 >99.9 Polyester 0.5 1 Tricophyton mentagrophytes 24 >99.9 1 Tricophyton rubrum 24 >99.9 1 Aspergillus niger 24 >%.9 3 Candida albicans 24 >99.9 Polypropylene 24 >99.9 Nylon 0.5 Candida albicans The American Association of Textile Chemists and Colorists (AATCC) Test Method 100-1993 was used to determine the biocidal properties of the fabrics against the bacteria and h g i tested. The initial bacterial or fungal inoculum used varied between lx105 to 4x106 colony forming units (cfu)/sample. These tests were carried out by independent laboratories: AminoLab Laboratory Services, Weizmaun Industrial Park, Nes Ziona 79400, Israel, and Hy Laboratories Ltd., Park Tamar, Rehovot 76325, Israel.
Antiviral Filters containing copper oxide-impregnated polypropylene fibres can reduce infectious titres of a panel of viruses spiked into culture media (Table 3). Enveloped; non-
enveloped; RNA and DNA viruses were affected, suggesting the possibility of using copper oxide-containing devices to deactivate a wide spectrum of infectious viruses found in filterable suspensions. Prolongation of the exposure of these micro-organisms to the copper oxide-containing fibres further reduced their viable titers. Table 3. Reduction of infectiousviral titers by copper-oxide containing filters % InfectivitvReduction HN-1 >99.99 Punta Tor0 >99.99 99.99 Rhinovirus2 99.99 Pichinde 99.95 CMV 99.95 Measles 99.5 Influenza A WNV 99.5 99 AdenovirUs 99 RSV 96 Paraintluenza3 95 Yellow Fever 94 VEE Vaccinia 80 16
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The CMV testing was done at the Ben Gurion University, Beer Sheva, Israel by Dr. Shemer-Avni; HIV-1 and Adenovirus testing was done in Cupron Biosafety Viral Laboratory, Rehovot, Israel. All other viruses were tested at the Institute for Antiviral Research, Utah State University, Utah, USA. Anti-mite efficacy
Figure 2 shows the result of an experiment in which the effect of two fabrics, one containing 0.4% and one containing 2% copper oxide (w/w), were tested for anti-mite activity. The house dust mite tested was Dermatophagoiaks fwinae. While during the first 12 days of the experiment all mites exposed to control fabrics were alive, more than 60% and 100% of the mites exposed to the 2% copper fabric were dead afier 1 and 5 days, respectively. Approximately 50% of the mites exposed to the 0.4% copper fabrics died within 12 days of exposure to the fabrics. After 47 days of culture, 86% and 67% of the mites in the absence of any fabric and in the control fabric containers were alive, while all mites exposed to the 0.4% copper fabric were dead. This and other experiments with mites were conducted under a subcontract agreement by Dr. Kosta Y. Mumcuoglu fiom the Department of Parasitology, Hebrew University-HadassahMedical School, Jerusalem 91 120, Israel.
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CLINICAL STUDIES Athlete’s foot efficacy Fifty six individuals s e e r i n g fkom athlete’s foot (tineu pedis) were given socks containing 1% copper-oxide in the soles of the socks. The individuals were asked to wear the copper-socks on a daily basis. During this period the individuals did not receive any local or systemic anti-fungal treatment and their feet were monitored by a podiatrist. The following measures were studied: erythema, buming and itching, oedema, scaling, vesicular eruptions and fissuring. In all attributes there was a significant improvement or resolution of the attributes studied in an average follow up of 9 days (Fit3 3).
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Healing of diabetic ulcers Copper is a key player in many of the complicated processes that together comprise the wound repair mechanism. For example, copper stimulates the formation of new capillaries in the skin via induction of vascular endothelial growth factor (VEGF), copper stabilizes fibrinogen [14,15] and collagen and copper modulates inkgrins expressed during the final healing phase [1 61. Thus, taking together the potent biocidal activities of copper [131, the very low risk of adverse skin reactions associated with copper [12,17],and its roles in the wound healing process, strongly support the notion that the addition or application of copper or copper containing products, such as band aids and gauze containing copper, to wounds may significantly enhance the wound healing process. Indeed, in preliminary data demonstrate that treating chronic diabetic ulcers, which failed or responded poorly to conventional treatments, with copper oxide containing pads, results in significant closure and resolution of the chronic ulcers. One such example is shown in Figure 4.
Figure 4. Healing of a chronic ulcer in the foot of a 71 years old diabetic patient. The wound did not close even when treated for 9 months by conventional treatment (oral antibiotics, Acticoat Absorbent, Allevyn, Apligraf and sharp debridement).
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DISCUSSION Permanent or durable binding of inorganic compounds to organic substrates is extremely difficult, especially for mass production processes. By utilizing the properties of copper, two inexpensive platform technologies were developed which permanently bind copper to textile fibres from which woven and nonwoven fabrics can be produced. The introduction of copper oxide at the early stages of the production cycle enables the use of the copper-treated fibres in many manufacturing processes without alerhg manufacturing procedures or equipment, allowing for rapid and simple production of fabrics with potent biocidal qualities. Animal studies demonstrated that the copper treated fibers do not possess skin sensitizing properties [1,18]. Furthermore, no individual who used socks containing copper-impregnated fibres to alleviate their athlete’s foot conditions reported any negative effects caused by the socks [18,19]. Similarly, none of 100 patients, who slept on sheets containing copper treated fibres, reported any adverse effects [18]. These findings are in accordance with the very low risk of adverse skin reactions associated with copper [12]. The possibility of introducing copper oxide into fabrics may have significant ramifications. One example is the reduction of nosocomial infections in hospitals. Although the contribution of airborne transmission of pathogens to nosocomial infections has been controversial, much data is accumulating in support of the notion that airborne transmission of bacteria contributes significantly to hospital acquired infections (reviewed in Ref [20]). Airborne transmission is known to be the route of infection for diseases such as tuberculosis and aspergillosis. Recently it has been implicated in nosocomial outbreaks of MRSA [2 1,221, Acinetobacter baumannii [23] and Pseudomonas aeruginosa [24]. It was found that 65% of the nurses who performed activities on patients with MRSA in wounds or urine, contaminated their nursing uniforms or gowns with MRSA [20]. Hospital ventilation systems have also been implicated with nosocomial MRSA outbreaks [20]. Importantly, it has been demonstrated that sheets which are in direct contact with the patient’s skin and its bacterial flora are an important source of airborne bacteria [25,26], including MRSA [27l. Activities, such as bed-making, have been shown to release large quantities of micro-organisms into the atmosphere, only to fall back to background levels 30 minutes after bed-making. The data for the hallway also revealed that the bed-making process dispersed micro-organisms around the building [28]. In an ongoing study at the Banilai Hospital in Israel, bacterial colonization of sheets, including MRSA, has been found in 22 out of 30 sheets examined (Dr. Y. Mishal, personal communication and Ref [18]). MRSA spread also occurs though indirect contact by touching objects such as towels, sheets, wound dressings and clothes contaminated by the infected skin of a person with MRSA (CDC, Fact Sheet. 7 March 2003. Mt~://www.cdc.~ov/ncidod/dhaR/ar m a ca public.htm1). We submit that the use of self-sterilizing fabrics, such as pyjamas, sheets and pillow covers, in a hospital setting, will significantly reduce the airborne and inchect contact dissemination of bacteria and other micro-organisms in hospital wards, thus reducing the rate of nosocomial infections. Indeed, prehinary data with 30 patients, who slept overnight on regular sheets and then overnight on sheets containing 90% regular cotton fibres and 10% copper oxide-impregnated fibres, demonstrate a statistically significant lower bacteria colonization on copper oxide-containing sheets than on regular-sheets [18], strongly supporting our hypothesis. 0 Woodhead Publishing Limited, 2010
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House dust mites O M ) are considered to be an important source of allergen implicated in allergic asthma, rhinitis, conjunctivitis and dermatitis [29]. By using copper oxide containing fibres in fabrics, the HDM population can be controlled and, if enough copper is present in the fabric, the mites can be eliminated entirely. In conclusion, this paper presents potential uses of copper in new applications that address medical concerns of the greatest importance. Implementation of even a few of the possible applications of this technology may have a major effect on the lives of many.
REFERENCES 1 G Borkow and J Gabbay, 'Putting copper into action: copper-impregnated products with potent biocidal activities,' FASEB J2004 18 1728-1730.
2 S S Block, 'Definition in terms,' Disinfection, Sterilisation and Preservation, 2001 9 1857. 3 H H A Dollwet and J R J Sorenson, 'Historic uses of copper compounds in medicine,' Trace Elements in Medicine, 2001 2 80-87.
4 T E Cooney, 'Bactericidal activity of copper and noncopper paints,' Infect. Control HOT. Epidemiol. 1995 16 444-450.
5 J J Cooney and R J Tang, 'Quantifying effects of antifouling paints on microbial biotilm formation,' Methods Enzymol. 1999 310 637-644.
6 J E Stout, Y S Lin, A M Goetz, and R R Muder,'Controlling Legionella in hospital water system: experience with the superheat-and-flush method and copper-silver ionization,' Infect. Control Hosp. Epidemiol. 1998 19 911-914. 7 D J Weber and W H Rutala, 'Use of metals as microbivides in preventing infections in healthcare,' Disinfection, Sterilization, and Preservation. S . S . Block, ed., (Lipphcott Williams and W i W , New York, 2001), 415-430.
8 W D Fraser, A Quinlan, J Reid, and R N Smith, Huntingdon Res Center: Primary screening of copper compounds for herbicidal, nematocidal, fungicidal and bactericidal activity. INCRAProjectno.211,43.2001. 9 'Copper IUDs, infection and infertility,' Drug Ther. Bull. 2002 40 67-69.
10 X Bilian, 'Intrauterine devices,' Best. Pract. Res. Clin Obstet. Gpaecol. 2002 16 155-168.
1 1 D Hubacher, R Lara-Ricalde, D J Taylor, F Guerra-Infante and R GuzmanRodriguez, 'Use of copper intrauterine devices and the risk of tubal infertility among nulligravid women,'N. Engl. JMed 2001 345 561-567. 12 J J Hostynek and H I Maibach, 'Copper hypersensitivity: dennatologic aspects--an overview,' Rev. Environ. Health 2003 18 153-183. 20
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13 G Borkow and J Gabbay, 'Copper as a biocidal tool,' Curr. Med Chem 2005 12 2 163-2175. 14Z Ahmed, B D Idowu, and R A Brown, 'Stabilization of fibronectin mats with micromolar concentrations of copper,' Biomaterials, 1999 20 201-209. 15 Z. Ahmed, A Briden, S Hall, and R A Brown, 'Stabilisation of cables of fibronectin
with micromolar concentrations of copper: in vitro cell substrate properties,' Biomaterials, 2004 25 803-812. 16 I Tenaud, I Sainte-Marie, 0 Jumbou, P Litoux, and B Dreno, 'In vitro modulation of keratinwyte wound healing integrins by zinc, copper and manganese,' Br. J Dermatol. 1999 140 26-34. 17 R W Gorter, M Butorac, and E P Cobian, 'Examination of the cutaneous absorption of copper after the use of copper-containingointments,' Am JTher. 2004 11 453-458.
18 J Gabbay, J Mishal, E Magen, R C Zatcoff, Y Shemer-Avni, and G Borkow, 'Copper oxide impregnated textiles with potent biocidal activities,' Journal of Industrial Textiles, 2006 35 323-335. 19R C Zatcoff, 'Healthstidem Socks - Footware to a higher standard,' Podiatry Management, 2005 NovemberAlecember, 202-203.
20 C B Beggs, The airborne transmission of infection in hospital buildings: fact or fiction? Indoor Built Environ, 2003 12 9-18. 21 E A Mortimer, Jr., E Wolinsky, A J Gonzaga, and C H Rammelkamp, Jr., 'Role of airborne transmission in staphylococcalinfections,' Br. Med. J. 1966 1 3 19-322. 22R D Wilson, S J Huang, and A S McLean, 'The correlation between airborne methicillin-resistant Staphylococcus aureus with the presence of MRSA colonized patients in a general intensive care unit,' Anaesth. Intensive Care, 2004 32 202-209. 23 A T Bemards, H M Frenay, B T Lim, W D Hendriks, L Dijkshoom, and C P van Boven, 'Methicillin-resistant Staphylococcus aureus and Acinetobacter baumaunii: an unexpected difference in epidemiologic behavior,' Am J Infect. Control, 1998 26 544551. 24 H G Grieble, T J Bird, H M Nidea, and C A Miller, 'Chute-hydropulping waste disposal system: a reservoir of enteric bacilli and pseudomonas in a modem hospital,' J Infect. Dis. 1974 130 602-607. 25 D Coronel, A Boiron, and F Renaud, 'Role de l'infection sur la contamination microbienne des draps des patients,' Reanimation, 2000 9s 86-87. 26 D Coronel, J Escarment, A Boiron, J Y Dusseau, F Renaud, M Bret, and J Freney, 'Infection et contamination bacterienne de l'environnement des patients: les draps,' Reanimation 2001 lOS, 43-44. 0 Woodhead Publishing Limited, 201 0
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27 V W Greene, R G Bond, and G S Michaelsen, 'Air handling systems must be planned to reduce the spread of infection,' Mod Hosp. 1960 95 136- 144. 28 T Shiomori, H Miyamoto, K Makishima, M Yoshida, T Fujiyoshi, T Udaka, T Inaba, and N Hiraki, 'Evaluation of bedmakm * g-related airborne and surfme methicillinresistant Staphylococcus aureus contamination,' J Hosp. Infict. 2002 50 30-35. 29 S A Brunton and R L Saphir, 'Dust mites and astha,' Hosp. Pract. (OfM) 1999 34 67-2,75.
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A REVIEW OF TBE ROLE OF MICROWAVES IN THE DESTRUCTION OF PATHOGENIC BACTERIA A. S. Lamb and E. Siores Institute for Materials Research and Innovation,The University of Bolton, Bolton, Deane Road,BL3 5AB,UK
ABSTRACT The destruction of food bacteria has been the subject of research and development in many disciplines for a very long time. Solutions have emerged from time to time but ultimately resulted in the on-going quest for keeping abreast of new bacteria strains emanating from old. Methods and techniques have proved to be reactive rather than proactive and thus the challenge has been a perpetual and a prevalent one. This paper provides a state of the art potential avenue for bacteria destruction using microwaves and outlines the work that has been undertaken by various researchers in the field. Outcomes presented support, to a certain extend, the viability of fixed frequency microwaves in the treatment of food bacteria and suggest especially that the pulsed microwave methods and techniques used can lead to the desired aims and objectives. However, their successful implementation in industry has been limited due to the fact that at fixed frequency microwave energy is absorbed not only by the bacteria but also by the food carrier. In this case, the benefits of the technology have not been fully realised since bacteria are ultimately thermally treated but often destructed at lower temperatures than conventional. The possibility of utilising pulsed microwaves and variable microwave frequency approaches are explained together with the advantages and limitations for the destruction of bacteria without affecting the carrier load.
Key words:Variable frequency microwaves, microbacteria, pathogenic bacteria sterilization, food poisoning, microwaves
MICROWAVEINTERACTIONS WITH MATERIALS Bows (1999) provided the following equation for calculating the microwave power penetration depth, Equation 1
where D, is in centimetres, f is in GHz and E’ is the dielectric constant, whilst E” is the dielectric loss factor, Simply, the higher the frequency, the less the depth of penetration. E’ and E” can be dependent on both frequency (0 and temperature, the extent of which depends on the foodstuff to be studied. The rate of microwave heat generation per unit volume, Q, at a particular location within the foodstuf€during the microwave irradiation process is given by the following equation from Buf€ler(1993), and Datta and Anatheswaran (2000): Q =2 A f
E”
E2
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Equation 2 23
where E is the strength of the electric field of the wave at the location, f is the frequency of the wave (typically 2450 MHz), EO is the permittivity of free space (a physical constant), and E” is the dielectric loss factor ( a material property called the dielectric property representing the material capacity to absorb microwaves). There is another dielectric property, dielectric constant,which affects the strength of the electric field inside the food product. The dielectric property depends on the composition of the food product, with moisture and salt being the two determinauts of variability interest (Mudgett 1986). The subsequent temperature rise in food depends on the duration of heating, the location of the food in the reactor, the convective heat transfer at the surface and the extent of evaporation of the water inside the food and at its surface (United States Food and Drug Agency 2000). Furthermore, Calvao and Olano (1992) concluded that heating by microwaves can be faster and more uniform thus being more effective and efficient than conventional heating.
FIXED F’REQUENCY MICROWAVE INTERACTIONS WITH BA-RIA The temperature increase in some materials when exposed to high fiequency electromagneticfields (above 108Hz)has been known since 19th century and utilised in limited applications in the early part of the 20th century (Zlotorzynsk 1995). In conventional thermal processes, slow heat conduction &om the heating medium to cold spots in the food stuff, often results in treatment of the material at the periphery of the heating container which is far more severe than that required to achieve commercial sterility (Datta and Hu 1992). Microwave energy is a non-ionizing form of radiation and as such it has been tested to study the effectiveness in destroying bacteria and extending the shelf life of meat products without aEecting the quality, taste or reducing the weight of the product. The microbial treatment under microwaves irradiation is a function of power, firesuericy range, time and temperature. The technique using fixed frequency microwaves has been used in the pasteurization of milk, yoghurt and dairy products and has had an effect on reducing the bacterial count and deactivating enzymes at a lower energy input level and destruction as compared with conventional means of pasteurizationtechniques in use (US Food and Drug Administration2000). Sterilization was amongst the earliest applications considered for microwave usage (Fleming 1944; Electronic Sterilization 1945; Swenson 1949) and this went hand in hand with the exploration of the biological effects of the microwaves on cells. The main advantages of the fixed frequency microwaves (at 915MHz and 2450MHz) were that it allowed continuous sterilization through microbial destruction (Mudgett 1986:Mudgett and Schwartzberg 1982) and as such industrial microwave pasteurization and sterilization have been reported for over forty years (Jeppson and Harper 1967:Kenyon et al 1970: Mudgett and Schwartzenbenrg 1982: Decareau 1985: Schlegel 1992: H a r h g e r 1992:Topps 2000) There has also been investigation with regards to pasteurization means for hermetically sealed food packaging including meat, provided that the packaging material is transparent to microwave energy. Since different areas are subjected to different power levels at different times, the power distribution can be uneven and can result in multiple hot spots within the food product (Laufet al, 1993). It is timely to reveal the effect of fixed frequency microwaves on a number of bacteria and the following section summarises results that have been obtained so far.
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WORK CARRIED OUT AT THE UlVVERSlTY OF BOLTON The microwave power input parameters were optimised through the irradiation of Escherichia coli, Stavhvlococcus aureus and Salmonella DOOM, which has been investigated through exposure to fixed frequency microwaves at varying time sets of 10 seconds, 30 seconds and 45 seconds and low power ranges between 50W and 300W. The lethal effect of the treatment was validated via the use flow cytometry.
H s
120
100
Tlme
Paver (w)
3mw
2mw
IOOUV
ww
T i W P o w e r Settings
Figure 1. Effect of E. coli at Merent power settings and different time intervals. It is evident from Figure 1, that at each power setting the initial reading at ten seconds shows approximately about a half population cell mass reduction, ranging h m 41.13% at 200W and up to 62.34% at 50W. The reduction then increases at 30 second time interval with higher bacterial mass reduction rate at 300W (88.52%) and the lower kill rate of 73.11% at 200W. The highest bacterial kill effect (98.1%) is observed at 45 second interval at 300W power setting. On the other hand, the lowest readings are observed at 200W and lOOW of 89.65% kill rate, in both cases. With regard to Staphylococcus aureus, it is evident from Figure 2 that the greatest bacterial kill rate of 84.27% is achieved at 10 seconds time interval at lOOW, whilst the lowest rate of 31.4% is observed at 50W. At 30 second time interval, the kill rate of 88.38%, 89.4%, 91.42% and 87.18% for 330W, 200W, lOOW and 50W power settings are obtained respectively. The results at 45 seconds show the bacterial masses of 99.9%, 97.44%, 98.7% and 96.48% for the power settings of 300W, 200W, lOOW and 50W respectively.
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"
10 3 45
1ni Power
MI
3nDrv
10 30 45
10 30 45
aDoW 1O h T i d P o w r Settings
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Figure 2. Effect of Staphylococcus aureus at different power settings and different time intervals It can be seen in Figure 3 that at each power setting the Salmonellapoona reduction rate is quite low when compared to higher power settings. At 300W the reduction rate is only 34.42%,at 200W it is 48.67%a better result showing an almost half population of bacteria is destroyed. At lOOW and 50W the kill rates are 29.83% and 20.46% respectively. As the exposure time is increased to 30 seconds the kill rates increase to 68.96%for 300W, 79.54%for 200W, 76.1% for lOOW and 70.04%for SOW,thus the rate increased as did the exposure time as would be expected. At 45 seconds exposure time the reduction rates are 90.91%, 89.57%, 93.98% and 96.18% for the respective 330W, 200W, IOOW and 50W power settings.
Pawar
(w)
Timepower Settings
Figure 3. Effect of Salmonellapoona at different power settings and different time intervals
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FLOW CYTOMETRY Flow cytometry is a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid. It allows simultaneous analysis of different cell parameters such as physical andor chemical characteristics of single cells flowing through an optical and/or electronic detection apparatus. A beam of light of a single wavelength is directed onto a hydro-dynamically focused stream of fluid. A number of detectors are aimed at the point where the stream passes through the light beam; one in line with the light beam (Forward Scatter or FSC) and several perpendicular to it (Side Scatter (SSC) and one or more fluorescent detectors). Each of suspended particles in the solution being measured which pass through the beam scatters the light in some way, and fluorescent chemicals found in the particle or attached to the particle may be excited into emitting light at a lower ftequency than the light source. This combination of scattered and fluorescent light is picked up by detectors present in the Flow Cytometer. Figures four and five show a Flow Cytometxk representation of dead cells and the Irradiated sample subjected to 50W for 45 Seconds. 1000
1000
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100
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3 10
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1
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E.coli Dead as Shown by Flow Cytornetry
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E.coli afier Irradiation as Shown by Flow Cytometry
Figure 3 Dead E.coli as representedm Flow
w-
Figwe 4 E.cda h irradiation as represented by ~@wcytometry
CONCLUDING REMARKS
The low time high power approach undertaken compliments the work of Cunningham and Albright (1977) and Cunningham 1978; 1980 who applied microwaves to poultry meat for shorter periods of time. Meat treated in less than 20 seconds showed “no drastic changes in appearance ofphysical characteristics.” (Cunningham, 1980). Results obtained for Staphylococcus aureus at the higher power settings of 200W i.e. kill rates of 97.44% and 89.40% at 45seconds and 30 seconds respectively and results obtained at 300W at 30sconds and 45 seconds of cell mass reduction rates of 88.38% and 99.9%respectively compare favourably to the work canied out by Yeo et al(1999) who reported a total kill at 11 0 seconds but at the higher power settings of 800W. This similar pattern has been observed in all the power time relationships tested, with an 0 Woodhead Publishing Limited, 2010
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initial kill rate that rose with the exposure time and the final bacterial destruction rate is always around the 95% level. With respect to Escherichia coli the same pattem of rising bacterial cell mass reduction rates has been observed with the final figures of: 300W giving 98.1% effectiveness, at 200W the figure is 89.65% at lOOw the figure is also found to be 89.65%. The figure for bacterial death rate obtained for Exoli is 94.9%. This suggests that this power level and exposure time are the optimum time and power settings. This is also supported the work of Meng and Doyle (1998) who reported that E.coli is destroyed by hating at 68.3OC for 16 seconds, allied to this Yaghmaee and Durance (2005) investigated the effects of microwaves on the survival and injury of E.coli. They reported that E.coli is sensitive to temperature change under microwave heating; this theory was backed up by the work carried out in this experiment. The flow cytometry work as represented by Figures 3 and 4 prove that the microwaves at low power and time have optimum killing rates and have a biocidal effect. We can conclude that each bacterial type has an optimum temperature and time relationship which gives maximum cell mass reduction. The work was carried under controlled conditions, with the microwave irradiation canied out in the confiies of a waveguide as opposed to the cavity of a microwave oven. Throughout the experimental work the temperature of the carrier load did not exceed 4OoC meaning that microwave energy was reactive in destroying bacteria only without affecting the carrier load which could in theory be the foodstuff. The experimentation proved that bacteria can be destroyed through microwave process optimisation at relatively low levels of power input and exposure time at the fixed frequency of 2.45GHz. This finding argues that energy levels can be used for selective destruction without affectingthe carrier load.
Acknowledgements Engineering and Physical Sciences Research Council (EPSRC),UK. The Technical Staff,Institute for Materials Research and Innovation, The University of Bolton.
REFERENCES 1 J R BOWS,‘Variable frequency microwave heating of food’, J of Microwave Power and Electromagnetic Energv, 1999 34(4) 227-238. 2 C R Buffler, Microwave cooking andprocessing: Engineeringfirndamentals for the food Scientist, Van Nostrand Reinhold, New York, 1993.
3 M M Calvo and A Olano, Thermal treatment of goat’s milk, Cienc. Tecnol. Aliment, 1992 32(2) 139-152. 4 A K Datta, Fundamentals of heat and moisture transport for microwaveable food product and process development, A. K. Datta and R. C. Anatheswaran. (4s.). Handbook of Microwave Technology for Food Applications. Marcel Dekker, Inc. New York, 2000. 5 A K Datta and W Hy Quality optimization of dielectric heating processes. Food Technol,1992 46(12) 53-56.
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6 R V Decareau, Pasteurization and Sterilization. Microwaves in the food processing industry. Academic Press, 1985. 7 Electronic Sterilization,Am Niller Process, 1945 73(4) 43-48. 8 G A Evrendilek, Q H Zhang and E R Richter, (1999) ‘Inactivationof E.coli 0157:H7 and E.coli 8739 in apple juice by pulsed electric fields’, J of Food Protection 62(7) 793796.
9 H Fleming H, ‘The effects of high frequency fields on microorganisms’, Electrical Engineering, 1944 63( 1) 18-21. 10 L Harlfinger, ‘Microwavesterilization’,Food Technol, 1992 46(12) 57-61. 1 1 M R Jeppson and J C Harper, Microwave heating substances under hypostatic pressure. Cryodry Corporation. US Patent Office 3 335 253,1967. 12 E M Kenyon, D E Westcott, P La Casse and J Gould, ‘A system for continuous processing of food pouches using microwave energy’, J. Food Science, 1970 36(2) 289293. 13 R J Lauf, D W Bible, A C Johnson and C A Everleigh, ‘2-18 GHz broadband microwave heating systems’, Microwave J,November 1993 24-34. 14 R Mudgett, ‘Microwave properties and heating characteristics of foods, an overview’, Food Technology, 1996 M(6) 84-98.
15 R Mudgett and H Schwartzberg, (1982) ‘Microwave food processing: pasteurization and sterilization- a review’, American Institute of Chemical Engineers, Symposium Series, 78(2 18) 1- 1 1. 16 W Schlegel, ‘Commercial pasteurization and sterilization of food products using microwave technology’, Food Technol, 1992 46(12) 62-63. 17 T Swenson, Process for pasteurization and enzyme activity of fiuit by electronic heating, US Patent Office, Pat No 2 476 251,12 July 1949. 18 R Topps, Managing Director, Tops Foods, Lammerides 26, Olen, Belgium, 2000. Web Site- http://www.tomfoods.com
19 U.S Food and Drug Administration Centre for Food Safety Applied Nutrition (2000) Kinetics of Microbial Inactivation for Alternative Food processing Technologies Microwave and Radio Frequency Processing, http://www.f d a . g o v / F o o d / S c i e n c e R e s e a r c h / s d u c m 100158.htm 20 A Zlotorzynsk, ‘The application of microwave-radiation to analytical and environmental chemistry’, Critical Revs in Analytical Chem, 1995 25 43-76.
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ANTIMICROBIAZ,BIOACTLVE BAND-AIDSWITH PROLONGED AND CONTROLLED ACTION Petar Skundric', Ljiljana Simovic', Mirjana Kostic', Adela Medovic', Katarina Milosevic2,Suzana Ditrijevic' 'Faculty of Technology and Metallurgy, Belgrade, Serbia 'Faculty of Pharmacy, Belgrade, Serbia
ABSTRACT The paper discusses the antimicrobial bioactive band-aids, a modem means of wound management and healing, which are effective against a wide spectrum of microorganisms. Ion-exchange fibres and nonwoven textile materials composed of PP/viscose blend were used as a textile basis. Antimicrobial bioactive band-aids were manufactured in two routs: - by chemisorption of gentamicin sulfate by ion-exchange fibres; and - by adhesion of gentamicin sulfate on nonwoven material with the aid of a polymer carrier (chitosan). For assessment of antimicrobial activity, the diffiion method on an agar medium has been used. Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella, Escherichia coli and Candida albicans have been utilised. The kinetics of active substance desorption has been examined through dissolving rate of medical substance fiom transdermal band-aid in vitro. Physical-chemical foundations and kinetics of desorption of gentamicin sulfate in vifro are described by a mathematical model which can be used for prognosis of prolonged release of medical substance fiom band-aid as a transdermal system.
Key words: Bioactive textile, antibacterialfibres, gentamicin sulfate INTRODUCTION Last decades of the 20& century were marked by an emphasiig of the protection of man's health and its prevention from infections by microorganisms' actions. It is well known that disinfection materials offer almost an instantaneous, but short lasting solution for microbes' removal. On the contrary,antimicrobial remedies are produced to offer a long-lasting solution for pathogeneous microbes' elimination. A great contribution to R&D of antimicrobial materials gave researchers fiom Japan, USA, Switzerland, Great Britain, Russia, Poland, Austria and France. However, the greatest contribution undoubtedly belongs to Japanese, in this moment presenting world leaders in manufacturingof antimicrobial textile materials [1-20]. For manufacturing antimicrobial textiles many inorganic antibacterial (resistant on high temperatures) agents are used. Good samples contain metal silver and zinc ions built into fibres during polymer synthesis process or during spinning of chemical fibres. Literature survey related to the application of antibacterial preparations for suppression and destroying of infection in different kinds of wounds shows that silver in fibres [3141, fabrics [4-7,181 knits [8,9] and nonwovens [10,11] has been used extensively. Besides silver, both zinc and copper are also used as antibacterialpreparations. For treatment of natural fibres, many organic antibacterial chemicals are used, for example quaternary ammonium compounds [14]. Among numerous antimicrobial 30
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textile materials, special attention should be paid on antimicrobial biotextile materials used for wound dressing and healing. The amplification of antimicrobial action may be attained by using special antibiotics or their combination [15-20]. At the Textile Engineering Department of the Faculty of Technology and Metallurgy in Belgrade, an intensive research on biomedical textile materials with antimicrobial and combined effects is recently conducted. Besides antibiotics, honey and essential oils of different plants - fir, rosemary and St.Joh’s worth- were used to attain biological activity of medical textile materials [21-241. To impart antibacterial activity on textile materials the following techniques were used: chemical modification ensuring biocide or biostatic bondmg on fibre by chemical bonds (chemisorption); - fixation of preparation into super molecular structure of fibre according to inclusion type (physical bond), i.e. physical modification; and - deposition of preparation on fibre in the form of low-soluble substances, by means of polymers or low-molecular agents-mediators (possibility of bonding by any bond type and in Merent modifications).
-
It has been shown in our previous research [22] that antimicrobial biomedical textile material based on PAN fibres and nonwoven textile showed considerable activity against different strains of bacteria. The amounts of bonded antibiotic are sufficient to impart desirable antibacterial activity in fibres due to the fact that Gram-negative bacteIia strains (Escherichia coli and Pseudomonas aeruginosa) are sensitive to gentamicin with minimum inhibitory concentrations within a range of 0.06 to 8mg per ml. Among the Gram-positive organisms, most strains of Staphylococcus aureus are highly sensitive to gentamicin with minimum inhibitory concentrations within a range of 0.12 to lmg per ml[25]. In this work, kinetics of removal of antibiotic deposited in vitro has been studied with the use of Franc’s cell for continual removal of medicals.
EXPERIMENTAL Materiala Fibrous materials 0 Ion-exchange acrylic fibres (PAN), with ion-exchange capacity (IEC) 2,O and 3,O mmollg and with linear density 2,2 dtex Nonwoven fabric based on ion-exchange acrylic fibres, with ionexchange capacity (IEC) 3,O 0 Nonwoven fabric based on blend of polypropylene/viswse, both fibres having same linear densities- 1,7 dtex. Antimicrobial agents Gentamicin sulfate, a product of pharmaceutical industry “Galenika”, Belgrade
Preparation of antimicrobialband-aids In this work, biotextile antimicrobial medical plasters have been designed and developed by using the following two methods: 0 Woodhead Publishing Limited, 201 0
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gentamicin sulfate chemisorption by PAN fibres and by nonwoven ionexchange fabric based on PAN; and adhesion deposition of gentamicin sulfate on the surfw of nonwoven textile material, PP/viscose, with the help of polymer carrier- chitosan [20,22,23].
Dissolution studies In vitro, drug release was studied in the physiological solution (0.95% NaC1) and in phosphate-buffered saline. Gentamicin sulfate release fiom antimicrobial fibres was carried out by submerging the fibre-gentarnicin sulfate complex into a physiological solution (0.95% NaCl). After that, gentamicin sulfate release was monitored. Gentamicin sulfate release h m the fibre (physiological solution) was measured in vitro by a Shimadzu W-260 W-vis spectrophotometer. Releasing of bonded gentamicin sulfate has been studied in vitro, in physiological solution (0,95% NaCl), under the following conditions:
- physiological solution (0,95% NaC1);
-
desorption time: 1,5,10,15,30,45,60,120,1440 temperature of desorption: 25+ 2OC; pH of physiological solution: 7.0; and liquor ratio: 1:400.
min;
Skin penetration and gentamicin release fiom the antibiotic/polymer complexes was measured in vitro by Franz diffusion cell technique [26]. The gentamicin release was studied in 500 ml of phosphate-buffered saline (PBS, pH 7.4) at 370 C in a mild shaking environment (75-100 r.p.m.). Aliquots of 3 ml were assayed for gentamicin at the time points of 0, 0.25,0.5, 0, 75, 1,2,3,4, 5,6, 12 and 24 h. For assessment of the quantity of gentamicin sulfate released, HPLC (High-performance liquid chromatography) method has been used. Inhibition activity has been determined by diffusion method on agar plate. The antimicrobial efficiency of this bioactive transdermal system was examined on an agar plate seeded with indicator microorganisms (Staphiolococcus aureus ATCC2.5923, Echerichia coli ATCC2.5922, Pseudomonas Aergenosa ATCC9023, Candidia albicans ATCC2.592, Klebsiellapneumoniae ATCC4352). Samples were tested after 24 hours lasting incubation at 37OC by recording the presence or absence of visible colonies on the agar surface directly above the fibrous textile material. After visually inspecting agar surface, inhibition zone (bactericidal and bacteriostatic)was determined.
EXPERIMENTAL, RESULTS AND DISCUSSION The results of gentamicin sulfate quantities bonded by fibres and nonwoven materials are presented in Table 1. Depending on the antimicrobial textiles manufacturing procedure selected, fibres and nonwoven textile material were bonded using different quantities of gentamicin. From the data presented in Table 1, it is obvious that the greatest quantity of gentamicin was bonded on ion- exchange nonwoven material based on PAN fibres. Taking into account of the ion-exchange properties of the substrate, both chemical and physical bonding of gentiunicin on polymer matrix were carried out. 32
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Table 1. Quantity of bonded gentamicin sulfate by fibrous material
Type of fibrous material
Quantity of bonded gentamicin sulfate ____________~ 11OJ mg/g fibre Ion-exchange 112,3 mg/g fibre - PAN fibres 1 18,2 mg/b fibre 3.67 rnn/crn' Nonwoven ion-exchange 3.12 rngkrn' material based on PAN 2.77 rng/cm' 2.53 mg/crn' 1.0 mg/cm' Nonwoven material 0.9 mg/cm' PP/viscose 0.1 ing/cm' 0.09 rng/crn'- __ -~ _ _ ~
Desorption process develops slowly. It comprises a mdtistadium process and encompasses the following phases: diffusion of physiological liquid in polymer- carrier, swelling of polymer- carrier and increasing its porosity, breakage of primary and secondary bonds between gentamicin and polymer and, finally, diffiion of gentamicin molecules from polymer to the selected place in the organism. Figures 1-3 represents the kinetics of gentamicin sulfate release from antimicrobial textile obtained in physiological solution (Fig. 1.) and in Franz cell (Fig. 1,2 and 3).
Tme, min
-h
Figure 1. Cumulative amount of gentamkin released h m complex "PAN ion-exchange fibre - gentamicin sulfate"
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Figure 2. Cumulative amount of gentamicin released h m the complex "nonwoven PAN - gentmicia" obtained by chemisorption(Franz cell)
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6
2lPzl2#?6
Ihn;hrus
Figure 3. Cumulative amount of gentamicin released h m complex "gentamicinnonwovenPP/viscose"obtained by adhesion
Results of inhibitory activity of textile material treated with gentamicin sulfate are presented in Table 2 and in Fig. 4. Table 2: Inhibitory activity of nonwoven fabric test sample treated with gentamicin sulfate
; Time 5 min 10 min
15 min
E. coli
s.anmr
6 6, 5 7
10 10
P.
C.
9. 5
10. 5
10 10 7. 5
12 12 12
10. 5 10 10 9, 5 8, 5 6 5.5 3
30 min 60 min 120 min 24 h One month
5
7,5 9, 5 5.5 7, 5 3. 5 8 3, 5+2, 5 (d) 6 0, 8
4 4,s
4,5+2,5 (d)
10 8 7
Control sample
7
7,5
14, 5
11
11,5
From these results it is obvious that antimicrobial textile material demonstrates an inhibitory activity towards a l l indicatory microorganisms. The strongest effect is observed with P.Aeruginosa and C.Albicans. The widths of inhibition zones slightly decrease with the time the sample spend in physiological solution before application on selected strains of bacteria.
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E. Coli
S. Aureus
P.Aeruginosa
&lebsiCllo
C. Albicans
Fig.4. Inhibition of the growth of tested microorganisms treated with antimicrobial material "PP/viscose-gentamicin sufate 0,lmg/cm2", which spent 5, 10 and 15 min in physiological solution. It is just the reason why the widths of inhibition zones are bigger in control samples (samples which did not stand in physiological solution), with exception of indicatory strain Mebsiella. In this case the widths of inhibition zone in samples which dwelled in physiological 5,lO and 15 min are greater than those of control sample. The reason for such a phenomenon could be manifold. There is, before all, the question the diffusion of the active substance through the support (i.e. the weakening of the bond between textile and the preparation). The second reason could be the sensitivity of Klebsiella sp. on gentamicin sulfate concentrations, being attained on the borders of the inhibition zone. Starting from the Fickian law which describes d i f i i o n and fkom experimental results, a mathematical dependence of gentamicin release from antimicrobial band-aid (plaster) has been obtained in the following form:
y = a ( l - e q . .........................................................................................(1) where are: y-cumulative quantity of gentamicin sulfate released, k-the speed of releasing, t-time, a- parameter dependent on starting sample characteristics and desorption conditions. Fig. 5 and Fig. 6 show the models for samples obtained in different experimental conditions of antibiotic release.
---1
70-
y=60,67(leq""? ~=63,95(1e~~~)
9
y=66,07(le"."O")
A
0
2
0
4
o
I - ./ /
m
210
m
rimin
Figure 5. Mathematical model of gentamicin release from complex ,,gentamicin-nonwoven fabric PPIviscose'', obtained by adhesion of
Figure 6. Mathematical model of gentamicin release from complex ,,PAN ionexchange fibre - gentamicin sulfate", obtained by chemisorption
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On the base of mathematical model it is possible to calculated particular values of parameters a and k h m equation (1). It may be seen that this mathematical model shows a high degree of agreement with experimental results (correlation coefficient surpassing 0, 99, so that its use for prognosis of gentzunicin sulfate behavior after application could be highly recommended.
CONCLUSION Medical band-aids with immobilized gentamicin sulfate showed a large spectrum of intense antimicrobial activity towards gram (+) and gram (-) bacteria and fungi. It has been found that band-aids have a prolongated effect and a high activity even with concentrations of active substance lower than 0,l mg/cm2. On the basis of the kinetics of the release of gentamicin sulfate studied, a mathematical model describing the process of medicine release is obtained.This model can be used for prognosis of prolonged release of medical substance from band-aid as a transdermal system.
REFERENCES 1 S Rajendran, S C Anand, ‘Development of a versatile antimicrobial f i s h for textile materials for healthcare and hygiene application’, Proceedings of the 2nd Int Conf, Medical textiles, 24th t 25th August 1999, Bolton Institute, UK, Edited by Subhash h a n d , Woodhead Publishing (April 2000) 107-116. 2 L Wang, J Xie, L Gu, G Sun, ‘Preparation of antimicrobial polyacrylonitrile fibres: blending with polyacrylonitrile-co-3-allyl-5,5-dimethylhydantoin’,Polymer Bulletin, 2006 56(2/3). 3 www.swicofil.cod~rodu~O55chitosan.html
4 E Wilk, G Dyiworska, ‘Antimicrobial properties of silver content textiles’, 5* World Textile Conjirence A UTEX 2005, Portorof,Slovenia (June, 2005), Proceeding, p.267. 5 U Klueh, V Wagner, et all., ‘Efficacy of silvercoated fabric to prevent bacterial colonization and subsequent device-based biofilm formation’, Biomed Muter.Res, 2000 53(6) 621.
6 www.nsti.ore/Nanotech2005/showabstract.hto=198 7 E A Deitch., A A Marino, T E Gillespie, J A Albright, ‘Silver-nylon: a new
antimicrobialagent’, Antimicrobial Agents and Chemotherapy, 1983 23(3) 356, 8 www.blockemf.com/catalog/vroductinfo.DhD?uroducts id=5090
9 http://www.silverlon.Lcom/burn product descriptomhtml 10 D Parsons, P G Bowler, V Myles, S Jones, ‘Silver antimicrobial dressing in wound management: a comparison of antibacterial, physical, and chemical characteristics’, Woundr, 2005 17(8) 222. 11 www.aerrisasia.com/imDrovenonwovens.html 36
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12 httD://www.azonano.com/details.as~?ArticleID=3 16
1 3 www.fasebi.orp;/cgi/content/abstract/04-2029fie 14 Y Endo, T Tani, and M Kodama, ‘Antimicrobial activity of tertiary amine covalently bonded to a polystyrene fibre’, Appl Environ Microbiol. 1987 5 x 9 ) 2050-2055.
15 T N Yudanova, I V Reshetov, ‘Modern wound dressings: manufacturing and properties’, Pharmaceutical Chem .J 2006 40(2) 85-92. 16 T L Yurkshtovich, V A Alinovskaya, N S Butrim, D S Zimnitski, ‘Kinetics of antibiotic sorption by monocarboxyl cellulose’, ColloidJ, 2004 66(l) 100-105. 17 M Roby, Heterogeneous yams for surgical articles, US Patent Office, Pat No, 20050125036. 18 W Shalaby, Shalaby. ‘Antimicrobial fabrics’, US Patent Ofice, Pat No, 6780799. 19 J Buchenska, J Tazbir., ‘Antibacterial chinugical threads containing cephalosporine of forth generation’, Int ConfMEDTEx2005,39-43.
20 J Buchenska, ‘Pan fibres with antibacterial properties’, Fibres & Textiles in Eastern Europe, 1996 4(1) 53-59. 21 P Skundric, A Medovic, Lj Simovic, S Dirnitrijevic, M Kostic, M Janicijevic, B Milakovic, ‘Boimedical antimicrobial textile materials of broad spectrum activity’, V Int C o d MEDTEx2005 24-27. 22 P h u n d r i k , A Medovik, M Kostik, ‘Fibrous systems with programmed biologicalactivity and their application in medical practice’, AUTEXRes J, 2002 2(2) 78-84. 23 P Skundric, A Medovic, Lj Simovic, S Dimitrijevic, M Kostic, ‘Development and characterization of antibacterial bioactive fibres as W e d therapeutic systems’, 5th World Texrile Conf A U T . 2005, PortoroZ, Slovenia, June 27-29,Book 1, p.232, (2005). 24 T Mihailovic, K Asanovic, Lj Simovic, P Skundric, ‘Influence of an antimicrobial treatment on the strength properties of polyamide/elastane weft-knitted fabric’, J of Appl Polymer Ski, 2006 103(6) 4012-4019.
2 V M Varagic, and M P Milosevic, ‘Pharmacology (in Serbian), Elit-Medica, Belgrade (1 994). 26 C Goosen, et al., ‘A comparative study of an in situ adapted diffision cell and an in vitro Franz diffusion cell method for transdermal absorption of doxylamine’, Eur J Pharm Sci. 2001 13(2) 169-77.
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COlMPARISON OF ANTIMICROBIAL TEXTILE TREATMENTS E. J. Smith', J. T. Williams', S. E. Walsh' and P. Painte2 'Textile En 'neering and Materials Research Group,De Montfort University, Leicester, UK, Leicester School of Pharmacy, De Montfort University, Leicester, UK
P
ABSTRACT In recent years there has been an increase in the range of antibacterial textile based products available, especially in hygiene-sensitive sectors such as the health sector and the foodstuffs industry. These can range h m simple wipes to wound dressings and clothing applications. This increase in use has created a need for more microbiological data about the effectiveness of merent types of treated fabrics under a variety of conditions in which they may be used. Current standard test methods may not accurately reflect some of the in-use conditions. Using standard and amended test methods, commercially available textile products claiming antimicrobial properties were assessed against Staphylococcus aureus. Active ingredients of the treated antimicrobial textiles included silver, quaternary ammonium salts and triclosan. Fibres claiming antimicrobial properties such as bamboo and soy were also tested. The different silver treatments assessed were manufactured by the application of silver to the fabric as an after-treatment or inherent in which silver is added to the fibre during the spinning stage or coated on thread. The commercially available textiles were subjected to conditions ranging from wet, in which the samples were incubated in an aqueous bacterial suspension, to dry bacterial applications. This was to determine whether the antimicrobial activity of fabrics is a€€ected by differing moisture levels so that predictions of the in-use activity of commercially available antimicrobial textile based products can be made more accurately.The efficacy of the "treatments" is presented for the various product categories under different conditions of wetness which may have application in the clothing industry. INTRODUCTION In recent years there has been an increase in the range of antimicrobial textile based products available, especially in hygiene-sensitive sectors such as the health sector and the foodstuffs industry". These can range h m simple wipes to wound dressings and clothing applications. This increase in use has created a need for more microbiological data about the effectiveness of different types of treated fabrics under a variety of conditions and uses. Medical dressings are applied to wounds which are wet, but clothing is similar to the relative humidity of the room unless it is next to the skin and absorbing sweat. Current standard test methods may not accurately reflect some of the in-use conditions. Using standard and amended test methods, commercially available textile products claiming antimicrobial properties were assessed against StuphyZococcus aureus @. aureus). Antimicrobial textiles are usually manufactured either by the application of the antimicrobial agent to the fabric as an after-treatment finish or as an inherent treatment in which the antimicrobial agent is added to the fibre during the spinning process'. '. Active ingredients of the treated antimicrobial textiles tested included silver, quaternary ammonium salts and triclosan. Several different silver treated fabrics were 38 0 Woodhead Publishing Limited, 2010
assessed in which silver had been applied either as an after-treatment finish; as an inherent treatment; or as silver coated yamsd7 woven into the fabric. Fibres claiming antimicrobial properties such as bamboo and soy were also tested. The commercially available textiles were subjected to conditions ranging from wet, in which the samples were incubated in an aqueous bacterial suspension, to dry bacterial applications. This was to determine whether the antimicrobial activity of fabrics is affected by differing moisture levels so that predictions of the in-use activity of commercially available antimicrobial textile based products can be made more accurately. The efficacy of the "treatments" is presented for the various product categories under different conditions of wetness which may have application in the clothing industry.
MATERIALS AND METHODS Organisms
The Gram positive bacterium, S. aureus ATCC 6538 was used in all experiments.
Fabrics Various commercially available textiles claiming antimicrobial activity were examined (Table 1). Active ingredients of the treated antimicrobial textiles included silver, quaternary ammonium salts (QACs) and triclosan. The textile substrates for the treated samples were polyester or a polyester/ cotton blend. Fibres claiming antimicrobial properties such as bamboo and soy were also tested. Relevant untreated fabrics were examined as control samples. Table 1 Composition of the antimicrobialfabrics used in this study Material Polyester (50%) / cotton (50%) blend Polyester (50%) /cotton (50%) blend Polyester (50%) /cotton (50%) blend Polyester (98%) / silver coated thread (2%) Polyester (67%) I cotton (33%) blend Polyester (50%)/ cotton (50%) blend Triclosan - inherent Polyester (50%) /cotton (50%) blend Bamboo - regenerated fibre Bamboo (1 00%) Bamboo (60%) / Cotton (40%) blend Carbonised bamboo Carbonised bamboo / polyester composite - soy soy (100%) :Finish type A is a very fine colloidal suspension of silver tFinish type B is a microparticle composite of titanium dioxide containing soluble silver chloride *Silver coated threads woven as uniform stripes (approx 5mm apart) on polyester fabric visible on one or both sides 'Quaternary ammonium salt Antimicrobialagent Silver - after-treatment finish type A' - after-treatmentfinish type Bt - inherent Silver coated thread* QAC' - tinish
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Test methods Three different standard quantitative test methods were chosen to evaluate the antibacterialproperties of the chosen commercially available textiles. These represented conditions from soaking wet to dry bacterial application.
AA TCC 100-2004 Assessment of Antibacterial Finishes' All samples were initially tested in duplicate using AATCC 100-2004,to evaluate the degree of antibacterial activity. This standard test is a quantitative test where the fabric absorbs a set amount of a bacterial suspension, it therefore provides moist conditions. The standard test time for incubating the inoculated fabrics is 24 hours, but in these tests a shorter incubation time of 6 hours, closer to the period of a working shift, was also undertaken. A 24 hour nutrient broth culture of S. aureus was diluted with sterile nutrient broth to give a final concentration of 1-2x los colony forming units (CFU) per ml. Sterilised circular swatches of each fabric measuring 4.8 cm in diameter were placed in a sterilised 250 ml glass jar. 1 ml of the diluted bacterial suspension was applied to each fabric swatch, ensuring even absorption. The jars were sealed and incubated at 37 "C for different contact periods; 0 hours, 6 hours and 24 hours. After incubation, 100 d of sterile distilled water was added to each jar and shaken for 1 minute. Serial dilutions were performed and were plated on nutrient agar using the Miles Misra method'. The plates were incubated for 24 hours at 37 "C and the number of CFU / fabric was calculated. The antimicrobial activity of the tested fabric samples was expressed as a log reduction, in which the mean log10 density of bacteria recovered fkom the inoculated test sample over a 6 or 24 hour contact time was subtracted from the mean log10 density of bacteria of that test sample immediately after inoculation (0 hours contact time). ASTM E2149-01 Standmd Test Method for Determining the AntimicrobialAgents under Dynamic Contact Conditions" To represent soaking wet conditions, the antimicrobial properties of specific test samples were evaluated in duplicate using ASTM E2149-01 (Dynamic Shake Test). This is a quantitative method where samples are incubated in an aqueous bacterial suspension under constant agitation to ensure good contact between the bacteria and the treated fabric". The standard states a contact time of 1 hour, but 24 hour contact time was also performed to see the efficacy over longer periods and to compare with the results from other test methods. A 24 hour nutrient broth culture of S. aureus was diluted with sterilised 0.3 mM phosphate buffer to give a final concentration of 1-2 x lo5 CFU / ml. 50 ml of the diluted bacterial culture was transferred to sterilised 250 ml glass jars to which 1.O g of test fabric, which had been cut into approximately 1 cm2 pieces then autoclaved, was added. The tops were screwed onto the jars and they were incubated and shaken at 120 rpm at 37 "C for 1 hour or 24 hours. After incubation, serial dilutions were performed and were plated onto nutrient agar using the Miles Misra method. The plates were incubated for 24 hours at 37 OC and the number of CFU / g of fabric was calculated. The antimicrobial activity of the tested fabric samples was expressed as a log reduction in which the mean log10 density of bacteria for the jar containing the test samples after 40
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incubation over 1 or 24 hours was subtracted from the mean log10 density of bacteria for the jar prior to the addition of the test samples.
J E L1902:2002 Testingfor antibacterial activity and eflcacy on textile products" To investigate the antimicrobial properties of the test samples when exposed to bacteria by dry contact, an amended form of the printing method JIS L1902:2002 was used. The test was adapted so that a variety of heat and humidity conditions could be emulated, by conditioning the test samples printed with bacteria in desiccators at a set relative humidity and temperature. A range of contact periods was chosen. A 24 hour incubated test culture of S. aureus in nutrient broth was diluted with sterile nutrient broth to give a final concentration of 1-2 x lo5 CFU / ml. A sterilised 0.2 p membrane filter was placed in a Millipore filtration unit and 5 ml of sterile distilled water was poured on the filter followed by 2 ml of the diluted test inoculum. Filtration was carried out under reduced pressure (via a vacuum pump) and was maintained for 1 minute after the liquid had disappeared from the membrane filter. The membrane filter was then placed on the rotating table of the printing system with the bacteria coated surface facing uppermost. A test fabric sample, which had been cut into a circular swatch of 4.8 cm in diameter and autoclaved, was placed on top of the membrane filter. A silicone coated plate was placed on top of the fabric sample and a 4 N load was applied. Bacteria were printed onto the test fabric sample by rotating the rotating table by 180" in one direction over 3 seconds. The printed test fabric was removed for immediate shaking out in the case of the 0 hour sample or for incubation over different contact periods. For immediate shaking out, the printed fabric was laced into a glass jar containing 20 ml of sterilised water or appropriate neutraliserlg 13. The triclosan treated fabrics were neutralised using 30 g/l Tween 80 (polysorbate), while the QAC treated fabrics were neutralised using a mixture of 30 g/I Tween 80 and 3 gA lecithin. No neutraliser was used for the silver samples. The glass jar was then shaken using a vortex mixer 5 times for 5 seconds each. For incubation over different contact periods the printed fabric was placed in a desiccator conditioned to a temperature of 25 "C and a relative humidity of either 99% with a saturated solution of di-sodium hydrogen phosphate dodecahydrate or 10% with calcium chloride powder for 1 hour, 4 hours or 24 hours before shaking out. The relative humidity of the conditioned environment was monitored using an rH meter. After shaking out, serial dilutions were performed using sterile distilled water and plated onto nutrient agar plates using the Miles Msra method. The plates were incubated at 37 "C for 24 hours and the number of CFU present was recorded. All samples were tested in triplicate. The antimicrobial activity of the tested fabric samples was expressed as log reductions, calculated by two methods: 1) by subtracting the mean log10 density of bacteria recovered from the inoculated test samples at 1 , 4 or 24 hour contact time from the mean log10 density of bacteria of that test sample immediately after 0 hours contact time; 2) by subtracting the mean log10 density of bacteria recovered from the treated samples at each time point h m the mean log10 density of bacteria recovered from the control fabric at that time point.
RESULTS AND DISCUSSION The log reduction results for each of the fabrics when tested under moist conditions using AATCC 100 are shown in Table 2. Samples treated with QACs or triclosan showed a reduction in bacterial growth after both 6 hours and 24 hours. For the silver treated samples, a reduction in bacterial growth was observed for the samples which 0 Woodhead Publishing Limited, 201 0
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were treated with silver as an &-treatment (finishes A and B), but no reduction in growth was observed for the inherent silver or silver coated thread samples. This should be expected, as silver requires the presence of an aqueous environment to readily ionise and become active'4*Is. If the silver is on the surface, as with the after-treated products, the silver should have sufficient contact with water to ionise and be effective; this is not the case for inherent silver roducts where the silver is trapped in the mtre of the fibre where it is not functional'. Although the triclosan sample tested is also inherent, a similar effect was not observed as triclosan migrates to the surface'. It should be noted that when the fabric containing silver coated thread was tested with the silver face down a slight reduction in bacterial growth occurred after 6 hours, but this was not observed when the sample was tested with the silver face up. After 24 hours there was an increase in bacterial growth with both the silver face up and the silver face down. This would suggest that after 6 hours there was sufkient moisture on the base of the container used to test the fabric for the silver to come into contact with it and ionise, but after 24 hours the moisture levels may have been too low for this to occur. The 100% bamboo showed a reduction in bacterial growth after 6 hours incubation, but no reduction in growth was seen after 24 hours. The 60% bamboo, 40% cotton blend showed an increase in bacterial growth. This suggests that there may have been insufficient bamboo fibre in the blend to have any antibacterial effect and supports previous claims that state that to be antimicrobial there must be greater than 65% bamboo content17. Carbonised bamboo on polyester showed no antimicrobial activity. The soy fibre showed only minimal antimicrobial activity after 6 hours. The unkated control samples all showed an increase in the number of organisms with 100% cotton having a larger increase in bacterial growth than 100% polyester. The higher the cotton content in cotton polyester blends, the higher the level of bacterial growth was recorded. This could be expected, as generally natural fibres are more susceptible to bacterial growth than synthetic fibres'*. This is due to natural fibres, like cotton, having higher level moisture retention than synthetic fibres like polye~ter'~. Bacteria prefer warm humid conditions to gmdp19, so higher moisture content in a fabric will encourage higher bacterial growth. Table 2. Log reduction results, calculated by comparison with time zero, for S. aureus using AATCC 100: 2004 on a range of fabrics Sample
Log reduction (standard deviation) 6 hours 24 hours
QAC* 67% polyester 133% cotton Triclosan 50% cotton I50% polyester Silver after-treatment finish A* Silver after-treatment finish B* Silver - inherent 50% polyester I50% cotton Silver coated thread / polyester both sides Silver coated thread / polyester single side: Face up Face down Bamboo (100%) Bamboo (60%)1 Cotton (40%) Carbonised bamboo/ polyester soy (1 00%) Cotton (100%) 42
0.80 (0.71) 0.68 (0.46) >1.38 0.54 (0.71) -2.93 (0.08) -0.98 (0.04) -1.29 (0.18) 0.08 (0.08) 1.84 (0.02) -0.93 (0.04) -2.72 (0.16) 0.30 (0.24)
---
1.66 (0.02) >1 .60t 1.33 (0.21) 0.51 (0.06) -3.935 (0.22) -2.55 (0.18) -1.70 (0.16) -1.68 (0.06) -0.33 (0.06) -2.17 (0.06) -2.75 (0.33) -2.75 (0.02) 4.58 (0.11)
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Polyester (50%) / Cotton (50%) -2.83 (0.08) -3.83 (0.12) Polyester (67%) I Cotton (33%) -1.3 1 (0.08) -2.72 (0.33) Polyester (1 00%) -0.80 (0.28) -2.57 (0.10) *Quaternaryammonium salts. 'Decrease in bacterial numbers greater than the l i t of sensitivity. %O% cotton J 50% polyester. %crease in bacterial numbers.
To determine whether the inherent silver and silver coated thread samples would show antimicrobial activity when subjected to soaking wet conditions, the dynamic shake method, ASTM E2149, was performed. The log reduction results after 1 hour and 24 hours incubation at 37 "C (Table 3) show that under soaking wet conditions the inherent silver and silver coated thread samples do exhibit a reduction in bacterial growth. The untreated control samples show an increase in bacterial growth. From these results it would appear the antibacterial activity of inherent silver and silver coated thread samples require soaking wet conditions to exhibit their antibacterial properties. As with the AATCC 100 method, the carbonised bamboo sample showed no antimicrobial activity. Table 3. Log reduction results, calculated by comparison with starting inocdum for S. aureus using ASTM E2149-0 1 on a range of fabrics Sample
Log reduction (standard deviation) 1 hours 24 hours Polyester (1 00%) -0.41* (0.42) -2.53 (0.04) Polyester (50%) I Cotton (50%) -0.26 (0.02) -0.63 (0.16) Silver after-treatmentfinish A 100% polyester >1.91t 0.41 (0.03) Silver - inhmnt 50% polyester 150% cotton >1.92 0.79 (0.04) Silver coated thread / polyester (double sided) 0.56 (0.27) 1.26 (0.24) Silver coated thread / polyester (single sided) >1.91 0.91 (0.23) Carbonised bamboo1 polyester -0.09 (0.01) -3.98 (0.12) *negative figures indicate an increase in bacterial numbers. 'indicates a decrease in bacterial numbers greater than the limit of sensitivity of the test. The dry application of bacteria on treated and untreated fabric was tested using an amended form of the print method (JIS 1902:2002), so that environmental conditions such as relative humidity and temperature could be set and monitored. Initial work looked at 99% rH conditions with a temperature of 25 "C. These conditions were chosen as it was assumed that the treated samples would be more likely to show activity at a high relative humidity thus proving whether this was a feasible method to use. If treated fabrics showed activity in these conditions, lower relative humidities would be examined. The temperature was chosen to represent room temperature of the service environmentswhere these fabrics may be used. Results for the fabrics tested using the printed method were expressed as log reductions, initially these were calculated by subtracting the mean log10 density of bacteria recovered from the inoculated test samples at 1 , 4 or 24 hour contact time from the mean log10 density of bacteria on test samples after 0 hours contact time. The results for 99% rH and 25 "C test conditions using appropriate neutralisation (Table 4) showed log reductions in both the treated and untreated test fabrics. The reduction in bacterial numbers on the untreated fabric would suggest that there is some bacterial 0 Woodhead Publishing Limited, 2010
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death by desiccation occurring. To establish the extent to which the reduction on the treated samples were due to the antibacterial finishes, the log redudion was calculated by subtracting the mean log10 density of bacteria recovered from the treated samples at each time point from the mean log10 density of bacteria recovered from the untreated control fabric at that time point (Table 5). The silver treated samples did not appear to have any significant effect on bacterial numbers, even though a neutraliser was not used. This would have led to an over estimation not an under estimation of any efficacy shown.The triclosan treated samples did not appear to have a significant effect on the bacterial numbers when neutralisation was employed. The results for the QAC on a 50% polyester 50% Cotton blended fabric showed a large standard deviation at 0 , l and 4 hours incubation but &er 24 hour a log reduction of greater than 1 was achieved consistently. The results for the QAC on a 67% polyester 33% cotton blended fabric did not appear to have a significant effect. Centrifugation of the cultures before printing did not adversely affect bacterial survival, as similar results for all samples tested were achieved wben the printing procedure was pedormed without centxifigation (data not shown). Removal of the neutralisation step did not improve the log reductions recorded for any of the samples, suggestingthat the antibacterial finishes were not being released into the resuspension solution (data not shown). This may be advantageous for some applications, as it points towards the durability of the finishes. Table 4. Log reduction results, calculated by comparisonwith time zero, for S. aureus using amended ns L-1902 using appropriate neutralisationa range of fabrics at 99% rH Log reduction (standard deviation) Sample lhr 4hr 24hr QAC* 67% polyester 133% cotton 1.65 (1.63) 0.45 (0.40) 1.37 (2.74) QAC SOYOpolyester I 50% cotton 1.46 (1.45) 0.40 (1.82) 2.18 (2.63) Triclosan 50% cotton I 5oOh polyester 0.45 (0.68) 0.52 (0.05) 1.10 (0.30) silver after-treatmentfinish A+ 0.44 (0.36) 1.19 (1.21) 2.24 (0.67) Silver after-treatmentfinish Bt 1.22 (1.16) 0.82 (0.52) 2.10 (0.51) 67% polyester I 33% cotton 1.33 (1.79) 0.26 (0.24) 1.74 (2.20) 500?polyester I 50% cotton A 0.70 (0.17) 0.52 (1.02) 1.60 (0.87) W ?polyester I 50% cotton B 0.86 (0.92) 0.72 (0.38) 1.37 (1.16) Quaternary ammonium d t . 'neutralisation not used, 50% cotton I 50% polyester. Table 5. Log Reduction results, calculated by comparison with the control, for S. aureus using amended JIS L-1902 using appropriate neutralisationa range of fabrics at 99?hrH Sample Log reduction (standard deviation) Oh lhr 4hr 24hr QAC* 67% polyester I 33% 0.12 (0.1 1) 0.43 (0.53) 0.3 1 (0.27) -0.26T(0.92) cotton QAC 50?hpolyester I 50.41 0.64 (2.04) lAO(O.98) 0.52(0.81) 1.22(0.29) Cotton
0.03 (0.40) -0.38 (0.52) -0.17 (0.29) -0.23 (0.11) Triclosan 500h cotton I 50% polyester Silver after-treatment finishA* -0.78 (0.46) -1.04 (0.28) -0.12 (1.02) -0.14 (0.54) Silver after-treatmentfinish B* -0.23 (0.89) 0.29 (1.30) 0.06 (1.82) 0.27 (0.14) *Quaternary ammoniumsalt. 'Negative figures indicate an increase in bacterial numbers in comparison to the control at that time point. *Neutralisationnot used, 50% cotton I 50% polyester. 44
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Control experiments were conducted in duplicate to investigate the survival of S. aureus at high, loo%, and low,
’.
Table 6.Log reduction results, calculated by comparison with time zero, for S. aureus using amended JIS L-1902 on untreated cotton and polyester fabrics at high and low rH Sample
% Relative humidity
100%cotton
100%polyester
4 0 100
Log reduction (standard deviation) lhr 4hr 24hr 0.46 (0.42) 0.48 (0.41) 0.75 (0.39) 1.00 (0.43) 0.68 (0.24) 0.50 (0.34) 0.54 (0.77) 1.21 (0.65) 1.91 (0.54) 0.42 (0.22) 0.76 (0.36) 0.97 (0.39)
CONCLUSIONS This study shows that the activity of an antimicrobialtreated fabric varies depending on the test conditions used. This could be helpful in determining the end use of a treated fabric. Treated fabrics examined in this study containing triclosan, QACs or silver as an after-treatmentproved to be active in moist conditions. Fabric containing inherent silver or silver coated thread required soaking wet conditions. This is fine if the treated fabric is to be used in an environment which is wet such as wound dressings, where silver is currently the antibacterial of choice, as the presence of wound fluids or other secretions ionise the silver to its active f01-m’~. Previous studies have investigated the microbial contamination of textiles used in hospitalszo* and the potential for transfer by contac?. To address this problem, antimicrobials are being applied to outer clothing or textiles for hospital use such as gowns, scrubs, nurses’ uniforms, bedding or curtains. The aqueous conditions used in standard tests such as AATCC 100 and ASTM E2149 do not reflect these ‘real-life’ clinical environments. Dry application conditions such as the printing method of JIS 1902 can be adapted to take into account environmental factors such as temperature and humidity and may be a more accurate way of assessing the efficacy of treated fabrics to be used in clinical environments. From the results gathered in this study, dry application showed no significant decrease in bacterial growth when compared with controls. This would suggest that treated fabrics may be of limited value for textiles in non aqueous environments such as outer garments and curtains, but may be of use if textiles are in intimate contact with the skin absorbing sweat such as for undergarmentsor socks.
ACKNOWLEDGEMENTS The authors would like to acknowledge a ‘Students into Work’ grant to P. Painter from the Society for Applied Microbiology. 0 Woodhead Publishing Limited, 201 0
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REFERENCES 1 T Ramachandran, K Rajendrakumar and R Rajendran, ‘Antimicrobial Textiles- and Overview’, IE(4 Journal-TX, 2004 84 42-47. 2 H Struszczyk, J Lebioda, K Twarowska-Schmidt and A Niekraszewicz, ‘New Bioactive Synthetic Fibres Developed in The Institute of Chemical Fibres’, Fibres and Textiles in Eastern Europe, 2003 ll(2) 96-99. 3 G Sun and S D Worley, ‘Chemistry of Durable and Regenerable Biocidal Textiles’, Journal of Chemical Education, 2005 82(1) 60-64.
4 K Takai, T Ohtsuka, Y Senda, M Nakao, K Yamamoto, J Matsuoka and Y Hirai, ‘Antibacterial properties of antimicrobial-finished textile products’, Microbiol. Immunol., 2002 46(2) 75-81. 5 G Salvio, ‘A new polyester fibre with antibacterial activity’ 39‘ International Man Made Fibres Congress, Dorbin, Austria 2000. 6 E A Deitch, A A Marino, T E Gillespie and J A Albright, ‘Silver-nylon: a new antimicrobial agent’, Antimicrobial Agents and Chemotherapy, 1983 W(3) 356-359.
7 P C MacKeen, S Person, S C Warner, W Snipes and S E Stevens, ‘Silver-coated nylon fiber as an antibacterial agent’, Antimicrobial Agents and Chemotherapy, 1987 31(1) 93-99. 8 ATCC Technical Manual, AATCC Test Method 100-2004,Antibacterial Finishes on Textile Materials: Assessment of;North Carolina 2005.
9 C H Collins, P M Lyne and J M Grange, Collins and Lyne’s Microbiological Methodr, 7m edn, Oxford, Butterworth-Heinemam, 1995. 10 h u a l Book of ASTM Standards V 11.05, ASTM E2149-01, Standard Method for Determining the Antimicrobial activiw of Immobilized Antimicrobial Agents Under Dynamic Contact Conditions, Pennsylvania 2005. 1 1 JIS L 1902:2002, Testingfor antibacterial activity and eflcacy on textile products, Tokyo 2002.
12 A D Russell, ‘Factorsinfluencing the eficacy of antimicrobial agents’ Russell, Hugo and Aylrye s Principles and Practice of Disinfection, Preservation and Sterilization, edn, A P Fraise, P A Lambert and J-Y Maillard (eds), Oxford, Blackwell Publishing, 2004. 13 BS EN 1276:1997, Chemical disinfectants and antiseptics - Quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food industrial, domestic, and institutional areas - Test method and requirements (phase 2, step I), London 2002.
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14 B S Atiyeh, M Costagliola, S N Hayek and S A Dibo, ‘Effect of silver on bum wound and infection control and healing: Review of the literature’, Burns, 2007 33 139148.
15 B Gibbins and L Warner, ‘The role of antimicrobial silver nanotechnology’ Medical Device and Diagnostic Industry Magazine, 2005 27(8) 6. 16 B Clemo, ‘Ultra-fresh silpure - A new generation of antimicrobials’ International Dyer, 2005 190(5) 33-35. 17 Litrax, ‘Bambootechnology’ www.litrax.com 18 M Montazer and M G Afjeh, ‘Simultaneousx-linking and antimicrobialfinishing of cotton fabric’, Journal ofApplied Polymer Science, 2007 103 178-185. 19 M A Taylor, Technology of Textile Properties, 3d edn, London, Forbes Publications, 1990.
20 A N Neely and M P Maley, ‘Survival of Eterococci and Staphylococci on hospital fabrics and plastic’, Journal of Clinical Microbiology, 2000 38 724-726. 21 C Perry, R Marshall and E Jones, ‘Bacterial contamination ofuniforms’, Journal of Hospital Infection, 2001 48 238-241. 22 S A Sattar, S Springthorpe, S Mani, M Gallant, R C Nair, E Scott and J Kain, ‘Transfer of bacteria from fabric to hands and other fabrics: development and application of quantitative method using Staphylococcus aureus as a model’, Journal of Applied Microbiology, 2001 90 962-970.
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EVALUATION OF PLASMA-DEPOSITEDANTI-ADHESIVE AND ANTI-BACTERIAL COATINGS ON MEDICAL TEXTILES A. J. Paul, F. Bretagnol, G. Buyle, C. Colin, 0. Lefranc, H. Rauscher CSMA Ltd,CERAM Research, Queens Road, Stoke-on-Trent, UK (Project ACTECO - European FP6 Project No. 515859-2, www.acteco.org)
ABSTRACT
X-ray Photoelectron Spectroscopy ( X P S ) and Time-of-Flight Secondary Ion Mass Spectrometry (ToFSIMS) are well established methods for the chemical characterisation of surfaces. The techniques combine well, where the quantitative elemental and chemical state information provided by X P S compliments the chemical and molecular structure information provided by ToFSIMS. The techniques probe only from the outermost few nanometres, which define and control the surface properties of many materials. Key developments in both techniques in recent years, including chemicdmolecular imaging, have resulted in a wider range of applications. Manufacturersand suppliers of both commercial and technical textiles are now exploiting these techniques, as ideal tools to aid the development and optimisation of the types of coating/treatment demanded by industry and consumers. Medical grade polyester and polypropylene fabrics have been functionalised using both low pressure and atmospheric pressure plasmas. Diethyleneglycol-dimethylether has been plasma-deposited in order to produce PEG-rich fabric surfaces (PEG = polyethyleneglycol) which are more resistant to the adhesion of proteins, cells and bacteria Octadecyldimethyl-(3-trimethoxysilylpropyl)-ammonium-chloride has been plasma-deposited to produce coatings which will kill bacteria on contact with the fabric surface. This work will demonstrate the suitability of X P S and ToFSIMS for the evaluation of these coatings. PLASMA TREATMENT OF TEXTILES The application of low pressure and atmospheric pressure plasmas for the functionalisation and coating of textile surfaces (and other materials) is growing in importance. Compared to some current commercial 'ket chemistry" processes, plasmas have numerous advantagesincluding: 0
Reduced usage of water, solvents, chemicals (including toxic compounds). Reduced energy consumption. Reduced waste/hazardousproducts.
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Controllable highly specific reactions (often involving a single-step process) for tailored, often innovative, surface engineering.
As regards new textile products, key areas of plasma process activity include: 0
Production of repellent surfaces to prevent/limit the adhesion of biofilmshacteria e.g. for surgical and hygiene applications. 48 0 Woodhead Publishing Limited, 2010
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Production of anti-bacterial coatings which will kill bacteria on contact with the fabric surface e.g. for clothing (casual, medical, sportswear) and hygiene (e.g. medical wipes/equipment).
The application of surface analysis techniques for coating development and optimisation are illustrated in the following examples.
X-RAY PHOTOELECTRON SPECTROSCOPY (XPS) In X P S (see Fig. l), a solid sample is irradiated with soft X-rays resulting in the emission of electrons (photoelecrrons) from atoms at/close to the sample surface. The measured photoelectron kinetic energies are diagnostic of the specific atoms which constitute the sampled depth (< 10 nanometres), since each atom in the periodic table is characterised by a unique set of electron energy levels. From the X P S spectrum @lot of photoelectron intensity vs. kinetic energy, where the latter is usually converted to orbital binding energy), the surface composition may be calculated (usually expressed in atomic percent, At?h).
Soft X-rays in
1
Element Identification (except H, He) Chem ical/Oxidation States @an titative Surface Specific Imaging/Mapping Complements ToFSIMS
Electrons out
Solid Sample
1
Fig 1. XPS - The Technique The photoelectron peaks in the X P S spectrum are not only characteristic of the elements from which they originate, but they also provide chemicdoxidation state information. The latter is revealed by small changes in binding energy (chemical shijZs) due to the influence of different chemical environments on the electron energy levels of an atom. W S is sensitive to all elements, except H and He, with a detection limit of ca. 0.1 At.% (1000 ppm). Overall, X P S provides quantitative elemental and chemidoxidation state infomation from the outermost few nanometres (surface) of a solid material. Quantitative elemental and chemicaYoxidationstate mapping by X P S can also be carried out, with a spatial resolution of less than 10 microns. This imaging tool, in combination with the spectra, is proving valuable for the evaluation and optimisation of coating coverage/uniformityon material surfaces. Polymer meshes, such as polypropylene and polyester, are used for the repair of hernias and other soft tissue defects. Whereas the use of mesh material has lead to a widely accepted improvement in this kind of surgery, their implantation can be associated with serious infection rates. In order to reduce the infection rates of such meshes, their surface properties have to be improved. 0 Woodhead Publishing Limited, 2010
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X P S is currently being used to study the low pressure plasma deposition of diethyleneglycol-dimethyl-ether (DEGDME, CH3OCH2CH2OCH2CH2OCH3)on meshes. The aim is to produce a stable PEG-rich surface (1,2; where PEG = polyethyleneglycol)which is repellent to biomolecules and cells (anti-adhesive/anti-jbuling),thus enhancing their biological integration. The coating is applied using DEGDME vapour in argon, using a capacitively coupled radio frequency system described elsewhere (1). In the XPS spectra, the plasma-deposited DEGDME coating is detected in the survey (elemental) and chemidoxidation state spectra. Examples of the latter are shown in Figure 2, whereby the C-0 rich DEGDME coating (Fig. 2b; C 1s binding energy = 286.5 eV for carbon in the C-0 chemical state) contrasts with the C-C dominated untreated polypropylene mesh (Fig. 2%C 1s binding energy = 285.0eV for carbon in the C-C chemical state).
a
G C p
-
292 290 288 286 284 282
Binding Energy (ev) L
i
Fig 2. C 1s X P S spectrum for a) untreated polypropylene mesh, b) - d) DEGDME coatings deposited with increasing plasma power.
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The DEGDME coating coverage and integrity can be quantified as a function of the plasma treatment parameters. This is illustrated by the change in the DEGDME coating composition with increasing plasma power (Figs. 2b - 2d), whereby the loss of desired C-0 character can be measured. Thus, XPS can help to optimise the DEGDME coating (Fig. 2b in this case) for maximum anti-adhesive properties. The technique can be further used to assess, for example, the effects of stmilisation (i.e. autoclaving, gamma irradiation, ethyleneoxide) or packagmghtorage on the integrity of the DEGDME coating.
Fig 3. XPS chemical state image (C 1s) of plasmadeposited DEGDME coating on 3D polypropylene mesh: light regions = good coating coverage, dark regions = poor coating coverage. Image dimensions = 0.8 mm x 0.8 mm. In tandem with the spectra, X P S imaging is important for assessing coating coverage. This is illustrated in Fig. 3 for a region of plasma-treated polypropylene mesh where the DEGDME coating is incomplete. The coating of surgical meshes and other three-dimensional substrates represents a challenge for the plasma technologists. Surface analysis techniques are playing an important role in the developments.
TIME-OF-FLIGHTSECONDARY ION MASS SPECTROMETRY (ToFSIMS) In secondary ion mass spectrometry (seeFig. 4), a sample is bombarded with a primary beam of ions. Positively and negatively charged secondary ions are emitted from the sample surface and these are mass analysed to produce mass spectra and images. The technique, as a mass spectrometry, provides detailed surface chemical information; elements, chemical groups, molecules, polymer groups. In Time-of-Flight SIMS (ToFSIMS), the primary ion beam is pulsed to produce packets of primary ions. Each primary ion packet impacts the sample surface and generates a packet of secondary ions at a well-defined point in time. These secondary ions are then accelerated to the same kinetic energy by the use of an extraction field. For the same kinetic energy, 0 Woodhead Publishing Limited, 201 0
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secondary ions of different mass will have different velocities and, therefore, different flight times through the mass analyser to the time-sensitive detector.
> All Elements detected
Primary Ion Beam in \
\
/
\.
> Detailed Chemical Structure
Secondary Ions out d
/
I+
> > >
Information; elements, functional groups, polymer groups, molecules Surface Specific Imaginghdapping Semi-Quantitative Complements X P S
Fig 4. ToFSIMS - The Technique
ToFSIMS analysis can be carried out routinely under stutic conditions, using such low primary ion doses that the sample is effectively undamaged by the analysis. This is particularly important for organic/polymer materials which are susceptible to ion beam damage. The mechanisms of secondary ion emission from the surface are also a key factor in producing data with a high level of chemidmolecular structure information,some of which correspondsto soft ionisation processes. Overall, static ToFSIMS spectra (plots of secondary ion intensity vs. mass-to-charge ratio, where the charge z = 1 for most species) are often representativeof the pristine surfice. ToFSIMS is highly surface sensitive where, in the stutic regime, the sampling depth is < 5 nanometres. ToFSIMS is generally more sensitive than X P S but it is not quantitative. Its chemical specificity, however, may be exploited in a semi-quantitative manner where variations in the surface concentrations of different chemical species may be followed by monitoring changes in relative signal intensities. Imaging by ToFSIMS is carried out by rastering a micro-focussed primary ion beam over the sample surface and collecting data at each position. Typically, a sample area is scanned such that a mass spectrum is acquired and stored at every pixel which defines the field of view (say, 256 x 256 pixels). Retrospectively, for any peak in the mass spectrum (or sum of peaks - for improved image statistics), an image can be generated. ToFSIMS imaging can be carried out with a spatial resolution down to 1 micron or less. As an imaging technique, ToFSIMS has been l i i t e d by the intensities of those signals which are, structurally, the most significant i.e. polyatomic clusters including molecular ions. With the more established ion sources such as gallium (Ga?, the intensities of these diagnostic signals are often too weak for chemicaYmo1ecular imaging. This is due to insufficient yields of these secondary ion species under light atomic primary ion bombardment. This problem has now been overcome by the use of heavy polvatomic/cluster primary ion sources such as bismuth (e.g. Bin?, which has resulted in dramatic increases in the yields of secondary ions needed to produce images (3). As such, ToFSIMS is now being more widely exploited for imaging material surfaces, including textiles.
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ToFSIMS (with X P S ) is currently being used to study the deposition of commercially available akyl-ammonium chlorides @.C1? onto polyester fabric (i.e. PET = polyethylene-terephthalate),in order to produce coatings which will kill bacteria on contact with the fabric surface. In addition to being functional, the coatings have to be durable and able to survive multiple washes in many cases (i.e. clothing). The use of atmospheric pressure plasma systems (e.g. in air or nitrogen) are currently being investigated. In one system, the liquid precursor containing the anti-bacterial agent is nebulised on the polyester fabric, either during the plasma treatment or postplasma. The aim is to optimise the treatment conditions to produce an effective and durable anti-bacterial coating. In tandem with XPS, ToFSIMS is being used to evaluate the coatings as a function of the plasma treatments. The sensitivity of ToFSIMS as a surface mass spectrometry is illustrated in Fig. 5, whereby specific signals characteristic of the anti-bacterial agent can be detected and differentiated from the PET substrate signals. This specificity to chemical and molecular structure can then be exploited in imaging mode.
(m
Xl
d
1.6
PET
1.4
1.2
0.6 0.4
0.2
x ld
3.6
R4N+ R4N+
Fig 5. ToFSIMS spectra of anti-bacterial (R4mcoating on polyester fabric (bottom) vs. untreated polyester fabric (top).
The application of ToFSIMS as a surface imaging technique is demonstrated in Fig. 6, where a commercially available anti-bacterial agent has been deposited onto polyester fabric 0 Woodhead Publishing Limited, 2010
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under different atmospheric plasma conditions. The ToFSIMS images show the coverage and distribution of the anti-bacterial coating on the fabric surface as a function of different process conditions - with good coverage for one set of conditions. As such, ToFSIMS (often in combination with XPS) is a useful tool for procesdcoating optimisation. Coating durability can also be studied by these techniques, as a function of, for example, washing (e.g. time, temperature, detergents, wash cycles) and ageing (e.g. shelf life, exposure to ultra-violetlsun).
anti-bacterial coating (light regions) on polyester fabric Fig 6. Plasma depositions of using four different plasma process conditions; best coverage = bottom right. Image dimensions= 5 mm x 5 mm.
REFERENCES 1 F Bretagnol, M Lejeune, A Papadopoulou-Bouraoui,M Hasiwa, H Rauscher, G Ceccone, P Colpo and F Rossi, ‘Fouling and non-fouling surfaces produced by plasma polymerisation of ethylene oxide monomer’, Acta Biomaterialia, 2006 2 165-172. 2 E E Johnston, J D Bryers and B D Ratner, ‘Plasma Deposition and Surface Characterisation of Oligoglyme, Dioxane and Crown Ether Nonfouling Films’, Langmuir, 2005 21 870-881.
3 A J Paul, ‘Organic and molecular imaging by ToFSIMS - at the cutting edge’, Spectroscop Europe, 2005,17(5).
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CONTROLLING THE SPREAD OF INFECTIONS IN HOSPITAL WARDS BY THE USE OF ANTIMICROBLALS ON MEDICAL TEXTILES AND SURFACES W. Curtis White’, Roger Bellfield2,Dr. John Ellis3, and Ir. Patrice Vandendaele4 EGIS EnvironmentalManagement, Midland, MI USA Carrington Career and Workwear Ltd, Adlington, PR7 4HJ,UK Devan-PPT Chemicals Ltd, Dylan Laboratories, Ambergate DE56 2EY, UK 4 Devan Chemicals NV, Ninoofsesteenweg539,9600 Ronse-RenaiX, Belgium ABSTRACT The hospital and healthcare system is challenged by the presence of microorganisms and the negative effects they cause. Deterioration, defacement and odors are all dramatic effects which occur from the microbial contamination of surfaces as vaned as uniforms and medical nonwoven fabrics to medical devices and hard surfaces i.e., walls, ceilings, and air duct systems. Most significantly, these surfaces can act as microbial “harbors and transfer site (vectors),” offering ideal environments for the proliferation and spread of microorganisms that are harrnhl to buildings, textiles, and humans. The ability to make microbial resistant surfaces in a healthcare environment has advantages in many applications. This is especially true in healthcare and hospital environments where the emergence of hospital acquired infections caused by M R S A , Aspergillus sp., Clostridium drfficile, kfvcobacteriw spp. p), and other drug resistant species have threatened the health of its patients, staff, and visitors. According to a February 2007 National Statistics (UK) report, “The rates for deaths involving MRSA doubled for both male and females between 2001 and 2005.”’ In spite of the many precautions taken to prevent or reduce the transmission of harmful organisms in hospitals, such as handcleaning, housekeeping, and laundry protocols, the risk of cross contamination of surfaces and textiles to patients and staff is considerable Any textile material and hard surface in a hospital environment is a potential carrier of infectious agents such as bacteria, fungi, and yeast. The only effective strategy for reducing such infections and the conditions for reservoirs of organisms where resistance is stimulated is to reduce the dose of microorganisms throughout the healthcare complex using safe persistent antimicrobial technologiesto treat such surfaces and to maintain the highest standards of hygiene and use protocols for antibiotics. This paper outlines how a bound organofunctionalsilane antimicrobial has been and can be successfully used to reduce microbial dose on multiple s h t e s in a healthcare setting, i.e., medical nonwovens, blankets and linens, wound care materials, uniforms, and the hard surfaces that enclose and protect the healthcare environment. Labontory and field test data are discussed.
INTRODUCTION Textiles (wovens, nonwovens, and composite fabrics), soft goods, equipment, and indoor hard surfaces used in a healthcare environment have unique microbial problems and their control is a complex chemical, physical, and microbiologicaltask. Data generated h m t h e
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Shriners Hospital for Children and the University of Cincinnati College of Medicine indicate that “many of the h g i (Candida, Aspergillus, Mucor, and Fusarium) which are associated with nosocomial infections in patients survived for at least a day and often longer on fabrics and plastics routinely used in hospitals.”For example, housekeeping practices such as laundering of uniforms can help to arrest the spread of hannful agents, but contaminationthat happens through the working day cannot be controlled in this way and there is a growing trend for hospitals to close their own inhouse laundry services and to allow nurses to launder their uniforms at home. One may ask, “What do they take home?’ Using a holistic approach, by treating multiple textiles, hard surfaces, and devices with an antimicrobial finish, cross-contamination during use and abuse can diminish considerably. However, the antimicrobial agent must not i n t d u c e more problems than it prevents, such as microbial adaptation to the leaching microbial poisons employed with conventional antimicrobial chemicals. Furthermore, the treatment must be effectively permanent and should not cause problems such as irritation for the wearer. In order to understand microorganisms and their impact on medical materials, we must understand the uses and abuses of these materials. Just as the enduse is different for each article, the potential for microbial contamination and the ability to control this contamination are very different. Specific fabrics are darigned for different end-uses. Specific antimicrobial agents are added for different enduse performances, needs and claims. Specific antimicrobial test methods with specific parameters are used to measure these activities. The variability of the mtirnicrobial agents, test methods, end-uses and performance claims are enormous and require a set of standards and guidelines that W l all possible applications. Testing and evaluating these performances under accelerated laboratory conditions with respect to the real-world effectiveness are often the most challenging of endeavors. This type of accelerated scientific testing is done for basic research, evaluating and optimizing application processes, quality control, and marketing. The tests required and the interpretationsmade vary as widely as the questions posed. The evaluation of any antimicrobial test result requires a thoughtful and basic understanding of microbiology, understanding the strengths and limitations of each test, and understanding the mode of action of the antimicrobial agent in question. In turn,running clinical disease outcome related studies is almost impossible. The number of uncontrollable variables introduced fiom the outdoor and indoor environments, the patients, the staff, the visitors, the microbes in question and associated microbes, the operating systems of the facility, the building materials, the furnishings, the many soft goods, the genetics and health of the people in the study area, and the personal and prokssional habits and practices of the people involved. As daunting and expensive this is, case controlled studies are possible and do add to the understanding of the utility of antimicrobial interventions on goods and facilities. Results fkom any such case controlled or multi-variable designed field tests do not change or alter the common sense approach of reducing dose of microorganisms from the healthcare environmentas a first line of defense. MICROORGANISMS
Mold, mildew, fungus, yeast, bacteria, and virus (microorganisms), are part of our everyday lives. There are both good and bad types of microorganisms. The thousands of species of
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microorganisms that exist are found everywhere in the environment, on our garments and on our bodies. Microorganisms, their body parts, metabolic products, and reproductive parts, cause multiple problems to building materials and furnishings. They are human imtants, sensitizers, toxic -response agents, causers of disease, and simple discomforting agents. Clearly, microorganisms are the most potent pollutants in the indoor environment, on our clothes, and on our fiunishings. The human symptoms of building sourced microbial exposure involve an array of physical and systemic reactions affecting the skin, mucous membranes, eyes, yper and lower respiratory tracts and muscles. Some reactions are shorkterm (acute) and others are long-term (chronic). All affect productivity, health costs, and well-being. Similarly, microbes sourced from textile reservoirs can cause these same effects Healthcare facilities, schools, hotels, residences, food storage areas, and manufacturing facilities such as electronics, food, pharmaceuticals, and other asrisk material production areas need to have a reaction plan for avoidance and control of airbone and surface sourced microbial contaminants. Strategies for control of microbes must exist for garments, beddings, linens, wipes, surgical fabrics, and other textiles used in healthcare operations and construction materials. Microorganisms need moisture, nutrients, proper temperature, and most of them need to be associated with a surface. Moisture can come h m catastrophic and normal events- a leaky roof, a sweaty pipe, a leaky radiator, condensation on windows, condensation on more subtle surfaces where dew points are reached, humidified air h r n the W A C system the human body, or any of hundreds other sources. Air conditioners, bathrooms, wall-towall carpets, draperies, wall coverings, furniture,bedding and ceiling tiles create ideal habitats for microorganisms. These types of surfaces are found in buildings including offices, hospitals, schools, and homes. Nutrients utilized by microorganisms can be organic material, inorganic material, andor living tissue. For example, bacteria play an important role as part of the body’s microflora, and along with the skin, are shed continuously. Given acceptable growth conditions, they can multiply from one organism to more than one billion in just 18 hours.
ANTIMICROBLALS The term antimicrobial refers to a broad range of technologies that provide varying degrees of protection for products and buildings against microorganisms. These preservative antimicrobialsare very different in their chemical nature, mode of action, impact on people and the environment, in-plant-handling characteristics, durability on various substrates, costs, regulatory compliance and how they interact with good and bad microorganisms. Antimicrobials are used on textiles and other surfaces to control bacteria, fungi, mold, mildew, and algae. This control reduces or eliminates the problems of deterioration, staining, odors, and health concerns that they cause. In the broad array of microorganisms there are both good and bad types. Antimicrobial strategies for reducing the dose of bad organisms must include ensuring that non-target organisms are not affected or that adaptation of microorganisms is not encouraged. Antimicrobials that are fungicidal, when properly applied, limit greatly the life habits and environments for the common dust mite.
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Microorganisms cause problems with textile raw materials and processing chemicals, wet processes in the mills, roll or bulk goods in storage, finished goods in storage and transport, and goods as they are used by the consumer. These effects are extemely critical to clean room operators, healthcare facilities, and food processing facilities. They are also an annoyance and aesthetic problem to athletes and consumers. The economic impact of microbial contamination is significant and, in light of emerging pathogens, consumer demand for protection is at an all time high.
ORGANOFUNCTIONAL SILANE ANTIMICROBIAL TECHNOLOGY The bound unconventional antimicrobial technology, an organofunctional silane, has a mode of action that relies on the technology remahing affixed to the substrate - killing microorganisms as they contact the surface to which it is applied. Effective levels of this technology do not leach or diminish over time. When applied, the technology actually polymerizes with the substrate making the surface antimicrobiaL Durability to wear and launderingwith broad-spectrum antimicrobialactivity have been demonstrated. The unconventionalbound antimicrobial stays affixed to the textile and, on a molecular scale, physically stabs (the lipoprotein components of the membrane) and electrocutes (the anionic biochemicals in the membrane) the microorganism on contact to kill it. Like an arrow shot r fom a bow or bullet shot from a gun, leaching antimicrobials are often effective, but are used up in t k process of working, wasted in mdom misses, or complexed by other chemicals in the environments of use and abuse. Some companies incorporate leaching technologies into fibers and slow the release rate to extend the useful life of the antimicrobial, even adding to them chemical binders and claiming they are now “bound.” Whether leaching antimicrobialsare extruded into the fiber, placed in a binder, or simply added as a finish to fabrics or finished goods, they all function the same. In all cases, leaching antimicrobial technologies provide a killing field or “zone of inhibition.” This zone exists in real-world uses if it is assumed that the right conditions are present for leaching of a lethal dose at the time that it is needed. The zone of inhibitionis the area around the treated substrate into which the antimicrobial chemistry leaches or moves to, killing or inhibiting microorganisms. This killing or inhibiting action of a leaching antimicrobial is witnessed when an AATCC 147 test or other zone of inhibition tests are run. These tests are used to measure the zone of inhibition created by a leaching antimicrobial and clearly define the area where the antimicrobial had come off the substrate and killed the microorganisms in the agar. As fabrics treated with unconventionalleaching antimicrobial are washed, treatments are easily removed. Figure 1 presents graphically a typical zone of inhibition test method. The blue area represents a textile material treated with a leaching antimicrobial.
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1
‘The Zone of Inhibition Story
Fig. 1. Zone of inhibition.
Fig. 2. Wash durability. The clear zone surrounding the substrate represents the zone of inhibition and the sublethal zone is shown in gray. The area at which the zones merge is presented as the m e of adaptation. Figure 2 shows actual results on the difference between the leaching and the non-leaching antimicrobial treatments on textiles both as first treated and then after five household launderings. Microbes are living organism and like any living organism will take extreme measures to survive. Microorganismscan be genetically mutated or enzymatically induced into tougher “super-strains” if they are exposed to sublethal doses (exposed to - but not killed) of an antimicrobial agent This ability of microorganism to adapt to potential toxicants has been recognized in the healthcare community for years. Sublethal levels of antibiotics are generated in patients who discontinue taking antibiotics once their symptoms subside instead of continuing through to the end of the period prescribed by the physician. The exposure of the microbe to a sublethal dose of an antimicrobial can cause mutation of their genetic materials allowing for resistance that is then replicated through the reproductive process creating generations of microorganisms that are no longer affected by the chemistry. This phenomena is of serious concernto the healthcare community and food
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Figs. 3a, 3b, and 3c. The Microbial Adaptation Story. processing industries and should be a serious consideration for the textile industry as it chooses the antimicrobialsto which it will be exposingthe public and their workers. As with any chemistry that migrates from the surface - a leaching antimicrobial is strongest in the reservoir, or at the source, and weakest the farther it travels from the reservoir. The outermost edge of the zone of inhibition is where the sublethal dose can be found-this is known as the zone of adaptation (Fig. 1). This is where resistant microbes that have been produced by leaching antimicrobials are found. The ongoing challenge for leaching technologies is the control of the leach rate from their reservoir such that a lethal dose is available at the time that it is needed. This is demonstrated in the above images fiom experiments where a microbe sample was taken from the outer edge of the zone of inhibition of a common leaching antimicrobial. As with any chemistry that migrates fiom the surface - a leaching antimicrobialis strongest in the reservoir, or at the source, and weakest the farther it travels from the reservoir. The outermost edge of the zone of inhibition is where the sublethal dose can be found-this is known as the zone of adaptation (Fig. 1). This is where resistant microbes that have been produced by leaching antimicrobials are found. The ongoing challenge for leaching technologies is the control of the leach rate from their reservoir such that a lethal dose is available at the time that it is needed. In the experiment shown in Fig. 3, a sample was taken from treated carpet fiber (Fig. 3a) and used to inoculate a new test plate. This second test plate (Fig. 3b) shows the adapted microorganisms growing within the zone of inhibition. The adapted organism is taken from the second plate and used to inoculate a third plate (Fig. 3c). The microorganismused to inoculate this plate is fully adapted to the leaching antimicrobial and has overgrown the fabric. The ghost zone indicates the organism being slowed but not controlled by the leaching toxicant. All this occurred within just two generations of the test organism under these test conditions. A significantly different and much more unique antimicrobial technology used in the textile and building construction industries does not leach but instead remains permanently affixed to the surface on which it is applied? Applied in a single stage of the wet f d s h process, the attachment of this technology to surfaces involves two means. First and most important is a very rapid process, which coats the substrate (fabric, fiber, etc.) with the cationic species (physisorption) one molecule deep. This is an ion exchange process by which the cation of the silane quaternary ammonium compound replaces protons h m
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water or chemicals on the surface. The second mechanism is unique to materials such as silane quatemaryammonium compounds. In this case, the silanol allows for covalent bonding to receptive surfaces to occur (chemisorption). This bonding to the substrate is then made even more durable by the silanol functionality, which enables them to homopolymerize. After they have coated the surface in this manner, they become virtually irremovable, even on surfaces with which they cannot react covalently (Figs. 4a, 4b, and4c).
S y w Due
I
m, 1
8
LO*WtCwIIIIO)
-G C C G Q C G G 6 C C C CIo. ~''''Y1Pw. U (..
Fig. 4a Monomer
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Fig. 4b Polymer on surface
Fig. 4c Rupture mechanism Once polymerized, the treatment does not migrate or create a zone of inhibition so it does not set up conditions that allow for adapted organisms. Because this technology stays on the substrate, it does not cross the skin barrier, does not affect normal skin bacteria, nor
causes rashes or skin irritations. This organofunctional silane technology has beenused to treat surfaces from leather and foams to virtually all types of fabrics and is not consumed by the microorganism. It does not poison the microorganism. When a microbe contacts the organofunctional silane treated surface of the fabric, the cell is physically ruptured by a sword-like action and then electrocuted by a positively charged nitrogen molecule (Fig.5a and 5b). This antimicrobial technology has been verified by its use in consumer and medical goods including socks, surgical drapes, and capets in the US, Europe, Asia, and other areas of the world. This technology has been used for over thirty years without any human health or environmental problems inside manufacturing facilities or in actual end use situations.
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~
~~~
~~~
-
Figs. 5a and 5b. Cell lyses demonstrated.Escherichia coli, Staphlococcus aweus
VERIFICATION TECHNIQUES AND SAFETY PROFILE Another important property of a useful antimicrobial is that its presence should be verifiable. In effect, it is the only way to know that an antimicrobial is really on the product. There is no easy way to tell whether leaching antimicrobials are present on a product. The only known verification technique for a leaching chemistry is to use exacting laboratory tests, which take days or weeks to perform. With the bound antimicrobial technology though, a simple staining test can be performed in a matter of minutes at the mill or in a store to verify proper treatment of a fabric or other surface. This is a very important part of a quality assurance program that gives the manufacturer, the retailer, and the consumer confidence that a featue, normally invisible to the senses, can be seen and is actually on the product providing the protection for which they have paid. It is critical to review all uses of chemicals used in textiles in light of the intended use and the toxicological profile of the chemical. This is especially relevant as one remembers that antimicrobials, by definition and function, inhibit and/or kill living things. The mode of biological involvement needs to be fully understood so that a proper balance between risks and benefits can be made. For illustration, the following safety profile on the organofunctional silane AEM 5700/5772 Antimicrobial can be considered a minimum profile of needed data for qualifying antimicrobial treatments for use on textiles. The ability of the silanequat, when properly applied, to chemically bond to the textile substrate and still provide for the broad-spectrum control of microorganisms, makes it well suited to the safety challenges encountered in the full range of applications used in the healthcare industry. The following studies have been conducted with the silanequat: (a) acute oral, (b) acute ocular, (c) acute and subacute dermal, (d) acute vapor inhalation, (e) primary skin sensitization and irritation, (f) subacute vaginal irritation, (g) four-day static fish toxicity, (h) teratogenic evaluation, (i) subacute human wear test (socks), 0) human repeated insult patch test, (k) in-vitro Ames Microbial Assay with and without metabolic activation, (1) ie vitro mammalian cell transformation in the presence and absence of exogenous metabolic
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activation, (m) h v i t r o Host-Mediated Assay and (n) a percutaneous absorption study. Although certain handling cautions are indicated by data from the above tests, no untoward effects are notable regarding treated substrates. Further to these studies, Olderman reported on studies done by American Hospital Supply (Baxter Health Care), for a surgical drape that had been treated with the AEM 5700/5772treatment. These studies included the following prsclinical biocompatibility tests that are considered appropriate for skin contact medical products: (a) Tissue culture (cytotoxicity), to determine if a tissue culture medium (with serum) eluate of the test material can induce a cytopathic effect on monolayers of human (WI-38) cell, (b) Acute systemic toxicity to evaluate the potential of a single injection of an extract of the test material to produce a systemic toxicity response, (c) Intracutaneous irritation to evaluate the potential of a single injection of the test material extract to induce tissue irritation, (d) Eye initation to determine the response of the rabbit eye to the instillation of specific extracts of the test material, (e) Hemolysis to determine if a substance can be extracted ffom the material which is capable of inducing hemolysis of human red blood cells, (0 Human Repeated Patch Test to detennhe if the test material is capable of inducing skin irritation and sensitization under controlled patch test conditions and (g). Extensive leachability studies to evaluate the durability and nodeaching potential of the chemically modified fabric when exposed to copious amounts of physiological saline, water and simulated human sweat. The final results of these biocompatibility studies from the Oldaman report indicated that the AEM 5700/5772Antimicrobial treated fabric is nomtoxic, non-imtating and nonsensitizing to human skin, and has a permanent antimicrobial capacity that cannot be extracted in use. These prsclinical studies provide sufficient information to allow us to predict the biocompatibilityof the finished products and support their safe clinical use. As such, the treated fabric was considered safe for use in surgery. Years of clinical use with no untoward effects also support the suitability of the treated fabric for its intended use. POTENTIAL USES
With an understanding of microbial pests and antimicrobial technologies, we can begin to fit solutions to problems. Medical fabrics are used in a vast array of end-uses in the healthcare community and have an unlimited number of untapped uses available. These woven, nonwoven, and composite fabrics can be greatly enhanced by the use of the proper antimicrobialagents. Among the many challenges faced in choosing the right antimicrolid technology for the nonwovens, wovens, or composite fabric industry for healthcare applications include:
.
Durability: Durable fabrics need durable features. Endues of fabrics engineered for use in healthcare facilities must have antimicrobial treatments that can survive abrasion, sterilization, wet/dry cycles, freeze/thaw cycles, alcohol rinse, and other physical and chemical stresses. Waste Control/Toxicity: Antimicrobials control a range of microbial pests but in their use must be chosen and engimered so that they do not affect good and helpful microbes. Although heavy metals have long been rejected where they come into
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.
.
contact with the environment or human skin contact, silver-based products have unexpectedly made a resurgence. Spectrum of Activity: Many materials are antimicrobial at the right concentration but in healthcare applications it is very important to have as broad of spectrum of activity as is safe and functional. When integrating antimicrobial treatments into durable goods, this is even more important. A broad spectrum antimicrobial will have activity at the deliverable concentration or contact concentration that kills or inhibits Gram (+) bacteria, Gram (-) bacteria, yeast, and mycelial fungi. Added spectra could include algae, virus, or other microbial pests. Ever more, specialized chemistries have activity against tuberculosis, other pathogenic organisms, or microbial spores. Adaptation: Any soluble agent that affects a microorganism’s life has the potential to set up conditions where the microbial cells adapt or mutate into resistant types. This is bad in almost all settings but clearly should not be tolerated in a healthcare facility. Use of standard disinfectants or sanitizers call for a rinse after the desired contact time. This is to minimize the risks associated with sublethal levels of the antimicrobial being present and risking adaptation or other forms of resistance.
Engineering the right antimicrobial usage requires a thorough understanding of the e n & w and subsequent use and abuse of the finished goods. In the healthcare industry, industrial fabrics have proven and potential utility in a wide array of end uses. With the inhstructure in place to design and produce the variety of fabric materials used in industial fabrics, the industry has the tools and products to fit many needs in the healthcare marketplace. 0
. .
.
Construction Materials: Roofing and envelope materials integrated with the engineered textiles can offer installation and performance properties that mike them a preferred choice over any alternatives. Antimicrobial treatments enhance the value of these products. Finishing Materials: Engineered textiles have a tremendous potential as components of ceiling, wall, and flooring structures. Their use as awnings, tarps, and tents are well integrated into healthcare facilities as functional and decorative materials. These aesthetic and functional materials all benefit from antimicrobial treatments. Furnishing Materials: As components of upholstered furniture, bedding, or carpeting, engineered fabrics have a unique role to play and strengthen their value with antimicrobial treatments. Housekeeping Goods: From wipes, mops, sponges to other cleaning supplies, engineered fabrics have utility and with an anlimicrobial finish, serve a more durable and functional life.
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Garments: Engineered textiles bring strength, cleanability, bmthability, insulation properties, barrier properties and antimicrobial treatments as valuable assets to many uses. These properties are all important in the great variety of garments used in healthcare care operations. Central Storeroom Materials: Bedcovers, linens, wraps, drapes, covers, and other textile or film-like materials can all be made and made better with engineered fabrics. The mix and value of properties of nonwoven, woven, and composite fabrics are a certain opportunity for engineered fabrics with antimicrobial treatments. The SiQuat technology is used on a variety of woven and nonwoven textiles used in healthcare facilities. Fenestrations of surgical drapes, mayo stand covers, uniforms, sponges, and h e n s are among the products that take advantage of the safety profile and antimicrobialeffectiveness of this technology. These treatments not only provide protection h m microorganisms they also add aesthetic and emotive values to a 111 range of products. Deterioration, defacement, odors, and "harboring" medically significant microorganisms are all dramatic effects we see in buildings and products where microbial contamination is present. The ability to make surfaces and nonwovens, wovens, and composite fabrics resistant to microbial contaminationhas advantages and values in many applications and market segments served by the industrial fabrics industry. Some examples of successll use of this technology under the predictable abuse and clinical settings found in the healthcareindustry include the following.
HOSPITAL BLANKETS EGIS Environmental Management participated with Spartan Mills and the Virkler Company in studying blankets that we= treated with the EGIS Microbe Shield (AEM 5700) technology and blankets that were untreated. In any environment, blankets can become a haven for bacteria. These bacteria usually represent a spectrum of Gram positive and Gram negative organisms capable of producing infections, Staining, deterioration and odors. In a hospital environment, fever and sweat are common and an excellent source of bacterial contamination. In an effort to evaluate the effects a hospital environment has on treated and untreated blankets two separate studies were undertaken. The first simulation study was initiated to simulate the types of exposures blank- receive when in use on a feverish patient. The second imuse study was initiated to determine the effectiveness of the antimicrobialon blankets when stored and used within a care facility. The in-use study on Spartan Mills blankets correlates well with the simulated study undertaken earlier in the year. Both studies clearly show that blankets treatd with the &GIs Microbe Shield technology have a significantly lower bioburden and will present less of a risk in the patient environment. Historical data generated by American Hospital Supply and Dow Coming Corporation supportsthese findings. These data generated by university, medical and industrial laboratories represent some of the most extensive microbiological work ever performed on antimicrobial treated
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substrates for use in the healthcare community. The control of the microorganisms is impressive and provides numerous benefits. Prevents blanket staining due to mold and mildew growth that occurs on damp blankets prior to laundering. Controls blanket deterioration due to microbial growth that occurs on blankets during storage. Controls odors caused by bacteria and fungusnormally found in blankets. Provides 3 times more protection from bacteria and fungus than an untreated blanket.
NONWOVEN SURGICAL DRAPES A considerable body of microbiological efficacy data was generated to support the effectivexss of the nonwoven surgical drape through a variety of microbiological toola. These included: in-vitro tests, Scanning Electron Microscopy (SEW work (Figs 5a and 5b), and clinical evaluations. The purpose of these tests was to support claims relating to the reduction of microbial dose on the drape in the vicinity of the wound. The surgical drape fabric was found to kill the bacteria commonly associated with surgical wound infections and takes an active role in maintaining an aseptic field at the wound sfe. The antimicrobial surface serves to isolate the wound from bacterial transfer h m the drape surface. The antimicrobial component of this fabric was chemically bonded, safe for use in surgery, and did not lose its effectiveness when sterilized, stored, or handled during the manufacturing procedure or in surgery. Representative data are presented in Tables 4 11, and 111. Table 1 shows results of laboratory testing on SiQuat treated nonwoven (Kaycel: Kimberly-Clark) fabrics against a broad spectrum of bacteria and yeast using a padding contact test protocol (AATCC 100). Table 2 shows results against a battery of clinical isolates on SiQuat treated Son$ra,@ Dupont. Table 3 shows results comparing untreated linen, untreated Sontara, and SiQuat treated Sontara with a 15 minute contact time of the bacterial insult in the presence of various buffer and irrigation fluids. Under all of these stress conditions against the variety of test organisms, the SiQuat showed h m one to three log reductions of the test organisms.
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Table 1. Laboratory testing on SiQuat treated nonwoven (Kaycel? Kimberly-Clark) fabrics against a broad spectrum of bacteria and yeast using a padding contact test ptotocol (AATCC- 100).
AATCC Metbod 100, AntimicrobirLs on Fabrics' AEM 5700 Antimicrobial Agent Treated Nonwovens SamDle
Microorganism Reduction
Percent
Staphylococcus aureus Gram (+) Bacteria
Control Treated
16 100
Escherichia coli Gram (-)Bacteria
Control Treated
0 99.6
Klebsiellapneumoniae Gram (-)Bacteria
Control Treated
0
Saccharomyces cerevisiae Yeast
Control Treated
0
100
99.9
' W o n t FC-170 surfactant used, substituted for Rohm and Haas Triton X-100 Fabric was Kavcel
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Table 2. Clinical isolates on SiQuat treated Sontar&* hpont.
Cliaical Isolate controP
AEM 5700 Antimicrobial Agent Treated Nonwovens sunuk!
Mlcroolnanisms Reduction
Percent
Citrobacter diversus Wound Isolate
Untreated' Treated Inoculum
14.3 93.6 0
Pseudomanas serugimsa Urine Isolate
Untreated TEated Inoculum
28.3 99.9 0
Staphylococcusaureus Wound Isolate
Untreated Treated hoculum
0 99.7 0
Escherichia coli Urine Isolate
Untreated Treated Inoculum
11.6 98.6 0
Proteus mirabilis Wound Isolate
Untreated Treated Inoculum
0 99.5 0
' Sontara Fabric
'
ASTM E-2149-01
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Table 3. Comparison of untreated linen, untreated Sontara, andSiQuat treated Sontara with a 15 minute contact time of the bacterial insult in the presence of various buffer and irrigation fluids.
I
Fluid Compatibility TeeQ
AEM 5700 AntimicrobialAgent Treated ISaBAC Fabric Percent Reduction' with 15 min. Contact
I
Sample
Buffered Phosohate
saline
Serum
Untreated Linen
8
0
0
Untreated Sontara Nonwoven
0
0
0
Treated Sontara
99+
904-
90+
'
Modified AATCC method 100 using test fluids Klebsiella pneumonia statistically significant at the 95% confidence level.
WOUND CARE SILK DRESSINGS The Department of Pediatrics at the University of Bologna evaluated the effectiveness of a special silk fabric (MICROAIR DermaSilk treated with AEM 5700) in the treatment of young children affected by Atopic Dermatitis (AD) with acute lesions at the time of examination7. Using the SCORAD index, a significant decrease in AD severity was noted with the treated dressings (mean SCORAD decrease from 43 to 30: P= 0,003). This allowed for the conclusion that such treated clothes (dressings) should be useful in the management of AD in children.
CARPETING An aqueous solution of the EGIS Antimicrobial SiQuat was applied to dry carpeting in accordance with the manufacturer's specifications8. Carpeting was not cleaned prior to antimicrobial applications. Building occupants in 6 of the buildings were not aware of any remediation activities. Although samples were performed during normal work hours, application of the treatment was performed at night or on weekends without their knowledge. The pre and post treatment retrieval averages are reported in Table IV. These averages are derived by dividing the total number of colonies retrieved by the number of plate sites. The variances between pretreatment and post-treatment retrieval averages range between 71 and 98%. Within this group of buildings, 2 (20%) showed greater than 90% change, 9 (90%) greater than 80% change, and 10 (100%) greater than 70% change.
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The actual retrieval counts at 33 sites within a test building are representative of pattern observed in the 10 buildings in this study. The pretreatment variances range from 2 CFUIplate to 156 CFU/plate whereas the post- treatment retrieval counts range only h m 0 CFU/plate to 4 CFU/plate. This stabilization of the aeromicrobiological retrievals is noteworthyalong with the consistently effective reduction in numbers retrieved. Table 4. PR and Post Fungal Retrievals Fmml Retrievals in 10 Buildin@ PKCandpaFt-AEGISAntimicrobial lhutment
hn.mm
1
2
3
4
5
6
7
8
9
Building10
13.4
28.0 1.7 719’0 29
54.0 8.0
403 1.0 95.5% 45
32.0 1.4
20.3
36.0
4.8 839’0 47
3.5 89% 14
26.0 4.1 85% 30
27.4 4.0 88%
17.0 3.3 83% 15
ma,CNlRa V
W
Nb. d b s
87% 50
98% 33
85% 20
20
2.9
UNIFORMS A clinical study is currently being conducted comparing nurses’ uniforms treated with EGIS Microbeshield (Permagad@,Carringtons), with untreated uniforms. The uniforms will be worn during normal hospital duties for a period of 36 days. The microbial count h m the inner and outer faces of the fabric was determined by removing microbes h m each surface by physical means (elution) and the isolated organisms were then transferred to a culture medium for counting to estimate the control of contamination on the textile surface. The study should show that the application of a cost-effective, permanent antimicrobial treatment to uniforms is a significant contributor to the reduction of bacterial flora on the garments and to the prevention of the spread of nosocomial infections in hospital wards. The details of this study will be released in the next coming months.
SILICONE RUBBER IMPLANTS Various medical devices that are insertedinto the bodies of humans can introduce bacterial, viral and fungal infections into these body cavities?. Silicone, as used in biomedical implants and devices, are susceptible to these feared complications of contamination, potentially causing serious infections to the patients it serves. A study published in the March 2002 issue of Biomatenals silicone rubber was studied for the antimicrobial efficacy of the 3(trimethoxysilyl)propyldimethyloctadeylammoniumchloride (QAS) on both treated and untreated samples. Gram-positive Staphylococcus aureus, Staphylococcus epidermidis, and Gram-negative Escherichia coli and Pseudomonas aeruginosa were seeded onto both the QAS untreated and treated samples for In Vitro and In VIvo evaluation. The study concluded, “Preoperative seeding resulted in infection of 7 out of 8 silicone rubber implants against 1 out of 8 QAScoated silicone rubber implants. Postoperative
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seeding resulted in similar infection incidences on both implant tpes, but the numbers of adhering bacteria were 70% lower on QAScoated silicone rubber.
CASE STUDY THE ARTHUR G. JAMES CANCER CENTER HOSPITAL AND RESEARCH I N S ” E The study building is a 12-story comprehensive cancer center and research institute located in Columbus, Ohio”. Just prior to its opening in January, 1990, a ruptured water pipe on the 12* floor flooded the building with an estimated 500,000 gallons of water. Ceilings, walls, carpeted floors and upholstered firmishings were either wet or exposed to high humidity. After assuring that the building’s structural integrity had not been compromised, attention focused on restoring the microbiological quality of the building to levels consistent with its intended use, particularly in Bone Marrow Transplant area and other areas where immunosuppressed patients would be housed. Despite high efficiency air filtration, and widespread use of a chlorinebased disinfectant fog throughout the building and its ventilation system, large numbers of fungi and bacteria were retrieved from the air in all areas of the hospital. Large numbers of watemssociated bacteria, such asAcinetobacter sp., as well as funsi were retrieved from carpeting. Prior to the flood, hospital and university researchers had designed a study protocol to investigate the effect of surface modification with silane antimicrabialson infection rates within the Bone Marrow Transplant, Hematology and Oncology areas in the hospital. The flood and subsequent microbial contamination preempted the study. But, investigation of various antimicrobial systems to achieve sustained microbial control during the study provided an important tool for use in remediation and beyond. All accessible interior surfaces (including carpeting, ceilings, walls, above ceiling space, fiynishings, elevator shafts, mechanical and electrical chases) were treated with the organosilicon antimicrobial 3-trimethoxysilylpropyldimethyloctadecylammonium chloride (EGISm Antimicrobial) in water in accordance with the manufacturer’s application specifications. The applications were randomly tested for uniformity and penetration throughout the treatment process. The results were:
0
0
Pre-treatment retrievals were in a range of 721 - 2,800 CFU’s/m3. Of the 209 sample sites, 122 (58%) sites produced 2,800 CFUWm3,the upper detection limit of the sampler. Post-treatment sampling during the seven months following restoration of the building produced an average of 4.1 CFU’s/m3 at 643 sites. Retrievals were in a range of 0-25 CFU’s/m3. Of the sample sites, 289 sites (45%) produced 0 CFU’s/m3; an additional 231 sites (36%) produced retrievals in a range of 1-5 CFU’dm3. The second post-treatment samplings were performed in 1991 at 82 sites randomly selected by floor. The samplings produced retrievals in a range of 0 9 CFU’s/m3, with an average retrieval of 0.8 CFU’s/m3. 40 sites (4Ph) produced 0 CFU’s.
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0
0
The final post-treatment samplings were performed in 1992 at 86 sites randoml Y selected by floor. The samplings produced retrievals in a range of 04.7 CFU’s/m , with an average retrieval of 0.4 CFU’s/m3. 56 sites (65%) produced 0 CFU’s. Each of the 24 Bone Marrow Transplant patient rooms was negative for microorganismsduring all of the post-treatment samplings.
The facility is presently free of odor and has a new appearance unaffected by the extensive application of a surface antimicrobial. No fungal nosocomial infections were reamid in this facility during the 3Grnonth study and a post study check after five years. All renovations or reconstruction in the facility were strictly controlled and all newly added or modified surfaces were treated with EGIS Antimicrobial for five yea^^ after the initial treatment.
SUMMARY The health care industry is challenged with providing the best possible care for their patients and a safe environment for health care. workers. Microorganisms are the most prevalent and potent pollutants in the indoor environment and their role as causers and aggravators of disease conditions are well documented. Reducing dose of microorganisms in the healthcare environment by eliminating reservoirs and transfer surfaces using safe and effective antimicrobial treatmnts is critical to lowering nosocomial infection rates and has been clearly demonstrated with the use of the SiQuat &GIs Technology on a wide range of substrates and clinical settings. Control of environmentally sourced microorganisms in a building and m building materials is best accomplished by using design and technologies from the beginning of a building’s life to its demolition. This includes all of the textile materials used throughout the life of the facility. No place is this more important than in health care facilities. Intervention at the time of construction with an organofunctional silane antimicrobial has been shown effective at reducing exposure and risks associated with microorganismsin bone marrow transplant units,operating theaters, ICUs, recovery moms, office areas, and general service areas of healthcare care facilities. Treatment of fabrics used in all areas have shown the benefits of reducing microorganisms. Reduced odors, staining, and deterioration as well as the real opportunity to enhance product value by reducing reservoirs and amplification sites for problem causing microorganisms improves products and steps towards asepsis. To benefit from the demands for antimicrobial/antibterial products as well as the antimicrobidantibacterial performance needs of the medical products world, manufacturers have a choice. In choosing,they should utilize a treatment that provides for a microbial control claim and an antimicrobial finish for their textile products consistent with the needs of their target consumers. This selection should be done by considering the following:
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1. Adopting a non-leaching antimicrobial that doesn’t pose the risk of crossing the
skin barrier or negatively affecting the normal microbial flora of the skin If it creates a “zone of inhibition” or must integrate into the all to have function, it leaches or moves and has the potential to cause problems to people and the environment. 2. Adopting an antimicrobial technology with a proven history of use. This will help shorten the timelines in bringing products with an antibacteriaYantifungaYodoF reducing, antimicrobialfeature to market. 3. Adopting an antimicrobial technology that is adaptable across many utilities and stand up to use and abuse conditionsthrough the life of the good. 4. Adopting a non-leaching antimicrobial that doesn’t pose the risk of creating
adaptative resistant microorganisms. 5. Adopting an antimicrobial technology that is registered with the EPA, the EU, BPD
and other regulatory agencies for the specific product it is applied to. 6. Adopting an antimicrobialtechnology that can be tested for proper application at the mill or at the retailers. A verifiable quality assurance program should be a key component of any applicationprocess. 7. Adopting an antimicrobialtechnology that has technical and marketing support.
REFJERENCES 1 National StatisticsReport. Deaths Involving MRSIA and ClosiridiumdifficileContinue to Rise. News Release. National Statistics. United Kingdon. February 22, 2007.
h~:Nwww.statistics.aov.uk/hub/search/i 2 A N Neely and M M Orloff, ‘Survival of some medically important fungi on hospital fabrics and plastics,Jof Clinical Microbiology, 2001 3360-3361. 3 J R Malek and J L Speier, ‘Development of an organosiliconeantimicrobial agent for the treatment of surfaces’, J of Coated Fabrics, l2 38- 46. 4 W C White, and J M Olderman, Antimicrobial Techniquesfor Medical Nomvovem: A Case Sit&. Proc. INDA. 1982.
5 J W Krueger, Reducing Microbial Contamination in Hospital Blankets, 2003.
6 W C White and J M Olderman, Antimicrobial Techniquesfor Medical Nonwovens: A C’e Study. Proc. INDA. 1982.
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7 G Ricci, A Patrizi, B Bendandi, G Menna, E Varotti, and M Masi, ‘Clinical effectiveness of a silk fabric in the treatment of atopic dermatitis’, J of fiimatology, 2004 150 127-131. 8 R A Kemper, W C White and R L Gettings, Sustained Aeromicrobiological Redirctions Utilizing Silane-Modijied Quaternary Amines Applied to Carpeting: Preliminary Data From an Observational Study of Commercial Buildings. Dev. Ind. Microbial. 31 237-244. (J I d . Microbial., Suppl. No. 5), 1990. 9 Gottenbos, Bart, van der Mei, Henny, Klatter, Flip, nieuwenhuis, Paul and Henk J. Busscher. ‘In vitro and In vivo Antimicrobial Activity of Covalently Coupled Quaternary Ammonium Silane Coatings on Silicone Rubber‘, BioMaterials, March 2002 1417-23.
10 L Ayers, B. Fox, C. Jacobson, C. Smith, R. Kemper, and C. White. Ohio State University Case Study - Aeromicrobial Control in an Extensively Damaged Hospital Using a Long Lasting, SMace Active, Silane Antimicrobial. 18th Annu. Educ. & Intl. Cod. of Assoc. Practitioners in Infixtion Control. May 7 1991.
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INHERENTLY ANTIMICROBIAL ALCHITE FIBRES DEVELOPED FOR WOUND CARE APPLICATIONS M Miraftab, C Iwu ,C Okoro and G Smart University of Bolton, Institute for Materials Research and Innovation,Deane Road, Bolton BL3 S A B , UK ABSTRACT
Alginate fibres are well established as primary wound dressings given their well-known sodium/calcium ion exchange ability at the wound surface coupled with their good liquid absorption characteristics. Chitosan, the deacetylated form of chitin is also well-known for its haemostatic, antimicrobial and wound healing ability. This paper discusses on unique combination of these two polysaccharides leading to the development of atruly conjugate fibre (Alchite) with distinctive physical and mechanical properties different to those of alginate and chitosan fibres. The report discusses the developmental steps leading to t.k production of this unique fibre and examinestensile, liquid absorbency, morphology and IR charactensation of the new fibre. It further examines its antimicrobial properties in company of Staphylococcus Aurous and Epidermis, two common skin and wound bacteria
INTRODUCTION With an annual average of 40 new dressings passing through the Drug Tariff in the last 10 years, the market for advanced wound dressings is changing rapidly. Utilization of sophisticated biomaterials and biotechnology in the makeup of modem wound dressings offer a range of multi-functionalabilities and claim better and more effective treatmentj of wounds. Alginate and chitosan, two polysaccharide-based materials are well-known in the wound care arena and commercial alginate dressings undervarious brand names appear in most hospitals and clinics around the world'"). Sodium/calcium ion exchange between alginate dressings and exudate is recognized as the key mechanism responsible for gelformation and hence the high liquid absorbencyof this fibre which also allows trauma f k e removal. The moist environment also contributes to the wound repair or reepithelialiition. Chitosan, the deacetylated form of chitin is naturally antimicrobial, haemostatic, biocompatible and is widely believed to have good healing properties due to its vulnerabilityto break down by tbe enzymes present in the exudate and their subsequent role in regeneration and prolifmtion of new Chitosan,unlike many other materials is highly reactive due to its amino and hydroxyl groups carrying a positive charge at pHs below 6.5. Most natural materials including fibres, human skin, bone, hair and microbes bear negative charges and are therefore potentially capable of interacting with chitosan. One such possible interaction is the combination of alginate and chitosan in a single fibre with the view of achieving combined properties However, straight solution mixing forms a gel and the elled blend cannot be extruded using normal wet spinning machines. Some researchers (4*7) have explored physical blending of these fibres and have reported some benefits but more interestingly others have tried coating calcium alginate fibres with unhydrolysed and h y d d y ~ e d ~chitosan * * ~ ) to achieve bi-functional effects. Miraftab et
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al('O) describe in detail how hydrolysed chitosan could be coated on an alginatebased fibre so as to achieve coresheath effect as a bicomponent fibre. Although this is highly feasible,
the coating can be inconsistent and could potentially lead to poor distribution of the chitosan over the core material along the fibre length. This paper reports on a new technique of combining these two polysaccharides at the point of inception where instantaneousinteraction prevents uneven distribution of either component along the entire fibre length leading to some unique fibre properties.
PRODUCTIONMETHODOLOGY Materials and machinery wed: Protanal LF 10/60 alginate was supplied by F.M.C. Biopolymer, Norway and Chitosan with degree of deacetylation greater than 80% was obtained h m Kate International, India. Calcium Chloride dihydrtate, CaC12.2H20, 98%, h m Sigma Aldrich, and Acetone Propanone, CH3COCH3, 99%, were supplied by Sigma Aldrich and VWR International UK respectively. Likewise Hydrochloric acid (HCl, 36% w/w) and Glacial Acetic acid (CHFOOH, 100%) were supplied by Hopkin & Williams and BDH Laboratories. Brookfield Syncrolectric Viscometer and standard pH meters were used to measure viscosity and pH values respectively. Standard SEM and FTIR were used for imaging and analysis purposes. 600ml of chitosan solution based on chitosan content of 3.84%w/v, 1% acetic acid and -3% hydrochloric acid was madeup and thoroughly stirred for over 5 hours before being heated under reflwc for 8.5 hours. This solution was then used as the coagulant for the spinning alginate dope. 5% wlv solution of the alginate was also prepared in preparation for extrusion and placed in the dope tank over night to degas. Under pressure, alginate dope was extruded directly into the prepared chitosan bath where upon direct contact between the two components, the alginatechitosan or Alchite fibres are generated. This was then fed through a second set of rollers and drawn. The dram fibres were subsequently washed and dried in acetone solutions. Full o erational details and extrusion parameters of the extruder machine is reported elsewhere 8 0 ).
RESULTS AND DISCUSSION Calcium alginate and alchite fib= were produced at different draw ratios and tested for fibre diameter, linear density and liquid absorption characteristics 8 given in Table 1. Table 1:Comparative physical properties of Alginate and Alchite fibre Fibre Alginnte
Draw
Coagulntioa
Fibre
-ti0
Bath
Diameter
1.15
(pm) 1.00?/0 CaC12 36.5
Alginate
1.23
AIginate
1.31
solution 1.00% CaClz 30.0 solution
5.6
1.00%
5.2
CaClz 30.0
solution
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6.5
Fibre Diameter swell ratio 1.6
9.7
7.1
1.4
4.3
6.1
1.6
Linear Water D e ~ l t y Retention (dtex) [g/g] 6.1 9.9
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Saline Retention Ig/gl
Alchitc
1.08
Alehite
1.15
Alehite
1.23
Hydrolyzed ChitOsm$Cl Hydrolyzed chitman,CI Hydrolyzed
37.2
14.0
22.5
12.1
3.6
58.6
13.4
35.0
12.0
2.3
50.41
18.7
16.3
11.5
2.0
In general, alchite fibres are coarser than alginate fibres despite similarity in extrusion parameters and their subsequent drawings. They are also heavier, displaying up to three times larger linear density than the alginate fibres. This large variation in diameter inevitably leads to greater ability to take up water and saline i.e. up to a maximum of 35g/g of water uptake when drawn at 1.15 draw ratio. The water pick-up and retention capability of the fibres are influenced by the fibre composition and less significantly by variation in draw ratios. The calcium alginate fibres showed reasonable water retention capacity as high as 9.9 times their original weight. The alginates retention of saline solution however, is much less. Saline being identical to serum found in wounds is a better indicator of absorbency in natural wound environment. The reduced retention or absorbency can be attributed to the presence of the salts in the saline solution. The fibres ability to absorb moisture has obviously been reduced by the salts present in the solution. The alchite fibres showed much increased water and saline solution retention capabilities. There was however, no linear relationship between absorbency and increasing draw ratio. The increased absorbency can be attributed to greater surface area i.e. larger diameter and the presence of the chitosan component Interestingly, the alchite fibres in wet state, appeared distinctly different to alginate fibres displaying good gelling tendency. While calcium alginates fibres can only swell to just under twice their original diameter, the alchite fibres swelled considerablymore. In fact they multiplied in diameter by as much as four and half times; with least absorbent multiplying to twice the original diameter. Table 2: Comparative tensile properties of alginate and alchite fibres Code
AIginate
Draw hti0 1.15
Coagulation Elongation Bath (Yo)
Tenadty
1 .OO% CaClz 2.9
4.7
WorktoRapturc (eN*cm) 0.1
5.4
0.2
6.1
10.5
0.5
5.3
3.3
0.3
15.5
6.0
2.0
12.4
4.7
2.1
(cN/tas)
solution Alginate
1.23
-ate
1.31
Alehite
1.08
Alchite
1.15
Alcblte
1.23
l.W/.CaCl~ 4.6
solution 1.00%CaCI2 solution Hydrolyzed chitosaqc1 Hydrolyzed Chitosm$Cl Hydrolyzed ChitoSaqCl
The calcium alginate fibres demonstrated an expected increase in tenacity wih increasing draw ratios. The tenacities increased h m 4.7 cN/tex (at 1.15 draw ratio) to 10.5 cN/tex (at 1.31 draw ratio), see Table 2. The tenacity of the alchite fibres also increased as draw ratio
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increased although a drop at 1.23 draw ratio was noted This is consistent with results reported by Tamm et a1 (*) who showed that chitosardginate based fibres have higher tenacities than calcium dginate fibres. However, the chitosanalginate fibres produced by Tamura were based on unhydrolysed chitosan and were coated rather than ceextruded as is the case with these fibres. When alginate and hydrolysed chitosan come into contact, strong ionic bonds, as shown in Figure 1, are thought to be responsible for their ultimate attractions which also play a part in improving fibre tenacity.
Figure 1:Possible ionic interaction between alginate and hydrolysed chitosan components(9) To ascertain further insight, infi.ared spectra (IR) measurements were carried out on a NICOLET Magna IR Spectrometer 550 for prre chitosan powder, calcium alginate fibres and the alchite fibres. 20Omg of powdered KBr was kept at about 60°C and mixed with 2mg of each of the calcium dginat6 chitosan and alchite fibres and grounded manually in a mortar. Prepared mixed powders were kept in an oven for about 3Omins before being pressed into pellets using KBr Perkin Elmer die kit at 15 tonnes for 15minutes. The respective spectra were generated after 32 scans between 4000 and 400cm'. These are shown in Figures 2-4.
I .
0.)
I
'*.
ub
; I I
. .% .
..,
wt
,",,
II
-Inn
I
*br
-
Figure 2: FT IR Spectrum of Chitosan powder.
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-
- 1
1j
-r-= IY
Figure 3: FT IR Spectrum of Calcium alginate fibres, AL'
Figure 4: FT IR Spectrum of Alchite fibre CHI
All samples showed peaks at 1070 cm-' which corresponds to C-0 stretching bands. The characteristic peak of alginates is seen in the calcium alginate fibre spectra at 1644 cm' correspondingto Carbonyl (C=O) bond or carbonyl stretching in amide I as well as amino group (1 173 cm"). The pure chitosan powder spectra s h o d characteristic bands of amide-I (1628 cm-I) and amino group (1 170 cm-I). In the alchite spectrum, the amide peak shifted to 1650 cm-I, while the 1173 cm-' amino peak was absent. The calcium alginate fibres showed peaks at 1520. This peak is either absent in alchite sample or shifts to 1528 cm-' in the alchite spectra. This is believed to indicate amide LI (GN) which usually occurs at about 1570 cm-'. The IR spectra of calcium alginate showed absorption bands at 3472 cm-' representing hydroxyl stretching. The chitosan powder showed a hydroxyl stretch at 3433 cm-'. The OH stretching of the alchite fibres shikd to 3444 cm-' which is prominent and relatively isolated as is in the calcium alginates and pure chitosan.However, three new peaks appeared in the alchite fibres' spectra which were conspicuously absent from either of the pure chitosan or calcium alginate spectra. The alchite fibres showed peaks at 1680
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cm-’, 1720 cm“ and a C-H stretching peak at 2878 cm-’. These peaks clearly require further investigations. Scanning electron and optical examination of alginate and alchite fibres in dry and wet state also highlighted interesting features. These are shown in Figures 5-10
Figure 5: Scanning electron micrograph of alginate micrograph of fibre
Figure 6: Scanning electron alchite fibre
Alchite fibre has rugged surface features as compared to rather smooth surface of alginate fibres.
Figures 7: Optical image of alginate fibre ‘‘dry”
Figure 8: Optical image of alginate fibre “wet”
Figure 9: Optical image of alchite fibre “dry” Figure 10: Optical image of alchite fibre “wet”
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The optical images 5-10 are taken at identical magnifications. Clearly alchite fibre diameter showed an enlargement more than twice that of alginak fibre when exposed to few droplets of water. This is particularly interesting as complete absorption occurs almost instantaneously. Alchite fibre has rugged; wool-like surface features, as opposed to rather smooth and plain surface characteristics of al@te fibres. The antibacterial properties of calcium alginate fibres and that of akhite fibre were examined against staphylococcus aurous and stqhylococcus epidermis, using the standard contact method. Both alginate and alchite fibres showed antimicrobial properties, alchite fibres in particular showed more effective k i h g of staphylococcus aurous than staphylococcus epidennis However, due to suspected secondary contamination these results were not entirely satisfactory and further verifications arenecessary.
CONCLUSION A novel method of producing a fibre based on two natural polysaccharides has been described. Alchite fibres can be successllly produced by extruding sodium alginate into hydrolyzed chitosan bath. This uni ue production method outperforms earlier methodologiesreported by Tamura et al and Miraftab (lo) et al and improves both fibre characteristics and production efficiencies. New FTIR peaks suggest formation of new bonds and molecular restructuring. Distinctive surface morphologies highlighted by both optical and scanning electmn microscopes are fiuther evidence of a new generic fibre with particularly high affinity for liquid absorption. Although, less conclusive, the antimicrobial properties of the chitosan component in the new fibre could prove to be most effective when used as wound dressing.
REFERENCES 1 Technical Textiles, ‘A special survey’, Textile Horizons, 23-25, (1995). 2 Y Qin, 0 C Agbor, X Wang and D K Gildin& ‘Novel polysaccharide fibres for advanced wound dressings’. In S.C. Anand(ed.) Medical Textiles 96, Woodhead publishing, Cambridge, 15-20, (1997). 3 L L Lloyd, J F Kennedy, P Methacanon, M Paterson and C J Knill, ‘Carbohydrate polymers as wound management aids’, Carbohydrate Polymers, 1998 37 3 15-322.
4 W Paul and C P Sharma, ‘Chitosan and alginate wound kssings: A Short Review’, Trendr Biomater. ArtiJ Organs’, 2004 18 18-23. 5 E Khor, CHITZN:Fulfilling a BiomaterialsPromise, Elsevier Science, 2001
I
6 A Pandit, Haemostaticwound dressings, Us Patent Office, Pat No. 5 836 970. November 1998.
7 S M Cole and D L Nelson, Alginate wound dressing of good integrity, US Patent Office, Pat No. 5 197 945 March 1993.
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8 H Tarnura, Y Tsuruta and S Tokura, Preparation of chitomcoated alginate filament, Materials Science and Engineering, 2002 C20 (1 -2) 143-147.
9 C J Knill, J F Kennedy, J Mistry, M Miraftab, G Smart, M R Groocock and H J Williams, ‘Alginate fibres modified with unhydrolysed and hydrolysed chitosan for wound dressings’, Carbohydrate Polymers, Jan 2004 55 issue 165-76. 10 M MiraRab, G Smart,J F Kennedy, C J Knill, J Mistry and M R Groocock, Medical Textiles and Biomaterials for Healthcare, pages 37-66, Woodhead Publishing Limited, 2006.
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ANTIMICROBIAL TEXTILES FOR HEALTH AND HYGIENE APPLICATIONS BASED ON ECO-FRIENDLY NATURAL PRODUCTS M Joshi, R Purwar, S Wazed Ali Department of Textile Technology, Indian Institute of TechnologyyHaw- Khas, New Delhi 110016, India
62 S Rajendran Institute for Materials Research and Innovatioq The University of Bolton, Deane Road Bolton BL3 5AB,UK ABSTRACT The paper gives a comprehensive review of antimicrobial finishing of textiles using ~ t u r a l products such as chitosan, natural dyes and other herbal products. The research work on antibacterial finishing of cotton textiles using the active ingredients of neem seed extract, a n a W herbal product, is also presented. Neem tree, abundantly found in Indian subcontinent, is a rich source of medicinal compounds. Neem seed extract has been successfully integrated to the cellulosic substrate imparting a semi-durable antibacterial property against both Gram-positive and Gram-negative bacteria.
INTRODUCTION Antimicrobial textiles with improved functionality find a variety of applications such as health and hygiene products specially the garments worn close to the body and several medical applications such as infection control and barrier materials etc. In the last few decades, with the increase in new antimicrobial fiber technologies and the growing awareness about cleaner surroundings and healthy lifestyle, a range of textile products based on synthetic antimicrobial agents such as triclosan, metal and their salts, organometallics, phenols, quaternary ammonium compounds etc. have been developed and quite a few are also available commercially [l]. The synthetic antimicrobial agents are effective against a range of microbes and give a durable effect on textiles but they possess limitations in use such as associated side effects, action on nontarget microorganisms and water pollution. Therefore, there is still a great demand for antimicrobial textiles based on eco-friendly agents which not only helps to reduce effectively the ill effects associated due to microbial growth on textile material but also comply with the statutory requirements imposed by regulating agencies. The use of ~ t u r aproducts l such as chitosan [2] and natural dyes [3-4]for antimicrobial fhishing of textile materials has been widely reported. Other natural herbal products such as Aloe Vera, Tea Tree oil, Eucalyptus oil, Tulsi leaf (Ocimum busilicum) extracts etc. can also be used for this purpose, as there is a vast source of medicinal plants with active antimicrobial ingredients Although, there are many natural products rich in antimicrobial agents but the work on the exploration of their use in textiles is very limited and not well documented. The relatively lower incidence of adverse reactions to herbal products compared to modem synthetic phaceuticals, coupled with their reduced cost, can be
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exploited as an attractive ecdiiendly alternative to synthetic antimicrobial agents for textile applications. This paper gives a comprehensive review of antimicrobial finishing of textiles using natural products as reported in the current literature. The research work done by our group on antibacterial finishing of cotton and cottodpolyester blend textiles using the active ingredients of neem seed extract, a natural product is also presented. Neem tree (4zaairachta indicu),abundantly found in the Indian subcontinent is a rich source of medicinal compounds [5]. It has an excellent potential as antimicrobial agent and its main constituents such as azadirachtin, salannin and meliantriol are proven insect growth regulator and antifeedent Neem seed and bark extracts have been successfully integrated to the cellulosic substrate imparting a semi-durable antibacterial property against both Gram- positive and Gram-negative bacteria.
NATURAL ANTIMICROBIAL AGENTS FOR TEXTILE SUBSTRATES In the present scenario of environmental consciousness, the new quality requirements not only emphasise on the intrinsic functionality and long service life of the product but also a production process that is environmental friendly. Therefore, research on environmental friendly antimicrobial agent based on natural products for textile application is gaining worldwide interest. A brief review based on the recent literature describing various natural products being explored for imparting antimicrobial properties to textile material is presented in this section. Chitoran
Chitosan (ply (1-4) 2 amino 2-deoxy p-D glucan), a deacetylated derivative of chitin is a natural, non-toxic, microbial resistant and biodegradable polymer. Chitin is one of the most abundant polysaccharides found in nature, derived from ma.rinc shells and mollusks. Antifungal or antimicrobial properties of chitosan are believed to originate h m the polycationic nature of chitosan that can bind ~ t anion h site in proteins thus resulting in selective antimicrobial activity towards fungi or bacteria. The antimicrobial activity of chitosan is influenced by number of factors that include the type of chitosan, the degree of deacetylation, molecular weight and other physicochemical properties. The antiobacterial activity of chitosan is also sensitive to pH, with higher activity at lower values (pKa 6.5). Chitosan and its derivatives have received a lot of attention as an antimicrobial agent for use in textiles [2]. Chitosan can be attached chemically on to the cotton fabric by using crosslinking agents like glutaric dialdehyde [6] and polycarbxylic acids [79].Chitosan is applied onto the fabric by padding the cotton fabric with a mixture of chitosanand citric acid followed by hi& temperatme curing. Chitosan citrate has been used as a non formaldehyde based durable press finish having antimicrobial properties [lo]. Chito oligosaccharides, on the other hand, have been applied onto the cotton fabric d t h or without a binding chemical such as crosslinking agents to impart durable antimicrobial properties [1I]. Shin and coworkers [ 121 used water soluble chitosan oligomers prepared by acid degradation for finishing polypropylene nonwoven fabrics to impart antimicrobial activity against P.vulguris,S.aureus and E.coli. at 0.01 % and 0.05 % level. A chitosan derivative (HTCC) N42 hydroxyl) propyl-3-trimethylammonium chitosan chloride has been used as an additive during polyacrylonitrle (PAN)spinning. A small amount of this additive imparts good antistatic and antimicrobial property to acrylic fibres [13]. Chitosan
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has been reported as a binder and thickener for pigment printing of polyester and polyesterlcotton blends. The prints show a 96% reduction of S. m e u s colonies within one hour of activity [ 141. Fibres made from chitosan are also available commercially. Chitosan can be considered as a multifhctional textilefinishing agent because its antimicrobial activity can be combined with other functions slch a dyeing improvement, antistatic and deodorant activity. However, the major limitations in its application on textiles include: - it is effective against microorganisms only at higher concentrations and forms a film on the surface of the fabric which decreases the air permeability; and the fabric becomes stiff after its application.
-
Silk sericin is a natural macromolecular protein derived from silkworm, Bombyx mori and constitutes 25-30% of silk protein. It envelops the fibroin fibres with successive sticky layers that help in the formation of cocoon. Most of the sericin is removed during raw silk production at the time of reeling and other stages of silk processing and discharged in the effluent causing water pollution. However, Sericin is a biomolecule of great value as it has antibacterial, UV resistant, oxidative resistant and moisturizing properties. The recovery of silk sericin from degumming liquor or waste cocoons reduces the environmental pollution, finds applications in creams and shampoos as a moistmizing agent and used as an important biomaterial agent for several applicationsincluding textiles [151. Functional properties of some synthetic fibres can be improved by coating with silk sericin protein. Sericin modified polyester have been reported by Yamada & Matsunaga [ 161 and Wakabayashi and Sugioka [17]. The serichmodified polyester is five times more hydroscopic than untreated polyesters. Although, sericin application on textiles for antibacterial property enhancement has not been reported as yet, but it has a potential for such an application and our group is exploring the same.
Neem extract Neem (Azadirachta indica), an evergreen tree of India, belongs to the plant family Meliaceae (mahogany). It has been recognized as om of the most promising sources of compounds with insect control, antimicrobial and medicinal properties [181. In India, neem has been in use since ancient times as a traditional medicine against various human ailments and about 700 herbal preparations based on neem are found in Ayurveda, Siddha, Unani, Amchi and other local health prescriptions. Neem has also received a lot of attention worldwide for its potential use as an herbal pesticide and other healthcare formulations in counties such as China, USA, France, Germany, Italy etc. The medicinal value of neem has been recognized by the U S National Academy of Science who published a report in 1992 entitled, “Neem-A Tree of Solving Global Problem”. The active ingredients of neem are found in all parts of the tree but in general, seed, bark, leaves and roots are mostly used for extraction purpose. More than 300 different active compounds have been reported h m different parts of neem tree but the most important limonoids are azadjrachtin, salannin and &dim [191. The neem extract has been widely used in herbal pesticide formulations because of its pest repellent properties. It
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should be mentioned that the active ingredients of neem extract is also used to inhibit the growthof Gram Positive and Gram negative bacteria. Currently, little work has been published on the application of neem in textiles as an antimicrobial agent. Few patents based on the application of neem oil by micm encapsulation technique have been recently reported [20]. A systematic stu& on integrating neem seed and bark extracts on to the textile substrates has been undertaken by our p u p at IIT Delhi in the last five years [21], and the major findings are described briefly in this Paper.
Other herbal products Many natural dyes obtained h m various plants are known to have antimicrobial properties. Punica granatum and many common natural dyes are reported as potent antimicrobial agents owing to the presence of a large amount of tannins. Several plant dyes which are rich in naphthoquinones such as lawsone from henna, juglone from walnut and lapachol from alkamet are reported to exhibit antibacterial and antifungal activity.Gupta el al. [3-4] have studied the antimicrobial properties of eleven natural dyes against Grampositive and Gram-negative bacteria. They found that the antimicrobial efficacy of a dye would vary when it is present in solution and when it is held intimately by a textile substrate. Hence, the textile material impregnated with these natural dyes showed less antimicrobial activity as uptake of these dyes on textile substrate is below the minimum inhibitory concentration The antimicrobial activity of dyes depends mainly on their chemical structure specifically the active functional groups present. It has been established that the presence of tannins is responsible for antimicrobial activity of most of these natural dyes. Tannins are natural occurring polyphenols which are water soluble and found in many plant species as well as trees, accumulated in parts such as bark, wood, leaf, roots or fruits up to 10% by dry weight. Tannins possess antimicrobial activity against a wide range of bacteria, fungi etc [22]. Turmeric or cumin a yellow florescent pigment extracted fiom rhizomes of several species has been used as a colomt for dyeing of wool, silk and unmordanted cotton. Being a well-known antimicrobial agent since ancient time, turmeric imparts antimicrobial property to textile substrates. A recent study on the application of Hiba oil (cypress oil) as an antimicrobial Gent for textiles has been reported [23]. The antimicrobial activity of other plant extracts such as pepper (ally1 thiocyanate AITC), prickly chaff flower (Achysanthus aspera), tulsi leaves (Osmium basilicum) and pomegranate rind (Punica granatum) have also been explored for textile applications [24]. Aloe Vera (Aloe barbadensis, Miller), belongs to the family Liliaceae, has been used in traditional medicinal practices such as healing of wounds and burns and finds uses for medical and cosmetic purpose as w l l as for general health [25]. Aloe Vera also possesses antihgual and antibacterial activity, which can be exploited for medical textile applications such as wound dressing, suture,bioactive textiles etc.
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ANTIMICROBIAL FINISHING OF TEXTILES BASED ON NEEM EXTRACT Material8 and metbod: A desized, scoured and bleached plain weave cotton fabric weighing 130 gm/& was used throughout the study. Glyoxal (from ThomasBaker), 1,2,3,4-butane tetracarboxlic acid (BTCA) and citric acid (from Qualigens) were used as crosslinking agents. Aluminium sulphate (Merck) as catalyst, Tartaric acid (Merck) as catalyst activator and Ethylene Glycol (Merck) as cereactant additive were used for Glyoxal crosslinking. Sodium Hypophosphite (Loba Chemie) was used as a cctalyst for carboxylic acids. Neem seed extract (NEEMAZAL Technical @) was procured h m E D Parry (I) Ltd. Bangalore. All the chemicals were of reagent grade. Neem seed extract (10% w/v) was applied on to the cotton and cotton polyester blended fabrics abng with crosslinking agents using paddrycure method. The conditions for finishing of cotton fabric are given in Table 1.
Table 1: Particulars of Fabric Finishing Code
Substrate Crosslinking agent
Catalyst and other additives
C-G
Cotton
Glyoxal(ll.6 Aluminum sulphate (4% ow), 85"C,Smin 120°C, %) tartaric acid (4% ow), Ethylene min Glycol (12SYo)
2
C-B
Cotton
BTCA (6 YO) Sodium Hypphosphite (4.1%)
3
Process Parameters Drying
curing
85OC, 5min 160°C, min
C-C
Cotton
Citric Acid Sodium Hypophosphite (4.1%) (6Yo) * Neem seed extract concentration- 10% w/v
85"C, 5min 160°C,
3
min
The finished fabric was washed in a launder-0-meter according to AATCC Test Method 61-1975, under test I1 A, using non-ionic detergent, Lissapol N. The antibacterial activity of the fabric samples was tested using AATCC Method 100 using StuphyIococcus uureus. The fabric swatch (l"x1") was placed in a sterilized flask containing Luria broth (Hi-media) solution, inoculated with 20 p1 of test organisms and incubated at 37°C for 24 hrs in a laboratory shaker at 200 rpm. After incubation the number of colony forming unit (CFU) was counted by using serial dilution method. Results and discussion Neem seed extract has been applied on to the cotton fabric using different croslinking agents described in Table 1. The antibacterial activity of the finished fabrics was evaluated quantitatively against Grampositive bacteria StuphyIococcus uureus. Table 2 shows the antibacterial activity of seed extract treated fabric with variouscrosslinking agents after one wash. It has been found that seed extract with various crosslinking agents showed excellent (more than 99%) antibacterial activity againstStcphyZococcus uureus. The control samples also showed some activity against the tested bacteria.
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Table 2: Antibacterial Activity of Seed Extract Treated Fabrics after Code Untreated Control I Control Il Control Ill C-G C-C C-B
Samples
b' Wash
Antibacterial Activity (%)
Cotton Cotton + GlyoxaY Glycol Cotton + Citric acid Cotton + BTCA Cotton + Glyoxal/ Glycol + Seed Extract (lO%w/v) Cotton + Citric acid + Seed Extract (10% w/v) Cotton + BTCA+ Seed Extract (10% w/v)
42.0 13.0 18.0 99.9 99.0
99.5
Figure 1 shows the effect of washing on antibacterial activity of the seed extmt treated fabric with various crosslinking agents. There is a slight drop in antibacterial activity of seed extract treated fabric with BTCA and Glyoxdglycol after five washes and sharp drop in antibacterial activity after 10 washes. Cotton fabric finihed with neem extract along with citric acid showed continuous decrease in antibacterial activity as the washing progressed. Neem extract treated fabric with BTCA retains its antibacterial activity of 40% after 10 washes.
Figure 1: Durability of Antimicrobial Activity of Seed Extract Treated Fabrics The results indicate that the active ingredients of seed extract are attached to the fabric via the crosslinking agent. The crosslinking agent acts as a bridge between the active ingredients of neem and cotton fabric. The decrease in antimicrobial activity of seed extract f ~ s h e fabric d after ten washes may be due to the deterioration of crosslinking effect due to repeated washing.
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Thus, neem seed extract finished fabric imparts effective antibacterial activity to the cotton fabric which is durable up to five machine washes which is equivalent to twenty five home launderings. CONCLUSION This review demonstratesthe applicationof natural antimicrobial agents, which an be used for imparting antimicrobial activity to textile substrates. Although many reviews deal with eco-iiiendly bioactive natural products for textile applications, only few studies have been systematicallycarried out to demonstrate the antibacterialactivity.The major challenges in using the natural products as potential antibacterial agents to textiles are that most of the ingredients are complex mixtures of several natural compounds and their composition of active ingredients varies between speciesof the same family. The activity and composition also varies depending on their geographical location, age and method of extraction. The availability of these products in bulk quantities, complex extraction, isolation and purification procedures to standardize the products and stability of extracts under various processing conditions are also noticeable challenges in using the natural antibacterial products for textile applications. The durability and antimicrobial efficiency over a range of bacteria are other major issues, which receive attention for fbrther active research in this area. However, because natural products are ecefriendly and non-toxic, they are still promising candidates for niche applicationssuch as medical and healthcare textiles.
Acknowledgement8 The authors wish to acknowledge the kind support of Dr. S S Pillai (Vice President) and Dr. S Rao D (Scientist, Natural products Division) of E I D Parry (I) Ltd, India for their kind support in providing Neem seed extract - the Neemazal Technic& for this research work. REFERENCES 1 R Purwar and M Joshi, ‘Recent developments in antimicrobial finishing - a Review’, AATCC Review, 2004 4 2 1-24. 2 S H Lm and S M Hudson, ‘Review of chitosan and its derivative as antimicrobial agent and their uses as textile chemicals’, J of Macromolecular Sci, Po& Rew, 2003 C43 223269. 3 D Gupta, S K Khare and A Laha, ‘Antimicrobial properties of natural dyes against Gram negative bacteria’, Coloration Technology2004 120(4) 167-171. 4 D Gupta,
R Singh, A Jain, S Panwar and S K Khare, ‘Antimicrobial activity of some natural dyes’, @es and Pigment, 2005 66(2) 99-102. 5 A Chatterjee and S Pakashi, The Treatise on Zndian Medicinal Plant, 1994 3 76.
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6 Z Zhang, L J Chen, Y Haung and D Chen, ‘Antibacterial properties of cotton fabrics treated with Chitosan’, Tex Res J, 2003 73(12) 1103-1106. 7 Y S Chug, K K Lee, J W Kim, ‘Durable press and antimicrobial finishing of cotton fabrics with a citric acid and chitosan treatment‘, Ten Res J, 1998 68(10) 772-775. 8 S H Hsieh, Z K Haung, Z Z Haung, Z S Teng, ‘Antimicrobial and physical properties of woolen fabrics cured with citric acid and chitosan’, J of Appl Polymer Sci, 2004 94 1999-
2007. 9 A S Aly, A Hashem, S S Hussein, ‘Utilization of chitosan citrate as creaseresistant and antimicrobial finishing agent for cotton fabric’, Indian J of Fibre and Tex Res, 2004 29(2) 218-222. 10 H S Seong, J P Kim,S W KO,‘Preparing chitwligosaccharides as antimicrobial agents for cotton’, Ten Res 4 1999 69(7) 483-488. 11 J W Lee, C W Nam,S W KO,J of Korean Fibre SOC,1999 36 769. 12 Y Sin, D Yoo, K Min, ‘Antimicrobial f ~ s h m gof polypropylene nonwoven fabric by treatment with chitosan oligomer’, JofApp Polymer Ski, 1999 74 2911-2916. 13 C W Nam,Y H Kim, S W KO,‘Modification of polyacrylonitrile (PAN) fiber by blending with N-(2-hydroxy)propyl-3-trimethyl- ammonium chitosan chloride’, J of App Polymer Sci, 1999 74 2258-2265. 14 S K Tiwari, K G Prajapati, M M Gharia, ‘Pigment prints with antibacterial characteristics’, Colourage, 2001 48(9) 17-20. 15 Y Q Zhang, ‘Application of natural silk sericin in biomaterials’, Biotechnology Advances, 2002 20 91-100.
16 H Yamada, A Matsunaga, Synthetic fiber woven or knitted fabric improved in hygroscopicity. Japan Patent 06-O17373A, 1994. 1 7 S Wakabayashi, M Sugioka, Synthetic fiber improved in hygroscopicity. Japan Patent 06-017372A, 1994.
18 R P Singh, M S Chari, A K Raheja, and W Kraus Neem and Einironment, Oxford & LBH Publishing, New Delhi, India 1996.
19 H Schmutter, The Neem Tree: Source of Unique Natural Products For Integrated Pest Mmgement, Medicine, Industry and other Purpose, V C H , Weinheim, Germany, 1995.
20 R b a r , Antibacterial Finishing of Cotton Textiles using Neem Extracts, PhD Thesis, IIT New Delhi, India 2005.
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2 1 C Nathalie, Method for acaricidal and microbicidal treatment of textile materials, Patent No. WO 03002807,2003.
22 A Scalbert, Antimicrobialproperties of Tannins,Phytochemishy 1991 30 3875-3883. 23 H Nakashima, Y Onji, T Takatuka, Analysis of thujopsene in antimicrobiaVdeodorant processed textiles as an index of hiba oil, Sen’I Gakkaish, 2003 59 145-152.
24 H Nakamura, K Kobayashi, T Koshiba, I My&, M Barada, Antibactreial finishing of cotton fabric by natural products, Kenkyu Hokoh To@ Toritsu Sangyo Gijustu Kenkyzuho2002 5 161-162. 25 D J D Rodriguez, D H Castillo, R R Garcia and J L A Sanchez, A n h g a l activity in vitro of Aloe Vera pulp and liquid fraction against plant pathogenic fimgi, Industrial Crops and Products 2005 21 8 1-87.
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INVESTIGATION OF THE FILTRATION PROPERTIES OF MEDICAL MASKS M, Akalin, I Usta, D Kocak and M S Ozen Technical Education Faculty, Textile Department, Marmara University, Istanbul 81040, Turkey
ABSTRACT Medical masks are mostly produced from textiles. Weaving, knitting and nonwoven technologies are used to produce masks. But, nowadays, nonwoven technology is preferred for the mask production method. Nonwoven surfaces has good filtration properties. Mostly polyester and polypropylene fibers are used for mask production. Medical masks are designed to enable different functions. Generally masks have to protect from virus, bacterias, biological substances and particules in the air. Medical masks enable all these properties and produced according to application field. This is the first and initial results of the medical filtration project carried out by the authors. In this study particule filtration properties of different masks have been investigated. For each mask smallest particule size filtrated from the air accepted as the base for the comparison.
Key Words: Mask, atration, reaspiration, medical INTRODUCTION The main purpose of the mask is to prevent the distribution of enfected particules. Other function of the mask is to protect the user from liquids and particules. These two function is important for the mask design. Execpt classic masks too many functional masks can be found. Functoinal masks are used to control the viruses. Most of the viruses are smaller than 1 micron. So classic masks are not effective for the filtration of viruses. Nonwoven production methods are used to produce classic masks. Polypropylene fiber is used because of its nonabsorber properties for the basic medical masks. Polypropylene fiber does not absorb the humidty. The surface of the fibers collect the humidity and particules. Humidity transfer can not be prevented effectively. By using these masks for a long time viruses and particules pass from the filter and enter to body. The filtration efficiency of a mask is discribed as capacity of holding particules and viruses in the air. Filtration efficiency is determined as efficiency ratio and contains particule size, filtrated air quantity and using time. In this study filtration efficiency of basic medical masks were investigated.
MATERIALS AND METHOD In this study 6 different masks which are used by Marmara University Medical School Health Personnel were! investigated. Experiments were carried out in normal conditioned laboratory which have particules. Technical properties of the masks are given in Table 2. Experiments were carried out according to human breathing capacity for normal conditions 4OL/min and for rapid conditions 85L/min. NaCl particules were used to determine the filter efficiency, particules sprayed to masks in 40Wmin and 85Wmin velocity. Filtering performance of the masks were 0 Woodhead Publishing Limited, 201 0
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determined according to particule weight, particule size and number of particules in cm'. Table 1. Technical properties of masks Masks Properties A B C D E F Maierial PP PP PP PP PP PP Production method Spun-lace Spun-lace Spun-lace Spun-lace Spun-lace Spun-lace Fiber fineness, dtex 3 3 3 3 3 3 Thickness, mm 0,3 1 0,17 0,21 0,31 0,23 0 3 Fabric weight, 28,l 26,3 23,5 50,7 30,8 29 g/m2 Porosity, pm 44 31,4 79,7 63 38 52,8
RESULTS Photographs of the masks were taken before and a.f€erthe tests by Projektina projection microscope. The photos are shown in Figure 1. As can be seen from the photos after low velocity spray, masks collected more particules.
B - (Unused mask filter) .. _______
.
,
-
".&-.A-
C - (Unused mask filter)
-___
CI - (Used mask filter)
94
C2 -(Used mask filter)
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CI
-
(Used mask filter)
C2 -(Used mask filter)
I: - (Ilnuscd mask filter)
I
- (Unuscd mask liltcr)
1-1 - (IJsed mask Iiltcr) ~
Figure 1. Unused and used masks( 1: used with 40L/min, 2: used with 85Umin) Results obtained from the study were determined according to particule weight, particule size and number of particules in an2.Results are given in Figure 2,3, and 4. Results were evaluated according to two spray velocity.
350 300
E
250 3 200
a# a#
5
150
-z
100
; 5c
I~~
A
8
C
D
E
F
Masks
Figure 2. Particule weight collected by the masks according to 40Llmin and 85Ll1nin spray velocity As seen in Figure 2, the lowest particule weight is obtained by masks B and E. The highest values are obtained by mask D.
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C
B
A
0
E
F
Marks
Figure 3. Number of particules collected by the masks according to 40Umin and 85Umin spray velocity
As can be Seen h m the Figure 3, Mask B and E collected the lowest particules in square centimeter. Particule holding performance decreased by increasing spray velocity from 40Umin to 85L/min.
A
B
C
D
E
F
Masks
Figure 4. The smallest particule size collected by the masks
In Figure 4 the smallest particule size is given in micron. Masks B, D and E collected the smallest particules. CONCLUS~ON All masks have showndifferent behaviours to NaCl particules according to their
porosity given in their technical properties. Porosity, filter thickness and weight effects the particule weight collected by the masks. For example porosity of mask A is nearly same as the mask B and E, but mask A collected more particules because of its filter thickness. By increasing the spray velocity number of particules and particule weight collected decreased. It is very clear that porosity of the filter effects the number of particules and particule weight collected. By increasing the spray velocity, small particules passes fiom the pores but bigger particules collided to the filter and scattered. Also pore sizes effects the smallest particule sizes collected by the masks.
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As a result basic medical masks can filter the particules which is bigger than 25 micron according to filter thickness and porousity. These basic medical masks can not be used for the 111protection fiom the viruses. Filtration properties are effected by the nonwoven fabric production properties. For the filtration purposes depending on the size of the particulate to be filtered, fabric thickness plays quite important role moret than other properties. REFERENCES 1 J Derric, C Gomersall, ‘Protecting healtcare staff from severe acute respiratory syndrome: Filtration capacity of multiple surgical masks’, J Hosp Infecr, 2005 59(4), 365-368. 2 D Cyranoski, ‘Masking our ignorance’, Nature, 2005 26 435(7041) 408. 3 C Chen, K Willeke, ‘Characteristics of face seal leakage in filtering face pieces,’ Am IndHygAssoc J , 1992 53 533-9. 4 C Huang, K Willeke, Qiany, S A Crinshpun, V Levicius, ‘Method for measuring the spatial variability of aerosol penetration through respirator filters,’ Am Ind Hyg Assoc J 1998 59 461-5. 5 Y Qian, K Willeke, V Ulevicius, S A Grinshpun, ‘Particle reentrainment f?om fibrous
filters’, Aerosol Sci Tech, 1997 27 394-404. 6 Y Qian, K Willke, S A Ginshpun, J Donnelly, C C Coffey, ‘Performance of N95 respirators: filtration efficiency for airborne microbial and inert particles,’ Am Ind Hyg ASSOCJ , 1998 59 128-32. 7 N Mccullough, L Brosseau, D Vesley, ‘Collection of three bacterial aerosols by respirator and surgical mask filters under varying conditions of flow and relative humidity’, Ann O c m p Hyg, 1997 41 677-90. 8 C Coffey, R Lawrence, D Campbell, Z Zhuang, C Calvert, P Jensen, ‘Fitting characteristics of eighteen N95 filtering-facepiece respirators’, J Occup Environ Hyg, 2004 1 262-71. 9 A Rengasamy, Z Zhuang, A R Berry, ‘Respiratory protection against bioaerosols: literature review and research needs’, Am J Infect Control, 2004 32 345-54. 10 Z Wang, T Reponen, K Willeke, S Grinshpun, ‘Survival of bacteria on respirator filters,’ Aerosol Sci Tech, 1999 30 300-8.
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V. K.Kothari and R Logamthan Department of Textile Technology, Indian Institute of Technology, Haw- Khas, New Delhi 110016, India ABSTRACT Wipes are used to clean surfaces and can be used in either dry or wetlimpregnatedform. Disposable nonwoven wipes are increasingly used for diverse personal, household, industrial and medical applications. Global market size of wipes is more than 4 billion USD and is growing rapidly. The major properties desired in a medical wipe material are high absorption, low static and gliding friction, non-allergic characteristics, reasonable life and minimal particle release characteristics along with good cleaning efficiency. Traditionally, many surface wiping products for medical usage have been tissue based or woven. However, increasingly, hydroentangled and airlaid nonwoven fabrics are used for both wet and dry wiping applications.Available wipes differ in their absorbency, abrasiveness, durability, and the amount of lint they leave behind. The particle release characteristics of wipes is a major consideration while selecting wipes for cleanroom and medical uses. The paper discusses the development of an instrument which can measure the particles of different sizes released in the air stream when the wipe is abraded by a friction surface under a known pressure. Wipes placed on a rotary platform are abraded by a 1.5 cm diameter abradent in a top holder. The pressure applied by the holder on wipe can be increased in steps and number of particles of different sizes released per unit volume of the air can be measured at Werent times after starting the experimentsusing a laser based particle counter. Seven commercial wipes of a multinational manufacturer with different fibre content and produced by different nonwoven technologies have been compared for their lint release characteristics under five different loads. In all the wiping fabrics, number of particles of 1, 3, 5, 10, 15, and 20 pm released per liter of air on abrasion were measured at 30 second interval after starting the abrasion. Number of particles of different sizes released by the wipes increased with increasing load and with increasing abrasion time. Correlation analysis has been done to see the interaction effect between load and time of abrasion on the release of particles of different sizes. The equations developed can be used to predict the particle release characteristics of selected wiping nonwoven fabrics. Wipes containing viscose fibres released relatively higher number of particles as compared to airlaid nonwoven wipes. Filament based hydroentangled nonwoven fabrics showed the least particle release characteristics.
INTRODUCTION Wipes are used to clean surfaces and can be used in either dry or wettiimpregnated form. Disposable nonwoven wipes are increasingly used for diverse personal, household, industrial and medical applications. Global market size of wipes is more than 4 billion USD and is growing rapidly. There are some of the application areas where the contaminated environment is undesirable. For example, medical applications, clean room applications, skin care wipes. In such applications we require high level of cleanliness and thus release of particles fiom the wipe used for cleaning the surface is totally undesirable and we need to assess lint release characteristics of the wipes before their use in these applications. The major properties desired in a medical wipe material 98
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are high absorption, low static and gliding fiction, non-allergic characteristics, reasonable life and minimal particle release characteristics along with good cleaning efficiency. Traditionally, many surface wiping products for medical usage have been tissue based or woven. However, increasingly, hydroentangled and airlaid nonwoven fabrics are used for both wet and dry wiping applications. Available wipes differ in their absorbency, abrasiveness, durability, and the amount of lint they leave behind. The particle release characteristics of wipes is a major consideration while selecting wipes for cleanroom and medical uses. This chapter discusses the development of an instrument which can measure the particles of different sizes released in the air stream when the wipe is abraded by a friction surface under a known pressure. Seven commercial wipes with different fibre content and produced by different nonwoven technologies have been compared for their lint release Characteristicsunder five different loads. In all the wiping fabrics, number of particles of 1, 3, 5, 10, 15, and 20 pm released per liter of air on abrasion were measured at 30 second interval after starting the abrasion. DESIGN OF MEASUREMENTAPPARATUS
A cylindrical tube made of transparent acrylic sheet is used as the housing of the set up. One end of the tube is connected to suction pump through an a l d u m connector and a hose. The other end of the tube a glass fibre nonwoven filter is attached to clean the incoming air of all the contaminants before it enters the cylindrical tube. Base plate is used to hold the sample and a motor is attached to it rotate it at 6 rpm. A 24 mm diameter friction surface is fured on the base of the vertical plunger and made to rest on fabric sample. The load applied by the plunger on the fabric surface is 33 gf. Additional loads can be kept on the top of the plunger to change the pressure between the fabric and the fiction surface. The suction pump is used to create air flow inside the cylindrical tube. A particle counter is fitted in the cylindrical tube to count the particles in the air moving out of the cylindrical tube due to suction. The line diagram of the developed setup is shown in Fig 1. The particle count is measured using the ART1 HHPC-6 airborne particle counter. It works on a Light Scattering principle and utilizes a very bright light source generally laser to illuminate the particles. This very bright light source shines through an optical
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Fig; 1. Line diagram of the developed setup block. Within the optical block are mirrors and photo detectors. Sampled air is drawn through the laser beam by a small vacuum pump. As entrained particles in the air pass through the laser beam, the laser light interacts with the particles and is scattered. The scattered light is picked up by mirrors, which focus the scattered light onto one or more photodetectors. The photo-detector converts the burst of light energy fiom each particle into a pulse of electrical energy. By measuring the height of the signal and referencing it to the calibration curve, it determines the size of the particle and by counting the number of pulses, it determines quantity of particles. The particle counts measured in the study are differential counts i.e. the number of particles for the particular particle size implies all particles that are larger than or equal to the particle size selected, but smaller than the next higher particle size in the range of instrument. The particle size for the counter used were 1, 3,5, 10,15, and 20 pm. MATERIALS AND METHODS
Materials Seven different commercial nonwoven wipe samples were used for the study. The details of the nonwoven samples are given in Table 1. Table 1. Sample details Sample s1 S2 S3
S4 s5
S6 S7
Thickness,nun GSM Wipe content 0.13 11 PP 0.29 33 PLA LyoceYPET 0.38 67 P E T M (54/46) 0.80 79 P L m p 0.44 53 P E T M (52/48) 0.40 81 VISRET (70/30) 0.44 62
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Lint releasing property Lint releasing property of the nonwoven wipes was analyzed with the help of the designed experimental setup. Wipes samples of dimension 80 X 80 mm was mounted on the base ring. First the vacuum pump was run for around 30 minutes so that all the particles in the tube gets sucked and air inside gets cleaned. The number of particles at this stage was measured using particle counter. After this the motor was run simultaneously with the vacuum pump and the particle gets released fiom the wipe. The concentrations of the particles were then noted with the help of w c l e counter in the main tube after every 30s. The experiment was repeated for all 7 seven samples with 5 different additional loads (0,20, 50, 70,100 gf) and average of 10 readings were taken. The details of additional load and correspondingpressure values are given in Table 2. Table 2. Details of load and corresponding pressure
Additional load, gf 0 20
50 70 100
TOWload,
fl
33 53 83 103 133
Pressure, Ncm2 18.75 30.00 47.16 58.50 75.57
RESULTS AND DISCUSSION The effect of load on the number of l p particles released after abrasion of 30s and 240s for all nonwoven samples is given in Figs. 2 (a&b) respectively while Figs. 3 (ahtb) gives results for 5pm particles released after abrasion of 30s and 240s. From the Figs. 2 & 3, it is observed that a linear relationship exists between number of particles released and amount of load applied. With the increase in additional load, number of particles released gradually increases and the number of particle release is higher for 1pm particle size than 5pm particle size. It was noted that increase in number of particle release is more pronounced for sample S7 than others. This may be due to the viscose content in the sample S7. The viscose portion of the sample gets abraded easily and results in higher particle release. Due to the presence of wood pulp in the samples S4, S5 and S6, they have relatively higher number of particle release compared to that of samples S l y S2 and S3. This is due to the fact that shorter wood pulp fibres get abraded and released easily. The samples S1, S2 and S5 tear off due to abrasion after certain time because of their lower GSM and thickness. Number of particle released from the samples S1 (PP), S2 (PLA) and S3 (LyocelVPET) is observed to be lower as compared to that from other samples due to the filaments form the structure of these wipes as compared to short fibres in other wipes. These fibres have a good tensile strength, they have a good abrasion resistance which results in lower particle release. Detailed analysis of the data shows that there also exists a linear relationship between number of particles released and amount of abrasion time. With the increase in abrasion period, number of particles released gradually increases and the number of particle release is higher for 1pm particle size than 5pm particle size. 0 Woodhead Publishing Limited, 2010 101
04 0
1
I
I
I
i
20
40
60
80
100
Addbnal Load (gf)
800 700 600 500 400
300
200 100
0
0
20
40
60
80
100
Additional Load (gf)
Fig 2. Number of l p particles released per litre of air after abrasion under different loads after the time of (a) 30s and (b) 240s
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50
. - - .-
45
0
40
35
30 25 20
.-a L
15
_.------ -
-+---_
B
0
_
-
I
-
-
-
-
a
-
-
A
I-'-'--
I 1
0 0
20 20
40
1
60 Addlttonal Load (g9
'6
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I
80
I
100
Number of particles released (P) from the sample when it is abraded with the abradent was assumed to be a function of additional load, gf (x), time, s (y) and particle size, pm (z). P = f (Load, Time, Particle size)
A second order polynomial equation as shown in Eq.1 was assumed in order to find out the regression equation.
P = + al*x+a2*y+a3*z+q*x*x+as*y*y + Q*z*z+a7*x*y + ~ * y *+%*x*z z
(1)
The values of to ag and coefficient of determination (R’) were determined. R2values obtained were not very high. The particle release was correlated with load and time for particle of predefined sue. A second order polynomial equation as shown in Eq. 2 is assumed in order to find out the regression equation.
The values of a0 to a5 and Coefficient of determination (R’) were determined. The values are listed in Table 3. The Coefficient of determination in these cases was higher. This shows that for a predetermined particle size, number of particle release is a function of load and time. Based on Eq. 2, contour plots were plotted for the particle release with respect to load and time. Contour plots of number of particles released for the sample S3 for the particles sizes l p and 5 p n when abraded under different load and different time is shown respectively in Fig.4.
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Table 3. Values of constants, coefficients and R2 for two variable regressions analysis Sample Particle s1
s2
s3
s4
s5
S6
s7
Sue, pm 1
RZ
Values of coeflicieats a0
a1
a1
a3
4
as
13.97
0.69
0.70
0
-0.002
-0.003
0.954
5
1.246
0.063
0.016
0
0
0
0.957
10
-1.577
-0.018
0.085
0
0
0.001
0.955
20
0.439
-0.013
-0.019
0
0
0
0.812
1
1.969
1.243
0.973
-0.004
-0.002
0
0.984
5
0.79
0.073
0.103
0
0
0.001
0.965
10
0.253
0.08
0.026
-0.001
0
0
0.951
20
-0.706
0.009
0.01
0
0
0.001
0.91
1
14.533
2.115
0.582
-0.014
0
0.005
0.982
5
-0.849
0.135
0.082
-0.001
0
0
0.953
10
-0.244
0.021
0.033
0
0
0
0.941
20
-0.543
-0.005
0.007
0
0
0
0.947
1
15.288
1.465
1.028
-0.004
0
-0.002
0.995
5
3.813
0.1 16
0.045
0
0
0
0.984
10
-0.244
0.021
0.033
0
0
0
0.941
20
0.382
-0.039
0.009
0
0
0
0.932
1
72.525
2.473
1.294
-0.013
0
-0.003
0.987
5
5.8
0.273
0.3 11
-0.001
0
0
0.985
10
8.768
0.148
0.12
-0.001
0
0
0.981
20
-0.348
0.052
0.041
0
0
0
0.955
1
79.097
1.96
1.135
-0.01
0
0.002
0.995
5
10.882
0.2
0.144
-0.001
0
0
0.976
10
8.183
0.212
0.067
-0.001
0
0.001
0.927
20
-0.366
0.01
0.052
0
0
0
0.944
1
177.80
2.476
1.52
-0.01
-0.001
0.001
0.995
5
12.957
0.225
0.294
0
-0.001
0.002
0.948
10
9.519
0.412
0.161
-0.002
0
0.002
0.976
20
-0.44
0.082
0.069
-0.001
0
0.001
0.979
0 Woodhead Publishing Limited, 201 0 105
180n1%
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106 0 Woodhead Publishing Limited, 201 0
CONCLUSIONS An experimental set-up for measuring the particle release due to abrasion has been
designed and fabricated. Seven commercial wipes of a multinational manufacturer with different fibre content and produced by different nonwoven technologies have been compared for their lint release characteristics under five different loads. In all the wiping fabrics, number of particles of 1, 3, 5, 10, 15, and 20 pm released per liter of air on abrasion were measured at 30 second interval after starting the abrasion. Number of particles of different sizes released by the wipes increased with increasing load and with increasing abrasion time. Correlation analysis has been done to see the interaction effect between load and time of abrasion on the release of particles of different sizes. The equations developed can be used to predict the particle release characteristics of selected wiping nonwoven fabrics. Wipes containing viscose fibres released relatively higher number of particles as compared to airlaid nonwoven wipes. Filament based hydroentanglednonwoven fabrics showed the least particle release characteristics. The study shows that the amount of particle release is higher for smaller size particles compared to larger particle sizes. With increase in additional load and abrasion time there is a gradual increase in number of particles released for all the particle sizes. The presence of wood pulp and viscose contributes to higher particle release. From the comparison of seven samples, it was observed that the samples S1 (PP), S2 (PLA) and S3 (LyocelWET) have lower particle release ability compared to other wipes samples. Therefore these wipes can be preferred where lower particle release ftom wipes is desired.
0 Woodhead Publishing Limited, 201 0 107
DEVELOPMENT OF ANTIMICROBIAL POLYESTER USING NEEM EXTRACT S. Wazed Ali, B. Gupta and M. Joshi Department of Textile Technology, Indian Institute of Technology, Hauz- Khas, New Delhi 110016, India
ABSTRACT The study focused on the development of high functionality, high value bioactive products of polyester (PET) fabric. Natural antimicrobial agent (Neem seed extract) was used for the antimicrobialtreatment. Neem tree (Azadiruchtuindich), one of the richest sources of biological active compounds, belongs to the Meliaceae (Mahogony) family and is abundantly found in the Indian subcontinent. A large number of products that include herbal medicine, toothpaste, cosmetics, toiletries and pharmaceuticals are now based on Neem derivatives because of its unique medicinal properties. PET surface was activated using techniques like alkali hydrolysis and cold plasma surface modification for generating functional groups on the PET surface to improve the attachment of the active ingredients of Neem extract. Antimicrobial activity was studied for the functionalized finished fabric with and without cross-linking agents. Qualitative (parallel streak method) and quantitative (colony counting method) testing was carried out to measure the antimicrobial activity against Gram-positive (S. aureus, Bacillus subtilis) and Gram-negative (P.vulgaris, E. coli) bacteria. The results showed that the treated fabrics inhibited the growth of Gram- positive bacteria by more than 90% as compared to the untreated ones. Durability study in terms of antimicrobial activity and other performance properties has also been done. Finished fabrics were also characterized by FTIR and TGA. SEM images were used to investigate the percent reduction of bacteria on the finished fabric before and after treatment. TEM analysis was used to investigate the mechanism of of bactericidal action of the Neem active ingredients. Kcywordr: Natural antimicrobial agent, Modification of PET surface, Antimicrobial activity, FTIR, SEM, TEM INTRODUCTION Poly (ethylene terephthalate) (PET) is often used as a basic material in the textile and plastics industries for a wide range of industrial applications including clothing, shoes, bedding, and interior materials for automobiles. The moisture-transport characteristics of such blends and synthetics tend to cause a greater degree of "perspiration wetness" than occurs with fabrics of wholly natural fibers. Additionally, there is a growing volume of literature demonstrating the survival and growth of microorganisms in textiles and their dissemination as a health risk [l-21. The prime considerationrelated to the end use and b c t i o n of an antimicrobial finish on textiles is that it should meet environmental and low toxicity criteria along with its functional properties. Therefore, research on eco-fiiendly antimicrobial agents for textile application is an emerging area. Natural herbal products are attractive alternatives to synthetic agents for imparting antimicrobial properties in textiles as there is a tremendous source of medicinal plants with bioactive agents. Neem extract is one of such type of products extracted from seed, bark or leaves of neem tree (Azadarichta indica) belonging to Mahgony family and 108 0 Woodhead Publishing Limited, 2010
found abundantly in the Indian subcontinent. It has an excellent potential as antimicrobial agent as it has been firmly established that the neem extracts and its main active compounds i.e azadirachtin, salannin and meliantriol are insect growth regulator and antifeedent [3]. Neem also has the potential to inhibit the growth of the bacteria. Few studies have been rcported on antibacterial activity of Neem oil [4-51, bark extract [6-71 and seed extract [8]. The present study focused on the development of antibacterial as well as insect repellent polyester fabric using Neem extract as an antibacterial agent. Since synthetic fibers like polyester has no surface active group like -€OOH, -OH, etc. to have good adhesion with the finishing agent for getting barrier properties against microbes and different types of insects, several approaches for generating functional groups on the d a c e of PET are reported [9-101 such as hydrolysis of PET with a mild alkaline aqueous solution and another is to treat the surfaces with plasma glow discharge. Plasma glow discharge treatment is an effective method for introducing biological molecules to the surfaces of polymeric materials without causing any severe damage to their bulk properties [1 1-121. In the present work, polyester fabric was surface activated by two routes i.e. alkaline hydrolysis and plasma, prior to treatment with antimicrobial agent (neem seed extract). The integration of active ingredients of neem seed extract on surface activated polyester has been achieved either through crosslinking agents like citric acid or BTCA or direct treatment using a HT/HP machine. The antibacterial activity has been tested for the finished fabrics against Gram-positive (Staphylococcus aureus, Bacillus subtilis and Gram-negative (Proteus vulgaris) bacteria using colony counting method (quantitative) (AATCC Test Method 147-1998). The durability of the finished fabric has been checked after 1 , 5 and 10 machine-washes. MATERIALS A plain weave polyester (70 ends X 58 picks) weighmg 80 gm/m2 was used in this study. Neemazal Technical (Seed extract from Neem tree) was used as ~ b a l antimicrobial agent and supplied by EID (Parry) India l d , Bangalore.
METHODS The fabric samples were treated with different concentration of caustic soda (7%, 12% and 20% owf.) using liquor ratio of 1:40 for varying periods of time (30, 40 min etc.) and at two different temperatures (70" C and SO" C) on a constant temperature water bath with stirring. Vacuum RF-plasma machine (Make: Vico) as well as atmospheric pressure plasma was used for lasma treatment of polyester fabric. For vacuum plasma, initial vacuum used was 10-PTorr and the vacuum used during the treatment was 0.2-0.1 Torr. In this plasma system, the excitation frequency of 13.56 M H z was used. Oxygen gas flow maintained during the treatment was 20 SCCM and the power kept at 80W. Surface modified polyester fabric was padded through a two bowl vertical laboratory padder with two dips and two nips to give a wet pick up of 85 5% on the weight of the fabric with or without cross-linking agent. After the padding, Neemazal treated PET fabric was dried at 85°C for 5 minutes and also at 130°C for 2 minutes. The fabric treated along with citric acid and BTCA was dried at 85°C for 5 minutes and simultaneously also cured at 15OoCfor 2 minutes.
*
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RESULT AND DISCUSSION Surface hydrolysis of PET fabric Polyester fabric hydrolyzed with 20% 0.w.f. NaOH (80'C for 30 min) gives remarkable antimicrobial activity of above 94% against Staphylococcus aureus (Gram-positive bacteria) using 10% w/v neem seed extract even after one washing without using any cross-linking agent. Polyester hydrolysed with 7%, 12% owf caustic soda does not give any significant antimicrobial activity with or without cross-linking agent. Hence, polyester hydrolyzed with 20% owf NaOH was used for all the remaining studies. This means more than 5% weight loss is required for getting sufficient polarity and hydrophilicity on the polyester fabric surface.
Antibacterial activity of Neem seed extract (10%) treated hydroiysed polyeater fabric Hydrolysed PET treated with 10% w/v seed extract (without any cross-linking agent) showed antimicrobial activity of 89% and 32% after one washing against Bacillus subtilis and Proteus vulgaris respectively. This is may be due to physical and hydrophobic interaction between the hydrolyzed PET and the neem seed extract, The lesser antimicrobial activity of neem seed extract against Gram-negative bacteria as compared to Gram-positive bacteria is also evident. Table 1. Antibacterialactivity of Neem seed extract (1 0%) treated PET fabric against Bacillus subtilis Samples Tested Bacteria Temperature( OC ) Bacillus subtilis Drying* Curing* Colony Antibacterial forming unit activity (%) Cfilld
Original PET (Control-I)
335x10'
PET hydrolysed by 20 % NaOH (Control-II) Hydrolysed with 20 % NaOH + C L (Citric-acid /NaH2P@&O), 1 Washed(Contro1
340 xi05 85
180
300~10~
10
-nI)
Hydrolysed with 20 % NaOH + C/L (Citric-acid 85 180 55x105 84 /NaH2P02,H20),1Washed Hydrolysed with 20 % NaOH, 85 15 xi05 95.5 Unwashed Hydrolysed with 20 % NaOH, 1 85 37 x105 89 washed [*Drymg and *Curing time 5 min. and 2 min. respectively] Neem treated fabric cured at 200' C for 90 seconds gives more than 55% antimicrobial activity against P.vulgaris even after one wash. This is may be due to the physical entrapment of active ingredients of neem seed extract within the fibre structure due to 110 0 Woodhead Publishing Limited, 2010
higher mobility of the molecular chain at higher temperature just like the disperse dye entrapment in the polyester fibre structure. It is observed that antimicrobial activity of 84% has been obtained after one washing using 10% Neemazal Technical (neem seed extract) along with citric acid as cross-linking agent. But the fabric becomes yellowish to some extent when using citric acid is used as a cross-linkingagent. The durability of antimicrobial activity of neem treated (with or without crosslinking agent) hydrolysed PET fabric was checked up to 8 washing cycles. It was seen that the durability of antimicrobial activity up to 8 wash cycles was more for non citric acid treated samples than with citric acid treated samples. It may be because of citric acid may not be taking part in cross-linking in presence of Neemazal under the conditions used. Moreover, it may act as a blocking agent of polar group created on the surface of the hydrolyzed PET or selectively cross-linking with the hydroxyl or carboxyl group on the polyester fabric. Thus, the attachment of active ingredients of neem seed extract with active groups on activated polyester surface gets hindered.
Use of HT-HP machine for Neemazal application on polyester fabric
There is a possibility that active compounds of neem seed diffuse into the polyester fiber surfaces at higher temperature (more than 100°C), just like the disperse dyes do. This approach was investigated by treating polyester fabric with neem seed extract at 10% concentration under the same conditions as used for dyeing with disperse dyes on a high temperature high pressure dyeing machine (HT/HP d c ) . For the neem application on polyester fabric using glycerin bath beaker (HT/HP) dyeing machine two different heating rates were used. Initially higher rate of heating up to the glass transition temperature (- 9OoC)of the PET fibre followed by a controlled rate of heating was used. Two different time-temperaturecombinations were used.
1
-
120
Unwashed
m 1st washed
2
0 3rd washed
n
u E g
0
40
6th washed
20
4
I
0
Without CA
With CA
Figure 1 Wash durability of Neem seed extract (10%) treated PET fabric (using citric acid as crosslinking agent) in terms of antibacterial activity against B. subtilis From the Table 2 it is seen that the antimicrobial activity is retained up to 8 washes against S.aweow bacteria for sample treated at 1OOOC and 25 minutes. It may be due to the mechanical entrapment of the active ingredients of the neem compounds within the fibre microstructure. During the circulation of the finishing liquor above Tg, the neem active compounds can go through the internal microstructure of the fibre due to the chain mobility in the amorphous region. Therefore, good antimicrobial activity as well as better washing durability has been obtained. But for 12OOC temperature and 45 0 Woodhead Publishing Limited, 2010 111
minutes treatment time, opposite results were obtained. This may be due to the decomposition of active ingredients at comparatively higher temperature for longer treatment time.
Plasma treatment and integration of Nccrarzrl Tecbnicrl on polyester fabric
The surface activated polyester fabrics using plasma treatment, both using low pressure vacuum plasma as well as atmospheric pressure plasma system, were finished with neem seed extract for imparting antimicrobial activity on polyester fabric. Initially, the polyester fabric activated through the three different routes was compared on the basis of their surface energy and ability to absorb a drop of water. Time in seconds to absorb one drop of water as well as surface energy was measured for the untreated, hydrolyzed and plasma modified polyester fabric. It was seen that surface energy has been improved to 66.5 dyndcm from 49.5 dyne/cm for the hydrolysed fabric. For plasma treated samples, s w k e energy increased to more than 71 dynelcm. It was observed that 60 seconds atmospheric plasma treated polyester takes the lowest time to absorb a drop of water. Therefore, this sample was used for the neem seed extract integration with and Without cross-linking agent. Just immediately after the plasma treatment, the samples were used for the subsequent treatment process, as it is reported in the literature that surface energy of the plasma modified polyester decays withtime [13]. Surface activated (60 sec. treatment on atmospheric pressure plasma d c ) polyester fabric was treated with 10% wlv Neemazal with and without cross-linking agent. 6% BTCA and 4.1%catalyst was used for this treatment using pad-dry-cure process. The detail treatment conditions are given in Table 3. It is observed that, antimicrobial activity of BTCA cross-linked neem treated fabric goes down drastically after 3Td washes. Therefore, it can be said that BTCA is not taking part in efficient bonding With the active ingredient of the neem seed extract. On the other hand, plasma modified fabric treated with neem and cured at 130' C gives good antimicrobial activity even after 3d wash The polyester sample exposed to vacuum plasma treatment (for 120 sec) was treated with 10% wlv Neemazal Technical by pad-dry process. Antimicrobial activity of 39% was found against P.vulgaris (Gram-negative)for 1' washed sample. Table 2. Antibacterial activity of alkali hydrolyzed PET fabric treated with Neem seed extract (10%) by HT/HP machine Samples
Tested Bacteria Stap~Iococcusm e u s Bacillus subtilis Colony Antibacterial Colony Antibacterial forming unit activity (%) forming unit activity (%) C f d d CfUJd
Control sample
95 x10'
-
340 lo5
-
Unwashed sample
4 x1o7
96
21 x105
94
13 x107
86
133 xi05
61
112 0 Woodhead Publishing Limited, 2010
1'*washed sample 2ndWashed sample
16 x 1O7
83
146 xi05
57
5" Washed sample
20 x107
79
170 xl0'
50
8" washed sample
35 x107
63
187 xi05
45
Scanning electron microscopy (SEW analysis Antibacterial properties of neem extract treated fabric and the bacterial adherence on to the fabric was examined by scanning electron microscopy (SEM). SEM micrographs in Figure 2, clearly indicates that the Neem extract acts as an effective bactericidal agent on to the fabric and inhibits the growth of bacteria on to the textile surfaces. Table 3. Antibacterial activity of Neem seed extract (10% w/v) treated PET (plasma surface activated) fabric against S. aureus Samples
Tested Bacteria Temperature ( 'C) S. aureous B. subtilis Drying* Curing* Colony Antibacterial Colony Antibacterial forming activity (%) forming activity (%) unit unit (Cfdd) (Cfldd)
Control sample Blank sample Neem + BTCA (1 washed) Neem + BTCA (3'* washed) Neem (w/o cross-linking agent) (1 washed) Neem (w/o cross-linking agent) (3rd washed) Neem (w/o cross-linking agent) (1 washed)
-
350~10~
85
150
308~10~
85
150
85
150
90
2211~10~
130
12
25x107
17
99.7
4x107
86
21x10~
30
95
6 x107
80
35
19x107
37
99.5
3 x107
90
2 6 3 ~ 1 0 ~ 25 18 x107
90
85
1
30 x107
2x107
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Neem (wlo cross-linking 85 130 6Ox1O7 83 14x107 ?gent) (31dwashed) [*Drying and *Curing time 5 min. and 2 min. respectively]
54
Transmidon electron microscopy 0analysis Transmission electron microscopy has been used to study the mode of action of neem extracts on the Gram-negative bacteria namely E. coli. It has been found that the neem seed extract disrupts the cell wall of the E. coli and the cytoplasmic content leaked out h m the cell, thus the bacteria die and further growth is inhibited. To observe the bactericidal mechanism, 314'b of the minimum inhibitory concentration of Neem seed extract at Werent treatment time was studied. From the Figure 3(a) it is seen that the shape of the original bacteria is almost round and distinct cell wall is observed when no treatment is given. After 6 hours treatment the shape of the bacteria changes and after 16 hours treatment, cell wall starts disintegrating and internal cytoplasmic material comes out gradually. After 24 hours it is clear that most of the bacteria are dead and all the cytoplasmicmaterial leaks out of the cell.
Figure 2 SEM picture of bacteria adhesion on untreated and hydrolyzed Neem seed extract treated (by HT/HP method) PET (washed sample)
Figure 3 TEM pictures of E. coli (a) Without Neem extract (b), (c) and (d) expose to 7.5 mg/ml Neem extract for 6,16 and 24 hrs. respectively
CONCLUSION Polyester fabrics need to be surface activated either through alkaline hydrolysis or plasma treatment prior to their treatment with antimicrobial finishing agent i.e. neem 114 0 Woodhead Publishing Limited, 2010
extracts. More than 5% weight loss by hydrolysis is required for surface functionality required for attachment of neem seed extracts on Polyester fabrics. Plasma treated polyester attains more surface energy than hydrolyzed polyester under the treatment conditions used. Different types of cross-linking agent used in this study were not able to attach the active ingredients of neem seed extract on surface activated polyester via crosslinkinghonding. Surface activated polyester fabric treated directly under high temperature (85-130’ C) with neem seed extract gives better antimicrobial activity in terms of durability. Neem seed extract applied using HT/HP machine under the condition used for disperse dyeing gives the best antimicrobial activity and washing durability. Although surface energy is higher for plasma treated polyester than hydrolyzed polyester, still neem treated hydrolyzed polyester offers better antimicrobial property than plasma activated polyester. There is no significant change in tensile strength and bending length of the neem seed extract treated hydrolyzed polyester fabric as compared to control sample. It has been observed that neem seed extract is more effective against gram-positive bacteria than gram-negative bacteria SEM micrographs indicate that the neem seed extract acts as an effective bactericidal agent on fabric and inhibit the growth of bacteria on to textiles. TEM images reveals that disintegration of E. coli bacteria by active ingredients of neem seed extract is due to the gradual deformation of the cell wall and leakage of the cytoplasmic material due to cell wall rupturing. Thus polyester based textiles can be imparted effective antibacterial functionality using ecofiiendly neem seed extract.
ACKNOWLEDGEMENT The authors wish to acknowledge Dr. S S Pillai (Vice President, Bio products) and Dr. Gopinath (Head, R & D), Natural Product Division from M/s E D Parry (India Ltd. for their kind support in providing Neem seed extract - the Neemazal Technical for this research work.
h
REFERENCES 1 J N Baumgartner, C Z Yang and S L Cooper, ‘Physicalproperty analysis and bacterial adhesion on a series of phosphonated polyurethanes,’ Biomaterials, 1997 18 (12) 83137. 2 S Minami, Y Okamoto, S Tanioka, H Sashiwa,H Saimoto, A Matsuhashi, and Y Shigemasa, In Carbohydrates and Carbohydrate Polymers Yalpani, ATL Press: Mount Prospect, IL 1993 141. 3 A J Mordue and A Blackwell, ’Azadirachtin:an update,’ Journal of Insect Physiology, 1993 399(11) 903-24.
4 S C Chaurasia and P C Jain, ‘Antibacterialactivity of essential oils of four medicinal plants’ Indian Journal of Hospital Pharmacy, 1978 15(6) 166-68. 5 V K Rao, I Singh, P Chopra, P C Chhabra and G Ramanujal, ‘In vitro antibacterial activity ofNeem oil,’ Indian Journal ofMedicinaI Research, 1986 84 (9) 314-16.
6 B K Almas, ‘The antimicrobial effects of extracts of Azadirachta indica (neem) and Salvadorapersica (arak) chewing sticks,’ Indian Journal of Dental Res Jan, 1999 10 23. 0 Woodhead Publishing Limited, 201 0 115
7 P 0 Okemo, W E Mwatha, S C Chhabra and W Fabry, ‘The kill kinetics of Azadirachta hdica a juss. (Meliaceae) extracts on staphylococcus aureus, escherichia coli, pseudomonas aeruginosa and cmdida albicans’ Afiicun Journal of Sci and Tech, 2001 2(2) 113-18. 8 E Coventry and E J Allan, ‘Microbiological and chemical analysis of neem (Azadirachta indica) extracts: new data on antimicrobial activity,’ Phytopurusitica, 2001 29(5) 441-50. 9 Y Ito, G Chen and Y Imanishi, ‘Enhancement of cell growth on a porous membrane co-immobilized with cell growth and cell-adhesion factors,’ Biotechnol Bioeng 1997 18 197-202. 10 Y J Kim, I K Kang, M W Huh and S C Yoon, ‘Surface characterization and in vitro blood compatibility of poly (ethylene terephthalate) immobilized with insulin and/or heparin using plasma glow discharge,’ Biomuteriuls, 1999 21(2) 121-30. 11 J Piglowski, I Gancarz, J Staniszewska-Kus, D Paluch, M Szymonowicz and A Konieczny, ‘Influence of plasma modi6cation on biological properties of poly(ethy1ene terephthalate),’ Biomuteriuls, 1994 15(11) 909-16.
12 N P Desai, J A Hubbell, ‘Biological responses to polyethylene oxide modified polyethylene terephthalate surfaces,’ JBiomed. Mater Res, 1991 2 5 0 829-43.
13 B Gupta, J Hilborn, Ch Hollenstein, C J G Plummer, R Houriet and N Xanthopoulos, ‘Surface modification of polyester films by RF plasma’ J of Appl Polym Sci, 2000 78(5) 1083-91.
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FIXATION OF CATIONIC ANTIBACTERZAL PRODUCTS BEFORE DYEING: A MORE ECOLOGICAL PROCESS R.V. Vieira, J.G. Santos, G.M.B. Soares and J.I.N.R. Gomes Department of Textile Engineering, University of Minho, G M e s , Portugal
ABSTRACT With the vulgarization of antimicrobial treatment of textile fabrics, simple methods to quantify the evaluated the link efficacy, and durability performance will be needed. The biological tests are usually inexistent in textile plant and their specific requisites allow that need to be made by controlled biological laboratories out of textile facilities. The knowledge of textile dyeing processes was applied to the control of cationic antimicrobial applications. The exhaustion profile of a direct dye with lower affinity was used to evaluate the concentration of bonded cationic antimicrobial agent on cotton material. Only bonded agent lasted throughout the dyeing process, transforming this process as a quick simultaneous evaluation of the nature of the bond between agent and fibre.
INTRODUCTION Natural fibres have terminal groups in their polymer structure that make them appropriate for anchoring other groups with specific functional properties. The most used dyes so far based on this approach are reactive dyes for cellulosic fibres, discovered as far back as 1956. Twenty to thirty years on, other products were attached to cellulosic fibres in order to increase the yield of reactive dyes or dyeing with reactive dyes without the use of salt. The reactive dyes possess cationic groups that attracted the anionic dyes used. This process didn't progress much into industrial application, mainly because of non-uniformity of colour problems. Based on the experience of these technologies, further research was carried out and attaches longer chain cationic groups that have anti-bacterial properties. This technique has also been claimed by at least one company in their products. However, the application of these and other anti-bacterial products is invariably after dyeing, mainly by padding methods, with the use of resins. In this work we apply novel reactive long chain cationic products to cellulosic fibres by exhaustion method before dyeing, and promote the chemical reaction with the hydroxyl groups on the fibre. The main objective was to prove that the process is viable when applied before dyeing, and that it has benefits since no salt is used, or used in fewer quantities, and there is no subsequent fixation of the anti-bacterial product by resins, eventually containing formaldehyde is necessary, making it globally into a much more ecological process. EXPERIMENTAL
Chemical reaction with fibre Cotton fabrics (1 5g) were modified using isothermic exhaustion process (75°C).The bath was prepared with 15% (owf) of cationic antibacterialproduct (monocationicsalt) lS2 and epichlorohydrin (molar ratio 1:1) and 20 gL-'of sodium hydroxide. The liquor ratio was 1:20. 0 Woodhead Publishing Limited, 2010 117
Testing methods Determination of antibacterial activity of the materials samples was evaluated according AATCC test method 147 and AATCC test method 100. Washing tests were carried out as described by IS0 105 B01 and IS0 105C06 modified.
Dyeing processes All of the dyeing was carried out in a Ahiba Turbo Color at a 1:30 liquor ratio with 1% direct dye, C.I direct 225, on weight of fabric for 60 minutes. The dyeing was monitored on a system with on-line monitoring and automatic calculation of the exhaustion. On the modified sample, if cationised by the presence of antibacterial quaternary compound, no electrolyte was necessary nor used to exhaust the bath. For cellulosic fabric samples the electrolyte (2OgL-') was added in the dyeing beginning. Dyed fabrics were washed and air-dried at room temperature.
RESULTS AND DISCUSSION This study reports the application of an antibacterial cationic compound to cellulosic fabrics. The presence of antibacterial affects the fabric charge of cotton fabrics and enhances the absorption of anionic dye molecules when compared with the untreated cotton fabrics. The determination of antibacterial mesence in fibre was carried out by evaluation of C.1 direct dye 225 up take (exhaustion). ao 1 70
cotton w UI ZOQL saR
60
+standard
50
-m-nudWd cotton by exhauston m a d
z40
standard sanple w bout sat
W
30 -x-
20
modSbd sanple by irpregnatbn msthcd
10
0 0
10
20
30
40
50
60
Time (min)
Figure 1. Effect of cationization in the exhaustion profile Figure 1 shows the effect on the exhaustion of dye for antibacterial cationic cotton (modified sample) and standard cotton. Conventional dyeing method (with 2OgL-1 of electrolyte) was monitored so as to compare the results with those of modified samples. A sample of modified cotton by a padding method was also evaluated for comparison. Similar exhaustion gradients were achieved using antibacterial cotton and standard cotton but in presence of salt, without an initial dye strike, showing that the exhaustion gradient of the modified cotton can be controlled so as to obtain a uniform dyeing. No 118 0 Woodhead Publishing Limited, 201 0
significant difference in the exhaustion profile was observed between the exhaustion and the padding application of the antibacterialproduct. Since the objective of this work was the evaluation of the exhaustion process, for the exhaustion process different concentrations of antibacterial product were applied and their impact in dye uptake evaluated. Figure 2 compares the exhaustion of dye for cotton treated with 15% (w.0.f) and 7.5% (0.w.f.). As expected the exhaustion of dye reflects the quantity of cationic antibacterial compound in fibre, being about 20% lower when using half the amount. If the lower concentration of antibacterial is sufficient for the objective, then for higher exhaustion some salt should be used.
cotton w im 15%w of mnowtbnlc salt
+modlfled
cotton w ith 7,5%w of mmcatanic salt
-died
I
0
10
20
30
40
50
60
Time (min)
Figue 2- Exhaustion ('YO) versus time for different concentration of antibacterial compound in fibre. The antibacterial product was evaluated measuring the antibacterial activity according AATCC test method 147, before and after washing processes (Table 1). Stuphylococcus aureus- and Klebsiellapneumoniae species of bacteria were tested, and it can be seen fiom the Table that modified cotton before dyeing shows antibacterial activity against Gram +ve and Gram -ve bacteria. Higher activity was verified against Gram +ve bacteria, maybe due to the complexity of membrane of Gram -ve microorganisms. However, for the cotton modified after dyeing there was no antibacterial activity detected. This could be interpreted as confiring that the product reacts with the fibre, and when most accessible reaction sites are already occupied by the dye, there is a lot less probability of covalent fixation of the product on the fibre. The changes of antibacterial activity after dyeing and laundering treatments were analysed. The fabric samples have still retained antibacterial qualities after three washing cycles.
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.Table 1. The antibacterial activity of the modified samples after dyeing and after three cycles washing, according AATCC test methodl 47
ccMI335
CCMIMb
W m (mm)
W m (mm)
Activfty
0
0
negative
Modified cotton after dyeing 0 Modified cotton before dyeing 5.3
0
negative
0.45
positive
Modified and dyed cotton 0.95 after three cycles washing
0.30
Positive
sample Unmod5ed cotton
’ Gram + Staohvlococcu6 aumus:
’Gram
-
Klebsielia Dneumonlae: CCMI- Cuituro Colbdion d industrial
Micmorganism
The shake flask test method (AATCC test method 100) also revealed that the modified fabrics possess antibacterialproperties (Table 2). Table 2. Antibacterialactivity determined according to AATCC 100 test method of the
GM-DBO modified cotton cellulose after washing. Sample Unmodified cotton Modified cotton
Staphylococcus aureus Reduction (%) 0 99.1
Mebsiella pneumoniae Reduction (%) 0 96.2
CONCLUSIONS The described application of antibacterial product was not effective when applied after dyeing, which eliminates this possibility. It was, however, effective in terms of fixation of antibacterial agent to cotton material when applied before dyeing, showing antibacterial effect even after dyeing and standard washing. The subsequent exhaustion dyeing proceeded without an initial dye “strike” indicates that it will dye uniformly When scaling-up. The cationic antibacterial product when applied before dyeing also allows us to develop antibacterial dyed fabrics using less salt in the dyeing process, with clearly advantages in terms of environmental impact. The exhaustion application of the antibacterial product proved as efficient as the padding process. This would be another improvement in energy and time savings, since it doesn’t need the intermediate drying that is necessary when applying the padding process. 120 0 Woodhead Publishing Limited, 201 0
1 G M B Soares, R Vieira, I Cardoso, J Santos, J I N R Gomes, A Langa, P Pereka, ‘Studies of durability and effect on material properties of Merent anti-bacterial products’, proceedings of ATC’04 - 31st Aachen Textile Conference,November 24-25, 2004.
2 R Vieira, G M B Soares, J I N R Gomes, ‘The fixation of anti-bacterial products onto cellulosic fibers’,AATCC conference, Atlanta, USA, 3 1 October-2 November 2006.
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PRELIMlINARY STUDIES INTO WASH-FAST ANTIMICROBIAL TREATMENTS OF POLYESTER 0.Hauck, N. Allen, G.C. Lees, H. Rowe & J. Verran Manchester MetropolitanUniversity, Hollings Faculty, Manchester, UK
ABSTRACT Wash-fatness of antimicrobialtextiles is a key criterion in terms of performance,longevity and of course marketability. The antimicrobial agent must be sufliciently bound to the textile to resist rapid wash-out, yet must also be able to perform its h c t i o n under appropriate conditions of use. These mditions are often moist, for example as a result of perspiration. It is not only the effectiveness and washhtness of the agent which is of concern The application procedure may be required during the finishing stages of manufacture; it would be desirable for the agent to be ceapplied during the dyeing procedure. Any change in the handle of the treated textile must be acceptable. Furthermore,benchscale research may not reflect some of the technical aspects encountered during scale up. The Biocide Poduct Directive may also impact on selection of biocide. The aim of this project is to use a range of approaches which may enhance the wash fastness of antimicrobial treatments of polyesters. Perhaps a unique aspect is the embedded interdisciplinary approach, where chemists, polymer technologists, textile scientists and microbiologists are working together: the chemistry and microbiology approaches are carried out by one individual who will hence acquire a unique and enviable range of skills. Approaches to be taken include: entrapment of the biocide within surface coatings using water soluble polymers and polymerisation reactions; graftins reactions using crosslinking agents in order to introduce new binding sites to the surface of the fibres; explorationofthe use of solvents to modify the surface structure of the polyester in order to improve adhesion of the biocide to the fibres; sol-gel coatings. Preliminary screens will be used as proof of principle. For approaches showing potential, a range of variables will be explored to enable specification of optimum performance. Funding through EPSRC-CASE award with British Sanitized, via Technitex Faraday. INTRODUCTION
Textile surfaces provide an ideal environment for the settling and growth of micm organisms. These microbes thrive on debris trapped between the fibres of clothing causing staining and odour formation. Treatment of fabrics w ith antimicrobialagents, or biocides, is one way of preventing this biofouling of textiles and presents a wide range ofend uses from towels and sportswear,to preventing contaminationof medical fabrics. The wash-fastness of these hygienic finishes is a key criterion in terms of performance, longevity and of course marketability. A series of preliminary applications havebeen made in order to identify a suitable method and application procedure for further investigation.
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There is considerable commercial interest in the successll development of a cost effective post-productiontreatment that exhibits a durable antimicrobial effect. The aim of the project is to improve the washfastness of antimicrobial finishes applied to polyester using a chemical or physical bonding system. The application must be made during the finishing stages of the textile manufacture using standard textile processing equipment. It would be desirable for the antimicrobial finish to be ceapplied during the dyeing procedure. Any change in the handle of the treated textile must be acceptable.
BACKGROUND The demand for antimicrobial fabrics has increasxl significantly in recent years due to increased public awareness of the spread of diseases. The potential European market for biocidal textiles was an estimated 28,000 tons in 2003, which equates to 180 million d of fabric."] Existing treatments have good levels of wash-fastness on cotton but are less durable on polyester garments. Some synthetic fibres can be manufkctured with antimicrobial agents mixed into the polymer before it is spun into fibres!" Such materials have a durable antimicrobial effed but are not suitable for all end uses and applications. Two biocides that have been used for antimicrobial finishing are Triclosan and SiQuat. (Fig. 1). Triclosan is a well established antimicrobial agent that is used in many household products like toothpaste and soaps.
Fig 1. (a) Structure of Triclosan molecule. (b) Structureof SiQuat molecule.
METaODOLOGY Application methods The applications must be made using standard textile processes such as padding or exhaust. The padding method involves dipping fabric through the treatment solution and passing it Uvough rollers. The required level of coating is achieved by adjusting the pressure applied by the rollers to remove unwanted liquor. The exhaust process involves sealing the fabric in individual steel beakers of treatment solution and heating them in a rotating beaker dyer at 120°C. The samples are then dried in an oven called a stenter at 120°C for 2 minutes.
Textile treatments Approaches taken include entrapment of the biocide within surface coatings using polycondensationreactions, water- soluble polymers and sol-gel coatings. The use of crossl i i g agents in thermal grafting reactions has been investigated in an effort to introduce new binding sites to the surface of the fibres.
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Microbiological testing methods SN 195 920 ‘agard i m i o n test’ The agar diffusion test is used to qualitatively assess the efficacy of textiles treated with diffusible biocides. Samples are placed in the centre of nutrient agar plates which have been inoculated with the test bacteria. The samples are incubated at 37°C for 1824 hours. The evaluation of this test is based on the level of growth both under and around the sample. (Fig. 2) The ‘zone of inhibition’ around the test material is measured and any growth present underneaththe sample is scored. JIS L 1902:2002 ‘quantitativetestfor non-leaching actives’ This method is used to determine the antibacterialeffectiveness of textiles treated with non
diffusing active substances. The test material is sterilised and inoculated with a standard number of bacteria The samples are incubated at 37°C for 18 hours. The difference in number of colony forming units (cfu) between 0 and 18 hrs contact with the sample indicates the efficacy of the test material.
(a)
(b)
Fig 2. Example of untreatedtextile (a) showing no efI& on bacterialgrowth, and treated textile @) showing a ‘zone of inhibition’ around the sample.
Samples are subjected to defined wash cycles and retested to establish the level of antimicrobial activity remaining. High Performance Liquid Chromatography (HPLC) is used to determine levels of Triclosan before and after washing.
RESULTS Initial investigations show that all the methods have been successful in applying the biocides to the fabric and results of the washfastness tests pending The exhaust method is achieving lower levels of triclosan than expected and so further work will focus on padding applications.
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Surface analysis The polyester material has been analysed using 3DLaser profilometry. The laser profilometer measures the texture, form and topography profile of the fabric, creating 3D images of the fabric surface. (Fig. 3) This technique can be used to compare the surfaces of treated textiles and visualise the effect that the finishes have on the surface profile of the polyester. FUTURE WORK Samples coated with sol-gel derived titanium dioxide are currently being produced. Titanium dioxide photocatalysts have been widely investigated in the killing and growth inhibition of microorganism^.^^^ 41 The new analytical microscope at MMU will assist in the characterisation of the treated textiles and provide information about the composition and topography of surface coatings applied to the woven samples. Equipment is available in the Department of Clothing Design & Technology at MMU for testing textile properties such as drape, colour-fastnessand breathability. This will allow the assessment of the effect of the finishing treatments on the handle and perlirmance of the fabric. The applicability of the developed finish onto other types of fabric and the possibility of any interactions with other treatments and dyeing procedures will also be exploted.
Fig 3. (a) Image scanned fiom 2 nun’ area of fabric. @) Height profile across cursor fiom ceatre of image (a). (c) Data from image (a) plotted as a 3D image.
REFERENCES 1 U Girrbach, International Textile Bulletin, 2003 2 34-35.
2 I Dring, Anti-microbial, Rotproofing and Hygiene Finishes, Textile Finishing, ed. D. Heywood, Bradford, Society of Dyers and Colourists, 2003. 3 G Fu, P S Vary, and Chhiu-Tsu Lin, ‘Anatase Ti02 Nanocomposites for Antimicrobial Coatings’, J. Phys. Chem. B, 2005 109 8889-8898.
4 W A Daoud and J H Xin, ‘Low temperature Sol-Gel Processed Photocatalytic Titania Coating’, J. Sol-Gel Sci. Tech., 2004 29 25-29.
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ENZYME-CATALYSED COUPLING OF FUNCTIONAL ANTIOXIDANTS ONTO PROTEIN FIBRES
s. JUS'~,G. M. GUEBITZ', v. KOKOL~ 'Technical University of Graz, Institute of Environmental Biotechnology, Petersgasse 12, A-8010 Graz, Austria, e-Mails:
[email protected],
[email protected], 'University of Maribor, Faculty of mechanical Engineering, Textile Department, Smetanova ulica 17, SI-2000 Maribor, Slovenia, e-Mail:
[email protected] ABSTRACT The tke of oxidative enzymes for wool fibre hctionalisation enables the introduction of a number of novel properties. Tyrosinase is able to oxidize tyrosine residues in proteins to quinones, which can further react with free sulfhydryl (thiol), amino or phenolic groups of different substrates. This characteristic is exploited to couple different phenolic antioxidants to the tyrosine residues of wool fibres. The efficiency of tyrosinase was elucidated by comparing the specificity of enzymatic coupling using polyphenolic substrates. The reaction was followed by different analytical methods, namely oxygen consumption, and FT-IR, and UVNIS spectroscopy. The functionalised wool fibres showed increased antioxidant activity using cafYeic acid and chlorogenic acid as substrates.
Keywords: wool fibres, tyrosinase, calYeic acid, chlorogenicacid, grafting. INTRODUCTION Ultraviolet radiation (UVR) - induced skin damage includes acute reactions such as erythema and edema, as well as premature skin aging and carcinogenesis largely determined by chronic exposure. The important role of reactive oxygen species in UVinduced skin damage is well documented. Reactive oxygen species cause injury by reacting with bio-molecules such as lipids, proteins, and nucleic acids, as well as depleting the human skin. Antioxidantsmay intervene at different levels in the oxidative process (e.g. by scavenging of free radicals and lipid peroxyl radicals, removing oxidativelydamaged bio-molecules) [l] [2]. Antioxidants are used to preserve food and other biomaterials by retarding rancidity, discoloration or deterioration due to autoxidation [3]. Chlorogenic acid (CHG) and d e i c acid (CA) are two of the most interesting non-flavonoid catecholic compounds, which are present in many plants and possess anti-inflammatory, antimutagenic, and anticarcinogenicproperties [4]. Tyrosinase catalyses the oxidation by oxygen of a large variety of mono and polyphenols as well as many phenolic derivates such as adrenalin, tyrosine and others. In the presence of catechol, benzoquinone is formed [4]. Tyrosinase is capable of oxidising tyrosine residues in proteins to the corresponding quinones, which can further react with e.g. free sulfhydryl (thiol) andor amino groups resulting in formation of tyrosine-cysteine and tyrosine- lysine cross-links. Quinones have also been suggested to form tyrosine-tyrosine linkages by coupling together. It is believed that tyrosinasecatalysed oxidation of tyrosyl or dihydroxyphenylalanhe (DOPA) residues initiates cross-linking and gelation of adhesive proteins. Since quinones can undergo reactions with various moieties (e.g., tyrosyl residues and amino groups) and Werent linkages 126 0 Woodhead Publishing Limited, 201 0
can be formed (e.g., SchifFbase and Michael's- type adduct), the c h e m i m of quinone-
tanning has not yet been fully established [5]. A.
+
\N-CH,-W(lysll)
Rl-CH,-S R
R
B.
[+I2HO
R
Mkhaelb,addbn reactlon site
OH
Phenol mupiing
Figure 1: Possible non-enzymatic reactions of quinones formed from a tyrosine or tyrosine residue by tyrosinase [5].
In the present work, tyrosinase has been used to graft antioxidant phenolic substrates like d e i c acid and chlorogenic acid onto wool protein substrate. The efficiency of phenolic substrate enzymatic grafting and the antioxidant properties of functionalised wool fibres are assessed.
MATERIALS AND METHODS Wool preparation Merino wool top was cleaned by sohxlet extraction using dichloromethane to remove fatty matters and repeated washing with cold water. The wool was air dried at about 40OC. The wool proteins were extracted overnight from wool by an extensive treatment with 8M Tridurea buffer containing (50 mM) dithiothreitol as reduction chemical at pH 9.3 and 25 "C. The reaction was stopped using 20% iodoacetamide. The wool proteins were dialysed against distilled water for 4 days. The protein content of the enzymes and the wool hydrolysate were determined using the Lowry assay [6].
Enzymatic wool treatment Mushroom tyrosinase was obtained from Sigma Chemical Co. Tyrosinase enzyme treatments were carried out on dried wool top in 0.1 M potassium phosphate buffer (PH 6.5) at 25 "C for 24 hours using 0.5 g of wool fibres and wool to buffer ratio of 1:lOO in a glass flask. The ascorbic acid solution was added as a reducing agent to support conversion of tyrosine to DOPA. The M e i c acid and chlorogenic acid were prepared as a stock solution in dimethylsulfoxide (DMSO) (Fluka); and t h i s solution was further diluted with buffer 50 times to obtain the f d concentration of 5 mg/mL. Tyrosinase dosage was 1000 nkat/g. To deactivate the enzyme the temperature was increased to 85 OC and maintained at this value for 10 min. After the enzyme treatment, fibres were rinsed in distilled water and 1 % acetic acid solution and airdried. The activity of the tyrosinase was assayed according to Duckworth [7'j using L-tyrosine (Sigma) and Ldihydroxyphenylalanine(LDOPA, Sigma) as substrates. 0 Woodhead Publishing Limited, 201 0 127
Determhation of tyroshse activity on wool fibres by mersuring oxygen consumption The activity of tyrosinase against wool fibres was measured by determining the consumption of dissolved 02 during the enzymatic reaction, according to Niku-Paavola er al(1997). 1 g of wool fibres was agitated in 100 mL. of 0.1 M buffer at pH 6.5 and 25 "C for 24 hours in a flask, using a tyrosinase dosage of 1000 &t/g of wool. The buffer medium was bubbled with pure oxygen for 10 min before the enzyme solution was added. Control treatments were carried out similarly and for the comparison a measurement on standard L-tyrosine solution was made. The oxygen consumption was measured using the OXlLAB V5 apparatus 0.
Quantification of DOPA during treatment of wool proteins (Wp) by tyrosinase The enzyme/substrate (tyrosinaselwool hydrolysate) mixture (20 pL) was diluted with 980 pL of distilled water, 70 pL of ethylenediamine, and 50 pL of 2M ethylenediamine &hydrochloride (pH 11). The mixture was incubated at 50°C for 2 h in the dark, and then the fluorescence intensity was measured using a W N I S spectrofluorometer (Tecan). The excitation and emission wavelengths were at 420 and 543 nm, respectively. The concentrations of the DOPA residue in the preparations were estimated using a standard fluorescence curve of DOPA [8]. For the Dopa Quinone @Q) quantification MBTH (3-methyl-2-benzothialinone hydrazone hydrochloride monohydrate) was used. MBTH reacts with DQ to form a pink pigment with Amax at 505 nm. The assay solution was prepared by mixing 480 pL of the enzyme/substrate reaction mixture, 980 pL of 4.3% (v/v) DMF (dimethyl formamide) in distilled water, and 580 pL of 20.7 mM MJ3TH. The total volume was 2 mL. The reaction mixture was incubated at 25OC for 10 min before the absorbance measurement (at 505 nm)[8].
ATR-FlrIR and NIR FT Raman anaIy8is
IR spectroscopic analysis was used to iden* the surface modification of the wool fibres, using a Perkin - Elmer Fourier Transform infkred (FT-IR) spectrophotometer with Golden Gate attenuated total reflection (ATR) attachment. The Raman spectra were measured on the same spectrophotometer equipment with a FT-Raman module with Nd:YAG laser source. Spectra were accumulated h m 64 scans at a resolution of 4 cm-'. An optical bench alignment was performed before each Raman measurement to ensure that the spectrometerwas fine-tuned and the detector signal maximised. Antioxidant activity determination The antioxidant activity of phenols used and standards was determined according to the ferric thiocyanate method with minor modifications. Each sample of treated wool (200 mg) was mixed with 2 mL distilled water and 5 mL linoleic acid emulsion (0.02 M, pH 7.0) and 5 mL phosphate buffer (0.2 M, pH 7.0). Linoleic acid emulsion was prepared by mixing 0.5608 g of linoleic acid with 0.5608 g of Tween 20 as emulsifier, and 100 mL phosphate buffer (0.2 M, pH 7.0), and then the mixture was homogenised. The reaction mixture was incubated at 37OC. Aliquots of 0.1 mL were taken at different intervals during incubation. The degree of oxidation was measured by sequentially adding 4.7 mL ethanol (75%), 0.1 mL ammonium thiocyanate (30 %), 0.1 mL. sample solution and 0.1 mL. ferrous chloride (0.02 mg, in 3.5% HC1). The mixture was 128 0 Woodhead Publishing Limited, 2010
incubated for 3 min and then the peroxide value was determined at 500 nm [9]. During the linoleic acid oxidation, peroxides are formed and leading to oxidation of Fez' to Fe3'. The procedure was repeated every 3 h and later in 24 h intervals until the control reached its maximum absorbance value. High absorbance indicates high linoleic acid emulsion oxidation. The solutions without a treated sample were used as a control [lo]. All data on total antioxidant activity are the average of triplicate experiments. The inhibition percentage of lipid peroxidation in linoleic acid emulsion was calculated by the following equation: I inhibitionoflipidperoxidation(%) = [(I -~sampld/Acontrol)l 100 where Amnwol is the absorbance of control reaction and Asampleis the absorbance in the presence of caffeic acid, chlorogenic acid or standard compounds [9;10].
RESULTS AND DISCUSSION The objective of this work was to analyse the effectiveness of enzymatic coupling of two antioxidants, caffeic acid and chlorogenic acid, on a wool protein fibre. The crosslinking contributes unique properties to both the structure and the function of the wool protein and consequently changes the fibre properties. The activity of tyrosinase on wool fibres was measured as consumption of the cosubstrate 0 2 . The initial 0 2 concentration was about 30 mg/L (enriched by pure oxygen); the results are presented in Figure 2. In the first line we noticed an obvious difference between the wool sample treated in buffer with tyrosinase and the wool sample treated in buffer mixture from EDTA and ascorbic acid. After 15 min of incubation a small amount of oxygen consumption was measured and it was reduced continuously during the incubation period of 24 h. In the case of the wool sample treated with EDTA and ascorbic acid it fell down to 5 mg/L 0 2 . The difference and the increased action of the enzyme tyrosinase on wool substrate in a buffer media and the buffer-ascorbic acid media could be the consequence of the isoelectic range of the wool protein fibre (PH 4-6). In the case of the small substrates like d e i c acid it was observed that the oxygen concentration in the treatment medium decreased and reached the minimum of 1.2 mg/L during the first 30 min of enzyme treatment. In the case of chlorogenic acid the enzyme oxidised the substrate at a slower rate. The possible reason could be the sterical hindrance of the chlorogenic acid and also in the substrate inhibition of the enzyme during the enzymatic treatment. Complete oxidation of 1 mol of tyrosine to dopaquinone consumes 1.5 mol of 02. Used wool contains about 14 -01 tyrosine residues / 1 g of fibres that are probably cuticle-bound and to some extent accessible to the enzymatic reaction. Limited accessibility of tyrosine residues for tyrosinase is an apparent reason for the slow 0 2 consumption. The surface of untreated wool fibre is heavily cross-linked by disulphide bridges, thus hindering penetration of enzymes into the fibre [5]. Because of the small size of the chosen substrates the possibility of enzyme and substrate diffision into the wool fibre also exists.
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-
Tyrosine
-A-
WWadd
tCHG
\
Figure 2: Oxygen consumption during the enzyme treatment of different substrates (Wo- wool fibres, Wo-asc. acid - wool fibres with ascorbic acid supplement, CAcafTeic acid (5 mg/mL) and CHG - chlorogenic acid (5 mg/mL). Tyrosinase oxidises the tyrosine residues on the wool substrate to yield L-pdihydroxyphenyl-a-alanine (DOPA) residues, followed by converting the DOPA residues to Dopa quhone (DQ) residues. The DOPA and DQ are significantly responsible for both the intermolecular cross-linking and the interfacial adsorption properties of the proteins. For the quantificationof DOPA, we employed the fluorescent technique which was originally reported by Yagi and Nagatsu (1960) and then optimised it for the analysis on a DOPA-containing protein [8]. The quantification results are presented in Figures 3 and 4. When pure tyrosine (Tyr)was used as substrate, the conversion of Tyr to DOPA increases firom 0 to 0.008 mg/mL within 1 hour, but gradually decreased afterwards depending on the incubation time. In the case Wh (wool hydrolysate) a small increase of conversion potential fiom Tyr to DOPA occurred and reached the maximum after 3 hours of incubation. The difference is a consequence of the substrate structure and the accessibility of the wool tyrosine residues to the enzyme. The use of smaller substrates which are chemically similar to DOPA results in a strong decrease of DOPA conversion during the jirst 2 hours in the case of Wh and caffeic acid. Similarly, the conversion optimum is reached after 4 hours of incubation in the case of Wh and chlorogenic acid combination. The decrease of DOPA after longer incubation time is the consequence of the further oxidation of DOPA to DQ (Figure 3).
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Figure 3: Conversion volume of tyrosine residues in different substrates (Tyr- tyrosine, Wh - wool hydrolysate, CA- caffeic acid, CHG - chlorogenic acid) to DOPA depending on the incubation time. The conversion profile of DOPA to DQ is shown in Figure 4. In the case of Wh substrate and combination with CA and CHG the conversion increased during the first 2 hours of enzyme treatment and reached the maximum after 5 hours of incubation, using Wh and CHG as substrate. After 5 hours of incubation, the conversion slightly decreased in all cases. The reason for this occurrence could be found in the supplementary auto-oxidation of DOPA to DQ, which could occur also without the enzyme catalysis. Thus, the conversion of DOPA to DQ involves enzymatic and nonenzymatic mechanisms [8].
95 94 -
q3 92 -
41 0,
Figure 4: Conversion of DOPA into DQ during the enzyme incubation with different substrates (Tyr- tyrosine, Wh - wool hydrolysate, CA- caffeic acid, CHG - chlorogenic acid) depending on the incubation time. From the point of view of structural changes it is significant to analyse the FT-IR spectra (Figure 5) in the followhg ranges: 3500 - 3000; 1700 - 1450; 1100 - 950 cm-' and 3100 - 2700 cm-'. A substantial increase in absorbance was observed at 1630 cm-' which can be attributed to the amide I or aromatic residues present in the soluble 0 Woodhead Publishing Limited, 2010 131
substrates. When the wool fibre was incubated with caffeic acid or chlorogenic acid and tyrosinase, the absorption bands at 1630, 1515, 1450, 1390 cm-' became weaker. The decrease in the peak at 1450 cm-' may indicate a loss of -NH3+ groups and is consistent with a covalent reaction between the enzyme oxidation of chlorogenic and caffeic acid and the further reaction with the amino group of the wool fibre proteins. The results are shown in figure 5. 9co 41
416 4u
w 416
abr ap
918
914 412 910
am 9Q
qm Qm, an0
m
nm
am
ym
lKn
ZlOD
leo
l a
ldm
lom
K n b d 4 0
-1
Figure 5: FT-IR spectra of buffer treated wool fibre (A-control), wool fibre treated with tyrosinase enzyme and chlorogenic acid (B) and wool fibre treated with tyrosinase enzyme and caffeic acid (C).
Figure 6: Raman spectra of buffer treated wool (A-control), tyrosinase treated wool with chlorogenic acid (B) and tyrosinase treated wool with caffeic acid (C). 132 0 Woodhead Publishing Limited, 2010
When wool fibres were incQbated with tyrosinase and the soluble substrates CA and CHG a considerable increase of peak intensity (Figure 6) was observed at 3305 cm-' which can be attributed to the amide A and amide B bands. An interesting region in the Raman spectra presents in the range 3100 - 2700 cm-'. This band region is characteristic for dipolar ions of the amino acids RCH(NH33COO-.The reason of increasing intensity of this region in the case of spectra B and C could be a result of euzyme treatment and also the possible enzyme residue on the fibre. The intensity of the peak in the case of spectra B and C at 1450 cm-' based on the C-H bond is increasing, which can be the result of enzymatic coupling reaction and the permanent remnant of the soluble substrates on the fibre. The broad envelo e between 1550 and 1700 cm-' corresponds to amide I vibration. The band at 1690 cm- IS assigned to carbonyl groups of the asparatic and glutamatic acid residues, and the band centred at 1650 cm-' is typical of the ahelical amide I. Bands at 1615, 1604, 1585 and 1550 cm-' are assigned to various ring vibrations of the aromatic amino acids like tyrosine and tryptophan. The peak at 1615 cm-' shows a slight increase, as the possible consequence of phenolic coupling reaction of soluble substrates on the tyrosine residues or the coupling of phenolic groups on the primary amino groups of the insoluble wool protein substrate. The intensity of these peaks is reduced in the case of enzymatic treatment of catTeic acid after extreme washing (30°C, 2 h) (data not shown). The amide IV band at 640 cm-' has become more intense. The antioxidant activity of the caffeic and chlorogenic acids was evaluated by in viho testing using the ferric thiocyanate method. The method measures the amount of peroxide produced during the initial stages of oxidation, (peroxide is the primary product of oxidation [9].) Total antioxidant activity of acids and standard compounds was determined in the linoleic acid system. For the determination of the durability and the effectiveness of enzymatic coupled substrates on the wool fibres, the wool was thoroughly washed under extreme conditions (2 h, 30°C). The results of activity assays of the samples before (CA and CHG) and after washing (WCA and WCHG), after 48 h incubation with linoleic acid emulsion are summarised as inhibition (%) data and presented in table 1.
P.
Table 1: Antioxidant activity (AA) of the enzyme treated samples before (CA and CHG) and after washing procedures (WCA and WCHG) Samples % Inhibition AA Mean abs. at 500 run (48 h) Control I 1.1136*0.291 CA 75.12 0.2770 f 0.041 WCA 45.5 0.6060 f 0.009 CHG 54.15 0.5 105 f 0.047 WCHG 33.04 0.7456 f 0.020
In general, the oxidation of linoleic acid was inhibited by the enzyme coupled antioxidant substrates even after a strong washing treatment (WCA and WCHG) in comparison with the control sample. The caffeic acid (CA) and chlorogenic acid (CHG) treated wool samples exhibited potent antioxidant activities with 75.12 % and 54.15 % inhibition of linoleic acid peroxidation, respectively.
CONCLUSIONS In the present work, tyrosinase has been used to graft the antioxidant phenolic substrates like caffeic acid and chlorogenic acid onto wool protein substrate. The incorporation of 0 Woodhead Publishing Limited, 201 0 133
phenolic substrates onto wools fibre increases the antioxidant activity and yields a modified textile fibre with new properties and characteristics.The oxygen consumption shows that the insoluble wool is the substrate for the tyrosinase. The ATR-IR and NIR Raman spectra, specifically the amide I, I1 and 111 regions, confirmed the functionalisationof the wool surface. It was ascertained that a higher antioxidant activity (75.12 %) was obtained by caffeic acid than by the chlorogenic acid (54.15 %) and that this effect doesn't decrease after a strong washing procedure.
Acknowledgements
This research project has been supported by a Marie Curie Transfer of Knowledge Fellowship of the EC's 6 FP (MTKD-CT-2005-029540, POLYSURF).
REFERENCES 1 M Y Moridani, H Scobie, A Jamshidzadeh, P Salehi and P J O'Brien, 'CaEeic acid, chlorogenic acid, and dihydrocaffeic acid metabolism: Glutathione conjugate formation', Drug Metabolism and Disposition, 2001 29 1432-1439. 2 S R Georgetti, R Casagrande, V M Di Mambro, A E C S Azzolini and M J V Fonseca, 'Evaluation of the antioxidant activity of merent flavonoids by the chemiluminescence method', Aaps Pharmsci, 2003 5.
3 S C Huang, G C Yen, L W Chang, W J Yen and P D Duh, 'Identification of an antioxidant, ethyl protocatechuate, in peanut seed testa', JAgric Food Chem, 2003 51, 2380-2383. 4 J W Sizer, 'The action of tyrosinase on proteins', J of Biolog Chem, 1946 163 145-
157.
5 R Lantto, E Heine, G Freddi, A Lappalainen, A Miettinen-Oinonen, M L NikuPaavola and J Buchert, 'Enzymatic modification of wool with tyrosinase and peroxidase', J Text Inst, 2005 96 109-116. 6 0 H Lowry, N J Rosebrough, A L Farr and R J Randall, ' Protein measurement with the folin phenol reagent', J of Biolog Chem, 1951 193 265-275. 7 H W Duckwort, J E Coleman, Thysicochemical and kinetic properties of mushroom tyrosinase', JofBiolog Chem, 1970 245 1613. 8 Y Kuboe, H Tonegawa, K Ohkawa & H Yamamoto, 'Quinone cross-linked polysaccharidehybrid fiber', Biomacromolecules,2004 5 348-357. 9 I Gulch, 'Antioxidant activity of caffeic acid (3,4-dihydroxycinnamic acid)', Toxicology, 2006 217 213-220. 10 F Odabasoglu, A Aslan, A Cakir, H Suleyman, Y Karagoz, M Halici and Y Bayir, 'Comparison of antioxidant activity and phenolic content of three lichen species', Phytotherapy Research, 2004 18 938-941. 134 0 Woodhead Publishing Limited, 2010
PART I1
HEALTHCARE AND HYGIENE PRODUCTS
HEALTHCARE AND HYGIENE PRODUCT& AN OVERVIEW SCAnandMBE Institute for Materials Research and Innovation,University of Bolton, Bolton, UK
INTRODUCTION A similar overview was published by the author in 2006, in which a number of crucial issues regarding medical products in general and healthcare and hygiene products in particular were identified and debated amongst clinicians, environmentalists, drug companies etc (1). This overview presents an update of the issues discussed in the above paper and it is recommended that both overviews should be studied together.
Disposable products The medical nonwovens market now has an annual value of more than €1.4 billion, according to leading manufacturer Ahlstrom. In tonnage terms, with an overall production of around 100,000 tonnes, 42% of materials supplied go into drapes, 29% into gowns, 21% into sterile barrier systems and 8% into facemasks. Facemasks are likely to experience the highest growth in the next few years of 1 1.1 % annually with growth for drapes and gowns around 5.1% and sterilisation wrap 4.1% (2). Regionally, the least growth - around 3% per year in the years up to 2012- is likely to occur in the highly penetrated North American market, where disposable surgical drapes are employed in 90-95% of all major surgical procedures and single-use surgical gowns in 80% of them. Higher growth rates of 5.6% and 7.2% are anticipated for medical nonwovens in Europe and Asia Pacific region respectively over the same period per year, up to 2012. Annual growth for India’s healthcare industry meanwhile, is predicted to grow by over 20% per annum and Ahlstrom will start manufacturing medical nonwovens there early in 2010 (2). The major factors currently favouring the increased employment of single-use products in medical environments include: a) many hospitals are still treating wound infections rather than pro-actively avoiding infections; b) the abuse of antibiotics has created resistance to treatment in hospitals; c) throughout the world new viruses and multi-resistant bacteria (such as MRSA, Swine Flu etc) are becoming increasingly difficult to treat successfully; d) there is a need to reduce/eliminate hospital infections and mortality rates; and e) the aged population is increasing . Ecofriendly products With the demand for ecofi-iendly products from both consumers and manufacturers stronger than ever, biodegradability of disposable medical products has become a hot topic. In 2008, INDA and EDANAjohtly issued flushability guidelines providing a set of tests and conditions for wipes brands to be able to put a flushable label on their packages. Hydraspun technology patented by Ahlstrom and Ecoflex- a fully biodegradable, compostable polyester developed by BASF are just two examples of a number of biodegradableproducts available on the market. 0 Woodhead Publishing Limited, 201 0 137
Such products are normally based on cellulosic fibres such as viscose rayon which are wetlaid using a water soluble bmder, such as polyvinyl alcohol (PVOH),or can also be wetlaid using high-pressure, water jets (hydroentanglement).
Antimicrobial textilea A summary of the various antimicrobial fibres currently available has already been published elsewhere (3). A number of excellent reviews of antimicrobial textiles have been published, which address a large number of issues associated with such fibres and products (43). Qm has explained the mechanism of antimicrobial activity of a number of natural organic and inorganic polymers. He explained the historical and current practices of utilising silver ions, either on its own or in combination with other antimicrobial polymers, such as alginate and chitosan, in order to achieve antimicrobial properties in woundcare and other applications. The sustained release of silver from silver complexes helps in maintaining a constant level of ionic silver in the contact area. The level of ionic silver is controlled by the presence of chloride ions in wound fluid. Chloride ions will react with silver ions to form a silver chloride salt (AgCl(n)) (4). In another review, the authors have given full account of the necessity of antimicrobial treatment of textile materials, mechanism of antimicrobial activity, and a wide range of formulations for application on textile fabrics during dyeing or finishing processes. Chitosan and fluoro polymers were found to be the most suitable finishing agents for medical and healthcare products to act as barriers against microorganismsand blood (5). A number of other reference sources have been highlighted in this overview, which deal with different aspects of antimicrobial activities and potential of different chemicals and agents (6,7 and 8).
RECENT ADVANCES Spunmelt fabries and products It has already been demonstrated earlier in this overview that polymer-based spunlaid and meltblown and their combinations are the fastest growing technologies in global terms. It is also a fact that their use in personal care, hygiene, healthcare and medical applicationsare growing rapidly across the world. Spunmelt technology for the manufacture of singleuse disposable Operating Room (OR) garments is discussed in depth here. In the spunlaid process, the fibres processed are normally between lOpm to 3 0 and~the process involves either area or patterned thermal bonding process to consolidate the filaments. In the meltblown process, the extruded filaments are attenuated by the high-velocity hot air streams to form microfibres. Microfibres with an average fibre diameter of 2 to 7pm are produced, with an average fibre diameter of 2 to 4pm being more typical. These fibres offer high surface area, more uniform surface and small pore size and distribution which give the fabrics good thermal-insulation, filtration efficiency and high barrier properties. It is feasible to combine both spinlaying and meltblowing processes in series in a single process. It will be appreciated that a number of combinations are possible, depending upon the characteristics required in the final product. Different possibilities are: S; SS; SSS; SM; SMM, SMMS; SSMMS; SSM; SSMM; SMS; SSMS; M, MM; etc. The most common combination for operating room garments are SMS and SMMS, although in other set-ups SMMMS combination is also used. 138 0 Woodhead Publishing Limited, 2010
The main advantages of nonwoven spunmelt fkbrics for operating room garments and fabrics are (9): 0 Cross-contamination (AIDS,MRSA, SARS). Conventional textile drapes and gowns will not meet the performance requirements relating to microbial penetration of the latest standards (e.g. EN13795). Single use systems offer maximum safety and sterility (barrier properties of multi-use products degrade with time). Virtuallylinthe. Low cost - ideal for single use. 0 Barrier effect of meltblown layer. Codperformance Control (SMS, SMMS or SMMMS versus S in SARS outbreak). Some of the latest developments in this particular area are (9): Different fibres - W o n t Suprel (polyester/polyethylene). Lamination - Ahlstrom BVB (Breathable Viral Barrier) 3 layer construction, with a monolithic film as the middle layer. Higher Hydrohead - SAAF “Medalon +”. lnherent Antimicrobial - “SAAF Medalon A”. USA consumes 6 times as much spunlaid fabrics into medical products as Europe and 80% of USA market for gownsfdrapes is single use product.
REFERENCES 1 S C h a n d , Healthcare and Hygiene Products: An Overview, Medical Textiles and Biomaterials for Healthcare, Cambridge UK, Woodhead Publishing Ltd, 2006 page 75.
2 Nonwovens Report International, 2009,s page 30. 3 S C Anand, Healthcare and Hygiene Products: An Overview, Medical Textiles and Biomaterials for Healthcare, Cambridge UK, Woodhead Publishing Ltd, 2006, page 77. 4 Y. Qin, ‘Novel Antimicrobial fibres’, Textiles Magazine, 2004 2 16.
5 T Ramachandran, K Rajendrakumar and R Rajendran, ‘Antimicrobial Textiles - an overview’, IE(I) Journal - TX, Feb 2004 84 42. 6 R Singh, A J a b , S Panwar, D Gupta and S K Khara, ‘Antimicrobial activity of some natural dyes’, Dyes and Pigments, 2005 66 99-102.
7 K F El-tahlwy, M A El-bendary, A G Elhendawy and S M Hudson, ‘The antimicrobial activity of cotton fabrics treated with different crosslinking agents and chitosan’, carbohydrate polymers, 2005 60 42 1-430.
8 Y Gao and R Cranston, ‘Recent advances in antimicrobial treatments of textiles’, Textile Research Journal, 78(1) 60-72. 9 S C Anand, ‘Nonwoven textiles: an expanding and exciting market’ Chamber of Commerce Conference, Istanbul, Turkey, May 2005. 0 Woodhead Publishing Limited, 201 0 139
CELLULOSIC MATERIALS FOR ODOR AND pH CONTROL J. K. Dutkiewicz Buckeye Technologies Inc., Memphis, USA ABSTRACT A new technology has been developed to control odor and pH in medical and hygiene care absorbent composites. It employs certain inhibitors of enzymes responsible for generation of malodorous substances. Cellulose fiber and airlaid nonwoven substrates served as particularly convenient carriers for some chemicals which can modify the structure of an enzyme andor block its active site. The concept was effectively used to slow down the fermentation of urea in urine in personal hygiene materials and suppress the emission of ammonia. An additional benefit of the new technology was a control of the pH and maintaining it in a slightly acidic, skirrfriendly range. The approach proved to be effective also in suppressing odors associated with menstrual fluid and sweat.
INTRODUCTION
Malodorous substances are released h m body fluids due to their enzymatic decomposition by ubiquitous microorganisms. Commonly encountered odorants produced in these reactions are certain sulfides, amines, fatty acids and ammonia. The latter is generated fromurine due to the fermentation of urea, a process catalyzed by urease. Ammonia has unpleasant, strong smell and changes the pH of body environment h m slightly acidic to alkaline. This effect can be detrimental to the epidermal and dermal tissue andmay lead to microbial infections. Various methods have been tried to alleviate the odor and address the skin wellness issues. To this effect, producers of personal hygiene articles have used so far technologies based on odor absorbers, fragrances, acid compounds neutralizing ammonia and antimicrobial agents. A new approach described in this paper is based on odor prevention rather than its removal by embedding inhibitors of specific enzymes within the absorbent system of incontinence devices.
EXPERIMENTAL MODEL The key elements of urease's active site are two nickel ions and a molecule of water located inside a structure which creates a "trap" for a molecule of urea. A potent inhibitor can block this site or inactivate it by deforming its geometry. Some of the known compounds which can thus save urea from the enzymatic destruction have been used so far in various areas such as medicine [ 1,2], agriculture and animal farming [3]. The basic component of the experimental system applied to this study was an absorbent material normally used in personal hygiene articles. In principle this would be loose or bonded cellulose fluE, possibly blended with cross-lied sodium polyacrylate granules (Imown as superabsorbent polymer, SAP) for enhanced liquid capacity. Cellulose fibers or whole composites served as carriers of known and potential urease inhibitors. These substances were physically attached to the absorbent core by exhaustion from their solutions and subsequent drying of the substrates. A few examples of materials treated this
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way will be given below to illustrate the concept. Descriptions of the procedures and chemical modifications are contained in the patent application [4]. Practical validity of our approach was evaluated with the aid of a simple ammonia emission test. It was performed in hermetic containen with samples of the studied materials, maintained at constant temperature of 37°C (Fig. 1). The boxes were also equipped with two outlets, one for introducing the test liquid and the other for inserting the ammonia Draeger test tube. After inseaing an absorbent sample with an aliquot of the liquid, the container would be sealed off and the experiment would start immediately. Measurements of the concentration of the generated ammonia were taken during the test at various time intervals for monitoring the kinetics of the decomposition of urea. Thus obtained results could be presented in the graphical form by plotting the amount of ammonia released to the atmosphere inside the containers against the time of the experiment. Examples of such graphs are shown below. The liquid chosen for the experiments was a blend of human urine specimens donated each time by the same group
Figure 1. Ammonia emission test set up of healthy adults. Such natural fluid is initially sterile and relatively stable. It begins to decompose readily only after being contaminated with microbes producing urease. In our experimental model, rather than depend on ureasesecreting microorganisms to trigger the reaction, we chose to add a predetamined amount of the enzyme (U1875, Sigma) directly to the liquid (O.lmV100ml). This enabled us to better control the experimental conditions and ensure that the tests be completedwithin a practical period of time.
AMMONIA EMISSION STUDIES
Each individual series of tests required a fresh blend of liquid specimens which could vary to some extent in their composition depending on the actual donors’ diet and time of acquisition. Therefore, the obtained data could be compared quantitatively only within the Same series of experiments. In our test conditions we could detect ammonia odor directly above the sample containers with the stoppers removed and through a ply of gauze only if the concentration inside the boxes was at least about 15Oppm. This sensation was confiied independently by several panelists of different ages and sexes.
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Investigation of cellulose composites with various inhibitors
A number of known and potential urease inhibitorswere screened as candidates for treating cellulose-based absorbent systems. Acetohydroxamic acid (AHA) was one the examples. This compound is used clinically to dissolve struvite stones [5]. An AHA molecule has a shape which fits very well to the active site of urease,therefore it can compete effectively against urea to form a stable complex with the enzyme. This inhibitor is water-soluble and can be easily applied to a fibeFbased substrate. For this purpose we chose ViZorW 3905,a Buckeye-made airlaid nonwoven. The latter material contained SAP particles, had a basis weight of 250g/m2and a web density of 0.094 g/cm3.
0
1
2
3
4
5
6
Tlmm. hra
Figure 2. Ammonia emission fiom Vizorb@ 3905 impregnated with acetohydroxamic acid and from untreated control Vizorb@ 3905 nonwoven. Each sample (10 g) was insulted with 80 ml urine/urease mixture. The graphs in Fig. 2 show the odor-controlperformance of such composite before and after treatment with AHA. As expected, the nonwoven with acetohydmxamicacid proved itself a powerful ammonia-control system even at a very low add-on level of the inhibitor. According to some reports [6-81, certain metals such as copper, cadmium, zinc and cobalt have an inhibitory effect on urease. The authors of these articles speculated that some polyvalent metals could replace nickel atoms in the mase enzyme and thus render it inactive. Based on this theory we decided to apply several metal salts to our experimental model. We tested only chemicalswhich would be considered safe for medical and personal care uses. Some results are shown in Fig. 3 which illustrates the inhibitory potency of fibrous materials treated with various metal cations. The obtained data suggest that the tested materials were able to retard the emission of N H 3 . It is interesting to note that positive results were obtained with Al and Fe sulfates, which are not commonly cited in the literature as potent urease inhibitors. We postulated that these metals would be effective
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only in the soluble ionic form so that the cations be transported by the liquid to urease macromolecules and reduce their catalytic power. Indeed, as illustrated in Fig. 4 the inhibitory activity of aluminum sulfate is in contrast with total ineffectiveness of insoluble aluminum hydroxide precipitated on cellulosic fibers. Polyvalent metals can form chelates with proteins and thus cause their deformation. We think that this mechanism can be applied as well to the urease macromoleculeand may be yet another factor influencing the lytic activity of the enzyme. 700 8M)
500
h
i" 8300
E
100
0 0
I
3
2
4
6
5
nma, hrn
Figure3. Ammonia generation in Vizorb@3905 impregnated with a)ZnCh, b) Alz(SO4), and c) Fe@04)3. Liquid insult volume: 80 ml urine/urease. Figure 4. Effect of Vizorb@3905 impregnated with Alz(SO4)3 and with Al(0Q on the
+ Al Sulfate ~
-Al Hydmide
A Control
0
0.5
1
1.5
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2.5
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The,h n
emission of ammonia after insulting the samples with 100 ml urine/urease.
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3.5
FRESH COMFORT^ TECHNOLOGY The results of the studies described above became the basis for developing commercial cellulosebased materials and products for controlling the malodors generated h m body fluids and for preventingthe pH of the wet absorbent system from becoming alkaline. This new, proprietary technology was named FreshComfortTM. It can be applied to cellulose fluff and to other individual components of the absorbent system, to whole bonded composites in the form of airlaid nonwoven material%and to finished hygiene products. The main criteria used in the evaluation of various considered chemistries of the developmental model were safety, skin wellness, odorcontrol feature, absorbency and processability. Our preferred technology had to satisfl all the technical requirements and, at the Same time, be cost effective. The optimum variant was tested in numerous executions of individual materials and composites. The graphs in Fig. 5 were created by using data obtained h m many tests with various structural absorbent designs. They technology on ammonia emission in a range of illustrate general impact of FreshComfortTM personalhygiene applications Control of pH Our studies with urease inhibitor-modified composites indicated that the new materials
were able to maintain the slightly acid pH on the surface of the absorbent pad containing urine. Healthy skin has its own pH at a level which is somewhat lower than neutral. This condition ensures the stability of natural oil layer present on the skin and reducesthe risk of microbial infectionsand irritations. 700
600 500
E
1-
2 400
200 100
0 0
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-.
a
6
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hn
Figure 5. General impact of FreshComforP on ammonia emission h m personal hygiene absorbentsbased on cellulose fluff.
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Blends of cellulose fluff and S A P were insulted with ureaseenriched urine and the change of surface pH was measured over a period time. Fig. 6 and 7 show the obtained RSultS.
9.0 8.5
w
I
-
A
:
0.0
x
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5
7.0
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y A
u I
6.5
Fluff/O%S
6.0
Fluff/lWoSAP
5.5
5.0 0
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6
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10
8
12
Tlme (hn)
Figure 6. Surface pH on pads made with regular cellulose fluff.
9.0 8.5
8.0 7.5
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OCF/O%SAP-
rn
OCFIlO%sAP
A
OCFQO%SAP
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OCFIM%SAP
7.0 6.5
x
0
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x
A.
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,: 8
-7.-
X
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Tlme (hm)
Figure 7. Surface pH on pads made with urease inhibitor treated cellulose fluff.
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Control of other odors Airlaid pads made of cellulose fl& were modified with the FreshComforP formulation and tested for their effect on some malodorous substances characteristicof menstrual and sweat fluids. The cellulose fluff used for preparing the samples was Foley FluESB made by Buckeye). In the first series the malodorous canpounds were represented by a mixture of triethylamine, 1100 ppm, and dimethyldisulfide, 980 pprn, which were evaporated h m their solution in propylene glycol (0.05 ml) in a oneliter, sealed vessel. The vessel was conditioned at 26°C while it contained inhibitor-modified or control airlaid samples (1.5 g) made of fluff and binder fiber. A similar test was run later using isovaleric acid (660 ppm) instead of the mixture of the sulfide and the amine. ”he concentrations of the gases were measured in the headspace at the beginning of the experiments and after 2 hrs. Gas samples were collected from the test vessel with a special syringe and analyzed by gas chromatography. It was interesting to find out that both the unmodified airlaid pads and the ones modified with the urease inhibitor were able to eliminate triethylamine from the headspace to undetectable levels. In the same study the amount of dimethyldisulfidein the headspace remained constant over the time of the test at 2,700 ppt for the control md at 1,700 ppt for the experimentalairlaid samples. The data obtained from the similar experiments with isovaleric acid indicated that the samples modified with the mase inhibitor were also more effective than the unmodified material. In this case the concentrationof the odorant in the headspace increased during 10 hrs from 300 ppt to 850 ppt for the control whereas the modified airlaid pads were able to decrease the amount of isovaleric acid in the test vessel initially to 200 ppt and then slow down its accumulationto 450 ppt after 10 hrs.
CONCLUSIONS The aim of this paper was to report the results of our studies on the modification of cellulose and cellulossbased composites with urease inhibitors. The obtained data support our suggestion that the new technology is a simple and effective way of controlling ammonia odor caused by the decomposition of urine. Another seemingly important benefit of this approach is the ability of the modified systems to maintain the pH at a level benign to skin. In addition to that, the evidence based on our lab data suggests that the applied treatment not only retards the emission of ammonia but can also help reduce other odors typically related to menses and sweat. REFERENCES 1 M Houimel, I Corthesy-Theulaz, I Fisch, C Wong,B Corthesy, J-P Mach and R Finnern, ‘Selectionof human single chain Fv antibody fragmentsbinding and inhibiting helicobacter pylori urease’, Tumor Biol, 200 1 22( 1) 36-44. 2 K Phillips, D J Munster, R A AUardyce and P F Bagshaw, ‘Antibacterial action of the urease inhibitor acetohydroxamic acid on helicobacter pylori’, J Clin Pathol, 1993 46(4) 372-373.
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3 M D Swerdloff, J F Kolc, M M Rogic and L L Hendrickson, Phosphoroamide urease inhibitors and wease inhibited urea based fertilizer compositions, US Patent Office, Pat No 4 517 007, May 1985.
4 J K Dutkiewicz, Material for odor control, US Patent Office, Pat Appl No 2006/0029567 Al, February 2006. 5 J A Downey, J C Nickel, L Clapham and R J McLean, ‘In vim inhibition of stmvite
crystal growth by acetohydroxamic acid’, Br J Urol, 1992 70(4) 355-359. 6 G I Pt!rez-PBrez, C B Cower and M J Blaser, ‘Effectsof cations on Helicobacter pylon urease activity, release, and stability’,Znfect Zmmun, I994 62( 1) 299-302.
7 T Matsukura and H Tanaka, ’Applicability of zinc complex of Gcarosine for medical use’, Biokhim, 2000 65(7) 961-968. 8 Z Faixovfi, s. Faix, ‘Influence of metal ions on ruminal enzyme activities’, Actu Vet Brno 2002,71(4) 451455.
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DEVELOPMENT OF A HIGH-ABSORBENT SANITARY NAPKIN A. Das,V. K. Kothari, S. Makhija, Avyaya Department of Textile Technology, Indian Institute of Technology, New Delhi-110 0 16, India Emails:
[email protected],in,
[email protected]
ABSTRACT This paper presents a method of preparing the absorbent core for an ultra-thin sanitary napkin using viscose-super absorbent fibre (SAF) blends with varying SAF percentages and mass per unit area (g/mz) of absorbent core. The viscose/SAF blended webs were sandwiched between two layers of nonwoven fabric to integrate and encapsulate it. The prepared napkin samples showed significantly better rates of absorption for saline solution even though the glass tube wicking (gravimetric) test gave only comparable results. The saturation absorption of the core also follows a definite trend, dependent on two variables, i.e. mass per unit area (g/m2) of the core web and proportion of SAF in the core web. Based on the results the absorption of the core has been optimized and equations have been developed for prediction of the absorption of the core fiom mass per unit area and the proportion of SAF in the core web. Key words: blending; card web; rate of absorption; sanitary napkin; saturation absorption; SAF; viscose
INTRODUCTION
Puberty comes with all kinds of changes in a woman’s body - including the way the body looks and smells. Once women begin menstruating, they need to use something to soak up the menstrual fluid - either a pad or a tampon. In Europe, some 42 billion sanitary napkins, tampons and panty liners were sold in 2004 compared to more than 35 billion products in 1997, according to Euromonitor International. The total European sales corresponded to approximately30% of global sales of sanitary protection products and reached more than $5.2 billion in 2004 compared with more than $3.9 billion in 1997. A closer look into the numbers shows that the biggest movements in feminine hygiene are the increasing use of ultra-thin pads and panty liners in place of thick pads. There is a general trend that sales of full-size or maxi pads are declining significantly across all of Europe, giving way for the ultra-thin products. Thanks to the presence of super absorbent polymers (SAP),these provide the expected absorption capacity. They also give girls and women the discretion, comfort and feminine design that has been sought after for generations. As raw material prices are increasing, sanitary protection product component suppliers are trying to ease this situation by developing technology to lessen the amount of S A P needed per unit. The objective of the present research is to study the absorption behaviour of sanitary napkin with different proportion of SAF and at different level of mass per unit area. The specific objective is to optimize the proportion of SAF and mass per unit area of the product for optimum absorption behaviour to have low cost product. The super absorbent fibre used in the present study is comprised of cross-linked polymerized acxylic acid. The results obtained in the present study are guidelines for developinghigh-absorbent sanitary napkin with reduced cost. 148 0 Woodhead Publishing Limited, 2010
EXPERIMENTAL Sample preparation The absorbent cores of sanitary napkin were prepared from multilayered carded webs to have required mass per unit area. The carded webs of viscose and SAF blend were prepared with varying SAF percentages and mass per unit area. The webs were carded a second time to achieve better fibre opening, better fibre alignment and homogenous blending. The card webs were then sandwiched between two layers of same nonwoven fabric to integrate the web and encapsulate it to get the absorbent core. Fig. 1 shows the schematic diagram of the cross section of the sandwiched layers of the absorbent core. It led to compaction of the web, providing a highly absorbent and thin core. The nonwoven fabrics used for encapsulation of webs in different samples were of two types, i.e. parallel laid viscose (type A - 20 g/m2) and random laid viscose (type B 60 g/mz) (made out of waste fibre) to get the absorbent cores. Nine different combinations of ViscosdSAF blended carded webs (type 1-9) were prepared and those webs were sandwiched between two types of nonwoven fabric layers, i.e. total 18 absorbent core samples were developed for study. The details of the samples are given in Table 1. This absorbent core was then swapped with that of an available sample (market sample) and the product was tested using the developed core. The nomenclature of the sample (e.g. Al) implies a sandwiched absorbent core sample of fabric type A and web type 1. The cross sections of the control sample (standard market sample which is the sandwich one) and the developed absorbent core (i.e. developed carded web sandwiched between two layers of nonwoven fabrics) are shown Figs. 2 and 3 respectively. The absorbent core of the controlled sample is a mixture of wood pulp and the granules of super absorbent polymer (SAP).The developed absorbent core was then inserted within the polymeric cover stock (one side perforated sheet and other side impermeable sheet) of an available sample (market sample). Fig. 4 shows the cross sectional view of napkin with developed sandwiched core. Test methods
The rate of absorption of water by the sample was tested using ASTM standard D 82494 for bibulous papers, by measuring the time required for the paper to absorb completely a specified quantity of water (it caters for a multi-ply specimen as well) 12. The water transport rate which correspondingly relates to vertical wicking is measured according to a vertical strip wicking test. One end of a strip (25mm wide x 170 mm long) was clamped vertically with the dangling end immersed to about 3 mm in distilled water. The height to which the water was transported along the strip is measured at 1,2, 3, 5 and 10 minute intervals and reported in centimeters3.Thehorizontal water transport rate of the fabric is measured by the “Umist Wettability Tester” using a 50 micro-liter distilled water droplet4. In the “Glass Tube Wicking ( G W ” test, the absorbent core mass was uniformly packed into a length of 1.0 cm inner diameter glass tube5. One end of this core packed tube was immersed vertically into a reservoir of 0.9% saline water. The mass of solution absorbed by a vertical wicking mechanism into the absorbent material was measured in terms of a weight change as a function of time. The saturation absorption of the absorbent core was
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Blended card web (Type: 1-9)
-
> Nonwoven fkbric
/
'
type (e.g. Aor B)
Figure 1: Layers of absorbent core
Table 1:Details of sandwiched absorbent cores Sample No. A1
A2 A3 A4
A5 A6 A7 A8 A9 B1 B2 B3
B4 B5 B6 B7 B8 B9
Nonwoven fabrics b e Mess
_. A A A A A A A
A A B B B B B B
B B
B
g/m2 20 20 20 20 20 20 20 20 20 60 60 60 60 60 60 60 60 60
Blended web details SAF % 10 30 50 10 30 50 10 30 50 10
30 50 10 30 50 10 30 50
Sandwichedcore details
Viscose
SAF
Totalmass
Y O
g/m2
%
%
g/m2
90 70 50 90 70 50 90 70 50 90 70 50 90 70 50 90 70 50
60
94 82 70 93.3 80 66.6 92.8 78.6 64.3 96.6
6 18 30 6.7 20 33.4
100 100 100 120 120 120 140
Viscose Totalmass 60
60 80 80 80 100
100 100 60 60 60 80 80
80 100 100 100
90 83.3 96 88 80 95.5 86.4 77.3
7.2 21.4 35.7 3.4 10 16.7 4 12 20 4.5 13.6 22.1
140
140 180 180 180 200 200 200 220 220 220
determined by immersing it in physiological saline (0.9% saline) for 30 minutes and then draining it for 30 minutes. The difference between the mass (g) after drainage and the mass (g) before immersion was taken as a saturation absorption. The time taken by the napkins to completely absorb 5 ml of 0.9% salt solution (i.e. absorption time) was measured according to the previously used ASTM standard D 824-94.
Figure 2: Cross sectional view of control sample
Figure 3: Cross sectional view of developed absorbent core
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Figure 4: Cross sectional view of napkin with developed absorbent core
RESULTS AND DISCUSSIONS Thicknessof dserent samples In a sanitary napkin, along with the mass per unit area and absorbency, the thickness is also very important characteristics. A thicker napkin is not at all desirable. The thickness values of the developed samples and the control sample are given in Table 2. For samples of both types A and B, we noticed a significant increase in thickness with an increase in the mass of blended web portion of the absorbent core. It is evident from the Table 2 that the thickness of the prepared samples is significantly lower, in most cases (Al-A9, and Bl-B3), compared to the control sample, which would be an added advetage for an ultra-thin sanitary napkin. It has also been observed that a change in content of SAF in the web does not affect the thickness of the sample significantly. So, the mean thicknesses for the same mass of sandwiched core samples have been reported.
Horizontalwicking The horizontal transport rate of transporting layer of control sample (layer 2) and the two types of nonwoven fabrics is given in Table 3. From the Table 3, it is observer that as fabrics A and B are made of viscose, which being absorbent in nature, give wide variation in wicking time depending on fibre alignment and mass per unit area. The parallel laid sample A, gives shorter time along the direction of the laid fibres whereas the random laid sample B, takes relatively higher time of wicking and approximately equal times in both directions. The higher time for travel in case of sample type B is mainly due to higher mass per unit area, where absorption is dominant and takes longer time for horizontal travel. The control sample shows wide difference in wicking characteristicsbetween X and Y directions. Table 2: Mean thickness of samples Sample Control sample A1 -A3 A4 - A6 A7 - A9
Meanthickness, mm 2.91 2.54 2.73 2.82
Sample
Meanthickness, mm
B1 -B3 B4-B6 B7 - B9
2.67 2.97 3.12
Table 3: Horizontal transport rate of samples SamDle
Laver
Volume ( A
Time (set)
xaxis Control sample
Layer 2
so
Fabric A Fabric B
--
50 50
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44.4 7.06 14.02
Yexis 2.02 3.23 16.98
Controlsample
Wicking height (cm)
FabricTypeA
2 1
-
-- -------C-----'-~
,,---z-
FabrictypeB
c
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Time (min)
Figure 5: Vertical wicking heights of control sample and nonwoven fabrics
Vertical wicking The vertical wicking characteristicsof transporting layer of control sample (layer 2) and the two types of nonwoven fabrics (TypeA and Type B) are given in Fig. 5. Capillary action is governed by the properties of the liquid, the fibre surface wetting characteristics,and the geometric configurationsof the porous medium Both fabrics A and B give comparable rates of vertical wicking with that of layer 2 of the control sample, though the random-laid sample B gives slightly higher rate than the parallel-laid one. This may be because of the differencein their mass per unit area.
'.
Glass tube wicking Fig. 6 shows the comparative glass tube wicking results of different developed sandwiched samples h m different blend proportions of web with 60 g/mz mass of web and the control sample. From the graphs plotted for the samples A and B types nonwoven fabrics (Fig. 6); we notice that with the increase in the SAF % of the web portion of the absorbent core, the rate of transport of the salt solution in the vertical direction increases (rate is measured by gravimetric method). This may be due to the much greater tendency of SAF to absorb the fluid compared to viscose fibre, even though there would not be a significant increase in the number of capillaries as the web mass remains unchanged. It can be seen that this general trend holds for both the fabric types and increasing mass per unit area of web, barring a few points of discrepancy. Figs. 7 and 8 show the similar trend for web mass of 80 glm' and 100 glm' respectively. O
I
h Tub. Wkkhg
1W
280
I:
ea
I
s o 0
50
100
150
ZM
Tbm (In uo)
Figure6:Glass tube Wicking comparison for 60 g/mz web mass
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I
I
Glus Tube Wcklng
0
50
100
150
200
250 I-Cli.JhalI
Time (In me)
Figure 7: Glass tube wicking comparison for 80 g/mz web mass Gk8s Tube Wlcking
Figure 8: Glass tube wicking comparison 100 g/mz web mass On comparing the rates of transport by samples having different web mass per unit area (g/mz) but same SAF %, no significant change is observed. This may be due to the very nature of the test, as the glass tube used for the tests is the same. This caused the amount of sample inserted into the tube to be nearly the same and hence a change in g/mz would not affect the relative rates. On comparing the developed samples with the original control sample, it is observed that B8 and B9 give better results in this test than the standard sample. These are made using random laid fabric in combination with a high SAF %. Samples B1, B2, B3, B7, A8 and A9 are comparable though slightly less than that of the control sample. Therefore, it is clear that on an average, the developed samples are comparable in performance in the Glass Tube Wicking test, as shown above.
Absorption time The time taken to absorb 5 ml of 0.9% salt solution by the napkin samples, i.e. absorption time, for aLl the developed absorbent core samples along with the control sample is given in Table 4. From this test, there are three important things to be noted. Firstly, it is clear that with an increase in g/mz of web portion of the absorbent core, the time taken by the samples to absorb 5 ml of 0.9% saline decreases significantly. Secondly, all the developed samples give an absorption time which is significantly lower than that of the control sample. Thirdly, the samples having the absorbent core containing the fabric of type B give signifcantly lower absorption times compared to those having fabric type A. This can also be inferred as fabric B gives higher vertical wickiflg rate than fabric A, as can be seen fiom F i g 5 Moreover, these tests have been
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Table 4: Absorption time developed and control samples Sample
Time
Sample
Sec
Control A1 A2
A3 A4
13.11 11.02 10.89 10.96 10.38
Time
Sample
SeC
A5 A6 A7 A8 A9
10.30 10.34 9.76 9.84 9.70
B1 B2 B3 B4 B5
Time sec 9.32 9.36 9.20 9.01 8.90
Sample
B6 B7 B8 B9
Time(=)
8.92 8.64 8.61 8.68
performed without the presence of a polypropylene distribution layer of the control sample thereby showing that the function of distribution of the fluid is being performed by the absorbent core itself. This not only demonstrates the superior performance of the developed sample but may also help in reducing the cost and thickness by eliminating an entire layer from the napkin. In practice, surfactants are often used to promote spreading of liquids on the surface of solids7. No definite trends were observed when the SAF % was increased.
Saturation absorption Saturation absorption for 0.9% saline solution of developed and control samples are shown in Fig. 9. It is clear from Fig. 9 that the saturation absorption increases with the increase in the proportion of SAF, due to obvious reason. Also, the type A samples show higher saturation absorption values than the type B samples. This is due to effective proportion of SAF in the type B samples are lower than correspondingtype A samples. As the saluration absorption is dependent on both overall proportion of SAF and mass per unit area of the core, it was tried to get the relationship between these parameters..The idea of getting the relationship was to predict the required saturation absorption and accordingly select the proportion of S A F and mass of sandwiched web. The least squaring technique was adopted for this and the relationship was found to be straight line. The relationship with the existing experimental data was found to be;
are the SAF?? and g/m2 of the overall sandwiched web. Hence, one can predict the absorption capacity of the absorbent cores prepared by present method, for any known values of total g/m2 of the core and the SAF %. This will help to optimize the amount of SAF needed and the g/m2 of the absorbent core according to the desired performance. where, Y is saturation absorption and XIand X2
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s
50
B1
B9
Sample
Figure 9: Saturation absorption developed and control samples
CONCLUSIONS The prepared napkin samples were mostly thinner or equivalent to the control sample. They showed significantly better rates of absorption for saline solution even though the glass tube wicking (gravimetric) test gave only comparable results. The saturation absorption of the core also follows a linear relationship, dependent on two variables, namely the mass per unit area and proportion of SAF. This w ill help to predict and optimize the absorption capacity of the core according to the desired performance. So, the present research has, therefore, indicates that the napkins performance can be enhanced by the use of blends of super absorbent fibre with some other relatively cheaper fibres.
REFERENCES 1 ASTM No. D 824 - 94: Standard Test Method for Rate of Absorption of Water by Bibulous Papers 1. 2 ASTM No. D 2177-99: Standard Test Method for Ink Absorption of Blotting Paper.
4 UMIST Wettability tester manual.
5 Technical Report 17: Chelsea centre for recycling and economic development, University of Massachusetts,April 2000.
6 R M Crow and R J Osczevski, ‘The interaction of water with fabrics’ Text Res J, 1998,68(4) 280-288.
7 K Slater, ‘Comfortproperties of textiles’, TextiZe Progress, 1977,9(4) 15.
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RETENTION OF ANIONIC SURFACTANT FOLLOWING GARMENT LAUNDERING AND ITS POTENTIAL EFFECT ON DERMATITIS SUFFERERS H D Rowe Manchester Metropolitan University, Manchester, UK ABSTRACT There are many causes of skin disorders and different forms from which a subject may suffer. initant Contact Dermatitis (ICD), an inflammatory condition caused when the skin comes into contact with various agents and Allergic Contact Dermatitis (ACD) which occurs when the body becomes sensitized to particular products are two conditions that can make the life of the sufferer a misery. The domestic detergent industry in the UK is vast. Although constituents vary from product to product the 'cleaning' component will, in general, be a surfactant of either anionic or non-ionic nature. It is known that at high enough concentrations surfactants are able to muse dermatitis but this is usually within industrial cleaning scenarios. Nevertheless the fabrics that our clothes are made from are often attractive to the chemical components of detergents and if insufKcientlyremoved from the fabric interstices when rinsed, may remain within the fabric structure and increase to potentially dangerous concentrations. This paper discusses the links between clothing, the skin and domestic detergents, describes a method developed to determine the retention pattern of anionic surfactants over progressive washes and finally presents results of tests conducted on cotton and polyester materials. Analysis of results shows cotton to retain more anionic surfactant to polyester at all concentrationsand all wash levels.
INTRODUCTION Dermatitis (also referred to as eczema) is a skin condition which affects a large proportion of the population at some time in their life. The British Skin Foundation's website contains the strap line; '8 million people in the UK suffer from some form of skin disease' (British Skin Foundation, 2006)'. contact Dermatitis which can be either irritant (ICD) or allergic (ACD) in nature are two afflictions for which detergents are sometimes blamed. Kremer et al. (2000)' agree that the number of sufferers of skin conditions is increasing and that the blame is often put on detergents. Bauer et al. (2003Q state categorically that 'ICD is an inflammatory response of the skin after contact to various irritant factors, such as detergents As soon as a skin reaction is brought to the attention of a doctor probably one of the first things they will ask is "haveyou changed your washingpowder? (Natiod Eczema Society, 2003)4. Those who work in wet conditions or spend fiequent amounts of time using cleaning fluids are certainly at risk and a considerable amount of work time can be lost due to occupational exposure to detergents (Wigger-Alberti et al., 2OOO)*. But will the detergent components remaining within our clothes after laundering have similar effects? The main cleaning agent in a typical home laundry detergent is the surfactant which in most domestic products will be either anionic or non-ionic in nature. Surfwtants lower the surface tension of water allowing the fabric surface to be wetted out and assist ....I
If
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in loosening the soil, Builders are included to help soften water and prevent soil being redeposited on the fabric after release. OrigLnally phosphate based, these are increasingly being replaced by zeolites. Biological @io) detergents contain enzymes to help digest protein, fat and starch based stains. Sometimes bleaches are added to remove coloured stains but are not necessitated or desired for washing coloured garments. Finally there are a number of additional constituents that may be present such as foam regulators, optical brightening agents and perfumes. There is massive choice for the consumer not only in the case of bio versus non-bio but also in the form that the detergent takes: powder-; liquid; tablet; gel. Although some consumers favour non-bio products over biological (assuming that it is the enzymes that cause dermatologicalproblems), several researchers have disputed this (Jakobi and Lohr pp 190-194, 19876;Anderson et al., 1998)'. In the case of surfactants, Matthies (2003, ~ 1 2 4 admits )~ that irritancy against surfactants is a common phenomenon at threshold concentrations. Surfactants are known to impair barrier function of the skin and induce irritation. Once adsorbed onto the skin the surfactant emulsifies the lipids on the skin surface leading to a rough, scaly, dry surface (Ale et al., 1997)9.However Jakobi and Lohr (1987) and Porter (1994)" insist that the levels of surfactants used in domestic detergents are safe. There is clearly some disagreementamongst researchers. The retention of surfactants on clothing may pose problems not previously suspected. Kremer et al. (2000) and Bircher (p168,2003)' suggest that detergent residues are not completely removed from fibres on rinsing. The reasons for this will be due to washtrinse process and also to the complexity of the fabric substrates that detergents find themselves applied to. Fibre content, yam structure, fabric construction, dyeing, printing, mechanical and chemical finishing processes can all affect the way aqueous solutions of detergents will attach themselves to clothing. Whilst the results of some research on detergent and clothing substrates is reported (Kurz, 200312 ;Matthies, 2003) the author believes that not until quite recently has the effect of fibrelfabric composition been considered as a contributing factor to dermatitis. Frequently the advice given to eczema sufferers is to wear cotton clothing (British Skin Foundation, 2006) but to quote Wffliams (2001)'3 in his review of treatments of atopic eczema "there was no evidence to support any clear clinical benefit on the use o j . .cotton clothing as opposed to soft-weave synthetics... . . The experimental work that follows tends to agree. I'
EXPERIMENTAL For the experimental part of this study it was decided to concentrate on the retention of anionic surfactant on fabrics used in clothing. The most popular fibre types for apparel wear are the natural cellulosic fibre, cotton and the synthetic polymer, polyester. Often these two are combined together by blending in various proportions, the blend percentage depending on the intended enduse (Rowe, 2006)14. However to simplify the evaluation in this initial study it was felt necessary to use 100 % cotton and 100 % polyester fabrics. As mentioned previously, fabric constructions vary considerably and so it was important to select fabrics as similar as possible in weight and construction so that the evaluation could be concentrated on the effect of fibre type only. Fabrics were sourced from a local manufacturer, in greystatc. Each was plain woven, approximately 140 g/mz area density with 30 x 30 warp and weft threads per cm. The assurity of the greystate of the fabrics meant that neither had been subjected to dyeing, printing or chemical finishing processes which might affect retention levels. However it was clear that they may still 0 Woodhead Publishing Limited, 201 0 157
contain remnants of spinning oils and other auxilliary spinning I weaving products which necessitated the fabrics being thoroughly scoured prior to testing. it was found during the course of preparing the test regime that scouring the fabrics prior to testing reduced the presence of pre-existing anionic surfactant by over 75 %. In order to simulate the concentration of anionic surfactant present in a normal wash load advice from washing powder manufacturers was sought. Simply by reading consumer information on the side of packs it was found that for a normal wash lOOg of product (containing between 5 - 15 % anionic surfactant) should be used. Calculations were made in order to determine the levels of concentrationsneeded for this bench scale laboratory evaluation and it was found that subjectingthe 2 fabrics to wash cycles with 0.2 g/L; 0.4 g/I, ;0.6 g/I, of surfactant would cover the same range that a garment might encounter in normal domestic washing. Granular laboratory standard anionic surfactant was used for this purpose. No other detergent component was added. Preliminary tests using a standard Wascator washing machine for the wash cycles showed that results could be affected because of contamination of the drum and pipes etc by remnants of surfactant from p v i o u s launderings. It was therefore decide to conduct wash cycles in a bench scale Gyrowash machine which enabled thorough cleaning to take place between wash loads. A 40 * C main wash followed by 5 x cold, distilled water rinses was adopted. Wash cycles were repeated up to 5 x on all samples and all samples hung to dry after each cycle. All sizes / weights of fabric, liquor capacities , surfactant concentrations etc were scaled down appropriately to best simulate standard washing practices. Following each wash cycle it was necessary to extract the retained surfactant from the fabric. This was done by boiling with distilled water for 30 minutes in a water cooled soxhlet extractor. The product of this extraction was then divided into several samples for repeat testing and each subjected to measurement of anionic surfactant content using a HACH Colorimeter . This preparation process required 300 mls of the sample under test to be introduced to a separatory funnel together with 10 mls of buffer solution, the contents of one detergent reagent pillow and 30 m l s of benzene. The contents were mixed by gently shaking and then allowed to separate over a period of 30 minutes. After this time the lower, aqueous layer was discarded and the top benzene layer transferred to a phial and placed in the colorirneter for measurement. To recap, the experimental work included : J J
J J J
J
Selecting 2 similar greystate woven fabrics in 100 % cotton and 100 % polyester. Subjectinggreystate fabric to pre-washing Washing fabric in a controlled environment using 3 concentrations of anionic surfactant, one wash temperature and progressive wash cycles. Subjecting samples of each to an extraction process using a soxhlet extractor Subjecting the resultant liquor to a strict preparation for measurement process by associating the anionic surfactant component with crystal violet dye and extracting the ion-pair complex into benzene. Subjecting the benzene layer to colormetric analysis using a portable HACH colorimeter
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RESULTS
Table 1 Average amount of anionic surfactant extracted from washed cotton fabric in mg/L
Concentmtipn of anionk surfbetant added to wash cycle in g/L 0.2 0.4 0.6 Wash I Wash 2 Wash 3 Wash 4 Wash 5 - __
0.38 0.56 0.63 0.89 I .09
0.75 0.84 0 75 0.9 I
0.73 1.16 1.09 I .09 I -.36 -.
1.13
-
Table 2 Average amount of anionic surfactant extracted from washed polyester fabric in mgil. ______
___
Wash I Wash 2 Wash 3 Wash 4 Wash -- .5
[-test
-
Concentration of anionic surfactant added to wash cycle in g/L 0.2 0.4 0.6 0.25 0.3 1 0.35 0.28 0.24 0.24 0.23 0.24 0.25 0.38 0.46 0.3 1 0.29 0.2 I 0.39 _ _ ~ _ _ . __ ~
~
Table 3 signiticance of difference between results of wash I and wash 5 at each anionic concentration level in wash cycles for both cotton and polyester fabrics
conc. of anionic surfactant in wash cycle 0.2 0.4 - 0.6
t-value and indication of significance of difference between results of Wash 1 and 5 in both fabrics Cotton Polyester t-value sig t-value Sig 8.02 4.35 5.42
*** ** **
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2.10 0.50 3.20--
*
-
Table 4 t-test significanceof difference between results of cotton and polyester fabrics at 3 levels of anionic concentration and over 5 wash cycles key : - no significance ; * sig difference ;** highly sig diff; *** very highly sig diff
Wash cycle
number__
t-value and indication of simificance of d i f f i n c e between results for cotton and paly&r at each amcentration level (&I,)
0.2 [-value
1.46 6.40 3.57 6.90 10.96 .___ -
d
0.4
sig
**
* **
***
t-value
4.35 5.9 I 6.40 1.57 45.4
-
0.6 sig
**
** **
***
t -va I ue
9.92 6.2 1 6.64 9.53 9.76
sig *** ** ** *** ***
-
l m I L R n
...
Retained anion i surfactant in cotton an2 polyester fabrics over progressive washes
DISCUSSION Tables 1 and 2 show the amount of anionic surfactant removed from the cotton and polyester fabrics using soxhlet extraction methods subsequent to a normal wash and rinse process. It is assumed that had the detected anionic surfactant not been forcibly extracted from the fabrics at least this amount would still be retained within the material following domestic washing. Immediately it is clear that even at the lowest concentration (0.2 g L ) the cotton fabric has released (and therefore is assumed to 160 0 Woodhead Publishing Limited, 2010
normally retain) 2 to 3 times the surfactant content than the polyester fabric. At the higher applied concentration (0.6 g/L) this rises to around five times as much. Considering the effect of increasing initial concentration of anionic surfactant on the cotton fabric (Table l), the retention appears to consistently increase both as concentration of anionic surfactant increases and as number of washes increases. The difference between the first wash and fifth wash has been statistically tested for significance using a 2 tailed t-test. This has been repeated for each anionic surfactant concentration level. The t-value results and an indication of their significance can be seen in Table 3. Turning attention to the polyester fabric results (Table 2). Despite the increase in initial anionic surfactant concentration levels, and the repeated wash cycles, the amount of anionic surfactant released from (and therefore assumed to be normally retained within) the polyester fabric, after extraction, remains fairly consistent, hovering around the 0.3 mgL level. Again the statistical significance of the differences between wash 1 and 5 at each concentration can be seen via t-test results in Table 3. This shows us that increasing the number of wash cycles increases the amount of retained surfactant to a highly significant, if not very highly significant degree in the case of cotton but only shows some degree of significanceat the 0.6 g/L level for the polyester fabric. To determine whether there is a real difference in the retained anionic surfactant between cotton and polyester at all initial anionic surfactant concentrations and across all 5 washes, significance test results are reported in Table 4. This indicates that there is a highly significant difference between the retained anionic surfactant levels of cotton and polyester both at the higher initial concentration (0.6g/L)level and at the higher wash cycle ( 5 ) level, with cotton retaining the most. Figure 1 illustrates the obvious difference in retention levels between the two fabric types. The gross morphological structure, fine structure and chemical composition of cotton suggests that applications from aqueous solutions will readily be attracted to the fibre, often becoming chemically attached (as in the case of some dyes and finishes) but in any case readily being absorbed into the amorphous areas of the fibre and particulates, especially, are able to be trapped within the convoluted outer structure of the fibre. For the same reasons that cotton readily lends itself to such invasion, polyester's gross morphological, fine and chemical structures do not. Relatively simple, linear molecular chains give rise to regions of high crystallinity (and therefore strength) ; molecules consisting of chemical sites relatively unattractive to moisture (long well understood because of its inability to dye without some assistance from high temperature and pressure) and a smooth, featureless outer structure (easily observed using optical microscopes), means that, before seeing the results presented here, it could have been postulated that cotton would retain the most. What is of especial interest is that after the initial take up by polyester neither increasing concentration nor increasing number of wash cycles appears to encourage further take up. Indeed the fibre appears saturated, unable to accept any more anionic surfactant, which could be good news for those who suffer dermatologicalproblems as a result of surfactant contact. This research is in its initial stages. Now that a test regime has been developed and tested what will be interesting to see next is whether altering fabric strucme (using knit as opposed to woven fabric) shows up any anomalies. It is also important to see what effects other fibre types have on the results. Would other synthetics behave in a similar manner to polyester and would say viscose, a manmade fibre but with a cellulosic 0 Woodhead Publishing Limited, 201 0 161
chemical composition, behave like cotton? It is hoped that results of tests on these other materials will be available within the next 12 months. Qualitative research is also important to this study. The researcher intends to gather information from dermatitis sufferers to determine what fabric choices they make and what washing habits they adopt. Interviews with Dermatologists will be sought in order to gather evidence of the advice they give to patients on what fabrics they should wear and laundry products they should favour. Eventually it is hoped to propose the ideal fabric/ launderingprocesses to reduce the effect of detergents on dermatitis sufferers.
CONCLUSIONS Some forms of contact dermatitis are exacerbated by fabric detergents. The dermatitis sufferer is confronted with a massive choice of both apparel fabrics and washing detergents to choose from.If detergents are preferentially absorbed into particular fibre types or inefficiently rinsed from them harmll residues may re& Tests have been conducted on cotton and polyester fabrics to determine the retention levels of the anionic surfactant component of detergentsat 3 levels of concentrationand over a series of wash cycles. It has been found that the cotton fabric retained up to five times as much surfactant as polyester. Polyester appears to become saturated with surfactant at low levels and is unable to retain M e r amounts. This information could form the basis of preferred fabric choices for dermatitis sufferers. The research will continue with a survey of buying and washing habits of dermatitis patients and further laboratory work on a range of fibre types and fabric constructions
REFERENCES 1 British Skin Foundation 2006. http:llwww.britishskinfoundation.org.uWabout/eczema-overview.asp accessed 19.09.2006
2 J bemer, W Matthies, & I Voigtmann, ‘New perspectives on skincompatible detergents for sensitive-skin’ Tenside Surfactants Detergents, 2000 37(6) 350 -356.
3 A Bauer, J Bong, P J Coenraads, P Elsner, J English, H C Williams, 2003 ‘Interventionsfor preventing occupational irritant hand dermatitis’.(protocol). Cochrane Dutabuse of Systematic Reviews 2003, Issue 3 . Art. No. : CD004414. DOI: 10.1002/1465 1858.CD004414. 4 National Eczema Society 2003 ‘Factsheet- Washing Products and Fabric Softeners’ Nov 2003, London :National Eczema Society.
5 W Wigger-Alberti, A Krebs, P Elsner, ‘Experimental irritant contact dermatitis due to cumulative epicutaneous exposure to sodium lauryl sulphate and toluene : single & concurrent application’ British Journal of Dermatology, 2000 143 55 1-556. 6 G Jakobi, & A h h r , Detergents and Textile Washing - Principles & Practice VCH Publishers, Cambridge 1987.
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7 P H Anderson, C Bindslev-Jenson, H Mosbech, H Zachariae, K E Anderson, ‘Skin symptoms in patients with atopic dermatitis using enzyme-containing detergents’ Acta Dermato-Venereologica, April 1998 78 1 60-63. 8 W Matthies, ‘Irritant dermatitis to detergents in textiles’ pp 123-138 in Textiles and the Skin, P Elsner, K Hatch and W Wigger-Alberti,( Vol.Eds), in Current Problems in Dermatology, vol3 1, Burg, G. (Series Ed), Basel : Karger. 9 S I Ale, J-P K Laugier and H I Maibach, ‘Differential irritant skin responses to tandem application of topical retinoic acid and sodium lauryl sulphate : 11, Effect of time between first and second exposure’ British Journal of Dermatology, 1997 137 226-233. 10 M R Porter, Handbook of Surfactants 2”* ed Glasgow: Blackie Academic & Professional 1994.
1 1 A J Bircher, ‘Cutaneous immediate-type reactions to textiles’ 166170 in Textiles and the Skin, P Elsner, K Hatch, and W Wigger-Alberti, (VoLEds), in Current Problems in Dermatology, 31 G Burg, (Series Ed), Basel :Karger, 2003. 12 J Kun, ‘Laundering in the prevention of skin infections’ 64 -81 in Textiles and the Skin, P Elsner, K Hatch, and W Wigger-Alberti, (Vol.Eds), in Current Problems in Dermatology, 31 G Burg, (Series Ed), Basel : Karger 2003. 13 H Williams, 2001 ‘Systematicreview of treatments of atopic eczema.’ The Research Findings Register. Summary number 468. Retrieved 19 September 2006 f?om
http:l/www.ReFeR.nhs.uk;NiewRecord.asp?ID=468. 14 H D Rowe, ‘Detergents, clothing and the consumer with sensitive skin’International Journal of Consumer Studies, 2006 30 369-377.
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PREPARATION OF PROTECTIVE DISPOSABLE HYGIENE FABRICS FOR MEDICAL APPLICATIONS M. Montazer’, F. -chi2,
F. Siavoshi3
’ Department of Textile Engineering, Amirkabir University of Technology, Tehran, IRAN * South branch of TehranAzad University, Tehran, IRAN
Deptertment of Science, Tehran University, Tehran, IRAN
ABSTRACT One way for disease transmission from one person to another is using clothes by different people in hospitals. Using of the disposable clothing products with antimicrobial finishing can provide a good protection against transmission of diseases for both the surgery team and the patients. When it comes to the medical market, nonwovens are exactly what the “doctor ordered”. Both manufacturers and consumers are already awam of the many benefits nonwovens offer to the medical market. When compared to textiles, nonwovens are lower in cost, easier to use, more versatile, safer and feature better disposability. With this in mind, it is no wonder that nonwovens are found in hospital surgical drapes and gowns, protective face masks, gloves, surgical packs and bedding and linens. In this research, cetyl trimethyl ammonium bromide (CTAB), as an antimicrobial agent is applied on polyester, polypropylene and viscose non-woven fabrics alone and in combination with a Fluorochemical (FC 1112). The antimicrobial, water and blood repellency of the treated samples were investigated. To reveal the antimicrobial properties of the treated samples, the zone of inhibition and reduction of bacteria were measured with S. aureus, E. coli and P. aeroginosa. The results showed a good antimicrobial property on different concentration of CTAB solutions (l%, 2%, 4% and 8%). Application of CTAB with concentration of (O.S%, 1% and 2%) on polyester, polypropylene and viscose nonwoven fabrics indicated a reasonable antimicrobial effect. Co-application of CTAB with fluorochemical on different samples also showed a good antimicrobial,water and blood repellency properties.
INTRODUCTION Textile goods are excellent substrate for growing microorganisms. For the last fifty years, the prevention of microbial attack on textile materials has become increasingly important to consumers and textile producers [l]. Clothing such as socks and underwear faced with odor €rom body perspiration. Currently there is also an interest in protecting health care workers from diseases that might be carried out by patients. Especially for surgical gowns, there is an increasing need to protect medical staff from infection by blood borne pathogens such as M V and HBV. Gowns should be able to prevent stricke through or wetting out of the fabric, and so surgical gown materials should not only have antimicrobial properties but also blood barrier properties [2]. In addition the textile wed in hotels, transportation and biological institutionneeds antimicrobialtextiles [A. Nowadays nonwoven fabrics are the most commonly used textiles for surgical gowns, patient drapes, laboratory coats, coveralls, and other kinds of protective clothing [S]. Moylan et al, in a study of 2181 clean and clean-contaminated general surgical operations, showed that there was a significantreduction in the post-operative infection rate in both categories of operations when a disposable gown and drape system was 164 0 Woodhead Publishing Limited, 2010
used compared with a cotton system. The risk of developing a wound infection was 2.5 times greater with the cotton system than with the disposable system [l 11. Polyethylene terephethalate is a preferred textile fiber in many durable applications of nonwoven for its ease of use and compatibility with other fibers. Although Polyester has excellent mechanical strength and good stability but its end use capacity is limited due to the difficulties associated to functional finishing i.e. lack of polar groups on the surface and poor wet ability [9]. Fluorochemid are mostly used as repellent agents in textile finishing, which satisfy the demand for high water repellency and also impart oil and soil repellency to textiles 161Different antimicrobial agents have been applied to obtain antimicrobial properties to textile [3]. Among them, the quaternary ammonium salts of cationic surfactants are widely used in antimicrobial finishing of textiles [4]. Quaternary ammonium salts exhibit marked antimicrobial activity against a wide range of bacteria, fungi, and viruses [lo]. In this study cetyltrimethyl ammonium bromide (CTAB) was used as an antimicrobial agents. This agent has been frequently used in textile dyeing and finishing as either softener and leveling agents or as disinfectants, but has not been employed as an antimicrobial agent on nonwoven fabrics [8].
EXPERIMENTAL The polypropylene and polyester melt blown and raw and dyed (direct) viscose nonwoven fabrics, cetyl trimethyl ammonium bromide (CTAB) as an antimicrobial finish agent (Fig.l), citric acid (5%), and fluorochemical namely FC 1112 (Organic Kimia Co.) as a water and blood repellents were used. 0r-
'343
H~C(CH~~,~AJ+N~ AH3 Figure 1- Chemical structure of cetyl trimethyl ammonium bromide
To prepare the antimicrobial finish, the samples were padded through baths of 0.5, 1 and 2% CTAB solution with wet pick up of 130%, dried at 80 - 85' c for 3 minutes and cured at 145-15O'c for 3 minutes. We also used both the fluorochemical repellent and the antimicrobial agent in one bath. The antimicrobial properties of samples were evaluated quantitatively by measuring the reduction rate in the number of colonies and qualitativelyby showing a clear zone of inhibition around the samples. In order to evaluate the antimicrobial properties of the samples, three common pathogen bacteria were used including: Staphylococuse aureus (gram positive), Escherichia coli (gram negative) and Pseudomonas aeroginosa (gram negative). The reduction rate of bacteria growth under agar plates was calculated by the following equation: R %=( A-B)/Ax 100 Where A is the number of bacteria colonies fiom an untreated fabric, and B is the number of bacteria colonies from the treated fabric. The water and blood drop absorption was measured by the time of absorption of the droplet on the fabric surface.
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Results and discussion The antimicrobialand fluorochemical finshes used in this study were mixed in a single bath and could be applied to nonwoven fabrics to impart the desired properties. The results of antimicrobial activities of polyester and polypropylene treated fabric with different bacteria are indicated in Tables 1-5. The inoculum was a nutrient broth culture containing 0 . 5 1~06, 1x 1O6 and 1.5 x 10 6 / d colony-formingunits (CFU) of the bacterium. The results show that 1% and higher concentration of CTAB on both polyester and polypropylene fabrics reasonably inhibit the growth of E. coli at pH=7 and S. aureus and P. aeroginosa at pH=5.5 (pH=5.5 is the pH of body skin). This test can not be used for viscose nonwoven because of disturbing effect of adhesive used for fabric production. The zone of inhibition also observed for each sample. The results are shown in Table 6, the sign (+) represented for the sample with formation of zone of inhibition and the sign (-) for the sample without formation of zone of inhibition. The results show a clear zone of inhibition around the treated samples with different concentration of CTAB. It was noted that an increase in CTAB concentration leads to an increase in the zone of inhibition reflected by enlargement of the diameter of zone of inhibition. It was also found that the effectivenessof the antimicrobid finish of CTAB can not be influenced by the level of the fluorochemical finish. Table 1. Antimicrobial activity of polyester and polypropylene fabrics treated with CTAB against E. coli at pH=7. 0.5 1 2 CTAB % Reduction of 90 99.9999 99.9999 bacteria on polypropylene Reduction of 90 99.9999 99.9999 bacteria on Dolvester Table 2. Antimicrobial activity of polyester and polypropylene fabrics treated with CTAB against S. aureus at pH=5.5. CTAB Yo 0.5 1 2 Reduction of 90 99.9999 99.9999 bacteria on polypropylene Reduction of 90 99.9999 99.9999 bacteria on polyester
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Table 3. Antimicrobial activity of polyester and polypropylene fabrics treated with CTAB against P. aeroginosa at pH=5.5. CTAB % 0.5 1 2 Reduction of 90 99 99.99 bacteria on polypropylene Reduction of 90 99 99.99 bacteria on polyester Table 4. Antimicrobial activity of polyester and polypropylene fabrics treated with mixture of CTAB and FC1112 against E. coli at pH=7. CTAB % 0.5 1 2 Reduction of 90 99 99.9999 bacteria on polypropylene Reduction of 90 99 99.9999 bacteria on polyester Table 5. Antimicrobial activity of polyester and polypropylene fabrics treated with mixture of CTAB and FC1112 against S. aureus and P. aeroginosa at pH=5.5. CTAB Yo 0.5 1 2 Reduction of 90 90 99.9999 bacteria on polypropylene Reduction of 90 90 99.9999 bacteria on polyester The results for water and blood drop absorption are presented in Table 7. The results showed that application of fluorocarbon on both polyester and polypropylene fabrics could produce a fabric with acceptable water and blood repellent properties as the time of water and blood absorption increases rapidly. The surface tension of water is 72 dydcm and natural blood is around 52 dyn/cm. This means that these materials can spread rapidly on the polyester and polypropylene fabric surface. Application of fluorochemical reduces the surface energy of the fabric and do not permit the water or blood droplet to adsorb and spread on the fabric surface. With application of sufficient amount of fluorochemical on the fabric surfaces, It is possible to produce a fabric with water and blood repellent properties. This research showed that the amount of 2% fluorochemical was sufficient to produce a fabric with reasonable water repellent Property. 0 Woodhead Publishing Limited, 201 0 167
The results of co-application of fluorochemical with CTAB indicated that these two chemicals have a good compatibility and could produce a fabric with multifunctional properties, as the fabric is antimicrobial as well as water and blood repellent. Table 6. Antimicrobial activity of polyester, polypropylene and white and dyed viscose fabrics treated with CTAB measured by AATCC 90 (zone of inhibition) Fabric Percent of materials bacteria CTiU3
FC
Polypropylene
0
0
Polyester
0
0
White Viscose
0
0
Dyed Viscose
0
0
Polypropylene
3
0
Polyester
3
0
White Viscose
3
0
Dyed Viscose
3
0
Polypropylene
2
0
Polyester
2
0
White viscose
2
0
Dyed Viscose
2
0
Polypropylene
1
0
Polyester
1
0
White Viscose
1
0
+
Dyed Viscose
1
0
+
Polypropylene
0.5
0
Polyester
0.5
0
White Viscose
0.5
0
Dyed Viscose
0.5
0
Polypropylene
2
2
+
Polyester
2
2
White Viscose
2
2
+ +
Dyed Viscose
2
2
+
P.aeroginosa
E.coli
Saureus
+ + + + + +
+
+ + + + + +
+ +
4-
+ + + + + + +
+
+ + + +
+ +
+ + + +
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Table 7. Droplet absorption time for the samples treated with Fluomchemical andor TAB Time of absorption (seconds) % FC Water Blood Fabric 0 Less than 5 Less than 5 Polypropylene Less than 5 0 Less than 5 Polyester Less than 5 0 Less than 5 White Viscose Less than 5 0 Lessthan5 Dyed Viscose More than 1800 1 More than 1800 Polypropylene More than 1800 1 More than 1800 Polyester 1 More than 1800 More than 1800 White Viscose More than 1800 1 More than 1800 Dyed Viscose More than 3600 2 More than 1800 Polypropylene More than 3600 2 More than 1800 Polyester More than 3600 2 More than 1800 white Viscose More than 3600 2 More than 1800 Dyed Viscose More than 3600 3 More than 3600 Polypropylene More than 3600 3 More than 3600 Polyester More than 3600 3 More than 3600 White Viscose More than 3600 3 More than 3600 Dyed Viscose More than 1200 2%FC+2%CTAB More than 1200 Polypropylene More than 1200 2%FC+2%CTAE3 More than 1200 Polyester More than 1200 White Viscose 2%FC+2%CTAB More than 1200 2%FC+2%oCTAB More than 1200 More than 1200 Dyed Viscose CONCLUSIONS Synthetic fibers such as polypropylene and polyester are commonly used in the construction of surgical drapes and gowns as well as viscose. Antimicrobial nonwoven fabrics were prepared by directly incorporation of a qurtemary ammonim salt namely, cethyl trimethyl ammonium bromide, on polyester and polypropylene and viscose nonwoven fabrics. An interesting observation is the clear zone of inhibition and excellent reduction of bacteria growth on polyester and polypropylene fabrics. It is apparent that the antimicrobial activity of CTAB is bactericidal in nature and not bacteriostatic. CTAB was effective as antibacterial agent on E.coli for three different fabrics. However CTAB was not effective on S. aureus and P. seudomonas when applied to viscose fabrics which may suggest that nature of substrate influence on the antibacterial activity of CTAB. The antimicrobial and fluorochemical finishes used in this study were miscible in a single bath and could be applied to nonwoven fabrics to impart the desirable properties. REFERENCES 1 H S Seong, J P Kim and S W KO,‘Synthesis of quaternary ammonium derivative of chito-oligosaccharideas antimicrobial agent for cellulosic fibers’, Textile Res J 1999 69 483-488. 2 B C Gosawami J Suryadevara, T L Vigo, ‘Determination of Poisson’s ratio in thermally bonded nonwoven fabrics’, Textile Res J,51 1981 54(6) 391-396. 0 Woodhead Publishing Limited, 201 0 169
3 T Nakashima, Y Sakagami, H Ito, M Matsuo, ‘Antimicrobial activity of cellulose fabrics modified with metallic salts’, Textile Res 4 2001 71 688-694. 4 M Diz, M R Infante,P Ena, A Manresa, ‘Antimicrobialactivity of wool treated with a new thiol cationic surfactant’, Tatile Res J, 2001 71 695-700.
5 S Tan, G Li, J Shen, Y Liy M Zong ‘Study of modified polypropylene nonwoven cloths’, Journal ofApp1 Polymer Sci, 2000 77,1869-1 876.
6 S Lee, J S Cho, and G Cho, ‘Antimicrobial blood repellent finishes for cotton and nonwoven fabrics based on chitosan and fluropolymm’, Textile Res J, 2000 69 104-112. 7 G Sun et al, ‘Antimicrobial medical - use textiles’, The 6* Asian c o d Hong Kong, 22-24, Aug 2001. 8 P Zhu and G Sun, ‘Antimicrobial finishing on wool fabric using quaternary ammonium salts’, Journal ofApp1 Polymer Sci, 2004 93(3) 1038-1041.
9 Y Shin, K Son, D I Yoo, S Hudson, M McCord, S. Matthews and Y. J. whang, ‘Functional finishing of nonwoven fabric accessibility of surface modified PET spunbond by atmospheric pressure plasma treatment’, Journal of Appl Polymer Sci, 2006 100 4306-4310. 10 Y A Son and G Sun, ‘Durability of anthicrobial on nylon66 fabric: Ionic interaction with quaternary ammonium salts’, Journal ufAppl Polymer Sci, 2003 90 2194-2199. 11 J A Moylan, K T Fitzpatrick and K E Davenport, ‘Reducing would infections. Improved gown and drape barrier performance’, Arch Surg, 1987 122 152-157.
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DEVELOPMENT OF SURGICAL CLOTHING FROM BAMBOO FIBRES K. Ramachandralu PSG College of Technology, Coimbatore, India ABSTRACT Sanitation and hygiene are the most important aspects of health. They display greater significance in medical field particularly during the course of surgery and post surgery. The patients undergoing surgery and also the surgeons and paramedical staff assisting surgery need secure protection against infections. The urgent need is to provide them with suitable surgical wears that can natwally resist the growth of infectious microbes. The advent of bamboo fibre which is bestowed with the inherent property of inhibiting growth of bacteria by its natural ability of sterilization and bacteriostasis qualify its usage in apparel and home textiles and hygiene products An attempt has been made in this research work to extend its usage to medical textiles, particularly to develop surgical robe, face mask and caps- from bamboo fibre. 30s Ne yams were produced out of bamboo fibre and cdton in five different types namely, 100% bamboo fibre, and bamboo I cotton blends of 80:20, 70:30,60:40 and 5050 and knitted into single jersey fabrics. All these fabric samples were evaluated for their anti bacterial characteristicsqualitatively by parallel streak method. The results reveal that fabric made of 100% bamboo fibre is able to inhibit bacterial growth effectively, where as in case of blended fabrics it is observed that as the percentage of cotton increases, the antimicrobial effectiveness decreases. Subsequently, surgical wears such as surgeon's gown, face mask and caps were constructed out of 100% bamboo fabric. The anti bacterial assessment of the surgical wears made fioml00% bamboo fibres was carried out and compared with commonly used surgical wears made from 100% cotton after using them in actual hospital condition during a surgery. Their effectiveness towards inhibiting bacterial growth were evaluated by Blood agar plate method qualitatively and quantitatively as well as by turbidity method. The results revealed that the use of 100% bamboo fibre in surgical wears inhibits the growth of bacteria. It has been proven in this research work that surgical wears could be manufactured from bamboo fibres and effectively used for better sanitation and hygiene in hospitals. INTRODUCI'ION
Thanks to the extensive research by fibre scientists, the dawn of the 21" century has witnessed the introduction of many new fibm possessing improved functional characteristics. Bamboo is one such new generation fibre with cellulose base, regenerated h m bamboo stems. It possesses certain improved characteristics l g such as better moisture absorption, quick drying, excellent anti microbial, anti odour, ultra violet proof, cool sensation on skin, soft feel etc. Bamboo fibre derives its antibacterial strength h m a unique anti bacterial and bacteriostatic bieagent called bamboo kun. The manufactureIs of this fibre'*23claim that it can be used for producing intimate apparels such as unckrwears , banians, socks etc., home textiles such as bath robes, mats, towels etc., hygiene and sanitary products such as sanitary napkins, bandages, gauzes etc., and summer clothing for pregnant
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women and children. Unfortunately there is a dearth of information / data on the real effectiveness of this fibre on various applications. No literature other than the manufacturer’s claim are available. Hence an attempt has been made in this research work to spin this fibre and its blends with cotton into yarns and convelt these yarns into single jersey fabrics and to evaluate their various characteristics and particularly their anti bacterial characteristic. In this research work, exploiting the antimicrobial characteristic of bamboo fibre, surgical wears such as surgeons gown, mask and caps were developed out of the single jersy fabrics made of 100% bamboo fibres and their effectiveness towards inhibiting bacterial growth in actual hospital conditions were evaluated. This paper is based on the above developmental work and evaluation of the yarns and fabrics made of bamboo fibres and bamboo cotton blends and their subsequent characterizations, particularly their anti bacterial characteristics.
MATERIALSAND METHODS 30s Ne yarns were produced out of 1.5 D Bamboo fibres of 38mm cut length and cotton in five different proportions namely 100% bamboo fibre and bamboo / cotton blends of 80:20, 70:30,60:40 and 5050 in actual mill conditions with the same process parametersand tested for their physical characteristics such as tenacity, elongation, evenness and imperfections They were knitted into single jersy fabrics and dyed using reactive dye. These fabrics samples were evaluated for their mechanical characteristics such as abrasion resistance, pilling resistance and bursting strength, wettability and washing fastness using standard testing instruments following standard testing methods 436. Then the samples were tested for their anti bacterial characteristics qualitatively by Parallel Streak Method using the organism Staphylococcus a m u s following AATCC 14711998 procedure5. Based on the results in terms of their effectiveness to inhibit the growth of bacteria, the bamboo / cotton blend proportions were optimized. As the fabric made of 100% bamboo fibre was found to be effective in inhibiting bacterial growth, it was considered for the development of surgical wears. From the fabric made h m 100% bamboo fibres, surgeons gown, caps and masks were constructed. These wears were used during a surgery in a hospital along with the surgical wears made from 100% cotton, which are regularly used by the hospital. After usage these wears were evaluated for their effectivenesstowards inhibiting bacterial growth 1” X 1” qualitatively and quantitatively by Blood agar plate method. Tnthis method fabric samples were cut from the surgical wears made fkom 100% bamboo fibre (newly developed) and the surgical wears made fiom 100% cotton (regularly used by hospital) which were already exposed to surgical conditions. These samples were placed in plates with k s h l y prepared blood agar medium, and incubated at 37°C for 24 hrs. The qualitative assessment of bacterial growth was done based on the bacterial colonies developed after 24 hrs. ’Ihe quantitative assessment was carried aut simultaneously by taking the 1” X 1” fabric samples cut from the surgical wears made from 100% bamboo fibre and 100% cotton which were exposed to the surgical conditions in the hospital and immersing them separately in 10 ml of sterile distilled water and kept in the shaker for 10 min. Then 0.1 mi of water taken h m each suspension, was spread plated on the blood agar medium separately and the number bacterial colonies grown after 24 hrs. incubation at 37°C was estimated by counting the number of colony forming units. The bacterial assessment was also done qualitatively by Turbidity method in which the 1” X 1” fabric
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samples cut from the surgical wears made from 100% bamboo fibre and 100% cotton d i c h were exposed to surgical conditions in the hospital were taken and immersed separately in test tubes containing 10 ml nutrient broth which was inoculated with Staphylococcus aureus and incubated for 24 hrs at 37°C. The test tubes were observed for bacterial growth based on the turbidity created in the brcrh. The results were analysed and conclusions were drawn.
RESULTS AND DISCUSSIONS Physical characteristicsof the yarns The comparison of the physical characteristics of the yarns made of 100% bamboo fibre and bamboo fibre I cotton blends are given in Table 1. Table 1
Characteristic Tenacity (RKm) Breaking Elongation (YO) Um % Thin placed km Thick placed km N e d km
Physical characteristicsof the yams Blend Proportion Bamboo: Bamboo: Cotton Cotton 70:30 (%) 60:40 (%) 12.06 12.62
Bamboo: Cotton 5050 (%) 10.68
13.34
BalThO: Cotton 80:20 (Yo) 12.33
14.87
9.65
8.09
8.08
5.18
13.74 78
10.95 3
10.95 4
10.92 5
11.93 34
22 1
26
21
18
75
442
58
61
48
87
Bamboo 100 Yo
Table 1 shows that the yarn made fiom 100% bamboo fibre possesses higher tenacity and much higher elongation % when compared to the yams made from bamboo I cotton blends. But it is found to be highly uneven and having very high level of imperfections when compared to blended yarns.
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Mechanical Characteristics of fabriar made of 100% bamboo fibres and bamboo fibdcotton blends The comparison of the mechanical characteristicsof the single jersy fabrics made of 100% bamboo fibre and bamboo fibre / cotton blends are given in Table 2. Table 2 Mechanical Characteristics ofFabrics Characteristics
Abrasion resistance ( %weight loss) Pilling Resistance grade Bursting Strength (lbdinche.?) Wash fastness Change in shade -grade Staining on Cotton - grade Water Repellency Spray Rating
Test Method
D 4966 / 1998
Bamboo 100%
2.34
AATCC 22,2005
Bamboo: Cotton 60:40
Bamboo: Cotton
(%)
(%)
(%)
(YO)
2.87
5050
4.04
4.40
3
3
4
77.7
75.6
74.2
56
4
4
4
4
4
4
4
4
4
4
0
0
0
0
3
81.1
1975
AATCC 6lA, 2003
Bamboo: Cotton 70:30
3.85
IS 10971/ 1984
IS19661
Bamboo: Cotton 80:20
Abrasion resistance
From Table 2 it is evident that the fabric made fkom 100% bamboo fibres is more resistant to abrasion when compared to the ones made h m bamboo fibdcotton blends and the abrasion resistance decreaseswith the increase in cotton content. Pilling resistance
It could be seen in Table 2, that the hbric made fiom 100% bamboo fibres are more prone to pilling when compared to the fabrics made from bamboo fibrehotton blends and as the percentage of cotton in the blend increases the pilling resistance also increases.
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Bursting strength
From Table 2 it could be understood that the fabric made h m 100% bamboo fibres has higher bursting strength when compared to bamboo fibrehotton blended fabrics and t k increase in cotton percentage in the blendsreduces the bursting strength of the fabric. Wettability
The values of spray rating as given in Table 2, for the fabrics made from 100% bamboo fibre as well as the bamboo fibre'cotton blends show that they possess good absorption characteristic,which is evident fiom their wetting behaviour. Washingfastness
It could be seen from Table 2 that the fabrics made from 100% bamboo fibres and also bamboo fibrelcotton blends possess good colour fastness to washing and staining on cotton.
Anti bacterial characteristics The anti bacterial characteristics of the fabrics made from 100% bamboo fibre and bamboo fibrekotton blends as evaluated by parallel streak method and the qualitative and quantitative assessment of bacterial growth in the 100% bamboo fibre material (newly developed) and the in cotton material (regularly used by the hospital) which were exposed to surgical conditions by blood agar plate method and the assessment by Turbidity method are given as below. Evaluation by parallel streak method
Anti bacterial behaviour of the fabric samples made from 100% bamboo fibres and bamboo fibre I cotton blends inoculated with Staphylococcusaureus after 24 hrs. incubation at 37°C following parallel streak method is shown in the form of photographs in Figs. 1,2,3,4, & 5.
Fig. 1 Bacterial growth in the fabric made h m 100% bamboo fibre
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Fig. 2
Bacterial growth in fabric made from 80:20 bamboo fibre : cotton blend
Fig. 3 Bacterial growth in fabric made h m 70:30 bamboo fibre :cotton blend
Fig. 4 Bacterial growth in fabric made from 60:40 bamboo fibre : cotton blend
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Fig. 5 Bacterial growth in hbric made &om 50:50 bamboo fibre :cotton blend From Figures 1,2,3,4 & 5 it could be seen that the 100% bamboo fibre fabric is able to inhibit the bacterial growth to a greater extent when compared to the bamboo fibrehotton blended fabrics and it could be seen h m Fig.5 that the 5050 bamboo fibre : cotton blend inhibiting bacterial growth to the lowest extent Qualitative and quantitative assessment by blood agar plate method
The bacterial growth in the blood agar plates for 100% bamboo fibre material (newly developed) as well as 100% cotton material (regularly used by the hospital) is depicted in the form of photographs in Figs. 6 & 7.
Fig. 6 Bacterial growth in surgical wears made from 100% bamboo fibre and 100% cotton From Fig.6 it could be seen that the blood plate with bamboo fibre material exhibits less bacterial colonies when compared to the blood agar plate with cotton material. It is to be noted that both the materials wcre exposed to the same surgical conditions.
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Fibre
Fibre
Fig 7 Bacterial colony forming units in surgical wears made h m 1OOOh bamboo fibre and 100% cotton From Fig. 7 the number of bacterial colonies developed after 24 hrs incubation in blood agar medium could be easily counted as they are visible clearly. On counting, it was found out that bamboo fibre material contained 32 X Id colony forming units of bacteria, whereas in case of cotton material it was 127 X Id colony forming units of bacteria. From the results of the blood agar plate method, it is very clear that the material made of bamboo fibres is able to inhibit the growth of pathogenic bacteria effectively. Evaluation by turbidity method
The photograph showing the test tubes containingnutrient broth in which the samples of 100% bamboo fibre material and 100% cotton material (which were exposed to actual surgical conditions) were immersed and inoculated with Staphylococcus aureus and incubated for 24 hrs at 37" C, is shown in Fig.8.
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1OO??Cotton Fibre
Fibre
Fig. 8 Nutrient broths with 100% bamboo fibre material and 100% cotton material It could be seen from Fig.8 that in the test tube with cotton material sample, the nutrient broth is turbid. But in the test tube with bamboo material immersionthe nutrient broth is clear. The development of turbidity in the nutrient broth is a clear indication of bacterial growth. Staying clear after 24 hrs incubation, the bamboo material has proved its anti bacterial characteristic.
CONCLUSIONS Following conclusions are drawn from this research work. 0 The yarn made from 100% bamboo fibre is very uneven with higher imperfection level when comparedto the yarns made of bamboo fibre I cotton blends. 0 The single jersey fabric made fbm 100% bamboo fibre possesses higher abrasion resistance, lower pilling resistance, higher bursting strength when compared to the single jersey fabrics made h m bamboo fibre I cotton blends. The increase in cotton content reduces the bursting strength and the abrasion resistance and increases the pilling resistance . 0 The single jersey fabric made from lOO?h bamboo fibre possess good wettability and washing fastness characteristics which are at par with the fabrics made of bamboo fabric 1cotton blends. 0 The knitted fabric made from 100% bamboo fibre exhibits good anti bacterial characteristics. It is found to be effective in inhibiting bacterial growth, when compared to
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the fabrics made h m bamboo fibre I cotton blends. In fact the presence of cotton in the blend reduces the effectivenessto inhibit bacteria. 0 This research work has confumed the antibacterial characteristic of bamboo fibre and thrown light on its effective application in surgical wears. Aclmowledgementa
The author is tbadchl to the undergraduate Apparel & Fashion Technology students of PSG College of Technology M/s. Fatima K. Moaiyadi, Joy Olivia Isaiah, Kerry Renaux, Nivas.K.M. and Pavithra.J. for carrying out the experiments. The author thanks the management of M/s. Kannapiran Mills Ltd., Coimbatore and their R&D officer h4r.P.Madava Murthi for producing the yam samples from bamboo fibre and cotton blends and providing the same for the research work The author is thankful to the Management of PSG Hospitals, Coimbatom for their valuable help in testing the samples in actual surgical conditions. The author thanks Dr.MAnantha Subramanian, AsstProfessor, Dept. of B b Technology, PSG College of Technology for the useful discussions on micro biological aspects of the research work
REFERENCES 1 www.bambrotex.com 2 www.tenbro.com
3 www.bamboofabricstore.com 4 ASTM International book of Standards, 2004
5 AATCC Technical Manual, 2001 6 Indian Standards Book, 1975
180 0 Woodhead Publishing Limited, 2010
THERMAL CHARACTERIZATION AND MECHANICAL PROPERTIES OF PLA YARNS A M Manich', D Cayuela2,M Marti', R M Sam'' and M Ussman' 'CSIC - Spanish Council for Scientific Research, Barcelona, Spain 21NTEXTER, UPC - Technical University of Catalonia, Terrassa, Spain 'UBI - Universidade da Beira Interior, CovilhB, Portugal
ABSTRACT Commercially available PLA plain weave fabric of 245.26 g/ma, 0.85 mm in thickness formed by 29.5 warp yarnshm of 41.6 tex and 14 weft yarndcm of 92 tex. After being washed with non-ionic surfactant and rinsed, dry and wet samples were subjected to thermal treatment a t 1215OC during 3 hours to induce some kind of recrystallisation in order to modify their mechanical properties. Another sample was subjected to plasma treatment in a radiohquency unit (13.56 MHz) in vacuum conditions (0.05 mbar) before introduction of air as plasma generator. Treatment was performed a t 1 mbar for 6 minutes a t 100 W. All samples were immersed in phosphate buffer solution (pH=7.4) for a week at 40°C in order to obtain different PLA treated samples. Thermal charaeterization was done by DSC and Thermo Mechanical Analyzer which gave values of thermal transition and relative crystallinity of the samples. The TMA gave information about glass transition and Dilatometric transitions due to temperature. Mechanical properties were measured by testing mechanical properties in single strand, knotted and laced form, and also elasticity and relaxation behaviour of yarns were characterized by measuring the immediate elastic recovery, the delayed recovery and the permanent deformation of yarns. Stress relaxation was modelled by the application of three Maxwell units in parallel to evaluate the high-rate, the medium rate and the low rate relaxed stress of yarns. Lastly mechanical properties of fabrics were measured by the bursting strength and the bagginess of fabric after being subjected to cyclic multiaxial strain test. Performed tests gave important information to bandaging and pressure medical devices.
INTRODUCTION (Polylactic acid) PLA is linear aliphatic thermoplastic polyester derived from 100% annually renewable crops. Most initial uses were limited to biomedical applications such as sutures and drug delivery systems due to availability and cost of manufacture. PLA fabrics can be used to cultivate different human organs. The process involves culturing and growing living cells, taken from human organs, on a textile scaffold, to the desired 2-dimensional andor 3 - d h e n s i o d shapes. PLA can be used in this application because it is a biodegradable and resorbable fibre. During the process of degradation, fibrous connective tissues replace the degrading implant. The kcy advantage is that no further surgery is required to remove the products since they slowly degrade in the body without any side effects [l]. When designing PLA tissue engineering scaffolds, the length of time it takes for the polymer to degrade, must be investigated [2]. The objective of this work is to apply different characterization techniques in order to test their sensitiveness in relation with the degradation level of the PLA. Thermal, thermomecanical and mechanical testing procedures have been applied to monitor the variation induced on a commercially 0 Woodhead Publishing Limited, 201 0 181
available PLA fabric which has been subjected to dry heat high tempera& method and degradation in phosphate buffer solution pH 7.4.
sterilisation
MATERLAL
PLA plain weave fabric sample of 245.25 g/mz, 0.85 nun in thickness formed by 29.5 warp y d c m of 41.5 tex and 14 weft yamslcm of 92 tex were used. The sample were washed using non-ionic surfactant, rinsed and then dried in standard atmosphere. Treatmenta Sferilisation was made using the dry heat high temperature method. Dry and wet samples were subjected at 125OC during 3 hours to attain their complete sterilisation. The sterilisation process can induce some kind of annealing, melting and recrystallisation modifjmg their fine structure. Surface modification. A washed sample was subjected to plasma treatment in a radiofrequency unit (13.56 MHz) in vacuum conditions (0.05 mbar) before introduction of air as plasma generator. Treatment was performed at 1 mbar for 5 minutes at 100 W. Initial Degradation. All samples were immersed in phosphate buffer solution (pH=7.4) for a week at 37°C in order to obtain an initial estimation of the degradability of the washed, sterilised and plasma-treated samples. Strong Degradation. After the estimation of the initial degradation, the samples were subjected to an accelerated degradation process by immersion in phosphate buffer solution (pH=7.4) at 5OoCduring four weeks. The identification of the samples according to the treatments were subjected to the following: 0
Reference
Washing
Sterilisation
Surface Initial Strong modification degradation degradation
dry sample wet sample
X
0-OR 1-wD 2-STd 3-STw
X
4-SL 5-PT
X
11-WDSd 2 1-STdsd 3 1-STWSd 41-SLsd 51-PTd
X X
X
X X
X
X X
X
X
dry sample
X
X
X
wet sample
X
X
X
X
X
X
X X -
X
METHODS
Thermal and Thennomechanical method8 DSC: Trials have been performed in a Mettler-Toledo DSC 823 unit using 40 p1 sealed pans containing approximately 6 mg of PLA with the following conditions: Initial 182 0 Woodhead Publishing Limited, 2010
temperature 30°C, final temperature 2OO0C, heating rate 10°C/min, and purging gas nitrogen 50mI/min. T M : For Thermomechanical analysis a Mettler-Toledo T W S D T A 840 was used. The substrates were prepared in a special support for filmdfabrics cutting rectangular samples in warp and weft direction of 1575x6 mm being tested with gauge length of 10 mm. Tests were performed under the following conditions: Initial temperature 25"C, final temperature165"C, heating rate 2"C/min, dynamic loading between 0.1 and 0.2 N at 1/12 Hz,purging gas nitrogen 35 ml/min.
Mechanical propertics Yarn Tensile properties: Specimens with gauge length of 100 mm were tested after being conditioned in a standard atmosphere for 48 hours. Breaking load [N] and strain [%I in single strand knotted and laced form were determined on yams subjected to tensile testing at 60%/min accordingto the ASTM D 2 101 Standard [3].
Yarn Stress Relaxation test: Five specimens with gauge length of 100 mm were tested after being conditioned in a standard atmosphere for 48 hours. Specimens were subjected to 25% at 60%/min in the MT-LQ dynamometer. The average of the initial stress q and stresses at 1,2,3,4, 5,6,7, 8, 10, 12, 14, 16, 18,20,25,30,35,40,45,50, 60,70,80,100,120, 140,160 and 180 seconds were recorded. Fitting the Stress Relaxation Model: The relaxation times were pre-selected TO = 1 s, z1= 10 s and z2 = 100 s to differ between them in one order of magnitude and to be placed into the length of time of the stress-relaxationtest according to Vitkauskas's conditions [4].Based on the pre-selected relaxation times, the multiple regression analysis [5, 61 was used to obtain the estimators of high-rate 00, medium-rate ( ~ 1 , low-rate 0 2 relaxed stresses and ofthe non-relaxed or final stress. The determination coefficients of the all fitted multiple regression equations were approximately of 99.96%. All the terms were highly si&icant, which explains that relaxation is produced as a consequence of three relaxation processes occurring in parallel (cfi. Figure 1). Values of reduced stress obtained by dividing the stress observed at time t by the initial stress oi expressed in % were used.
Figure 1: a) Maxwell unit, b) Generalized Maxwell model to account for the stress relaxation of PLA yarns 0 Woodhead Publishing Limited, 201 0 183
Yarn Elasticity: The elastic properties of the yams using an Instron 5500R dynamometer and applying the ASTM standard with small modifications [7]. Two deformation cycle testing were performed defined by the maximum load Qmax of 5 N at 30N/min which the specimens 100 mm in length are subjected according to the procedure schematically presented in Figure 2. The waiting time between the first and the second cycle was 3 minutes. The trigger load at which the immediate elastic recovery, the delayed recovery and the permanent set were measured was 5% of the maximum load Qmax. Fabric Bursting strength: A h4T-LQ Stable Micro Systems dynamometer equipped with a clamping device for securing the fabric sample and a probe for producing fabric bursting has been used. A circular area of fabric is clamped around its circumference. A circular area of 25 mm i 0.1 mm diameter must be exposed for testing. The clamping device should be positioned centrally above the probe. A cylindrical probe comprised of steel with a hemispherical test head of diameter 9 mm 0.1 mm (the hemispherical head should have a radius of curvature of 20 mm) and a length suitable to allow ease of testing up to fabric breakage. The zero position for this test shall be taken as the point where the probe contacts the fabric resulting in a force of 0.25 N. The probe shall move from zero position towards the fabric surface at a speed of 1 mm/s until fabric breakage is produced. The maximum of the stress-strain curve allows determining the breaking strength and the breaking deformation of the fabric. Normally four samples are tested and the mean breaking strength and deformation are given.
f
Figure 2: Two cycle test at a maximum fixed load for the determination of the elasticity and plasticity of PLA yarns: Straining at the maximum load S1, Immediate Elastic Recovery ER, Delayed Recovery DR and Permanent Set PS. The trigger load was 5% of Qmax.
Relaxation, Creep and Fabric Bagginess: A probe is pressed against a sample disk, which is firmly held around its circumference, until a load equal to 75 N is applied. The deformation achieved at this force is held for 10 seconds and then the load is removed. This process is repeated for 5 cycles. Afterwards, the sample is allowed to relax for 60 184 0 Woodhead Publishing Limited, 2010
seconds and the residual deformation in mm (bagginess index) is measured. The following graphs of force versus time and displacement versus time are obtained (See Figure 3 a and b) [8,9]. The method was origmally made up to measure the bagginess index; this is the residual deformation of a sample after cyclic multi-axial strain. Moreover, it has been proved to be also useful to study creep, or time dependent change in strain following a change in stress, and stress-relaxationor decreasing of stress along time when applying a certain strain. As it can be observed in Figure 3 a, it is possible to quantify the phenomenon of stress-relaxation within each cycle. The value of force is determined 1, 2,4, 6 and 8 seconds after the application of an initial load of 75 N in each cycle. The graphical representation of these values versus the ln(time(s)) leads to the adjustment of a linear equation whose slope is the stress-relaxation index. On the other hand, the phenomenon of creep can be quantified by determining the value of displacement in each cycle. The graphical representation of these five values versus ln(cyc1e nr.) allows the adjustment of a linear equation whose slope is the creep index [9] (Fig 3 b). This method also provides a simple and quick way to measure the fabric bagginess index.
RESULTS DSC: Generally speaking, sterilisation of dry and wet samples increases the glass transition temperature of the PLA fibre from 66°C to 74°C approximately, and degradation additionally increases the glass transition in 2OC.
Figure 3: a) Graph Force vs Time and b) Graph Displacement vs Time obtained in the bagginess/creep/stress-relaxation 0 Woodhead Publishing Limited, 2010 185
The melting endotherm shows two peaks with temperature peaks at about 162.3"C and 1695°C. Washing,sterilisation and degrading do not affect peak temperatures, although degradation decreases the second peak temperature in 1°C approximately the wet sterilised sample decreases by more than 2.5"C. Strong degradation induces relevant differences in the relative height of the two peaks. It increases the height of the 1' peak at expenses of the second one being the highest ones those of the sterilised samples. The Plasma treated sample showed scarce differences between the melting peak heights.
TUA: Temperature change can lead a material through Merent transitional phases. These can cause the specimen to expand, contract, to melt and recrystallise or to go through a major structural changes [lo, 113. Before meting PLA fibre begins to sbrink. The onset temperature of retraction was near 160°C for the non degraded samples and 154°C for the strongly degraded ones. The lowest onset temperature of retraction was that of the strong degraded plasma treated samples. The melting temperature measured at the TMA showed very highly significant dif€erences between non degraded and degraded PLA samples. Tm of the original samples was near 161°C approximately, while Tm of the degraded ones was approximately of 153°C. This confirms that degradation affect the more perfect crystals with higher melting temperatures favouring the formation of crystals of lower size and perfection. Yarn tensile properties: No big differences were observed between single strand, knotted and laced f o m The mean values in breaking strength and deformation in single strand of warp and weft samples will be reported in Table 1. Table 1. Breaking strength and strain of single PLA yams Reference Breakstrength Break.strain Reference Breakstrength Breakstrain 0-OR 6.75 N 35.47% 1-wD 6.50 N 34.00% 11-WDsd 2-STd 6.56 N 35.26% 21-STdsd 4.03 N 14.94% 3-STw 6.07 N 33.15% 31-STwsd 3.88 N 14.44% 4-SL 6.35 N 33.25% 41-SLsd 3.30 N 8.74% 5-PT 6.01 N 29.17% 5 1 -PTsd 3.58 N 10.61% Yarn mess relaxaiion test: After strong degradation no relaxation tests straining at 25% were possible to be performed because strong degradation decreases breaking strain under 25%. The mean values in the initial load at 25% straining, and the high-rate, medium-rate, low-rate and final non-relaxed load in % of the initial load of warp and weft Samples will be reported in Table 2. Table 2. Yam relaxation test. High-, medium-, low-rate relaxed and non-relaxed load Reference
Initial Load
High-rate
25% straining relaxed load
0-OR 1 -wD 2-STd 3-STw 4-SL 5-PT
4.22 N 4.24 N 4.23 N 4.30 N 4.11 N 4.21 N
14.12% 14.14% 13.47% 13.38% 13.39% 14.46%
Medium-rate relaxed load 11.06% 10.86% 10.73% 10.37% 10.94% 11.36%
Low-rate Final nonrelaxed load relaxed load 12.79% 61.92% 12.57% 62.36% 11.97% 63.73% 12.29% 63.86% 12.48% 62.60% 12.45% 61.71%
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Yarn elasticity: After strong degradation no elasticity tests were possible to be performed because the strong degradation decreases breaking load under 5 N. The mean values of the initial deformation at 5 N and the immediate elasticity, the delayed elasticity and the permanent set in % of warp and weft samples are reported in Table 3. Fabric Bursting strength, relaxation, creep and bagginess: Results of bursting strength and deformation, and results of relaxation index, creep index and bagginess after 5 cycles of deformation at 75 N made on the original and the washed samples and on the strongly degraded samples are given in Table 4. DISCUSSIONAND CONCLUSIONS The diffmntial scanning calorimetry allows us to identify variations in glass transition and melting of PLA. It has been proved that sterilisation increases glass transition temperature fiom 66 to 74°C and degradation additionally increases Tg in 2°C. Although the two peak melting endotherm temperatures were 162.3 and 169.5OC treatments influence the height of peak. The strong degradation increases the heigh of the low temperature peak at expenses of the high temperature peak, especially in the case of sterilised samples. It means that sterilisation degrades the high size and more perfect crystals contributing to the formation of low size less perfect crystals with lower melting temperature. Table 3. Elastic characteristics and permanent set of yarns strained at 5 N Reference 0-OR 1-wD 2-STd 3-STw 4-SL 5-PT
Initial strain at 5N 19.11 % 18.47 % 20.11 Yo 19.44 % 19.60 % 18.59 %
Immediate Elasticity 20.91 % 21.67 % 22.82 Yo 22.23 % 21.35 Yo 21.80 %
Delayed Elasticity 21.26 % 21.49 % 23.88 Yo 23.28 Yo 22.28 Yo 23.31 Yo
Permanent set 57.83 % 56.84 % 53.30 Yo 54.49 Yo 56.38 % 54.89 %
Table 4. Fabric bursting strength and strain and relaxation, creep and bagginess after five deformation cycles at 75 N Reference 0-OR 1 -wD 2 1 -STdsd 31-STw~d 41-SLSd 5 1-PTd
Bursting strength 358.0 N 348.0 N 301.3 N 265.0 N 240.9 N 237.2 N
Bursting deformation 8.89 mm 8.53 mm 8.22 mm 7.62 mm 7.43 mm 7.33 mm
Relaxation index 2.289 2.223 2.057 2.522 2.286 2.486
Creep index 0.219 0.216 0.207 0.212 0.219 0.269
Bagginess index 2.109mm 2.686mm 2.516mm 2.551 mm 2.807 mm 3.310rnm
The Thennomechanical analysis reveals the same influence. The onset temperature of retraction for non degraded samples that is observed at 160"C, is decreased by degradation in 6°C which confirms that degradation affect the more perfect crystals with higher melting temperatures favouring the formation of crystals of lower size and 0 Woodhead Publishing Limited, 201 0 187
perfection. The same effect can be observed about the melting temperature determined at the TMA. Surface modified samples by plasma showed the lowest temperatures of shrinkage and melting. As regards to the yam tensile properties the breaking strength and strain of strongly degraded yams decreased significantly. Sterilisation favours the resistance of the PLA against degradation and the surface modified PLA fibre by plasma seems to be more sensitive to the initial degradation than to the strong degradation of the fibre. In relation with the stress relaxation and the elasticity of yarns it was not possible to compare the results with the strong degraded yarns because. highly degraded yams cannot withstand the experimental conditions of the non-degraded yams. Nevertheless the effects of the sterilisation on those characteristicsof the PLA yarns were observed: Sterilised yams showed lower relaxation and higher elasticity than that of the non sterilised ones. As regards with the fabric characteristics, bursting strength and deformation shows the effect of the strong degradation on these characteristics, and the high level of bagginess and creep of the strong degraded fabrics along five cycles of deformation were specially sigmficant. Summarising, themnomechanical analysis and mechanical testing of yams and fabrics were the more sensitive methods to monitor the degradation of the PLA fabrics when subjected to a degradation process into a phosphate buffer solution pH 7.4.
ACKNOWLEDGEMENTS Authors are indebted to the Spanish Project MAT2004-04981-C03-03 for its financial contribution. They recognise the contribution of the GRICESKSIC 2005PT005 1 Project helping the elaboration of the paper, and they are also indebted to Ms. R Mateu, A Lopez and C Martinez for its contributionto the experimental work.
REFERENCES 1 R S Blackbum, Biodegradable and sustainable Jibres, Woodhead Publishing Ltd. And CRC Press, Cambridge, pp 191-219,2005 S C Anand, J F Kennedy, M Miraftab and S Rajendran, Medical textiles and biomaterialsfor healthcare, Woodhead Publishing Ltd. And CRC Press, Cambridge, pp 58-66,2006
2
3 Standard Test Method ASTM D 2101 ‘Tensile properties of single man-made textile fibres taken from yarns and tows’, 1979
4 Vitkauskas, ‘Regular discrete relaxation time spectrum of textiles’, Medziagotyra (J Muter Sci), 1996 2 65-71 5 STATGRAPHICS Plus Statistical Software. Manugistics, Inc. 21 15 East Jefferson Street, Rockville, Maryland 20852, USA
6 N R Draper and H Smith, Applied Regression Analysis, 2”dEdition, J Wiley k Sons, New York, 1981 188 0 Woodhead Publishing Limited, 2010
7 Standard Test Method ASTM D 1774-79 ‘Elastic Properties of Textile Fibers’, 1979 8 A M Manich, T Bosch and A J Long, ‘Measurement of creep, relaxation and bagginess indexes of leather’, JSoc L a t h Tech Chem, 2000 84 133-136 9 A M Manich, M Marti, R M S a d , M D de Castellar and J Carvalho, ‘Effect of finishing on woven fabric structure and compressional and cyclic multiaxial strain properties”, Text Res J, 2006 76 86-93 10 J W S Hearle, Polymers and their Properties. Vol I :Fundamentals of Structure and Mechanics, Ellis Horwood Ltd. Publishers, Chichester, 1982 11 S K Mukhopadhyay,Advances in Fibre Science, The Textile Institute, 1992
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PART 111 WOUND CARE MATERIALS
WOUND CAREMATERIALS AN OVERVIEW M. M i d b Institute for Materials Research and Innovation, The University of Bolton, Bolton, UK Wounds resulting from injury, disease or accidents need external intervention to help them repair and resume their normal bodily functions. Ideally, the repairs need to be neat and replicate the undamaged skin or organs as closely as possible. Hence any material or dressing that could potentially assist the repair process whilst providing suf€icient protection against possible bacteria spread in and out of the wound area is classified as “Woundcare Material”. Types and form of woundcare materials used are extensive and include a wide range of ~ t u r a and l synthetic materials. The available woundcare literature(*233) adequately covers the entire range of these products and their specific attributes, therefore this idormation will not be regurgitated in this short review. A concise reference to most woundcare materials has been made by the author in “Medical textiles and biomaterials for healthcare” Part fi4) and interested readers are referred to it. This review will instead concentrate on the latest research and developments where new and existing materials are increasingly amalgamated with intelligent and proactive natural andor manmade ingredients andor devices to achieve better and faster results. Over five million people each year in the UK suffer fiom various kinds of wounds that require treatment. As the age profile of the population increases, chronic or hard to heal wounds resulting from diabetes, pressure induced wounds, cancer and leg ulcers are becoming by far the most dominant and potentially most expensive types of wounds to treat. The cost to the NHS of caring for patients with a chronic wound is conservatively estimated at €2.3bn-3. lbn per year (at 2005-2006 .UK represents approximately 4% of the global costs hence the total worldwide expenditure on chronic wound treatments is in the region of E57.5-75 billion. It is therefore no surprise to see an explosion of new materials and products entering this market. Given this scenario and the resulting intense competition, it is no longer acceptable for a wound dressing to be; merely non-toxic, biocompatible, haemostatic and operate within the constraints of universally accepted “moist healing” theory. Dressings are today expected to be much more proactive and responsive to; the healing process, time constraints and scar free outcomes. WOUNDS NATURAL HEALING MECHANISMS VERSUS WOUND CARE MATERIALS
When an injury occurs, the body’s defence system is immediately mobilised starting with coagulation. This is brought about by migration of the platelets or the cells prcsent in the blood to the affected site and their subsequent exposure to fibrin, a protein responsible for causing haematosis. Growth factors are released from the platelets and the healing process is initiated from this very early stage. If the injury or the cut is deep and more serious, this leads to inflammation allowing migration of white blood cells to the affected area where they fight foreign matters whilst bringing along additional growth factors. Next, the wound undergoes proliferative phase where collagen deposition and granulation occurs followed by epithelisation where epithelial cells stretch across the wound bed and contraction begins. New blood vessels are finally formed and remodelling is initiated. This highly simplified trend of events leading to total recovery of the wound may not necessarily occur in the order described and 0 Woodhead Publishing Limited, 2010 193
overlap at various stages, but it’s a generalisaiion of the complex steps involved in the healing process. To be effective as a dressing, the wound dressing material needs to; stimulate, promote, and accelerate the above processes in some coordinated fashion so as to achieve medically better and aesthetically more acceptable results with minimal costs, where possible. Growth factors are fundamental to the healing process; from generating new epidermal skin to formation of granulation tissues and developing new blood vessels. Growth factors are classified according to their function and their availability at various stages of the healing process and it is their carefully orchestrated set of actions that leads to regeneration of the missing parts and therefore total recovery. A hard to heal or a chronic wound is deficient in these crucial growth factors essential for the healing process. Externally introduced growth factors under moist environment is one way of assisting this process, and this is where much research is currently in progress. Regranex(@produced by Johnson & Johnson is one such product that was first approved by FDA in 1998 for treating chronic diabetic neuropathic ulcers. It is made Erom genetically engineered platelet-derived growth factor and is applid as a topical gel. It actively stimulates the body to grow new tissues and aids the healing process. Clinical results have shown much improved recovery rates in diabetic patients sulTering Erom neuropathic foot ulcers. Hyaluronic acid has been recognised as an integral component of the extracellular matrix in the skin and underlying tissues influencing wound inflammation, cell migration, angiogenesis, re-epithelialization and scar development. HYM7), a biomaterial fibrdfleece produced by Advanced Biopolymers is based on esterfication of hyaluronic acid with different alcohols. It is used as a scaffolding base as well as dressings for diabetes and skin burn sufferers. This product is not only highly biocompatible but it is also biodegradable with proven ability to enhance tissue repair. Dressings containing fibroblast growth factors encapsulated in micro-spheres with the intention of prolonging growth factor release is another innovative approach to systematic tissue regeneration and hence healing. Tests on animals using these types of dressings have shown reduction in wound area and reasonable tissue/skin regeneration(’). Using genetically engineered human collagen, a new dressing that enables faster and improved healing has also been introduced. A more practical method however, includes mixing collagen with cellulose in the form of sheets or films.Known as Active Matrix Dressing, Promogran(’) produced by Johnson & Johnson takes advantage of the combined properties. Upon exposure to exudates, the active matrix forms a gel which, apparently, quells agents hostile to the healing within the wound and therefore speeds up recovery. Successful outcomes have been reported for treating pressure sores, leg ulcers and other chronic wounds. Another fairly recent technique of treating chronic wounds is known as VAC or Vacuum-assisted closure(’o).This method takes advantage of starving bacteria to death by cutting off the supply of air needed for its survival. This is usually carried out by inserting a foam dressing into the wound area armed with a drainage tube. The opposite end of the tube is attached to a vacuum pump whose action eventually kills the aerobic bacteria The vacuum action also removes necrotic and slough materials allowing the wound to close. Improved microcirculation leads to greater level of oxygen access to the tissues and hence recovery. This method of therapy can be highly effective if not very convenient. It is however, relatively expensive. 194 0 Woodhead Publishing Limited, 2010
Since the resurgence of old and traditional treatments where silver, honey and lava are prime examples, a variety of other techniques based on greater understanding of the body's physiological reaction to cuts and wounds have been developed with considerable successes. Electrical stimulation for instance, is a technique by which body's electrical activities are mimicked when an injury is received. Such simulations promote attraction of repair cells; alter permeability of cell membranes and influence cell structuring and secretion which ultimately leads to better healing. POSiFECT"" from Biofisica is a newly introduced bioelectric wound care dressing that delivers the current through a pad that sits on the wound face with an independent power source. Clinical trials on non-healing wounds using these products have paved the grounds for thcir wider availability. Improvement in blood circulation induced by high sound frequency is another method by which cells responsible for wound healing are believed to be stimulated during inflammatory and proliferative stages. These frequencies are generated in moisthydrogel based dressings in the wound area. Similarly, Whirlpool therapy(") is another method by which blood circulation and hence availability of oxygen to the wound area is increased leading to better healing. This technique however, is not suitable for wounds where excessive blood is present i.e. venous leg ulcers. The efficacy of both these methods is subject of further investigations. More recent methods of relieving pain and enhancing healing has included low-level laser therapy (LLLT) where red and near infrared light in the frequency range from 600 nm to 1000 nm produced by laser or light-emittingdiodes (LED) have been shown to be These research trials are ongoing. effective in treating chronic Based on the selection of examples referred to in this short overview, it is clearly evident that research in woundcare area (material or otherwise) is an ongoing process and will continue to develop as healing parameters and regeneration mechanisms are better understood. Based on these understandings, new materials will emerge that would combine natural and manmade materials more effectively to achieve better outcomes.
REVIEW OF PAPERS ON WOUND CARE MATERIALS Nanofibres intended for specialised applications are fast replacing micro-fibres given their enormous aspect ratio (widthflength) and high surface area. Their flexibility and conformation to particular shapes where seams, stitches and inconsistenciesare avoided are other reasons for their popularity. Electrospinning is one such technique where charged polymeric nanofibres are generated from application of high voltage and subsequently drawn across by electric field. The plenary paper submitted under this title reports on production of antibiotic loaded electrospun polyester fibres and examines the release mechanics of the antibiotic content and their potential effectiveness in killing bacteria over time. Odour from badly infected wounds causes extreme distress to the patients and anyone who comes in contact with them. The repulsive smells associated to these types of wounds are due to the volatile agents created by concoction of bacteridchemical byproducts undergoing metabolic processes. Inefficiency in performance criteria of existing products in containing these undesirable odours has focused researchers' attention to new and possibly novel methods of tackling the problem. The first paper in this series evaluates a selection of commercially available dressings containing activated charcoal for their acclaimed properties using a dedicated instrument and foresees the advent of better and more effective products through continuing research where identified problems associated to use of activated charcoal would be eliminated. 0 Woodhead Publishing Limited, 201 0 195
Since 1995, on average, over 35 new dressings have been added to the Drug Tariff every year, to the extent where today there exists over 400 brands of wound dressings each claiming unique or specific properties. Nurses and clinicians who are in the forefront of this influx are increasingly confused and on occasions are in disagreements with one another as to what dressing to choose and prescribe without hdermining patients’ welfare, safety and treatment needs whilst working within budgetary constraints of hospitals and the health service. The next paper highlights the need for a unified and a regulated approach based on collectivejudgement of panel of experts and its amalgamation with an expert system that would be available nationally. The paper reports on an initial survey involving primary care trust nurses and demonstrate the working principles of such an expert system. Targeted delivery of drugs, vitamins and other ingredients via encapsulation and hence localised dispensation is highly efficient, cost effective and neat way of treatingkhieving desired results. However, matlllfacturing methods, control of microcapsule size/uniformity and microcapsule shellhgredient compatibility are still subject of much research. The third paper in this series investigate the feasibility and effectiveness of microencapsulating cosmetic or medical fragrances such as rosemary oil and limonene in ethyl cellulose by phase separation method and their subsequent application onto cotton fabrics. The work concludes a direct relationship between produced microcapsule size and stirring speeds and confirms successful encapsulation of the fragrances via spectroscopic analysis. Ester bond formations between hydroxyl groups of cotton and that of ethyl cellulose are also verified. With increasing improvements in medical science and subsequent treatment efficiencies, patients’ expectations of general welfare and aftercare treatments have also increased. Today, patients expect to suffer l?om little or no pain, have scar free results following any minor or major surgery and to be as mobile as they possibly can. The fourth paper presented in this chapter acknowledges the need for compression garmentshandages whereby disfigurement and scar formation are prevented in bum injuries in particular, but questions the adequacy and effectiveness of current practices. It then introduces a new pressure monitoring machine which is claimed to have better but limited ability to monitor pressure changes at body/garment interface. Herbal medicine and ointments derived from natural sources have existed from very early history of human civilizations and numerous claims and counter claims are made with regards to their effectiveness. Psyllium husk is one such plant-based material that has traditionally been recommended for alleviation of various aliments including; diarrhoea, haemorrhoids, bladder problems, high blood pressure, cardiovascular disease, cancer, diabetes as well as dietary supplements. The final paper in this chapter reviews various aspects of this species and based on its inherent properties it highhghts its potentials for serious considerationin new areas including biomaterials. REFERENCES 1 A Heenan, Dressings on the drug tariff, World Wide http://www.worldwidewounds.com/l997/july/Heenan/T~.html
Wounds,
2 S Petrulyte, ‘Advanced textile materials and biopolymers in wound management’, Danish Medical Bulletin, Feb 2008 55( 1).
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3 S C Anand, J F Kennedy, M Miraftab and S Rajendran, Medical Textiles and Biomaterials for Healthcare, Woodhead publishing Ltd, Cambridge, CRC Press LLC, Florida, 2006.
4 M Miratlab, Woundcare Materials, an overview, In Medical textiles and biomaterials for healthcure, Woodhead publishing Ltd, Cambridge, (S C h a n d , J F Kennedy, M Miraftab and S Rajendran (eds), Woodhead publishing Ltd, Cambridge, UK ,2006). 5 J Posnett, P J Franks, ‘The burden of chronic wounds in the UK’, Nursing Times, 2008 104(3) 44-45. 6 M Braddock, C J Campbell and D Zuder, ‘Current therapies for wound healing: electrical stimulation, biological therapeutics, and the potential for gene therapy’, International Journal of Dermatology, November 1999 38(11) 808-817. 7 L A Solchaga, J E Dennis, V M Goldberg and A L Caplan, ‘Hyaluronic acid-based polymers as cell carriers for tissue-engineered repair of bone and cartilage’, Journal of Orthopaedic Research, Feb 2005 17(2) 205-213. 8 C A Cochrane, C Shearwood, M Walker, P Bowler and D C Knottenbelt, ‘The application of a fibroblast gel contraction model to assess the cytotoxicity of topical antimicrobial agents’, Wounds, August 2003 issue 8.
9 Clinical Review, ‘A guide to the latest advanced wound care products’, Nursing & Residential Care, February 2006 8(2). 10 S Thomas, An introduction to the use of vacuum assisted closure, World Wide Wounds, May 2001, httr1://www.worldwidewounds.comJ200 1 lmaWThomasNacuumAssisted-Closure.html.
1 1 A Moody and K Baines, ‘Managing a non-healing pilonidal sinus with POSiFECT estimulation’, British journal of community nursing, 2008 12(12) S14, S16, S18 passim.1SSN: 1462-4753. 12 L Angelo Jr, Whirlpool therapy facility and method of treatment, US patent Office, Pat No 4291646, August 1999. 13 J T Hopkins, T A McLoda, J G Seegmiller and G D Baxter, ‘Low-level laser therapy facilitates superficial wound healing in humans: A triple-blind, sham-controlled study’, Journal OfAthletic, July 2004 39 223-229.
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CONTROLLED DRUG RELEASE FROM NANOFIBROUS POLYESTER MATERIALS M J Bide (l), M D Phaneuf (2), T M Phaneuf(2) and P J Brown (3); (1) University of Rhode Island, Kingston, RI USA, (2) BioSurfms, Ashland, MA USA; (3) Clemson University, Clemson, SC USA
ABSTRACT Background Over 13 million medical devices are used annually in the United States, many of them based on fibrous materials, such as simple wound dressings, hernia repair mesh, catheter cuffs and to more prosthetic arterial grafts. All medical devices are prone to complications of infection, unregulated cellular growth, and undesirable blood clotting behavior. Currently available biomaterials do not emulate the dynamic biologic and reparative processes that occur in normal tissue to overcome these complications. Thus, a novel biomaterial for use in a wide range of medical devices to direct or enhance the normal healing processes of native tissue would improve patient morbidity and mortality. Goal
The goal of this study was to synthesize and characterize in vitro novel nanofibrous materials that contained biologically-activeagents such as antimicrobial, antifungal and antiseptic agents. Our hypothesis was that the nanofibrous materials would serve as a "reservoir", slowly releasing the active agents over an extended period of time. We employed electrospinning technology in order to synthesize the nanofibrous polyester materials. A major benefit of this process is that the polyester nanofibem are formed at low temperatures, unlike standard polyester fibers which are extruded as a melt at high temperatures. The low temperature permits the structure of the active compounds to remain intact, thus retaining their biological activity. Additionally, no exogenousbinder agents or polymers are required to incorporate the respective agents. Variation of drug concentration into the bulk polymer solution prior to electrospinning was also examined.
Evaluation of these drug-loaded polyester nanomaterials for drug release via U V M S spectrophotometry and subsequent biologic activity via specific biologic assay was performed for segments subjected to stringent washing conditions. These studies showed that active agent was released for an extended period of time (days to weeks) while maintaining activity upon release as compared to control nanofibrous polyester, which had no activity at any of the time periods examined. Activity of these surfaces was also controlled by the initial concentration loaded into the bulk polymer as indicated by our release and activity studies.
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Conclusions This study demonstrates that biologically-activeagents can be individually incorporated into a nanofibrous polyester material. Additionally, these compounds are slowly released over an extended washing period. Lastly, these nanofibrous surfaces can maintain localized biological activity due to the drug elution fiom the nanofibrous material.
INTRODUCTION As recognized by the long history of this conference, textile materials are ubiquitous in medical devices. They are used in implanted (e.g. prosthetic arterial grafts, prosthetic valve sewing cuffs), percutaneous (e.g. catheters, sutures) and extra-corporeal (e.g. wound dressings, bypass pump tubing) devices. Depending on the use (in or out of the body, short or long term), these materials have limitations. They cannot modulate the body’s clotting response, which can lead to the blockage of blood flow in a prosthetic artery. Implants tend to remain “foreign”, which may lead to uncontrolled cellular growth at an artery&& interface (anastomotic intimal hyperplasia). Infection can occur as a result of bacteria attachment and growth to the textile substrate. Since the textile surface cannot combat this invasion, the healing of these materials can be adversely affected which can be fatal. A series of projects was begun more than a decade ago to deal with each of these problems as they affected prosthetic arterial grafts. These studies have resulted in numerous published papers and patents while broadening in scope to include catheters, wound dressings, masks and sutures. The work was based chiefly on taking an existing substrate (most often polyethylene terephthalate,polyester) and using established textile processes to modify the material surface. From these foundation studies, a “pad-heat” process was shown to provide polyester with long-lasting infection-resistance. Surface modification (hydrolysis or aminolysis) provided functional groups to which a range of bioactive proteins could be covalently linked while still maintaining activity. Using these modified surfaces, clot-prevention or promotion (depending on the end-use of the device) or cell growth-promotion properties (for prosthetic arteries) could be achieved. We have also shown that these effects could be combined, for example, to provide a wound dressing with both clot-promoting and infection-resistantproperties. While effective, these technologies have a number of limitations. The surface modification and subsequent crosslinking of proteins is a complex, multi-step process. The incorporation of antibiotics into preexisting polyester is limited to the substrate surface. The inclusion of antibiotic into the fiber during melt-spinning results in deeper incorporation but the antibiotic is “locked” within the substrate and unavailable for combating infection. The high temperatures involved in melt spinning could also denature bioactive proteins. Electrospinning has long been recognized but has recently become the focus of a considerable volume of research. A polymer solution is slowly extruded from the nozzle. A high voltage is applied to the polymer solution upon discharge from a small nozzle, which is then deposited onto a collector. The charged polymeric fibers are drawn across the gap to the collector by the electric field: as it does so, it is extended into low micron to nanometer-sized fibers.
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I
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I
An example of this process is shown
diagrammatically & Figure 1. The product that emerges can be varied by the control of several factors'. The first of these are the magnitude of the electric potential and the distance between the emitter and the collector. The s u r f m tension at droplet surface is also important, and is determined by the viscosity of the polymer solution, in turn elcctrospinning controlled by the solvent used, the molecular weight of the polymer, its concentration in solution, and the ambient temperature. Thus, there is considerable scope for the formation of subtly different materials. The potential of electrospinning has led to a rapid increase in research in this field over recent earsz294,including those investigating the formation of electrospun tubular structure^"^'7. For biomaterials, electrospinninghas been mainly confined to polymers such as polyurethane, PVA, PLGA, and proteins (e.g. collagen). These are typically of low strength and designed for dissolvable materials. Little has been reported on the electrospinning of polymers with more structural utility. Suture retention, bursting strength, breaking strength, tear strength and biodurability are critical to developing clinically useful implantabledevices. Polyester has been used in medical devices for over 50 years. Typical polyester fibers are formed through melt-spinning at temperatures of around 280°C with diameters of 15pm or more. Modified spinning methods have produced commercial polyester fibers with diameters ranging from 5-10 microns to low nanometers, but these still involve the use of high temperatures. In 2004, our group was the firstto electrospin polyester from solution at room temperature. The resulting material, comprised of fibers ranging in diameters h m IOOnm to 3000nm, possessed excellent physical and handling properties. We have published data showing that this material has qualities suitable for its use as a small-diameter prosthetic arterial graft8. Melt spun fibers are subjected to a hot drawing process to encourage polymer chain orientation and the development of crystallinity within the fibers. Electrospun polyester has been produced via melt spinningg, but in order to render functionality to the resulting matexial, gelatin was incorporated by subsequent surface m d i c a t i o n involving formaldehyde. This in turn improves physical fiber properties, but slows the diffusion of small molecular species within the fiber (thus, for example, undrawn polyester dyes more readily than drawn material). The shorter diffusion path out of fine fibers is responsible for lower color fastness of fabrics derived from them This study was conducted to examine the feasibility of incorporating an antibiotic into a solution of polyester to be used in electrospinning, and to examine the release of that antibiotic from the formed nanofibrous material.
I
EXPERIMENTAL
As those who work in fiber analysis understand, polyester is not an easy fiber to dissolve. Our work was made possible by the availability of 1,1,1,3,3,3-hexduor0-2propanol (HFIP). This solvent dissolves a wide range of materials including polyester. 200 0 Woodhead Publishing Limited, 2010
The boiling point of HFIP is 60°C, so it is rapidly volatilized upon electrospinningas well as from the resulting nanofibrous material. As was used in much of our earlier work on incorporation of antibiotic into existing polyester substrates, Cipro was the antibiotic chosen for this study. Antibiotics vary in structural type, spectrum of activity, and clinical usefulness”. Cipro is one of the fluoroquinolones,a family of more than ten antibiotics and the drug of choice for many Quinolone antibiotics are chemically stable, and effective at low concentrationsagainstthe common clinically encountered organisms, particularly those bacteria responsible for biomaterial infection’3. These antibiotics also have structural features (solubility, molecular mass, and functional groups) that coincide with those of textile dyes and our previous work has shown that these similarities lead to the potential for dye-like interactions with polymeric materiall~’~”~”~. Polyester chips were procured h m Zimmer (O.63dUgy 0.15% Ti02, 23Oppm antimony acetate catalyst). A polyester polymer solution (19%w/v) was prepared in icecold 100% HFIP. This polymer solution was mixed on an inversion mixer for 48 hours. This solution was spun on a practical embodiment of the theoretical electrospiuningset up of Figure 1, shown in Figure 2. This , T- I system consists of a Glassman power supply, a Harvard Apparatus syringe pump, an elevated holding rack, a modified polyethylene chamber, a spray head with power attachment, a reciprocating system and a Wheaton stirrer for controlled rotation of a PTFEcoated stainless steel mandrel (diameter = 4m). A loml ChemiCal-resiStant syringe was filled with the polymer solution. A stainless steel 18-gauge blunt s p h ~(0*5mm t internal diameter) was cut in half. The two ends were , rip 2 ~ I e L t r o y m i i i i i y,ippiii‘itu\ remnnected via 66cm of Nalgene PVC tubing (1/32 ID X 3/32 OD). The syringe fitting end was connected to the polymer-filled syringe, and the tip was attached via an electrical contact to the reciprocating system. The line was purged of air, with the syringe then placed onto the syringe pump. The mandrel was positioned 15cm Grom the tip of the needle. The mandrel was then grounded to the power source. The perfusion rate was set at ~mvhourat 25°C. Perfbion of the polymer was then started upon application of the power to the tip of the needle (+15kV) with electrospinning proceeding for 40 minutes. After this time, the end portions of the electrospun tube (lcm &om each end of the mandrel) were cut offand discarded. The remaining segment was then stretched 25% of the starting segment size while on the mandrel in order to provide a set strain across the fibers, a process that occurs in normal fiber extrusion. Materials thus prepared (nPET) were then either air-dried at 6OoC overnight or exposed to 100% ethanol for 2 hours at room temperature in order to remove the residual solvent followed by air-dryingovernight at room temperature. Following experiments to determine the solubility of Cipm in HFIP, a 19% polyester solution containing 1.5% (w/v) Cipro was prepared. This polymer solution WBS electrospun in the same manner as the control nPET material. Materials were either airdried at 60°C overnight or exposed to 100% ethanol for 2 hours at room temperature in order to remove the residual solvent. 0 Woodhead Publishing Limited, 201 0 201
The materials prepared were tested in several ways. Tensile strength (poundsforce), strain at maximum load (“h)and strain at break (%) for a conventionalknitted polyester fabric (Type 54 standard material) and electrospun nPET material were measured using published techniques”. Electrospun material was examined via a JEOL JSM 5900LV electron microscope in order to determine fiber size and distribution throughout the material. The successful incorporation of Cipro into the fibers of the resulting material was qualitatively indicated by the fluorescent properties of Cipro. Material with and without Cipro exposed to 60°C overnight or to 100% ethanol for 2 hours, was examined under a hand-held U V light The release of Cipro from these tubular constructs was assessed via WMS spectrophotometry. nPET and nPET-Cipro materials (0.5cm length) were placed into 5ml of sterile phosphate buffered saline (PBS) followed by continuous agitation at 37°C. Wash solutions were sampled at acute (0, 1,4 and 24 hours) and chronic (2 - 21 days) intervals, with the wash solution replaced with a fresh 5ml of sterile PBS after sampling. The absorbance of wash solutions was read at 27Onm (PBS blank) using a Beckman DU640 U V M S spectrophotometer. A standard curve using known Cipro concentrationsranging from 0 lOOpg/ml was prepared. This Cipro standard curve was then used to extrapolatethe antibiotic concentrationwithin the wash solutions. The antibiotic activity of the washed materials was then assessed via a zone of inhibition assay. A stock solution of S.aureus was thawed at 37°C for 1 hour. This stock solution (1 pl) was added to 5ml of Trypticase Soy Broth (TSB) and incubated Overnight at 37OC. Using this overnight inoculum, l O p l was streaked onto TryptiCaSe Soy Agar (TSA) plates. Unwashed and washed nPET and nPET-Cipro segments were then embedded into the streaked TSA plates and placed into a 37°C incubator overnight. Staudard Cipro Sensi-Discs (5pg Cipro) were embedded at each time interval as a positive control. The zone of inhibition each piece was determined, taking the average of 3 individual diameter measurements. Zone size (mm) at each sample period was determined for each parameter evaluated.
-
RESULTS The nPET tubular constructs, whether air-dried or exposed to ethanol followed by airdrying, had a consistent 4mm internal diameter throughout the length (average length = 7.5cm). Table 1. Physical properties of electrospun materials There was a marked difference between the break load of knitted polyester (42 f 9 pounds force) Knitted and nPET (3.7 f 0.9 pounds force) segments (Table 1). This 3.7 f 0.9 difference in breaking load was expected due to the significantly greater thickness of the knitted polyester material. The other physical properties such as the percent strain at maximum load and percent strain at break were comparable between the two materials indicating that the difference in break strength was directly related to wall thickness. Thus, the nPET material possesses physical characteristicsthat would permit application in various devices. Analysis of these nPET structures via SEM revealed that the diameter of the polyester fibers comprising the material varied f?om lOOnm to 300Onm (Figure 3). 202 0 Woodhead Publishing Limited, 2010
These fiber diameters were significantly less than those comprising knitted polyester material, which ranged from 15 to 30pm.
__
__.___
Fig. 3 SEM image of electrospun material
Fig 4. Fluorescenceof Cipro-containing nPET material
Based on our perfusion rate in conjunction with electrospinning time, approximately 30mg of Cipro was dispersed across the total segment length. Gross observation of the revealed intense fluorescence fiom the GET-Cipro segments, whether airdried or ethanol washed, as compared to the nPET segments demonstrating the presence of Cipro within the polymer (Figure 4). The release profile from the Cipro-loaded material is shown in Figure 5. Cipro release within the first 4 hours was consistent at 5 f 2pg/ml followed by a sharp increase to 13 f 4pg/ml at 24 hours. Cipro release then decreased to 6 f 4pg/ml by 48 hours, but persisted (ranging from 1-2pdml) throughout the length of this study (504 hours). The release of Cipro was reflected in the qualitative and quantitative evaluation of antimicrobial activity. SET-Cipro materials had significantly greater antimicrobial activity than nPET controls at all of time periods examined (Figure 6). The lack of antimicrobial activity in the nPET controls, comparable to non-nanofibrous polyester controls in earlier studies, shows that no residual toxicity remaitls from the presence of HFIP solvent. The zone of inhibition by the 5pg Cipro Sensi-Discs was consistent at 23mm. The nPET-Cipro antimicrobial activity profile correlated with the Cipro release determined in the spectrophotometric studies in that the greatest antimicrobial activity occurred within the first 48 hours. Cipro antimicrobial activity, due to lower Cipro concentrations being released as determined by the spectrophotometry, decreased slowly over the remaining time periods. However, significant antimicrobial activity was still evident at 504 hours, with zones comparable to the Sensi-Disc results. Thus, this study demonstrated that Cipro release persisted for over 504 hours, with antimicrobial activity correlating to Cipro release. The results obtained show release of Cipro at a consistent and long-lasting rate, in excess of that obtained from conventional polyester materials with Cipro incorporated into the surface, or materials in which Cipro is included in the material prior to spinning. In the absence of concrete information concerning the morphology of these electrospun materials, it is postulated that the greater release is brought about by an amorphous structure, in combination with fine fiber diameters. 0 Woodhead Publishing Limited, 201 0 203
T
0 """"'""'
0
Fig 5 . Cipro release from electrospun polyester over time
1
2
3
-
II
Fig 6. Antibiotic activity of electrospun polyester over time
Further work might establish the morphological characteristics of polyester spun in this way. Little work has been done to optimize this spinning process and changes in spinning parameters and/or post spinning drawing or annealing treatments might reveal even better results. Work is ongoing to examine the incorporation of other bioactive agents into the spinning solution, and the use of other polymers as substrates.
CONCLUSIONS Polyester can be electrospun at room temperature from solution in HFIP to produce a tine-fiber structure. Cipro can be added to the spinning solution and thereby incorporated into the final material. The Cipro is slowly and steadily released over an extended washing period. Development of a drug-loaded nanofibrous material with a slow-releasing antimicrobial agent has significant potential for use in medical devices such as wound dressings, catheter cuffs, repair mesh, prosthetic vascular grafts, sewing cuffs and the artificial heart, all of which have polyester components.
REFERENCES 1 J Doshi, D H Reneker, 'Electrospinning process and application of electrospun fibers', J Electrostatics, 1995 35 15 1.
2 R S Manley, US Patent Office,Pat No. 4 266 918, pulp and Paper Research Institute of Caaada, 1981. 3 M M H o b , G Shin, G Ruteledge, M P Brenner, 'Electrospinning, electrospraying and the instability of electrically forced jets', Part 1, Phys. Fluids, 2001 13 2221. 4 W J Li, E J Laurencin, E J Caterson, R S Tuan, F KKo, 'Electrospun nanofibrous structure: a novel scaffold for tissue engineering', JBiomed Mater Res, 2002 60 613. 5 D J Lyman, F J Fazzio, Synthetic Polymer Prosthesis Material, US Patent Office, Pat No 4 173 689,1979. 204 0 Woodhead Publishing Limited, 201 0
6 D Annis, T V How, A C Fisher, Recent Advances in the Development of Arrifcial Devices to Replace Diseased Arteries in Man: A New Elastomeric Synthetic Artey. In Polyurethanes in Biomedical Engineering, Planck H , Egbers G, Syre I (Eds), Elsevier Science Publishers B.V. Netherlands, 1984.
7 E Wong, et. al. US Patent Office, Pat No 4 475 972, 1984. 8 M D Phaneuf, P JBrown, M J Bide, F W LoGerfo, ‘Nanotechnology in cardiovascular devices: Development of a novel small-diameter vascular graft’, Proceedings, BioInterface 2004. 9 Ma et. al. Biomaterials 2005,26,2527 10 W Joklik, H Willet, Antimicrobial Agents, in Zinsser Microbiology -18th Edition, Joklik, W., Willet, H. Amos, D. (A), Appleton Century Crafts, 1984. 11 K Grohe, ‘Antibiotics-The New Generation’, Chemishy in Britain, 1992 28(1) 34.
12 M J Wood, ‘Therapeutic Focus: Cirpofloxacin’, Br JClin Prac, 1988 42 469. 13 A Fitton, ‘The Quinolones: An Overview of Their Pharmacology’, Clin Pharmacokin 1992 22(Suppll):l. 14 M D Phaneuf, C K Ozaki, M J Bide, W C Quist,J M Alessi, G A Tannenbaum, F W LoGerfo, ‘Application of the quinolone antibiotic ciprofloxacin to Polyester utilizing textile dyeing technology’, JBiomed Mater Res 1993 27 233. 15 C K Ozaki, M D Phaneuf, M J Bide, W C Quist, J M Alessi, F W LoGerfo, ‘In vivo testing o f an infection resistant vascular graft material’, JSurg Res, 1993 55 543.
16 M D Phaneuf, M J Bide, W C Quist, F W LoGerfo, Merging of Biomedical and Textile Technologies in order to Create Infection-Resistant Prosthetic Vascular Gra@s, in Anti-microbiaVAnti-infective Materials; Principles, Applications and Devices, Sawan, S.P. and Manivannan, G. (A), Technomic Publishing, Lancaster, PA. 17 M D Phaneuf, W C Quist, M J Bide, F W LoGerfo, ‘Modification of polyethylene terephthalate (Polyester) via denier reduction: Effects on material tensile strength, weight and protein binding capabilities’, JApplied Biomater, 1995 6 289.
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DEVELOPMENT OF ODOUR (VOLATILX MOLECULE) ADSORBENT MATERIALS FOR HEALTHCARE G. Lee', S. C. Anand', S. Rajendran' and I Walkel? Institute for Materials Research and Innovation, The University of Bolton, Bolton, BL3 5AB, UK * Lantor(UK)Ltd, Bolton, BL3 3PP, UK
'
ABSTRACT Wound malodour is rapidly becoming a critical issue, particularly with patients suffering with c h n i c illness that often result in wounds such as; venous leg ulcers, diabetic ulcers, pressure ulcers and hgating (malignant cancerous)lesions. The malodour is usually just part of the whole chronic situation but it can affect the patient in numerous social and psychological ways. There are specific wound dressings on 'Drug Tariff to treat malodour. These contain a layer of activated chacoal which facilitates the adsorbing of wound malodour. Although activated charcoal is efficient in the adsorption of volatile odorous molecules, there some issues with its use in wound dressings and these are: a) Activated charcoal cloth is black incolour; b) it is relatively weak in nature and can be easily ruptured and presents a risk of the broken hgments of carbon fibre contaminating the wound, if exposed; c) the efficiency of the ability to adsorb odorous volatile molecules is compromised if saturated with the molecular rich wound exudate; and d) activated charcoal cloth is relatively expensive to produce and this is often reflected in the cost of the final products. In order to address the above limitations, a research programme is in progess at the University of Bolton one of the objectives of this research is to investigate and develop a viable test method for evaluating the efficiency of odour adsorption, whilst researching and developing novel odourholatileadsorbent materials, to possibly replace the use of activated charcoal. To date there appears to be a dearth of quantitative comparable data on these specific wound dressings particularly on their odour adsorption efficiency; this may be due to the limitation of realistic test methods of evaluating this characteristic. Further research work has been carried out on a novel test method for odour adsorption that has combined the efficiency of odour adsorption together with the assessment of fluid handling capabilities. Although there still some criticisms with this method it appears to be the nearest, to date that simulates some of the physical conditions that the product would experience in use. A selection of currently available activated charcoal wound dressing products have been tested, evaluated and quantitative comparable data collected. Some natural polymeric antimicrobial agents have also been tested and evaluated for their potential d o u r adsorption efficiency. These results will enable us to develop, engineer and characterise a range of novel odour adsorbent materials by using innovative fibredpolymers, fabric structures and composites incorporating adsorptive and antimicrobialproperties.
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INTRODUCTION Wound malodour is rapidly becoming a critical issue, particularly wih patients suffering with chronic illness that often result in wounds such as; venous leg ulcers, diabetic ulcers, pressure ulcers and fungating (malignant cancerous) lesions. The malodour is usually just part of the whole chronic situation but it can affect the patient in numerous social and psychologicalways. Wound malodour is due to the presence of necrotic (dead tissue and/or the result of severe colonisatiodiection of bacterial m i c r o - ~ r g a n i s m5 s).' ~These ~ ~ ~ malodorous microorganism are of the bacteroides and clostridium species, in a cocktail of different volatile agents, like n-butyric, n-valeric & n-caproic acids, amines and diamines such as cadaverine andputrescine, that are produced by the metabolic processes'*4p5. There are specific wound dressings on the 'Drug Tariff to treat malodour. These contain a layer of activated charcoal which facilitates the adsorption of the wound odour. Activated carbon is efficient in adsorbing these odoroudvolatile bacterial micrcmrganisms but it does not have bactericidal or bactaia-static characteristics, also there are some other issues with regard to its use in wound dressings, these are: a) Activated charcoal cloth is black in colour; b) it is relatively weak in nature and can be easily rupturedand presents a risk of the broken fragments of carbon fibre contaminating the wound, if exposed; c) the capacity of adsorption of adsorb odorous volatile molecules is compromised when saturated with the molecular rich wound exudate; and d) activated c h a m 1 cloth is relatively expensive to produce and this is often reflected in the cost of the final product To date, there appears to be a dearth of quantitative comparable data on these specific wound dressings, particularly on their odour adsorption efficiency; this may be due to the limitation of realistic test methods for evaluating this characteristic. Further research work has been carried out on a novel test method for odour adsorption that has combined the efficiency of odour adsorption together with the assessment of fluid handling capabilitie2. Although there are still some criticisms concerning this test method it appears to be the nearest simulation to some of the physical conditions that the product would experience in use. In this study, a selection of currently available activated charcoal wound dressing products have been tested, evaluated and quantitative comparable data collected. Some natural polymeric antimicrobial agents are also under investigationfor their potential odour adsorption. Ultimately the results from these evaluationswill enable us to develop, engineer and characterise a range of novel d o u r adsorbent materials by using innovative fibredpolymers, fabric structures and composites incorporating adsorptive and antimicrobialproperties. ODOURADSORBENT MATERIALS Activated Charcoal Cloth ACC The use of charcoal (carbon) in the adsorption of wound odour has been known from as early as 1550 BC, as depicted by the ancient Egyptians'. After in-depth research during the 1800's it was discovered that the potential adsorbency of the carbon rich matter can be increased by further controlled pyrolysis and therefore creating what is now known as activated carbon6. Carbon-rich regenerated cellulose viscose rayon fabric is used as the precursor for the activated charcoal cloth ACC, found in most of the currently available
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odour adsorbent wound dressings. The viscose rayon fabric is subjected to a chemical p r s treatment followed by a sequence of controlled high temperature exposures in an atmosphere of nitrogen or more commonly carbon dioxide During the treatment the s&e area of the carbon matter (viscose fibres) vastly increases, this is in the form of small macro and micro pores (0.5nm and 0. Inm) creating highly amorphous porous fibres. This results in a carbonised material resembling the original viscose rayon knitted and/or woven fabric, although now black in colour and with a drastically reduced mechanical properties, therefore h g i l e to moderate physical forces. The odorous volatile micm organisms/ bacteria floral are attracted to the surface of the activated charcoal via intermolecularforces and on contact they become attached by a bond (Van der Waal force) which securely holds the offending odorous molecules in place entrapped w i t h the charcoal structure6. Although the known available surface area ofthis activated charcoal is immense making it highly adsorptive to micro volatiles, it is now known that the macro sized pore/sites can be prematurely saturated by the larg fatty acid molecules found in wound exudate compromising its odour adsorptive efficiency, one of the issues mentioned in the introduction.
'.
Alternative volatllelodour adsorptive materials Novel odow aakorbent textilefinishes
There are many new and innovative fibredyams, fabrics and textile finishes that offer antimicrobial characteristics, and now there is evidence that some also have odour suppressionladsorptioncharacteristics. Polysaccharide fibres such as; chitidchitosan and alginate plus some novel carbohydrate polymers (e.g. Branan ferulate)8 all with the potential of odour adsorptive characteristics. There are textile products containing novel ammonium zeolite and cyclodextrin finishes Zeolites are inorganic material that are similar to activated charcoal in having a highly microporous and mesoporous structure with the ability to adsorb volatile molecules. Cyclodextrins are polysaccharides with a molecular shape of six to eight D-glucose units, which fonn a bucket shaped molecules with a hydrophobic cavity. The cavity has the ability to attract and encapsulate volatildodorous molecules, plus they can store fragrant molecules or specific drugs that can be released0*". Cyclodextrins have now been introduced into an adhesive hydrocolloid woundcare product; the cyclodexh-ins have been chemically incoprated into the complex adhesive m a d ' . Textile finishes derived from copper and zinc are also under investigation into their odour adsorptive characteristics, for example, reactive dye molecules derived from copper salts, plus there has been recent research into deodorizingproperties of mordant as well as acid dyes". These novel odour adsorbent finishes have been initially promoted in active and sports apparel applications where as materials intended for woundcare require certain critical criteria's and specifications". The research is omgoing into tbese new novel finishes into eliminatingany rislds of toxicity, or leaching.
'.
Potential natural remedies
There are many old and ancient remedies with desirable anti-microbial characteristics as well as a history for use as alternative remedies in woundcare. There are animal-derived
208 0 Woodhead Publishing Limited, 2010
products like; fish oils, sheep's wool &anoh, Silk cocoons)13and milk (as butter milk 8c live yoghwt as lactic acid)I4. Herbal extracts and balms for example; Calendula o#cinalis, Tannins (oak bark, witch hazel), tea tree oil (Melaleuca alternifolia), mem oil (Azadica hdica) and aloe vera (Barbadensis miller) 's,'6, plus sugar, sugar pastel7 silver and honey (Manuka)13J*. Some of these agents have recently been reintroduced into modem wound management particularly for treating difficult-to-heal wounds, for example; silver, honey (Manuka) and aloe vera. Laboratory studies have demonstrated that honey has a broad antimicrobial spectrum; a) it has the hyperosmotic characteristic of high sugar believed to inhibit bacterial growth, b) Acidity, and c) it contains low levels of antiseptic hydrogen peroxide. Man& Honey is a specific type of honey derived from bees bred on Manuka (Leptospermum scoperium (Myrtaceae)) plantations in New Zealand This has been shown to possess the best antimicrobial characteristicsof all other types of honeys evaluatedI9. Aloe Vera (Barbadensis Miller) as most of other natural remedies mentioned above is composed of polysaccharide. Polysaccharides have the potential for odour/volatile adsorption, but not all polysaccharides are the same. Aloe Vera is a complex plant containing many biologically active substances as well as polysaccharides. The gel polysaccharides in aloe vera are immune stimulatory or improve wound healing especially the acetylated mannans Aloe vera also contains many other beneficial ingredients like; vitamins, minerals, enzymes, sugars, anthraquinones or phemlic compounds, lignin, saponins, sterols, amino acids and salicylic acid Aloe Vera has also shown antibacterial and antifungal activity in laboratorytests 16.20. A selection of these old natural remedies is under investigation for their potential in adsorbing malodour. There is a growth of supportive scientific research and clinical data on the potential benefits of these possible alternatives.
EXPERIMENTAL WORK
Test method The description of the test apparatus is described elsewherd (Thomas et al 1998), and is shown in Fig 1. The apparatus comprises of a horizontal stainless steel plate rig, with a central circular recess of 5Omm diameter and 2mm deep. There is a small hole in which the volatile/malodoroustest solution is fed via a mechanical syringe pump. This is to simulate an exudating wound. The test solution consisting of sodium/calcium chloride solution containing 142 mmol of sodium ions and 2,5mmol of calcium ions as the chloride salts Cfie concentration of which is quoted to be comparable b human serum or wound exudate), 2% diethylamine (odorous volatile) and 1Oohnewborn bovine serum (fatty acids), simulating wound exudate.
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Fig I. Novel efficiency of odour adsorption test equipment. (Courtesy of SMTL) A lOcm X lOcm test specimen (dressing) is then placed centrally over the mess and attached securely down each edge with a waterproof medical adhesive tape. The mechanical syringe pump is activated and the test solution is slowly introduced to the lower wound contact face of the test specimen. The stainless steel plate rig is fitted with an airtight Perspex chamber that is placed directly over the test specimen and the air in the chamber is monitored via a Miran 1B2 ambient analyser @Ispectroscopy),every 5 seconds for the detection of diethylaminevolatile. The collected data is converted into time/duration and volume of test solution in ml. The test dressing specimens are continuously monitored to assess any strikethroughand/or leakage of the test solution. For this study a selection of commercially available Activated charcoal wound dressings were assessed for their efficiency of odour adsorption. These dressings were CarboflexB ConvaTec, Lyofoam C@ SSL, Carboneto Smith & Nephew, Sorbsan plus carbon@ ConvaTec, Actisorb Silver@ Johnson & Johnson, ClinisorbOB CliniMed, Carbopad VC@ Vernon Carus, and a non odour adsorbent basic dressing MelolW Smith & Nephew as a Standard.
RESULTS The results of this study demonstrate the varying physical differences between the selected wound dressings assessed and average results are shown in Table 1. Two of the dressing types showed very low WVTR (Water Vapour Transference Rate) and air permeability. The Carbopad VCQ specimens showed very low/minimal air permeability, exhibiting an occlusive characteristic; this presented problems during the test to evaluate the efficiency of odour adsorption and was therefore withdrawn from this test. The fluid handling capabilities of a wound dressing product can influence its ability to contain the malodorous test solution and therefore delay the release of the volatiles/odours into the surrounding air. This was demonstrated by the basic wound
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Table I . Average test results. WVTR Water Vapour Transference Rate (g md 24hr")
Air Permeability (cm3sec")
Average efficiency of odour adsorption (time in min to 15ppm ET2NH2) 20.19
Carboflex
4160
28 21
Fluid handle Absorption test (mi Iwcm'*) 42 98
Lyofoam C
2800
0 99
19 39
634
Carbonet
4640
13 02
45 56
10 23
Sorbsan with carbon
4640
17 36
40 14
11 32
Actisorb silver
6560
39 45
7 15
12 5
Carbopad VC
1600
0 07
7 94
N/A
Clinisorb
6560
33 93
10 01
8 56
Std Melolin
4967
26 43
34 23
404
Wound dressing
I
-
Acthiorb Silver Sorbsan with Carbon Carbonet
-:
Lyofoam~ 000
600
3 6 Yln Is eqwvalent l o 24
10.00
i5.00:
ZOfw
Time in minutes (showin
Fig 2. Range of results from the novel test method.
[lIIl
llllllal
absorplion
nange
01 n ~ r l up lake measured
A c l i ~ o r bSilver
[
borbsdfi willi Carbon
1 Maximum
capaaly of absorbence ( 0 s EN 13726 12002)
0
5
10
15
20
75
yl
35
1G
45
Y)
Fluid (ml)
Fig 3. Volume of test solution absorbed during testing.
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dressing Melolin@ (Smith & Nephew), as it appeared to initially delay the penetration of the malodour through its fibrous construction.As expected, all the ACC dressings delayed the penetration of the volatiledodours for longer periods that the Melolin dressing with results ranging h m a minimum of 3 minutes to a maximum of 30 minutes. In a previous study by Thomas et al it was calculated that a leg ulcer can exudate at the rate of 0.Sml/cm2/24hr , the test solution was set at a rate of 36.7mVcm2/24hr therefore it was deduced that approximately 16 minutes in the test rig is equivalent to 24 hours in use. Overall, CarboflexB (ConvaTec) dressing showed the best results as regards the efficiency of odour adsorption, with recorded result times from 9 to 30 minute duration in the rig (estimated 13 to 45 hours in use). Actisorb@ Silver (Johnson & Johnson), also appeared to yield good results with a recorded duration time fiom 11to 16minutesin the rig (estimated 16 to 24 hours in use). None of the other ACC dressings reached the 16 minutesin the rig and therefore have a potential odour adsorption in use of less than 24 hours, see fig 2. During testing, it was observed that the test solution would often seek the easiest route of resistance, and in some of the dressing specimensthe test solution would leak out at the edges rather than penetrate through all the layep. For some of the highly absorbent dressings it was found that the test solution would prematurely strike through the multilayer, without using the dressing’s potential absorption capacity, see fig 3. This novel test method works on the principle of detecting the volatile (diethylamine) based on the penetration of the test solution by either strikethroughor leakage. Therefore,the ability of a dressing material to adsorb and retain the malodorous solution and yet maintain its other desirable characteristicsis required.
CONCLUSIONS
ACC is generally excellent as regards adsorbing volatile/odorous molecules, however as mentioned earlier it presents some limitations in its use in specialist wound dressings. Alternative products m required that offer additional antkmicrobial characteristics that will adsorb, entrap and kill the volatile bacteria causing the wound malodour. This is in addition to maintaining other desirable characteristics such as control of vertical wicking; retention of the absorbed fluid whilst maintaining a moist wound contact layer in order to promote wound comfort and healing. In order to seek possible alternatives to the ACC currently used, it is important to establish a quantitative test method. Therefore working in collaboration with the Surgical Materials Testing Laboratory (SMTL) Cardiff, UK,fUrther research into this novel method for evaluating both the odour adsorption and fluid handle will be carried out. To date this method appears to be the most efficient method of determining quantitative comparable data of different dressings both commercial and expenmend Textile fibre assemblies have a very large specific surface are@and therefore have the ability/potentialto attract, adsorb and diffusevolatile substances. With the correct selection of polymer /fibres, fabric structure(s) and their arrangement, combined with an appropriate selection of potential anti-microbial odour adsorbent agent@)an alternative to the currently available ACC wound dressings can be designed and engineered. No two wounds are alike and the demand for finding the ideal wound dressing is often confusing and difficult. The cause of the mund malodour is the main concern of the clinician, while the problem of the malodour is one of the top three concerns of the patienls and their quality of life. Therefore a better understanding of the physical characteristics of
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dressings, as well as continued research and knowledge into the causes and treatment of the malodour are vital.
REFERENCES 1 P G Bowler, ‘Microbial involvement in chronic wound malodour’, Journal of Woundcare 1999 S(5) 216-218.
2 M Benbow, ‘Malodorous wounds: how to improve quality of life’, Community Nurse, 1999 5(1) 4 3 4 6 . 3 S Thomas, B Fisher, P Fram, M Waring, ‘Odour adsorbing dressings: a comparative laboratory study’, Journal of Wound Care, 1998 7(5) 246-50. 4 F Murray, ‘Malodour in diabetic foot wounds’, The Diabetic Foot, 2005 8(3)122-132.
5 K Williams, ‘Malodorous wounds: causes and treatments’, Nursing and Residential Care, 1999 l(5) 276-85. 6 J W Hassler, J. W. Activated Carbon: chemical & process engineering. London, Leonard hill 1967.
7 .IWildman, F J Derbyshire, ‘Macro porosity in activated carbons: its origins and functions’, Paper for Sutcliffe Speakman Carbons Ltd, Guest Street, Leigh, 1980. 8 J F Kennedy, C J Knill, ‘Biomaterials utilized in medical textiles an oveTViewy,3rdh t confMedica1 textiles and biomaterialsfor healthcare, Bolton UK, Woodhead, 2006.
9 K Takai, T Ohtsuka, Y Senda, M Nakao, K Yamamoto, J Matsuoka and Y Hirai, ‘Antibacterial properties of antimicrobial textile products’, Microbial Immunol, 2002 46(2) 75-81. 10 W D Schindler and P J Hauser, Chemical finishing of textiles: Novel finishes, Cambridge, Woodhead, 2004. 1 1 R D A Lipman, R.D.A. ‘Odour-adsorbing pressure-sensitive adhesives for medical applications’, Business briejng: medical device manufacturingh technology 2004.
12 Y Kobayashi, ‘Deodorizing properties of cotton fabrics dyed with direct dyes and a copper salt’, Textile Research Journal, 2002 72 125- 13 1 13 K Cutting, P Davies, ‘Natural therapeutic agents for the topical management of wounds’, Woundrr UK,2006 Mesitran Honey supplement, 4-1 3
I4 L B Welch, ‘Buttermilk & Yoghurt: Odour control of open lesions’, Reg. Nurse, 1981 44 42-43.
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15 J Graf, ‘Herbal anti-inflammatory agents for skin disease’, Skin %ram Letter, 2000 S(4) 3-5.
16 M K Bedi, P D Shenefelf ‘Herbal therapy in dermatology’, Archives of Dermatology, Chicago, 2002 138 232-42. 17 H Gordon, et al. ‘Sugarand wound healing’, 7he Lancet, 1985 2 663-664 18 P C Molan ‘The role of honey in the management of wounds’, Jownal of Woundcure, 1999 8(8) 415-418 19 K L Allen, P C Molan, G M Reid ‘A Survey of the antibacterial activity of some New Zealand honeys’, JPharm Phannacol, 1991 43 817-22. 20 P Atherton, ‘Aloe Vera: magic or medicine’,Nursing St&d,
1998 12(41) 49-54.
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DEVELOPMENT OF A DECISION SUPPORT SYSTEM FOR DETERMINATION OF SUITABLE DRESSINGS FOR WOUNDS K. G. Karthick’, M. Miraftab’ and J. Ashton’, ’Institute for Materials Research and Innovation,Universityof Bolton, Deane Road, Bolton BL3 S A B , UK 2BoltonPrimary Care. Trust, Bolton, BL1 IPP,UK
ABSTRACT Given the increasing autonomy of nurses in delivering patient care. and wound care management in particular, they are more than ever engaged indecision making associated with the assessment and treatment of wounds. To select and administer the ‘%ght” dressing from a wide variety of wound dressings available is not an easy task. There are. currently over 650 brands of wound dressings to choose fiom, but it is even more difficult because no one dressing suits all wounds and the choice is dependent on the cause of the wound and will be influenced by the presence of infection, the state of the individual’s health, the nurses prior and existing knowledge of wound care, availability of products and cost. Because of these complexities, nurses are becoming confused regarding wound care practice and research shows that in 85% of cases nurses are using inappropriate dressings and have difficulty in applying their theory and knowledge to their practice. This confusion leads to over consumption o f wound dressings thus increasing the c o d and perhaps more importantly increasing the valuable nursing time required. This web based project aims to optimise the usage of such resources, especially the nursing time available, by reducing the above 85% by developing an evidence based decision support system which would bring together the wound dressing selections made by the nurses from various geographic locations, after being peer reviewed by different tissue viability nurses. It will eventually use an expert system to suggest a choice of wound dressings for a particular wound from the information provided and based on the dressings already selected with the given criteria. It will also provide a comprehensive guideline to wound care and will have an important role as a learning package for student nurses and health workers within wound management. This paper will discuss the methodology used to design such adecision support system. INTRODUCTION Wound management is an ongoing treatment of a wound, by providing appropriate environment for healing, by both direct and indirect methods, together with the prevention of skin breakdown. Proper Management is determined by the wound’s size, depth, severity and location over the care period This management is changing rapidly due to the advancement in technologies which is shedding more light onto the aetiology of the wound and its healing process’. Nurses play a crucial role in the management of wounds They need to have good current knowledge and be more aware of their own wound care practices so as to bring about more effective wound management Nurses are the ones who take care of every single aspect of the patient right from record keeping, prescription handling to basic first aid. They have direct impact on the patients.
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Wound care management is becoming more complex for nurses due to new insights into wound healing and because of the wide variety of w m d dressings that are available Erwin-Toth and Hocevar (1995) stated that there w r e approximately 400 brands of wound care dressings on the market to choose from and that wound care is made even more difficult because no one dressing method suits all wounds and the choice is dependent on the cause of the wound, infection, favourability and cost (Findlay, 1994). Because of these many different wound care techniques and dressings, nurses are becoming nonplussed regarding wound care practice. Alarmingly, Millers (1994) research showed that in 85% of cases nurses were using inappropriate dressings, and O'Connor found in her studg on wound care that nurses were having difficulty in applying their theory and knowledge to their practice. The results of the study taken by Barlow to find who selects the product used in the management of leg ulcers indicate that 53/57 (93%) district nurses and 33/43 (77%) practice nurses perceive themselves as always or fbquently making the decision. The perception that the majority of GPs never or rarely make this decision was shared by 54 (95Y0) district nurses and 30 (70"h)practice nurses. These results suggest that, for this sam ple, nurses perceive themselves to be the decision-makers on most occasions? Similar study conducted by Boxer and Maynard revealed that registered nurses had significant role in chronic wound management and that their decisions were mostly based on their own experience and that of their colleague$. Another part of this study also suggests that nurses are not using the best available evidence because of inaccessibility of resources and lack of time to search the literature. Nurses also cited difficulty in discriminating between a biased presentation and reliable research. Nurses are basically not accessing the best information that is available to them. They are relying on the nursing colleagues for advice and it also appears that ironically, their colleagues are not accessing the most reliable and conclusive information? In fact nurses in all specialities regularly make clinical decisions on direct patient care, but lack clinical decisions in supervision, management and extended roles! There were also differences in the decisions made between nurses in critical care and other areas of nursing.
RESEARCH AMONGST NURSING STAFF As of 2003, there were 386,359 nurses in the UK. Even 1% representation would mean 3864 nurses and with 301 Primary Care Trusts (PCT) in the United Kingdom (UK) (as of April 2004) we would need at least 13 responses from each PCT. If the sample population was to be reduced to just the tissue viability nurses, nurses from various PCTs from different parts of the country, could be selected with sample of 10 tissue viability nurses from each county. With 39 counties in the UK, this would lead to 390. This would in no way be a representation of the whole nursing population in UK but could still be sufficient representation of the nurses who are active in wound care services. However, the time limit and financial constraints associated to these kinds of activities are not always in favour of such investigation. For this reason convenience sampling was used and carefully designed questionnaires were sent to different PCTs in which at least one of the nurses was known directly or indirectly.
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The prime objectives of the questionnaires were: 0 To identify the factors responsible for selection of wound dressings; 0 To identify the resources that were used to select a wound care product To find out whether they, the wound care nurses, would find it helpful to access the wound care information in a single place; and To find out whether they would be willing to use a computer aided decision making tool even if it might be time consumingto begin with.
Survey results The sample target was set at 100 respondents and a total of 175 questionnaires were sent out by post and few were given out in person. The total number of respondents were only 44. The results were consequently consolidated and analysed using the 44 received responses. No further attempts were made to reach the sample target due to time restrictions. The study showed that 73% (32) of the respondents refer to journals and British National Formulary and 20% (9), some of which (5) included in the above 32, also sought the opinion of their senior members of staff or their colleagues. Only 11% (5) of the respondents used the internet and only two mentioned that they did not use the internet because they did not have access to that resource. The most frequently referred resources were the wound care formulary and the nursing journals. When asked whether they would avoid referring to any of the resources because of the amount of time it consumes, 77% (34 out of 44)gave negative replies. Almost all the respondents except one agreed that they would like to have all the relevant information that helps them in making a choice to be available in a single place. 70% (3 1) of the respondents preferred to have them as a website even though only 11% admitted using the internet. Another 11% (5) apart from the 70% preferred both the website and a CD-ROM while 18% chose just the CD-ROM. The respondents who claimed to have used the internet for research have all preferred to have it as a website and they were either a grade E or grade F nurses. 93% (41) of the respondents expressed interest in using evidence-based decision support system to make a choice, if available. Two respondents said that they would not give it a try. 25 out of the agreed 43 (56%) mentioned that they would use the decision support system regularly and 18 of them said they would even if it was time consuming to being with. The other 44% (18) agreed to use them only when it would be difficult for them to make a decision on the choice of the dressing.
THE NEED FOR A DECISION SUPPORT SYSTEM Shared decision making between doctors and patients is an issue where computer systems may develop an important rule? Cost effective and appropriate care of chronically wounded patients is an outcome that must be attained in the near future as the number of people affected by chronic wounds burgeons in the next 20 years. Algorithms, decision trees, critical pathways, and computer software that include these processes may make this goal possible.
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In wound care alone, there are a number of guidelines in which most of the recommendations are based on very little evidence. This is largely due to the lack of high qualiq randomized controlled trials (Dickson 1996, Renvoize et al, 1997, Haycox et al 1999) . The financial and human cost of pressure ulcers and other wound care conditions is high. Inappropriate wound management can have adverse affects on the healing process and is a waste of precious resources. Thomas and Bale et af have also highlighted variations in the cost of wound management dressings, underlining the importance of appropriatetreatment. The current emphasis on the use of evidence to support clinical interventions has entered a new phase with the establishment of the National Institute for Clinical Excellence (NICE).One of the early issues that are being addressed by NICE is the prevention of pressure sores, which will add considerablytothe body of knowledge about tissue viability. One of the key problems for NICE and other review groups is how best to disseminatetheir findings and recommendations to practitioned. The philosophies behind NICE, Commission for Health Improvement (CHI) and clinical governance are to make real improvements in clinical care - to iron out differences in practice between geographical areas, to implement best practice and eradicate outdated methods, and to make the whole system more accessible and a patient-fiiendly ex rience. Sir Muir Gray’rDirector of Clinical Process, Knowledge Management and Safety at Connecting for Health (CM, formerly the National Programme for Information Technology), has said: “Computerised decision support systems have the potential to support clinicians through the combination of computing technology and upto-date clinical research and information.”
EXPERT SYSTEMS IN MEDICINE Expert systems, as defined by the encyclopaedia, are programmes made up of a set of rules that analyze information (usually supplied by the user of the system) about aspecific class of problems, as well as provide analysis of the problem(s), and, depending upon their design, recommend come of actions in order to implement corrections. In layman’s terms, Expert Systems are computer programmes that are built to perform at a human expert level in a narrow, specialiseddomain. In medical terms, Medical Expert Systems are described as active knowledge systems which use two or more items of patient data to generate casespecific advice (Medical Informatics: Computer Applications in Health Care Shortliffe & Perrault). Although extensive evidence has highlighted the difficultiesencounteredin implementing paper-andpencil practice guidelinesand algorithms, many studies have shown that computerized systems have the potential to overcome these constraints, resultingin improved physician use and patient outcomes’ One such system is the Health Evaluation through Logical Processes W L P ) system, which is the longest running and most successful clinical information system Concepts developed with the HELP system have shown that:
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a) Clinical care can be provided with such a system. b) Computerized decision-support is feasible. c) Computerized decision-support can aid in providing more cost-effective and improved patient care; and d) Clinical user attitudes toward computerized decisionsupport are positive and supportive.'2
Evidence for feasibility of a decision support system Decision Support Systems @SS) are clinical consultation systems that use population statistics and expert knowledge to offer redtime information for clinicians. There have been a number of studies that has proved Clinical Decision Support Systems (CDSS) improve practitioner p e r f o ~ ~ ~ ~ ~ ~ c e ~ ~ . A computerised decision support system, for the management of stroke patients, that incorporated the findings of 960 Markov models examining the decision to prescribe as irin in the secondary prevention of stroke, was developed, and evaluated by Short D et alp4' using 15 GPs from the west Midlands. It was found that the GPs were more certain of their decision making and were more inline with the national guidelines It was suggested that the system made decision making easier, improved feelings of being supported, improved the quality of decision making and increased satisfaction. Tele-health has already been proved as golden opportunity to enhance quality wound care, improve availability, reduce costs, and provide outcomes datak5. A pilot study has proved that there is no difference between the healing times of foot ulcerations that were managed through telemedicine and diabetes foot prognurme groupsk6. Another pilot study which compared telsassessment with live assessment of pressure ulcers in a wound clinic has come out with the result that 89% of the assessor 's have agreed that telsassessment compared well with in-person assessment. This shows the potential accuracy of digital image and photographs in the diagnosis of patient conditions". Many of the previous research work show that guidelines disseminated through traditional educational interventions have minimal impact on physician behaviour. Providing focused training to key people in a practice and supporting subspecialisation through computer decision support may be a more appropriate approach to chronic disease managementin primary can?'. A 2-year project carried out in Canada to evaluate the use of multi-component, computer-assisted strategies for implementing clinical practice guidelines Evaluation indicated an increase in knowledge relating to pressure ulcer prevention, treatment strategies, resources required, and the role of the interdisciplinaryteam." In a randomised controlled trial, Tiemey et al (1993) demonstrated that patients treated by physicians who used a Personal Digital Assistant (PDA) containing decision support, which included costs of specific drugs and diagnostic tests, had less expensive hospital stays. Extrapolation of the cost savings due to reduced costs per admission was in the order of $3 million for the teaching hospital.
Internet as a tool for a decision support system The Internet having evolved as a potentially useful tool for guideline education, dissemination, and implementation because of its open standards and its ability to provide
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concise, relevant clinical information at the location and time of need two clinical DSS's based on national guidelines were developed by Thomas EW et a t o and published on the Internet and both systems improved physician compliance with national guidelines when tested in clinical scenarios. By providing information that is coupled to relevant activity, it is expected that these widely available DSS's will serve as an effective educational tools to positively impact physician behaviod' . Already a web based Critical pathway is being used for radical nephrectomy which has improved health outcomes b reducing the hospital stay and admission charges and by improving the quality of care' Y. The NICE and CM are already undertaking a pilot study to develop and pilot methods for evaluating computerised decision support systems (CDSS). This project is to find whether any existing NICE methodologies such as Technology appraisal progamme could be applied to the evaluation of the CDSS.
DECISION SUPPORT SYSTEM FOR WOUND DRESSING SELECTION Evidence shows that a decision support system has contributed a great deal to the medical field. So an appropriate decision support system is requhd which can collect the data from different trusts. Internet is the commonly available, inexpensive media that is accessible h m any geographic location. So the DSS should be web based. The other advantages of hacng a web based solution are: a) All the information is available fiom a single source. b) All the information can be accessed and updated from any location. c) It can be peer reviewed from any part of the world. In the survey some have stated that they don't have access to the internet in their trusts only to intranet. But current technologies permit the users, through the configuration of a firewall, to access particular sites. The website can also be used as a leaming package where the wound care related materials can be accessed. It can act as a wamd care guideline which concentrates more on the selection process and its description rather than the current research that are being carried out in that particular field. Considering the above, increasing use and availability of internet, a website is being developed which will be carried out in two stages. This paper focuses on the decision support system rather than the learning package. The proposed functional operation and model of the decision support system after its completion is shown inFigures. 1-3.
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Fig 2 Library of possible wounds
LIB I Wound location guide
I
Ixudrlp.
I
a'.
..
'
r.-,m'.,,m.J1I .(w
.a
* Ad *c1
Fig 3 Typical wer interface page
The user identifies the location of the wound on the software system depicting full body figure and is presented with an array of possibilities in terms of wound type, size, depth, age etc. and amount of excaudate excretion, pain leveland so forth. Once the user has entered the requested data, the procedural route follow the decision support system as depicted in Figure 4.
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r I
I I
I I
I I I
I I I
I
I I I
I I
'
:
~
i
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Reviewing
Fig 4. Proposed Model ofthe Decision Support System
The users have to login into the system in order to use it. The users are split into 2 user p u p s . The first being the nurses and the second being the peer reviewers who could be experienced specialist nurses or even doctors. The information that is entered by the nurses is stored as Extensible Markup Language (XML) files. XML is a set of rules for defining semantic tags that break a document into parts and identify the different parts of the document. It is a metrtmarkup language that defrnes a syntax in which other domain-specific markup languages can be writtea XML Applications are developed using this XML for a specific domain with its own semantics and v~cabula$~. Some of the well known Applications are Chemical Markup Language (CML) for Chemistry, Gedh4L for Genealogy, Mathematical Markup Language (MathML) for mathematical equations, MusicML for Musical Applications, etc.
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The role of the deciaion support system
The main role of this decision support system is to collect the various characteristics of the wound and the dressing selected for that particular wound. Once a large database starts to build up, subsequent users can enter the characteristicsof the wound andobserve what type of wound dressing were selected for similar wounds. The DSS software will generate the results based on the number of such matched wounds and give a total number of times each type of particular dressing were selected. If a decision is made, then that decision is also added to the database thus updating the DSS accordingly. The role of the reviewer
For each entry that is being made into the system. A reviewer has to aprove that the information provided is true. A reference to the evidence used may be attached so that it helps the reviewer to approve quickly. If the reviewer thinks that the choice made is inappropriate, helshe may reject it from being entered into the llain database server and can state a reason as to why it was rejected and send it back which can then be viewed by just that particular nurse. Provision can be provided where the nurse can attach more evidence and send it for reconsideration. Advantages of the DSS
The main advantage of this system is the integration I accumulation of the nationwide wound care information in a single location. Such information helps in making a decision for selection of appropriate wound dressings It acts as a comprehensive database for wound care research. Since the decision support system is integrated with a learning package which is more of a wound care guideline than a latest news provider,it can be used to train staff as well as assist them with their professionaljdgement. CONCLUSION
In this research, the issues concerning the management of wounds by the nurses were reviewed and possible solution to the selection of appropriate wound dressings for given wound type was identified. The solution being a web based decision support system that helps to identi@ the appropriate wound dressing for a given wound. A nationwide survey was conducted to find out the feasibility of such a system and 96% (43) of the respondents showed interest in such a system. The paper also discussed the need for Decision Support System and the methodology and technology with which such a web based decision support system is being developed. This DSS, once fully developed, aims to reduce the confusion among the nurses in selecting appropriate wound dressings and also serve as a comprehensive guideline to wound care management.
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REFERENCES 1 C Dowsett, ‘Developing wound management guidelines for community nurses’, British Journal of Community Nursing, 2002 7(2) 62-68.
2 B M King, ‘UK Wound management; Nurses’ knowledge; Research studies’, Journal of Wound Care, July 2000 9 0 343-346. 3 I Barlow, ‘Prescribing for leg ulcers in general practice, Part 2, Journal of Wound Care, Sep 1999 8(8) 390 - 393. 4 E Boxer and C Maynard, ‘The management of chronic wounds: factors that affect nurses’ decision-making’, Journal of Wound Care, Sep 1999 8(8) 409 - 412.
5 I Barlow, ‘Prescniing for leg ulcers in general practice, Part P, Journal of Wound Care, Aug 1999 S(7) 369-371. 6 N A Bakalis and R Watson, ‘Nurses’ decision making in clinical practice’, Nursing Standard, Feb 16 2005 19(23) 33-39.
7 BC Delany, DA Fitzmauricc, A Riaz and R Hobbs, ‘Can computerised decision support systems deliver improved quality in primary care?’, BUI, Nov 13 1999 No 3 19,1281. 8 A Tong, ‘Clinical Guidelines: Can they be effective? Amanda Tong questions, NT Plus, Mar 200 1 97(9) Pg III - IV. 9 J Unsworth and H Boon, ’Developing Internet based wound care information’, British Journal of CommunityNursing, 1999 4(9) 426-435. 10 The New NHS: Modem, dependable, Department of Health, The Stationery Office, London, 1997. 1 1 R B Elson and D P Connelly, ‘Computerized patient records in primary care: Their role in mediating guideline-driven physician behaviour change’, Archives of Family Medicine, 1995,4,698-705.
12 P J Haug, B H Rocha and R S Evans, ‘Decision support in medicine: Lessons fiom the HELP system’, Int JMed Inj Mar 2003 69(Iss 2-3) 273-284. 13 A X Garg, N K Adhikari, H McDonald and M P RosasArellano, ‘Effects of computerized clinical decision support systems on practitioner performance and patient outcomes: A systematic review‘, The Journal Of The American Medical Association, Mar 9,2005 2 9 3 ( I ~10) ~ 1223-1238.
14 D Short, M Frischer andJ Bashford, ‘The development and evaluation of a computerised decision support system for primary care based upon ‘patient profile decision analysis’, Informatics in Primary Care, December 1,2003 11(4) 195-202.
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15 V J Ablaza and J Fisher, ‘Wound care via Telemedicine: The wave of the fitme’, Home Healthcare Consultunt, 1998 5(8) 12- 16. 16 W A Wilbright, J A Birke et al, ‘The use of Telemedicine in the management of diabetes-related foot ulceration: A Pilot study’, Advances in Skin and Wound Care, 2004 ISS 17,232-278.
17 P E Houghton, C B Kincaid, K E Campbell, M G Woodbury and D H Keast, ‘Photographic assessment of the appearance of chronic pressure and leg ulcerd, Ostomy Wound Management, 2000 46(Iss 4) 28-30. 18 Eccles et al’s Editorial Letter, B W , Feb 2003, No 326,394. 19 H F Clarke, C Bradley, S Whytock, S Handfield, C Van Der Wal and S Gundry, ‘Pressure ulcers: Implementation of evidencebased nursing practice’, Journal of Advanced Nursing, 2005 49(Iss 6 ) 578-590. 20 K W Thomas, C S Dayton and M W Peterson, ‘Evaluation of internet-based clinical decision support systems’, Journal of Medical Internet Research Oct - Dec 1999 l(Iss 2) E6. 21 J H Wandersee, ‘Concept mapping and the cartography of cognition’; Journal of Research in Science Teaching, I990 27( 10) 923-936.
22 P L Chang, Y C Li and S H Lee, ‘The differences in health outcomes between web based and paper-based implementation of a clinical pathway for radical nephrectomy’, BJU International, 2002 90 522-528. 23 M Leventhal, D Lewis and M Fuchs, Designing XU5 Internet Applications, New Jersey, Prentice Hall PTR, 1998.
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TREATMENT OF COTTON FABRICS WITH ETHYL CELLULOSE MICROCAPSULES R. Badulescu', V. Vivod2,D. Jausovec2and B. Voncina* 'University of Ploiesti, Romania 2Universityof Maribor, Textile Department, Slovenia ABSTRACT Microencapsulation is a process, which enables a controlled loading and releasing of active substances In textiles, the major interest in microencapsulation is currently in the application of durable fragrances, skin softeners, phase-change materials, antimicrobial agents and drugs delivery systems. The capsules can be applied to fibers as dispersion with a binder, using padding, spraying, impregnation, and exhaust or screen-printing techniques. In our research, EC (ethyl cellulose) microcapsules containing essential oils were prepared by phase separation method. Essential oils such as rosemary, lavender, and sage were microencapsulated for odor control applications; they have sedative, antibacterial and deodorant properties. The surface of the obtained EC microcapsules was smooth. The size range of the microcapsules depended on the stirring speed employed in encapsulation (350-1000 rpm). Reducing the stirrer speed increased the size of microcapsules. The oil presence in EC microcapsule has been proved by vibrational spectroscopic analysis after microcapsules dissolution in acetone or after sonication in cyclohexane. The obtained EC microcapsules were grafted onto cotton fabrics using 1,2,3,4 butanetetracarboxylic acid (BTCA). To reduce the temperature of grafting two catalysts, cyanamide and N,N'-dicyclohexylcarbodrbodiimide were used. Scanning electron microscopy was used to study the linking of microcapsules onto textile substrate and Fourier Transform Infiared spectroscopy were involved to study the formation of ester bonds between hydroxyl groups of cotton and hydroxyl groups of EC via BTCA.
INTRODUCTION In textiles, the major interest in microencapsulation is currently in the application of durable fragrances, skin softeners, phase-change materials, and antimicrobial agents [11. The preparation of microcapsules from ethyl cellulose (EC) has been reported in the literature using various methods such as phase separation, coacervation, solvent evaporation, either by addition of a non-solvent, or of an incompatible polymer [2-51. The morphology of the microcapsules greatly depended on the solvent system [6].The viscosity and concentration of EC as a wall former, ratio of EC and active ingredient, and concentration of emulsifier also influenced the properties of microcapsules [5]. Zandi and coworkers [3] studied the effects of particle size, encapsulation efficiency and morphology of different molecular weights of EC. In our research, cotton fabrics were treated with EC microcapsules containing essential oils such as Rosemary oil or limonene. Rosemary oil is used in aromatherapy and in medicine for its antibacterial and antifungal properties. Limonene is the main component of the essential lemon oil; it is widely used in perlimes and cosmetics.
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EXPERIMENTAL Materials Ethyl cellulose (EC) was purchased fiom Aldrich (viscosity 4 cP, 5 % in toluene/ethanol 80:20, extent of labeling: 48% ethoxyl). Rosemary oil was provided from Etol, Celje, Slovenia. R(+)limonene (95% sum of enantiomers) was used fiom Fluka. All other chemicals were of analytical reagent grade. Pure cotton with a mass of 140 g/m2 was used after it was first desized, scoured, bleached and mercerized on continuous production equipment.
Preparation of ethyl cellulose microcapsules EC microcapsules containing limonene and Rosemary oil were prepared as reported in patent [4]. 0.5 g sodium lauryl sulfate dissolved in 50 ml tap water was saturated with 6 ml of ethyl acetate. The pH of the aqueous phase was adjusted to 3. An organic phase was prepared by dissolving 0.7 g oil and 0.3 g ethyl cellulose in 5 ml of ethyl acetate. The resulting organic phase was poured into the previous aqueous phase under magnetic stirring. 100 ml of water was then added to the emulsion to induce diffusion of the organic solvent into the aqueous solution. After microcapsules were formed during a period of about 3-10 minutes, they were filtered on 0.45 pm diameter pore, washed by water and dried at room temperature. They were stored at 20°C. Blank microcapsules were prepared in the same manner with no oil added.
Determinationof oil content in ethyl cellulose microcapsules EC microcapsules containing oil were poured into cyclohexane and ultrasonicated for 1 min to extract the oils. The suspension was then filtered through a 0.25 pm filter to separate EC microcapsules. The limonene content was determined by FT Raman Spectroscopy. Each determination was carried in triplicate. FT-IR analysis gave qualitative information regarding Rosemary oil content in EC microcapsules. Thus, the 1730 cm-’ band was monitored. FT-Raman spectra were carried out using Perkin-Elmer spectrometer equipped with Nd:YAG laser source. Spectra were accumulated fiom 64 scans at a resolution of 4cm-’. An optical bench alignment was performed before each Raman measurements to ensure that the spectrometer was fine-tuned and the detector signa.l maximized. FT-IR spectra were recorded using Perkin-Elmer spectrometer equipped with diamante crystal for attenuated total reflection (ATR). The FT-IR or Raman spectra were smoothed and their baselines were corrected using the “automatic smooth” and the “automatic baseline correct” functions of the built-in software of the spectrophotometer. Then, the intensities of the interested peaks were measured. Scanning electron microscopy (SEM) was performed using PHILIPS XWOESEM scanning electron microscope after the microcapsuleswere coated with gold.
Treatment of cotton fabrics with ethyl cellulose microcapsules EC microcapsules were linked onto cotton via grafting with 1,2,3,4butanetetracarboxylicacid (BTCA). The mercerized cotton was immersed in treatment baths with different concentrations of EC microcapsules and B’TCA; for reduction of curing temperature the catalysts cyanamide (CA) and N,N’-dicyclohexylcarbodiimide 0 Woodhead Publishing Limited, 201 0 227
@CC) were used [7]. The wet pick up was 100%; the cloth was predried at room temperature for 24 hours and cured at llO°C for 20 and 2 minutes respectively when CA was used. When DCC as a catalyst was used the thermofixation was omitted, the esterification was expected to occur at room temperature. The treated textile material was rinsed in cold water. The weight gain of the finished fabrics was measured. The samples were dried for 4 hours at 105°C and weighed before and after finishing.
RESULTS AND DISCUSSION Preparation of ethyl cellulose microcapsules EC microcapsules containing Rosemary oil or limonene were obtained by phase separation method. According to this procedure, EC microcapsules without oil could also be produced. This could be explained due to EC interfacial activity, which stabilizes the formed emulsion. Surfactant-fiee multiple emulsions using EC as a polymeric emulsifier have already been reported by Melzer and collaborators [S]. From the scanning electron micrographs shown in Fig. 1 it is observed that EC microcapsules had regular spherical shape, the size of microcapsules varied and that the surface was porous. The size and degree of sphericity of the microcapsules depend on the stirring speed employed in encapsulation (see Table 1). Reducing the stirrer speed increased the size of microcapsules. Lower stirring speed provided microspheres with slower release rate of oil. This could be explained by an increased resistance of the dispersed phase to size reduction, since the viscosity of the dispersed phase increased as the stirring speed was reduced [9]. The yield of microencapsulation was measured by comparing the total weight of the microcapsuleswith the combined weight of the polymer and oil.
Fig. 1 SEM micrographs of EC microcapsules containing limonene oil (The stirrer speed was 350 rpm).
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Table 1. Influence of the stirrer speed on yield of microencapsulation and microcapsule diameter Oil Stirrer speed, Yield, Diameter f SLY, Rpm % pm Limonene 350 57 75i12 Rosemary oil 350 68 728 500 58 43*13 750 67 42i5.6 1000 50 201t5.1 Without 350 75 7W15 aeachvalue represents the mean f standard deviation (SD) of fifty measurements Good results in terms of recovery, shape, size distribution were obtained in the case of blank microcapsules (Table 1). The presence of oil causes deficiencies of the microcapsule recovery. In order to facilitate the encapsulation of oil, this should have a density comparable to that of the aqueous external phase and complete immiscibility with the external phase [6,9]. This could explain the increased yield microencapsulation of Rosemary oil (density 0.91 g / d ) compared to limonene (density 0.84 gd).
Determination of limonene content in ethyl cellulose microcapsules The limonene content was estimated by FT-Raman spectroscopy. FT-Raman spectra of limonene and cyclohexane are presented in Fig. 2. The FT-Raman spectrum of R(+,)limonene showed characteristic peaks at 1678 cm-' ( v of ~cyclohexene)and 1645 cm- ( V C ~of vinyl) [10,11]. In FT-IR Raman spectrum of cyclohexane there is no absorption in 1600-1700 cm" region. Thus, the limonene amount from cyclohexane solutions can be determined by monitoring the intensities of the 1678 or 1645 cm-' peaks. For calibration, FT-Raman spectra of different concentrations of limonene in cyclohexane were recorded (see Fig.3). In our study, the intensity of 1645 cm-' was correlated to limonene content in cyclohexane. There was a linear relationship. The calibration curve had the following equation y = 12.2577x+0.00955,R=0.98 (Fig. 4). Content (%) of R(+)limonene in EC microcapsules was measured using the above equation. According to the proposed method, the EC microcapsules contained 9.8*5.5% limonene.
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Raman shift cm-' Fig. 2 FT-Raman spectra of R(+)limonene and cyclohexane
llmonenelcyclohexane(qlml)
r---
I
Fig. 3 FT-Raman intensity of the 1645 and 1678 cm-*peaks of different concentrations of limonene in cyclohexane The small amount of encapsulated oil is due, probably, to porous structure of EC microcapsules. The oil content is unchanged upon storage at room temperature for 3 months.
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om--
y==12.2577*rH).00955 R4.98
, dmJ
I
O
h
001
001s
oh
L&&en%$ohexane
OinJ
(g/ml)
'
Cotton fabrics were treated with BTCA, EC microcapsules and catalyst. After the unreacted BTCA and catalyst were washed, the carbonyls retained in the fabrics existed in three forms - ester, carboxylic acid, and carboxylate anion [13,14]. In Fig. 6 the bands due to an ester carbonyl appear around 1717-1730 cm-'. However, a band in this area is ambiguous and can be interpreted either as an ester carbonyl band or a carboxyl carbonyl band [13, 141. The post treatment of finished fabrics in an alkaline solution converts the acid to carboxylate anion, which absorbs at 1570 cm-', while the ester carbonyl is left unchanged. In FT-IR spectra of alkaline post treated finished fabrics, the band intensity near 1700 cm-' decreased while the intensity of the carboxylate region centered at 1570 cm-' increased [15-161. From FT-IR spectra we have got the evidence that some crosslinking between hydroxyl grou s of EC microcapsules via ester bonds occurs as well. The presence of 1717-1722 cm-Pabsorption indicates that there are ester links between BTCA and hydroxyl groups of cellulose, hydroxyl groups of EC microcapsules, or both. The large absorption centered at 1700 cm-' is due to the carboxylic acid of unreacted BTCA. The overlapped bands at 1700 and 1690 cm-' are due to the hydrogen bonded and flee carboxylic groups of BTCA [141. The absorption band at 1737-1744 cm-' could be ascribed to the carbonyl vibration of camphor or bornyl acetate from microencapsulated Rosemary oil. From Fig. 6 it is possible to see that the intensity of this band increases when textile material encapsulated with Rosemary oil is heated on 150 "C (spectrum c). We can conclude that temperature of 150 "C is too high for the treatment of EC microcapsules and some of the oil penetratedevaporatesthrough the microcapsules wall. The curring temperature was reduced to 110 "C; spectrum a in Fig 6 indicates that some esterification occurs during the thennofixation; the intensity of 1743 cm'' band is low which indicates that there was no oil penetration through the microcapsules wall, so the thermofixation temperature of 0 Woodhead Publishing Limited, 201 0 231
110 "C is high enough for grafting of EC microcapsules onto hydroxyl groups of cellulose using BTCA.
0.30
1-
0.25
-
0.20
-
0.15
-
0.10
-
0.05
-
0.35
El .......
4000
2500
3000
3500
2000
1500
1000
wavenum b e n cm"
Fig. 5 FTIR spectra overlap of a)EC, b)Rosemary oil and c)EC microcapsules containing Rosemary oil
j'il .......
0.020 0 0 1. s_
0.010
-...........
i
1800
.
,
1780
.
l
1780
.
~
1740
.
#
1720
'
t
1700
.
t
1880
'
,
.
I880
w r v o n u m bor cm"
Fig. 6 Differential FT-IR spectra of cotton (cotton spectrum was substracted) treated with a)BTCA, microcapsules containing Rosmary oil, CA 110°C 20min b)BTCA, microcapsules containing Rosmary oil, DCC c)BTCA, microcapsule containing Rosmary oil, CA 150°C 2Omin Further EC microcapsules were grafted onto hydroxyl groups of cellulose via BTCA using DCC as a catalyst. Spectnun b in Fig 6 indicates that some ester groups were formed even when textile material was treated at room temperature. The morphology of the surfaces of the linked microcapsules via CA was examined &er curing. Fig. 7 shows SEM image of EC microcapsules linked on cotton at 110°C using CA as a catalyst. After few minutes curing the microcapsules are presented on 232 0 Woodhead Publishing Limited, 201 0
cotton and keep their shape. The EC microcapsules are stable after cold water washing, as the microphotography revealed.
,
%
,
.
,
Fig. 7 SEM microphotography of EC microcapsules' linked on cotton (CA) at llO"C2min According to previous research on the crossllnking of hydroxyl groups of cellulose a grafting reaction of EC microcapsules onto hydroxyl groups of cellulose via BTCA, where three types of reactions can occur simultaneously: the grafting of EC microcapsules via BTCA onto hydroxyl groups of cellulose, crosslinking between the hydroxyl groups of cotton and between hydroxyl groups of EC microcapsules (Fig. 8).
with BTCA and our current research, we can propose
F
Cell, EC
I I
Catabyst,
HC-COOH H2C-COOH
YOOH
0
COOH COOH
0
II CeIl-O-C-CH2-CH-CH-CH2-C-O-EC I
H2 X O O H
HC-COOH
O It
~
0
II I II Cell-O-C-CH2-CH-CH-CH~-c-O--CeB I 0 It
EC--O--C--CH2
COOH COOH I
0 II
H--CH2--C-O-EC --YCOOH
Fig. 8 Proposed grafting reaction of EC microcapsules onto hydroxyl groups of cellulose via BTCA
CONCLUSIONS This work described the cotton treatment with EC microcapsules prepared by phase separation method. The size range of EC microcapsules depended on the stirring speed employed in encapsulation. Reducing the stirrer speed increased the size of microcapsules. The oil presence in EC microcapsule has been proved by vibrational spectroscopic analysis after microcapsules dissolution in acetone or after sonication in cyclohexane. The obtained EC microcapsules were bonded to cotton fabrics through the 0 Woodhead Publishing Limited, 2010 233
grafting onto cotton fabrics via BTCA. Scanning electron microscopy and Fourier Transform lnfrsved spectroscopy were used to study the formation of ester bonds between hydroxyl groups of cotton and hydroxyl groups of EC.
Acknowledgement
This research has been supported by a Marie Curie Transfer of Knowledge Fellowships of the EC 6FP under the contract no. MTKD-CT-2005-029540Development of smart polymer surfaces (POLYSURF).
REFERENCES 1 G Nelson, ‘Applicationof microencapsulation in textiles’, Int J Pharm, 2002 242 5562 2 N Peamchob, R Bodmeier, ‘Coating of pellets with micronized ethylcellulose particles by a dry powder coating technique’, Int J Phurm, 2003 268 1-1 1 3 M Zandi, A Pourjavadi, S A Hashemi, H Arabi, ‘Preparation of ethyl cellulose microcapsules containing perphenazine and polymeric perphenazine based on acryloyl chloride for physical and chemical studies of drug release control’, Polymer Znt, 1998 47 413418 4 V Babtsov, Y Shapiro, E Kvitnitsky, ‘Method of microencapsulation‘ US Patent Office, Pat No 6 932 984, August 2005 5 M Song, N Li, S Sun, L R Tiedt, W Liebenberg, M devilliers, ‘Effect of viscosity and concentration of wall former, emulsifier and pore-inducer on the properties of amoxicillinmicrocapsules prepared by emulsion solvent evaporation’, h’Furmaco, 2005 60 261-267
6 Z-YZhang,Q-N Ping, B Xiao, ‘Microencapsulationand characterization of tramadolresin complexes’, J Control Rel, 2000 66 107-1 13 7 E L Gillingham, D Lewis, B Voncina, ‘An FTIR Study of Anhydride Formation on Heating Butane Tetracarboxylic Acid in the Presence of Various Catalysts’ Textile Res J, 1999 69(12) 949-955 8 E Melzer, J Kreuter, R Daniels, ‘Ethylcellulose:a new type of emulsion stabilizer’, Eur J Pharm Biopharm, 2003 56 23-27 9 A H L Chow, S S Ho, H Y Tong, H M Ma, ‘Parameters affecting in-liquid drying microencapsulation and release rate of cefaclor’, Znt J Pharm, 1998 172 113-125 10 D Daferera, C Pappas, P A Tarantilis, M Polissiou, ‘Quantitative analysis of apinene and $-myrcene in mastic gum oil wing FT-Raman spectroscopy’, Food Chem, 2002 77 511-515 11 M Baranska, H Schulz, S ReitZenstein, U Uhlemann, M A Strehle, H Kruger, R Quilitzsch, W Foley, J Popp, ‘Vibrational spectroscopic studies to acquire a quality control method of eucalyptus essential oils’, Biopolymers, 2005 78 237-248 234 0 Woodhead Publishing Limited, 2010
12 H Schulz, G Ozkan, M Baransh H Kruger, M Ozcan, ‘Characterisation of essential oil plants fkom Turkey by IR and Raman spectroscopy’, Vib Speck, 2005 39 249-256 13 C Q Yang, G D Bakshi, ‘Quantitative Analysis of the Nonformaldehyde Durable Press Finish on Cotton Fabric: Acid-Base Titration and Infrared Spectroscopy’, Textile Res J, 1996 66(6) 377-384 14 D M Lewis, B Voncina, ‘Durable press finishing of cotton with polycarboxylicacids. I. Preparation of thiosuccinyl-s-triazhe‘,J Appl Polymer Sci, 1997 66(8) 1465-1474 15 R Badulescu, V Vivod, D Jausovec, B Voncina, ‘Grafting of Ethylcellulose microcapsules onto cotton fibres’, Carbohydrate Polymers, in press 16 B Voncina, A Majcen Le Marechal, ‘Grafting of cotton with p-cyclodextrin via poly(carboxy1ic acid)’,JAppl Polymer Sci, 2005 %(4) 1323-1328
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MEASURING INTERFACE PRESSURE IN COMPRESSION GARMENTS FOR BURNS PATIENTS E.Maklewska, A.Nawrocki, K.Kowalski ,W.Tamowski Institute of Knitting Technology and Techniques, Poland
ABSTRACT One of the consequences of serious burns of the human body is hypertropic scam (HS). They create a lot of problems for patients not only due to disfiguration, but also as they cause itching, skin tension, limitation of limb movements. Pressing-therapy by using textile garments, called burn or compression gannents (CG),is recognized as one of the mostly successful methods of preventions. Efficiency of CG depends on the constant, uniform and determined pressure exerted by this garment on the covered body area. As hospitals do not possess appropriate measuring devices, which would enable measuring pressure on the scar exerted by the textile garment, the pressure efficiency and the appropriate fittings are estimated subjectively for a particular case. The research work presented herein, presents selected results of tests carried out with the use of a new measuring stand designed for measuring the pressure exerted by textile products used in healing therapy of hypertropic scars. The testing device was designed and built at the ‘Tricotextil’ Institute of Knitting Techniques and Technologies and was named ‘Textilpress’. On World Exhibition on Innovation, Research and New Technologies EUREKA 2006 in Brussels, which took place fiom 23rd to 28th November 2006, the test stand TEXTLPRESS was rewarded a Gold Medal.
Key words: hyperthropicscars, compression garments, pressure measurement INTRODUCTION Pressure therapy, also known as compression therapy, for scar management is an established component of a recovering burn patient‘srehabilitation programme. Pressure can be achieved through special tight-fitting compression garments (CG) or dressings made of elasticized fabrics. Elastic bandages or garments used to provide constant and equal pressure provide compression over the healed burn. This compression minimizes development of scarring and deformity caused by serious bum injury. These scars are warm, red in colour due to increased vascularity, raised due to increased collagen disposition. These types of hypertrophic scars (HS) are presented in Figure 1.
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I
I
..
.
Fig. 1. Samples of hypertrophic scars (HS) caused by serious burn injury (acc. document files injury (am. document files of Department of Paediatrics’ Surgery and Oncology, Medical University of E6&, Poland) Compression garments (CG) help to reduce bulky, thick, hard scars by pressing and flattening the scars. The tightness of a compression garment also helps to stop the itching associated with a healing burn. It also stops feeling of skin tension and prevents limitations in limb movements thus improving physical fitness [l, 2, 3, 4, 5, 61. The photos in Figure 2 show examples of using CG.
Vest with sleeves
Glove with open finger tips
Face mask
Fig. 2. Examples of using ‘burn-garments’ (acc. document files of Department of Paediatrics’ Surgery and Oncology, Medical
University of E6&, Poland) All garment-products of this type should be worn 24 hours per day, fiom 2 to 6 months, until flattening, d o u r fading and tissue softening are observed. Compression garments, should be designed so that the pressure on the protected body area with the scar would be within the range of 20 - 25 mm Hg (26.7 - 33.3 hPa). Too high, and not checked pressure during the healing period, may cause disadvantageous changes especially to small children. As hospitals do not possess appropriate measuring devices, which would enable to measurement of pressure on the scar exerted by the textile garment, the pressure efficiency and the appropriate fittings are estimated subjectively for particular case. The pressure measuring methods used hitherto are evaluated critically, and a broad literature review devoted to the methods, which allow measuring pressure exerted by garments, is presented in [7]. Often the measurements are performed by means of the electro-pneumatic method. The research work presented herein, presents selected results of tests carried out with the use of a new measuring stand designed for measuring the pressure exerted by textile products used in healing therapy of hypertropic scars. The testing device was 0 Woodhead Publishing Limited, 201 0 237
designed and built at the ‘Tricotextil’ Institute of Knitting Techniques and Technologies’ (Poland) and was named ‘Textilpress’. To underline the difficulties of the measurements, it should be emphasized that under real conditions the pressure gauge must measure pressure values within the range of atmospheric pressure changes. The aim of the article, presented herein, is a description of the new test device named ‘Textilpress’designed for measuring the pressure exerted by textile products used in the healing therapy of hypertropic scars. The ‘TeXtilpress’ device has been used for verification of the often used method of designing and manufacturing ready-made compression garment products. This method is based on a constant reduction of the circumferences of knitting elements of garment by 10 - 20 percent in relation to the body’s circumferences[ 6 ] . INVESTIGATIONMETHODS Test stand description The pressure measurement, achieved by use of the ‘Textilpress’ device, is an indirect measuring method, which is based on the Laplace Law. Laplace Law has been widely used to calculate the pressure delivered to a cylinder of known radius by a fabric under known tension. However, this Law was originally developed by Laplace in 1806 to explain the surface tension phenomenon in liquids and their ability to form droplets or soap bubbles [6].The Laplace Law is illustrated in Figure 3 and by equation (1). Texttle band
erndl
sure P
Fig. 3. Scheme illustratingthe Laplace Law
p = -T
R
where: P - pressure, the normal force per area unit, T -tension expressed as force per width unit of the pressure band (T=F/w), R - radius of cylinder curvature,
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X 1.111“,11*
dNllll.,”
[a”.
411,,
Fig. 4. Measuring matrix; a) scheme, b) general view; 1) ‘open’ gauges for circumference force measuring, 2) ‘closed’ gauges for curvature measuring, 3) additional curvature gauges The basic element of the test stand Textilpress, with identified locations of sensors are shown in Figure 4. The measuring matrix is equipped with two kinds of measuring tensometric sensors called ‘closed’ and ‘open’. The ‘closed’ gauges are for determining the radius of curvature R of the circumference tested. The ‘open’ gauges measure the tension T. The measuring matrix includes three sets x 6 (4 ‘closed’+2’open) = 18 gauges which enable the determination of tension and the curvature in 3 independent circuits in the measuring field. Additional curvature gauges are placed parallel to the axis of the compression band and allows corrections of the pressure measurement if the tested body is not an ideal cylinder. The pressure distribution at the basic points, and the approximated pressure distribution between these points are accepted as the measuring results, this amounts to 25 points. An example of recorded test results for testing with Textilpress is shown in Table 1. The dimensions of the measuring field are 70 x 50 mm. Technical parameters of the ‘Textilpress’device are listed below: - Pressure measVing range: 0 to 70 mm Hg lo%, - Measuring resolution: f 1 mm Hg, - Range of the tension T: 0 to 200 N/m, - Range of the curvature radius 25 to 200 mm, - Minimum radius of bending the matrix: 20 mm (exceeding this value m a y cause damage to the matrix
*
A view of the ‘Textilpress’ device is shown on the photos in Figure 5.
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1
Fig. 5. View of the ‘Textilpress’ measuring stand during measuring; 1) textile compression band, 2) measuring matrix placed uader the compression band, 3) cylinder, 4) cylinder holder, 5) strain gauges amplifier, 6) computer. Investigation procedure The investigations described in this paper concern the pressure measuring under textile bands placed on a model representing selected parts of a human body with pre-set circumferences. For this purpose, rigid cylinders were prepared, covered by a layer of neoprene which simulated the susceptibilityof human skin. Before performing the tests the measuring stand should be calibrated. The calibration of the radius of curvature and the pressure is carried out with the use of cylinders with predetermined dimensions, for tensions of 28 N/m and 170N/m. In order to make measurements, the tested band should be placed on the cylinder with the matrix fastened to it so that the test can be carried out (Figure 5). A protocol example of recorded test results for a compression band placed on a O.lm diameter cylinder is presented in Table 1. These show the values of pressure and the diameter of curvature recorded in 25 points. Average pressure and diameter values for tested band are also given. Table 1. An example of recorded test results report for testing with use of Textilpress Information: Test In DT 15:26:29 Pressure, hPa 16 24 32 27 22 27 23 16 24 32 27 23 16 24 32 16 24 27 23 32 27 23 15 24 32 Average pressure value = 24,3 S = 5,4 Max = 7,9 Min = -9,O V = 22,2%
Curvature diameter, mm 114 114 114 114 114 114 114 115 114 114 113 114 115 114 113 115 115 115 114 113 118 117 116 115 114 Average diameter value = 114,4 S= 1,O M a = 3 , 1 Mh=-1,4V=O,9% -
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TEST MATERIAL For testing purposes a series of commercial compression bands used in hypertropic scars therapy, made from warp-knitted fabrics were used. The dimension of circumferenceGo of the bands was calculated according to equation
Go - circumference of the band, in fiee state [cm] GI - circumference of the cylinder [cm] E - relative elongation of the bands and is equal 0,l The dimensions of the bands are listed in Table 2.
TEST RESULTS AND DISCUSSION The results of pressure measurement under the tested compression bands, carried out with the use of the Textilpress' test-device are presented in Table 2 and in Figure 6. The maximum and minimum pressure recommended in compressive therapy was marked in Figure 6, as Pmm=33.3 hpa and P,i, = 26.7 hPa respectively. Table 2. Dimensions of the bands and test results of the pressure exerted by compression bands LP
Cylinder denotation
2
Cylinder circumferenceG1 [ml Band denotation
4 5
Bandcircumference Go,[ml Relative elongation Pressure, [hpa]
1
C
D
E
F
G
H
I
0,19
028
0,35
0,41
0,50
0,66
0,82
0,85
BT
CT
DT
ET
FT
GT
HT
IT
0,17
0,25
0,32
0,35
0,45
0,60
0,73
0,75
0,l 27,5
0,l 27,l
0,l
0,l 22,l
0,l
24,4
19,9
0,l 18,4
0,l 16,2
0,l 16,2
*
*) The cylinders C, E, and I are pattern cylinders, for calibrations
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35
-
30
9 f t 20 25
h
15
10 0.19
0,28
0,35
0 Pressure under bands
0.41
0,66 0.82 0.85 Cylinder circumference G l [m]
0,5
---- Pmax -Pmin
Fig. 6. Graphical illustration of the test results of pressure measuring under the bands of both series I and I; the maximum and minimum values of the pressure recommended in pressing therapy have been marked in the figure. An analysis of the results of pressure measuring under compression bands manufactured by the commercial producers of compression products and placed on appropriate cylinders, indicates that the pressure value exerted by those bands, decreases with the increasing the cylinder diameter. Almost all of pressure values are below of recommended pressure minimum Pmin =26,7 Wa.It should be underlined, that the relative difference between band circumferences of this series and the corresponding cylinder circumferences has a constant character, and is equal 0.1.
CONCLUSIONS The investigationsdescribed in this paper, indicate that the ‘Textilpress’test-device may be used for measuring pressure exerted by compression bands on the cylinder surface. In order to estimate the pressure exerted on a particular body part with the shape close to a cylinder, a measurement should be carried out on a cylinder with a circumference similar to that of the selected part of the human body. Theoretically, the matrix may be placed also directly on the body, but in reality the realization of such a measuring test would be objectively difficult. The object with the matrix placed on it, should be motionless, that for example by testing children would be rather impossible. The investigationscarried out, demonstrate that designing method based on using a constant difference value between the compression band circumference in h e state and the circumference of the model part of the body is erroneous and does not provide the expected level of pressure value. It seems, that this difference should be depended on the circumference of the model part of the body. Additionally the pressure under garment should be checked by testing with measurement device. On World Exhibition on Innovation, Research and New Technologies EUREKA 2006 in Brussel, which took place fiom 23th to 28th November 2006 the test stand TEXTILPRESSwas rewarded with a Gold Medal.
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Acknowledgment The investigation presented in this paper was carried out as part of the research project No.4T08E05425 financially supported by the Polish Ministry of Scientific Research and Information Technology. The authors wish to thank Prof. Ewa Andrzejewska, MD., Ph.D and Wojciech Kuzahski MD., Ph.D. (Department of Paediatrics’ Surgery and Oncology, Medical University of L6di) for contribution in this research work.
REFERENCES 1 B Lamberty, J %taker, ‘Prevention and correction of hypertrophic scarring in posburns deformity’, Physiotherapy, 1981 67 1,2-4.
2 H L i e s , et al. ‘Historical notes on the use of pressure in the treatment of hypertrophic scars or keloids’ Burns, 1993 19( 1) 17-21. 3 F Reno, P Grazianetti, M Cannas, ‘Effects of mechanical compression on hypertrophic scars: prostaglandin E2 release’, Burns, 2001 27(3) 215-217. 4 W Williams, D Knapp, M Wallen, ‘Comparison of the characteristics and features of pressure garments used in the management of burn scars’, Burns, 1998 24 329-335. 5 H P Giele, K Liddiard, F M Wood, ‘Direct measurement of cutaneous pressures generated by pressure garments’, Bums, 1997 March 2312, 137-141.
6 L Macintyre, et al, ‘The study of pressure delivery for hypertrophic scar treatment’, int con€ Healthcare Medical Textiles, Bolton (UK),July 2003. 7 A Finnie, ‘Interface pressure measurements in leg ulcer management’, British J of Nursing, 2000 23 Mar-Apr 12 9(6 Suppl):S8-10.
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PSYLLIUM: CURRENT AND FUTURE APPLICATIONS R Masood and M. h4iraftab, Institute for Materials Research and Innovation, The University of Bolton, Deane Road, Bolton, BL3 5AB,U.K. ABSTRACT Psyllium, also referred to as ispaghda, is derived from the hush of the seeds of Plantago ovata. Psyllium is a natural, water-soluble, gel-reducing material and has been traditionally used in China and India as herbal medicine to treat bladder problems, high blood pressure and for treatment of skin irritations. Swelling and gelatinous mass properties of psyllium make it suitable for specific drug delivery systems as well as absorption.Psyllium has also been reported to possess cholesterol-loweringabilities as well as wound healing properties. It is being utilized as part of many colon cleansing programmes and even in the prevention of colon cancer. In this paper an imdepth review will be made on current uses and application spectrum of psyllium. The potential use of psyllium as a wound healing aid and its possible application in wound dressings will also be discussed. INTRODUCTION Natural substances have made a great contribution to the health and well being of human life. They are derived from natural sources such as plants, animals and minerals (1) and have played a vital role in the development of modern civilizations. They provide food, clothing, shelter, and medicine. Natural materials are also valued for their medicinal, aromatic and savoury qualities. They possess variety of potentially active substances wlich help in maintenance and management of human body health. Naturally sourced medicine is a major component in all indigenous people’s traditional medicines and a common elements in Ayurvedic (Hindu), Chinese, Ancient Greek, Unani (lslamic), homeopathic, naturopathic, traditional, oriental systems. In the early 1 P century, when methods of chemical analysis first became available, scientists began extracting and modifying active ingredients from natural sources. They discovered and developed totally new versions of these plant compounds and begun the transition from raw herbs and natural substances to synthetic pharmaceuticals. The active use of natural materials thus declined in favour of synthetic pharmaceuticals (2). However, natural materials have again enjoyed a great reappearance in the human health management due to recent environmental concerns, increasing public dissatisfaction with the cost and acute toxicity of synthetic medicine. The use and search for drugs and dietary complements derived from plants is now a growing industry and scientists are continually trying to develop novel ways of alleviating ills and finding new treatments for chronic diseases based on plant extracts. The world health organization estimates that 80% of the world population are today giving more importance to natural medicine in primary health care control. Natural substances like psyllium seeds, aloe Vera, oats, guar gum, chitosan and alginate are found to be u s e l l in treating heart disease, wound infection control, p i n relief, asthma treatment and other health related problems. Major pharmaceutical companies are currently
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conducting extensive research on plankbased materials for possible new generation of medicines and applications.
PSYLLIUM PLANT Psyllium, scientifically known as plantago ovata has gained a reputation as a natural medicinal plant. Psyllium is the common name used for several members of the plant genus Plantago and Plantago ovata, Psyllium husk and Ispaghula husk are other generic name for this imperative plant. The genus Plantago has more than 200 species(l0) which is grown all over the world but P. ovata and P. psyllium are produced commercially in several, American, South Asian and European countries as a major seasonal crop due to its seed mucilage, pharmaceutical, cosmetics and food grade properties. The actual plants of psyllium grows up to 15 cm tall and is covered in fuzzy, white hair at right angles to the stems and leaves. The leaves are narrowly linear, basal and green. The leaves put up spikes of small flowers that mature into seedpods. The seeds are small (1.5-2 cm) and brown or reddishbrown. Seeds of this plant constitute a large amount of mucilage and albuminous matter. The seed are dried and crushed to separate the husk by winnowhg (3).
Psyllium
Psyllium Seed
Psyllium Husk (99% Pure)
India is the largest grower of psyllium and provides about 85% of the psyllium available in the world market. America is the world largest importer of raw psyllium seeds and its other by-products and as much as 6Oy0 percent of its imported psyllium is used by pharmaceutical and food industries (4,5,6,42).
HISTORY Psyllium has been known in the history well before the birth of Christ and has been reportedly used for different medicinal purposes. It has been known by the Chhese as long ago as 250 BC both for the plant and its seeds. Psyllium plant has also been popular for its excellent bio-medicinal properties in early days of English history and has been called the "mother of herbs" in Anglo Saxon poems. The seeds have also been used in Europe for intestinal health since the 16th century (5). The early English colonists took psyllium plant to North America as one of their favourite healing material with them and has since been called bythe Native American as "white man's foot" as it is often found growing along well-trodden foot paths(7). The indigenous Americas adopted many of the traditional European uses of this beneficial herb. They also used the plant to draw out the poison of rattlesnake bite, to soothe rheumatic
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pains, as a poultice to treat battle wounds, and as eyewash. They would also use the fresh young leaves and seeds in their diet. Psyllium use has also been found in Ayurvedic medicine (Hindu) and Unani (Islamic) medicine prescription more than a thousand year ago for the treatment of digestive tract problems (6,8).
TRADITIONAL FOOD APPLICATIONS Psyllium has been used in wide variety of traditional food applications. It has been mixed in water, often with sugar to create a cooling drink (8). It has beenmixed with fruit extract, like coconut water, orange and prunes juice, and sometimes it has been mixed in a lieu of narrow roots into a konjee, an Indian beverage (7). Psyllium has also been used as an ingredient in making of chocolate and in jellies, as confectionary base with other ingredient such as sugar and cardamom (1 0). Nadkarni et al (8) also reported on its use with curds and rosewater and in sherbets and as thickening agent. Psyllium gum has the ability to prevent crystallization of sugar and it has been reported to be used in many dairy products. It has been used as cream stabilizer and it provides Uniform, smooth creamy structure to the ice cream and maintains this structure during ice thaw cycle. A current application in this context is manufactured by Meer Corporation which makes psyllium based stabilizers marketed as Merecol IC 01). Psyllium has also been used as dietary fibre in cereals. In USA; at least three r e a d m e a t cereals have included psyllium as a component since 1989 (12).
PHYSIOCHEMICALPROPERTIES OF PSYLLIUM Psyllium is a hydrophilic material in nature and is well known for its water uptake properties, gelling capabilities, soluble and insoluble fibre contents and surface structure. It is a natural polysaccharide and contains high percentage of hemicelluloses. It has similar molecular constituents to other naturally sourced polysaccharides e.g. alginate, chitosan, guar gum, and has more or less similar physiological functions. Psyllium is not 100% water soluble polysaccharide like alginate and guar gum. The fibre consists of 35% of soluble and 65% of insoluble polysaccharides (4). The research studies made so for on examination of psyllium gelling behaviour are not adequate to fully understand and characterise its molecula structure. Methylation and partial hydrolysis by acid and alkali bas shown that psyllium contains highly branched acidic arabinoxylan with xylan backbone having both (14) and (1-3) linkages and majority of residues in the xylan backbone are variously substituted at 0-2 and 0-3 with arabinose, xylose and aldobioronic acid identified m galactopyransyluronicacid (13). Kennedy et al(14) have also studied its physical and chemical properties and have found that it is composed of Larabinose, D xylose D-guIucronic acid and galactouric acid units (arabinoxilans). The figure below depicts proposed consensus structure of arabinoxylanof Psyllium (13).
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Fig 1. Psyllium is an excellent water absorber when it comes into contact with water; it swellsand forms a smooth bulky mass. The excellent water absorption properties shows that psyllium has numerous hydroxyl (OH) sites for water molecules to bond with and has been reported (4,15,42) to have water absorption capacity in excess of 50 times its original wei&t. Psyllium is a bulk laxative agent and has excellent gelling properties. Psyllium mucilage contains mixtures of acidic and neutral polymers of carbohydrate, sugars and hence strong tendency to gel. The psyllium gel has been extracted by using diffelent extraction methods that give gel products with different properties for different uses. Laidlaw et al (16) extracted the psyllium mucilage content from whole seeds with the help of cold and hot water. A strong alkaline substance has been used for the extraction of psyllium gel, Kennedy et al (14) treated the psyllium husk with 1.2MNaOH, Haque et al (17) used 2.5 M of NaOH to extract the fraction gel from the husk at ambient temperature. The extraction methods of gel fraction from psyllium have been used at laboratory scales and results presented are not sufficient to obtain high yield or good quality of psyllium gel which can lead to commercial production and/or to be used in other biological processes. Therefore, further research studies are required l~extract gel fraction of high yield and good quality on industrial scales. Psyllium also has the ability to bind large amounts of metals in solution because it consists of branched polysaccharides. These polysaccharides contain polyhydroxylic and carboxylic groups which react with metal ions to form a metal containing hemicellulosic complex of high stability. Roger et a1 (18) made comparative study of the iron binding properties of psyllium, lignin and cellulose by varying pH, temperature and concentraticns. They found that psyllium showed greater iron binding capacity, even at very low concentrations, and various pH conditions and temperatures than those needed for lignin and pure cellulose.
RECENT MEDICAL APPLICATION OF PSYLLIUM Psyllium plays an integral part in medical and human health management.It has been used as a safe and effective laxative and can be taken internally as dietary supplement because of its low acute toxicity (4). It has been found helpfid in maintaining the health of the
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digestive system, and has significant value in the prevention of cardiovascular disease, cancer, diabetes and other ailments (19). Coronary heart diseases are the main cause of death in the US and the Western world. The factors involved for heart disease include age, high blood pressure, smoking, diabetes mellitus and high cholesterol levels. Fibre rich dietary foods have been found to be u s e l l in maintaining blood glucose concentration, serum cholesterol as well as stabilizing insulin levels required to stimulate glucose uptake into body tissues. Psyllium as a dietary supplement has been found helpful in maintaining the health of the digestive system, and has significant value in the prevention of cardiovascular disease, diabetes and other ailments (20,21). Psyllium has also been found to be effective in controlling cholesterol levels in the body and postprandial serum lipoproteins, which are the main cause for risk of Coronary Heart Diseases (CHD). In humans, psyllium and guar gum appear to be the most effective cholesterol-lowering soluble fibres (22). In 1998, the Food and Drug Administration (FDA) gave permission to allow food manufactures to make a health claim on the packaging of food products containing psyllium. The claim reads: "Ekting soluble fibre h m foods such as psyllium as part of a diet is low in saturated fat and cholesterol". Recent scientific research studies have also revealed the important role of psyllium in controlling cholesterol levels in tbe human body, Anderson et a1 (23) have reported that psyllium containing low fat diet can possibly lower the serum cholesterol by 4% and lowdensity lipoproteins (LDL) cholesterol by 7%. They also reported that beneficial effect of psyllium fibre on glucose serum and cholesterol levels varies accordng to the dosage and period used. In another pilot study conducted by seyed et a1 (24) also it was found that psyllium in diet helped to reduce cholesterol or LDL while having no significant affect on the high-density lipoproteins O L ) cholesterol. Nummus animal and human studies have also been utilized to identify mechanisms for psyllium mediated cholesterol reduction (4). Human stool examinations studies have shown that there is an increase in bile acid excretion after psyllium use and increases in lile acid may help to decrease fat absorpticn (25). The reduction in fat absorption has helped in lowering cholesterol levels which decreases the risk for heart disease and strokes. The use of psyllium helps the human body in improving glymeric and lipids control, and reducing the risk factors involving in diabetic complications(26) like poor wound healing, higher risk of infections, and many other problems involving the eyes, kidneys, nerves, and the heart. Constipation is a common medical problem all a r m d the world and it can happen at any age. It is basically acute condition in which bowl movement occur less than usual. The research studies have shown that psyllium can help to relieve constipation. The use of psyllium to relieve constipation is standad practice in Asia, Europe, and North America. Psyllium is believed to speed the passage of stool through the digestive tract by softening the stool and attracting water thereby producing more bulky stool, which stimulates the transit of waste through the gastrointestinal tract (4,27,28 ). It also helps to reduce chances of infection and probably reduce the development of haemorrhoids (29). Psyllium has also been found helpful in preventing autointoxication (30) which results in the re-absorption of toxins into the bloodstream. It helps to relieve the problem by removing the toxins when used over a period of time. It can help with any disease by protecting the colon and preventing toxins h m being absorbed into the blood. The use of psyllium is also economical and effective alternative to conventional treatment of chronic diarrhoea. It has m side effects on human body (22).
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The extraction of toxin material from human body is also important in good health practices. The major chronic diseases have great concern with toxicity of the body. Human body is constantly exposed to handid agents through diet, air supply, and other channels. Toxic agent’s presence in human body creates irritating and/or harmfd effects and stress human body biochemical or organ functions. They damage the body’s natural weightcontrol mechanisms and contribute to weight gain of body (30). Psyllium has also been found helpful in binding and reducing the absorption of dietary fat, which can help with weight control (4,3 1, 32). Psyllium promotes the production of short chain fatty acids, which in turn result in a more acidic colon and helps to increase the growth of friendly bacterial. This also facilitates detoxification and boosts body natural defences against fatal diseases (4,29). Psyllium use as poultice (psyllium mixed with milk and turmeric powder) for minor scrapes is considered a standard practice in old and current Indian culture. Psyllium is also known to sooth and protects inflamed cell membranes. The recent research stdies carried on wound healing properties of psyllium has reported that psyllium contains Mucopolysaccharides which are useful for wound cleansing and wound healing. These mucopolysaccharides also limit scar formation on human skin (33).
OTHER APPLICATIONS OF PSYLLIUM Psyllium has attracted an increasing amount of interest to be used in different biomedical applications in the last two decades. The inherent ability of psyllium to absorb water and its gelling properties has maximized the value of psylliun incorporation in varieties of food formulations and other applications. The psyllium preparations with proper physiological functions are also high in demand due to FDA approval to include health claims of reducing heart disease. Numerous studies (13, 14, 15, 16, 17) have been made to improve psyllium physical and chemical properties and to maximize the use of this highly useful material. Yu et al (1 5) have studied reaction of solid state enzymes on functional properties of psyllium seed husk and observed that modified psyllium showed improved gelling properties, improved dispersing effect and more desirable sensory properties and decreased water absorbing capacity. Modified psyllium still contains soluble and insoluble fiber with fewer undesirable properties. Kennedy et a1 (14) and Fischer et a1 (13) have developed an efficient, reproducible process for alkaline extraction and fractionation of polysaccharide from husk which can be useful for further biological studies. Psyllium has the capability to be used in the process of biesorption of heavy metals, like other gel forming material such as alginate, guar gum and has been reported to be good as flocculants for textile, sewage and tannery wastewater treatmenti (34). Mishra et a1 (35) have also studied psyllium mucilage for dye removal from textile effluent and reported that it is one of the simplest and most efficient ways of textile effluent treatment both h m an economic and technical point of view. It shows that psyllium can be used to developan efficient, stable and biodegradable flocculants for the treatment of industrial effluents and minerals processing. Given psyllium’s strong metal binding ability and its possible role in uniform dispersion of the ions and their subsequent release under suitable conditions, it could be particularly beneficial to systems including silver and copper ions which are popular with antimicrobial fimctionalities. Singh et a1 (37) have studied psyllium potentials in
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developing novel formulation for the therapeutic agent’s delivery and found it usell. The excellent gel forming and mucilaginous properties has also confirmed the psyllium possible use with other gel-forming materials as an active enter absorbents for removing toxins, radio nuclides and also in cosmetology for preparationof non-fatty ointments. Psyllium has been found to be more cost effective gelling agent as well as having superior propertiesto agar in vitro production of plant tissues and microbial culture growth. Psyllium is also environment friendly and can be easily disposed of due its biodegradability (38,39,40) It is well known that blending is effective and convenient method to improve performance of polymer materials (41). The active psyllium gel hctionation and enzyme modification studies have shown that psyllium can possibly be modified into other biologically active materials. Novel biecomponent fibres can be developed with optimized water absorption and tensile properties by possibly fusing psyllium with other fibre forming biomaterials. The high degree of flexibility of psyllium gel c8n be utilized to meet specific requirements of current biological, medical and industrial applications. The psyllium gelling time, gel strength, stability, and degradation rate can also be modified to the required applications. Psyllium strong gelling properties may also find use in several biomedical areas i.e. implantation as a space filling material, coating of medical devices, delivery of active substances, cell entrapment, wound healing, as we1 in tissue engineering applications.
CONCLUSION In this brief review, psyllium as a plant and a herbal medicine possessing highly varied and rather unique physiochemical properties has been examined and its worldwide use and application potentials from ancient days to current times has been explored. Given the renewed interest in all natural and naturally derived herbal treatments, psyllium in particular is ideally placed for serious considerations and commercial exploitation within the context of modem technologies and the experience accumulated through longterm exploration of synthetic materials. The inherent properties associated to this natural material could be designed and engineered such that functional requirements, when used singularlyor in harmony with other materials, are fully controllable and highly prescriptive. REFERENCES 1 B P Corbman, Textile, Fiber To Fabric, Sixth Edition, McGraw-Hill Inc. 1983 Pages 245-305.
2 S Gottlieb, ‘The Future o f Medical Technology’, The New Atlantis, Journal of Technology and Sociev, Spring, 2003. 3 Psyllium Husk-for Healthier Life http://www.psylliumhusk.co.uW 4 ‘Plantagoovata (Psyllium) Monograph’, Alternative Medicine Review, 2002 7(2).
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5 C Hanrahan, Plantain, Encyclopedia of Alternative http://~d~cles.com/p/articles/mi_g2603/is~OOO5/ai~26O3OOOS94
Medicine
6 Alternative Medicine, Psyllium (http://www.alternativemedicine .com/common/adam/DisplayMonograph.asp?storelD=O2A D6 lFOOlA74B5887D3BD 11F6C28169&name=ConsSupplements~Psylliumcs)
7 M Grimm, Plantain: An herb for our “unbalanced era” September 2006 (http://www.fremontcountyvoices.com/col~tche~plan~Sept2006.h~~
8 K M Nadkami, ‘Sustainable utilization of gum and resin by improved tapping technique in some species’, The Indian Materia Medica. 1927 Bombay, India. 9 The Wealth of India, CSIR (Council of Scientific and Industrial Research, New Delhi), 8 84-94 1969 New Dew, India. 10 M K Dhar, ‘Plantago ovata: genetic diversity, cultivation, utilization and chemistry Plant’, Genetic Resources, 2005 252-263 Cambridge University Press. 11 Scott Hegenbart, 1990 Ad, Prepared Foods, August 1990.
12 FDA Consumer, Petitions necessary for psyllium use in foods, Look smart, Findarticle Dec-Jan 1989 (http://findarticles.com/p/articles/mi-mt37O/is-nlO-v23/ai-83 10001). 13 Fischer et al, ‘The gel-forming polysaccharide ofpsyllium husk (Plantago ovata Forsk)’, CarbohydrateResearch, August 2004 339 2009-2017. 14 J F Kennedy et al, ‘Structural data for the carbohydrate of ispaghda husk ex Plantago ovata Forsk’, Carbohydrate Research, 1979 75 265-274. 15 Yu et al, ‘Enzymatic modification to improve the water-absorbing, and gelling properties of psyllium Food Chemistry’, 2003 82 Issue 2 243-248. 16 R A IAdlaw and E G V Percival, ‘Studies of seed mucilages. Part V. Examination of a polysaccharide extracted from the seeds of Plantago ovata Forsk by hot water’, J of the Chem SOC.1950 528-534. 17 I U Haque et al, ‘Lipid-lowering for the prevention of coronary heart disease: what policy now?, Clinical Science, 1996 91 399-413. 18 R Fernandez et al, ‘Component of fibers bind Iron in Vitro’, The American J of Clinical Nutrition , 1982, 100-106. 19 C W Kendall, ‘The health benefits of Psyllium’, Canadian J Dietetic Practice and Research, 2004 65(3). http:llwww.ke~og~~tio~com/files/2004%2OFall%2ODCIns~Psyllium.pdf
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20 A Gaw, ‘A new reality: achieving cholesterol lowering goals in clinical practice‘, Atherosclerosis Supplements, 2002 2 5- 1 1. 21 AHA Nutrition Committee Report, ‘Rationale of the diet-heart statement of the American Heart Association’, Arterioscler 77zromb. Vmc.Biol. 1982 2(2), 177-191. 22 J A Story, ‘New insight into the dietary fibers’, Canadian J of Dietetic Practice and Research, 2003 64(4). 23 J W Anderson et al, ‘Cholesterol-lowering effects of psyllium hydrophilic mucilloid for hypercholesterolemic men,’ Arch Intern Med, 148 Issue 21988 Page 292-296. 24 S A Ziai et al, ‘Psyllium decreased serum glucose and glycosylated haemoglobin significantly in diabetic outpatients’, J o f Ethnopharmacology, 2005 102(2) 202-207. 25 A L Romero, K L West, T Zern, M L Fernandez, ‘The seeds fiom Plantago ovata lower plasma lipids by altering hepatic and bile acid metabolism in guinea pigs’, J of Nutrition, 2002 132(6), 1194-1198. 26 Anderson et al, ‘Effects of psyllium on glucose and serum lipid responses in men with type 2 diabetes and hypercholesterolemia’, Zhe American J o f Clinical Nutrition, 1999 466473. 27 Fernando, ‘Nutritional care of the patient with constipation’, Best Practice & Research Clinical Gastroenterology,2006 20(3) 575-587. 28 Alternative medicine psyllium. (http ://www.alternativemedicine.com/common/adam/DisplayMonograph.asp?storeID==O2A D6 lFOOlA74B5887D3BDI1F6C28169&name=ConsSupplements~PsylIimcs). 29 B Levy, 1998.New FDA Regulations on Antioxidants and Psyllium Seed. HerbClip 060388.Austin, TX: American Botanical Council 30 Morita e l al, ‘Psyllium shifts the fermentation site of high-amylose cornstarch toward the distal colon and increases fecal butyrate concentration in ats’, The J of Nutrition, 1998 128 2081-2089. 3 1 N Washington et al, ‘Moderation of lactulose-induced diarrhea by psyllium: effects on motility and fermentation’, Am J Clin Nutr, 1998 67 3 17-32 1. 32 C D Meletis, ‘Alternative & complementary therapies cleansing of the human bdy:’ A daily essential process Aug 2001,7(4)196 -202.
33 W Westerhof et al, ‘Mucopolysaccharides from psyllium involved in wound healing’ Brief Article, Alternative Medicine Review, June 2002.
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34 B Singh et al, ‘Metal ion sorption and swelling studies of psyllium and acrylic acid based hydrogels’, Carbohy&ate Polymers, 2006 64 50-56. 35 Mishra et al, ‘Flocculation behaviour of model textile wastewater treated with a food grade polysaccharide’, J o f Hazardous Materials, 2005 118 2 13-217. 36 B Singh et al, ‘The release dynamics of model drugs fiom the psyllium and Nhydroxymethylacrylamidebased hydrogels’, International Journal of Pharmaceutics, 2006 325 15-25. 37 B Singh et al, ‘Psyllium as therapeutic and Intl J o f Phannaceutics, 2007 334 1-14.
drug
delivery agent‘,
38 S Sahay, ‘The use of psyllium (Isubgol) as an alternative gelling agent for microbial culture media’, World J of Microbiology and Biotechnology, 1999 15(6).
39 Jain et al, ‘Isubgol as an alternative gelling agent for microbial culture media’, J of Plant Biochemical Biotechnology, 1997 6 129-1 31. 40 R Jain and S B Babbar, ‘Guar gum and Isubghol as cost-effective alternative gelling agent for in vitro multiplication of orchid’, Current Science, 2005 88(2) 12-17. 41 Mirahb et al, ’Alginate fibres modified with unhydrolysed and hydrolysed chitosans for wound dressings, Carbohydrate Polymers’, 2004 55( 1) 65-76. 42 Herbalism, Wikipedia, the fiee encyclopedia,
(http://en.wikipedia.org/wiki/Herbal-medicine) 43 Psyllium, Wikipedia, the free encyclopaedia,Available at (http://en.wikipedia.org/wiki/Psyllium)
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PART IV
BANDAGING AND PRESSURE GARMENTS
BANDAGING AND PRESSURE GARMENTS: AN OVERVIEW S. C. h a n d MBE Institute for Materials Research and Innovation, University of Bolton, Bolton, UK
INTRODUCTION Bandage fabrics, which are mostly used outside the human body, are designed to perform a very wide variety of specific functions depending upon the medical requirement. In the simplest form, they may be used to hold the dressing in place over the wound, but most modem bandages and stockings are designed for the treatment and management of specific wounds or diseases, such as post bums hypertrophic scarring, varicose vcins, deep vein thrombosis @VT), venous leg ulcers and many other surgical requirements. The history of bandages can be traced back to the ancient Egyptians who used simple woven fabrics, often coated with adhesives, resins and other medicaments as dressings to aid wound healing. Hippocrates is the first known medical source who described the relationship between venous disorders and leg ulcers (1).
CAUSES OF VENOUS DISORDERS The major causes of venous disorders are: a) inefficient or non-functioningof valves in veins; b) inefficient or non-functioningof foot pump andor calf muscles; c) pooling of venous blood in veins; d) damaged or swollen veins (varicose veins); e) blood clots in veins (deep vein thrombosis) DVT; and f ) lack of movement such as prolonged sitting, or standing, confinement to bed for long periods, lack of exercise etc. (2). For an excellent review and understanding of the causes and diagnosis of venous leg ulcers, readers are referred to this source (3).
FACTORS WHICH DETERMINE SUB-BANDAGE PRESSURE The pressure developed beneath any bandage is governed by the various factors combined into a single formula derived from the Laplace equation, as follows:
P = (nv x 4620) + C W where: = sub-bandage pressure (mmHg), T = bandage tension (kgf), N = number of layers applied, C = circumference of the limb (cm), and W = bandage width (cm). It must be pointed out that the constant value of 4620 was initially calculated as 4630, and subsequently changed to the value given in the formula. Sub-bandage pressure is therefore directly proportional to bandage tension and number of layers applied, but inversely proportional to the radius of curvature or limb circumference and the width of the bandage. It is common to apply a compression bandage with a 50% overlap, which produces two layers of fabric and generates a pressure twice that produced by a single layer.
P
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Other methods of applications, such as single layer in the case of post bums hypertrophic scarring, or applying a bandage in the figure of 8 would generate different sub-bandage compressions. Most legs, however, are not circular in cross-section. Consequently, the pressure applied by a bandage will vary significantly around the circumference at any given point on the leg. High sub-bandage pressures will be found over bony prominences such as malleolus (ankle bone) and tibial crest (shin). For this reason, a padding bandage (orthopaedic wadding) should be applied to the leg prior to the application of a compression bandage to increase pressure over concavities and decrease pressure over bony prominences. The aim should be to import to the leg a circular cross-sectional profile in order to achieve consistent levels of compression. Care must be taken to ensure that bandages do not slip or become displaced as this w ill lead to the formation of multiple layers, which, in turn, may produce localised areas of high pressure (4,5). Padding bandages also provide cushion and reduced pain to the patient after the application of compression therapy.
CLASSIFICATION OF COMPRESSION BANDAGES It is well established now that different diseases or medical conditions require different levels of compression for their efficient treatment and management. For instance, for the treatment of varicose veins and deep vein thrombosis (DVT), light compression between 14 and 17 mmHg at the ankle is recommended. A moderate compressionof 18 to 24 mmHg is normally used for post-burns hypertrophic scarring treatment. Evidence suggests that a sub-bandage pressure of 35-40 mmHg at the ankle, gradually reducing to 17.5-20 mmHg just below the knee is required to overcome venous hypertension, or for the treatment and management of most venous leg ulcers. Table 1 shows the UK classification of compression bandages and the level of pressure generated at the ankle by each bandage type. The European classification of compression hosiery with the range of pressures exerted around the ankle is shown in Table 2 (6). Table 1. UK Classification of Compression Bandages (6) Class 1
2 3a 3b 3c 3d
Bandage type Bandage h c t i o n Lightweight conforming Used to hold dressings in place Light support Used to prevent the formation of oedema and support mild sprains and strains Light compression Exert a pressure range of 14-17 mmHg at the ankle Moderate compression Exert a pressure range of 18-24 mmHg at the ankle High compression Exert a pressure range of 25-35 mmHg at the ankle Extra-high compression Exert a pressure of up to 60 mmHg at the ankle
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Table 2. European Classificationof compressionhosiery (6) Class
support __
1 2 3 4
Light Medium Strong
Heavy
British standard French standard German standard BS6612:1985 ASQUAL:1999 RAL-GZ387:2000 14-17 mmHg 10-15 mmHg 18-21 mmHg 18-24 mmHg 15-20 mmHg 23-32 mmHg 25-35 mmHg 20-36 mmHg 34-46 mmHg Not reported >36 mmHg >49 mmHg
For the compression therapy, there are a wide range of flat bandages and tubular bandages and hosiery available, each type suitable for their specific applications. Longstretch bandages, which can be woven, knitted or nonwoven contain large proportions of elastomeric yarns, such as Lycra and are widely used in the UK as a two-layer system with a suitable orthopaedic padding bandage. Short-stretch bandages, extensively used in Europe, Australia and recently introduced in the UK, are in-elastic bandages in that no elastomeric yarns are used in their woven structure. Short-stretchbandages normally lock out at up to 70% extension and are applied at the maximum stretch with 50% overlap, on the other hand, long-stretch bandages can have over 140% extension. The latter are normally applied at 50% extension, with rectangles for different ankle sizes indicated on the bandage, which become squares when stretched at the correct extension during application. The four-layer compression system is still popular in the UK, although it is too cumbersome, complex and uncomfortable from the patients’ perspective. Rigid compression delivery systems such as Unna’s Boot, an inextensive bandage impregnated with zinc paste, are more popular in the USA.
RECENT ADVANCES IN COMPRESSION THERAPY Research has shown that long-stretch bandage systems (class 3c) produce a relatively constant sub-bandage pressure. This will increase a little on movement, and drop slightly when still. European short-stretch bandages provide a low resting pressure and high working pressure as a result of their minimal extensibility. On application, the bandage provides a rigid support surrounding the leg which does not give on calf movement, resulting in a high sub-bandage pressure. When the patient is immobile (calf muscle inactive) the sub-bandage pressure is lower (4). In a three-year research and development programme carried out at the University of Bolton, with financial support and collaboration &om the Department of Trade and Industry (DTI), UK and five medical textile companies, a number of innovative instruments and products were developed and characterised. The major outcomes of this project are summarised here: An electric pressure transference apparatus: to determine the amount of pressure absorbed and dissipated within the bandage structure and the actual pressure felt immediately below the bandage i.e. the patient’s leg, was designed, evaluated and utilised in the project (7). An electronic pressure profile instrument (MannequinLeg): to investigate the graduated pressure mapping or profile of two-layer, three-layer and four-layer systems, as well as of the novel compression systems developed during the research programme (7).
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c) Novel padding bandages: these were developed and I l l y characterised to; a) enhance the absorption and rate of absorption of artificial blood solution; b) to impart superior pressure distribution around the leg and hence treat the leg like a cone; and c) to provide extra cushion and comfort to the patients’ leg after bandaging (8). d) Novel vari-stretch compression bandage: a novel spunlaid nonwoven compression bandage was developed which possessed variable compression along the length of the bandage. It was possible to vary the compressional properties of this novel bandage by varying the number of Lycra threads incorporated into a spunlaid fabric on line, so that 50% of the length of the bandage was 3c type and the other 50% of the length was 3a type by controlling the number of Lycra threads introduced in the bandage on line. Figure 1 clearly illustrates the superior contribution of both the novel padding bandage (NPB8) as well as the novel vari-stretch nonwoven compression bandage developed during this research programme. A combination of the novel padding bandage (NPB8) and the novel vari-stretch compression bandage achieved the optimm pressure profile with much reduced pressures at sensors 1 and 2 or at the ankle, when tested on the electronic pressure profile instrument (Mannequin Leg), see b) above (8 and 9).
SINGLE-LAYER COMPRESSION BANDAGES In another Engineering and Physical Sciences Research Council (EPSRC) UK funded research programme at the University of Bolton, a novel single layer bandage system for the treatment of venous leg ulcers has been designed, tested and evaluated, and the results verified through pilot user study involving volunteers of different age groups. A novel three-dimensional weft knitted spacer fabric has been designed and developed by using Finite Element Modelling and Laplace equations for determining sub-bandage pressure. It has been demonstrated in this programme that 3D single layer bandage (used without a padding bandage), meets the ideal criteria stipulated for the compression thempy for the treatment of venous leg ulcers. Figure 2 illustrates that the novel weft knitted spacer bandage produces the desired compression profile fiom the ankle to the knee and the profile is comparable to the commercial two layer system of Surepress plus padding, Setopress plus padding and Tensopress plus padding, when tested on the mannequin leg equipment. The added advantages of using a single layer compression bandage are that a lighter system, that would be much more breathable and hence more comfortable fiom the patient’s perspective, would be achieved. This innovation is currently the subject of a patient application and is also in the process of being commercialisedthrough a UK medical textile company (10).
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Figure 1. Pressure profile of sh@e wd two-layer systems of standard and novel ban-
- -.
I______
-
Figum 2.
Resnm profile of novel 3D and commercial ban-
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on mannequin leg equipment
--
REFERENCES
1 S Ghosh, A Mukhopadhyay and M S i b Progress in Textiles: Science and Technologv, Volume 3, Technical Textiles, IAFL Publications, New Delhi, India, page 280,2008. 2 S Rajendran and S C Anand, Indian J of Fibre and Textile Research, 2006 31 22 1. 3 S Rajendran, A J Rigby and S C Anand, J o f Woundcare, 2007 16(1) 24. 4 S Thomas, 'Science of Compression Bandaging, Compression Therapy: A Complete Guide', J of Woundcare, 1998 7(7) 323, Published by EMAP Healthcare, London, July 1998.
5 S Thomas, World Wide Wouna!~,5" February 1998. 6 S Rajendran, A J Rigby and S C h a n d , J o f Woundcure, 2007 16(3) 108-109.
7 S C Anand and S Rajendran 'Design and characterisation of novel medical devices for venous leg ulcer treatment' int c o d Indian Textile Association, Bhilwara, India, 20" and 21'' December 2008.
8 S Rajendran and S C h a n d , 'Advanced textiles for wound compression', in Advanced textiles for wound care, Ed. S Rajendran, Woodhead Publishing Ltd; Cambridge, UK, 2009, p. 166. 9 S C h a n d , 'Recent advances in medical devices for compression therapy', Lecture to Doctors and Consultants, Royal Bolton Hospital, Bolton, UK 17* June 2009, contact: scal @bolton.ac.uk 10 G Lee, S Rajendran and S C Anand, 'Single-layer compression bandage system for chronic venous leg ulcers', British J o f Nursing, 13" August 2009 S4-Sl8.
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BIOMATERIALS WITH CONTROLLED ELASTICITY FOR POSTOPERATION RECOVERY M. Carmen and E. Alexandra The Research-DevelopmentNational Institute for Textile and Leather, 16 Lucretiu Patrascanu Str., Bucharest, Romania
ABSTRACT Biomaterials with elastomer content are non-invasive, rectangular, flexible, medical devices made of fabrics reinforced with elastic yarns, having longitudinal direction elasticity. Main scope of non-invasive medical devices with elastomer content is constituted by assuring of an external, controllable pressure exerted over body. Biomaterials with elastomer content can be applied under spiral or circular shape on different parts of the body (legs, arms, and thighs), with various anatomies, with the aim of: treating contortions or cricks - biomaterial’s stretching and elongatiodstretch recovery properties provide support for the disjointed limb; treatment and prevention of thromboses, ulcerations and varicosity - product confers a controlled compression (contention) over affected areas. Biomaterials with elastomer content have been designed and manufxtured so as to respond to following requests imposed by clinical use field, respectively: n o d i t a n t contact surface with skin; comfort - lack of coarse material seams and joints; tolerance at human body contact; malleability - adaptability to affected organs typo-dimensional dynamics, morphology and diversity; resistance to chemical and thermal agents; reusability. In case of motion, articular or muscle affections, pressure effect concribUtes to maintaining the functions of affected organs by direct.or indirect action of bandage applied, efficacy degree being correlated with proposed scope. In case of circulatory disorders, pressure exerted by elastic biomaterial cumulates with the tissues specific one, resultant obtained being opposed to venous hydrolstatic pressure, with effect in limiting vascular walls extensibility. Simultaneously with veins caliber decrease, an increase of circulation speed takes place. The paper presents main accomplishments of the multidisciplinary teams of specialists within INCDTP in making such products that should fulfill the requests of biocompatibility and bio-functionality imposed and also stages run for products promotion through EC mark attaining.
INTRODUCTION The world-wide studies have emphasized the fact that the main purpose of the noninvasive medical devices containing elastomers is maintaining an external, controllable pressure to the body. In this respect, according to the definition, the elastic bandage is a non-invasive, rectangular, flexible medical device and it is made of woven fabric reinforced with elastic yams, having elasticity in the length direction. It can be applied under spiral or circular shape on different body parts (legs, arms, thighs), having varied anatomy. The elastic textiles meant for medical devices can be classified depending on the domain of usage, according to the table below. The main characteristics of these types of products are: 0 Woodhead Publishing Limited, 201 0 263
- easy applicationin helix form or as continuous sheets ;
- easy fixing on various body areas by using rapid accessories; - relatively low costs. Domains of usage : - treating of dislocations or of distractions - the dressing properties of stretching and reversion that offers support for the treated limb; - treating and preventing thrombosis, ulcerations and varices - the elastic dressing ensuring a controlled compression (setting) over the affected area. The clasification of the elastic textile materials meant for the medical field Nr. Domainofusage Symbol Functions Crt
1.
Treating of the traumatisms,lesion type Wounds, bums
TTL
Type A
2.
Post-surgical recovery General and recovery surgery
RPO
TypeA+B
3.
Treating and recovery of locomotor system TRL Lumbar ischialgia and sciatica (the acute or the recovery phase) disk prolapse post-surgical evolutive setting) Lumbar pains of traumatic or rheumatic origin (muscular or ligament ruptures and laxities, rib fissures, arthritis, arthrosis etc.) Treating and recovery of the circulatory system TAC Anti-thrombosis, anti-varicose,anti-embolism
4.
Type B
TypeB
Type A - dressing fixing; Type B - setting. Also, the dressings accomplished as part of the research project respond to the specific technico-functionalrequirements, that is: Characteristic The usage domain symbol RPO Tlu TAC Elasticity Very good Very good Very good Compactness Very small Very big Very big Handle Very soft soft soft Compression capacity Very good very good very good Permeability to - liquids Very good good good - vapors good good good - perspiration good good good -air very good very good very good where: RPO - post-surgical recovery; TRL - treating and recovering of the locomotor, muscular and bone system ; TAC - ckular system treating and recovering. The setting pressure can be defined as the force exerted over the body by the elastic medical device when this is used under n o d recovery clinical conditions. In the case 264 0 Woodhead Publishing Limited, 201 0
of certain motor affections, joint or muscle, the pressure effect contributes to maintaining the effected organ functions by the direct or indirect action of the applied dressing, the efficiency degree being correlated to the envisaged purpose. In the case of circulatory disorders, the pressure exerted by the plastic material is cummulated with the one that is specific to the tissues, the obtained result being of a reverse sense to the venous hidrostatic pressure, having effect in limiting the vascular wall distensibility. At the same time with the vain calibre decreasing there takes place a circulation speed increasing. The elastic dressing comes back to its initial characteristics after repeated launderings. The designed and accomplished elastic dressings respond to the following requirements imposed by the clinical utilisation field: - their surface of contact with the skin should be non-irritating; - they should not show coarse stitches or seams that can affect their function or produce discomfort; - they should be well tolerated by the human body; - they should fit to the body shape, being adaptable to its movements; - they should be resistent to various chemical and thermal agents; - they should get adapted to the requirements imposed by the morphological characteristics of the various organs and to the tipodimensional diversity of these; - they should be reusable. The yarns used in accomplishing the woven structure versions were tested in the INCDTP in accredited laboratories according to SR EN ISO/CEI 17025:2001, in order to establish the main physico-mechaniccharacteristics. The physico-mechanic characteristics of the yams used in structure are given in Table 1, the data of woven structure designing are given in Table 2, and the programming charts are given in Figs. 1 and 2. For ensuring the physico-chemical and biologic characteristics (sensitizing potential, irritability, cytotoxicity), the products were subject to a complex finishing process.
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Table -1 Yarn Characteristics Characteristic PES yam
Cotton yam
Elastomer yam
358x1 32 1079,7 29,2 126 390 (323)
24,1/4
Nr 32/36
867,2 12,l 250
958,3 785
Length density dtex, Nm Filament number Breakage load, gf Break elongation, % Twist, t/m Tenacity, gfldtex (gflden) Break length, lan
20,8
Table -2 Woven Structure Specifications Version no. Fibrous composition Warp Weft
v1
v2
100%PES + 100%elastomer yam 100% PES
100%cotton + 100%elastomer yarn 100%cotton
300 den Nr 32/36 300 den
Nm 2414 Nr 32/36 300 den
120/2,2,2,1 I:3+4+2 4 120 (60x2) 105 95
100/2,2,1 1:3+4+2 4 90 (45x2) 115 100
Yarn count warp
Weft Reed no.1yarn no. Harness number
Dbry d c m Reed length., mm
The technological parametres that are afferent to each technological stage of finishing elastomerscontaining biomaterialsmeant for orthopedy are given below: Technological stage name washingdegreasing Rinsing Neutralizing
Used materials IDROSOLVAN NaOH
Warm water Cold water Acetic acid 60%
Sterilizing
Hydrogen peroxide
Alternative rinsings
Warm water Cold water
M.U.
Parameter name
Value
Temperature Time Quantity
OC H
60 1
rsll
20 4
Quantity Time Quantity Time Temperature
ml/l
22 2 15 20 24 4
Time
H
H 811 H "C
2
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t
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Technological stage name
Apparatus/ Device
Washingdegreasing
Automatic washing machine
Rinsing
Automatic washing machine
Neutralizing Sterilizing
Automatic washing machine Stainless tank
Alternative rinsings Drying
Automatic washing machine Drying stove
Remarks
- for removing anti-static treatment products, oil traces, metallic filing left on the fabric following the technological process. - for removing the washing-degreasing solution - for ensuring a neutral PH
- for ensuring the level imposed to the physical-chemical characteristics - for removing the sterilizing solution
The products' packing is done in special multistratifiedpacking materials. The elastic bandages have dimensions of 140U140 x 95*10 mm and of 250W250 x 10U10 mm. The testing under clinical conditions was effected in cases of partial immobilization of some distractions at the level of tibio-tarsal and radiocarpal joint appeared after certain traumatisms. Preliminary Conclusions: - the products have been well tolerated, no adverse reaction provoked by the woven textile backing being noticed; - there was ensured a satisfactory imobilizing at the same time with the possibility of certain limited movements in the joint; - the product using contributes to reducing the pain provoked by the movement. The application manner is very simple and the comfort degree is satisfactory. This type of imobilizing by using elastic bandages is preferable in the minor and moderate forms of distractions, subdislocationsand even recurrent dislocations . Also, the specialist physicians consider as useful the using of such bandages for the varicose illness of the legs by "putty'' type wraping that prevents hemostasia in the superficial venous system. It can be used as palliative as part of the complex treatment for the varicose illness. As a conclusion, this bandage type is considered extremely useful and efficient in the above mentioned pathological situations. The "in-vitro" testing was carried out in collaboration with the National Institute of Chemical-Pharmaceutical Research Development - Bucharest and it aimed at the following estimations: TESTING CYTOTOXICITYAND SENSITIZING POTENTIAL The cytotoxicity testing is regulated by ISO-10993-5: " Cytotoxicity Tests -'In vitro' Methods". Following the observation period, the cells are collected h m the substrate and the viability index is determined.
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So that the product should not induce morphological modifications of the cells in the culture, the treated culture aspect must be practically identical to that of the non-treated blank cultures. The admisibility conditions are given in Table 3. Table -3 Admisibility conditions crt. No. Sample Viability index 97% 1 Non-treated blank 2 Elastic dressing 95% The viability index indicates a very good viability for the cells treated with the tested material extract, close to the blank culture values, non-treated The sensitizing reactions usually appear as a result of the repeated or prolonged contact with a chemical substance that interacts with the body immunitary system. The sensitizing reactions provoked by the products applied on the tegument are marked erythema and oedema.
TESTING METHOD The testing was done on Wistar rats weighing 150-180 g. For experimentation purposes, there have been chosen healthy animals that were kept one week before the experiment for getting acustomed to the vivarium conditions, on standardized food and ad libitum water.Before the experiment, the animals have been epilated on their dorsal area. The repeated dressing test, or Buehler, implies the repeated exposure of the animals epilated dorsal area to the tested product. The testing was done on lots of 6 and the results were compared to a blank lot of which epilated dorsal area was covered with a simple gauze dressingThe product has been daily applied, for 14 days. After two weeks of rest, the animals were covered with a topical dressing that contained the tested product. The areas on which the tested product containing dressings were applied have been examined for detecting the presence of reactions (erythemdoedem) that should not be found with the blank animals (non-treated).
RESULTS: SENSITIZINGAND IRRITATION POTENTIAL The animals of the two lots (treated and non-treated) showed, under microscope, a similar aspect without noticing oedema or erythema type reactions . One can say that the product has no sensitizingpotential The testing was done on white rabbits, of the Chinchilarace, male, weighing 2000-2400 g, distributed in lots of 6 animals each. These were bilaterally epilated, on a portion of 2 cm diameter each, in the hind 31d part of the dorsal area. The right side epilated portion was the testing area for the product and the counterlateralarea was the blank area. On the teasted area there was applied a portion of 1 cm2 of the tested biomaterial , it was covered with a sterile dressing and then an occlusive dressing was made, while on the blank area there was applied a sterile compress, also under occlusive dressing .The tegument covered by dressings was observed after 24 and 48 hours, respectively. The evaluation of the observed effects is done after the following conventional notation: 270 0 Woodhead Publishing Limited, 201 0
0 = well tolerated; 0.5 = slight imtation (discrete skin pigmentation or ischemia, dehydration, simple tegument or in course of epithelization); 1 = present irritation (erythema, oedem, dehydration, thin crust, slight desquamation,furfuraceous); 2 = strong irritation (erythema, oedem, thick crust, scars); 3 = very strong irritation (thick crust, eschars, necroses, scars); The evaluation depending on the irritation degree during the period of noticing the phenomena is the following: well tolerated product: irritability index 0-1, with amending in 1-5 days; - mediocre tolerance :irritability index 1-2, with amending in 6-8 days; -non-toleratedproduct: irritability index 2-3, with amending in 8-12 days. After 24 horn the treated tegument had an aspect slightly higher than in the blank area, the irritability index being 0.5. The noticed phenomena were amended after 48-72 hours, which allows the classification of the product into the category of the well tolerated ones The slight reaction can be due to the material rigidity and not to its irritating potential.
-
CONCLUSIONS The accomplished elastic dressings represent an absolute novelty internationally, their origmality character being conferred by the product conception as a whole, in accordance with the specific destination exigencies, for which they are detining: raw material type, structure type, geometrical and technical characteristic, the values of the assembling and adjusting parametres for the finishing stages, so that there will be ensured the level imposed by the international standards for the physico-chemical, biological and microbiological characteristics. The products satisfy the requirements on the external market by: - technical, biofimctional and biomedical characteristicscorrespondingto the clinical utilisation fields and according to the limits stipulated by the international nodves; - the increasing of product quality, efliciency, safety and durability in functioning by ensuring the performance parameter level stipulated by the standards in force; - the turning into good account of the research potential from the field of textiles having medical destination; - the creating of the premises concerning the designing and accomplishing of new products for the medical field. The biocompatibility tests brought forth the lack of a sensitizing, irritating and cytotoxic potential of the tested dressing (bandage) .
REFERENCES 1 S Adanur, Handbook of Industrial Textiles, USA, Johnston Industries Group, Technomic Publishing Co. Inc., 1995.
2 A Glick, Bioresorbable surgical device for treating nerve defects, US Patent Office, Pat No 4 870 966. 3 M Grindea, A Grigoriu Tehnologie chimica rextilu, Bucuresti, Editura Tehnica, 1981.
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A STUDY OF THE PRESSURE PROFILE OF COMPRESSION BANDAGES AND COMPRESSION GARMENTS FOR TREATMENT OF VENOUS LEG ULCERS M.Sikka, S. Ghosh and A. Mukhopadhyay Department of Textile Technology,National Institute of Technology, J a l a n m India ABSTRACT A study has been conducted on the commercially available compression bandagesand tailor made compression garments as regards their performance with time. Pressure mapping of these bandages is done using a fabricated pressure measuring device on a mannequin leg to see the relationship between pressure, creep and fiction to predict the performance of the compression material. The results show that the creep behavior has a significant effect on the pressure profile generated by the bandagesand garments during application. The regression analysis shows that the friction inhibits the creep in a multilayer bandage system. In case of compression garments, the washing definitely improves the pressure generated but not to the extent of the pressure of a virgin garmed. Comparing the two compression materials i.e. bandage and garment, it is found that the presence of higher percentage of elastomeric material and a highly close construction in case of garment provides good holding capacity and a more homogeneous pressure distribution. Also the garments give a lower value of delayed extension and permanent set and thus are better than bandages for repeated usage and better holding power. Moreover being tailor made another important benefit to compression garment lies in h e integrated medically corrected “compression gradient”. But high cost and unsuitability for use at night or during rest due to higher resting pressure suggests that a well rounded approach to complete therapy for the treatment of any ailment lies in the rotation between bandages and garments. INTRODUCTION Leg ulcers are a chronic condition Depending upon the location and severity of the problem, this may affect large parts of the leg or smallerlocalized areas of tissue. Blockage or damage to the venous system causes disruption to normal blood flow, which may manifest itself in a number of different ways according to the site and extent of the damagd. If the valves in the superficial system are affected, venous return will be impaired and blood may accumulate in the veins causing them to become distended, leading to the formation of varicosities (varicose veins). If the h c t i o n of the perforator valves is impaired, the action of the calf muscle pump will tend to cause blood to flow in the reverse direction into the superficial system increasing the possibility of damage to the superficial vessels following a deep vein thrombosis that result in complete or partial obstruction of a deep vein. Ifthis occurs, there will be a large rise in the pressure inthe superficial system, which may force proteins and red cells out of the capillaries and into the surrounding tissue. Here, the red cells break down releasing a red pigment which causes staining of the skinan early indicator of possible ulcer formation It is commonly found that up to 1% of adults will suffer from leg ulceration at some time2. Prevention and treatment of venous ulcers is aimed at reducing the pressure either by
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removing / repairing the veins, or by applying compression bandages / stockings to reduce the pressure in the veins. The vast majority of venous ulcers are healed using compression bandages. Once healed they often r e c u ~Even the recurrence rates are high, with two third of the patients experiencing one or more recurrend and so it is customary to continue applying compression in the form of bandages, tights,stockings or socks in order to prevent recurrence. Graduated compression hosiery is accepted as an integral part for both as an active treatment for healing ulcers and having an essential role in the prevention of venous ulcer reo~currence~~. The compression bandage form a major category among different bandage types that are used for the application of clinically effective levels of pressure, applied to modify or assist the physiological process of blood flod. These bandages should have good holding capacity during use and also be suitable for repeated use. These properties are affected by the creep behaviour, the fictional behaviour and constructional parameters of the bandage material. For patients with venous disease, the application of graduated external compression can help to minimize or reverse the skin and vascular changes described previously, by forcing fluid from the interstitial spaces back into the vascular and lymphatic compartments. In the present work an attempt has been made to study the pressure profile generated by the compression bandages and garments using fabricated prototype pressure measuring device (mannequin leg). The effect of creep and fabric to fabric friction on the pressure profile of the compressionbandages is noted to assess their contribution for repeated usage. MATERIALS
Eight different samples of compression bandages commercially available in India were analyzed in the laboratory for their constructional parameters as given in Table 1. It was observed that the samples 1-6 had rubber being inlaid as an elastomeric component and sample 8 had fine lycra yam being knitted into the structure. The compression bandage samples (1 to 6) have warp component as polyester but vary in the mislapping threads which is either polyester or plied cotton yam or a combination of polyester and cotton in different ratios.
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Table 1. Structural characteristics of compression material Yam linear
Thread density (per cm)
density (tex)
Sample TypeofMaterial
Warp
Wefi
No.
3
5
Wales Courses LOOPS /ends /picks
warplolittad
66
63
3
9
warpknitted
66
46
3
8
warpknitted
66
27
3
8
warpknitted
66
119
3
6
warp knitted
66
66 30
3
7
warpknitted
66
66 5s
3
7
CrepeLenohbric
54 29
66
24
27
30
30
Weft knitted
35
Garment
METHOD
Tests regarding creep measurement, friction measurement and the pressure mappingwere done in a standard testing environment using standard test methods with the fabricated devices. A prototype electronic device (a mannequin leg) was used to investigate the pressure mapping of the bandage and the garment systems. Three resistance foil strain gauges were fitted on the mannequin leg. For creep testing a dead weight system of loading was used on the fabric and the fabric to fabric Ection was calculated h m the trace generated by the universal testing machine (Zwick).
RESULTS AND DISCUSSION
AU the structures except crepe bandage have elastomeric material in different ratios Further, the placement of the elastomeric yam in the fabric also varies in tach type of structure.The effect of creep and the fabric to fabric fiiction is clearly observed in pressure profile of the bandages.
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High compression bandages Creep behavim It is observed that as the load on the bandage material is varied the extension of the material increases steadily. However, in case of recovery, the total recovery may or may not be higher for the samples stretched at higher load because all the samples follow d ~ e r e n t patterns of delayed recovery and permanent set due to their inherent characteristics. Different sample behave differently with the time. The holding capacity of a bandage fabric can be. judged by primary creep performance of the fabric although the creep effect is partially inhibited by fi-ictional effect in a multilayer system. In case of reuse of bandage fabrics, the fabric possessing lower permanent set should be preferred.It has been seen that the bandage fabric of higher weight does not necessarily perform the best as far as the holding power of the fabric on the affected body part is concerned over a longer period of time7. It may be added that the cost factor is also high for the fabric of higher weight. Pressure profile The pressure profile of the compression and crepe bandages against time at three diferent locations on the limb are given in Figure 1622. It is observed that the change in pressure at the calf and knee position is not so significant due to more or less flat circular profile at these points. Further the pressure falls for the repeated weaxing of the bandage due to the permanent set generated in them in both the cases. It is also observed thatthe pressure of the bandages at three critical points on the surface of the leg as calculated using Laplace Equations and the actual pressure show some difference in their values especially at the knee position. As expected the pressure reduces with time because of the creep which in turn is counteracted by frictional behavim of the bandage fabric. A slight fall in pressure is observed at the calf ard knee position but at the ankle substantial change is observed The typical geometry at the ankle position may be responsible for layer slippage. But this observation is not true for crepe bandage
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.
40
+Pressure
35
- - - .PrcsSurC -1st
3
*pressure
1:
at ankle wear
at calf
--n--F?essureafterlstwear -0-
Pressure at knee
- - 0 - .Pressure afterlst wear
20 15
Fig 1 Pressure profile of compressionbandage 1 (See Table 1)
Time series (min) Fig 2 Pressure profile of crepe bandage
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Compression garment Pressureprofile The pressure profile of the compression garment is shown in figure 3 at three different positions. It indicates an initial increase and then decrease in pressure at ankle and slight decrease in pressure at calf and knee. Also the drop in pressure is more at the ankle as compared to calf and knee which may be due to higher permanent set values at the ankle position that may be attributed to the geometry of the ankle. Furthermore, there is a marginal drop in pressure at the calf and knee positionsalso. It is also observed from Figure 3 that the change in pressure over time is not so sigmficant in case of the garment as compared to the bandages due to the low value of delayed extension.
::L: 17
16
I
1
10 Tm(rr6n)100
loo0
CONCLUSIONS
Compressionbandage used for the similar application exhibit a lot of variability regarding the material used, constructional parameters of the yam and fabric set and structures. The value of pressure shows some deviation Erom the Laplace equation at the knee which needs further investigation and research At the other points the values are nearly same as calculated by Laplace equation. The decay parameter of the pressure in case of bandages is largely governed by the creep and fictional force. As regards holding capacity of the bandages with time, the fabric of higher weight may not perform the best. Furthermore, in the existing bandage material, the bandage that is most suitable for repeated use may not be very suitable to offer good holding during use and vice-versa. On the other hand the
’.
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compression garments give a lower value of delayed extension and permanent set maintaining the pressure at a level over a longer time,
REFERENCES 1 S Thomas, ‘Compression bandaging in the treatment of venous leg ulcers’, Worldwide Wounds, 1997.
2 E A Nelson, B Seyer, N A Cullum, ‘Compression for preventing recurrence of venous ulcers’, 2000, The Cochrane Database of systematic reviews, Issue 4, Art. No. CD 002303.DOl: 10.1OOY14651858.CD002303. 3 S C Anand and S Rajendran, ‘Design and characterization of novel medical devices for venous leg treatment’, int confEmerging @en& in PoZymers and Textile, Indian Institute of Technology, New Delhi, India, Ed. M Jassal & A Aggarwal, 155-167,2005. 4 R Judith and S Casley, ‘Compression bandages in the treatment of Lymphoedema’ www.worldwidewouuds.com (LAA, University of Adelaide) 2002. 5 R hidth and S Casley, ‘Compression garments for the treatment of Lymphoedema’, www.worldwidewounds.com 2002.
6 S Johnson, ‘Compression hosiery in the prevention and treatment of venous leg ulcer’, J of Tissue Viability, 2002 12(2) 67-14. 7 A Mukhopadhyay and S Ghosh, ‘Creep performance of short stretch bandages’, Indian J of Fibre and Textile Research, 2005 30 33 1-334. 8 S Thomas, ‘The use of the laplace equation in the calculation of sub bandage pressure’ www.worldwidewounds.com,2003. 9 L Macintyre, M Baird, P Weedall, ‘The study of pressure delivery for hypertrophic scar treatment’, Medical Textiles and Biomaterialsfor Healthcme, S C Anand, J F Kennedy, M Mirafiab, S Rajendran, eds Woodhead Publishing Limited, Cambridge, UK,2003, 224221,2003.
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DEVELOPMENT OF TElREEDIMENSIONALSTRUCTURES FOR SINGLELAYER COMPRESSION THERAPY S. Rajendran and S.C. h a n d Institute for Materials Research and Innovation,University of Bolton, Bolton BL3 5AF3,UK ABSTRhCT Venous leg ulceration is a common problem throughout the western world. The chronic nature of venous ulcers creates considerable demands upon all healthcare authorities in terms of treatment costs and nursing resources. Compression bandaging is considered as the “gold standard” for managing venous leg ulcers and treating the underlying venous insufficiency. The main function of a compression bandage is to exert external pressure onto the limb. The ability to generate and to maintain this sub-bandage pressure is determined by the bandage structure, the elastomeric properties of the yams, as well as the finishing treatments applied to the fabric. Non-woven materials are currently used in combination with compression bandages in an attempt to evenly distribute pressure and provide protection over bony prominences of the leg (tibia). However, these multilayered bandage systems are uncomfortable to wear due to their bulkiness and undesirable thermo-physiologicalcharacteristics.They are also difficult to apply and are associated with relatively high costs due to the requirement for specific bandage types for each layer. The requirement for a single-layer compression bandage that incorporates the performance characteristics of multi-layered comprasion bandage systems is of paramount importance. Three-dimensional knitted spacer fabrics are becoming increasingly important for developing novel medical textile products. In comparison to traditional woven or knitted fabrics, the range of physical and themo-physiological properties which can be achieved is considerably wider. These novel structures consist of two independent faces with interconnecting threadsjoining them. They can be exceptionally soft, incorporate large volumes of air, and provide good resilience to compression, temperature control, and moisture management. The layer of air that lies between the two independent textile faces creates a comforting, climate-controlling effect which prevents sweating and overheating of the skin. Spacer fabrics also provide an excellent cushioning effect which means that there is no need to use multiple layers of padding and compression bandages. When elasticated yarns are incorporated into the spacer fabric structure it is also possible to produce similar pressure-generating characteristics to those of traditional compression bandages. The focus of this paper is to discuss the design criteria and imporkant functional properties of three-dimensional single-layer compression systems. A range of both weft and warp knitted spacer-fabrics were tested in order to determine their basic functional properties. Mechanical testing was also undertaken in order to assess the elastic and elongation properties of these spacer-fabrics. Load elongation hysteresis is important since it not only relates to the materials ability to generate external pressure, but also how this pressure maybe affected h m any changes in tension, extension, and elastic properties. The tension, and hence external pressure, generated within traditional compression bandages normally decays slowly over an extended period of time after application onto the limb. The tension decay test simulates bandage application and 0 Woodhead Publishing Limited, 2010 279
highlights a materials ability to sustain tension throughout a pre-determined time period (15 hours). Thermo-physiological and climate-controlling properties of the spacer-fabrics will also be discussed in this paper. These tests directly relate to the functional comfort characteristics of the spacer-fabric structures which include thermal resistance, thermal absorpitivity, water vapour permeability, and evaporative heat loss. In all of the tests undertaken, comparisons are made to results obtained for traditional compression bandages and padding bandage materials.
INTRODUCTION The market potential for healthcare and medical textile devices is considerable. In the EU alone, sales of medical textiles are worth US$ 7 billion, and already account for 10% of the market of technical textiles. The EU sector consumes 100,000 tomes of fibre per annum and is growing in volume by 3% - 4% a year. The global medical device market was valued at over US$lOO billion, of which U S 4 3 billion was generated from the US market. Western Europe is the second largest market and a c ~ u n t for s nearly 25% of the global medical device industry. The UK has one of the largest medical device markets in the world. The market is dominated by the National Health Service (NHS)accounting for approximately 80% of healthcare expenditure, even though there are fewer private sectors. It is forecasted that the share of hygiene and medical textiles would be 12% of the global technical textiles market and would account for US$4.1 billion. The healthcare and medical devices market is being driven by: 0 population growth in developing countries; 0 the ageing of the population in developed countries; 0 rising standards of living and higher expectationsof quality of life, 0 changing attitudes to health, and 0 the emergence of innovations and the availability of increasingly high technology. Innovations mainly come fiom large companies which have their own research and development departments. However, many novel products will continue to be developed by small and medium size companies - albeit largely through collaboration with universities and higher educational institutions. Venous ulceration is a common disease affecting around 1% of adult population in the UK and Australia. The direct and indirect cost of the treatment in Germany is more than 1 billion DM. The estimated annual cost in Sweden is $25 million. In the US, about 2 million working days are lost each year because of leg ulcer problem and the treatment cost is enormous. It is estimated that the direct cost of management and treatment of venous leg ulcers to the National Health Service (NHS) in the UK is in excess of f8OO million. "HE TREATMENT OF VENOUS LEG ULCERS
As stated earlier, venous leg ulceration is a common problem throughout the Western world. Venous leg ulcers are the most fiequently occurring type of chronic wound accounting for over 70% of the lower extremity ulceration and the recurrence rates are as high as 72% in one year'. It should be pointed out that venous leg ulcers are chronic and there is no medication to cure the disease other than the compression therapy. A sustained 280 0 Woodhead Publishing Limited, 2010
graduated compression mainly enhances the flow of blood back to the heart, improves the functioning of valves and calf muscle pumps, reduces oedema and prevents the swelling of veins. Mostly elderly people are prone to develop Deep Vein Thrombosis @VT - popularly known as blood clot), varicose veins and venous leg ulcers. However over 40% of patients suffer prior to age 50 and 13% before the age of 30’. The chronic nature of venous ulcers creates considerable demands upon all healthcare authorities in terms of treatment costs and nursing resources. Compression bandaging is considered as the “gold standard” for managing venous leg ulcers and treating the underlying venous insufficiency. The main function of a compression bandage is to exert external pressure onto the limb. The ability to generate and to maintain this sub-bandage pressure is determined by the bandage structure, the elastomeric properties of yarns and the finishing treatments applied to the fabric. Nonwoven material is currently used in combination with multilayer bandages in an attempt to evenly distribute pressure and provide protection over bony prominences of the leg (tibia). However, these multilayered bandage systems are uncomfortableto wear due to their bulkiness and undesirable thermophysiological characteristics. The ideal requirements of pressure transference and distribution are of p a t concern. Multilayer bandages are also difficult to apply on the limb and are associated with relatively high costs due to the requirement for specific bandage types for each layer. In these circumstances, the requirement of a single-layer compression bandage regime that incorporates the ideal performance characteristics of multilayered compression bandage systems is of paramount importance. A single layer system would be simpler to apply, relatively more comfortable to patient and above all will be relatively cheaper than two to four layer systems currently available on the market.
COMPRESSION SYSTEMS Compression can be exerted to the leg either by a single-layer bandage or multilayer bandages. In the UK four-layer bandaging system is widely used whilst in Europe and Australia the non-elastic two-layer short stretch bandage regime is the standard treatment. A typical four-layer compression bandage system comprises of padding bandage, crepe bandage, high compression bandage and cohesive bandage. Both the two-layer and four-layer systems require padding bandage (wadding or orthopaedic wool) that is applied next to the skin and underneath the short stretch or long stretch compression bandages. A plaster type non-elastic bandage, Unna’s boot is favoured in the USA. However, compression would be achieved by three-layer dressing that consists of Unna’s boot, continuous gauze dressing followed by an outer layer of elastic wrap. It should be stressed that Unna’s boot, being rigid, is uncomfortable to wear and medical professionals are unable to monitor the ulcers afler the boot is applied. A variety of padding bandages are used beneath the compression bandage as a padding layer in order to evenly distribute the pressure and give protection to bony prominences. They absorb high pressures created at the tibia and fibula regions. It will be noticed that the structure of a padding bandage is regarded as an important factor in producing a uniform pressure distribution. Research has shown that the majority of commercially available bandages do not provide the desired uniform pressure distrib~~tion~.~.
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PROBLEMS WITH CURRENT BANDAGES
During the past few years there have been increasing concems relating to the performance of bandages especially pressure distribution properties for the treatment of venous leg ulcers. This is because the compression therapy is a complex system and requires two or multilayer bandages, and the performance properties of each layer differs h m other layers. The widely accepted sustained graduated compression mainly depends on the d o r m pressure distribution of different layers of bandages in which textile fibres and bandage structure play a major role. The padding bandages commercially available are nonwovens that are mainly used to distribute the pressure, exerted by the short stretch or long stretch compression bandages, evenly around the leg otherwise higher pressure at any one point not only damages the venous system but also promotes arterial disease. Therefore there is a need to distribute the pressure equally and uniformly at all points of the lower limb and this can be achieved by applying an effective padding layer around the leg beneath the compression bandage. In addition, the padding bandages should have the capability to absorb high pressure created at the tibia and fibula regions. Wadding also helps to protect the vulnerable areas of the leg h m generating extremely high pressure levels as compared to those required along the rest of the leg. The research carried out at the University of Bolton involving 10 most commonly used commercial padding bandages produced by major medical companies showed that there are significant variations in properties of commercial padding bandages*’, more importantly the commercial bandages do not distribute the pressure evenly at the ankle as well as the calfregion. The integrity of the nonwoven bandages is also of great concern. When pressure is applied using compression bandages, the structure of the nonwoven bandages may collapse and the bandage would not impart cushioning effect to the limb. The comfort and cushioning effect are considered to be essential properties for padding bandages because they may stay on the limb for several days. In the UK, multilayer compression systems are recommended for the treatment of venous leg ulcers4. ~lthoughmultilayer compression bandages are more effective than single-layer bandage in healing venous leg ulcers’, it is generally agreed by the clinicians that multilayer bandages are too bulky for patients and the cost involved is high. A wide range of compression bandages is available for the treatment of leg ulcers but each of them having Merent structure and properties and this influences the variation in performance properties of bandages. In addition, long stretch compression bandages tend to expand when the calf muscle pump is exercised, and the beneficial effect of the calf muscle pump is dissipated. It is a well established practice that elastic compression bandages that have the extension of up to 200% are applied at 50% extension and at 50% overlap to achieve the desired pressure on the limb. It has always been a problem for nurses to exactly stretch the bandages at 50% and apply without losing the stretch from ankle to calf, although there are indicators for the desired stretch (rectangles become squares) in the bandages. The elastic compression bandages are classified into four groups (3a, 3b, 3c and 3d) according to their ability to produce predetermined levels of compression and this has always been a problem to select the right compression bandage for the treatment. The inelastic short stretch bandage (Type 2) system, which has started to appear in the UK market, has the advantage of applying at full stretch (up to 90% extension) around the limb. The short stretch bandages do not expand when the calf muscle pump is exercised and the force of the muscle is directed back into the leg which promotes venous return. The limitations of short stretch bandages are that a small increase in the volume of the leg will result in a large increase 282 0 Woodhead Publishing Limited, 2010
in compression and this means the bandage provides high compression in the upright position and little or no compression in the recumbent position when it is not required. During walking and other exercises the subbandage pressure rises steeply and while at rest the pressure comparatively drops. Therefore patients must be mobile to achieve effective compression and exercise is a vital part of this form of compression. Moreover the compression is not in tact with skin when reduction in limb swelling because the short stretch bandage is inelastic, and it has already been stretched to its full extent.
3D COMPRESSION BANDAGES Three-dimensional spacer fabrics are becoming increasingly important for developing novel medical textile products. In comparison to traditional woven or knitted fabrics, the range of physical and thermophysiological properties which can be achieved is considerably wider. These novel structures consist of two independent faces with interconnecting threadsjoining them. They can be exceptionally soft, incorporate large volumes of air, and provide good resilience to cornpression, temperature control, and moisture management. The layer of air that lies between the two independent textile faces creates a comforting, climate-controlling effect which prevents sweating and overheating of the skin. Spacer fabrics also provide an excellent cushioning effect which means that there is no need to use multiple layers of padding and compression bandages. When elasticated yarns are incorporated into the spacer fabric structure it is also possible to produce similar pressure-generating characteristics to those of traditional compression bandages. MATERIALS AND METHODS
Four spacer fabrics identified as Black (l), White (2), White (3) and Blue (4) were used to study the pressure transference at various pressure ranges. Four padding bandages (PBla to PB4a) recently available at Drug Tariff were also used for comparison. It should be mentioned that the pressure distribution of 10 commercial padding bandages were earlier studied and reported el~ewhere’.~.
Pressure mapping apparatus The electronic pressure transference apparatus (Figure 1) developed at The University of Bolton was used. The apparatus consists of a wooden platform for presentation of test specimens, a strain gauge device and an electronic circuit board. A pressure pin (9mm diameter) is attached on to the load beam of the strain gauge and a corresponding hole drilled through the wooden platform. The height of the pressure pin is adjusted so that it protrudes through the hole of the platform by lmm. The specimen is placed onto the wooden platform over the pressure pin and a series of known metal block weights are placed onto its surface. The strain gauge device detects the pressure transmitted through the specimen at each known pressure in increments created by the metal blocks. The amount of pressure absorbed and dissipated within the textile structure and the actual pressure felt immediately below the specimen ie the patient’s leg is determined. The transmitted pressure through the thickness of the specimen is the absolute pressure exerted on the patient’s leg.
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Fig 1. Pressure Transference Apparatus A fabric extension device (Figure 2) has also been developed at the University of Bolton which facilitates the extension of spacer fabrics at the required length. The pressure transference of spacer fabrics at various extensions was measured utilising this device.
Fig 2. Pressure Transference Extension Test Rig A prototype electronic mannequin leg developed at the University of Bolton was used to investigate the pressure mapping of bandages. The mannequin leg (Figure 3) simulates a lower limb and has d e h b l e tibia, calf and ankle regions.It has 8 pressuremeasuring sensors of which 2 are positioned at ankle, 3 at calf and 3 at below knee. The sensors are connected with an electronic board display unit via strain gauges.
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I
r'
L
Fig 3. Schematic Diagram of Pressure Profiling Instrument (Mannequin Leg)
RESULTS AND DISCUSSION Effect of bulk density The basic properties of padding bandages and spacer fabrics used in this study are given in Table 1. The bulk density determines the bulkiness of fabrics, higher the bulk density lower is the bulkiness. It is one of the important parameters for treating venous leg ulcers because the padding bandage is applied next to the skin around the leg, and it must be capable of protecting bony prominence and imparting comfort and cushioning effect to the patient. An appropriate bulkiness would be required to protect the bony prominences Table 1. Basic Properties of Padding Bandages (PB) and Spacer Fabrics Sample
Thickness
(mm) PBla Padding PB2a Paddini PB3a Padding PB4a Padding Black (1) Spacer White (2) Spacer White (3) Spacer Blue (4)Spacer
1.2 1.4
1.5 1.4
3.24 2.37 2.41 1.87
Area Density -2
90 93 79 72 475 295 426 279
Bulk Density (gcmJ) 0.07 0.07 0.05 0.05 0.15 0.12 0.18 0.15
in the leg. It is observed in Table 1 that all the commercial padding bandages (PBla PB4a) possess essential bulkiness and the space fabrics registered significant higher bulk densities. It should be stated that spacer fabric is a three-dimensional structure and in 3D spacer fabrics, two separate fabric layers are connected at a distance with an inner spacer yarn or yarns using either warp knitting or weft knitting route (Figure 4). The two layers can be produced from different fibre types such as polyester, polyamide, polypropylene, cotton, viscose, lyocell, wool etc and can have completely different structures6.The three-dimensional nature of spacer fabrics makes them an ideal device for application next to the skin because they have desirable properties that are ideal for the human body'. 3D fabrics are soft have good resilience that provides cushioning
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effect to the body and protects bony prominence, they are breathable and hence the ability to manage both heat and moisture generated by the body6. For venous leg ulcer applications, such attributes together with improved elasticity and recovery promote faster healing.
Fig 4. Illustration of a 3D Spacer Fabric Structure
Effect of pressure transference of commercial bandages Padding bandage is applied beneath the compression bandage. The degree of pressure that is induced into the leg by the compression bandage is of major importance. It has been demonstrated that too high a pressure on the leg not only leads to further complications of venous system but also promotes arterial disease. In contrast, inadequate pressure cannot help to heal the venous ulcers. Even if the compression bandage is applied at the correct tension it is probable that excessive pressure will be generated over the bony prominences of the leg. Therefore there is a need to distribute the pressure equally and uniformly at all points of the lower limb and this can be achieved by applying an effective padding layer around the leg below the compression bandage. The pressure distribution characteristics of commercial bandages are shown in Figure 5 . Obviously, none of the bandages provides uniform pressure distribution. It is vital that an ideal padding bandage should dissipate the pressure between 30 and 4OmmHg, exerted by a high compression bandage (Type 3c), uniformly around the limb. Earlier studies also indicated the poor pressure distribution of commercial bandages2p3.However, a significant improvement in distributing the applied pressure of the novel adding bandages developed at the University of Bolton is reported elsewhere’ In order to ascertain the pressure transference of padding bandages exerted by high compression bandage (Type 3C), a prototype electronic instrument (mannequin leg) was used. The padding bandage was wrapped around the mannequin leg at 50% overlap (two complete layers) without stretching and high compression bandage (SurePress) was wrapped over the padding bandage at 50% overlap by rotating the leg. The compression bandage was stretched at 50% extension by applying 1 kgfload when
s.
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"1
Fig 5. Pressure Transferenceof CommercialPadding bandages wrapping around the leg. It should be stressed that nurses normally apply the bandages at 50% overlap, and at 50% extension for treating the venous leg ulcers. The pressure developed at ankle, calf and below knee positions in the mannequin leg was determined from the display unit and the values were corrected using the regression equations. Prior to the measurement, the pressure sensors in the leg were calibrated to the known pressure range of 0 to 300 mmHg by making use of a sphygmomanometer. The pressure mapping is depicted in Figure 6.
..I
m.m
Fig. 6 Pressure Mapping of Commercial Bandages on Mannequin Leg The interpretation of the results is summarised based on the following two major phenomena.
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1. A sustained graduated compression,higher pressure at the anMe which gradually reduces to calf and upper calf according to Laplace's Law', aids the treatment of venous leg ulcers'. f i e graduated compression mainly enhances the flow of blood back to the heart, improves the functioning of valves and calf muscle pumps, reduces oedema and prevents the swelling of veins". 2. Approximately 30-40 mmHg at the ankle that reduces to 15-20 mmHg (50%) at the calf is generally adequate for healing most types of venous leg ulcers". The ideal pressure just below the knee is around 17 mmHg".
It is obvious from Figure 6 that the bandages do not fulfil the requirements of a sustained graduated compression of an ideal bandage system. The pressure measured by sensor 2 at the ankle is very high although the pressure is graduating down to the knee. It is obvious, however, that all padding bandages exhibited relatively lower compression values than the type 3C high compression bandage when applied on its own without orthopaedicwadding below it. In Figure 6 type 3c Sure Press compression bandage was applied alone and on top of padding bandages PBla to PB4a It is obvious fiom Figure 6 that type 3c Sure Press when applied in conjunction with padding bandages PB2a and PB3a produced the closest results to the theoretical values.
Effed of presswe transferenceof space bandages Pressure transference appamtus and extension test rig were used to study the pressure transference of spacer bandages both at unrestrained and stretch conditions. It will be observed in Figure 7 that the pressure transference of Merent spacer bandages at any one point varies, and it mainly depends on the structure and fibre content of the material. It is interesting to note that spacer bandages distributed the applied pressure much more uniformly around the leg than the four commercial padding bandages PBla to PB4a, see Figure 5. For instance, the White (2) spacer bandage absorbed the applied pressure of 43.9 mmHg and transfer 2 mmHg at one point. In other words the absorbed pressure of 41.9 mmHg is uniformly distributed inside the fabric structure which is one of the essential requirements for venous leg ulcer treatment. On the other hand, the commercial padding bandage (F'B4a) absorbed 43.9 mmHg and transferred 35 mmHg at one point (Figure 5) and this means the bandage distributed only 8.9 d g uniformly inside the structure. The higher out put pressure fiom the bandage at one point is undesirable and may slow down andor block the blood flow in arteries.
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1200
,
-m-Elack
+Blw
(I)
(4)
zml Fig 7. Pressure Transference of Spacer Bandages (Relaxed) Figures 8 to 1 1 represent the pressure transference of spacer bandages at known pressures under extension up to 120%.
o
10
20
x)
a
w
40
m
I
RI
im
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--1w
Fig 8. Effect of Extension on Pressure Transference of Spacer Bandages - Black (1)
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4.m
,
4m.
am.
I
f KI om o
10
20
10
u)
HI
~ J I
m
m
m
Im
-m Fig 9. Effect of Extension on Pressure Transference of Spacer Bandages - White (2) It will be noticed that increase in applied pressure does not influence the pressure transference at any one point and the variation is marginal in all the samples. This affirms that these spacer fabrics can be used as ideal padding bandages, and by controlling the tension it will be possible to generate the required pressure for the treatment of venous leg ulcers.
Fig 10. Effect of Extension on Pressure Transference of Spacer Bandages - White (3)
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Fig 11. Effect of Extension on Pressure Transferenceof Spacer Bandages - Blue (4)) It should also be stated that according to Laplace equation the pressure generated on to the limb by a bandage is directly proportional to the tension of the bandage and the number of layers but inversely proportional to the width of the bandage and the circumference of the limb. Utilising this concept, the research and development programme into the mathematical modelling of spacer fabrics to achieve the required pressure mapping for the treatment of venous leg ulcer is in progress at the University of Bolton. SUMMARY
The effective management of venous leg ulcer involves careful selection of bandages to reverse the venous blood flow back to the heart. The paper has discussed the significant contribution of padding as well as compression bandages in healing the ulcer. The advantages and limitations of the existing two-layer to four-layer bandaging regimens are discussed in this paper. It is obvious that the pressure transference of commercial padding bandages varied and none of the padding bandages investigated satisfied the requirements of an ideal padding bandage. The study also demonstrated the need for developing a single-layer bandaging regimen for the benefit of elderly and cutting the cost of treatment. 3D spacer technology has been investigated and the results affirmed that spacer bandages would be utilised to design and develop a single-layer system that could replace the currently used cumbersome four-layer system. A suitable spacer structure can combine the desirable attributes of both the padding and 2-dimentional compression bandages into one composite 3-dmentiod structure.
ACKNOWLEDGEMENTS The research and development programme is funded by Engineering and Physical Sciences Research Council (EPSRC), UK. The authors are grateful to EPSRC for finding and supporting the research programme.
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REF’ERENCES 1 P N Kimbrell and V Larson-Lohr, ‘Venous Disease’, in P J Sheffield, C E Fife and A P S Smith (Eds), Wound Care Practice, Best Publishing Co,2004,267.
2 S Rajendran and S C Anand, ‘Design and development of novel bandages for compression therapy’, British JNursing, 2003 11 1300-1307. 3 S Rajendran and S C Anand, ‘The contribution of textiles to medical and hdthcare products and developing innovative medical devices’ Indian J Fibre & Text Res, 2006 31 215-229. 4 EHC, ‘Compression Therapy for Venous Leg Ulcers. University of York NHS Centre for Review and Dissemination’, E’ective Healthcure, 1997 3 1-12. 5 N Cullum et al, ‘Compression for venous leg ulcers’, Cochrane Review: The
Cochrane Library,Oxford, 2002,l. 6 S C Anand ‘Spacers- at the technical frontier’, Knit International, 2003 110 38-41.
7 Anon, ‘Spacerfabric focus’, Knit International,2002 109 20-22. 8 C Moffat and P Harper, Leg Ulcers, Churchill Livingstone, Edinburgh, 1997. 9 RCN, Clinical Practice Guidelines. The Management of Patients with Venous Leg Ulcers. RCN Institute,London, 1998. 10 M Collier, Venous Leg Wceration: In Wound Management: Theory and Practice, Edited by M Miller and D Glover, London. Nursing Times Books, 1999. 11 D Simon, ‘Approachesto venous leg ulcer care within the community: compression, pinch skin grafts and simple venous surgery’, Ostomy Wound Management, 19% 42 2 34-40.
12 R Sterner et al, ‘Compression mabnent for the lower extremities particularly with compression stockings’, The Dermatologist, 1980 31 355-365.
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INTERMITTENT PNEUMATIC COMPRESSION AND BANDAGING: THE EFFECTS OF EXTERNAL PRESSURE APPLIED OVER BANDAGING *S. Rithalia, and ** M. Leyden *Schoolof Health Care Professions and **Schoolof Nursing, University of Salford, Salford, UK
ABSTRACT Compression of the legs with elastic bandages or stockings has represented the cornerstone of venous leg ulcers treatment. Recent reports have suggested that external pneumatic compression of the legs in conjunction with the bandagmg enhances the healing of leg ulcers. The effect of intermittent pneumatic compression (IPC) garment pressure applied on top of compression bandaging was investigated on interfke pressure at three different sites, namely the ankle, mid& and below the head of the fibula on the left leg of a healthy adult volunteer. Bandaging using a four-layered technique was carried out sequentially by 12 different nurses trained in bandaging skills. Laser Doppler Flow (LDF) measurements were also carried out at mid-calf site. The external garment pressure applied over bandaging was found to be additive. The LDF reading increased during compression phase of the P C , which may be a significant factor in achieving ulcer healing. Another observation was that only 5 out of 12 nurses generated a required negative gradient from ankle to knee when bandaging the Same leg, the remainder generating null or reverse gradient.
INTRODUCTION It is now known that compression, in the form of bandages, stockings or intermittent pneumatic compression is effective in the treatment of venous leg ulcerslJ. However, there has been much concern in the literature regarding the technique dependency in bandaging, especially pressure distribution properties, and several publications have suggested that bandaging techniques of nurses are generally This is because the compression therapy is a complex system and requires two or multi-layer bandages, and the performance properties of each layer differ from other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages in which textile fibres and bandage structures play a major role7. Compression bandages have been in existence for thousands of years. They have a history stretching back to the time of the ancient Egyptians. However, intermittent pneumatic compression (IPC) pumps have been in existence only for about 50 years*, during which time they have been used therapeutically for a variety of conditions, including the treatment of venous ulcers in numerous studies and in many populations throughout the world9-". Although they may differ slightly in design, material, shape and size, all pumps operate on basically the same principle. The important parameters are the intensity and rate of compression, and the interval between compressions. The procedure involves enclosing the limbs in the garment, which is then periodically inflated with air to a set pressure. Generally, a garment pressure of 40 to 45 mm Hg is used. The intermittent pressure on the chosen limb mimics the pumping action of the muscle, thus improving venous pulsatility and blood flow. Several researchers have also 0 Woodhead Publishing Limited, 201 0 293
suggested that when the veins and muscles are compressed they also release a substance, which dissolves blood c l ~ t s ' ~ * ' ~ . The IPC devices can be divided into two main groups, that is, pumps with single chamber garments and pumps with multi-chamber garments. Another way is to describe the technique as uniform pressure intermittent compression and as sequential or graded compression. In the graded cornpre~sion'~~'~, the treatment cycle starts by filling the distal cell first and continues by inflating the remaining cells in sequence. When the entire garment is filled with air, all the cells automatically deflate and the cycle begins again, thus repeating itself. Therefore, fluid in the limb moves tiom the distal area and progresses proximally. The parameters, such as the inflatioddeflation time and pressure, are either preset by the manufacturers of the pump or manually set by the operator. The objective of the present study was to investigate the effect on interface pressure (IP) of IPC garment pressure applied on top of compression bandaging.
METElODSANDMATERIALS Measurements of sub-bandage pressures were taken at three different sites on the left leg of a healthy adult volunteer: (1) 3 cm above the lateral malleolus (ankle site); (2) maximum diameter around the mid-calf (calf site); and (3) 2 cm below the head of the fibula (knee site). The subject was male, 64 years old, weighing 72 kg and measuring 1.71 in height. The procedure was l l l y explained to him and his Written consent was obtained prior to the commenmmt of taking the measurements. Bandaging using a four-layered technique16was carried out sequentially by 12 different nurses trained in bandaging skills. Interface pressure sensors were t a d to the skin at sites (1) to (3) and conuected to a calibrated Oxford Pressure Monitor (OPM MkII, Talley Group Ltd, Hmts). While the subject was lying supine, measurements were carried out, as follows: (a) bandaging without LPC,(b) bandaging with IPC and (c) LPC alone. The same quiet room, at a regulated temperature between 23' and 26OC, was used to carry out all measurements.
Fig 1. Monitoring set up: (a) computer, (b) box containing air pressure transducers, (c) interface pressure monitor (d) perhion monitor, (e) mouse, (f) keyboard, (g) printer, (3) computer screen and (i) IPC pump.
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A laser Doppler probe (PeriFlux System 5000, Perimed Ltd, Sweden) was attached at site (2) next to the interface pressure sensor for IPC measurements. Applying IPC garments first involved enclosing the limb fiom toes to upper thigh level in a doublewalled, single-compartment-type garment, which was periodically inflated by an air pump (Solo Pro Pump, MJS Healthcare Ltd, Luton). The garment pressure was set to 40 mmHg inflation and zero mmHg deflation. The compression cycle was set at 90 seconds inflation and 90 seconds deflation. Measurements were also repeated using the same volunteer and a 3 chambered garment system (Multi 3 Pump, MJS Healthcare Ltd, Luton). Three consecutive inflation and deflation cycles were recorded following the attachment of the sensors over a period of about 10-minutes,which was allowed for stabilisation of the recordings and base-line LD readings. The data were analysed by a computerised system (Figure I), which records air pressure (AP), IP and skin blood flow or perfusion of an alternating air pressure device. The system calculates pressuretime characteristic^'^ and analysesthe perfision time integral data’*. Statistical analysis was performed by using a commercially available computer programme (Analyse-It, Analyse-It Software Ltd, Leeds, VK). Differences between various pressures and LD blood flow values over one cycle were analysed using Student’s t-test or the Wilcoxon’s signed rank test depending on whether or not data were normally distributed. A difference was considered significantwhen F0.05.
RESULTS Initially the results obtained were in the form of pressure-time graphs and LDF blood -ion curves, as for example in Figures 2 and 3. Finally they are presented numerically as bar charts with mean and f standard deviation (Figure 4). It has been assumed that the net result of bandage and IPC garment pressures would be additive. This was the case especially in fleshy areas of the leg, namely the calf muscle region. Laser Doppler readings showed a significant increase in blood flow at site (2) when compared with pre-compression and post-compression values. Skin LD levels (Figure 3) integrated over time for the three-chamber garment graded compression were greater compared with those for the single chamber Uniform compression (Figure 2).
Fig 2: A typical graph showing interface pressure, air pressure and laser Doppler recording for single chamber IPC garment. 0 Woodhead Publishing Limited, 201 0 295
Fig 3. Figure 2: A typical graph showing interface pressure, air pressure and laser Doppler recording for three-chamber IPC garment.
100
rza c
-
h
T
80-
Y n
&
40-
T
T
Y
2
zo0-t
1
Bandage
IPC
Bandage + IPC
Fig 4. Bar chart showing interface pressures measured on three different sites using a single chamber leg garment, It has also been observed that only 5 out of 12 nurses generated a required negative gradient fiom ankle to knee when bandaging the same leg, the remainder generating null or reverse gradient. This seems to c o d i that the sub-bandage pressure produced in vivo depends largely upon the technique of the bandager. Additionally, contact pressures measured on the skin using IPC alone matched the air inflation pressures. Thus, variations in pressure and gradient may be minimised by the selective use of IPC devices in place of compression bandaging, as the former can be used with confidence even by an inexperienced user.
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CONCLUSIONS Pneumatic intermittent compression devices have been used in many clinical situations. These include prophylaxis of deep vein thrombo~is’~, treatment of peripheral arterial disease” and venous leg ulcers”, reduction of flexion deformities22 and limb oedemau. Reduction of oedema benefits diffusion of oxygen as well as other nutrients in tissues, and it is thought to be an additional reason for improved healing rates of leg ulcers24. Compression bandages have long stood the test of time and will remain, for many patients, the best treatment for leg ulcers. However, in many cases, such as elderly patients who are unable to cooperate in a regimen of exercises or who are confined to bed, IPC therapy may offer an advantage. A number of studies have reported that the effectiveness of IPC may be significantly improved by the simultaneous use of The main purpose of this study was to investigate graduated elastic whether the pressure of IPC garments applied on top of compression bandages is additive. We also assessed the effect of two different modes, that is, intermittent graded compressionand uniform compression on tissue perfusion. The findings of this short study raise a number of issues. Intermittent pneumatic garment pressures correlate with leg interfwe pressures, but they are sensitive to local bone/muscle presence. During IPC alone there is a net increase in skin tissue blood flow/perfusion. There is a need for caution against the use of high air pressures in IPC systems when used in conjunction with high compression bandaging or hosiery, since the combined pressures could cause occlusion in some patients. It is also important to remember that this study was limited to one subject and generalisation can therefore not be made. However, the results indicate the need for a further study using a larger group of subjects.
ACKNOWLEDGE1)IENTS
This study was partly supported by an unrestricted and unconditional grant fiom MJS Healthcare plc of Luton (UK). REFERENCES 1 S Nikolovska, A Arsovski, Damevska, Gocev G, L Pavlova, ‘Evaluation of two different intermittent pneumatic compression cycle settings in the healing of venous ulcers: a randomized trial’, Med Sci Monit, 2005 11 337-343. 2 D H Pfizenmair, S J Kaveros, D A Liedl, L T Cooper, ‘Useof intermittent pneumatic compression for treatment of upper extremity vascular ulcers’, Angiology, 2005 56 417422. 3 S Rajendran, A J Rigby, S C Anand, ‘Venousleg ulcer treatment and practice - part 3: the use of compression therapy system’, J Wound Care, 2007 16 157-159.
4 K Feben, ‘How effective is training in compression banCommunity Nurse, 2003 8 80-84.
techniques?’, Br J
5 A Satpathy, S Hayes, S R Dodds, ‘Is compression bandaging accurate? The routine use of interface pressure measurement in compression bandaging of venous leg ulcers’, Phlebology, 2006 21 36-40. 0 Woodhead Publishing Limited, 201 0 297
6 R A Logan, S Thomas, E F Harding,G H Collyer, Wound Cure, 1992 123-26. 7 A Satpathy, S Hayes, S R Dodds, ‘Measuring sub-bandage pressure: comparing the use of pressure monitors and pulse oximeters’, J Wound Care, 2006 15 125-128.
8 W J Gardner, ‘Circumferential pneumatic compression’,J A M 1966 196 117-119. 9 M Clarke-Moloney, G M Lyons, P E Burke, D O’Keeffe, P A Grace, ‘A review of technologicalapproachesto venous ulceration’, Crit Rev Biomed Eng, 2005 33 5 11-516. 10 P D Coleridge-Smith, J H Hasty, J H Scurr, ‘Sequential gradient pneumatic compression enhances venous ulcer healing: A randomized trial’, Surgery, 1990 10 ( 5 ) 871-875. 11 G Mulder, J Robison, J Seeley, ‘Study of sequential compression therapy in the treatment of non-healing chronic venous ulcers’, Woundr 19902 111-115. 12 F Allenby, L Boardman, J J Pflug, J S Calnan, ‘Effects of external pneumatic intermittentcompression on fibrinolysisin man’, L m e t 1973 ii 1412-1414. 13 T J Tamay, P R Rohr, A G Davidson, M M Stevenson, E F Byars, G R Hopkins, ‘Pneumatic calf compression, fibrinolysis, and the prevention of deep venous thrombosis’, Surgery 1983 88 489-496. 14 A Zelikovski, I Ben-Tov, A Koren, E Stelman, M HaddaD. ‘Veno-Press - A new sequential intermittent pneumatic device for the prevention of perioperative deep vein thrombosis’, Isr JMedSci 1996 32 1335-1337. 15 S K Kakkos, G Szendro, M GriiKn, M M Sabetai, A N Nicolaides, ‘Improved hemodynamic effectiveness and associated clinical correlations of a new intermittent pneumatic compression system in patients with chronic venous insufficiency’. J Vasc Surg 2001 34 915-22. 16 A D Tayor, R J Taylor, ‘A comparison of sub-bandage pressures produced with two multi-layer bandaging systems’, J Wound Care, 1999 8 444-448. 17 S V S Rithalia, M Gonsalkorale, ‘Assessment of alternating air mattresses using a h e - based interface pressure threshold technique’, J Rehabil Res Develop, 1998 35 225-230. 18 S V S Rithalia, L Russell, ‘Evaluationof alternating pressure air mattresses using a time based pressure threshold technique and laser Doppler micro-vascular perttSion measurements on the heel’, EPUAP Review 2003 5 15-16.
19 D Pew, S V Schmiedeberg, A Pier, R E Scharf, A Wehmeier, T RuZicka, J Krutmann, ‘Coagulation factor V gene mutation associated with activated protein C resistance leading to recurrent thrombosis, leg ulcers, and lymphedema: successful treatment with intermittent compression’,JAm Acad Dermatol, 199635 306-309.
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20 E Kalodiki, A D Gianuoukas, ‘Intermittent pneumatic compression (IPC) in the treatment of peripheral arterial disease (PA0D)- a useful tool or just another device?’, Eur J Vasc Endovasc Surg, 2007 33 309-310. 21 E Z H d a , D E Wright, ‘Chronic leg ulcers: The effect of pneumatic intermittent compression’, Practitioner, 1981 225 189-192. 22 K R Morey, A H Watson, ‘Team approach to treatment of the posttraumatic stiff hand‘, Physical Therapy, 1986 66 225-228. 23 S Grieveson,.’Intermittent pneumatic compression pump settings for the optimum reduction of oedema’, J Tissue Viability, 2003 13 98-1-2. 24 D Hofinan, ‘Oedema and the management of venous ulcers’, J Wound Care, 1998 7 345-348. 25 J A Caprini, J L Chucker, L Zuckerman, J P Vagher, C A Frank, J E Cullen, ‘Thrombosis prophylaxis using external compression’, Surg Gynecol Ubstef, 1983 156
5 99-604.
26 D Hohan, ‘Oedema and the management of venous ulcers’, J Wound Care, 1998 7 345-348.
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PHYSIOLOGICALEFFECTS OF LYCRA@PRESSURE GARMENTS ON CHILDREN WITH CEREBRAL PALSY J. Attard' and S. Rithalia' 'Royal National Orthopaedic Hospital, Stanmoor, UK 'University of Salford, Salford, UK ABSTRACT
Lycraa pressure garments are used in the management of cerebral palsy to enhance proprioceptive feedback, function and mobility (Blair et al, 1995; Edmondson et al, 1999). Investigations regarding their effect on the physiology of the wearers have not yet been carried out. This study aims to establish the changes at the patient-garment interface. Method Seventeen children with cerebral palsy, mean age 9.6 years, were fitted with a garment suitable for their needs. The parameters studies were maximum interface pressure (IP), changes in temperature (T), relative humidity 0, and laser Doppler blood flow (BF) at the patient-garment inMace.
Results Overall mean IP was 13.8mmHg; with average trunk IP 26.9mmHg, upper limbs 11.OmmHg, while lower limbs 11.2mmHg. 75% of participants showed a reduction in BF by an average of 32%. In 25%, BF increased by 19%. T increased in 63% of subjects by an average of 1.8OC, and decreased by 1.1"C in 33%; one child showed no change. RH was reduced in 60% of children by an average of 5.7%, and increased in the other 400h of cases by an average of 3.9%.
IP increased when a number of Lycraa layers on the body increased; it also increased with increased movement and activity, implying the dynamic nature of these garments. The overall decrease in BF is in keeping with the increased pressure; in some cases this was highly dependent on the position of the body in relation to gravity as BF increased when the position of the upper limb improved from an elevated position. The changes in T and RH were lower than what one would expect for such a tight-fitting garment, but the breathable nature of the material used allows for the evaporation of perspiration as activity level andor ambient temperature increases. INTRODUCTION Documentation reporting on the use of dynamic Lycra@garments in the treatment and management of cerebral palsy andor other neurological disorders has been increasing over the past twelve However, there is s t i l l a lot that is not known about these garments. It is not yet known how, if at all, the physiology of a child with cerebral palsy 300 0 Woodhead Publishing Limited, 201 0
is affected through wearing a Lycra@pressure g m e n t ; also, it is not established whether the forces applied by the garments on to the body can be quantified andlor changed by the design of the garment. The aim of this study was to establish the physiological changes brought about at the skin-garment interface in children with cerebral palsy through wearing of Lycra@ pressure garments.
CEREBRAL PALSY Cerebral palsy (CP) is a term recognised in both the medical and educational fields. It defines a group of individuals with similar needs for rehabilitation, educational,medical and social services". CP refers to a heterogeneous group of syndromes dominated by disorders of movement and posture. It is the result of a non-progressive cerebral lesion occurring at or around the time of birth. Because the lesion is central in origin, the motor involvement is often accompanied by other sensory, cognitive or communicative impairments". It is one of the more common conditions that Healthcare professionals like orthotistsand physiotherapists involved in the field of paediatrics must deal with on a regular b a d 2 . Although the cerebral lesion itself is static and non-progressive, the clinical manifestations evolve and change with the child's growth and development, and consequently, so do the child's specific medical, therapeutic and educational needs. Periodic reassessment of the child's needs is therefore necessary in providin overall care to prevent secondary complications and plan for the transition to adulthood%. More than 90% of children with CP live to adulthood, although their life expectancy is largely dependant on the severity and complexity of their conditi~n'~. Employability is also dependant on the severity of the condition, especially cognitive and intellectual ability. However, family support, the quality of educational programmes and community-based training, and technical support can also influence this outcome.
DYNAMIC LYCRA@PRESSURE GARMENTS Dynamic pressure garments are made-to-measure body forming Lycra@orthoses that are highly interactive with the wearer. Each garment is individually designed to address each patient's specific needs. The extent to which the garment covers the patient's body also depends on the patient's needs and may range fiom a simple glove coveringjust the hand and wrist, to a full body suit to include arms, legs and the whole of the trunk. One advantage of Lycra@is that it can be combined with virtually every other natural or manmade fibre, such as cotton, wool, silk and linen, to achieve different grades of stretch and recovery; this provides garments that are able to exhibit the following properties:
0 0
0 0
Lightweight; easytoreinforce; incomparable fit; comfort; good crease recovery; fieedom of movemen%and cosmesis.
Thus Lycra@garments have been beneficial to children with CP. Some documented benefits include 1-9: 0 Woodhead Publishing Limited, 2010 301
0
0 0 0
0 0
Improved proximal stability Improved posture/positionof limb Normalisation of tone Reduced involuntary movements Improved function and independence Enhanced patient handling
AIMS AND OBJECTIVES OF STUDY Although documentation reporting on the use dynamic Lycra@garments has been increasing over the past ten years, there is still a lot that is not known about these garments. Thus the following questions will be addressed during this study:
9 What pressure are we exerting on the body when we fit a child with a pressure garment? 9 How does the magnitude of forces being applied change, when the design of the garment is altered? 9 How is skin temperature changing when a child wears one of these garments? 9 How is surface humidity affected when the garment is worn? 9 How does wearing a pressure garment affect skin blood flow? The ultimate objectives of the study are: 0 quantify the pressure applied by garments on skin; 0 quantify changes in skin temperature, humidity and blood flow during garment wear; and 0 improve understanding of such garments and enable clinicians to better assess patient suitability.
METHOD Approval fiom the Southern Derbyshire Local Research Ethics Committee, where the study was conducted, was obtained before the study got underway. Sixteen children participated in the study, 8 male and 8 females, all having a diagnosis of CP.The ages of the participants ranged between 5.5 and 14.4 years (mean f SD was 9.6 f 2.8) The type of CP that the above subjects were diagnosed with included: 0 0
0 0
Spastic unilateral (7 subjects) Spastic bilated (4 subjects) Dystonia (4 subjects) Hypotonia (1 subject)
The interface pressure (IP) between the skin and gannent was measured using a flexible sensor interface system (RSscan International). This system was custom made x 3.0cm, specifically for this project; it included a flat, flexible sensor measuring 7.5~131 consisting of various cells, feeding into a converter unit which in turn plugged into the USB port of the computer on which the s o h a r e was installed. Temperature and humidity measurements were taken by meaus of data loggers (Gemini "YTAL,K II), run using the Orion Tiny Logger Manager (OTLM) for 302 0 Woodhead Publishing Limited, 201 0
Windows as the host software. The data loggers were able to measure differences in temperature and humidity via a probe, or sensor. OTLM set the loggers up to start logging and then to offload the data from them afterwards. Skin blood flow (SBF) was measured using a laser Doppler blood perfusion monitor (Vasamedics" Laserflo" Blood Perfusion Monitor BPM'). The monitor was connected to the computer via the computer's USB port. The sensor used to monitor the superficial skin blood flow fed data into the monitor, and this data was collated by a voltage data logger; this was then offloaded to the computer's OTLM programme. OTLM recorded the electrical signal produced by the flow of blood in the superficial vessels in the skin, and thus, as for humidity,the units of the raw data were millivolts (mV).
RESULTS The results showed a large variation in mean values. Average IP measured on the trunk was 26.9mmHg, on upper limbs 1l.OmmHg and on lower limbs 11ZmmHg. Temperature increased in 9 subjects by an average 1.8OC, and decreased by an average 1.1"C in 6 subjects. Humidity was reduced in 6 children by an average 5.7%, and increased in 4 by 3.9%. 9 subjects showed a reduction in SBF by an average 32%, while SBF increased by an average 19% in 3 subjects. Results showing average IP measurements on the different body segments and under different number of Lycra layers are shown in Figure 1. The results showing changes in skin temperature, humidity and SBF, with and without garment, are shown in Figures 2, 3 and 4 respectively.
I
I
(a) Fig 2. Average temp& segments.
&%remes
(a) all body segments and (b) comparihg results between body
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I
Fig 3. Average changes in humidity (a) all body segments and (b) Comparing results between body segments.
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DISCUSSION It has been reported that circumferentid pressure less than 30 mmHg is safe to apply'5. This is known as the capillary threshold pressure, and there is a generally accepted consensus among researchers that the application of an external load onto the body below this threshold pressure does not cause tissue damage16. The overall average interhe pressure recorded in this study, taking all subjects and all body segments into consideration, was 13.8mmHg. 90% of all results were below 3ommHg while 8 1% were below 20mmHg. One feature that was not taken into consideration during these pressure measurements was the time factor. This was a limitation of the study. Reports suggest that the time interval over which the pressure is applied to the skin is highly important as localised low pressures applied for a prolonged period of time can be just as damagmg to the skin as localised high pressures applied for a short time". However, even though i n t e e pressure was not measured continuously over a period of time in this study, the results show a very wide range of recorded pressures. This may reflect the author's hypothesis that the pressure applied by the garment is not constaut, and changes as the wearer moves or changes position. Over the course of a normal day, approximately eight hours of garment wear, this high variability of pressure applied to the body, combined with the fact that in 90% of cases the pressure applied is below capillary threshold, may be the reason why the garment is tolerated so well by most wearers. Results of pressure exerted on the body through diffetent number of Lycra@layers show that using a double rather than a single layer actually tripled the average pressure applied. However, where a triple layer of Lycra@was used the average pressure recorded was half that applied by a double layer. This result was unexpected as it was 304 0 Woodhead Publishing Limited, 201 0
thought that logically, the more layers added the higher the pressure applied, but was evidently not the case in this study. Due to the customised and specific design of the garments, where each child was prescribed a garment to address hidher individual needs, a triple layer of Lycra@was only used on the distal end of the forearm and the wrist.One explanation for this relatively low pressure measured under a triple layer may be that the three layers produced a greater tension within the garment itseIf. Therefore, the pressure applied was more at a tangent to the body rather than circumferential, resulting in bridging of the garment and intermittent loss of contact between the garment and the skin. This may imply that as the garment was designed to improve wrist extension, bridging and loss of contact was occurring as the wrist moved into extension as a result of the effect of the garment. Consequently and in a somewhat strange way, this result goes some way to providing evidence that the garment is llfilling its function and positioning the wrist into a more functional extended position. For a patient with a neurological disorder therapy is a learning process, where the central nervous system is trained or re-trained in specific sensory-motor behaviour. To enhance this learning process the individual's sensory-motorsystem needs to be focused on all the sensory information being fed into it from the e x t e d environment. The intensity of the stimulus applied, for example deep pressure through the skin, does not necessarily have to be very large, but it can be increased as necessary provided it does not become painful or cause an adverse reaction". It is not necessary for a stimulus to be independently capable of causing discharge of the motor neurons; sub threshold synaptic effects are sufficient for interactions between the peripheral and central pathways to occur19. Therefore, the assumption may perhaps be made that the pressure exerted by these dynamic pressure garments does not need to be very high to participate in sensory-motor re-education. Temperature affects the conduction velocity of nerves both locally at the site of a stimulus and also generally along the length of the nerve. The central nervous system is at core temperature, which is normally kept constant due to homeostatic processes; therefore the nerves within the CNS always conduct at the same velocity. However, nerves within the peripheral nervous system are dependent on the temperature of the skin and the environment. As a result if a limb is cold the conduction velocity in the peripheral nerves of that limb falls drasticall with a factor ranging from 1.2 to 2.4 ms-' for every 1"C drop in cutaneous temperature . Muscle tissue is responsible for the majority of an individual's mass and energy requirements. The intensity of force exerted by skeletal muscles tends to be independent of temperature or to have a low response to changes in temperature. For that reason an individual is capable of generating the same muscle force regardless of hidher body temperature. This thermal independence becomes significant in certain static situations, such as standing, crouching and hanging'.Quite the reverse is seen during a situation involving body movement, where the most significant factor is the rate of application and removal of the force. Contractile rate processes within muscle, such as the time to peak twitch tension, the rate of twitch relaxation, the maximal velocity of shortening of a contracting muscle, and the maximum power output during contraction have a distinctly positive thermal dependence; the speed of muscle activity is very much slower at low temperatures while all contractile rate processes are accelerated by an increase in temperature2'. In the present study the changes in skin temperature that occurred after wearing the garment were not statistically significant. However, it may be worth noting that the temperature increased in 64% of all the measurements taken, and the overall effect of the pressure garments was a slight increase in skin temperature. Could this rise in
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temperaturebe a contributory factor to the way these garments work? Could even such a slight rise in temperature contribute to accelerating the speed of muscle contraction, thus making the contractile rate processes more efficient? This would support the belief among therapists and clinicians thatwarmth has a therapeutic effect on the body. The results demonstrate thatthere is no significant difference between the amount of humidity on the skin before and afker putting on the garment. Thus, no strong conclusions can be drawn from the results in changes in humidity levels on the skin. However, the indications are that the changes in skin humidity are probably not due so much to the pressure applied by the garments but rather to the amount of humidity in the environment. Previous studies have shown that the application of external pressure on the skin brings about a reduction in superficial blood flow”. The results of this study support these findings. However, 25% of subjects demonstrated a mean increase in SBF when the garment was put on. These subjects had a diagnosis of spastic unilateral cerebral palsy with dystonia. One of their problems was that they could not control their affected upper limb and when free, the arm would move involuntarily to an elevated and abducted position level with their shoulder or head. When they put on the garment the position of the upper limb immediately changed and the arm moved down to the side of the body without them having to physically hold it there. Thus, when the blood flow was measured before the garment was put on, this was done with the arm in its elevated position. With the garment on, the arm was in a more natural position and thus the blood flow to the arm increased probably due to the effect of gravity.
CONCLUSIONS In conclusion, the main findings of this study may be summarised as follows: IP varies according to body segments. 90% of IP results are lower than 30mmHg, reducing the risk of tissue damage. On average IP tripled in areas where double layer of Lycraa was used. 0 IP applied by triple Lycra@ layer (applied only on dorsal wrist) was half that applied by double layer, suggesting possible loss of contact (bridging) during wrist extension. IP generally varied with increased activity, implying dynamic nature of garments.
Temperature and humidity changes more likely to be attributed to environmental factors. SBF increased with application of pressure. REFERENCES
1 E Blair, J Ballantyne, S Horsman, P Chauvel, ‘A study of a dynamic proximal stability splint in the management of children with cerebral palsy’, Dev Med and Child Neurol, 1995 37 544-54. 2 N Hylton, C Allen, ‘The development and use of SPIO Lycra compression bracing in children with neuromotor deficits’, Puediutr Rehubil, 1997 1(2)109-16.
3 J Edmondson, K Fisher, C Hauson, ‘How effective are Lycra suits in the management of children with cerebral palsy?’ APCP J, 1999 90 49-57. 306 0 Woodhead Publishing Limited, 201 0
4 J M Gracies, J E Marosszeky, R Renton, et al, ‘Short-term effects of dynamic Lycra splints on upper limb in hemiplegic patients’, Arch Phys Med Rehab, 2000 81 1547-55.
5 D J Rennie, S F Attfield, R E Morton, et al, ‘An evaluation of Lycra garments in the lower limb using 3-D gait analysis and functional assessment (PEDI)’, Gair Poslure, 2000 12 1-6. 6 J H Nicholson, R E Morton, S Attfield, D Rennie, ‘Assessment of upper limb function and movement in children with cerebral palsy’, Develop Med Child Neurol, 2001 43 384-91. 7 K Corn, C Imms, G Timewell, et al, ‘Impact of Second Skin Lycra splinting on the quality of upper limb movement in children’, Br J Occ Ther, 2003 66(10) 464-72.
8 V b o x , ‘The use of Lycra garments in children with cerebral palsy: A report of a descriptive clinical trial’, Br J Occ Z’her,2003 66(2) 71 -77. 9 J Attard, S Rithalia, ‘A review of the use of Lycra pressure orthoses for children with cerebral palsy’, Znt J Z’her Rehab, 2004 ll(3) 120-26. 10 K B Nelson. In: K Swarman (Ed), Cerebral Palsy in Paediatric Neurology Principles and Practice, CV Mosby 1989 363-71.
11 P S Eicher, M L Batshaw, ‘Cerebral Palsy’, Pediatr Clin N A m , 1993 40 537-51. 12 J M Wilson. Cerebral palsy. In: S K Campbell (Ed). Pediatric Neurologic Physical Therapy. 2ndedition. New York: Churchill Livingstone, 1991 301. 13 T E Strax, M A Alexander, K M Sobus. Cerebral palsy. In: M Grabois, et al (Eds). Physical Medicine and Rehabilitation - The Complete Approach. Massachusetts: Blackwell Science, Inc. 2000 1401-13.
14 P M Evans, S J Evans, E Alberman. Cerebral palsy: why we must plan for survival (abstract). Arch Dis Child, 1990 65 1329-33.
15 E C Campion, D C Hoflhan, R P Jepson, ‘The effects of external pneumatic splint pressure on muscle blood flow’, Aust mJ Surg, 1968 38(2) 154-157. 16 S V S Rithalia, ‘Pressure sores: Methods used for the assessment of patient support surfaces’, Clin Rehabil, 1991 5 323-329. 17 J B Reswick, J E Rogers, Experience at Rancho Los Amigos Hospital with devices and techniques to prevent pressure sores. In: R M Kenedi, J M Cowden, J T Scales (Eds). Bedsore Biomechanics. Baltimore: University Park Press, 1976,301-3 10.
18 E H Littell, Neurological training and retraining. In: R M Scully, M R Barnes (Eds). Physical Therapy. Philadelphia: J.B. Lippincott, 1989: 796- 824.
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19 F A Harris, Facilitation techniques and technolo ‘cal adjuncts in therapeutic exercise. In:J V Basmajian (Ed). Therapeutic Exercise. 4it edition. Baltimore: Williams & Wilkins 1984:110-178. 20 P Dioszeghy, E StAlberg, ‘Changes in motor and sensory nerve conduction parameten with temperature in normal and diseased nerve’, Electroen Clin Newo, 1992 85 229-235.
21 A F Bennett, ‘Thermal dependence of muscle hction’, Am J Physiol, 1984 247 R217-R229.
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EMPIRICAL MODELLING OF ELASTIC PROPERTIES OF PRESSURE GARMXNTS FORIIEALTHCARJC S. Pereira, S.C. Anand, S. Rajendran Institute for Materials Research and Innovation, The University of Bolton, Bolton, UK C. Wood, Baltex Ltd., Ilkeston, UK ABSTRACT The elastic properties of pressure garments are intrinsically related to a number of their mechanical properties and these relationships follow the well known Laplace’s equations. Compression therapy is now a well established method in the management of a number of healthcare conditions and it is basically related to blood flow which in turn is related to a number of variables of the pressure garment. In this research two main applications in healthcare have been investigated: knee braces and pressure garments for the treatment of hypertrophic scars resulting from burns. During this study existing commercial products have been fully analysed and characterised and novel three-dimensional knitted structures with improved properties have been designed, developed and I l l y characterised. A detailed comparison has been carried out between existing and novel materials and the latter have proven to excel in their mechanical and thermophysiological properties as well as their elastic properties by providing a quasi isotropic behaviour. This is of the utmost importance when the compression is required to be uniform in all directions when applied to the limb. Empirical models to predict the interface compression level exerted by these novel materials on the human body have been developed and validated through experimentation.
INTRODUCTION Spacer fabrics are three-dimensional structures that can be engineered to incorporate a wide range of attributes and hence M l specific pre-determined requirements. Knitted spacer fabrics can be produced on both weft and warp knitting machines. Each of the fabric faces can be designed independently, as well as the middle layer (spacer layer), in terms of yams and structures and this will determine the unique individual properties of each fabric [ l f . Spacer fabrics have been studied and developed for a few years now but the number of variables that can possibly be input in their construction gives such a wide range of possibilities that many are still to be developed and exploited commercially. This research focuses mainly on one of the least exploited properties of spacer fabrics: the elastic properties. Consideringthat the best attribute of spacer fabrics is their thermophysiologicalproperties, a combination of these with the elastic properties gave birth to a very important medical application: compression therapy. This research has focused on pressure garments, namely: knee braces and pressure garments for third degree burns. The main objective of this project was to characterise and develop novel threedimensional knitted structures with improved thermophysiologicalproperties to be used in knee braces and burn garments. It was the intention to develop a mathematical model of these structures which relates the tensile properties of each of the different structures with its elastic properties as a way to predict the level of compression on the patient’s limb. 0 Woodhead Publishing Limited, 201 0 309
Two papers have been previously published which discussed the development of novel three-dimensional spacer fabrics for knee braces. In these publications a thorough analysis of the tensile and thermophysiological properties of each of the structures developed was also presented and critically compared with commercially available fabrics for the same end-use [3,4]. This paper deals with the empirical modelling of the elastic properties of the novel three-dimensional fabrics developed during this research for knee braces.
EXPERIMENTAL During this research commercially available fabrics have been fully analysed and characterisedfor their properties for both knee braces and burn garments. Novel three-dimensional knitted fabrics have been developed and analysed with the purpose of fulfilling, if not exceeding, the requirements of such pressure garments. Up to the present moment of writing this paper two spacer fabrics have been identified which satisfy completely the tensile and elastic properties of knee supports. It has also been established that they possess the desirable thermophysiological properties, which is a major achievement as these properties are of the utmost importance in garments that are to be used for long periods of time [5,6]. One of these fabrics, quality 5870, is a warp knitted spacer fabric and the other, quality 3500C, is a weft knitted spacer fabric. The mathematical modelling of these two spacers has also been completed and is described in this paper. At present several knitted spacer fabrics are being developed and characterisedwith an aim to be used as pressure garments for third degree bums. This research work will be reported at a later date.
Materiala Commercially available knee braces and third degree burn garments are currently made from a wide range of materials. A selection of commercial products and fabrics has been fully tested and analysed for their dimensional, thermophysiological,tensile and elastic properties in order to bench mark the optimum properties for such applications. Most of these results have been discussed in previous papers [3,4]. Novel three-dimensional knitted fabrics, both weft and warp knitted, have been designed, manufactured, tested and analysed in order to study their properties for these support/pressure applications. Three-dimensional knitted structures are made of two independent knitted faces which are at the same time interconnected by a spacer yam, providing the third dimension of the material [7]. The three layers are completely independent in terms of yam choice and structure and these provide a very wide range of variables into a single composite, thus presenting opportunities for engineering a single fabric with a range of pre-defined properties and performance [l]. other attributes of these fabrics are [8]: 0 the thickness of the fabric can be engineered as desired depending on the machine type and material selection; 0 different degrees of softness and handle can be designed; different opacity and structure can be used independently on the two faces of the fabric; 0 different materials can be chosen for the two fabric faces and spacer threads; and 0 the fabric can be knitted to shape in weft knitting. 310 0 Woodhead Publishing Limited, 201 0
Knee Braces Commercially available knee braces are currently manufactured fiom neoprene, knitted fabrics, foams or a combination of these. When tested, these have proven to be very uncomfortable; this means that wearers are not able to withstand them for as long as they should, especially when performing physical activity [9,10]. It has also been found that many of these products do not offer the correct compression levels required for knee braces. A number of knitted spacer fabrics have been developed, tested and analysed during this research with view to study their suitability for using as a knee brace material. Of these, two spacers have been identified as having the desirable properties sought after for such supports. These two novel fabrics have been produced by two different methods, weft knitting and warp knitting.
WeftKnitted Spacer The weft knitted.spacer, quality 3500C, was manufhchued on a circular weft knitting machine. The weft knitting machine, with an E20 gauge, and a 30 Inch diameter, was set with an interlock gaiting and a 4.4 mm dial height. Both faces were knitted h m 167dtex polyester and they both use 44dtex Lycra elastomeric yam. The spacer yam used in this fabric was a 0.08mm polyester monofilament. The spacer 3500C was 2.89mm thick and had an area density of 498.6 gm-’. Warp Knitted Spacer The spacer quality 5870 was a warp knitted fabric and polyester filament and Lycra yams were used on both faces; the monofilament used as the spacer yam was also polyester. Both faces were of solid construction. This fabric was 2.82 mm thick and had an area density of 46 1.3 gm-2. Test methods The dimensional, tensile and thermophysiological properties of most of the materials referred to in this paper have already been discussed in previous publications [3,4], however, the tensile properties will be presented again in this paper as the authors find it relevant when establishing relationships between tensile and elastic properties of these fabrics. Testing of Tensile Properties The tensile tests were performed on an Instron Tester Model 4303 and the testing parameters used were as follows: - distance betweenjaws: 1Ocm; - speed200mld~; load cell: 25kN. Due to the shortage of material of the commercialproducts the specimen dimensions used were reduced to 15cmx2.5cm. The test specimens for the spacer fabrics were cut to the same dimensions as for the commercial products in order to make a direct comparison of the mechanical properties.
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From the lodelongation curves obtained for each specimen, its tenacity (Ntex-'), breaking extension (%), modulus (N) and specific modulus (Ntex-') were determined in the three major directions, i.e. machine direction (MD), crossdirection (CD) and 45'. Testing of Elastic Properties The elastic properties of all the materials were determjned by following the British Standard BS7505 on a Hounsfield instrument model HSKS. From these tests it was possible to obtain the values for tension ratio (tr), working extension (we) and differential extension factor (def), all expressed as a percentage. These properties are used to determine the compression characteristics and l i t s of suppodpressure garments. According to BS7505, a bandage that is used to restrict movement and provide intermittent sub-bandage pressure is classified as a 'Light Support Bandage', and is given the designation Type 2. It has been concluded fIom previous work that knee braces are used as support garments and should provide a compression to the knee between 14 and 1 7 d g . The fabrics aimed to be used as knee supports have been tested according to the parameters for a Type 2 bandage.
RESULTS AND DISCUSSION Tensile Properties The tensile properties relevant for the modelling are the fabric's tenacity (Ntex-'), breaking extension (%) and specific modulus (Ntex-'). Table 1 shows the values of the tensile properties for the novel spacers developed for knee braces: warp knitted fabric, 5870, and weft knitted fabric, quality 3500C. It can be seen from this table that the results for both knee brace fabrics are quite similar in the cross direction and 45 degrees; however, significant differences exist in the machine direction. This is due mainly to the two entirely different manufacturing techniquesused in the construction of these two fabrics, as one is warp knitted and the other is weft knitted. A knee brace in its basic form is a tubular structure around the patient's join$ therefore, the authors have considered that the cross direction of the fabric is the most important one to be analysed. The cross direction represents the circumference of the knee. Taking this into consideration it can be seen f h m Table 1 that these two fabrics possess identical tensile properties in the cross-direction, CD. Table 1. Tensile properties. Novel Spacers Fabric Quality Direction Tenacity (Ntex-') Breaking Extension (?h)
Modulus (Ntex-')
5870
MD 0.030
255.8 0.0019
CD 0.028 210.7 0.0021
45O 0.024 191.1 0.0023
MD 0.015
193.3 0.00124
3500C CD 0.028 234.1 0.00214
45"
0.025 168.2 0.00197
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Elastic Properties
Table 2 shows the results of the elastic properties of the novel knitted spacer fabrics developed for knee braces according to the British test method BS7505. Using the statistical software package SPSS, it was possible to establish a relationship between the tensile and elastic properties of the materials studied in this work. This has been carried out for the cross-direction of the material only as this is considered to be the relevant direction for compression in a knee brace. It was established that there is a good correlation between the tension ratio (tr), working extension (we) and differential extension factor (def) with both specific modulus (m) and breaking extension (be). A multi-linear regression equation for the dependent variables tr, we and def with the independent variables be and m was established for each material and the equations are shown in Table 3. It is not feasible to establish the general equation for the two fabrics i.e. 5870 and 3500C. This is due to the fact that the two fabrics use different yams, have different structures and have been finshed using different processing routes. Furthermore, warp knitting and weft knitting techniques are completely different and produce different structures with different characteristics. Table 2. Elastic properties. Novel Spacers
Fabric Quality Direction Tension Ratio (%) Working Extension (%) Differential Extension Factor (%)
MD 69.2 28.62 1.652
5870 CD 70.3 25.09 1.562
Novel Spacers
3500C
MD 69.0 2821 1.552
Multi-linear Regreasion
Wlity
5870
45O 68.4 25.4 1.506
t1=-0.118be-2 1029.412m+139.250 we=O.15 lbe+l6307.647m40.885 def=0.001be-149.333m+1.595 td.03Obet143 1.817m61.485 w~O.049be-2365.18lm+21.721 deFO.002be+62.7791n+1.060
3500c CD 71.5 28.07 1.696
45O 69.3 25.26 1.544
Correlation Coefficient 0.31 0.88 0.99 0.80 0.57 0.78
Empirical modelling The interface pressure induced by a compression or support garment is defined by Laplace’s equation as below:
p=- T.n.K
c.w
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Where,
P - Pressure exerted by the bandage [mmHg] T - Tension applied by the bandage [Kgfl n - Number of Layers C - Limb circumference [cml W - Width of bandage [cm] K = 4620 Equation (1) illustrates that the pressure is directly proportional to the amount of tension applied and the number of layers and indirectly proportional to the limb circumference and Width of the bandage [11,12]. In this study the fabric width W = 2.5cm, the number of layers N = 1 and 1 N 4.1019 Kgf. Using Laplace Equation based on circumference (Equation l), theoretical pressures in m m H g were calculated for each load values for the determined circumference values (Table 5). Using Table 5, a graph was created to illustrate the inversely proportional relationship between pressure and circumference which is shown in Fig.1. For knee braces the maximum circumference of the largest part of the knee would be around 5Ocm.
t
OICC
t W
N 3N 4N
5N *-6N
+7N
-.
8N
BN 101
io
20
25
30
55
40
45
55
Clmumfamc. (em)
Fig.1 Theoretical pressure versus circumference (2.5cm length).
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Table 5 . Theoretical pressure (mmHg) versus circumference,C (cm), using Laplace Equation (2.5cm length) at different tensions T O . \TN)
2N
3N
4N
5N
6N
7N
8N
9N
1ON
c(m& 10
15 20 25 30 35 40 45 50
37.6758 25.1172 18.8379 15.0703 12.5586 10.7645 9.4190 8.3724 7.5352
56.5138 37.6758 28.2569 22.6055 18.8379 16.1468 14.1284 12.5586 11.3028
75.3517 50.2345 37.6758 30.1407 25.1172 21.5291 18.8379 16.7448 15.0703
94.1896 113.0275 13 1 A654 150.7034 62.7931 75.3517 87.9103 100.4689 47.0948 56.5138 65.9327 75.3517 37.6758 45.2110 52.7462 60.2813 50.2345 31.3965 37.6758 43.9551 26.9113 32.2936 37.6758 43.0581 23.5474 28.2569 32.9664 37.6758 20.93 10 25.1 172 29.3034 33.4896 30.1407 18.8379 22.6055 26.3731
169.5413 1 13.0275 84.7706 67.8165 56.5138 48.4404 42.3853 37.6758 33.9083
188.3792 125.5861 94.1896 75.3517 62.7931 53.8226 47.0948 41.8620 37.6758
Knee Braces For a knee brace the optimum pressure has been determined as 15.5 d g . The tensions (N) were calculated for this optimum pressure for different circumfaences (cm) and are presented in Table 6[a]. Using the data from Table 5 the tensions (N) were calculated for the optimum pressure of 15.5 mmHg (see Table 6[a]). It can be observed from Table 5 that for a circumference of lOcm and a tension of 2 N a pressure of 37.6758 mmHg would be obtained, theoretically. Therefore, using the transposition method, and for an ideal pressure of 15.5mmHg, T= (15.5 x 2) / 37.6758. The same method was used to calculate the tension to be applied for each of different circumferences to achieve the ideal pressure of 15.5 mmHg on the limb.
Warp knitted Spacer 5870 Five specimens were tested for their tensile properties (as described in ‘Test Methods’). The dimensions of these specimens were 150mmx25mm and only the cross direction tensile properties were investigated as this would be the direction of application of compression to (around) the limb. The average values for the relationship between displacement and load were calculated and are plotted in Fig.2. It can be seen fiom Fig.2 that there is an almost linear relationship between displacement and load. The linear regression equation and correlation coefficient (R2)were calculated and a straight line relationship was established as shown in Fig.2. The changes in length versus circumference werc calculated using the equation y = 3.6125~- 2.6909 determined fiom the displacement-load graph (Fig. 2), for an optimum pressure. of 15.5mmHg. The fina.l results can be seen in Table 6[b]. In terms of manufacture of medical devices it is important to know the percentage change in length required. This was calculated using the expression: %change in length = (change in length/circumference)*100 It was then possible to predict the percentage reduction in circumference required when manufacturing the knee braces, considering that the tested specimens were 25mm wide specimen and that a knee brace on average would be 225mm wide (in this case it is the length of the brace). In order to obtain these values the percentage change in length values were divided by 25 and multiplied by 225. These values are given in Table 6[c]. 0 Woodhead Publishing Limited, 2010 315
60
50
40
I
1-
d
20
10
0
2
4
a
a
10
12
14
ie
-wl Fig2 Linear relationshipbetween displacement and load for 5870. From Table 6[c] it is possible to plot a graph (Fig.3) which illustrates the relationship between limb circumference and percentage reduction of material’s width dimensions required when manufacturing a knee brace. From this graph a best fit third order polynomial regression equation and its correlation coefficient were determined (seeFig.
3).
From the polynomial regression equation, y = 0 . 0 0 0 6 ~-~0.0722~’ + 2 . 8 8 5 ~19.292, it is possible to calculate the percentage reduction in circderence required when producing a brace. These values are illustrated on Table 6[d] and can be compared with actual values calculated h m the formulae.
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18
v
-
-
0.00Wx’. 0 . 0 7 2 2 ~+ ~2 . 8 8 5 ~ 10.292 . R* 0 9958
20’
.
P 10
x
-
_.
____
I _
20
10
.-
I
30 Llmb Clrcutwbmnco
40
_-
50
80
Fig 3. Percentage reduction in circumference required for optimum pressure (15.5 mmHg) for 5870.
Circumf erence ( 4
[a1 Tension
0
PI Changein Length (mm)
:d]
[GI
Change in Length foroptimum
Pressure (“h) (25mm length)
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% Reduction in
Circumference Required (225mm length)
YODifference hedicted % Reduction
Actual vs. hedicted Values
Weft Knitted Spacer 3500C From the tensile tests it was verified that this spacer also exhibits a linear relationship between displacement and load, and the linear regression equation and correlation coefficient (R') were calculated (Fig. 4). 70 I
- - __
-
-_
- --
_.
50
10
0
-10
' Load (N)
Fig. 4 Linear relationship between displacement and load for 3500C. The same set of calculations was performed for the weft knitted spacer 3500C as it is to be used for the same application, knee braces, and therefore the same amount of pressure is required, 15.5 mmHg. The results are shown in Table 7. The percentage reduction in circumference required for optimum pressure is plotted for different limb circumferencesin Fig. 5.
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Fig. 5 Percentage reduction in circumference required for optimum pressure (15.5 d g ) for 3500C.
Table 7. [a] Tension versus circumference for optimum pressure of 15.5 mmHg (25mm length); [b] Change in length versus circumference (25mm length); [c] Percentage reduction in circumference required for optimum pressure (225m); [d] Percentage reduction in circumference required determined h m the polynomial equation (225mm length) for 3500C. circumf emce (cm)
[a]
[d]
[CI
0
Change in L.-ensth (mm)
Change m Length for Optimum Pressure (%) (25mm length)
0.8228 1.2342 1.6456 2.0570 2.4684 2.8798 3.2912 3.7026 4.1140
-0.0510 1.4820 3.0150 4.5480 6.0810 7.6140 9.1470 10.6800 12.2130
-0.0510 0.9880 1SO75 1.8192 2.0270 2.1754 2.2867 2.3733 2.4426
Tension
10 15 20 25 30 35 40 45 50
bl
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% Reduction
%
in
Difference
Circumference Required (225mm length) -0.4590 8.8920 13.5675 16.3728 18.2430 19.5789 20.5807 21.3600 21.9834
Actual vs.
Predicted % Reduction
Predicted Values
0.02 7.94 13.26 16.49 18.18 18.83 18.97 19.14 19.85
95.86 10.70 2.29 0.74 0.37 3.84 7.81 10.40 9.70
General Relationships The predicted values for the percentage reduction in circumference for a general knee brace mauufkctured fiom a novel spacer have been determined by analysing simultaneously the values given in Table 6[c] for 5870 and Table 7[c] for 3500C. A graph has been plotted which shows the curves produced fiom these values (Fig. 6). A third curve has been plotted using the combined values h m the two novel spacers (Poly, combined curve, Fig.6) and a best fit line has been generated for this curve, using a polynomial regression (2" order). The polynomial regression catl also be described by the equation y=-0.0175x2+1.5006x-10.343 and has a correlation coefficient, R2,0.9599. From this equation the general predicted reduction values for the circumference of a knee brace have been calculated and are shown in Table 8 alongside with the individually calculated values for 5870 and 3500C.The percentage differences between the predicted and calculated values are also given in Table 8.
//A/
Fig. 6 Combined plot of different curves.
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Table 8.Percentage reduction in circumference required for optimum pressure. Circumference (cm)
YOReduction Predicted YO YO in in % Difference Difference Circumference Circumference Reduction Between Between Required Required General Predicted predicted (5870) (35OOC) General General and and Calculated Calculated ‘YOReduction
10 15 20 25 30 35 40 45 50
2.53 10.61 14.64 17.06 18.68 19.83 20.70 21.37 21.91
-0.46 8.89 13.57 16.37 18.24 19.5789 20.58 21.36 21.98
2.9 8.23 12.67 16.23 18.93 20.74 21.68 21.75 20.94
5870 14.98 22.42 13.48 4.86 1.32 4.58 4.75 1.761 4.43
3500C 734.64 7.46 6.62 0.84 3.74 5.93 5.35 1.81 4.76
CONCLUSIONS Of all the novel products developed during this research, two knitted three-dimensional fabrics have been found to possess the desirable thennophysiological, mechanical and elastic properties sough after in materials for knee braces; these were the warp knitted spacer 5870 and the weft knitted spacer 3500C. It has been established that knee braces are required to offer a support of around 15.5mmHg to the patient’s limb and for testing purposes these have been compared to a type 2 bandage according to BS7505.A knee brace in its basic form has a tubular shape and therefore the cross-direction of the material has been considered for analytical purposes in this paper. This paper focuses on the mathematical modelling of the relationship between the mechanical and elastic properties of these 2 novel materials. It has been found that both materials offer a quasi linear relationship between load and displacement when tested for their tensile properties. The two novel spacers also offer very similar curves for the relationship between limb circumference and percentage reduction in material’s width during manufacture in order to obtain optimum compression of 15.5 mmHg around the knee. REFERENCES 1 Anon., Karl Mayer, Spacer Fabrics - An Alternative to Laminated Foam Fabrics (April 1992). ‘Verkauf Information Service, N. 656,Karl Mayer Textilmaschinenfabric GmbH,Obertshausen, Germany.
2 S C Anand, ‘Knitted three-dimensionalstructures for technical textile applications’, int conf Technical Textiles, New Delhi, India,11-13November 2006. 3 S Pereira, S C Anand, S Rajendran and C Wood, ‘Novel 3D knits for knee braces’, Knitting International, November 2006 32-35. 0 Woodhead Publishing Limited, 2010 321
4 S Pereira, S C Anand, S Rajendran, and C Wood, ‘A study of the structure and properties of novel fabrics for knee braces’, Jof Ind Textilles,2007 36(4) 279-300. 5 L Kaya, K Kivang, W Dalay, S AcartOrk and E Atila, Pressure Therapy in the Treatment of Advanced Post-Burn Hypertrophic Scar: a Comparative Study of Clinical
Evaluation, Photography and Ultrasonography,Annals of the Mediterraneau Bums Club, 7: 4. Online, www.medbc.com 1994. 6 J Johnson, B Greenspan, D Gorga, W Nagler and C Goodwin, ‘Compliancewith pressure garment use in bum rehabilitation’,J of Burn Care and Rehabilitation, 1994 15 181. 7 U Wollina, M Heide, W Muller-Litz, D Obenauf and J Ash, ‘Functional textiles in prevention of chronic wounds’, Wound Healing and Tissue Engineering, Current Problems in Dermatology, 2003 31 82-97. 8 M Legner, (2001), ‘Medical textiles with specitic characteristics produced on flat knitting machines’, S.C. Anand (ed.) Int C o d Medical Textiles-Proceedings, August 1999, Bolton, UK. Woodhead Publishing and CRC Press, England, 49-50. 1999.
9 V T Bartels, K H Umbach, ‘Physiological demands on materials for bandages’, 6th Dresden Text Conf; 19-20 June, Germany 2002. 10 V T Bartels, ‘Warp knitted spacers versus neoprene’, Kettemvirk Praris, 112002 2022.
11 G Bennett and M Moody, Wound Care for Health Professionals, Chapman and Hall, London, 96,1995. 12 S Thomas, The use of the laplace equation in the calculation of sub-bandage pressure. Online, www.worldwidewounds.com/2OO3/june/Tho~placeBandages.html2003.
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INVESTIGATION OF ELASTIC PROPERTIES OF MULTIAXIAL WARP K " I X D BANDAGES M.-IN, D KOCAK,S I MISTIK, M UZUN, Marmara University Technical Education Faculty Textile Department 8 1040 Istanbul/Turkey ABSTRACT The production of technical textiles is an expanding market. New production methods have also been developed for technical textiles rather than the classical production methods. It is now possible to produce a very wide spectrum of fabric structures in warp knitting technology. Bamboo and soyabean fibres are relatively new regenerated fibres and have special properties, they are also used in medical applications because of their anti-bacterial properties. In this study bandages h m SoyabedolyesterElastomeric yarn and Bamboo/Polypropylene/Ela.stomericyarn bandages were produced by using multiaxial warp knitting method. Multiaxial bandages were tested in terms of tensile strength, elongation and elastic properties.
INTRODUCTION
Bamboo fibre is a regenerated fibre and has some special properties. It is softer and more absorbent than cotton, biologically degredable and anti-bacterial. Soyabean fibre is also regenerated fibre which has good physical properties and good for human health. Soyabean and bamboo fibres have been used for medical purposes and in baby clothing. Plain woven and circular knitted fabrics are used for classic medical bandages. Generally highly twisted cotton and viscose fibres are preferred for the bandages. In this study multiaxial warp knitting fabrics and bamboo, soyabeau fibres were used as alternative to classic medical bandages. Three dimensional structures of multiaxial warp knitted fabrics have been recently developed for multidirectional reinforcement of composites. Multilayen of linear yams are assembled in warp (OO), weft (90") and bias (M) directions to provide in-plane reinforcement in specific directions and they are stitched together by knitting yams to provide structural integrity and through the thickness reinforcement [1,2,3,4,5]. MATERIALS AND METHODS In this study two material groups were chosen and numbered from 1 to 4. For number 1 and 2 bamboo, polypropylene and elastomeric yams, for number 3 and 4 soybean, polyester and elastomeric yams were used. The linear density of all yarns were 100 tex. Multiaxial warp knitted structures were produced from these yarns, directions of the yarns are given in Table 1. Finally multiaxial warp knitted bandages were stitched with polyester thread for the structural integrity.
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Table 1. Yam direction and fibre type of multiaxial warp knitted bandages
Samples 1 2 3
4
FibreBamboo Yarn Elastomeric Yarn Polypropylene Yam Bamboo Yarn Elastomeric Yam Polypropylene Yam soyabean Yarn Elastomeric Yam Polyester Yam Soyabean Yarn Elastomeric Yarn Polyester Yarn
YarnDirection +45" 90" -45" -45" 90' +45" +45" 90"
-45' -45"
90" +45"
The name of the elastomeric yam used in this work is Gippe, the core of this yarn is elastomeric y a m the outer surface of the yarn is twisted by cotton fibre. The tensile strength, elongation and elastic properties of the bandages were carried out. W o n 441 I test machine was used for these analyses. Tensile strength and elasticity tests were applied on 90" yarn direction. Elasticity test loads were applied from 1 kgf to 5 kgf and the elastic properties of the bandages were determined.
RESULTS The tensile strength and elongation properties of the multaxial warp knitted bandages are given in Table 2. Table 2. Tensile strength and elongation properties of the multiaxial warp knitted bandages Samples Tensile Strength
Elongation (YO)
1 2
17.1 9.7
350% 179%
3
5.5
4
9.6
67% 85%
As can be seen fiom Table 2, fmt two samples (1,2) have higher tensile strength and elongation than other two (3,4) bandages. The elongation properties of the bandages which contain bamboo and polypropylene fibres are better than soyabean and polyester fibre fabric.
Elastic properties of samples 1 and 2 are given in Figure 1. Figure 2 shows the elastic properties of samples 3 and 4.
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96 94 92
s i. 90
g
88
u)
L? 86 W
a2 2
1
3
5
4
Applied Load, kgf
Fig 1. Elastic properties of sample 1 and 2. As can be seen from the Figure 1, elastic properties of the bandages 1 and 2 decrease as the load applied increases.
95 I
-3 0
I
75 i -
_
1
2
3
4
.
_
_
4
~
5
Applied Load, kgf
Fig 2. Elastic properties of samples 3 and 4. Elastic properties of samples 3 and 4 also decrease by increasing the load applied. All samples show similar trends as regards their elasticity.
CONCLUSIONS Elastic properties of all bandages decreased as the load applied increased. The most elasticity was obtained by using 1 kgf load. But increasing the load applied, elastic properties of the bandages decreased. Using 45" y a m directions in stead of +45" and -45" directions improve the tensile strength of the bandages. Bamboo containing bandages have shown beter tensile strength than other samples. Fibre types apart from elastomeric yam do not affect the elastic properties of the bandages. 0 Woodhead Publishing Limited, 201 0 325
However, bandages can be produced by using Werent yarn directions (40°,60” etc). Different y a m direction might improve the elastic properties of bandages. REFERENCES 1 BambroTex Technical Guidance Documents, 2003. 2 http://www.bamboosa.com
3 Q Shen, D Liy Y Gao, Y Chen, ‘Surface properties of bamboo fibre and comparison with cotton linter fibres’, Colloids andswfaces By2004.
4 http://www.swicofl.com 5 G Wu Du, F KO,‘Analysisof Multiaxial Warp-Knit Preforms For Composite Reinforcement’, CompositesScience and Technology, 1996 56.
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PART V IMPLANTABLE MATERIALS
IMPLANTABLEMATERIAL& AN OVERVIEW S Rajendran Institute for Materials Research and Innovation University of Bolton, Bolton BL3 SAB, UK
INTRODUCTION Textile materials are used in a wide variety of applications in healthcare and medicine which include implantable materials for in vivo applications. Vascular grafts, artificial ligaments, artificial blood vessels and mesh grafts are typical implantable medical devices, High-tech advances in tissue engineering have enabled researchers to cultivate implantable human organs to the required shape by growing living cells on textile scaffolds.
VASCULAR GRAFTS In 1952 Voorhess et al successfully deposited fibrin withh the interstices of the fabric and found that ingrowth of fibroblasts fiom adjacent soft tissue occur first and then endothelium migration would follow. This finding engulfed researchers to further research and develop vascular prostheses. Vascular grafts are made from a variety of synthetic materials. The majority includes polyethylene terephthdate (PET), expanded PET (ePET), expandable polytetrafluoroethylene (ePTFE) and polyurethane (€‘U). However, PET, ePET and ePTFE are the most common currently available vascular prostheses (Table 1). PET, ePET and ePTFE are highly crystalline which prevents the polymers from hydrolysis. The hydrophobicity of the polymers has important implications in predicting surface interactions with blood and tissue. PET vascular graft (Dacron) was first implanted by Julian in 1957. PTFE (Teflon) was patented by W o n t in 1937 but its medical use began in 1960. The ePTFE, which was discovered by Gore (Gore-Tex) in 1969, graft is non-porous and popularly used for femoro-popliteal and axillo-femoral bypasses. Both PET and ePTFE grafts perform well at large diameters (>6 mm) but not suitable for small diameter (<4 mm) applications. It seems that utilisation of biodegradable polymers is the solution for small diameter vascular grafting. These polymers act as a temporary scaffold through which tissue ingrowth in vivo takes place and eventually the polymers are completely absorbed resulting biological vascular graft. One of the principal criteria for the graft is that the fibrous structure of the paft must have sufficient porosity to allow tissue growth as well as the formation of a thin fibrin based blood clot resistance layer on the inner surface of the graft.
Vascular prostheses are either woven or knitted. Woven graf€sexhibit a high degree of stability in both warp and weft directions, high strength and low porosity (50 - 200 dmin/cm2). Because of their low porosity, the prostheses are used without precoating in large-caliber, high-flow arteries. Since woven structure provides greater strength they are, therefore, more suitable for high stress locations such as the thoracic aorta. Knitted prostheses are mainly warp knitted velour structures. In knitted structures, the strength and porosity of the graft is influenced by loop configuration. Knitted grafts generally have a high porosity (2000 ml/min/cm2)and low strength than the woven ones. In the early years of development, it was a common practice to precoat the graft with human blood before implantation to prevent blood leakage. However, the 0 Woodhead Publishing Limited, 2010 329
development of a new technique has eliminated the need for precoating the prosthetic tube.The technique involves: 0
0
the immersion of the tube inwater; draining the excess water h m the inside surface;and coating the inner walls, making use of a suitable biommpatible elastomer.
The coating material is usually a copolyester based polymer. However collagen, albumin, chitosan and elastane derivatives are also used to coat the graft. Knitted prostheses require precoating to prevent excessive blood loss during implantation. Gelatin, collagen and albumin are used to seal knitted Dacron sraft pores. A heparin bonded Dacron graft (InterVascular Inc) exhibited slightly better patency rates, compared to the untreated graft. Similarly, heparin treated ePTFE grafts showed improved patency rates. Dacron grafts coated with protein (collagedalbumin) and antibiotics have recently been manufactured to reduce the blood loss and to prevent graft infection respectively. Carbon is used for coating to improve the thennogenic features of Dacron prostheses but the overall patency rates are not improved when compared with that of untreated grafts. However, a recent clinical trial demonstrated higher patency rates of carbon coated ePTFE grafts by 1 - 2 year than that of standard graftsTable 1:Commercial Vascular Grafts Manufacturer Bard Meadox Golaski Sorin Biomedica Rhone Poulenc Coates-Paton Intermedia CS GoreTex hPra Johnson & Johnson St Jude Medical Socol Genetics Lab Source: M Grigiom et al(2)
Material PET (Woven, Weft knit, Velour weft and warp knit) PET (Woven, Warp knit, Velour warp knit, Umbilical vein) PET (Weft knit, Velour weft knit) PET (Carbon coated woven and knitted double velour) PET (Velour warp knit) PET ePET ePET ePET, Bovine carotid Bovine carotid Bovine carotid Umbilical vein
Several modifications to the basic graft were attempted in the past to improve its functional propextiessuch as increased tissue ingrowth, enhanced graft permeability and increased surface electronegativity. In addition to PET, ePET and ePTFE, polyurethane (PU)fibres were also used to design and develop grafts. Vascugraft was the first PU based graft but the graft underwent deterioration in v i v a It is found that the PU is susceptible to oxidative degradation. Polyester based PU graft (Pulse Tec) was then used but again suffered fiom in vivo degradation. However, polycarbonate PU grafi (Corvita) showed better stability and lower degradation. Research work is underway to develop a new technology for the manufiacture of compliant hybrid vascular gratts by making use of two types of yarns which match 330 0 Woodhead Publishing Limited, 201 0
human arteries. Application of nanotechnology has recently been focused to develop cardiovascularbypass graft. Researchers are currently facing challenges into developing small diameter vascular grafts with high patency rates by using appropriate fibres, structures and technologies. Endothelialisationat grafl inuer surfaces is a very important key to achieve long-term patency and to prevent graft infection. It is expected that excellent vascular grafts with all the desirable attributes would be fabricated in the near future.
KNEEIMPLANTS It is known that knee is stabilised by four ligaments such as Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), Medial Collateral Ligament (MCL) and Lateral Collateral Ligament (LCL) of which the ACL is a very important stabiliser of the femur on the tibia and serves to prevent the tibia from rotating and sliding forward during jumping, running and other quick or sudden physical movements. It is the most fkquently injured ligament and can be tom at a force of 33 N per kg of body mass or 3.3 times body weight (Fig la). The risk of ACL injury for f a a l e athletes is 2 to 3 times more, because of weaker hamstrings, than their male counterpart. Synthetic fibres such as polyester and carbon have been used in replacing a torn ACL (Fig 1b). Roflex ligament is made of polyethylene terephthalate polyester and consists of multiple braided tubes. Gore-Tex is a knitted cable with eyelets on each end. Polyurethane urea elastomeric fibres are also used for ACL reconstruction. The fibres possess high strength,high abrasion and tissue compatibility. The morphological behaviour and bone anchoring property of ACL made of polyethylene fibres have been studied. Carbon fibres have been incorporated in high-density polyethylene prostheses for total knee replacement. The requirements of an artificial ligament are extensive and it must have at least three important properties such as high tensile strength, high elongation and right stiffness to match the compliance of a normal ACL.
Fig 1a: Tom Anterior Cruciate Ligament (ACL)
Fig 1b: ACL Implant
MESH GWUTS Body organs can be repaired using mesh grafts. The grafts are made fiom the fabric of a net which contains an open texture and evenly spaced holes. The utilisation of mesh grafts in humans is based on the fact that, during the absorption period, a neomembrane 0 Woodhead Publishing Limited, 201 0 331
is formed in the site where the mesh has been implanted. Mesh graffs are also used to aid skinhealing. Some applicationsof mesh grafts on humans include: 0 0 0 0
treating a damaged kidney by external splinting or encapsulation;
repairing a damaged pelvic peritoneum; replacing membranes covering the brain, and repairing abdomkl wall defects (hernia).
scmoLDs Bioresorbable polymers such as polylactic acid (PLA), polyglycoloic acid (PGA), polydioxanone (PDS) and their copolymers are mostly used to make absorbable sutures, vascular grafts and scaffolds. Scaffolds a~ used to cultivate a number of human organs and body parts ranging h m skin, connective tissues, blood vessels, bones, heart and pancreas. The high-tech research involves the culturing and growing of living cells, taken fiom human organs, on a textile scaffold to the desired 2D andor 3D shapes. An extensive research has been carried out in the past to design and develop desirable scaffolds for the cultivation of specific organs by using different structures and fabric forming techniques. Electrospinning has recently been used to develop a 3D tubular scaffold using silk fibroin.
BIBLIOGRAPHY 1 A B Voorhees, A Jaretzki and A H Blackemore, Ann Surg, 1952 135 332. 2 M Grigiom, C Daniele, G B Avenio and V Barbam, Biomechanics and Hernodynamics of Graftmg: In M Rahman and M G Satish (Ed), Vascular Grafrs Experiment and Modelling, WIT Press, Southampton, UK, 2003. 3 A Mel, C Bolvin, M Edirisinghe, G Hamilton, A M Seifalian, ‘Development of Cardiovascular bypass grafts: endothelialisation and application of nan0te~h0l0gy’, Expert Review of Cardiovascular Theram, 2008 q9), 1259-1277. 4 J W Quarmby, K G Burmand, S J Lackhart et al, ‘Prospective randomised trial of
woven verses collagen impregnated knitted prosthetic dacron grafts in aortoiliac surgery’, Br JSurgery, 1998 85 775-777. 5 M Prager, P Polterauer, H J Bohmig et al, ‘Collagen verses gelatin-coated dacron verses stretch polytetrafluoroethylene in abdominal aortic bifurcation graft surgery: results of a seven-year prospective randomised multicentre trial‘, Surgery, 2001 130 408-414. 6 B H Walpoch, R Rogulenko, E Tikhvinskaia et al, ‘Improvement of patency rate in heparin-coated small synthetic vascular grafts,’ Circulation, 1998 98 11319-11323.
7 F M Groegler, X Kapfer, and W Meichelboech, ‘Does carbon improve PTFE bypass material?’, Proceedings of the 20* World Congress of the International Union of Angiology, April 7-1 1, New York, 2002.
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8 M G Jeschke, V Hermanutz, S E Wolf et al, ‘Polyurethane vascular prostheses decrease neointimal formation compared with expanding polytetrafluoroethylene’, J Vasc Surgery, 1999 29 168-176. 9 S Post, T Kraus, et al, ‘Dacron vs polytetrafluoroethylenegrafts for femoropopliteal bypass: A prospective randomised multicentre trial’, Eur J Vasc Endovasc Surg, 2001 22 226-23 1. 10 K GisselWt and P Flodin, ‘A biodegradable material for ACL reconstruction’, Macromol Symp, 1998 130 103-111. 11 K GisselfHt, P Flodin and B Edberg, ‘Biodegradable polyurethane fibres support natural h e a l i i processes’, Text Asia, 1998 29 52-54. 12 J M Pachence and J Kohn, ‘Biodegradable polymers’: In R P Lanza, R Langer, J Vacanti (Ed), Principals of Tissue Engineering, 2”dedition, Americal Press, San Diego, 2000. 13 S Rajendran and S C Anand, Developments in medical textiles, textile progress, P W Harrison (Ed), The Textile Institute, Manchester, 2002. 14 B Pairot de Fontenay, S Argaud and K Montell, ‘ACL injury: Female athlete case’, Jde TraumatoIogiedu Sporty2009 26(3) 155-162. 15 S Rajendran and S C Anand, ‘Medical textile devices for healthcare and medicine’, V.K.Kothari (Ed), Progress in Textiles: Science & Technology, 3 IAFL Publications, Delhi, 2008. 16 S L Edwards, S J Russell, E Ingham et al, ‘ Nonwoven scaffolds of improved design for the tissue engineering of the anterior cruciate ligament’, S C Anand, J F Kennedy, M Miraftab and S Rajendran (Eds), Medical Textiles and Biomaterials for Healthcare, Woodhead Publishing Limited, Cambridge, CRC Press LLC, Florida, 2006. 17 M Kun, C.Chan and S Ramakrishna, ‘Textile-based scaffolds for tissue engineering’, S.Rajendran (Ed), Advanced Textilesfor Wound Care, Woodhead Publishing Limited, Cambridge, CRC Press LLC, Florida, 2009.
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DESIGNING VENA CAVA FILTERS WFTH TEXTILE STRUCTURES J Yoon(’),M W King(’’) and E (1) College of Textiles, North Carolina State University,Raleigh, NC, USA (2) Hospital Saint-Frangois d’Assise, Universit6 Laval, Qu6bec, QC, Canada (3) Crux Biomedical Inc., Portola Valley, CA, USA ABSTRACT Pulmonary embolism is the tbird leading acute cardiovascular cause of death in the USA [l]. It has been reported that in the United States 355,000 patients are diagnosed annually with pulmonary embolism and over two thirds of the patients presenting with a pulmonary
embolism lead to death [2]. Although vena cava filters have been in clinical use since the 1960’s, they have not always been effective due to late complications This paper reviews the clinical performance of various styles and materials used in current vena cava filters, develops a list of design requirementsand describes a novel prototype textile construction that may serve as the next generation of devices. INTRODUCTION The vena cava is the largest win carrying blood back to the heart. Specificallythe inferior vena cava (IVC) is the vein below the heart returning blood f b m the abdomen and lower limbs, and the superior vena cava (SVC) is the path for blood returning from the brain, upper limbs, and heart (Figure 1). An embolism occurs when a blood clot or thrombus is formed and released in an inflamed vein, associated with pain and swelling, which is called deep vein thrombosis (DVT). The released clot, called an embolus, is carried by the bloodsteam and causes an obstruction in a downstream blood vessel or capillary. An embolus can be either part of a thrombus, or an air bubble, piece of fat, bone marrow, or tumor tissue [3]. Patients suffering h m arteriosclerosis, heart attacks, strokes, ce& blood disorders, and congestive cardiac disease, as well as those experiencing surgery or injury with bleeding are predisposed to embolus formation. In fact, when combined with other factors, such as obesity, sitting during long air flights, pregnancy, smoking, birth control medication, immobility and prolonged bed rest during serious illness, the incidence of deep vein thrombosis @VT) and embolism increases significantly [3]. In the event that a circulating clot enters the heart, it will circulate through the pulmonary artery to the lungs, where it will likely cause an obstruction in the capillary. Over time this may lead to pulmonary insufficiency, difficulty in breathing and chest pain, which are symptoms of pulmonary embolism (PE) (Figure 2).
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Right
anlecubRal vein
vena m a Right
rend vein
Right Iemoral vein
If 1
illiac
(I
vem
I
1 T
Figure 1: Venous system
Figure’ 2: Etiology of pulmonary embolism
The role of such filters is to trap large flocculent clots measuring greater than 5 mm in size before they arrive in the heart. The filter should hold such thrombi safely in the bloodstream to allow the natural process of clot lysis to be initiated by the plasma protein plasminogen and to permit slow dissolution of the clot over time. There are currently five alternativeapproaches for preventing andor treating pulmonary embolism. They are: i) post-operative mobilization of the patient with active and passive exercises; ii) thrombolytic therapy, in which, following blood studies, the patient is prescribed medication, such as warfarin or heparin, iii) anticoagulation therapy, in which the patient takes medication prophylactically, such as low dosage aspirin in order to prevent clot formation; iv) embolectomy, which involves a surgical intervention in order to remove a clot; and v) implantation of a permanent or retrievable filkx in the inferior vena cava. This fifth prophylactic approach is becoming increasingly popular for the 23-62% of patients at risk of DVT and for whom drug therapy is contraindicated[4].
CURRENT FILTERS FOR EMBOLIC PROTECTION
Filter insertion and deployment The standard site for the placement of vena cava filters is below the renal veins in the inferior vena cava. However, due to sizing limitations or when there is a high risk of releasing emboli from the kidneys, vena cava filters can also be placedin the suprarenal position (4.7%) (Figure 1)[4]. There are three approaches for the percutaneous insertion and delivery, and the specific recommended protocol depends on the specific device and entry site. Generally, noBinvasive access through a femoral vein is most fresuently used (82%), but alternatively,jugular, subclavian and antecubital approaches have also been found to be clinically successful (Figure 1) [4]. Delivery of an inferior vena cava filter requires the filter structure to be collapsedand loaded into a sheath that fits inside a 6 9 French (2-3 mm diameter) size catheter. A guidewire is first inserted into the vein and its position tracked by radiological imaging.
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Then the guidewire is used to insert the loaded catheter and position ttE sheath appropriately prior to deployment of the filter by Rleasing it fiom the sheath. One of the design requirements for the filter is that,once released, it should expand and push against the internal vessel wall. This ensures that it fits the vessel and generates sufficient radial force so as to prevent migration once implanted. Some degree of ovewizing is obviously a key factor in ensuring stable deployment and good fixation within the vessel, particularly as the vena cava is the most elastic and compliantvein in the body. Types of embolic protectionilltern
There are three main types of filters used for embolic protection. They are the permanent, retrievable and temporary filters. In the past, the use of permanent filters was considered the best therapy for patients with DVT. However, with increasing experience of late complications, surgeons are seeing merit in moving towards retrievable devices that can be withdrawn when the risk of PE has been l o w e d by drug or other treatments afta a period of 2-8 weeks. Temporary filters are designed for deployment and use during certain surgeries and interventions, such as angioplasty and hmbectomy that last for only a few hours. For this reason they remain tethered to their guidewires throqhout deployment. Because of the need for large multi-centred randomized clinical trials to determine their safety, efficacy and optimal usage, only seven permanent commercial filters and four retrievable filters have received approval h m the Food and L h g Administration for clinical use in the USA [3, 10, 111. A number of temporary filters are still under development [S] . Materials selection
At this time all commercial vena cava filters are fabricated h m either nitinol (nickel, cobalt, and titanium alloy), phynox (nickel, cobalt, chromium, iron, and molybdenum alloy), or stainless steel wire in various catheter sheath sizes ranging h m 714 French (2.3 4.7 mm diameter). These metals were chosen because they are biostable and have low thrombogenicity. This means that blood is less likely to form clots on the surface, and cells are not encouraged to grow around the device. Moreover, nitinol is a thermal shape memory alloy that is self-expanding after deployment and exposed to body temperature[11.
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Permanent filters All commercial IVC filters have evolved with a similar overall conical shaped design. Of the seven different permanent flters currently available in the United States, their styles have evolved into three types: conical, basket a d multilayered (Figure 3)[2]. With respect to their filtering ability against emboli, the basket and multilayered designs are considered more efficient than the conical design [6]. Even though permanent filters function relatively well,they have long-term complicationsas discussedbelow.
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Figure 3. Permanent vena cava filters (left to right): Simon nitinol filter (Bard), Over-thewire stainless steel Greenfield filter (Boston Scientific), TrapEase filter (Cordis Endovascular),and Bird’s nest filter (Cook)
Retrimble filters Retrievable filters can avoid some long-term complications because they can be retrieved from the body when they are no longer needed. However, they are usually retrieved within a relatively short term of 4-6 weeks. So sometimes the implantation time is too short to solve the clinical problem such as DVT. The design of retrievable filters is similar to that of permanent filters (Figure 4). One significant difference is that temporary filters have hooks at either one or both ends so that the filter can be retrieved by a wire when the filter is no longer needed.
Figure 4. Retrievable vena cava filters (left to right) Gunther tulip filter (Cook), Gunther tulip filter (Cook), Recovery filter (Bard), 0p-e filter (Cordis Endovascular) Temporary filtera
The role of a temporary filter is different from that of a permanent or retrievable device. Its purpose is to collect thrombi and debris that might be released into the blood stream during angioplasty and thrombectomy interventions. It is, therefore, attached to the tethering catheter while inside the body. Temporary filters are generally inserted into the jugular or femoral veins. Because of their short term use, temporary filters do not have barbs that
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might penetrate the wall of the vena cava (Figure 5). However, for this very reason, temporary filters have a greater chance to migrate, and, under certain circumstancesadverse incident reports of filter migration into the heart have been reported [7]. Currently no temporary filters have received FDA approval.
Figure 5. Temporary vena cava filters (left to right) Tempofilter I1 (EL Braun), Gunther filter (Cook), Neuhaus protect lilter (Toray), Antheor filter (Boston Scientific) Complicationswith current vma cava filters
Although vena cava filters have been in clinical use since the 1%O’s, they have not always been safe and effective due to late complications. A number of complications have been reported in the literature, including: recurrent pulmonary embolism (2-5%), inferior vena cava thrombosis (630%), access site thrombosis (2-28%), filter migration (349%), tilting (15-20Y0) (Figure 6), penetration of the vena cava wall (924%), structural fracture of the filter (1%), and guidewire entrapment (4% (Figure ) 7) [9].
Figure 6. Radiographic image of N C filter Figure 7. Radiographic image showing N C deployed with tilted orientation. Filter Eleased h m sheath, but entangled in guidewire.
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The high percentage of complications and adverse incidents demonstrates a range of limitations for IVC filters. The fkquencies are influenced by many factors, such as style of filter, design, material, site of deployment, access approach, patient anatomy, pathology and disease state. Clearly with such a high and unsatisfactory level of complications, there is a need for a more versatile, functional and durable device.
DISCUSSION ‘Ideal” inferior vena cava filter b i g n As can be seen in Figures 3,4 and 5 and fiom the reporb of clinical complications, the use of wire structures as IVC filters has a wide variability and lack of consistency in their clot trapping efficiency, their ability to be selfcentring, and their tendency to experience migration and thrombosis. It would, therefore, be u s e l l as part of the process of new product design and development to identify, prioritize and attempt to quantify the desirable features and characteristics of the “ideal” IVC filter design. To this end, we offer the following list of ten requirements. They are in no particular order.
Non-thrombogenic High filtration efficiency for emboli measuring at least 5 mm No impedance of flow and minimal turbulence Low thrombosis at access site Ease of insertion and retrieval Secure fixaton within the vena cava Minimal damage to luminal wall of vena cava No perforation of vena cava wall MR imaging compatibility (81 Low cost What the specific design inputs are for the various requirements, and how you measure them quantitatively to ensure validation of prototype candidates, is still under development. However, we offer the following prototype design with its unique textile structure as a potential idea for the next generation of IVC filters (Figure 8). The proposed filter consists of a nitinol wire, which is formed into a figure of eight. One of the lobes of the figure of eight contains an open mesh of PTFE yarns with known pore size openings, which provide a consistent clot trapping performance. The wire and mesh are fine and flexible enough to allow the device to be easily loaded, deployed and retrieved into and &om a 6 French (2 mm diameter) sheath. This gives the device a low profile, and, given that it is available in two sizes (S = 17-21 mm ID,L = 22-28 mm ID), this permits its use with a wide range of patient anatomies, including the jugular and femoral positions.
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Figure 8. Proposed new prototype WC filter based on a textile construction The simplicity of the design ensures that once deployed, it is self-centering. And,as long as the selection of the size deployed is greater than the diameter of the vena cava, then the likelihood of migration is minimized by the incorporationof small tissue anchors. In addition to having radio-opaquefeatures that ens- it can be readily visualized by radiography,the device contains a retrieval hook or tail to facilitate retrieval when used as a retrievable filter. Animaltrials are continuing to assess the ease of deployment and retrieval after 1 - 10 weeks in vivo. CONCLUSION Until now IVC filters have relied on conical and other shaped wire forms to serve as blood filters to prevent pulmonary embolism. The designs, styles and materials that are in commercial use lead to unacceptablelevels of late complications. We have therefore, proposed an alternative design approach using a flexible textile filter for the next generation of devices, which we believe will prove more clinically safe and efficaciousthan current commercial designs. REFERENCES
1 G Siskin, ‘Inferior vena cava filters’, eMedkine@,2005, h t t p : / l ~ ~ e s . g o o g l e . c o . k r / i m g r e s ? ~ ~ l ~ ~ : l l ~ . e m e d i c ~ . c o ~165~diof~age~7 7616IVC-Filter_Greenfield-2.jpg, May 16,2007. 2 .A Chiou et al., ‘Vena cava filters: why, when, what, how?’, Vasc Surg Endovarc Ther, 2005 17,329-339.
3 L Rosenblum,Pulmonary Embolism, MassachusettsGeneral Hospital Vascular Center, 2006; www.massgeneral.org/vascularcenterlpage.asp?id=pulmonaryembolism,March 28, 2007.
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4 C Athanasulis et al., ‘Inferior vena caval filters: review of a 26year singlecenter clinical experience’, Radiology,2000 216,5466. 5 ‘Vena cava filter device update’, Endovascular To*,
January 2005,68-69
6 H b r c h et al., ‘Efficacy ofpermanent and retrievable vena cava filters: Experimental studies and evaluation of a new device’, Cardiovaw Intervent Radiol, 2002 25,193-199.
7 G Bovyn et al., ‘Longdurationtemporary vena cava filter: A prospective 1W multicenter study’, J Vasc Surg, 2006 43,1222-1229,
e
8 B Matthews et al., ‘Inferiorvena cava filter placement: binsettion inferior vena cava imaging’, Z?zeAnnual Meeting Southeastern Surgical Congress, Savannah, Georgia, 2003.
9 T Kinney, ‘Update on inferior vena cava filters’,J Vasc Interv Radiol, 2003 14, (4) 425440.
10 D Imberti, ‘Retrievablevena cava filters: a review’, Current Opinion in Hematology, 2006 13,351-356. 11 H Lorch et al., ‘Currentpractice of temporary vena cava filter insertion: A multicenter registry’, JVIR, 2000 11,83-88.
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APPLICATION OF POLYWNYLIDENE FLUORIDE (PVDF)ASA BIOMATERIAL IN MEDICAL TEXTILES S. Houis', E. M. Engelhard?, F. Wurm2, T. Griesl 'Jnstitut ftir Textiltechnik, RWTH Aachenuniversity (RWTH-ITA), ilfschornsteinstraae 18,52062 Aachen, Germany Laboratory of Cellular Biotechnology, Ecole Polytechnique Fedbale de Lausme, Faculty of Life Sciences EPFL-SV-IBI, Station 6,1015 Lausme, Switzerland
ABSTRACT Textile implants so called scaf€olds are used for the reinforcement of tissue on the one
hand, and cell guidance on the other hand with the goal to support regeneration of new tissue. Different factors strongly influence cell ingrowth of the scaffold, namely the fibre material, the fibre structure and the textile structure. Depending on the final application of a textile scaffold, warp knitting, weaving, braiding and non-woven technologies can be used to manufktwe the textile structure. Thermal treatment can be applied to adjust the porosity, geometry and elasticity of the produced textiles. At the Institut Alr Texiltechnik at RWTH Aachen University (RWTH-ITA) polyvinylidene fluoride (PVDF) is used as a non-degradable and biocompatible polymer. PVDF shows very good biocompatibility and even bioneutrality. For the application in medical products, the PVDF is spun by a melt spinning process. In addition to multi- and monofilament also bicomponent fibres can be produced. Mdtifilaments are subject of currently carried out studies at the ITA. These multifilaments are used for medical applicationslike vascular grafts, ligament and artificial cornea. The artificial cornea is presented in detail. In another study, s d o l d s made out of PVDF fibres with varying diameter and cross section are produced. The influence of the miscellaneous scaffolds on cell adhesion is then investigated.
INTRODUCTION RWTH-ITA is working on the development of new applications of non- and degradable materials for medical textiles with focus on textile implants. Therefore all textile techniques from fibre spinning to manufacturing of implants in cooperation with partner institutes are used. The strength, flexibility and porosity of textiles make them especially suitable for medical implants. Textiles are usually used as supporting substrates for cells. Hence, a textile implant must be able to withstand continuously changing tensile, compression and bending stresses. Elastic elongation should correspond to that of the connective tissue being replaced, with rather higher strength. Textile structures play a major role in tissue regeneration and especially in tissue replacement, where they are usually used as supporting substrates for cells [PLA-89, "-01, m - 0 0 1 . Within the scope of several interdisciplinary research groups and in close cooperation with the University Hospital of RWTH Aachen University (Universitiitslchkm Aachen), special practice orientated implants and medical devices are developed with Merent materials. As an example for textiles in medicine, projects using PVDF as scaffold for tissue engineeringas well as for implants are explained further. 342 0 Woodhead Publishing Limited, 2010
STATE OF THE ART
Polymer Every implant evocates a reaction at the amptors tissue. This reaction mainly occurs at the interface of the implant and the tissue. A suitable biocompatiblepolymer is essential to reduce these reactions. The non degradable polymer currently in use for long-term textile implants and supports at the RWTH-ITA is PVDF (Polyvhylidene fluoride, -(CH2CF&). PVDF is a thexmoplastic fluoropolymer with excellent engineering properties and has found many uses in industrial applications as an established polymer. Properties include interesting ferroelectric behavior of piezo- and pyro-electricity, excellent biocompatibility and chemical resistance. The surface tension of PVDF can allow easy cleaning surfaces. The polymer is odourless, unsavoury and non toxic. It is already being used as medical sutures and hernia meshes, where it also exhibits improved elasticity and strength over polyester and polypropylene, two other polymers used for these applications. Additionally PVDF has potential in implant engineering as ligaments, vascular grafts or artificial cornea, PVDF is well known for its polymorphism, with at least four phases found experimentally. The different phases of PVDF can be characterized by the conformations of the -CHr and - C F r in the polymer chain. The main phases are the all-trans p-phase, TGTG’ a-phase and T3GT3G’ 7-phase [Du-O7]. These phases exhibit different properties which are also reflected in their surface properties. It was shown that the phases have an influence on surface roughness and also surface energy [JEE071. While there has been a lot of research in the crystalline structures of PVDF and in understanding the origination of its ferroelectric behavior, most of this research has been limited to the polymer as a film. Several studies show that the surface properties of materials influence cell growth. These studies mainly target on studying flat surfaces like foils. Influencing parameters are grooves IBR4-951, [CUR-97] surface roughness m - 0 2 1 or surface tension [JEN071. Very little is known about the influence of fibre structure on cell growth, but similar results as for flat surfaces can be expected. First investigations revealed an influence of fibre diameter on the growthrate of cells [JEN-OITJ, [JWAN-97]. Taking these factors into consideration, PVDF multifiiament fibres with varying diameter and cross sections with different morphologies were produced and the cellular response on these fibres was studied. Fibre development In textiles PVDF is used in form of monofilaments, hollow fibres and meltblown nonwovens. In architecture coatings of PVDF are applied to technical textiles of polyester or nylon. Recently results of electro spun PVDF have been published [And-081. Polisilk SA, Manresa, Spain, is the only known producer of multifilaments, but having only one fineness (500 denier, 42 filaments and 1000 denier, 84 filaments). At RWTH-ITA yams with tiner filaments and different cross section have been spun. Successll product development for medical purpose as well as promising properties and results were the motivation to intensify research on PVDF multifilament yams.
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PRODUCTION OF MEDICAL TEXTILES Spinning and characterization of PVDF multifilaments
The polymer material used for the artificial cornea was Solef 1008/0001and for the cell tests 1006/0001 produced by Solvay-Solexis S.A., Tavaux, France. The melt spinning trials were performed at a bicomponent plant (Fournk Polymertechnik GbmH, AlfterImpeh[oven, Germany, Figure 1). IP
Y
‘I‘ I
c. i8
7
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-Sl
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1 Sheat extruder 2 Core extruder 3 spinpumps 4 Spinneret 5 Monomer suction 6 Quenching chamber 7 Air supply 8 Spin finish application 9 Godet 1 10 Drawing area 1 11 Godet2 12 Drawing area 2 13 Godet 3 14Winder.
Figure 1: Scheme of bicomponent plant (left) and bicomponent plant (right) Round-, trilobal-, hollow- and snowflake shaped PVDF (Solef 1006) multifilaments were produced (Figure 2) mOU-O7].
Figure 2: Hollow (A) and trilobal (€3) shaped PVDF mulitfilaments The fibre morphology was investigated by Wide Angle X-Ray Difhction (WAXD) and Raman spectroscopy. WAXD was performed at the labs of Solvay Solexis S.p.A., Bollate, Italy. The X-Ray difhctometer used was X’Pert PRO MPD (PANdytical B.V., Almelo, Netherlands). The Raman spectra were obtained at the Institute fiir Physikalische Chemie der Universitlit Jena (PC), Jena, Germany with a micro-Raman setup (HR LabRam invers, HORIBA Jobin Yvon Inc, Bensheim, Germany). The spectrometer has an entrance slit of 100 pm and a focal length of 800 mm and is
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equipped with a 600-linedmm grating. As excitation wavelengths, the 532-nmline of a hquency-doubled Nd:YAG laser (Coherent Compass, Coherent Deutschland GmbH, Dieburg, Germany) with a laser power of 10 mW incident on the sample were used. The Raman-scattered light was detected by a charge-coupleddevice camera operating at 220 K. A Leica PLFluoar lOOx objective focused the laser light onto the samples (ca. 0.7 pm focus diameter). Integration time was 10 s, accumulation was 5.
Textile production Textiles have different properties, depending on their structure. For the following studies warp knitted structures were produced. Warp knitted structures are used if high elastic deformation is required. This type of mechanical property must be applied for implants that will be used for the reinforcement of an organ, subjected to continuously dynamic stress. [WUL-O6] Production of flat fabrics and branched tubular structures with various geometries can be produced at the RWTH-ITA with the help of a special double-needle-barRaschel Machine (Figure 3, Type DR 16 EECEAC Karl Mayer TextilmaschinenfaW GmbH, Oberhausen, Germany), Fields of application are e.g. keratoprosthesis (artificial cornea), vascular grafts, heart-valves, hernia-meshes and stents. The produced warp knitted fabrics can be set up concerning elongation and porosity and show a higher extension than woven fabrics. In contrast to knitted fabrics, warp knitted textile structures are insensible to cuttings, which means if a mesh is ripped up, the failure does not continue in the textile structure (a so called ladder). This property leads to high seam chunking resistance, which is especially needed for medical applications.
1
Figure 3: Double raschel warp-knittingmachine (left) and needle unit (right) For the investigation of PVDF-fibre influence on cell growth all PVDF yams were processed the same way to achieve a similar pore area and diameter.
Cell seeding Cell seeding was carried out at the Laboratory of Cellular Biotechnology, Ecole Polytechnique FCdirale de Lausanne, Lausanne, Switzerland. Several sterilized scaffold discs were added to a CultiFlask 50 tube (Sartorius AG, Gtittingen, Germany) containing a 10 ml culture of CHO-GFP4 cells at 0.3010~cells/ml (culture A) in ProCHO5 medium (Lonza Verviers SPRL,,Verviers, Belgium) supplemented with 0.5% 0 Woodhead Publishing Limited, 201 0 345
fetal calf serum. CHO-GFT4 is a stable cell line expressing the green fluorescent protein (GFP). After 4 h of incubation (seeding phase) Scaffold discs in each tube were transferred to a new CultiFlask 50 tube with 10 ml of fresh medium (culture B). Scaffolds from cultures A and B were used to measure cell attachment and growth of attached cells, respectively. At various time points, one &old disc and 1 ml of culture medium were removed fiom each CultiFlask 50. The culture medium was transferred into a 12-well plate and centrifuged for 5 min at 1500 rpm. The Supernatant was discarded and the cells in each well were lysed by addition of 1 ml lysis buffer (1% Triton X-100 in PBS). Scaffold discs were transferred to a 12-well-plak, washed once in PBS, and the attached cells d of lysis buffer. Mer 1 h of incubation at 37°C with were lysed by addition of I agitation, 200 pl cell lysate was transferred to a 96-well plate and the GFP-specific fluorescence was measured using a Safire2 Microplate Reader (excitation wavelength: 485 nm, emission wavelength: 515 nm) (Tecan AG, M&medorf, Switzerland). A standard curve of GFP-specific fluorescence versus cell number was generated with CHO-GFP4 cells grown in suspension culture as described above. Statistical analysis of the data was performed using the software R2.7.1. The significant differences between data sets was determined by ANOVA and Tukey multiple comparisons of means (95% family-wiseconfidence level). P-values smaller than 0.05 were considered as significant with the following nuances: p < 0.05 *, p < 0.01 ** and p < 0.001 ***
PROJECTS USING PVDF FOR MEDICAL APPLICATIONS In the following two projects involving PVDF as material for medical application are presented. These projects are in different stage of development. The first project is the development of an artificial cornea (keratoprosthesis). This prosthesis was already in clinical trial and stated its functionality and therefore is ready to be launched. The second project is a basic study in early stage. Here the aim is a fundamental understanding of the influence of different PVDF fibre structures on cell adhesion.
KeratoprosthesiS Production A large field of textile structures for medical applications is covered by the warp knitting technology, in particular the Double Raschel Warp Knitting Process. Using two parallel arranged needle-beds and at least two needle-bars, two flat warp knitted structures or a seamless three dimensional warp knitted structure can be produced. For the production of the keratoprosthesis(Figure 4) a single tricot bonding was used for the front fabric and a double tricot bondiig for the back fabric. The hole for the silicon cornea was inserted with pattern needle-bars, also connecting the two fabrics. The lens out of silicon is directly casted into the textile structure.
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Figure 4: Artificial cornea made h m PVDF fibres
Clinical trial Generally implants have to show a good biocompatibility, which means the toleration of the textile component for the field of medical textiles. The best biocompatibility is reached when the material resembles the replaced tissue. Quantitative analysis of cell growth on the artificial cornea show very good results (see Figure 5). The keratoprosthesis does not show any foreign body reactions.
Figure 5 : Seeding analysis on PVDF
Figure 6: Implantation of keratoprosthesis in human eye, some: ACTO
The keratoprosthesis is already implanted in two patients (see Figure 6 and Figure 7). Due to severe retinal trauma the eyesight was not recovered for the first patient after the implantation. The implant itself is clear and also perfectly adapted. In contrast the eyesight of the second patient was saved. Five days after operation the patients visual acuity raised from light perception to +6 dptr: 1/20 and color perception. The last meeting with the patient 3 months after implantation showed reading vision with a visual acuity of 0,16. Further testing will be carried out in the near future [HOU-O6], [LAN-001, [KOM-001,&OM-0 11.
Figure 7: Implanted keratoprosthesis in human eye, source: ACTO
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Influence of PVDF fibre propertiw on cell growth and adheaion Different PVDF fibres (round and snowflake shaped) were obtained with parameters listed in Table 1. These fibres Wered in filament number, draw ratio and draw temperature. The name indicates filament number, drawing POY: not drawn, FDY: draw ratio 2,5) and draw temperature (temperature given, FDY without temperature indication is drawn at standard temperature of 70 "C). These fibres are discussed in the following. Table 1:Produced PVDF fibres and their properties
Analysis of x-ray diffraction results (Figure 8) showed that there is only P-phase in the samples f17 FDY, fJ4 FDY, f72 FDY 70 "C and f72 FDY 160 OC.A mixture of aand P-phase was found for the sample Snowflake FDY and pure a-phase for f72 POY and Snowflake POY. The same trends were also confirmed by Raman spectroscopy. This is consistent with expected results from literature on phase transformations of PVDF. The samples only containing p-phase were all drawn to a maximum of 250 % at a temperature of 70 OC or higher. By drawing and applying heat to PVDF fibres a transformation of a- to p-phase takes place. In the present fibres this resulted in complete transformation fiom a to 0. Sample Snowflake FDY was drawn to a lower extend (200%) which results only in a partial a to p transformation(Figure 8, A). 900 Y
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20 25 30 10 15 20 25 30 Position [26] Position [26] Figure 8: WAXD results for snowflake shaped PVDF multitilaments (A) and PVDF filaments containing 72 filaments (€3) with indications of the a and p phases And finally the samples containing only a-phase were not drawn at all. From literature it is known that PVDF crystallizes in the a-form when cooled fiom the melt without processing of the material. In Figure 8 B the WAXD results for the 72 filaments are presented, in Figure 9 the results fiom the Raman spectra.The peaks indicatingthe a and p phases are labled. It could be shown that the formation of different crystal phases is possible with inline drawing of PVDF multifilament yams. 10
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Influence offibre structure on cell growth Since it is known that physical and structural properties of scaffolds influence the cellular response, different PVDF scaffolds were seeded with CHO-GFP4 cells (Figure 10, B) and cell attachment and growth were monitored as described above PNG-081. One trend was observed comparing the drawn PVDF multifilaments with different filament numbers. In Figure 10 A the results of cell attachment onto PVDF fibres after 4 hours are shown. Significant differences in cell attachment were observed between the fibres f17 FDY (diameter 28 pm) and D4 FDY (diameter 20 pm) as well as between f17 FDY and f72 FDY 7OoC (diameter 13 pm). CHO-GFP4 cells attached better on PVDF fibres with a finer single filament diameter. A significant difference between 34 and 72 filaments was not observed. To conclude, filament diameter of 20 pm and smaller as well as pore areas associated with this diameter seemed to enhance cell attachment.
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f17 FDYf34 FDY f12 FDY 70°C Figure 10: Comparison of cell attachment on PVDF fibres with different filament numbers and therefore diameter (A) and attached CHO-GFP4 cells on PVDF fibre (B) Another trend can be seen in Figure 11 where cell growth on different PVDF scaffolds all containing 72 filaments is represented. Cell growth is once expressed in 0 Woodhead Publishing Limited, 2010 349
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CONCLUSION PVDF is a suitable polymer for application in medical textiles. At the Institut fUr Textiltechnik RWTH Aachen University PVDF can be processed from polymer to the final medical textile. An artificial cornea (keratoprosthesis) out of PVDF was produced in close cooperation with the University Hospital of RWTH Aachen University (universitiltskhhm Aachen) and other Institutes. This prosthesis was tested and saved the eyesight of a patient. Basic studies in early stages are ongoing in order to understand the interaction of fibre structure and cell attachment using different PVDF fibres. Different PVDF multifilaments were spun. The spinning parameters resulted in m e r e n t crystalline structures. The main crystalline structures, a- and p-phase are achieved by varying the draw temperature and draw ratio. This is the first project to achieve different crystalline phases of PVDF in yarns through in-line drawing. Results showed that different textile properties had an influence on cell attachment and cell growth. Firstly, the fibre diameter influenced cell attachment. Finer fibres lead to better cell attachment. Secondly, drawn fibres supported a better cell growth than undrawn fibres with the same diameter. The obtained results suggest that an endproduct targeted fibre development leads to an improved implant performance. Specially designed fibres should therefore be considered in future implant development. Further investigation will be carried out using a different cell line to proof the achieved results. 350 0 Woodhead Publishing Limited, 2010
ACKNOWLEDGMENT Special thanks shall be expressed to the Stiflung Industrieforschung (Research foundation of the German industry) which founds the scholarship of the project “Development of new fibre structures for improvement of cell adhesion for medical textiles”. Further to Petra R6sch at the IPC for assistance in Raman spectroscopy and finally to Stefan0 Mortara and Mattia Bassi at Solvay Solexis for WAXD analysis.
REFERENCES
1 J S Andrew and D R Clarke, ‘Effect of electrospinning on the ferroelectric phase content of polyvinylidene difluoride fibers’, Langmuh 24 2008 670-672. 2 E T Den Braber, J E De Ruijter, H T J Smits, L A Ginsel, A F von Recum, J A Jansen, ‘Effect of parallel surface microgrooves and surface energy on cell growth’, J of Biomedical Materials Res, 1995 29 5 1 1-518. 3 A S G Curtis, C Wilkinson, ‘Topographical controls of cells’, Biomaterials, 1997 18 1573-1583. 4 C H D y B K Zhu, Y Y Xu, ‘Effects of stretching on crystalline phase structure and morphology of hard Elastic PVDF fibers’, JofAppl Polymer Sci, 2007 104 2254-2259.
5 E M Engelhardt, S Houis, T Gries, J Hilborn, M Adam, F M Wurm, ‘Suspensionadapted Chinese hamster ovary-derived cells expressing green fluorescent protein as a screening tool for biomaterials’, Biotechnology Letters, 2009 31(8) 1143-1 149.
6 S Houis, N Schrage, M Sri Harwoko, F Budillon, D Aibibu, T Gries, ‘Application of polyvinylidene fluoride (PVDF) as biomaterid in medical textiles’, In: Salonen, R (Hrsg.): Proceedings FiberMed 06 “Fibrous Products in Medical and Health Care”, Tampere/SF 07.-09.06.2006. - Tampere : Tampere University of Technology, 2006, paper: houisgaper.pdf. 7 S Houis, N Schedukat, T Gries, ‘PVDF: melt spinning of trilobal shaped, hollow fiber and fine multifilament yam’, Chemical Fibers International, 2007 51 122-123.
8 T Jee, H Lee, B Mika, H Liang, ‘Effect of microstructures of PVDF on surface adhesive forces’, Tribology Letters 2007 26 125-130. 9 M Jenkins, Biomedical Polymers, Cambridge, Woodhead Publishers, August 2007.
10 K Kaberer, ’Medical Textiles - the textiles inside us’, Medical textiles, Asian textile J0~mal9,2000153-54.
11 S Kompa, S Langefeld, B Kirchhof, K Brenman, N Schrage, ‘AachenKeratoprosthesis as temporary implant’, case report on first clinical application, Intl Jof Artificial Organs, 2000 23 345-348.
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12 S Kornpa, C Redbrake, S Langefeld, K Brenman, N Schrage, ‘The Type Il AachenKeratoprosthesis in humans case report of the iirst prolonged application’, Intl J of ArtijMaZ Organs 2001 24 110-114. 13 S Langefeld, S Kompa, C Redbrake, K Brenman, B Kirchhof, N F Schrage, Aachen keratoprosthesis as temporary implant for combined vitreoretiual surgery and keratoplasty: report on 10 clinical applications Graefe’s Archive for Clinical and Experimental Ophthalmology 2000 238 722-726. 14 N N, ‘10 Years of technical usage textiles’ : Medical ; In the medical area new products have been the object of regular articles, namely the hospital and medical textiles, vascular and ligament implants and grafts contention articles and bandages TUT 2 2001 40 37.
15 H Planck, M Darner, M Renardy, ‘Medical Textiles for Implantation’, Proceedings of the 3rd Intl ZZV Conf on Biomaterials, Stuttgart, June 14 - 16, 1989. - Berlin u.a Springer, 1990. 16 H Wan, R L Williams, P J Doherty, D F Williams, ‘A study of cell behaviour on the surfaces of multifilament materials’, J of Mat1 Sci: Materials in Medicine 1997 8 4551. 17 C D W Wilkinson, M Riehle, M Wood, J Gallagher, A S G Curtis, ‘The use of materials patterned on a nano- and micro-metric scale in cellular engineering’ Materials Science and Engineering, 2002 C 19 263-269. 18 B Wulfhorst, T Gries, D Veit, Textile Technology Munich : Hanser ; Cincinnati :
Hanser Gardner, 2006.
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TEXTILE SCAFFOLDS FOR TISSUE ENGINEERING- NEAR FUTUREOR JUST MSION? D. Aibibu; S. Houis; M. Sri Harwoko; Th.Gries Institut fur Textiltechnik der R W ,Aachen, Germany
ABSTRACT Scaffold production for tissue engineering with appropriate mechanical properties and architecture is currently attracting much attention. The development of textile scaffolds for tissue regeneration is of increasing importance, since these structures are very suitable for the substitution of human tissue and organs. Textiles have different properties, depending on their structure. Wq-knitted structures are used when high elastic deformation is required. This type of mechanical deformation must be concerned for implants that are designed for the reinforcement of an organ, subjected to continuously dynamic stress as for example vascular gtafts. Nonwovens have similar fibre structures to natural connective tissue and are well known and used in tissue engineering, because of their mazy structure and good water absorptivity. The design of innovative biomedical textile products is driven by various newly developed biocompatible, biodegradable and non degradable materials, such as Polygylocid acid (PGA), Polylactid acid (PLA) and Polyvinylidene floride (PVDF). These materials also necessitate an improvement of the established textile-processing procedures. PGA and PLA are biodegradable polymers and PVDF is non biodegradable. All have been used for preformed scaffolds production in tissue engineering applications because of their biocompatible characteristics. Therefore also the design of the scaffold structure has to be adjusted to the required tissue properties. Additionally to conventional scaffold production in one-step methods, textile structures can also be designed by combining different textiles (e.g. combination of warp-knitted and non-woven textile structures). The challenging part of the textile structuring is the setting of the machinery and the design of the textile structure.
INTRODUCTION Scaffold production for tissue engineering with appropriate mechanical properties and architecture is currently attracting much attention. The development of textile scaffolds for tissue regeneration is of increasing importance, since these structures are very suitable for the substitution of human tissue and organs. Textiles have different properties, depending on their structure. Warp knitted structures are used when high elastic deformation is required. This type of mechanical deformation must be concerned for implants that are designed for the reinforcement of an organ, subjected to continuously dynamic stress, for example vascular grafts. Nonwovens have similar fibre structures to natural connective tissue and are well known, and used in tissue engineering because of their mazy structure and good water absorptivity. Textile scaffolds have great advantages in comparison to other cell carriers as large volumes can be constructed with only a small amount of foreign tissue. Being a 3-D cell carrier structure, they can be adopted to the shape of the defect. Textiles are open porous, show a high specific surface and are drapable which allows an ideal adaptation 0 Woodhead Publishing Limited, 201 0 353
to the surrounding tissue. Further, their pore size, which is important for the nutrition of the cells, can be adjusted according to the demands of the replaced tissue and product. Since several years the Institute of Textile Technology in Aachen (ITA) develops, in close interdisciplinary cooperation with engineers, chemists, biologists and medical partners, production processes, products and testing methods in the field of medical textiles and biomaterials. The research group “Medical TextiledBiomakrials” at ITA follows the new Tissue Engineering approaches in two European Union h d e d projects, BioSys and 3GSCAFF. In the first project “BioSys (7ntelligent Biomaterial Systems for cardiovascular Tissue Repair)”, the RWTH Aachen University - Institut fiir Textiltechnik (RWTH ITA) cooperates with European partners with the common goal of developing a new intelligent biomaterial. This comprises two special performances, a controllable biodegradation and a good bioactive surface. For the evaluation of the new biomaterials, two textile scaffolds for cardiovascular tissue engineering, i.e. vascular grafts and heart valve implants will be tested in-vitro and in-vivo. The aim of the second project, “3G-SCAFF (Third Generation Scaffolds for Tissue Engineering t Regenerative Medicine)”, is to develop an extra-cellular matrix to be used as biomaterial. This matrix is a complex composition of essential materials where cells live and grow. The cells are used as a “micro factory” for the production and composition of a molecular structure - the extra cellular matrix - that cannot be produced with synthetic instruments.
MATERIALS The design of innovative biomedical textile products is driven by various newly developed biocompatible, biodegradable and non degradable materials, such as Polygylocid acid (PGA), Polylactid acid (PLA) and Polyvinylidene floride (PVDF). These materials also necessitate an improvement of the established textile-processing procedures. PGA and PLA are biodegradable polymers and PVDF is nonbiodegradable. All have been used for preformed scaffolds production in tissue engineering applications because of their biocompatible characteristics. Therefore, the design of the scaffold structure has to be adjusted to the required tissue properties. Methods
For the production of medical textiles ITA has a customdesigned warp knitting machine made by Karl Mayer Textilmaschinenfabrik GmbH, ObertshadGermany. Using different fibre materials and finenesses, a variety of two-dimensional and hollow struchms with branches can be designed and produced. The two different finenesses El8 and E30 allow the design of a wide range of surface structures and components. The warp knitting machine is designed modular so that its set-up can be adjusted according to the specific product. This allows the design and production of warpknits with adjustable mechanical properties and porosities. After knit-deknit-texturising,the multiflaments are converted into staple fibres. With the MDTA 3 (Uster Technologies AG, Uster, Switzerland), the opening of the fibres and formation of webs with a strong fibre orientation follows. For the production of homogenous webs, a laboratory card was designed and builds at the ITA. To achieve webs without a main fibre orientation the aerodynamic web formation process can be used. To avoid contamination and an accelerated degradation of the polymers, no 354 0 Woodhead Publishing Limited, 2010
thermal, chemical or wet bonding techniques can be employed. For these reasons the needle felting technique is applied.
RESULTS
Warp knit structures are used if high elastic deformation is required. This type of mechanical property must be concerned for implant that will be used to for the reinforcement of an organ, subjected to continuously dynamic stress ( Fig.1). Fields of application are, e.g. meniscus scaffold, silicon keratoprosthesis and vascular grafts [l-31. The characteristic of warp knit solution is the flexibility in mechanical properties and in design. The diversity of warp knitting technology allows the design and manufacturing of 3D-structure in one production step. But, for a most appropriate exact product design requirement definition is always being needed. Nonwovens are textile structures with non-regular structure and surface, which enable a pre-orientated growth of cells later on structures (Fig. 2). Nonwovens have comparable fibre structures to natural connective tissue and are well-known in tissue engineering, because of their mazy structure and good water absorptivity [4-71. The characteristic on the nonwoven is due to un-exact consistence surface structure. Nonwovens have non-regular build-up.
Fig. 1. Warp knit strucbure
Fig. 2. Nonwoven
DISCUSSION The important property for designing tissue engineering scaffold is the defined porosity. The porosity must provide enough space for giving the cell a living room to grow and as small as possible that the scaffold still has the required stability. Finding the right balance between porosity and stability is the most challenging part on designing any new scaffold. A tool, which allows a possible pre-design of the new scaffold, can improve the selection of the suitable textile structure and accelerate the manufacturing of textile scaffold. At ITA a design tool is developing, which allows an approach to the systematically design for manufacturing textile scaffold with low degree of product definition. This approach shall avoid disorientation during the design process and reduce consequently the manufacturingduration. The second important point by designing a textile scaffold is the choice of the raw materials. Textile gives possibility for using different kind of polymer types in pure material or in composite. ITA groups the raw material for the textile scaffold according 0 Woodhead Publishing Limited, 2010 355
to the final application of the scaffold. Short-time scaffolds, which shall support in defined-time (weeks or months) mechanically, need a biodegradable material. The degradation process can be controlled through the chemical structwe, the fibre production process (fibre spinning), the fibre profile and finally the textile manufacturing technique. Additionally to conventional scaffold production in one-step methods, textile structures can also be designed by combining different textiles (e.g. combination of warp-knitted and non-woven textile structures). The challenging part of the textile structuring is the setting of the machinery and the design of the textile structure.
A C K ” T S We acknowledge the European Comission for funding the research projects, the BioSys “Intelligent Biomaterial Systems for Cardiovascular Tissue Repair” and the 3G-SCAFF “3rd Generation Scaffolds for Tissue Engineering and Regenerative Medicine” REFERENCES 1 J Schillings, ‘Neue Copolyesteramide Rlr die Anwendung als Biomaterial: Synthese, Charakterisierung, Degradation und Zytokompatibilitlit’, Dissertation an der RWTH Aachen, 2003
2 E Bemdt, M Geuer, B Wulfhorst, Dreidimensionale Textilstrukturen zur Herstellung von technischen Textilien - Stand 2000 (Three-dimensional textile structures for the production of technical textiles) Technische Textilien, 2001 44 270-283, @208-E217 (TechnicalTextiles 44 (2001) 3 E Berndt, B Wullhorst, Gewirkte Biomaterialstrukturen entwickeln und
herstellenKettenwirk-Praxis,S. 44-4635 (2001), H.2, 4 M Kellomfiki et al. ‘Knitted mesh plates for tissue engineering’, Sixth world biomaterials congress, May 15-20, 2000, Kamuela, Hawaii, USA, TranSaCtions Vol III 2000
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5 T Gries, R Ramakers, U Wiesemann, N Schedukat, Medizinische Stapelfasern Herstellung und Anwendung in Vliesen ilir Zellhtigerstrukhuen (Medical stapel fibres: manufacturing and application of non-wovens for tissue engineering) Technische Textilien, 2000 45 @128-E129), 200-201(Technical Textiles 45 (2002)
6 T Gries, R Ramakers, U Wiesemann, N Schedukat, Medizinische Stapelfasern Herstellung und Anwendung in Vliesen Rlr Zelltrtigerstrukturen DWI Reports, S. 509513,2002/125
7 U Wiesemann, N Gbtten, T Gries, R M Paz, D Klee, M. Mbller, B Schmidt-Rohlfhg, K Gavenis, Vliese fUr die Ziichtung von Gelenkknorpel: Herstellung und Ausrllstuog mit MikrosphtirenDW Reports Paper: P-HI .pdf, 2003/127 8 U Wiesemann, R M Paz, N Schedukat, C Doussin, T Gries, Vliese ftir ZellMgerstnrkturen: Herstellung und A d t u n g mit Mikrosphiben DWI Reports S. 526-529,2003426 356 0 Woodhead Publishing Limited, 201 0
VISIBLE INVISIBILITY: CONTAMINATIONAWARETEXTILE SURFACES A Toomey Royal College of Art, London, UK
ABSTRACT Invisible killers such as MRSA, Closiridium diBcile, E-coli etc, are prevalent within the hospital environment. Current statistics put the instances of Hospital Acquired Infection at 300,000 per year. With an increasing ageing population there will be an increasing reliance on and need for healthcare. Apart from the contradiction of spreading secondary infection within a curative environment, there is an added cost to the health service due to Hospital Acquired Infections. ‘The surfaces in a current hospital environment are all collectors and harbourers of these biohazards. There is no way of accurately knowing how clean the area is. Current hygiene practice aims to keep levels of contaminationbelow a dangerous level. There is suf€icient evidence to indicate that this is not effective enough. If you clean a floor with disinfectant you eradicate 95% of germs. If you simply wash a floor you eradicate 80% of germs. However, within 1 hour the levels of contamination will have reverted back to the original state whichever process you use. Biohazards such as MRSA are brought into the environment in the noses of and on the hands of patients, visitors and workers alike. Most humans harbour and pass on the vast majority of germs, but the vast majority of germs are not handid to most humans. It is the critical area of hand bourn contamination in an environment where there is an increased ‘at risk’ group due to illness and surgery that needs improved levels of hygiene. The immediate instances and levels of contamination are completely unknown.. .it is only known retrospectively after the infection has occurred and the data collected. Imagine instead an environment where the surfaces could not only alert you to the presence of infection but could even communicate the level of contamination and whether or not the environment had become dangerous. There is a need for a visual warning indicator, preferably within the immediate vicinity of contamination and that responds whilst in situ and is not reliant on off site lab tests. A textile-based substrate would have advantages of being washable, renewable and cost effective. The ‘Visible Invisibility’ project investigates contamination aware textile surfaces with applications within healthcare and aims to eventually develop printable ink that will change colour to indicate the presence of bacteria. Questions around the selectivity of the sensor, for instance what bugs does it react to, the sensitivity of the sensor, what levels of contamination need to be present to get a reaction, what is the speed of the reaction and is it reversible all need to be addressed and answered. Within the context of visual warning indicators the project will look at addressing the environment of the patient, identifying particularly harmful biohazards. The work will eventually address the wider possible applications that could have a much broader materials application. The focus of this project is to establish the basic principle that a selective ‘need to know’ visual warning indicator would be more effective in maintaining hygiene levels than is currently the case and that,if it is possible to develop a contamination aware textile surface, to produce proof of concept, possibly in garment or curtain form as a prototype for trials in a healthcare environment. 0 Woodhead Publishing Limited, 201 0 357
Precedents: Work investigating biosensors and colour changing warning indicators is currently being carried out. Two projects that have particular relevance are: Dr Margaret Frey,Cornell University,Ithaca, New York As published in the ‘Journal of Membrane Science’ 279 (2006) Dr Frey has successmy prepared nanofibre substrates for biosensors based on biotin-streptavidin specific binding. When it is eventually produced, testing a surface for biohazards such as E coli could be as simple as giving it a wipe. Dr Simon Aldridge, Cardiff School of Chemistry Developing colour changing toxic chemical sensors for air-bourn contamination with Military applications. Similar issues and challenges of selectivity, sensitivity and speed of reaction apply to these projects and the ‘Visible Invisibility” project alike. What does this give us and where can it lead us? Can we alter the way that we inhabit, utilise and respond to an environment by being given information about the dangers present within it? It is widely accepted that hand bourn contamination is a major contributor to the s p d of hospital infection. Alcohol based gels are already prolifically installed within the hospital environment and yet something as simple as cleaning your hands hquently enough, even though the benefits are known, is still evading the health sector. Is it a question of how the information is delivered? In an age of information overload would it be more effective to deliver targeted information as and only when it was needed? This project has the potential to reduce both levels and spread of infection to an increasing proportion of the population. A few of the many possible applicationsinclude: Curtains, bed covers to detect general cleanliness of environment Sheets specificallyalerted to bed sore warning Bandages to alert to wound contamination Uniforms of hospital staff.. .surgical, nursing and auxiliary
How people relate to, use and are reassured by their environment is paramount. By putting the human at the centre of focus it should be possible to make the hospital environment, including the textiles used within it, more user Mendly. Making the environment smarter and safer is a major contributorto this area. INTRODUCTION
Textiles have a benign identity in most peoples’ minds. It is our most intimate and immediate interface with the world we inhabit, becoming like a second skin. It shelters and protects and through the almost endless varieties of fibre composition, structure and colour gives us tremendous choice in how we use these properties. Textiles feature significantly in healthcare in a wide range of contexts from dressings, through bedding and patient gowns to hospital curtains, uniforms and sterile clothing. 358 0 Woodhead Publishing Limited, 2010
.The familiar and comfortable role of textiles is b e i i questioned by designers, manufacturers and users; the familiar is no longer quite what we think it is, although it still looks and feels the same, but through embedded technologies such as antimicrobial finishes, conductive prints and fibres and auxetic structures for drug delivery is quietly becoming increasingly more intelligent. The lo-tech humble cotton sheet can now be thought of as a dynamic surface that could potentially monitor, store and transmit information relating to your immediate state of health, deliver your drugs to you, protect you against bacterial contamination, and, as this paper proposes, it could also monitor and detect levels of contamination. Its very close proximity to the way we live offers an unprecedented opportunityto not only reduce delay times in dmgnostics, monitoring and drug delivery, but also to deliver a unique and personalised response in these aspects as the textile is next to the skin and can respond to individual needs. The opportunity for textiles to enhance patient safety, improve healthcare delivery and to improve treatment outcomes is very real. Consider the textiles within a healthcare environment in terms of the total surface area, not in terms of different product types and there is an immediate realisation of the potential for textiles in this context if the interface of the surface and the user is fully exploited, especially when combined with ‘smart’ technologies.
INFECTION RISKS
This paper considers one aspect of patient safety and examines the role of textiles in relation to infection control, in particular, what is known as ‘hospital-acquired infections’ or H.A.I.’s. Invisible killers such as Methicillin Resistant Staphylococcus aureus (MRSA) and other antibiotic resistant pathogens such as Clostridium difJici1e are a major cause of morbidity and mortality within hospitals worldwide. Current statistics put the instances of Hospital Acquired Infection at 300,000 per year’ incurring an added cost to the health service due to H.A.1.k. In 2000 the estimated cost to the NHS was as much as €1 billion2.With instances of HAI’s increasing (cases of C-Difficile rose by 17% in 2005) the need to prevent cross-infection and reduce environmental contamination in hospitals has never been greater. With MRSA, not only is this group of Staphylococci (about 6 strains) now always present within the hospital environment but is now also present within the community. This bug, and other antibiotic resistant strains are highly adaptive. For example, in 1959 the first synthetic penicillin, methycillin, was introduced. By 1961 there was the first case of h4RSA3. There are few new classes of antibiotics and little incentive for further research funded by the pharmaceutical industry due to the lower return on investment with this type of drug. Given the adaptability of this and other equally hazardous bacteria suggests that the reliance on current hygiene practice and antimicrobial h i s h e s presently being used to combat the problem of antibiotic resistant strains alone would be optimistic. The use of an on-site contaminationdetection system embedded into the surface of the textiles used a hospital alongside antimicrobial fabric treatments (bacteriostatic or bacteriocidal ‘methods) would alert the user to changes in the level of bacterial contamination they are in contact with as it happens.
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‘Mosthumans harbour and pass on the vast majority of germs, but the vast majority of germs are not harmful to most human^'^. For most of the population there is little or no risk. However, a significant proportion of patients in a hospital environment, particularly the elderly, are in a risk category due to lowered immune systems and surgery, and therefore the ‘not harmful to most humans’ balance alters. With an increasing ageing population requiring healthcare that will have multiple and complex conditions, and therefore in a high-risk category, the problem of HAI’s and how they are dealt with is going to become more fiequent and more acute. INFECTION CONTROL Many hospital environments are now acknowledged to have MRSA and other pathogenic strains always present. There are many viewpoints on how this has arisen and speculation and blame continues to grow. Some views are that it is down to the overuse of antibiotics, others that hospitals are not designed with the patient as centre but are structured around making life easier for the specialist medical staff to carry out their work. The occurrence of contamhation is inevitable, but how it is prevented, reduced or dealt with varies. Identification of the presence of MRSA and isolation of carriers together with complete in house laundering is one way to deal with the problem, as has been successfullyproven within the Dutch healthcare system. This method has not been adopted in the UK, along with many other countries, and so alternative strategies have to be used. Improved hand hygiene, including the use of alcohol gels, (effective against MRSA but not against C drflcile) can and have made a difference if used fkequently and appropriately. However, as a patient, there is no way of knowing how clean your “hospital environment is, nor are you able to influence the cleanliness of your environment. As a patient you have no control over your situation. You are either fortunate and stay clear of contact with pathogens or you are unfortunate and if in a risk category, become infected. ‘If you clean a floor with disinfectant you eradicate 95% of germs. If you simply wash a floor you eradicate 80% of germs. However, within 1 hour the levels of contamination will have reverted back to the original state whichever process you use.’ The level of bacterial contamination can alter and multiply rapidly and to confidently control and minimise potentially hazardous situations requires constant attention. Antimicrobial fabrics utilising silver, chitosan, titanium dioxide and antibacterial polymers are being developed, produced and improved. Performance tests show that they are effective but different types of antimicrobial fabrics can vary significantly on the level of bacteriostatic or bacteriocidal performance that each type delivers. However, long term effects of the antimicrobial should also be considered since there is a school of thought that suggests that certain agents may in the long term,particularly with the ‘St8tic’ class of agents, actually promote the growth of micro-organisms which develop resistance to the agents themselves6. Under present practice this will only become apparent when there is an increase in recorded instances of HAI’s.
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Contamination happens. Conventional lab methods can accurately detect micro organisms, but the tests take hours or even days to complete - far too long in many circumstances. The potential value of a detection system incorporated into the fabric will alert the user to danger before the contaminationreaches critical levels. Reducing that time to detection is a goal that a number of research groups are pursuing. Dr. Margaret Frey and Antje Baeumner of Cornell University have investigated biosensors and colour changing warning indicators. A nanofibre substrate has been successfully prepared for biosensors based on biotinstreptavidin specific binding7. This is a prototype detection system that shows promise of leading the way to future test kits that operate in less than ten minutes. The prototype was built using a blend of the two researchers’ areas of expertise: fibre technology and biosensor engineering. A coloured molecule provides the visual detection signal. After a washing step, any colour remaining gives a positive indication. The whole process takes just a few minutes to complete. When it is eventually produced, testing a surface for biohazards such as E. coli could be as simple as giving it a wipe’. The benefit of the nano-sized fibres creates a greater proportion of the material as surface, and as detection takes place on the surface a higher number of sensing sites can be incorporated9. Although the potential of this colour changing indicator is extremely promising in reducing the time to detection it still involves a time delay and also introduces an extra task in wiping the surface, plus a sequence of additional processes to reveal the presence of pathogens. Given the time pressure that hospital staff work under there is a need for a visual warning indicator that reduces the detection time, and tasks involved even further, or ideally to zero. The potential effectiveness of textiles in detecting and monitoring contamination could be dramatically increased by incorporating a colour changing sensor directly onto surfaces to capture and reveal the pathogens in contact with and surrounding the patient in one process without the need for off site lab tests. The ‘visible invisibility’ project aims to do this by creating a responsive surface, responding whilst in situ and not reliant on extra checks or off site lab tests. This could create an environment where the surfaces could not only alert you to the presence of pathogens but could even communicate the level of contamination and whether or not the wound, the bedclothes, the staff uniforms or the environment surrounding the patient were carrying dangerous levels of contamination. ‘VISIBLE INVISIBILITY’, CONTAMINATION AWARE SURFACES The ‘Visible Invisibility’ project investigates the possibility of creating contamination aware textile surfaces such as hospital ‘privacy’ curtains, bedclothes, nurses uniforms and wound dressings and aims to develop a printable ink that will change colour to indicate the presence of bacteria. Intended to react in a similar fashion to that of the home pregnancy test kit, although the reacting surface is in direct contact with the skin in the case in wound dressings or with the patients’ environment in the case of bedclothes, curtains and uniforms. The range of printable inks,both currently in use and being developed, such as themachromic and conductive inks as well as printed human cells for tissue repair suggest that this might not be unrealistic. ECI Biotech have
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developed a means of identifying the presence of bacteria and other pathogens by engineering assays that chan e colour in the presence of host specitic secretions for detection of wound infection’ . This project will examine aspects of the selectivity of the sensor, for instance what bugs does it react to,the sensitivity of the sensor, what levels of contamhation need to be present to get a reaction,what is the speed of the reaction and is it reversible in order to identify a suitable sensor that could be incorporated into an ink. The background levels of bacteria need to be recognised, both on human skin and in the environment. A sensor that is too broad spectrum would always result in a positive indication and therefore be of little or no use whatsoever. The immediacy of the interface between textiles and the patient offer potential to reduce delay in detection time to zero, or close to zero. Altering the relationship of the surface area of the fabric to contact with contamination, through working on a nano-scale may shift these levels of speed, sensitivity and selectivity. The work of Dr Margared Frey, as mentioned previously, has already demonstrated the relationship of an increased surface area with increased performancevalue. The value of a changing image over a static image that a colour changing ink would offer means that the printed surface delivers information or a response on a need to know basis, only when conditions have changed and pose a hazard...reducing the galvanizing effect of ever present warnings and reminders (as in the clean hands campaign). A textile substraie has advantages of washability, renewability and cost effectiveness but these benefits can only be fully employed if the sensor if reversible and not reduced through a washing process. C. dzJiciZe forms spores, which can survive for long periods on floors and round toilets, and a textile substrate for the sensor may not be appropriate. A non-reversible sensor could be used in the form of a disposable sticker placed onto high-risk surfaces. This could prove beneficial in identifying best practice in cleaning and laundering methods. The comfortable identity of textiles, especially in a hospital environment, is also relevant. The printed ink can be used in a highly visible, decorative and familiar way with selective use of imagery and pattern maintaining the benign and comfortable role of textiles whilst simultaneously incorporating hctionality and intelligence. The threshold between fear and comfort or health and safety needs to be considered when selecting one type of graphic over another for means of a warning indicator showing the presence of bacteria. Research will be conducted into this threshold to establish the most suitable graphic. A uniform printed with the colour changing pathogen sensitive ink that grows ‘wash me’ text as the bacteria spreads and grow across the fabric alerts both staff and patients to possible danger ‘see Fig. 1’. The same graphic printed onto a hospital gown may not inspire confidence or peace of mind in the patient waiting to go to theatre. Bedclothesor wound bandages printed with visible invisibility ink responding to the growth of infection by displaying hazard symbols as a warning indicator may be too alarming (Fig. 2 and 3). However, if the benefit to patient safety is evident it is possible for patients to accept unlikely applications, as in the use of a textile ‘bag’developed for containingthe maggots used to clean wounds.
f
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Fig. 2 Colour changing pathogen sensitive ink with hazard symbol graphic.
Fig. 3 Use of hazard symbol graphic on bandage.
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...... ......
1111~1
.........
.
Fig. 4 Colout changing pathogen sensitive ink with decorative floral graphic.
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Equally, a decorative floral with a subtle change in motif, or a stripe with an extra colour may be too passive for the purpose of a warning indicator (Fig. 4). The use of symbols or motifs over text offers opportunities to cross language and literacy barriers and therefore reach a wider audience providing the message conveyed is understandable.
CONCLUSION The important aims of this project are a reduction in both the task of testing, therefore saving time and labour, as the detection is done on site, and in reducing the time to detection thereby offering the possibility to intervene before infection reaches critical levels. It is a more inclusive model as it has potential to inform all users of the hospital, patients, staff and visitors, of the current hygiene status of their immediate and relevant surroundings. The informed patient has an active role in monitoring the hygiene status of their environment. This would transfer some of the burden of vigilance in hospital cleanliness away from staff. How people relate to, use and are reassured by their environment is paramount. By putting the patient at the centre of focus and exploiting the most potent surfaces surrounding the individual it should be possible to make the hospital environment safer by making it smarter. Antimicrobial finishes on equipment and fabrics and hygiene awareness through clean hands campaigns have a significant role in the reduction of HAI’s. However there is no one single ‘magic bullet’ that will eradicate or control hospital acquired infection but rather a combination of approachesworking together in a cohesive and constantly evolving way. The visible invisibility project does not negate these valuable contributions to the infection control in the healthcare environment but would complement these approaches and enhance the overall possibility of reducing HAI’s by improving awareness and detection of contamination.
REFERENCES 1 http://www.thesahara.net/clostsidium_dif
2 National Audit Office, The management and control of Hospital Acquired Infection in Acute NHS Trusts, 2006.
3 Mark C. Enright, Department of Infectious Disease Epidemiology, Imperial College, London, 2007.
4 Peter Hofhan. Clinical Scientist. Laboratory of Healthcare-associated Infection. Health Protection Agency.
5 Peter Hofsnan. Clinical Scientist. Laboratory of Healthcare associated Infection. Health Protection Agency. 6 Shirley Technologies Ltd, The Layman ’s guide to antimicrobialfabrics and testing methoak, England, 2004.
7 Li D, M W Frey and A J Baeumner, ‘Electrospun polylactic acid nanofibre membrane as substrates for biosensor assemblies’, JMembrane Science, 2006 279(1-2) 354-363. 366 0 Woodhead Publishing Limited, 201 0
8 Guardian newspaper, London 18/O9/06. 9 Margaret Frey, Cornell University, NY 2007, Private Communication. 10 http://www.ecibiotech.com/index.php?id-&ection
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TEXTILE MEDICAL PRODUC’IS FOR THE STABILIZATION OF THE THORACIC WALL E Alexandra and M Carmen The Research-DevelopmentNational Institute for Textile and Leather, Bucharest, Romania &
N Alexandru “Victor Babes” Medical and Pharmaceutical University, Timisoara, Romania ABSTRACT Stabilization of the thoracic wall together with the reconstruction of the soft parts represent the two essential components of the thoracic parietal reconstruction after a pariectomy. The purpose of assuring an efficient structural support of the thoracic wall consists in avoiding paradoxal breathing and pulmonar hernia The product is destined to be used in the case of the parietal faults no matter where they are localized ( stem, antero-lateral thoracic wall, posterior scapular thoracic wall etc.) and what is the size of the fault. The product which, by its geometrical, technical, biofunctional and biomedical characteristicshas to meet the imposed requirements, such as: -adaptability to any shape and size of the fault; -malleability;-durability in view of avoiding paradoxal breathing; -non reactivity at the fluids of human bodies; - resistance to infections; -radio transparency. The obtained product represents a great novelty, its innovative character being given by the whole conception of the article made in conformity with the exigencies specific to the destination, for which they are definite: the type of the used raw material, elaboration and projection of the textile support, establishment of the manufacturing technology so as to ensure the biological, microbiological, biofunctional and technical characteristics imposed by the actual norms for the products linked to human tissue for minimum 90 days. The paper present the product of Romanian conception which was used having remarkable results both for the parietal stabilization concerning some previous lateral faults, and also for the cases when there was a smaller fault ( resection of two ribs) for which it was considered as obligatory the assuring of the stabilization especially because of the patients age or the breathing function alteration as well as the correlation with the international evolution of these category of products, level of biomedical and biofunctional performances, admissibility condition imposed by the European laws in force regarding the fabrication and commercialization.
INTRODUCTION Stabilisation of the thoracic wall together with the reconstruction of the soft parts represent the two essential components of the thoracic parietal reconstruction after a pariectomy. The purpose of assuring an efficient structural support of the thoracic wall consists in avoiding paradoxal breathing and pulmonar hernia. At present, most of the thoracic surgeons (1) accept that a fault bigger than 5 cm necessitates stabilization, except for those faults situated on the posterior thorax, covered by scapula. For the last ten years there have been a lot of products destined to this field that deals with the assuring of the thoracic structural support after enlarged pariectomies by using a varied range of homologues, authologues or alloplastic materials. It is to be mentioned that in 368 0 Woodhead Publishing Limited, 2010
the specialized literature, extensive studies on thoracic parietal reconstruction on patients with obvious presurgical alteration of the breathing tests. Usually, breathing adaptability studies refer to those patients that went through normal presurgical ventilator tests. USA have highly experienced in the thoracic wall reconstruction, consider that the most adequate materials are Prolene mesh and Goretex soft tissue patch. The most used material is Marlene mesh (2), but once this material is under tension, becomes rigid, only in one direction. The American medical centers (3) are highly experienced in using a composite material (methyl methacrylate) but which is being rarely used at present, because of the intrasurgical preparation difficulty and exotherm reaction that causes pulmonar burns. New materials have been tested on a limited number of patients. These materials are represented by: Polyester mesh (Japan 1992), Polydioxanon band grid (USA), Polilactide (Japan 1994) processed sheep dermic collagen (USA 1991), expanded polytretraflouroethylene ( Germany 1992) .At present experiments with bioceramical materials are being made, but there is one disadvantage of intrasurgical modelling impossibility (4). Recently, it has been discovered that reconstruction of soft and semirigid tissues can be made by using some textile supports of polymers and copolymers with controlled reabsorption, during 90 days, at least, so that this phenomenon happens after the implant carried out its clinical function. The most important companies producing reasorbed biomaterials, with textile structures are: Johnson & Johnson- USA, ETHICON- France, Japan Medical Supply Co- Japan, Nippon Kayaku- Japan etc. Great results were obtained by using polymers whose absorption is due to hidrolithical degradation of glycol acid esters and also using copolymers with glycolic acid and lactic acid, or p l y ( N- acid- D- glucosamine). All these materials are hard to find and very expensive. The above technical, financial and functional inconveniences made the specialists from INCDTP to approach a research subject of an interdisciplinary character having as main objective the accomplishent of a product in order to meet the requirements imposed by the clinical utilization field. The product is destined to be used in the case of the parietal faults no matter where they are localised (stern, antero-lateral thoracic wall, posterior scapular thoracic wall etc.) and what is the size of the fault. The product which, by its geometrical, technical, biofunctional and biomedical characteristicshas to meet the imposed requirements, such as:
- adaptability to any shape and size of the fault;
- malleability; - durability in view of avoiding paradoxal breathing; - non reactivity at the fluids of human bodies;
- resistance to infections;
- radio transparency;and - does not dezintegrated and it can be incorporated in the host tissues. The clinical studies have to be performed in the following situations:
- bone malignant tumour ( primitive and secondary);
- malignant t u m o ~of r soft parts; a
d
- benignant tumow.
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EXPERIMENTAL Performances level imposed on the product has been achieved by approacbiug some new and complex technological elements such as:
- assimilationwithin the manufacturingtechnological processes of the textile knitted supports, of the synthetic fibers on the base of the biomedical polymers, characterized by resistand small weight ratio, controlled elasticity and flexibility; designing of the knitted fabric structuresand the appropriate correlation of the technological conditions of obtaining, by knitting, textile supports, in order to ensure the level of the biofunctional performances parameters, such as texture of outer surface compared to that of the human body, controlled compactness, thickness, porosity and permeability; elaboratinga new technologicalinserting solution within the structures of the textile knitted materids, a monofilament polyester yarn in order to ensure a dimensional stability of the product during the implant process; superior finishing of the implanting medical products, to ensure the physicochemical characteristics( lack of organically substances, oxide- reducing substances, aspect, smell, color) and biological ones ( lack of intacutaneous reactivity, toxicity on a flog's heart, sensitivenessat materials implant within tissues etc.) imposed by the international standards of the field for this category of products; ensuring of the microbiological characteristics of the finished products by the appropriate correlation of the sterilization parameters depending on the nature of the used raw materials; and maintenance of the level of the microbiological characteristics during storage and transportation by the achieving of a new type of welding (double flat band of the special package soft multilayered foil doubled by paper, according to the requirements imposed by the internationalnorms.
-
-
-
-
The surgical reinforced net, destined for the reconstruction of the thoracic wall, distinguishesby:
- used raw materials; - filament yams of 100% polyester of biomedical quality with a length density of 76 dtex f 32; - monofilaments of 100% polyester of biomedical q d t y with length density of 2250 dtex; - manufkturing technology; - knitting by means of KOKE'M' warp knitting machine; - structure- file; - knitting thickness - 23 stitches per cm 2; and - resistance to bursting- 4,1 kgf7 cm '. The use of the PES mono and multifilament yarns allowed the ensuring of the proper level of the physico-mechanical characteristics, resistance to the action of the chemical agents as part of the liquids, serums and human body blood, maintenance of the product biofimctional properties during implant process, thus contributing to the avoidance of new surgical operations with traumatic effects on human body and psychic. All these elements determined the achieving of a complex product with dimensional stability dominant coderred by the link type and the structure parameters as well as by using 370 0 Woodhead Publishing Limited, 2010
some raw materials proper to the chemical nature, structure and biocompatibility degree. CLINICAL EXPERIMENTS It is to be mentioned that the product has been developed and tested from the point of view of its behavior under clinical conditions (in vivo and in vitro) in collaboration with world-known doctors. Clinical testing was carried out in a period of 4 years, thus it can be appreciated that these tests are outstanding due to the great number of the products (variants and structures), being used in order to establish the optimum variant from the clinical point of view. The first determinationsof the clinical behavior were made on a lot of 20 products pieces, and the clinical cases were represented by:
-
malignant tumor of right fore thoracic wall - a C 1 and C3 thoracic pariectorny, clavicle parietal rejection and sternal manubriu were achieved; - secondary malignant tumor of right fore thoracic wall (secondary determination after breast cancer operation), ganulometrical chronically inflammation of fore thoracic wall with cutaneous fistula; - malignant tumor, ribs 1- 3 leR, clavicle and manubriu; - right malignant tumor with the infiltration of the thoracic wall and diaphragm; - for thoracic parietectomy for malignant tumor; and - huge stern tumor, total sternectomy.
RESULTS In all of these cases, the reinforced net was well tolerated, without any parietal running.
Fig1. Reinforced mesh in clinical usage Stabilization of the thoracic wall was very good, except for one case when it was necessary the association of two sustaining metal blades (total sternectomy) (Fig.1). In order to ensure the recovery of the soft parts one or two muscular grafts were added on the thoracic reinforced net. For the finishing of the clinical experimentsthere were used a lot of 20 products such as: 0 Woodhead
Publishing Limited, 2010 371
- diagnosis: fore right thoracic parietal tumor- the reconstructionof a reinforced parietal net was done; - diagnosis: lateral right thoracic parietal tumor; and - diagnosis: for thoracic parietal tumor, The conclusions of the preclinical and clinical studies showed the following advantages of the product:
-
strong support for the wound and increased sustaining degree for the thoracic cavity during the accomplishment of the surgery; - maintenance of the breathing function; - protection of the endothoracic function; - preserving a certain degree of the parietal extension; - eliminating the possibility of the fluid retention or of blood separation and accumulationwithin the thoracic cavity; and - the option to collagenatethe unreinforced textile support so as the product could be used in other surgical field. These features give the following wider benefits for the product: - obtaining of the competitiveproducts, of high degree of biocompatibility,technicity and biofunctionality; - efficient using of the production capacities within textile industry in order to obtain new products, aiming at improving the living way; - growing degree of accuracy, precision, fiability, durability and utilization safety. - achieving of the “clean” products during life cycle by adopting the international system of quality assurance during manufacturing process; - developingcollaborationrelations between hospitals and clinics and between them and research- development units;and - growing of the turnover and of the profit for the producer and his acknowledgementon the international market.
CONCLUSIONS The results of this research has been nationally and internationally acknowledged and has received the award from the General Association of the Engineers in Romania and the golden medal at the International Hall for Inventions and Innovations in Geneva. Stabilisation of the thoracic wall together with the reconstmction of the soft parts represents two essential components of the thoracic parietal reconstruction after a pariectomy. The purpose of assuring an efficient structural support of the thoracic wall consists in avoiding paradoxal breathing and pulmonar hernia. The product is destined to be used in the case of the parietal faults no matter where they are localised (stem, antem-lateral thoracic wall, posterior scapular thoracic wall etc.) and what is the size of the fault. The product which, by its geometrical, technical, biofunctional and biomedical characteristicshas to meet the imposed requirements such as: adaptability to any shape and size of the fault; malleability; durability in view of avoiding paradoxal breathing; non reactivity at the fluids of human bodies; resistance to infections; and radio transparency. 372 0 Woodhead Publishing Limited, 2010
The developed product represents a great novelty, its inbovative character being given by the whole conception of the article made in conformity with the exigencies specific to the destination, for which they are definite: the type of the used raw material; elaboration and projection of the textile support; establishment of the manufacturing technology so as to ensure the biological; and microbiological, biofunctional and technical characteristics imposed by the actual norms for the products linked to human tissue for minimum 90 days. The paper discussess the product of Romanian conception which was used for obtaining remarkable results both for the parietal stabilisation concerning some previous lateral faults and also for the cases when there was a small fault ( resection of two ribs) for which it was considered as obligatory. The assuring of the stabilisation, especially because of the patients’ age or the breathing hnction alteration as well as the correlation with the international evolution of these category of products, level of biomedical and biofunctional performances, admissibility condition imposed by the European laws in force regarding the fabrication and commercialisation.
REFERENCES 1 P Arnold, C Pairolero, ‘Surgical management of the radiated chest wall’, Plus?. Reconstruct. Surg, 1986 77(4) 605-612.
2 R J Bumard, N Martini,E J Battle, ‘The value of resection in tumors involving the chest wall’, J#Thorac Cardiovasc Surg, 1994 68(4) 530-534. 3 A S Geha, P Bernatz, L Woolner, ‘Bronchogeniccarcinoma involving the thoracic wall. Surgical treatment and prognostic significance.’ J. Thorac. Cardiovasc. Surg, 1997 54(3)389-393. 4 M Kawamura, M Seki, A Yoshizu, ‘Reconstruction of chest wall defects with autogenous ribs grafts’, Japanese JThorac Surg, 1996 49(2) 53-56.
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PREDICTING THE FATIGUE PERFORMANCE OF ENDOVASCULAR PROSTHESES H -('f,
L Wang(1.21, M W
( I , 3)
g
, y Li(lt) and X Liu(')
(1) College of Textiles, Donghua University, Shanghai 20005 1, P R China
(2) The Key Lab of Textile Science L Technology, Ministry of Education, P R China
(3) College of Textiles, North Carolina State University, Raleigh, USA
ABSTRACT Endovascular prostheses, assembled from tubular textile fabric and wire stent components, me deployed and expanded non-invasively from catheters for the repair of aneurysms in medium and large caliber arteries. Now that the implantation procedure is no longer experimental and these devices are becoming widely accepted and used for a growing cohort of patients, so the incidence of reported cases of late complications continues to grow. Observations fiom our own implant retrieval programme have led us to report that certain styles and models of endovascular prostheses are associated with particular failure mechanisms, such as endoleaks, migration, thrombosis, stent disruption, as well as fabric distortion and perforation. There is, therefore, a need to evaluate the fatigue resistance of endovascular devices with the objective of identifyingthose structural features that lead to long term prognoses and those that are associatedwith premature failure. It has already been acknowledged by the FDA and other regulatory agencies that accelerated pulsatile pressure testing of an endovascular prosthesis for over 400 million cycles in a straight configuration does not necessarily predict its in vivo performance over 10 years. We, therefore, propose to evaluatethe fatigue resistance of endovascular prostheses by using an alternative approach, which involves exposing the device to pulsatile flow conditions.We have designed and built an in vitro circuit for this purpose. It consists of a reservoir tank with a heater and temperature controller system to maintain the temperature of the liquid constant, a peristaltic pump, which functions as the heart and provides a physiological pressure waveform at frequencies of 0 - 10 Hz,and on-line pressure sensors that monitor the liquid pressure inside the circuit in real time. The multi-positionspecimen frame enables several test specimens to be mounted and fatigued simultaneously,while the heater and temperature controller ensure that the test conditions are controlled at 3721 degrees C. The paper describes the testing conditions for the fatigue simulation circuit, and how we test the fatigue resistance of tubular fabric specimens with different textile structures. Our study investigatesthe influences of textile structural parameters such as yarn count, woven design, and woven fabric count on the fatigue performance of endovascularprostheses.The ultimate goal is to be able to use accelerated fatigue bench testing to predict the in vivo fatigue life of endovascularprostheses and their susceptibilityto premature failure. 374 0 Woodhead Publishing Limited, 2010
Keywords: endovascular prosthesis; fatigue resistance; in vitro test; stent graft; textile structure.
INTRODUCTION Endovascular prostheses, assembled from tubular textile fabric and wire stent components, are deployed and expanded non-invasively from catheters for the repair of aneurysms in medium and large caliber arteries (Figure 1). Now that the implantation procedure is no longer experimental, these devices are becoming more widely accepted and used for a growing cohort of patients. This has led to a growing incidence of reported cases of late complications. From the observations from our own implant retrieval programme, we have reported that certain styles and models of endovascular prostheses are associated with particular failure mechanisms, such as endoleaks, migration, thrombosis, stent disruption, as well as fabric distortion and perforation (Figure 2) There is, therefore, a requirement to evaluate the fatigue resistance of endovascular devices with the objective of identifying those structural features that lead to long term prognoses and those that are associated with premature failure. It has already been acknowledged by the FDA and other regulatory agencies that accelerated pulsatile pressure testing of an endovascular prosthesis for over 400 million cycles in a straight configurationdoes not necessarily predict its in vivo performance over 10 years '. We, therefore, propose to evaluate the fatigue resistance of endovascularprosthesesby using an alternative approach, which involves exposing the device to pulsatile flow conditions. We have designed and built an in vitro circuit for this purpose. We are investigating the influences of textile structural parameters, such as yam count, woven design, and woven fabric count on the fatigue performance of endovascular prostheses with the help of this circuit. The ultimate goal is to be able to use accelerated fatigue bench testing to predict the in vivo life of endovascularprostheses and their susceptibility to premature failure. This paper describes some of our preliminary findings.
'.
Figure 1 Endovascular prosthesis deployed within an abdominal aortic aneurysm.
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Figure 2 Retrieved endovascular pnxsthesis after 18 months in vivo showing woven fabric distortion.
EXPERIMENTAL Experimental materials A series of tubular fabric samples, typical for use in endovascular prostheses, were woven
fiom polyester monofilament and multifilament yams on a special narrow ribbon shuttle loom3. They were 8 mm in diameter and 6 cm in length, and had the structural specificationslisted in Table 1. Table 1 Textile structural specifications(Monofilamentyarns are designated 11, while multifilament y a m s indicate the number of filaments, e.g. /12)
Sample
Yarn linear density
Fabric count
/ filament count
(ends x picks)
(warp x weft) (denier)
( yamS/lOcm1
Fabric design
No. 1
30/1x 20/1
1580x1330
3/1twill
No.2
30/1 x 20/12
1560x 1260
2/2 twill
No. 3
30/1 x 20/1
1600x1350
212 twill
No.4
30/1 x 20/12
1600x1060
3/1 twill
Simulation of fatigue behavior The fatigue tester used in this study was specially designed and built by our team for this research project. The test system consists of a peristaltic pump, which generates the pulsatile flow (Figure 3). 376 0 Woodhead Publishing Limited, 201 0
pa.nns.anrG7
-
Water is used because it dose not affect the surface properties of the prosthesis and because its relative density is close to that of blood. At 37°C: pwater = 1.00 g/cm3; p blood = .04 gkm3*4. The test system also consists of a multi-position specimen frame for mounting the prosthesis specimens in series, a reservoir tank with a heater and temperature controller for maintaining the temperature of the water at 37+1"C, a check valve, which limits fluid flow and increases the pulsatile pressure on the specimen, and an on-line pressure sensor measuring the pulsatile pressure of the fluid in real time. The pressure waveform experienced by the prosthesis is displayed on a computer monitor. The tubular textile fabric samples were mounted in a relaxed state in the specimen frame with an elastic latex tube inside to ensure that the pressure profile of the fluid was transferred to the specimen. With the objective of accelerating the rate of fatigue testing, the ficquency of the peristaltic pump was selected at 10 Hz,and the internal pressure generated in the circuit was much higher than normal systolic blood pressure of 120 mm Hg. The four samples were placed in the fatigue tester in two groups and tested under the conditions shown in Table 2. Table 2 Test conditions in the fatigue tester Sample
No. 1 andNo. 4 No.2 and No. 3
Pressure range Ma)
Frequency
540-330 450-260
10
Total number of cycles
(Hz) 10
720,000 720.000
While we tested the samples for a total number of 720,000 cycles, after 486,000 cycles the tester was stopped and measurements of the woven fabric count were made.
Evaluation of fatigue properties An important objective of this preliminary experiment was to monitor any changes in the structural properties of prosthetic fabrics during accelerated fatigue testing. First the woven fabric count, including the warp density and weft density, was measured using the 0 Woodhead Publishing Limited, 2010 377
image captured by a camera on a low power microscope and displayed on a KH-1000 video unit. The fabric thickness was measured according to the Chinese standard test method GB1380-1997, and the fabric weight or mass per unit area was determined by weighing a known area of the specimen on an electronic balance with an accuracy of +1 mg. The density of the polyester fibers was assumed to be 1.38 g/cm3. All tests were performed in at least triplicate. These data enabled the fabric porosity to be calculated using the following formula
':
P=lOOx ( 1- "
) % txpxlOOO
M--- Weight ofthe fabric specimen (s/m2); t - Thickness of the specimen (mm); p --- Density of the polymer or fibre (g/cm3).
RESULTS AND DISCUSSION The average values for the fabric structural parameters of the four samples before and after fatigue testing are shown in Table 3. Table 3 Mean fabric structural parameters before and after fatigue testing
No. of sample
I
2
3
4
Textile structure Warp density (enddlocm) Weft density @icks/lOcm) Thickness (mm) Porosity (%) Warp density (enddlOcm) Weft density @icks/lOcm) Thickness (mm) Porosity ( %) Warp density (enddlOcm) Weft density @icks/lOcm) Thickness (nun) Porosity (YO) Warp density (ends/lOcm) Weft density (picks/lOcm) Thickness (mm) Porosity (%)
Number of cycles 0 (Control)
486.000
1580 1330 0.149 51.100? 1560 1260 0.124 38.12% 1600 1350 0.123 41.36% 1600 1060
1430 1280
0.099 21.38%
-I
1550 1220
720.000 1400 1280 0.160 54.70% 1530 1200 0.135 41.02% 1460 1290 0.124 44.81% 1480 1000 0.122 35.47%
From Table 3 we can see that exposureto fatigue testing causes the woven fabric count to decline and the porosity to increase. This indicatesthat the fabric samplesundergo fatigue and experience stretching and dilation. For all four samples the fall in warp density is more noticeable than in the weft density, suggestingthatthe effect of pressurizedpulsatile 378 0 Woodhead Publishing Limited, 2010
flow is greater in the radial direction is more remarkable than in the longitudinal direction. Regardless of the woven fabric structure and yarn size, during the initial period of fatigue (i.e. during the first 486,000 cycles) the loss in weft density (picks per 10 cm) is more pronounced than during subsequent fatigue cycles. This is not the case for the loss in warp density (ends per 10 cm), which appears to continue to fall in a more linear fashion. This suggests that under these particular pulsatile flow or separation conditions, realignment of the weft yarns reaches a new equilibrium in the longitudinal direction before the radial spacing of the warp yarns has achieved a steady state. In other words, the applied pulsatile flow system continues to cause more evident fatigue stress in the radial direction than in the longitudinaldirection. Differences in fatigue behaviour were also observed between Sample No.1 with a monofilament weft yam, and Sample No.4 with a multifilament weft yam. In the case of SampleNo.1 with the monofilament weft, most of the loss in warp density, i.e. separation of the warp yarns caused by stretching or realignment of the weft picks, occurred during the initial fatigue period, with only minor changes being observed during the second part of the test period. In comparison, the warp density of Sample No.4 with the multifilament weft yarn continued to experience significant changes in warp density throughout the whole fatigue testing regime. This points to the fact that multifilament yarns have more fieedom to realign under continual pulsatile stresses, and so take longer to reach an equilibrium state compared to monofilament yams.
CONCLUSIONS An in vitro fatigue tester with pulsatile flow has been designed and built to test the tubular
fabric component of endovascular prostheses. Preliminary experiments have demonstrated that under accelerated conditions of high pressure and high frequency, polyester woven fabric samples do experience some fatigue. Generally speaking, the higher the pulsatile pressure and the higher the frequency,the faster the specimensfatigue. Significant changes of textile structural parameters were observed. In particular, consistent losses in end and pick densities, and increases in fabric thickness and porosity, suggest that the fabrics experienced dilation and stretching as part of the fatigue process. Our work is continuing, and we are evaluatingthe relative fatigue behaviour of woven endovascular prosthetic fabrics with and without stents. More detailed analysis of the influences of fabric design on the fatigue behaviour is also under investigation. ACKNOWLEDGEMENT
Sponsoring fund: Financial support provided by the Government of P. R. China, 111 Project B07024 “Biomedical Textile Materials Science and Technology”.
REFERENCES 1 R Guidoin, Y Marois, Y Douville, M W King et al, ‘First-generationaortic endografts: Analysis of explanted stentor devices from the EUROSTAR Registry’, Journal of 0 Woodhead Publishing Limited, 201 0 379
Endovascular Therapy,2000 7(2) 105-122. 2 D W Feigl, FDA Public Health Notification. ‘Problem with endovascular grafts for treatment of abdominal aortic aneurysm (AAA)’,US Food and Drug Administration, Center for Devices and Radiological Health, April 27, 2001. http://www.f~gov/c~~s~e~/~h~l
3 Z Shuyao, L Yuliig, ‘Research and development of endovascular prostheses and their performances’, Master Degree Thesis, Donghua Universily, Shanghai,P.R. China, 2003. 4 A Saber, M Sofiene, B Habib et al. ‘Mechanicalbehavior of a textile polyester vascular prostheses: Theoretical and experimental study’, TextiZe Res. J , 2005 75(ll) 784-788. 5 J Lixia, W Lu,‘The design of vascular prostheses’ Permeability Test Instrument and the Research about Characterization of Vascular Prostheses’ Permeability’, Master Degree Thesis, Donghua University, Shanghai, P.R. China,2004.
380 0 Woodhead Publishing Limited, 2010
INTEGRATION AND EMBEDDING OF VITAL SIGNS SENSORS AND OTHER DEVICES INTO TEXTILES M. J. Abreu, H. Carvalho, A. Catarino, A. Rocha, Universidade do Minho, Department of Textile Engineering, Campus de A m e m - 4810-058 Guimarks, Portugal - e-mail:
[email protected];
[email protected];
[email protected];
[email protected] ABSTRACT The development of ubiquitous vital sign monitoring has become a very up-to-date research theme for many academics and industrial companies in the last years. With new materials and integration techniques, it is possible to implement vital sign monitoring in an economic manner, directly into textile products. This unobtrusive presence of sensors is especially important for the monitoring of children or elderly people. This paper focuses on two aspects of sensor integration: Integration of off-theshelf electronic components, and the use of the textile material itself as sensor, or in general as an electrically active element presenting some exploratory work in the integration of electronic devices into textiles. The main objective was to reproduce and improve on previous work presented by other authors, and foster possibilities of developing garments for vital sign monitoring with immediate industrial and economic feasibility. The use of standard production techniques to produce textile-based sensors, easily integrated into garments and with mass-market potential, is one of the important motivations for this work.
INTRODUCTION Regarding the integration of electronics into textiles, it is possible to consider various levels of integration. In a first level, commercially available electronic components are integrated into garments using special design elements fitted to the textile product exclusively to allow the introduction of the external component@).In the next level, the textile material itself is used as an electrically active component. Its function is provided by the properties of the base material, by structural properties or by introducing electrically active textile elements by embroidery. A further step would be to implement electronic circuits within the fibres themselves, but at the time being technology is still far from providing tools to achieve this intent. The growing availability of flexible and miniaturised sensors and electronic components has made the first level of integration quite straightforward.Regarding the embedding of the sensors into the textiles, more advanced techniques are required, A first step is to implement the sensors using textile materials based on conducting yams or yarns with sensing properties (piezoelectric, optical fibres). Still, all the signal treatment has to be done outside the textile, by means of a dedicated electronic device. The authors of this paper have conducted some exploratory experiments with several techniques intending to achieve measurement of heart beat and respiratory rate, using both inexpensive off-the shelf sensors and piezoelectric polymer sheets, as well as fabrics knitted with conducting yarns, acting as sensors.A review of the state-of-the-art, an overview of general principles and the results obtained in the experiments will be discussed.
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REVIEW OF THE STATE OF THE ART Several efforts to create prototypes of wearable functional devices have been made in the last years. Most of them consider the approach of joining conventional off-the-shelf electronic devices to fabrics, such as microcontrollers, LED’S, optical fibres and all kinds of sensors, especially electrodes for ECG measurement. The consolidated textile technology for integrating conductive yarns into knitted or woven fabrics and the implementation of sensors through embroidery has encouraged their use as suitable means for connection, data communicationand power transfer. The following paragraphs will outline contributionsto the e-textile field which were developed by several research groups in the last few years, taking into account the performance of the devices. In the 1990s, Lind et a1 from the Georgia Institute of Technology in AtlantaAJSA developed a so-called Smarrshirr 0, where off-the shelf sensors could be reversibly attached for monitoring several vital signs. Later on, the same authors developed an instrumented uniform called Sensate Liner which consists on a form fitting garment containing and interconnecting textile sensing elements to an electronic pack equipped with a processor and a transmitter. This uniform was developed for monitoring the medical condition of military personnel 0. A baby pyjama with integrated sensors 0 is conceived as a prevention tool for the sudden infant death syndrome, operating an alarm in case of potential danger. The babysuit uses textile ECG electrodes and a respiration sensor both knitted from stainless steel yarn. Ottenbacher et a1 (University of Karlsruhe) [4] integrated an ECG system with Bluetooth communication into a T-shirt. Some of the components are incorporated into the garment, while the flexible electronic system is removable so that the garment can be washed. ETH of Zurich/Switzerland developed e-textiles for functional electrical stimulation, embedding electrodes by using embroidey techniques for the integration into a textile substrate of conducting yarns, made of silver coated fibers 0. Paradiso er a2 (University of Pisa) and Smartex in Italy developed a system named REALTHY, where conducting and piemresistive materials in form of fibres and yarns are integrated in a garment and used as sensor and electrode elements to assist cardiac patients during rehabilitation or professional workers that are under considerable physical and psychological stress 0. Many more authors have provided important contributions to this area. The selection here presented reflects the most important work in the context of the current paper.
OVERVIEW OF GENERAL PRINCIPLES A definition for e-textiles (electronic textiles) could be a multifhctional wearable human interface, capable of making daily life healthier, safer and more comfortable, integrating sensing or stimulation properties, capable of transmitting and processing data. As previously described, to develop such an interface, there are two possibilities: Using commercially available sensors adequate for integration into textiles; and implementing the sensors using textile materials. The commercial sensor used in this work is piezoelectric film, sensors that are based on a polymer that exhibits the piezoelectric effect. In piezoelectric materials, a voltage appears as a consequence of mechanical stress. This effect is reversible, i.e, a piezoelectric material will produce a mechanical action when excited by an electrical potential. The use of polymers printed on flexible sheets allows the production of extremely flexible and sensitive sensors that can be integrated into textiles with relative ease. 382 0 Woodhead Publishing Limited, 201 0
Considering that any electrical conductor varies its resistance according to temperature and also according to strain, it is theoretically possible to use this effect for sensing purposes by integrating electrically conductive yarns into textiles. The general principle of the textile sensors tested in this work is based on the variation of electrical resistance with strain. This can be achieved by applying the stress directly to the yarn. It is also known that fabrics knitted with conducting yarns vary their overall electrical resistance depending in the extension they are subject to, thus behaving as extension sensors 000. Another way of producing textile sensors is through embroidery, using conductive threads 0. Several possibilities of inductive, capacitive or resistive sensors (sensors varying inductance, capacitance or resistance with geometrical, physical influences or chemical influences) exist, but were not explored in this work.
EXPERIMENTAL, RESULTS AND DISCUSSION Respiratory rate and heart beat freqneney with piezoelectric film integrated into textile The device was based on a DT-Series piezo film with lead attachments, from Measurement Specialties Inc (Figure 1 left). The sensor was integrated into an accessory that is clipped onto a strap with standard garment clips. The electrical connection of the sensor is embroidered onto the textile substrate receiving the sensor, and a female garment clip is applied onto the embroidered contact to serve as an electrical connector. The cable receives the male part of the clip (Figure 1 right).
Piezoelectric film sensor
Measurement accessory
Figure 1. Piezoeledc sensor integrated on textile.
The piezoelectric sensor is then connected to a charge amplifier' designed to assure an appropriate low-frequency response to accurately display the relatively slow breathing movement. A simple Labview program was developed to display the signal in a PC equipped with a data acquisition board. As expected, the piezoelectric sensor revealed extremely sensitive and does not cause any discomfort due to its flexibility. The breathing movement is clearly depicted (Figure 2).
'
A charge amplifier is an electronic circuit specificallyused for the conditioning of signals from piezoelectric sensors.
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Figure 2. Breathing signal acquired by piezoelectric film sensor (x-scale: Time, y-scale: Volt).
Superimposed on the breathing signal it is possible to observe the heart beat signal, although this component only becomes evident when the wearer holds his breath (Figure 3). It is possible to extract the heart beat fkquency by using spectral analysis techniques. Unfortunately, the sensitivity of the sensor is also a disadvantage, considering that any movement by the wearer may blur the remaining signals for analysis. A low-pass filter at about 1Hz could solve this problem, but it would also filter out the heart beat component, leaving only the breathing signal. Simple movement detection is extremely efficient with this sensor, and in this case the assembly could be redesigned for more wearing comfort.
Figure 3. Heart beat signal acquired by piezoelectric film sensor (x-scale: Time,y-scale: Volt).
Respiratory rate: Textiles used as extension sensor Following up on the work that used knitted fabrics as extension sensors to measure breathing rate 000, some samples were knitted in three different structures, using a yam that is a blend of polyester and stainless steel in a proportion of 80/20% (Bekaert Bekinox@Nm 50) and has a perfectly "textile" touch comparing to a pure stainless steel yarn. The first experiments showed that the sensors had limited performance. The main problems presented by this sensor are its high non-linearity and hysteresis, and an evident instability of the electrical resistance values measured, producing a fluctuation of the signals. Still, it was possible to develop a measurement accessory (Figure 4) and obtain interesting signals, as shown in Figure 5.2
The signal conditioning was in this case achieved by an operational amplifier in an inverting configuration and using the sensor as feedback resistance, thus amplifying a reference voltage in proportion to its electrical resistance. 384 0 Woodhead Publishing Limited, 201 0
Figure 4. Accessory using knitted fabric as extension sensor.
Figure 5. Breathing signal acquired by knitted sensor (x-scale: Time, y-scale: Volt).
To improve the sensor’s behaviour, new sensors were produced and tested with more detail. A rib 1x1 structure based on the Bekinox yarn and plated with Spandex@was produced. Spandex@was used in order to improve the capability of the fabric to completely recover the initial physical characteristics and hopefully the electrical properties. The samples were inserted into a Houndsfield dynamometer with the intent to exactly control the extension applied to it and observe the behaviour of the electrical resistance when subjected to consecutive ascending and descending excursions of extension. The experiment showed that the rib fabric has a nonlinear behaviour with respect to electrical resistance variability, with severe differences in resistance between ascending and descending excursions, particularly for low extensions. For higher extensions the resistance has a small non linearity (Figure 6, right). Between 60 and 72 mm, the electrical resistance presents a quasi linear behaviour. 5,
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Figure 6. Electrical resistance variability for Rib 1x1 with Spandex@(sample of lOcm length x 4 cm width).
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The other structure was Jersey, again plated with
[email protected] 7 illustrates the resistance curve for this stmctme when the axial tensile force is applied in the wale direction. With this configurationthe resistance is quite high and measured in Mn. The general behaviour is quite similar as for rib since the resistance falls down as the extension increases. However, there is a significant decrease in resistance for higher extensions, namely on the 20-25 mm range. It is also possible to observe that from 12 mm up to 25 mm one can find a relatively well behaved resistance curve. The plausible explanation for the relatively high resistance can be found in the structute of jersey. There is not a natural path for the current to flow as it happens when the resistance is measured in the course direction. The current flows throughout each contact between a loop located of the previous c o m e and a loop of the course immediately located above (or below). This results in a small metallic contact surface, thus resulting in a higher resistance. On the contrary, the electrical conductivity of jersey fabric when measured in a course direction is quite increased since the yarn is part of each loop of that course. As a consequence, the resistance dramatically decreases.
o
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Figure 7. Electrical variability for jersey fabric. Sample of 4cms length x 5 cms width.
Nevertheless, it was not possible to obtain a significant improvement in this second experiment with knitted sensors. Important chatacteristics such as linearity, hysteresis, repeatability and the sheer stability of the measured values are not fully satisfying. Further attempts are planned, using different dimensions for the sensors, and inserting Spandex@into the fabric in different ways. An interesting idea is to use the yarn itself as the extension sensor, possibly inserted into a plain weave. To investigate on this approach, some measurements were made on yarn samples.Before performing the experiments, the stress-strain curve for this yarn was obtained using standard IS0 2062 and the elastic zone identified. The yam was then submitted to axial traction up to the maximum extension where the elastic zone is available and in predetermined extensions the electrical resistance was measured. As Figure 8 illustrates, the yarn presents a hysteretic behaviour, with the electrical resistance decreasing as long as the yarn is extended, starting from 1.25 kl2 for 0 mm up to 0.90 kf2 for 15 mm. The resistance variability has a nonlinear behaviour, but unlike the knitted samples, the resistance values measured are quite stable. A careful observation of this figure suggests that there might be an extension interval, from 5 to 10 mm, where the yarn can be considered as having a linear behaviour. In fact, the regression lines are quite similar for that region.
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1.35
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Figure 8. Electrical resistance versus extension for conductive yam. Sample length 50 cms.
When subjecting the same sample to consecutive excursions, one can observe the general nonlinear behaviour (Figure 9). However, it is evident that stretching and afterwards releasing the yarn results in a significant increase of the resistance, in particular for low extensions. The descending excursions reveal a marked nonlinearity. On the other hand, the ascending excursions indicate that the nonlinearity is not so evident. From the observations made, it seems clear that a predefined tensile force should be used and thus the yam stretched only from a predefined extension up to the highest extension. This procedure would probably allow repeatability for the electrical resistance. z45 225 2.05 1,BS
1 K
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Figure 9. Consecutive excursionson the same conductive yam.
CONCLUSIONS The possibility of using more or less conventional textile materials to implement sensing fimctions is feasible, but the performance of the proposed devices is quite limited. It seems that the sensors are able to provide repeatability only on segments of the measuring range. Both the structure of the yarn as well as the knitted structure of the fabric are quite complex. The contacts between the conducting fibres in these arrangements determine the electrical resistance of the sensor. However, in consecutive extensions the arrangement of the yarns and conducting fibres is always slightly different, thus negatively influencing repeatability. Further optimisation may be achieved in future work, but it will be difficult for these devices to fulfil fill medical requirements, especially considering the day-to-day use and care they are subject to. More advanced materials, using piezoresistive and piezoelectric coatings on a filament 0 Woodhead Publishing Limited, 201 0 387
level, and inserted into fabrics through weaving or embroidery, are more likely to achieve the desired accuracy.
REFERENCES 1 Eric J. Lind, Sundaresan Jayaraman, Sungmee Park, Rangaswamy Rajamanickam, Robert Eisler, George Burghart, Tony McKee, ‘A Sensate Liner for Personnel Monitoring Applications’, First int symp on Wearable Computers (lSWC ‘97), page 98, 1997.
2 F Carpi, D Rossi, ‘Electroactive Polymer-Based Devices for e-Textiles in Biomedicine’, IEEE Transactions on Information Technology in Biomedicine, 2005 9(3). 3 M Catrysse, R Puers, C Hertleer, L Van Langenhove, H van Egmond, D Matthys, ‘Towards the integration of textile sensors in a wireless monitoring suit’, Sensors and Actuators, 2004 A 114 302-3 11. 4 J Ottenbacher et al., ‘Integration of a Bluetooth Based ECG System into Clothing’,
8th int Symp on Wearable Computers, Arlington (USA), 2004. 5 T Kirstein, M Lawrence, and G Trtister, ‘Functional electrical stimulation (FES) with
smart textile electrodes,’ Proc. Int. Workshop New Generation Wearable Syst. for eHealth: Toward Revolution of Citizens >Health,Life Style Management, Lucca, Italy, 2003,201-208. 6 R Paradiso, G Loriga, and N Taccini, ‘Wearable Health Care System for Vital Signs Monitoring’, MEDICON 2004 Conference, Naples (Italy), 2004. 7 H Zhang, X Tao, ‘Electro-Mechanical Properties of Knitted Fabric Made From Conductive Multi-Filament Yam Under Unidirectional Extension’, Textile Res. J, 2005 75(8) 598-606. 8 R Paradiso, G Loriga, N Taccini, ‘A Wearable Health Care System Based on Knitted Integrated Sensors’, IEEE Transactions on Information Technology in Biomedicine, 2005 9(3).
9 E R Post, M Orth, P R Russo, N Gershenfeld, ‘E-broidery: Design and Fabrication of textile-based Computing’, IBMSystems Journal, 2000 39(3/4).
388 0 Woodhead Publishing Limited, 2010
PART VI MEDICAL DEVICES
TEXTILE-BASEDMEDICAL DEVICES: AN OVERVIEW J. F. Kennedy and C. J. Knill Chemical Laboratories, Advanced Science and Technology Ltd, Bromsgrove, Worcestersbire, B60 4JE,UK
WHAT IS A MEDICAL DEVICE? The EU (Directive 2007/47/EC) defines a medical device as:
‘Anyinstrument, apparatus, appliance, sofiware, material or other article, whether used alone or in combination, including the sojhvare intended by its mangacturer to be used specifcally for diagnostic a d o r therapeutic purposes and necessary for its proper application, intended by the manufacturer to be usedfor human beings. ’ MEDICAL TEXTILES & THEIR APPLICATIONS The world textile industry is moving rapidly toward the manufacture of high-added value textile structures and products such as medical textiles, protective textiles and smart textiles. Textile materials used in medical devices are an important and growing part of the textile industry. Textiles present an excellent interface between the human body and medical treatment, and thus their continued development is an important part of medical diagnosis and therapy. Medical textiles embrace all those textile materials used for medical devices in health and hygiene applications in both the consumer and medical markets, thus comprising a group of products with considerablevariations in terms of product performance and unit value. Categories of medical textiles include non-implantable materials, implantable materials, healthcare and hygiene products, and extracorporeal devices. The application of different fibres for fabricating medical textiles for medical devices is illustrated in Tables 1-3, which focus on non-implantables, implantables, and healthcarehygiene, respectively. Examples of medical textiles used in extracorporeal medical devices include the use of hollow fibres and membranes (made from polyester, polypropylene, silicone, viscose) for production of bioartificial organs, such as the kidneys, liver and lungs.
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Table 1. Non-implantable medical textiles [l".
Fibre componenta Alginate chitin / chitosan Chondroitin Cotton Hyaluronan Polyamide Polyester Polyglycolide Polylactide Polypropylene Polyurethane Silk Viscose Wood pulp
Fabric structures
Air layered Knitted Needle-punched Non-woven Spunlaid Woven
Application areas Absorbent pads Base materials Compression bandages Elastic bandages Gam dressings High-support baudages Lint Non-elastic bandages Orthopaedicbandages Plasters Scaffold wadding Wound-contact layers
Table 2. Implantable medical textiles ['x541.
Fibre components chitin / chitosan Chondroitin Collagen Hyaluronan Polyamide Polyester Polyethylene Polyglycolide Polylactide Polypropylene PTFE & PMMA Silicon Silicone Silk
Fabric structures Braided Knitted Monofilament Non-woven Woven Embroidered Crocheted Composites
Application areas Artificial cartilage Artificial cornea Artificialjoints / bones Artificial ligament Artificial skin Artificial tendon Biodegradable sutures Eyecontact lenses Heart valves Non-biodegradable sutures Tissue engineering scaffolds vascular grafts
Table 3. Hedthcare / hygiene products utilising medical textiles "2*91.
Fibre components
Fabric structures
Application areas
Cotton Polyamide Polyester Polyethylene Polypropylene Superabsorbents Viscose
Knitted Non-woven Woven
Absorbent products Blankets / sheets / pillowcases Cloths / wipes Protective clothing Surgical caps, gowns, masks surgical drapes Uniforms 392 0 Woodhead Publishing Limited, 201 0
Application areas covered in this chapter include sutures, dental tape, maternity support garments, vibration suppression, fibre functionalisation, and early cancer detection. Specific topics include: investigations into hcture mechanisms of some non-absorbable sutures in vivo; the properties of absorbablehon-absorbable sutures; controlled fluoride release from extruded aromatic-aliphatic co-polyester dental tape; gas plasma modification of polypropylene dental floss surfaces; design and materials for maternity support garments for lower back pain relief; microwave radiometry for early detection of sub-tissue oncological imperfections, and enzyme catalysed coupling of functional molecules onto wool fibres for increased antioxidant activity.
BIOMATERZALS USED IN MEDICAL TEXTILES Carbohydrate polymers (polysaccharides) are one of the most common classes of biomaterials used for the roduction of medical textiles (filaments, fibres and fabrics) for use in medical devicesRA. The repeating units present in the structures of cellulose, chitin, chitosan, alginate, hyaluronan, and chondroitin sulphate, are presented in Figure 1 [3*41. The major sources of cellulose are cotton and wood pulp. Methods of cellulose processing andor modification were developed to produce flexible woven fibres (from cotton and viscose), which are used to produce a wide range of wound dressings, such as retention bandages, support and compression bandages, absorbents, gauzes, tulle dressings, etc 13]. Chitin is found in the exoskeleton of crustaceans, and chitosan is the partially deacetylated form of chitin. Chitin and chitosan are biocompatible (since their biodegradation products are natural metabolites), and they can be produced in powder, film, bead, fibre and fabric form *3,4.117121. Alginate is obtained from the cell walls of brown algae (Phaeophyta) such as the seaweeds Laminaria sp. and Ascophyllum sp. Alginate filamentdfibres are generally produced by wet-spinning by injecting a solution of sodium alginate into a solution containing a calcium salt andor acid (producing insoluble calcium alginate andor alginic acid filamentdfibres). Such fibres are used to produce woven and non-woven fabrics for medical device applications R4J 1.13-171 . Hyaluronan is widely distributed in the connective tissue and vitreous and synovial fluid of mammals, acting as a lubricant and shock-absorbing material in the fluid of joints. Commercial sources include Cock's combs, human umbilical cords and fermentation (Streptococcus equg [3fl. It can be used in its esterified form for tissue engineering applications [' I. Chondroitin sulphate is a sulphated polysaccharide found in the extracellular matrix of connective tissues as well as cartilages, tendons and the cornea. Commercial sources include bovine and porcine trachea, and certain fish species.
Figure 1. Chemical structures of carbohydratepolymers used in medical textiles [3s41. 0 Woodhead Publishing Limited, 2010 393
REFERENCES 1 R Czajka, ‘Development of medical textile market’, Fibres & Textiles,2005 13 13-15. 2 S Rajendran and S C Anand, ‘Development in Medical Textiles’, Textile Progress, 2002 1013. 3 J F Kennedy, C J Knill and M Thorley, Natural polymers for healing wounds, In: Recent Advances in EnvironmentalbCompatible Polymers, J F Kennedy, G 0 Phillips, P A Williams & H Hatakeyama (eds), Woodhead Publishing Ltd,Cambridge, UK, 2001,97-104. 4 J F Kennedy and C J Knill, Biomakrials utilised in medical textiles: an overview, In: Medical Textiles and Biomaterialsfor Hedthcare, S C Anand, J F KeMedy, M Miraftab & S Rajendrau (eds), Woodhead Publishing Ltd, Cambridge, UK, 2006,3-22.
5 S C Anand, Implantable devices: an overview, In: In: Medical Textiles and Biomaterials for Healthcare, S C Anand, J F Kennedy, M Miraftab & S Rajendran (eds.),Woodhead Publishing Ltd,Cambridge, UK, 2006,329-334. 6 V M Comlo, M E Gomes, K Tuzlakoglu, J M Oliveira, P B Malafaya, J F Mano, N M Neves
and R L Reis, Tissue engineering using natural polymers, In: Biomedical Polymers, M Jenkins (ed.), Woodhead Publishing Ltd,Cambridge, UK, 2007, 197-217. 7 T Freier, R Montenegro, H Shan Koh and M S Shoichet, ‘Chitin-based tubes for tissue engineering in the nervous system’,Biomateriah,2005 26 4624-4632. 8 J M Pachence and J Kohn, Biodegradable polymers for tissue engineering, In: Principles of Tissue Engineering, R Lanza,R Langer & W Chick (eds.), Academic Press, New York, USA, 1997,263-272. 9 S C Anand, Healthcare and hygiene products: an overview, In: Medical Textiles and Biomaterials for Healthcare, S C Anand, J F Kennedy, M Miraftab & S Rajendran (eds.), Woodhead Publishing Ltd, Cambridge, UK, 2006,75-79. 10 R A A Muzzarelli, M Mattioli-Belmonte, A Pugnaloni and G Biagini, Biochemistry, histology and clinical uses of chitins and chitosans in wound healing, In: Chitin and Chitanuses, P. Jollks & R A A Muzzarelli (eds.),Birkhiiuser Verlag, Basel, 1999,25 1-264. 11 Y Qin, 0 C Agboh, X Wang and D K Gilding,Novel polysaccharide fibres for advanced wound dressings, In: Medical Textiles 96, S C h a n d (ed.),Woodhead Publishing Ltd, Cambridge, UK, 1997, 15-20. 12 Y Qin and 0 C Agboh, ‘Chitin and chitosan fibres: unlocking their potential‘, Medical Device Technology, Dec (1998) 24-28. 13 M Mirafiab, Q Qiao, J F Kennedy, S C Anand and G Collyer, Advanced materials for wound dressings: biofimctional mixed carbohydrate polymers, In: M e d i d Textiles, S C Anand (ed.), Woodhead Publishing Ltd, Cambridge, UK, 2001, 164-172. 14 S Thomas, ‘Alginatedressings in surgery and wound management - Parts 1-3’, Journal of W d C a r e , 2000 9 56-60; 115-119; 163-166. 15 Y Le, S C Anand and A R Horrocks, Using alginate fibre as a drug carrier for wound healing, In: Medical Textiles 96, S C Anand (ed.), Woodhead Publishing Ltd, Cambridge, UK,
1997,21-26. 394 0 Woodhead Publishing Limited, 2010
16 Y Qm and D K Gilding, ‘Alginate fibres and wound dressings’, Medical Device Technology, Jul(1996) 32-41. 17 C J Knill, J F Kennedy, J M h y , M Miraftab, G Smart,M R Oroocock and H J Williams, ‘Alginate fibres modified with unhydrolysed and hydrolysed chitosans for wound dressings’, CarbohydratePolymers, 2004 55 65-76.
18 D Williams, ‘The engineering of polysaccharides’,Medical Device Technology, Sep (1997) 8-11.
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DESIGN AND RELEASE RATES OF A NOVEL BIODEGRADABLE SLOW-RELEASEIMPLANT FOR THE PREVENTION OF PAEDIATRIC DENTAL CARIES G.J.Dunn A.F.Fotheringham School of Textiles and Design, Heriot-Watt University,UK
ABSTRACT The aim of this study was to investigate the design possibilities and fluoride release rates for a novel biodegradable slow-release device for the prevention of paediatric dental caries. The design possibilities include colour, shape, size and placement within the buccal cavity. The release rate of fluoride was analysed on a weekly basis to examine the potential as a slow-release device, which would allow a constant level of fluoride to be present in the mouth over a period of weeks or months depending on the patient’s circumstances.
INTRODUCTION Dental caries is the most common oral disease and usually begins in childhood. It affects a large percentage of children and adults worldwide. The aim of this research was to develop a biodegradable slow-release device for the prevention of paediatric dental caries. The device consists of three layers. The top layer is a polysaccharide, which releases a flavouring and degrades within seconds upon placement in the buccal cavity. The middle layer is a biodegradable hydrogel which releases an antibacterial agent over a number of hours and the bottom layer, which will be discussed in this paper, is a novel starch based biopolymer which releases sodium fluoride over several W€%kS.
Sodium fluoride remindises areas of the teeth that have been damaged by the decay and can prevent caries [I]. It is currently available in tablet and gel forms, which are prescribed by dentists, or more commonly in toothpaste[2]. The current prevention methods rely on patient compliance of brushing their teeth twice a day, flossing and regular dental checkups. A slow release device would not rely on patient compliance which would be ideal for children and a study by Peretz e l al found that parents were interested in preventative non invasive methods of treatment [3]. Constant levels of fluoride present in the mouth can remineralise caries [4] and Mirth identified that a slow release device was ideal for constantly releasing fluoride into the buccal cavity [5]. MATERIALS AND METHODS
Mate* Aliphatic-aromatic copolyester pellets were purchased fiom Rodenburg Biopolymers (Netherlands)and Sodium Fluoride was purchased fiom Alfa Aesar.
Methods Films were produced using a 2 roll mill (David Bridge and Co Ltd 63.M.283A). A predetermined weight of polymer pellets were placed in the mill and homogenously 396 0 Woodhead Publishing Limited, 2010
mixed with sodium fluoride powder at 5, 8 and 10% (w/w). The dyed samples were created in an identical manner but the food colourant was added at the 2 roll mill stage. The band that was produced was then constructed as film using a compression moulder (Moore, England). Tapes were produced by extruding the polymer pellets using a single screw bench extruder according to manufacturer's instructions. The pellets were blended with sodium fluoride powder, 0.5,5 and 10% (w/w).
In vitro release experiments Fluoride release from the polymer tapes was measured using a Cole Parmer fluoride ion selective epoxy body electrode (27540-14). The electrode was calibrated daily using known fluoride calibration solutions. The samples were conditioned for 24 hrs prior to the start of the experiment (65 f 2% RH 2 M 2"). The samples in triplicate were placed in 50 mL. deionised water (control), 50 mL phosphate buffer solution pH 7 (similar to human saliva) or phosphate buffer solution pH 7 with 0.24 mL a-amylase (Sigma). Each sample of film was 1 cm2with an average thickness of 0.22 mm. The release rate of fluoride was measured weekly and the results were expressed as ppm (m&).Each sample of tape was 1 x 1 cm or 6 x 1 cm.
RESULTS AND DISCUSSION Design possibilities for buccal cavity There are six design possibilities for placement of the device within the buccal cavity. All six designs could be achieved with the device in a tape profile but only design possibilities 4 and 5 could be achieved using the device as a film profile. The device may be cut to a predetermined size in order to fit the patient's buccal cavity. The most promising designs for the device are designs 4 and 5. Design 4 would require the device to be placed between two molars, which would allow for secure attachment and minimise the potential of it becoming dislodged. It would also be discreet which some patients may find appealing as it would be barely visible. Once in place the device would treat the whole buccal cavity but placement may be selected so that the device is in direct contact with the molars most affected by the caries for maximum remineralisationbenefits of the sodium fluoride. One device could be used to treat the entire mouth. By placing it between two teeth it would not be adversely affected by the mechanical action of tooth brushing which could contribute to a loss of tensile strength and advanced degradation of the device. This design possibility could be constructed using either the tape or film profile depending on the release rate of sodium fluoride required for the patient. Design 5 could either be in tape or film profile depending upon requirements as mentioned above. This design idea would allow treatment to be possible for patients wearing fixed orthodontic appliances. The device would replace one of the brackets on the brace and would be securely fixed in place by acid etching onto the tooth surface and the brace wire. There are limitations to designs 1, 3 and 6. The main concern is loss of mechanical properties by the abrasive action of toothbrusing. If the brushing causes abrasions then the loss in tensile strength may result in the device becoming loose or holes forming which would cause the device to break. Even if they were accidentally swallowed the amount of fluoride present in the devices are within the safe dosage level 0 Woodhead Publishing Limited, 201 0 397
so toxicity would not be a problem. The other limitation is that children may play with the device which would cause dislodging and therefore ineffective treatment. Design1 : This device would wrap around all of the teeth.
Design 2: This device would wrap around one molar
Design 3: This device would wrap around four teeth.
Design 4: This device would sit between two molars
398 0 Woodhead Publishing Limited, 2010
Coloar possibilitiea The device in its natural state is colourless which means that it would be barely visible when inserted into the buccal cavity regardless of which design possibility was selected. The device can also be coloured using natural food dyes, which allows the patient the opportunity to select the colour of their device which may encourage a 'fun' element to the treatment and therefore encourage children to be willing participants. The dye is added at the processing stage and the dye remains within the device even as degradation occurs so there would be no tooth staining . Food colouring is used as it is safe and nontoxic which makes it suitable for use in the buccal cavity.
This section analyses the sodium fluoride release rates for the polymer films as the release rates for the tapes will be discussed in a future paper. The films contained 5,8,or 10% sodium fluoride (w/w). Release rates were also measured for the coloured samples to observe whether the addition of dye had any effect on the release rate properties of the films.
I
Fig 1.l. 5% NaF film weekly release
Fig 1.2. 5% NaF coloured film weekly release
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Fig 1.3. 8% NaF weekly release
..*..
II .” ., .” ..,.,
....I.
1.
I
1.4. 10% NaF weekly release
5% Noncoloured (Fig 1.1)
The samples placed in deionised water (control) release more sodium fluoride in the first two weeks than the solutions containing buffer and buffer with a-amylase. This could be due to the initial swelling characteristics of the biopolymer. The samples within the deionised water display increased swelling compared to the other solutions. This is due to the buffer solution containing trace elements which contributeto a lower swelling factor than water alone. The greater the swell factor the greater the release through diffusion of the sodium fluoride. The fluoride is encapsulated within the polymer matrix and releases initially through diffusion and then releases as degradation of the polymer occurs. As the polymer degrades the sodium fluoride is released. After the first two weeks the release rate fiom the films placed in the deionised water is less than those placed in the buffer solutions. This is due to the films in water reaching equilibrium and the diffusion process slows down. The films in the buffer and in buffer and a-amylase are still reaching equilibrium. The samples in the buffer and a-amylase release less sodium fluoride than the plain buffer. These results indicate that there is not enough a-amylase present in the sample to contribute to an increase in degradation time of the biopolymer. Overall the 5% non-coloured films display a constant release rate over the 5 week test period. 5% NIIIE”C O I O U (Fig ~ 1.2)
The samples placed in deionised water release a larger amount of sodium fluoride than the other solutions which reinforces the hypothesis of a higher swelling percentage 400 0 Woodhead Publishing Limited, 201 0
displayed with water compared to the buffer solutions. Overall the release rates from all the samples regardless of solution is higher than those from the non-cdoured samples. This indicates that the addition of a dye does have an effect on the release rates. The dye that was used was a food dye which contains water as it is a solution. The increase in diffusion could be explained by the addition of extra water and therefore an increase in the swelling factor and hence an increase in diffusion. The biopolymer is extremely hydrophilic and swelling experiments based on weight at this stage in the research have proved inconclusive, as a stable reading of the weights cannot be obtained even after conditioning 8% NaF non-coloured (Fig 1.3)
Regardless of solution the 8% film samples do not release as much sodium fluoride as both the coloured and non-coloured 5% films. A potential explanation for these results is that the films do not swell as much due to a higher percentage of sodium fluoride being encapsulated within the polymer matrix. If the 8% samples do not swell as much then there will be less fluoride release from diffusion compared to the 5% samples. Once the films begin to degrade then the 8% samples should begin to release a higher amount of fluoride than the 5% non-coloured films and potentially the 5% coloured
films. The samples in deionised water display similar results to the previous graphs but the 8% NaF films placed in the buffer and a-amylase samples release a higher amount of NaF than buffer alone. This indicates that the higher the percentage of NaF the greater the effect of the a-amylase on the starch based biopolymer. 10% NaF non-coloured (Fii 1.4)
These results are similar to the 8% results in terns of the release rates varying depending on the solutions that the samples are placed in. The 10% results are higher than the 5% and the 8% samples which was to be expected as there is a higher percentage of NaF present in the polymer. Further investigation is required to establish why the 8% samples at this stage in the research are not behaving in a similar manner.
Mean YOweekly release rate
I-.
!=
+_.
E l
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m
-I
81
. l i .
-I
-u
Fig 2.2. Mean % weekly release rate buffer
I 7---
m
I > I . U
I
I ,
-t-
Fig 2.3. Mean % weekly release rate a-amylase The deionised water (Fig 2.1) and the buffer (Fig 2.2) graphs illustrate that the 5% NaF coloured samples release the largest amount of NaF throughout the 5 week test period. The 10% samples release the second largest amounts which was to be expected. It was hypothesised that the higher the percentage of NaF encapsulated then the higher the release rate. The buffer and a-amylase (Fig 2.3)results indicate that the a-amylase only has an effect on the release rate when the percentage of NaF encapsulated within the polymer matrix is increased. The results are higher for the 8% and 10% samples.
CONCLUSIONS The device can be made into any of the design possibilities previously discussed in order to suit individual patients and their treatment options. Depending upon the patient's age and dental health, different percentages of sodium fluoride can be encapsulated within the polymer matrix in order to provide efficient treatment / prevention of dental caries. The option to have the device coloured or clear allows for patient involvement in the device by giving them a choice of having the device discreet or selecting one that is their favourite colour and having it visible. The film samples were 1 cm2 which would be too large for placement in the buccal cavity. The samples were 1 cm2in order to be within the detectable range of the fluoride ion selective electrode. The amount that was released in the 6rst two weeks was higher than the recommended daily amount of fluoride. This could be overcome by 402 0 Woodhead Publishing Limited, 2010
reducing the size of the films so that they would be a more suitable size within the paediatric buccal cavity and the release rate would be at the recommended efficient level for remineralisation and also below toxicity levels. The films do not completely degrade within the 5 week test period unlike the tapes which have complete degradation within five weeks. This offers scope for the films to be used as a release device for longer than five weeks. This could be beneficial to patients who require a longer treatment period. The films could release fluoride until complete degradation occurs or they could be removed once the recommended treatment has been completed if necessary. This paper concludes by suggesting that this novel biopolymer at this stage of research displays great potential as a slow-release biodegradable device for the prevention of paediatric dental caries. The amount of drug loading can be easily varied to suit treatment requirements and the design flexibility allows for the most suitable option to be selected in terms of comfort and acceptability.
ACKNOWLEDGEMENTS The authors would like to thank Dundee Dental School for their collaboration with this project and Scottish Enterprise Proof of Concept Programme for their sponsorship.
REFERENCES 1 M Triller, ‘Fluoride as preventative agent of caries: mechanisms, sources, risk’, Archives de Pediufrie, 1998 5(10) 1149-1152. 2 D Browne, H Whelton, O’Mullane: ‘Fluoridemetabolism and fluorosis’ Journal of Dentistry, 2005 33(3) 177-186.
3 B Peretz, G Gluck, ‘%Journal of Clinical Paediatric Dentistry’, 2006 3 191-194. 4 K J Toumba, M E J CLUZO~, ‘A clinical trial of a slow-releasingfluoride device in children’, Caries Research, 2005 39 195-200. 5 D B Mirth, ‘The use of controlled and sustained release devices in dentistry: A review of applications for the control of dental caries’, Pharmacol Ther Dent, 1980 5
59-67.
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MATERNITY SUPPORT GARMENT FOR THE RELIEF OF LOWER BACK PAJN S Ho, W Yu,T Lao, D Chow, J Chung, Y Li Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Kowloon, Hong Kong. ABSTRACT Universally, 50-70% pregnant women have experienced lower back pain (LBP). The pain can interfere with work, daily activities and sleep. Among various pain relief interventions, support garment such as the belthinder is a common part of the treatment for LBP during pregnancy. However the effect of garment treatment on pain relief is inconclusive due to limited research evidence. Moreover, little studies have examined the design principles for the development of maternity support garments. This medical device has the potential to offer a safe, low cost, and easily accessible biomechanical solution for pregnant women with LBP. The researchers hypothesize that the mechanical properties in these garments can redistribute the fetal weight to diminish the spinal loading. This research project aims to establish design principles for the development of maternity support garment, and to evaluate the effect of a prototype garment in the relief of LBP during pregnancy. The research was conducted in three phases: Exploratory Phase, Developmental Phase, and Experimental Phase. The Exploratory Phase consisted of three parts: (1) A wearing trial to determine the factors that influence wearer's acceptability through evaluation of commercially-available maternity support garments; (2) A semi-structured interview to explore the psychological needs of pregnant women with LBP, their attitudes and expectations towards the use of support garment; and (3) A biomechanical study to measure the anthropometric changes during pregnancy. In the Developmental Phase, a prototype garment was developed based on the new knowledge of psychological considerations and biomechanical model. In the Experimental Phase, a clinical trial was conducted to evaluate the effect of the prototype garment. The research deliverables not only improve back pain and quality of life, but will also impact on the fbture design of support garments.
INTRODUCTION While lifetime prevalence of lower back pain (LBP) in the general population is 60%90% in developed countries', LBP is one of the commonest musculoskeletal problems
during pregnant#. Prospective studies with moderately large samples showed that 50%-70% of pregnant women have experienced some form of LBP and that in some of these patients pain becomes chronic or recurrent3". Of those who are affected by LBP, symptoms can range from mild (45%) to severe pain (25%-33%), and some become severely disabled 8%) because of the pain7s8.The pain often interferes with work 9-12, (3daily activities 639s1 16, and The National Institute for Occupational Safety and Health (NIOSH) has conservatively estimated the annual cost due to LBP in the general population to be $13 billion18. A wide range of interventions are available for the treatment of LBP during pregnancy which include avoiding certain physical activities (climbing stairs, standing/walking for long periods), brief rests, low-heeled shoes, heat application, the use of Ozzlo pillow (a wedge-shaped pillow to fit under the woman's abdomen), 404 0 Woodhead Publishing Limited, 201 0
exercise and/or education on ergonomics, pelvic belt support, physiotherapy, water gymnastics, pain medication, acupuncture, massage, relaxation, yoga, and chiropractic treatmene”9’ ’. Among the variety of treatments under investigation, the use of a pelvic belt or su ort is a common part of therapy for back pain associated with pregnan~#’~’-~~. The underlying theory of a pelvic belt or support is that the device compresses or ‘self-braces’ the articular surfaces of the sacroiliacjoint (SIJ) to stabilise the SIJ in order to prevent the bones from moving away or against each the?^*^*. Recent studies showed that the application of a pelvic belt or suppod significantly decreased the sagittal rotation in the SIJ, and the SLT laxity and mobility in healthy women and in women with pregnancy related pelvic girdle pain (PPP) when the belt was worn in a high position oust below the anterior superior iliac The effect of pelvic belt wearing seemed to be in line with the biomechanical prediction^^^. While some studies have re orted significant pain reduction with pelvic belt in combination ! 35,-others have found no significant difference in pain score or with other thera iesZ8. activity ability ‘*36. Thus, the effect of wearing a belt on pain relief is inconclusive and needs further investigation. Furthermore, garment treatment often involves active patient participation and compliance, which will impact largely on the treatment effect41. Some studies have examined the patient satisfaction and compliance with garment treatment among bums and elderly patients424’, however studies on maternity support garments are lacking in the research literature. It is important to investigate among pregnant women as they have different physical and psychosocial needs. Although the growing research interest in LBP associated with pregnancy and its treatment only began in the 198Os, the practice of wearing maternity support garments for back pain relief is a tradition that dates as far back as the 1 2 century48. ~ Pregnant women still seem to wear maternity support garments in Western and Asian countries. This is perhaps reflected by numerous patents that are found in a broad database search includin 32 patents from the United state^^%^', 19 from Japannp8*,and 15 from Europe’ $.‘02. These commercially-available maternity support garments can be categorised into 4 major types including briefs, belt, cradle, and torso support (Table 1).
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Table 1. Types of maternity support garments Type Briefs
Front and Back views
1
Belt
Cradle
Torso support
“Briefs” refer to a garment covering the wearer’s abdomen and hip with both the waist and leg openings. Maternity briefi usually have a relatively rigid front panel to encircle the lower portion of the abdomen for support. The extensions of the abdominal panel are secured by fasteners at both sides of the upper hip with adjustable tension. “Belt” is a wide panel being worn around the Waist with the front panel supporting the lower abdomen. It is usually designed to fasten at the back or intersect at the low back and extend to the fronthide for fastening. “Cradle” contains mainly straps and bands which are worn over the shoulders of the wearer to assist the abdomen band in supporting the growing abdomen by redistributing the uterine weight to the shoulders and across the torso. “Torso support” is a vest-like garment that covers the upper torso with a belly panel of soft extensible fabric and a rigid abdominal support panel at the lower waist. While these maternity sugort qarment have been claimed to support the wearer)s abdomen and back49-57,59.67s73 88% 00-103, reduce fatigue, pressure, stress, and 51,56.59.62,63,75,76.89.93 back ,,in back ~ain49.50,U.58,59.61~,~,79,9293,grevent and/or and correct or improve posture 863*64, there is little scientific research to substantia; these claims. Only two studies have examined the effect of maternity support garments (Mother-to-be maternity support and Loving comfort back support) on back pain2991w.
STUDY AIMS Taken together, it is essential that functional garments be developed according to specific standards of requirement based on scientific evidence to ensure effectiveness and compliance with garment treatment. This research project aimed to identify design and material selection principles to guide the development of future maternity support 406 0 Woodhead Publishing Limited, 2010
garments, and to evaluate the effect of a prototype garment in the relief of LBP during pregnancy. The research was conducted in three phases: Exploratory Phase, Developmental Phase, and Experimental Phase. The Exploratory Phase consisted of three studies: (1) A wearing trial to investigate the factors that influence wearer’s acceptability through evaluation of commercially-available maternity support garments; (2) A semi-structured interview to explore the psychological needs of pregnant women with LBP, their attitudes and expectations towards the use of support garment; and (3) A biomechanical study to measure the anthropometricchanges during pregnancy. In the DevelopmentalPhase, a prototype garment is developed based on the new knowledge of acceptability criteria, psychological considerations and biomechanical concept. In the Experimental Phase, a clinical trial was conducted to evaluate the effect of the prototype garment.
STUDY OBJECTIVES 1. 2. 3. 4.
5.
6.
To investigate the psychological needs of pregnant women who are affected by LBP in terms of physical comfort, aesthetic concerns, and usability. To analyse the changes of women’s abdominal size, spinal curve, and centre of gravity during pregnancy. To determine the necessary biomechanical support for the lumbar spine of pregnant women provided by the use of support garment. To develop the design and material selection criteria for the production of maternity support garments to distribute the weight of abdomen effectively with sensational comfort and aesthetic concerns. To evaluate the acceptance of the support prototype garment by test trials. To evaluate the effect and health outcome of prototype garment for the treatment of LBP during pregnancy by using clinical trials.
SUMMARY The research deliverable is aimed not only to improve back pain and quality of life, but also to contribute towards to the future design of maternity support garments. These aspects are covered in full in the references. REFERENCES 1 G A Malanga, S F Nadler and T Agesen, Epidemiology in low back pain handbook: A guide for the practicing clinician, A J Cole and S A Herring (ed),Philadelphia, Hanely & Belfus, 2002,405-412 2003. 2 J D Heckman and R Sassard, ‘Musculoskeletal considerations in pregnancy’ JBone Joint Surg Am, 1994 76 1720-1730.
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8 €1 C Ostgaard, E Roos-Hansson and G Zetherstrom, ‘Regression of back and posterior pelvic pain after pregnancy’, Spine, 1996 21 2777-2780. 9 A Hausen, D V Jensen, M Wormsley, H Minck, S Johansen, E C Larsen, C WilkenJensen, M Davidsen and T M Hansen, ‘Symptom-giving pelvic girdle relaxation in pregnancy. 11: Symptoms and clinical signs’, Acta Obstetricia et Gynecologica Scandinu, 1999 78 111-115. 10 E C Larsen, C Wilken-Jensen, A Hansen, D V Jensen, S Johansen, H Minck, M Wormsley, M Davidsen and T M Hansen, ‘Symptom-giving pelvic girdle relaxation in pregnancy. I: Prevalence and risk factors’ Acta Obstetricia et Gynecologica Scandim, 1999 78 105-110. 11 I M Mogren, ‘Perceived health, sick leave, psychosocial situation, and sexual life in women with low back-pain and pelvic pain during pregnancy’, Acta Obstehicia et GynecologicaScandinavica, 2006 85 647-656. 12 A Sydsjo, G Sydsjo and K Alexanderson, ‘Influence of pregnancy-related diagnoses on sick-leave in women aged 16-44’, Journal of Women’s Health and Gender-based Medicine, 2001 10 707-714.
13 P Kristiansson, K Svardsudd and B von Schoultz, ‘Back pain during pregnancy: a prospective study’, Spine, 1996 21 702-709. 14 H C Ostgaard, G B Andersson and K Karlsson, ‘Prevalence of back pain in pregnancy’, Spine, 1991 16 549-552. 15 L Noren, S Ostgaard, G Johansson and H C Ostgaard, ‘Lumbar back and posterior pelvic pain during pregnancy: a 3-year follow-up’, European Spine Journal, 2002 11 267-271. 16 A Hansen, D V Jensen, M Wormsley, H Minck, S Johansen, E C Larsen, C WilkenJensen, M Davidsen and T M Hansen, ‘Pregnancy associated pelvic pain. 11: Symptoms and clinical findings’, Ugeskr Laeger, 2000 162 48 13-48 17. 17 A Fast and G Hertz, ‘Nocturnal low back pain in pregnancy: polysomnographic correlates’, America1 Journal of Reproductive Immunology, 1992 28 25 1-253. 408 0 Woodhead Publishing Limited, 2010
18 National Institute of Occupational Safety and Health,‘Workplace use of back belts: Review and recommendations’, US. Department of Health and Human Services, Public Health Service, Centersfor Diseme control and Prevention 1994. 19 J Perkins, R L Hammer and P V Loubert, ‘Identification and management of pregnancy-related low back pain’, JNurse Midwifery, 1998 43 331-340. 20 J R Richie, ‘Orthopedic considerations during pregnancy’, Clin Obstet Gynecol, 2003 46 456-466. 21 B M Busanich and S D Verscheure, ‘Does McKenzie therapy improve outcomes for back pain?’, JAthl Train, 2006 4 1 117-119. 22 A Garshasbi and Z S Faghih, ‘The effect of exercise on the intensity of low back pain in pregnant women’, Int JGynaecol Obstet, 2005 88 271-275. 23 B Stuge, G Hilde and N Vollestad, ‘Physical therapy for pregnancy-relatedlow back and pelvic pain: a systematic review’, Acta Obstet Gynecol Scan4 2003 82 983-990. 24 M Kihlstrand, B Stenman, S Nilsson and 0 Axelsson, ‘Water-gymnasticsreduced the intensity of bacMow back pain in pregnant women’, Acta Obstet Gynecol Scand, 1999 78 180-185. 25 G Young and D Jewell, ‘Jnterventionsfor preventing and treating pelvic and back pain in pregnancy’, Cochrane Database Syst Rev, 2002 CDOOll39. 26 A J Lisi, ‘Chiropractic spinal manipulation for low back pain of p r e w c y : A retrospective case series’, JMidwifry Womens Health, 2006 51 e7-10. 27 B S Banerud, M Helmert and L Larun, ‘Pelvic relaxation and physiotherapy prevention and treatment’, Tidsskr Nor Laegeforen, 1992 112 349-351.
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28 H C Ostgaard, G Zetherstrom, E Roos-Hansson and B Svanberg, ‘Reduction of back and posterior pelvic pain in pregnancy’, Spine 1994 19 894-900. 29 C A Carr, ‘Use of maternity support binder for relief of pregnancy-related back pain’, J of Obstet, Gynecologic, andNeonatal Nursing, 2003 32 495-502. 30 S M Wang, P Dezinno, L Fermo, K William, A A Caldwell-Andrews, F Bravemen and Z N Kain, ‘Complementary and alternative medicine for low-back pain in pregnancy: a cross-sectional survey’, JAltern ComplementMed, 2005 11 459-464. 31 L Noren, S Ostgaard, T F Nielsen and H C Ostgaard, ‘Reduction of sick leave for lumbar back and posterior pelvic pain in pregnancy’, Spine, 1997 22 2157-2160. 32 J M Mens, C J Snijders and H J Stam, ‘Diagonal trunk muscle exercises in peripamun pelvic pain: a randomized clinical trial’, Physical Theram, 2000 80 11641173.
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33 K Wedenberg, B Moen and A Norling, ‘A prospective randomized study comparing acupuncture with physiotherapy for low-back and pelvic pain in pregnancy’, Acta Obstetricia et GynecologicaScandina, 2000 79 33 1-335.
~ 34 N Kvorning, C Holmberg, L Gxtnnert, A Aberg and J Akeson, ‘ A c u p u n relieves pelvic and low-back pain in late pregnancy’, Acta Obstetricia et Gynecologica Scandina, 2004 03 246-250. 35 H Elden, L Ladfors, M F Olsen, H C Ostgaard and H Hagberg, ‘Effects of acupuncture and stabilizing exercises as adjunct to standard treatment in pregnant women with pelvic girdle pain: randomized single blind controlled trial’, British Med Journal, 2005 330 761. 36 L Nilsson-Wikmar, K Holm, R Oijerstedt and K Harms-Ringdahl, ‘Effect of three different physical therapy treatments on pain and activity in pregnant women with pelvic girdle pain: a randomized clinical trial with 3, 6, and 12 months follow-up postpartum’, Spine, 2005 30 850-856. 37 A Vleeming, H M Buyruk, R Stoeckart, S Karamursel and C J Snijders, ‘An
integrated therapy for peripartum pelvic instability: A study of the biomechauical effects of pelvic belts’, Am JObstet Gynecol, 1992 166 1243-1247. 38 A Vleeming, H M Buyruk, R Stoeckart, S Karamursel and C J Snijders, ‘Towards an
integrated therapy for peripartum pelvic instability’, Amerian J of Obstet and Gynecol, 1992 166 1243-1247. 39 J M Mens, L Damen, C J Snijders and H J Stam,‘The mechanical effect of a pelvic belt in patients with pregnancy-related pelvic pain’, Clinical Biomechanics, 2006 21 122-127. 40 L Damen, C W Spoor, C J Snijders and H J Stam, ‘Does a pelvic belt influence sacroiliacjoint laxity?,’ Clinical Biomechanics, 2002 17 495498. 41 L O’Hare, ‘Scholl compression hosiery in the management of venous disorders’, Br JNws, 1997 6 391-394. 42 J Johnson, B Greenspan, D Gorga, W Nagler and C Goodwin, ‘Compliance with pressure garment use in bum rehabilitation’, JBurn Care Rehabil, 1994 15 180-188. 43 L Macintyre, M Baird, P J Weedall and C Hassall, ‘Elastic fabrics for the treatment of hypertrophic scars-comfort and colour’, Technology Textiles International, 1999 8 19-22.
44 A H Myers, J D Michelson, N M Van, Q Cox and R Jinnah, ‘Prevention of hip hctures in the elderly: receptivity to protective garments’,Arch Gerontol Geriutr, 1995 21 179-189. 45 R Stewart, A M Bhagwanjee, Y Mbakaza and T Binase, ‘Pressure garment
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46 F Williams, D Jhapp and M Wallen, ‘Comparison of the characteristics and features of pressure garments used in the management of burn scars’, Burns, 1998 24 329-335. 47 C P J Chan, The product development of the maternity clothes for the Hong Kong pregnant women in the period fiom 3rd trimester to postpartum, The Hong Kong Polytechnic University, HKSAR, China, Master’s Thesis 2000. 48 H A Weber, F W Budd Jr, and J P Curlin, “Iwata Obi’ Japanese maternity lumbosacral support’, Military Medicine, 1972 137 359-360. 49 P B Rocker, Combination maternity back support and garter suspender, USPTO Patent Full Text and Image Database, US Patent No 3 384 092,1968.
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60 N C Moyer, Maternity exercise garment, USPTO Patent Full Text and Image Database, US Patent No 4 746 318,1988. 61 V L Nobbs, Maternity support undergarments, USPTO Patent Full Text and Image Database, US Patent No 5 2 17 403,1993.
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62 C L Seering, Prenatal cradle, USPTO Patent Full Text and Image Database, US Patent No 5 702 286,1997. 63 C L Seering, Prenatal girdle, USPTO Patent Full Text and Image Database, US Patent No 4 836 824,1989. 64 L L Turner, Torso support for pregnant women, USPTO Patent Full Text and Image Database, US Patent No 5 094 648,1992. 65 L R Walker, Abdominal support garment, USPTO Patent Full Text and Image Database, US Patent No 5 492 496,1996. 66 B White, Maternity garment with two-position support band, USPTO Patent Full Text and Image Database, US Patent No 4 976 653,1990. 67 S A Wimmer, Undergarment having brassiere and abdominal support sections, USPTO Patent Full Text and Image Database, US Patent No 4 822 317,1989. 68 E Guilani, R Guilani and R Guilani, Maternity support garment, US Patent and Trademark office, US Patent No 6 620 026,2003. 69 R Jackson, Maternity undergarment and method of use, USPTO Patent Full Text and Image Database, US Patent No 5 983 404,1999. 70 A Smilovic, ‘Maternity undergarment’, Maternity undergarment, 2004. 71 T R Wicks, Maternity garment, US Patent No 5 928 059,1999. 72 T R Wicks, Betterbinder abdominal binder, USPTO Patent Full Text and Image Database, Pub No US 2005/0014451 Al, 2005. 73 H Goshi, Maternity panty hose, JPO Industry Property Database, Publication No 09078306,1997. 74 M Hayashi, Belt for pregnant woman, JPO Industry Property Database, Publication NO01-148802,1989. 75 Y Ikehara, Supporter for pregnant woman or multiparow woman, JPO Industry Property Database, Publication No 2005-042225,2005.
76 M Ikeo, Belt for pregnant woman, JPO Industry Property Database, Publication No 08-089521,1996. 77 K Imai, Maternity belt for pregnant woman, JPO Industry Property Database, Publication No 2002-0885 18,2002. 78 H Ishilcawa, Maternity panties, JPO Industry Property Database, Publication No 2004-143600,2004. 79 K Kasai, Garment used for lower half body of pregnant woman, JPO I n d w Property Database, Publication No 2005-036375,2005. 412 0 Woodhead Publishing Limited, 2010
80 M Matsuki, Maternity belt for pregnant woman, JPO Industry Property Database, Publication No 2004-300642,2004. 81 Y Mototani, Maternity corset, P O Industry Property Database, Patent No 3554931, 2003. 82 A Shinozaki, Maternity belt for pregnant women, JPO Industry Property Database, Publication No 2004-300641,2004. 83 M Yorihji, Shorts for pregnant woman, JPO Industry Property Database, Publication NO 09-003702,1997. 84 K Iwasaki, Maternity garment and maternity supporter, P O Industry Property Database, Publication No 2003-082504,2003. 85 M Ogawa, Girdle or pants for pregnant woman before childbirth, P O Industry Property Database, PublicationNo 2002-317308,2002. 86 T Sekiya, Girdle provided with belt, JPO Industry Property Database, Publication No 07-258903, 1995. 87 Y Tamura, Obstetrical binder with belt, JPO Industry Property Database, Publication NO 10-266002,1998. 88 K Yanagihara, Underwear supporting belly in pregnancy hanging from shoulders, JPO Industry Property Database, Patent No 3648726,2002. 89 G Alberts, Maternity brace, EPO Europe’s Network of Patent Databases, International PublicationNo WO 021034 175A3,2002. 90 S S Alberts, Improvements in or relating to maternity girdles, pantie girdles and like supporting garments, EPO Europe’s Network of Patent Databases, Patent No GB932 740,1963. 91 S N Ari, Maternity support, EPO Europe’s Network of Patent Databases, Patent No M X P A03 000 111,2005. 92 S Y Chin, An abdominal and lower back support device for a pregnant woman, EPO Europe’s Network of Patent Databases, Patent No. GB 2 260 270A, 1993. 93 C K Hale, Maternity braces, EPO Europe’s Network of Patent Databases, Patent No GB 2336290,1999.
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94 W H Hall, Maternity garments, EPO Europe’s Network of Patent Databases, Patent No, GB1303729,1973. 95 E Haslam, Improvements in or relating to maternity belts, European Patent Office, Worldwide database, GB153731,1920.
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96 M L Jacks, Improved corsets, EPO Europe’sNetwork of Patent Databases, Patent No GB501070,1939. 97 S A Jenyns, Improvements in corsets, EPO Europe’s Network of Patent Databases, Patent No GB316902,1929. 98 M Parker, A new improved maternity belt or support, EPO Europe’s Network of Patent Databases, Patent No GB300669,1928. 99 C M Peirson, An improved corset or the like garment, EPO Europe’s Network of Patent Databases, Patent No GB643607, 1950. 100 L A Robertson, Improvements in and connected with corsets, EPO Europe’s Network of Patent Databases, Patent No GB155079,1920.
101 L G Sandford, Improvements in and relating to maternity or surgical corset, or belts, EPO Europe’s Network of Patent Databases, Patent No GB644769,1950. 102 M M Scheinberg, Foundation garment, EPO Europe’s Network of Patent Databases, Patent No GB859534,1961. 103 A Silvain, Improvements in orthopaedic corsets or girdles, EPO Europe.’s Network of Patent Databases, Patent No GB608809,1948. 104 C M Beaty, V J Bhaktaram, W F Raybum, M J Parker, H D Christensen and K Chandrasekaran, ‘Low backache during pregnancy. Acute hemodynamic effects of a lumbar support’, Journal of Reproductive Medicine, 1999 44 1007-1011.
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FOR VIBRATION SUPPRESSION L. M. Swallow, E. Siores, D. Dodds and J. K. Luo Institute for Materials Research and Innovation, The University of Bolton, Bolton, UK
ABSTRACT
This paper presents a non-invasive, self-powered system that can be used in the suppression of vibrations medically affecting people. Mechanical vibratory signals are picked up by piezoelectric sensors. Magnitude and frequency information is given as a voltage. Electronic circuitry filters, amplifies and gates the signal before either storing or manipulating and feeding the signal back to piezoelectric actuators, at the required phase and amplitude to suppress the vibrations. Outcomes of the paper show the use of different flexible piezoelectric materials to effectively increase energy storage and reduce vibrations. Advances in low power electronics have provided a means of solely powering devices kom piezoelectric harvested energy, especially with the advent of piezoelectric ceramic fibre composites. Energy harvesting has been implemented in hand cranked radios, shake powered flashlights, wind farms, and solar energy. Through the use of standard electronic techniques acquired power can be converted, stored and regulated. Piezoelectric fibre composites are capable of extracting energy from mechanical forces with the aim of collecting a portion of the mechanical energy associated with normal activates and utilising this in the creation of a self powered device to suppress low level vibrations.
Key Words: Piezoelectricity, energy harvesting, vibration suppression, piezoelectric fibre composites, wearable INTRODUCl'ION
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An overview of a patented device used in the suppression of tremors is presented. The device contains a means of detecting the tremors and means of counteracting the detected tremors. Both sensing and actuating mechanisms are piezoelectric materials, with the ability to generate a charge in response to mechanical stress and conversely to strain when subjected to an externally applied charge. Piezoelectric materials are incorporated into glove structures, in addition to sensing and suppressing vibrations, the materials can harvest a portion of the mechanical energy associated with normal hand movement. Parkinson's disease Tremors of body parts are caused due to illness in particular Parkinson's disease, Present medical solutions to reduce the symptoms are prescription medicine and surgery, the latter now less common due to the discovery of Levodopa, and only used
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for people with advanced stages of the disease for whom drug taking is no longer sufiicient Parkinson’s disease is a fairly common movement disease effecting both men and women, and is more common in older persons. It is prevalent in approximately 150 out of 100,000 people. Parkinson’s disease progresses slowly, but eventually most basic and daily routines are affected. The cause is unknown with the disease affecting the substantia nigra, a critical area of the brain controlling movement and coordination,,as well as other nearby brain structures such as the nigrostriatal pathways and the locus coeruleus. Symptoms of Parkinson’s disease are tremors, an increased tone and tension in the limbs, along with reduced and slower movement. The mentioned symptoms are the cardinal ones; however, a number of other features can occur. In the early stages of the disease approximately 70 percent of patients experience a slight tremor in the hand or foot on one side of the body, or less commonly in the jaw and face It appears as a beating or oscillating movement, usually in the range of 4-6 Hertz (Hz) ‘. Parkinson’s tremor usually occur when a person’s muscle is relaxed, giving rise to the name “resting tremor”. This means the af€ected body parts tremble when not doing work, usually subsiding when the person begins action. As the disease progresses tremors can spread to other sides of the body, however remain prominent on the original side of occurrence. It is believed that a tremor will be developed in most patients at some point in the illness. In addition to Levodopa and other anti Parkinson drugs, brain stimulationtechniques using mild electrical pulses are available to suppress resting tremor. Electrodes are implanted in the area of the brain whm nerve impulses are relayed and movement generated. Wires flow under the patient’s skin to a small generator implanted in the chest. When activated by the patient the generator blocks brain signals that trigger tremors. Since surgical procedures can destroy portions of the brain affecting movement, negative side effects concerning balance and coordination may be experienced. A technique based on a tuned vibration absorber (TVA) has been proposed 5, for the suppression of tremor associated with Parkinson’s disease. The TVA consisted of three parts, absorber mass, tuning structure, and body; presenting problems associated with the aesthetic nature of the device for the bearer.
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Piezoelectricity Jacques and Pierre Curie discovered the phenomenon of piezoelectricity in 1880, a category of smart materials that exhibit unique and interrelated properties. Application of a stress to a piezoelectric crystal generates an equivalent electric charge. Conversely the application of an external voltage will induce a shape change. The converse piezoelectric effect is employed in piezoelectric actuators making possible, quartz watches, micropositioners and ultrasonic cleaners. Sensory applications on the other hand, necessitating the direct piezoelectric effect have yielded applications in microphones, sonar, and pressure transducers etc. Many materials display piezoelectric properties, some of which are naturally occurring e.g. Quartz, whilst others are engineered to display the properties, e.g. Lead zirconate titanate (PZT), Polyvinylidene fluoride (PVDF), and ferroelectricfoams.
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PIEZOELECTRIC MATERIALS Two common piezoelectric materials are polymers (polyvinylidenefluoride, PVDF) and ceramics (lead zirconate titanate, PZT). The polymer materials are soft and flexible; however have lower dielectric and piezoelectric properties than ceramics. Conventional piezoelectric ceramic materials are rigid, heavy and can only be produced in block form. Ceramic materials add additional mass and stiffness to the host structure, especially when working with flexibleAightweight materials. This and their fragile nature limit possibilities for wearable devices. Comparisons of several piezoelectric materials are presented in Table 1. Table 1 Comparison of piezoelectric materials Materials
Density Piezoelectric constant d3, (PUN) g33)(lo3 g3,
Dielectric
A1N PZT Quartz LlNb03 PVDF PVDFnrFE
3.3 7.8 2.64 4.64 1.79 1.88
4.6 380-1500 4.3 85 (29) 9-13 9-13
4.5.6.4 289-500 2.3(dll) 100 -33 -33.5
6.45 150-250 20 -28 -80
110 25 60 132 -339 -340
158 11 525 -240 -695
Ceramic fibres can be produced in the diameter range of 10-250 jim with a low cost method. When formed into composite materials they posses all the qualities of conventional ceramics (electrical, mechanical, chemical) and mitigate problems such as weight and brittleness. The piezoelectric fibre composites (PFC) consist of unidirectional aligned piezoelectric fibres in an epoxy matrix, sandwiched between two copper clad polyimide laminates, see Fig. 1. The PFCs have higher efficiency than traditional bulky piezoelectric ceramic materials, due to their large length to area ratio Typically, when in fibrous form crystalline materials have much higher strengths and the polymer shell of the PFC allow the fibres to withstand impacts and harsh environments far better than monolithic piezoelectric ceramic materials. The technique of applying interdigitated electrodes takes advantage of the greater d33 piezoelectric constant where the full electrode coverage on top and bottom of the sample makes use of the lower d3l response, again shown in Table 1. A test method and data has been reported for interdigitated electrode configurations of several line widths and spacing ratios Concluding that output strain per volt progressively increases as electrode spacing decreases (however narrowest spacing ratios are prone to voltage breakdown), with single crystal fibres again increasing the free strain actuation lo.
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POWERHARVESTING Advances in wireless technology and low power electronics enable devices to be placed anywhere. A primary feature of a wireless device is to have its own power supply, most tending to use batteries. Once the finite supply has extinguished its electrical power the device must be obtained and power supply replaced or recharged, depending on task and location this could be expensive or impractical. Power harvesting devices capture normally lost energy, utilising this can produce devices less dependent on finite energy 0 Woodhead Publishing Limited, 201 0 41 7
sources. Major sources of energy loss are environmental vibrations and motions of biological systems, these sources are ideal for piezoelectric materials. Piezoelectric materials have high energy conversion efficiency in comparison to other energy harvesting devices, namely solar cells.
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Figure 1 PiezoelectricFibre Composite
The concept of utilising piezoelectric materials for energy generation has been studied greatly over past decades. Hausler proposed an implantable physiological power supply using PVDF films. Umeda et al. l2 looked at using impact energy from a steel ball dropped onto a plate with piezoelectric material attached to its underside. Elvin et al. l 3 theoretically and experimentally investigated the use of self powered PVDF strain sensors. One ambient vibration source is human movement; Starner l 4 explored the possibility of eliminating bulky and inconvenient power supplies by acquiring energy exhausted in everyday activities, such as: breathing, blood pressure, and waking, to power portable electronic devices. Calculating tha! approximately 60-70W of power is lost during walking and using a piezoelectric material in a shoe with a conversion efficiency of 12.5%; 8.4W of power could be produced. Intelligent clothing with flexible piezoelectric materials integrated into fabrics, may be capable of collecting a portion of the mechanical energy associated with everyday activities. With the converted electrical energy used to charge portable devices fiom MP3 players to medical monitory systems. Wearable devices will undoubtedly multiply in years to come due to a constant decrease in size and power requirements of electronic systems. Batteries will therefore present numerous problems, mainly their bulky size and the fact that they need to be periodically replaced or recharged. Piezoelectric materials respond to almost any type and magnitude of physical stimulus, including but not limited to pressure, tensile force, and torsion. One wearable ap lication embedded a piezoelectric material into a shoe to generate power form walking P 5. VIBRATION SUPPRESSION Head Sport AG of Austria has built an entire Intelligence0 protect line based on PFCs. Skis with a combinationof power conversion and control electronics are able to actively control torsional stability, without the aid of an external power source. PFC within the h e of the Head Intelligence0 and Protectom tennis racket can actively control vibrations resulting h m ball strike, leading to a racket that can reduce the effects of tennis elbow 16. Mechanical energy of a ball impact is converted to electrical energy of high potential and low current. This is electrically conducted to and stored in a coil in a circuit and released back to the PFCs, in real time, optimal phase and waveform for most effective damping, again independent of an external power source. Additional 41 8 0 Woodhead Publishing Limited, 2010
applications are found in smart and vibration free baseball bats, balance correcting golf equipment, self powered in-vivo medical devices (breath and pulse powered), smart hockey sticks, vibration reduction devices in wind turbines and self powered tyre pressure sensors. On an increased scale with respect to force are smart automobile suspension systems.
DEVICE OVERVIEW The proposed device incorporates piezoelectric materials into glove structures worn by suffers of Parkinson’s disease, hand tremors are sensed by the PFC materials through the direct piezoelectric effect, thus producing a representative amplitude and frequency waveform. Gating circuitry is used to monitor the waveform, distinguishing whether the movement is a normal body function or tremor. The gate result allows the generated charge to be collected and stored or fed back via control and amplification circuitry to a second tandem piezoelectric material to actuate at the relevant phase and fkquency to suppress tremors. If the generated charge is not of an amplitude and frequency to suggest resting tremor, the signal is rectified in order to remove the negative portion of the waveform and fed to a storage capacitor or relevant medium where it can be accumulated. Only when the control and amplification circuitry requires activation, the storage medium releases charge via a regulator. When the piezoelectric generated charge is of amplitude and frequency to suggest resting tremor, suppression circuitry is activated. The signal is in real time inverted and amplified before being fed back a second PFC to actuate, inducing a force on the glove to suppress the vibratory signal. For a block diagram of system operation see Fig. 2. Initial tests are to be conducting using single tandem materials for the suppression of constant fiequency sinusoidal signals, after verification of material and circuitry different PFC placements will be investigated for the ability of suppressing multidirectionalmovement, see Fig 3. Piezoelectric Material
7
4
Tremor
Gating Circuitry
4
1L
Control Circuitry
4
Power Amplifier
Normal BdY
1L
Regulated Supply
Movement
7 Rectification
+
Charge Storage
Regulation --.)
Figure 2 Vibration suppression and energy harvesting circuit block diagram
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c
Figure 3 Examples of PFC placement in glove structures
RESULTS Results have been present comparing flexible piezoelectricmaterial materials for energy harvesting applications 17. Figure 4 shows the response of the PFC and a piezoelectric polymer at different excitation kquencies. Distinct beam resonances are displayed; .however, most noticeable is the fact the PFCs produce approximately five times the voltage in comparison to polymer materials. The graphs of Fig. 5 show that bmorph materials increase the charge generated, however the metal centre reduces the overall flexibility of the composite, limiting integration into wearable devices. The second plot of Figure 5 gives a comparison of PFC fibre diameter, indicating larger fibre diameters yield greater charge generation. 260u PFC
LOT4 1
46
0 76
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E
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B
4 I5
ow
026
0
0
0
10
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M
M
0
10
Frequmsy ( H r )
44
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w
loo
M
loo
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Figure 4 Comparison of flexible piezoelectricmaterials Flbre 018m.ur Comparison
ZIOu MulUIayar Comparison '1
4s
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b
30
9 l 6
0 0
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44
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Figure 5 Comparison of PFC multilayer stacks and fibre diameter 420 0 Woodhead Publishing Limited, 2010
DISCUSSION Literature suggests that ceramic materials have the greater piezoelectric properties, however for incorporation into wearable devices, it is required that the materials have a textile nature. Monolithic piezoelectric ceramic materials are brittle and fiagile, preventing normal body functions, PFCs have the flexibility of piezoelectric polymer materials due the to the polyimide outer layers. It can be noted fiom Figure 4 that use of the PFC can improve the amount of harvested energy. It is also envisioned that actuating experiments will yield more advantageousproperties for the PFC.
FUTURE WORK Work will be conducting in the creation of more repeatable PFC devices where parameters such as: the numbers of piezoelectric fibres, different fibre diameter, and different fibre pitch will be investigated. Power harvesting and actuating experiments are to be conducted concluding in optimum material selection.
ACKNOWLEDGEMENTS The authors would like to acknowledge the help and support of the EPSC DTA award for their backing in the project.
REFERENCES 1 E Siores, L M Swallow, ‘Detectionand suppression of muscle tremors’, Pat No GB0623905.7, November 2006. 2 S C Conley, J T Kirchner, ‘Medical and surgical treatment of parkinson’s disease: Strategies to slow symptom progression and improve quality of life’, Postgrad Med, 1999 106(2) 41-52. 3 M B Stem, ‘Parkinson’s disease: Early diagnosis and management’, J Fam Pruct, 1993 36(4) 439-446. 4 S C Conley, J T Kirchner, ‘Parkinson‘sdisease--the shaking palsy: Underlying factors, diagnostic considerations, and clinical course’, Postgrad Med, 1999 106(1) 39-52. 5 S M Hashemi, M F Golnaraghi, A E Patla, ‘Tunedvibration absorber for suppression of rest tremor in parkinson’sdisease’, Med B i d Eng Comput, 2004 42(1) 61-70.
6 R B Cass, A Khan, F Mohammadi, ‘Innovative Ceramic-Fiber Technology Energizes Advanced Cerametrics’, American Ceramic Soiciety Bulletin, 2003 9701-9706. 7 R B Williams, G Park, D J Inman, W K Wilkie, ‘An overview of composite actuators with piezoceramic fibers’, Proceedings of the 20th Int C o d Modal Analysis Conference, Los Angeles, CA, 2002. 8 F Mohammadi, A Khan, R B Cass, ‘Power generation from piezoelectric lead zirconate titanate fiber composites’, Mat Res Soc Symp Proc, 2003 736 D5.5.1-D5.5.6.
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9 R J Werlink, R G Bryant, D Manos, ‘Macro fiber piezocomposite actuator poling study’, February 2002. 10 R Gentilman, K McNeal, G Schmidt, A Pizzochero, G A Rossetti, ‘Enhancedperformance active fiber composites’, Smart Structures and Materials 2003,2003 5054 350-359.
11 E Hauler, L Stien, ‘Implantable physiological power supply with PVDF film’, Ferroelectrics, 1984 60 277-282.
12 M Umeda, K Nakamura, S Ueha, ‘Analysis of the transformation of mechanical impact energy to electric energy using piezoelectric vibrator’, Jpn J Appl Phys, 1996 35(1,5B) 3267-3273.
13 N G Elvin, A A Elvin, M Spector, ‘A self-powered mechanical strain energy sensor’, S m r t Mater Struct, 2001 lO(2) 293-299. 14 T Starner, ‘Human-powered wearable computing’, IBM Systems Journal, 1996 35(3/4) 618629.
15 J Kymissis, C Kendall, J A Paradiso, N Gershenfeld, ‘Parasitic power harvesting in shoes’, Proceedings of the 2nd B E E Int Symp on Wearable Computers, Pittsburgh, PA, IEEE Computer Society, 1998. 16 J Kotze, H Lammer, R Cottey, W Zirngible, ‘A study into the effects of active piezo fibre rackets on tennis elbow’, Report from the Institute of Orthopaedics and Sports Medicine, Munich, Germany, Mar. 2003. 17 Swallow L, Siores E, Luo J, Dodds D. ‘Comparisonof piezoelectric materials for use in energy harvesting applications’, Proceedings of the Knowledge and Innovation Conference, Bolton, In Publishing, March 2007.
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GAS PLASMA TREATMENT OF POLYPROPYLENE DENTAL TAPE J.M. Warren', R.R. Mathe2, A. Neville3 and D. Robson' 'School of Textiles and Design, Heriot-Watt University, Galashiels, Scotland TD1 3HF 2 School of Engineering and Physical Sciences,Heriot-Watt University, Edinburgh, Scotland EH14 4AS 3Schoolof Mechanical Engineering, University of Leeds, Leeds, England LS2 9JT
ABSTRACT This paper highlights how modification of the morphological and chemical characteristics of the surfaces of polypropylene (PP) by gas plasma treatments may enhance their application as dental flosses. Scanning electron microscopy (SEM) and scanning probe microscopy (SPM) have been used to observe in detail the contrasting surface effects created by different plasma gases on PP tape. The results of SEM and SPM analysis are discussed with reference to dental applications.
INTRODUCI'ION
Gas plasma treatment is not a new technology; however, it is only due to recent technical advancements that it can be used to treat materials on a commercial scale. Examples of such advancements are the introduction of large low-pressure treatment units and atmospheric plasma technology [I]. It is these advancementsthat have led to either batch treatments at low pressures or to continuous in-line treatment at atmosphericpressure. There are two main types of gas plasma treatment: low pressure and atmospheric pressure. Low pressure or vacuum gas plasma was the first method used. This consists of an enclosed system where a gas is injected into a chamber under vacuum and a high voltage is passed across two electrodes, generating the plasma. Recently atmospheric systems have been created, where the plasma is generated in ambient pressures. Both systems have advantages and disadvantages,in terms of how they can treat samples, the amount of energy / raw materials used and the types of samples that can be treated. In both cases the main benefit of the gas plasma treatment process is that the surface of the sample can be modified without damaging the samples bulk properties, in a clean and cost efficient way. Gas plasma treatments can do this because the process is surface active and is a dry process. As a result, the process uses fewer starting materials and less energy than many conventional techniques making it a much cleaner surface treatment process. A variety of work has been carried out using plasma treatments. However, it has generally been utilised as a process tool without in-depth microscopic analysis into changes in the topography of polymers at the polymer - plasma interface. Work carried out using plasma treatment includes investigations of changes in mechanical properties [2] and reactivity [3], contact angle measurements 1141, radical analysis and changes in the sub-surface chemistry [5]. In this paper, we describe the topographical differences caused as a result of plasma treatments. To andyse the gas plasma treated samples, two different types of microscopy were applied: scanning electron microscopy (SEM) and scanning probe microscopy (SPM). The SEM images were collected under vacuum, and the SPM images were obtained under ambient conditions. 0 Woodhead Publishing Limited, 201 0 423
EXPERIMENTAL PP tape production The polypropylene raw material used for this work was FINAPRO PPH 9096 from AtoFina Chemicals, with a melt flow index (MFI) of 25.0 g / 10 min as quoted by the manufacturer. Once tested the h4FI was found to be 29.0 g / 10 min. The PP tape was extruded using a bench top labspin extrusion plant for medical polymer research, model MBP 25/1 (Extrusion Systems Limited (ESL)), fitted with a single slit die with a width of 8 mm and a depth of 0.4 mm. The tape was extruded under the following conditions: barrel temperatures were 180, 185 and 190°C, respectively for the three zones. The metering pump temperature was 195OC with a speed of 4 rpm. The die head temperatures were 2OO0C for each zone, with the extruded tape subsequentlycooled in a water bath at a temperature of 26°C. The cooled tape was collected by means of a winder with a speed of 10 rpm. For the second section of the work, extrusion conditions were varied, in order to assess their effect on the plasma treatment. Three conditions were created, ranging h m gravity collection without any draw, to fully drawn where the tape was drawn on a separate drawn frame to the point at which it started to break. For producing the gravity-spun sample, the metering pump was set at 0.6 rpm. The tape was air cooled and collected by hand. For producing the partially drawn sample the metering pump was set at 4 rpm. The tape was cooled in a water bath at 38OC and was collected using the quench tank winder set at 10 rpm. For producing the l l l y drawn tape the metering pump was set at 4 rpm. The tape was cooled in a water bath at 38OC and was passed through the quench tank winder at 23 rpm. The tape was subsequently diverted onto a draw frame and cold drawn using three successive rollers, set at 30,49 and 200 rpm, respectively.
Plasma treatment procedrves The plasma treatment equipment used throughout this work was a surface treatment CD400PC M H z system laboratory scale plasma treatment plant, supplied by Europlasma. To keep the work more consistent the equipment's automated mode was used throughout the work. Consequently, an operating procedure was devised to control the plasma treatments. This option also allowed process time, power and process gas to be altered. Three treatment times of 1 , s and 10 minutes were used along with two operating powers of lOOW and 300W. The gases used were oxygen, argon and nitrogen. Two methods of sample preparation were employed, both of which utilised perforated metal trays to house the samples.
SPM procedures The SPM used throughoutthis work was a Topometrix TMX 2000 explorer supplied by TM Microscopes. The X, Y, Z scan range for the scanner head used was 100 x 100 x 8 pn. However, due to the diverse nature of the tape's topography a maximum scan range of 50 x 50 pm was generally used. Incontact mode, silicon nitride tips were used throughout, with a nominal spring constant of 0.03 Nm". All images were taken under ambient conditions and with a constant force, set at between 5 and 30 n ~ .Tape samples were prepared for scanning by mounting small sections (6-8 mm) onto steel AFM stubs using doublesided adhesive carbon discs. 424 0 Woodhead Publishing Limited, 2010
SEM procedures A Hitachi S530 scauning electron microscope was used tbroughout this work. The PP tape samples were cut into small sections (6-8 mm in length) and mounted onto steel SEM stubs using double-sided adhesive carhn tabs. Due to the insulating nature of the PP tape, the samples were gold coated for 30 seconds using a Polaron SC7620 sputter coater to avoid surface charging. Once coated the samples were viewed using accelerating voltages between 15 and 25 kV.
SURFACE CHARACTERISTICS OF PLASMA TREATED TAPE It has been observed that quite extensive morphological changes arise on the surfaces of extruded PP tape as a result of gas plasma treatments [6]. Figs l a 4 illustrate some of these morphologies. The untreated tape surface appears smooth, except for some grooves running parallel to the length of the tape (fig. la). The arrows in the figures dictate the tape direction. These grooves are thought to arise from small defects in the die slit, formed during the extrusion process used to produce the tape. Afier argon plasma treatment for 1 min at 300W, however, the tape surface is covered mainly in clusters of angular structures, which appear highly crystalline (fig. lb). These clusters appear either as individual units or merged to form larger entities. The lengths of the units are ca 1.8 pn, and the breadths are in the range, 0.7-1.8 pm. Nitrogen plasma treatment also produces angular structures over the PP tape surface (fig. lc), but the length and breadth of each structure is generally similar, in the range of 1.4-2.3 pm. It is noteworthy too that small cross-shaped structures are also observed (fig. 1d).
Fig la: SEM of untreated PP tape
Fig 1b: SEM of argon treated PP tape
Fig Ic: SEM of nitrogen treated PP tape
Fig 1d: SEM of nitrogen treated PP tape
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The most intriguing changes in the morphology of the tape surfaces are observed after oxygen gas plasma treatment, which is generally recognised as a more powerfid plasma treatment [7]. Figs 2a-c show images of the tape surface after it has been exposed to oxygen plasma for 1 min at 300W. Several types of structure can be noted. One type (fig 2a) consists of small angular formations (some assembled in small clusters) similar to those portrayed in Figs l b and lc. Other angular formations are observed, however, at the tips of small crosses in localised p u p s across the tape surface (figs 2a and 2b). The crosses extend over 10-20 pm. In still other formations, there are cross-shaped structures with multiple cross-hatching (fig 2c). The structures are generally 5-15 pm across.
Fig 2a: SEM of oxygen treated PP tape
Fig 2b: SEM of oxygen treated PP tape
Fig 2c: SEM of oxygen treated PP tape Apart from changes to the morphology of the tape surface, gas plasma treatments can also induce changes in the chemical nature of the surface. Although in this work we have not studied changes in the surface chemistry of the extruded PP tapes, there is plenty of evidence from work elsewhere on PP materials to suggest that surf= chemical modification will have occurred. In particular, oxygen plasma treatments are known to render PP fibre surfaces hydrophilic [8,9], due to the introduction of oxygencontaining functional groups at the surface. Nitrogen plasma treatments are also likely to alter the chemical character of the tape surface, through the introduction of nitrogencontaining functional groups [lo]. Changes in the way the tape is processed also affect the surface morphology. After cold drawing, the PP tape surface appears more resistant to morphological change, even after oxygen plasma treatment for as long as 5 min at 300W. Whereas gravity-pun PP tape contains spherulitic structures of the type shown in fig 3a Fig 3b reveals that the surface of the cold-drawn tape is dominated in microfibrils, with no discernible spherulites. (The scored groove running at ca. 20" to the tape axis is a defect in the tape caused during extrusion [6]). After oxygen plasma treatment of the gravity-spun tape 426 0 Woodhead Publishing Limited, 2010
for 5 min at 300W, the boundaries between the spherulites are less clear (fig 3c). Moreover, the spherulitic surfaces appear pitted. This is evident from the number of light speckles on each of the spherulites. On the other hand, treatment of the drawn tape appears to induce little change (fig 3d). The fibrillar structure is still clearly evident; only the surface is slightly roughened. As expected, the partially drawn PP tape consists of both spherulites and microfibrils. The spherulites, which possess more distorted shapes than those in the gravity-spun tape, are damaged by the oxygen plasma treatment, but the microfibrils by and large remain intact.
Fig 3a: AFM image of gravity spun PP tape
Fig 3b: AFM image of fully drawn PP tape
Fig 3c: AFM image of oxygen treated gravity spun PP tape.
Fig 3d: AFM image of oxygen treated fully drawn PP tape.
PP TAPES As DENTAL FLOSSES The primary function of a dental floss is to clean the crevices (interproximal areas) between adjacent teeth. A floss should remove not only food caught in the interproximal areas, but also encrustations of bacteria. Commercial dental flosses are often impregnated with a variety of substances. These include for example, antibacterial agents, teeth whitening agents and flavourings [ll]. When impregnated with an amine fluoride gel, a dental floss also acts as a source of fluoride for interproxcimal surfaces [12]. Indeed, numerous coating formulations exist in the patent literature. 0 Woodhead Publishing Limited, 2010 427
It is clear that, whatever the nature of the coating, its ingredients should adhere to the floss h m the time when they are incorporated into it until the time when it is used. During flossing, these ingredients should normally be released. Thus, the natuse of the surface of the floss has to be such that during its preparation, its packaging, its storage and its transportation, the coating must remain intact on the floss surface. The action of the flossing, however, must provide enough force to release the ingredients of the coating. The morphology and chemistry of the tape surfaces are, therefore, fuudamental to the successful application of a dental floss, whether it is to remove trapped food from interproximal cavities or to release the coating there. Moreover, users generally prefer a floss whose surfaces feel to them quite smooth. Our work to date demonstratesthat gas plasma treatment on PP tape can provide a range of surface morphologies. The particular morphology produced depends on the nature of the gas plasma, the duration and power of the treatment and the tape processing conditions (especially the drawing conditions). Furthermore, some gas plasma treatments, will convert the PP tape h m being hydrophobic to being hydrophilic, and so render the tape more compatible with the surfaces of the teeth and much of the unwanted material that is lodged between them. In particular, the maximum dimension of bacteria ranges h m ca 0.5 pm to 5 pm. This range is of the same order of magnitude as that of the angular and cross - shaped structures shown in figs 1 and 2, and of the spaces between adjacent structures. We, therefore, tentatively suggest that some gas plasma treatments of PP tape may enhance entrapment of bacteria, depending on the shape of the bacterial cells and the shape of the gaps between adjacent tape surface structures. The chemical nature of the plasma treated tap surface w ill also play a significantrole.
ACKNOWLEDGEMENTS The authors of this paper would like to thank the Biomedical Textile Research Centre at Heriot-Watt University for its financial support to J. M.Warren, and to Marian Millar for her assistance and technical guidance in using the SPM. The authors would also like to thank Stewart Wallace for his advice and help in the extrusion of the PP tapes and use of the plasma machine, and finally to AtoFina Chemicals for the provision of the raw PP material.
REFERENCES 1 M Lieberman and A Lichtenberg, Principles of Plasma Discharges and Materials Processing, John Wiley and Sons,New York, 1994.
2 N Inagaki, S Tasaka and M Imai, ‘Hydrophilicsurface modification of polypropylene filmsby CC4plasma’, J. Appl. Polym, Sci, 1993 48 1963.
3 F Ponan-Epaillard and B Chevet, J C BrossE, Plasma Surface Mod9cation of Polymers Relevance to Adhesion, edited by M strobel, C S Lyons and K L Mittal, VSP BV., Netherlands, 1994. 4 P Wittenbeck and A Wokaun, ‘Plasma treatment of polypropylene surfaces: Characterizationby contact-anglemeasurements’, J Appl. Polym. Sci, 1993 50 187. 428 0 Woodhead Publishing Limited, 201 0
5 A Holltinder, R Wilken and J Behnisch, Surface and Coating Technology, 116-119
(1999)788.
6 J M Warren, R R Mather, A Neville and D Robson, ‘Gas plasma treatments of polypropylenetape’,J. Mat. Sci, 2005 40 5373-5379. 7 C D Rady P Kiekens and J Verscheruren, Surface Characterisation of Fibers and Textiles, C M Pastore and P Kiekens (A), Marcel Dekker, New York, 2001,pp 203218. 8 Q F Wei, R R Mather, X Q Wang and A F Fotheringham, ‘Functional nanostructures generated by plasma enhanced modification of polypropylene fibre surfaces’, J Mat. Sci, 2005 40 5387-5392.
9 E Occhielle, M Morra, G Morini, F Garbassi and P Humphrey, ‘Oxygen - plasma treated polypropylene interfaces with air, water and epoxy resins’. Part 1. Air and water, J. Appl. Polym. Sci, 1991 42 551-559. 10 B MarcandaLli and C Riccardi, Plasma Technologies for Textiles, edited by R Shishoo (ed),Woodhead Publishing, Cambridge, 2007,282-300
1 1 J P Curtis and J H Kemp, Dental floss, Colgate Palmolive Co (New-York, NY), US Patent Office,Pat No 5 209 251,November 1993.
12 D Bohrer, Z Hirschfield and I M i a , ‘Fluoride uptake in vitro by interproximal enamel fmm dental floss impregnated with amine fluoride gel’, J. Dentistry 1983 11 271-273.
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INVESTIGATING FRACTURE MECHANISMS OF SOME NON ABSORBABLE SUTURES IN MVO A S Hockenberger and E Karaca Uludag University, Faculty of Engineering and Architacture, Department of Textile Engineering, Bursa, Turkey
ABSTRACT The change of two important mechanical properties, tensile strength and knot strength reduction and h t u r e mechanisms of four different nonabsorbable sutures, namely silk, polyester, polyamide6 and polypropylene in vivo were evaluated. Three different sizes (0,2/0,3/0) were also used for each suture type. In the experiments in vivo conditions, rats Rattus norvegicus in race obtained h m University of Uludag Medical Faculty Experimental Animals Breeding and Research Centre, have been used. The experiments were carried out before and after implantation. Effect of in vivo mnditions on tensile strenth, knot strength,knot security and fracture mechanisim were evaluated. Effect of fibrous tissue (a capsule) around the suture and knot plays an important role on both tensile and knot strength retention, knot security and fiacture mechanism. As a protein based natural material showed great deal of knot and tensile strentgth reduction as it is effected by the water absorbtion h m the body fluid. Due to fibrous tissue, however, the rate of reduction was not as high as expected. Broken ends showed no scattering of the filaments and the knot was not opend. This was not the case for braided polyester suture. No fibrous tissue was observed around the suture and the knot. The knot was opened and the filaments were scattered at the broken ends. Polyamide and Polypropylene sutures were in monofilament form. Typical ductile fracture for PA suture and typical anisotropic hcture for polypropylene suture were observed. No effect of in vivo was recorded for the both sutures in terms of fracture mechanism. However a reduction in knot and tensile strength was clear for PA suture as water efects the molecule chain due to amide linkages.
INTRODUCTION Sutures remain the most common method of approximating the divided edges of tissue (1). Sutures are categorised by size, material, design and behaviour. Absorbable and nonabsorbable materials are further divided into synthetic versus natural products, some of which can be fabricated in braided andor monofilament form. Non-absorbable sutures have played an important role in the development of surgical procedures, generally made of silk, polyamide, polyester, polypropylene, polyethylene and poly(tetrafluoroethy1ene) (2). The success of a suture is widely linked to its mechanical performance features, such as tensile strength and dimensional stability. The desirable fibre properties that a good suture material should possess include inertness, adequate tensile and knot strength and strength retention in the body’s environment, and good healing characteristics. Furthermore, the fibres must be biologically compatible with the surroundingbody tissue (3). Fracture mechanism of a textile material after it has been subjected to any load or deformation, plays an important role in determining its mechanical behaviour. Analysis of the breaking mechanism is important to determine the performance of material during 430 0 Woodhead Publishing Limited, 2010
the last usage. Physical structure of material and breaking conditions affect the breaking mechanism (4). The purpose of this study was to investigate some non-absorbable sutures' mechanical performances according to change in fracture mechanism after 3 and 8 weeks in vivo. Tensile and knot strength tests were performed to evaluate their surface changes due to biological environment and Scanning Electron Microscope (SEM) and optical light microscope analysis were carried out to observe the fiacture mechanisms.
EXPERIMENTAL Material
In this study, two most commonly used, non-absorbable sutures; namely silk and polyamide 6 (PA6) have been used in order to see the effect of in vivo conditions on the mechanical performance in terms of fracture mechanism. All sutures were assured in sterile form. Fig. 1 shows the sutures used in this study. The physical structure of sutures affects their mechanical behaviour as well as their suture size. Therefore, one type of monofilament and one type of braided sutures were chosen. Three different sizes of 0, YO and 3/0 United States Pharmacopoeia (USP) were also used for each suture type. In the experiments in vivo conditions, rats obtained from University of Uludag Medical Faculty Experimental Animals Breeding and Research Centre have been used. Turkish national regulations for the care and use of laboratory animals have been observed. The necessary permission for animal use was given by the centre (dated 02.04.2002, no:4).
Figure 1. The surface views of the sutures (0 USP) [(a) silk, (b) polyamide] Method The experiments were carried out in two stages.
Initial experiments fiefore implantation) The tensile and knot strength measurements of all sutures were carried out using an Instron 4301 Tensile Tester before implantation. Prior to tests, all sutures were conditioned in standard atmosphere conditions (20 OC and 65% relative moisture) for 24 hours. 0 Woodhead Publishing Limited, 201 0 431
In the knot strength tests, a single and simple knot (see Fig. 2) was tied in the middle of the sutures mechanically on the W o n Tensile Tester by applying 10 N tensions. During the tests, the distance between jaws of 80 mm and the gauge speed of 200 mmlmin were chosen. After all sutures were broken, a Jeol840 Scanning Electron Microscope (SEM) and an Olympus SZ6045 T r i n d a r Stereo Zoom Microscope (TSZM) were used to analyse the broken ends and the surface of the sutures.
Figure 2. Formation of a single, simple knot for knot strength test Experiments in vivo (aper implantation)
The sutures have also been prepared in two forms for in vivo experiments as in initial experiments. Then sutures were placed in the abdominal cavity of rats in straight form and with a knot in the middle (see Fig. 3). After 3 and 8 weeks the rats were euthanised and the sutures were removed h m the abdominal cavity for testing. The sutures were then tested using the Instron Tensile Tester as in the initial experimental conditions. After all sutures were broken, SEM and TSZM were used to analyse the broken ends and the d a c e changes along the sutures.
Figure 3. Implanted sutures in the abdominal cavity of a rat
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RESULTS AND DISCUSSION Fig. l a shows the surface of untreated silk suture, already containing many impurities. The filaments have no regular diameter and surface characteristics. It is also difficult to distinguish the single filaments. They seem to stick to each other and stay as bundles. Silk is derived fiom the cocoon of the silkworm (Bombyx mori). It is defined as protein fibre. Fibroin chains are believed to be nearly full-extended, highly crystalline, and almost perfectly aligned in the fibre direction, all of which contribute to the fibre’s considerable stifhess and strength.Fibrous proteins, such as silk, are characterisedby a highly repetitive primary sequence that leads to significant homogeneity in fine structure. Because of these structural properties it shows impressive mechanical properties and provides important material options in the field of controlled release, biomaterials and scaffolds for tissue engineering (5). At the broken ends of silk suture the flattening of the filaments was observed before implantation. This contributes to the presence of lateral forces on loading (see Fig. 4).
According to US Pharmacopoeia an absorbable biomaterial (suture) is defined as one that loses most of its tensile strength within 60 days post-implantation in vivo. Within this definition, silk is correctly classified as non-absorbable. However, according to literature, silk is degradable but over longer time periods due to proteolytic degradation usually mediated by a foreign body response. In general, silk fibres lose the majority of their tensile strength within one year I, and fail to be recognised within two years (2). When implanted in living tissues, suture materials inevitably elicit a wide range of tissue reactions and cellular responses. The degree of tissue reaction depends largely on the chemical nature and physical configuration of the various suture materials. Suture materials of a biological nature produce more marked tissue reactions than those of a synthetic nature, while a greater response is caused by multifilament sutures than by monofilament sutures (3). Therefore braided and protein based silk sutures of the study showed more pronounced fibrous tissue capsules in vivo (see Fig. 5a). In the knotted form, the break was always beneath the knot whilst the knot remained in place. Also, after 3 and 8 weeks in vivo, a more clear fibrous capsule was seen around the knot due to a greater quantity of suture material (see Fig. 5b). This tissue capsule form plays an important role on the fracture mechanism of silk suture post implantation. The filaments were held or glued together by this capsule. When broken ends were analysed the 0 Woodhead Publishing Limited, 201 0 433
filaments were sticking together and no scattering of broken filaments were seen, (see Fig. 6).
Figure 5. The fibrous tissue capsule of the silk sutures after implantation [(a)straight form (0 USP) (XIO); (b)knotkd form (3/0 USP)]
Figure 6. The broken ends of the silk sutures (0 USP) after tensile strength test post implantation (x10) Aliphatic polyamides are polymerised either fiom polycondensation of a dicarboxylic acid and a diamine, or through a ring-opening polymerisation of appropriate lactams. In this study monofilament polyamide with repeating unit (-NH(CH2 )sCO-) was used. Polyarnide 6 is made from caprolactam. Among the synthetic non-absorbable sutures, polyamides are probably the one most susceptible to degradation. However, due to its amide linkages on the molecular chains and hydrogen bonding between the chains, it has high tensile strength and its flexible chain structure gives excellent elastic properties. The main disadvantage of using polyamide is its prominent memory, which consequently decreases its knot security. In this study undone knots after knot strength measurements, before and after implantation, were also observed (see Fig. 7).
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Figure 7. The opened knot of polyamide suture (3/0 USP) after knot strength test Although polyamide is considered a non-absorbable suture, it still undergoes partial degradation through hydrolysis at a very slow rate due to -NHCO- groups on the polymer backbone as they are very polar and can hydrogen bond with water easily. Polyamide monofilament sutures show smooth surfaces with a circular cross-section before implantation (see Fig. 1b). No fibrous tissue capsule was observed on the suture surface or around the knot post implantation. This is contributed to its smooth surface characteristic. However a closer examination of the opened knot shows flattening of the knot region (see Fig. 7).This is attributed to the ductile structure of polyamide sutures. It shows permanent deformation due to lateral forces exerted during loading. The rupture of the melt-spun synthetic fibres like polyamide is dominated by yield. Plastic yield of material causes the crack to open into a V-notch, which propagates steadily into the specimen. This typical ductile hcture was seen at the broken ends, after tensile tests, both before and after implantation (see Fig. 8).
Figure 8. The ductile fixture mechanism of the polyamide suture (3/0 USP) after tensile
strengthCONCLUSION
This study has analysed fixture mechanisms of two non-absorbable sutures before and after 3 and 8 weeks implantation in rats. Scanning Electron Microscope (SEW and optical light microscope were used for analysis of kcture mechanisms and surface changes of the sutures. A clear in vivo effect on the hcture mechanism was seen for braided silk suture. Typical ductile fixture for polyamide suture was observed. In terms of fracture mechanism it was not affected by the implantationand the implantationtime. In the knotted form, the break was always beneath the knot and the knot was securely in place for silk suture. In polyamide suture, undone knots were observed. While silk 0 Woodhead Publishing Limited, 201 0 435
sutures showed pronounced fibrous tissue capsules in vivo, no fibrous tissue capsule was observed for polyamide sutures.
REFERENCES 1 C A Zimmer, J G Thacker, D M Powell, K T Bellian, D G Becker, G T Rodeheaver, R F Edlich, ‘Influence of knot configuration and tying technique on the mechanical performance of sutures’, JEmerg Me4 1991 9 107-113. 2 D Greenwald, S Shmway, P Albear, L Gottlieb, ‘Mechanical comparison of 10 suture materials before and after in vivo incubation’, JSurg Res, 1994 56(4) 372-377.
3 C Chu, J A von Fraunhofer, H P Greisler, Wound Closure Biomaterials and Devices, New York, CRC Press, 1997. 4 J W S Hearle, B Lomas, W D Cook, I J Duerdon, Fibre Failure and Wear of Muterids, Ellis Horwood, Chichester, 1989. 5 G H Altman, F Dim, C Jakuba, T Calabro, R L Horan, J Chen, H Lu, J Richmond, D L Kaplan, ‘Silk-based biomaterials’, Biomatm‘ds,2003 243) 401416.
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WEARABLE MICROWAVE RADIOMETRYDEVICE FOR EARLY DETECTION OF SUB-TISSUE ONCOLOGICAL IMPERFECTIONS T Shah and E Siores Institute for Materials Research and Innovation, University of Bolton, Bolton, BL3 5AB ABSTRACT Breast cancer is the most common cancer among women, other than skin cancer, and is the leading cause of cancer-related deaths in women. Screening and early diagnosis are currently the most effective ways to reduce mortality. Scientific evidence shows that thousands of lives could be saved each year with treatment, if early symptoms of breast cancer are detected. Currently, a number of strategies and methods are adopted to facilitate detection, however, diagnosis is mainly focussed on the analysis of the existing condition and is very cost- prohibitive, time-consuming and requires trained personnel to use the detection equipment. The incidence of the earliest form of breast cancer, ductal carcinoma in situ (DCIS), has increased very significantly over the last few years worldwide and this seems to be directly related to successful medically assisted screening programmes. However, at present, there are no effective selfindicating early warning systems (SEWS) available that could be used without the assistance of qualified personnel for most cancers, including breast cancer. A potential non-invasivetechnique that can be developed as SEWS, is discussed in this paper where the passive electromagnetic thermal radiation emitted fiom human body can be monitored using suitable microwave antennae arranged in an appropriate configuration to cover the concerned breast area. Microwave radiometry principles can be employed to deconvolute sensor informaiion fiom subcutaneoustissues up to a few centimeters in depth. The device can be incorporated into a bra structure and provide an early breast cancer detectiodidication technique that is simple, quick and can be used by women without causing any hindrance to their daily activities. Furthermore, it can also be incorporated into a brief for the early diagnosis of prostate cancer in men.
INTRODUCTION Breast cancer is the leading cause of cancer-related deaths in women ages 40-55. Each year in the US., over 180,000 women are diagnosed with breast cancer and 46,000 women die of this disease. In all, 10%-1 1% of all women can expect to be affected by breast cancer at some time during their lives. The causes of most breast cancers are not yet understood. Screening and early diagnosis are currently the most effective ways to reduce mortality h m this disease. According to the American Cancer Society there were an estimated 211,240 new cases of breast cancer in 2005 and more than 40,000 deaths h m the disease in the USA. One in twelve women in the United Kingdom develops breast cancer and the annual death toll stands at 14,000. Over 33,000 new cases are being monitored year on year in the UK. According to the breast cancer advocacy group, less than one-third of American women follow doctors’ guidelines for having a mammogram. Early diagnosis and treatment are the keys to surviving breast cancer. Studies h m the American National Cancer Institute show that 96 percent of women whose breast cancer is detected early live five or more years after treatment. Thousands of lives could be saved each year with treatment if early symptoms of breast 0 Woodhead Publishing Limited, 201 0 437
cancer are detected. Taking full advantage of early diagnosis and treatment means that screening technology should obey the following features: High detection success rate, speed of procedure, comfort to the subject and very low health risk. In addition, it has to be taken into account that breasts of young women are denser as compared to postmenopausal women. Therefore, certain techniques are more difficult to use in this case for screening purposes. In this paper we discuss the development of a wearable early warning system for breast cancer, based on microwave radiometry.
MAIN TYPES OF BREAST CANCER The most common types of breast cancer are:
Carcinoma in sifp: This term is used for early stage cancer, when it is confined to the place where it started. With reference to breast cancer, the cancer is confined to the ducts or the lobules, depending on where it started. It has not gone into the fatty tissues in the breast nor spread to other organs in the body.
Ductal carcinoma in sitn @CIS): This is the most common type of non-invasive breast cancer. The cancer is confined to the ducts and has not spread through the walls of the ducts into the fatty tissue of the breast. Nearly all women with cancer at this stage can be cured. The best way to detect DCIS early is with a mammogram. Lobular carcinoma in situ (LCIS): This condition begins in the milk-making glands but does not spread through the wall of the lobules. Although not a true cancer, LCIS increases a woman's risk of getting a more malignant cancer at a later stage. For this reason, it's important that women with LCIS follow the screening guidelines for breast CanceT. In6ltrating (invasive) ductal carcinoma (IDC): This type of cancer starts in a milk passage or duct, breaks through the wall of the duct, and invades the fatty tissue of the breast. From there it can spread to other parts of the body. IDC is the most common type of breast cancer. It accounts for about 80% of invasive breast cancers.
Infiltrating (iivasive) lobular carcinoma (LLC): This type of cancer starts in the milk glands or lobules. It can spread to other parts of the body. About 10% of invasive breast cancers are of this type. DETECTION OF BREAST CANCER
Currently breast cancer detection is a three part procedure. The first part is identification of the abnormality in the breast tissue either by physical examination or by an imaging technique. Secondly the abnormality is diagnosed as a benign or malignant condition by using additional diagnostic methods or by biopsy and microscopic examination of the tissue morphology. The third part is concerned with biochemical characterisationof the malignant tissue in order to stage the cancer according to the size of the tumour and extent of invasion and metastasis. This then determines the prognosis and appropriate course of treatment. The National Cancer Institute (NCI) is funding numerous research projects to improve conventional and develop other new technologies to detect, diagnose, and characterise breast cancer. According to the U.S. Institute of Medicine, an ideal breast 438 0 Woodhead Publishing Limited, 201 0
screening tool is a low risk device that is sensitive to tumours, detects breast cancer at an early stage, non-invasive, simple to use, cost effective and widely available. The device should also involve minimal discomfort to the user and provides easy to interpret, objective and consistent results. Of particdar importance is the ability to clearly distinguish between malignant and benign tumours and early detection. A brief review of the published literature shows that all techniques have limited capability in these respects and surgery is required to establish the nature of the tumour. This characteristic also shows why research in this area is time consuming: the ultimate test of a technique beyond the proof of concept stage must be clinical trials. Potentially, microwave techniques have many of the above-mentioned features. Microwave systems in use or under development may be classified as passive, active or hybrid. The Passive technique has been investigated for many years, with clinical trials undertaken and commercial units available. It is used in conjunction with mammography. There is indication that it can pick up malignant tissue at an early stage, but as yet this cannot be taken as an established fact. Passive methods detect regions of increased temperature (due to the tumour) fiom the very small "natural" microwave signal from the breast (black body radiation as given by Planck's law). The signals detected are very low and require sensitive electronic systems. Temperature differentials between adjacent areas on the breast are taken as an indication of an abnormality, using a similar area on the other breast as a reference - the approach is somewhat empirical. The increased tumour temperature is thought to arise h m "vascularisation" (growth of blood vessels into a tissue). Current research involves developing thermal models of the breast to relate the measured temperature differentials with temperature rises located in the tissue. Work in the last few years carried out in the USA is related to the development of detecting antennas. Current understandings of the underlying pathological mechanisms for increased temperature in breast cancer are that breast cancer cells produce nitric oxide, which interferes with the normal neuronal (nervous system) control of breast tissue blood vessel flow, by causing regional vasodilation in the early stages of cancerous cell growth, and enhancing angiogenesis (new blood vessel formation) in later stages. The subsequent increased blood flow in the area causes a temperature increase relative to the normal breast temperature. Deep breast lesion processes may also contribute to the detectable increase in heat. These changes relate to physiological breast processes. It is believed that in healthy individuals, temperature is generally symmetrical across the midline of the body. Subjective interpretation of many diagnostic imaging modalities, including microwave thermometry and infi-ared thermography, relies on the underlying philosophy that normal contralateral images are relatively symmetrical, and that small asymmetries may indicate a suspicious lesion. Therefore, in breast cancer, thermographyfthermometry detects disease by identifying areas of asymmetric temperature distribution on the breast surface. Recent work has shown that there is a difference in electrical properties between healthy and malignant breast tissues, this is utilised by the active and hybrid systems and also lower fiequency electrical impedance tomography. The current strategies and methods adopted to facilitate detection and diagnosis of breast cancer include: Breast awareness and breast self-exam (BSE), Mammography, Magnetic Resonance Imaging (MRI) and tumour markers. Tumour markers are substances produced by cancer cells 0 Woodhead Publishing Limited, 201 0 439
and sometimes normal cells. At the present, there are no tumour markers that are useful for diagnosis of early stage breast cancer. Currently, the frontline strategies for breast cancer detection still depend essentially on clinical and self-examination and mammograms. The limitations of mammography, with its reported sensitivity rate often below 70??are recognized and the proposed value of self-breast examination is being queried *. Mammography is accepted as the most reliable and costeffective imaging technique, however, its contribution continues to be challenged with persistent false-negative results - ranging up to 30% 3, Most of the research and development activity related to cancer detection and diagnosis is focussed on the analysis of the existing condition and is costly, timeconsuming and requires trained personnel to use the equipment. However, the incidence of the earliest onset form of breast cancer @CIS) has increased very significantly over the last few years in the United States and this seems to be directly related to successful screening programs. This clearly shows that there is a need and scope for developing early breast cancer detection techniques that are simple, quick and can be used by women by themselves. The Institute for Materials Research and Innovation at University of Bolton is working on a research and development programme, which addresses these issues. The detection system, based on the use of microwave radiometry, will warn the user if there is any abnormal cell activity taking place within the body area covered by the device, such as the breast. Currently OUT focus is principally on the development of early warning systems (EWS) for breast cancer, however, once the generic detection technologies have been developed and established, preliminary work for the development of EWSs for other sub-tissue abnormalities such as prostate cancer will also be undertaken.
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MICROWAVE RADIOMETRY Microwave radiometry is a technique used in the field of diagnosis of diseases by measuring small changes of internal tissue temperature. The detection and diagnosis is conducted by measuring the intensity of natural electromagnetic radiation of patients' internal tissues at microwave frequencies. The intensity of radiation is proportional to the temperature of the tissues. Cancerous tumours have a significantly Merent index of refraction and the internal tissue temperature often changes due to inflammation, changes in the blood supply or increased metabolism of cells during oncological transformation of tissues. Microwave radiometry measures the emission of natural radiation ftom the body in the microwave or centrimetric region of the electromagnetic spectrum. All materials above absolute zero emit natural, thermally generated electroma$getic radiation. At body temperature of 37°C the maximum intensity of radiation occurs in the infia-red part of the spectrum at wavelengths close to 10 micrometers '. Microwave thermometry is the detection of microwave radiation from the human body and may be envisioned better as the microwave analog of infrared thermography Whereas inikared thermography uses wavelengths of 10 mm (typical), microwave thermometry makes use of much longer wavelengths, typically 1 -20 cm. This leads to important and fundamental differences between the two techniques as described in a number of publications '-lo. Microwave radiation is capable of penetrating human tissue and therefore the emission provides information related to subcutaneous conditions within the body. The intensity of microwave emission is linearly proportional to the temperature emission ftom the body. This means that microwave thermometry provides
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information on internal body temperatures. The depth of penetration, and hence the depth fiom which microwave radiation may escape from the body, depends on the wavelength, the dielectric properties of the tissue, and, most importantly, on the water content of the tissue. The distinctive feature of Microwave Radiometry is an extremely low signal strength entering input of the antenna from the biological tissues. This signal strength is approximately lOI3 Watt. While conducting the measurement it is necessary to distinguish temperatures differing on a tenth part of degree, which corresponds to a Watt. Therefore the special circuits are applied for receipt, signal strength of amplification and treatment of signals. Microwave Radiometry provides a measuring intensity of natural electromagnetic radiation of patients’ internal tissues, accuracy of 0.06 %. The application of Microwave Radiometry has, for the most part, been directed at the early detection and diagnosis of breast cancer. Present detection techniques other than radiometry require that the tumour have mass and contrast with respect to the surrounding tissue (i.e., palpation physical examination, mammography, ultrasonography and diaphonography). Results in approximately 85 percent of all determinations of breast disease result in extensive surgical procedures. Early detection could lead to a more conservative treatment and a better prognosis. The diagnosis of breast cancer at a smaller size or earlier stage will allow a woman more choice in selecting among various treatment options. Radiometric techniques represent a passive, non-invasive, non-ionizing procedure determining thermal activity rather than mass, that when used in conjunction with one or of the other methods, could provide early detection. The determination of thermal activity is a measurement of tumour activity, or growth rate, providing data beyond the physical parameters (i.e., size and depth determined by mammography). Suspicious results found by screening using microwave radiometry could then be referred for further investigation by mammography and other appropriatetechniques. Medical microwave radiometry has a number of positive characteristicsas follows:
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Early diagnosis of diseases; Possibility of non-invasive detection of disease in internal organs before the appearance of structural changes that can be detected by X rays or ultrasonography; Harmless for patients of all ages and with any underlying diseases. Also harmless for the medical staffconducting the procedurc. Possibility to conduct the investigationrepeatedly (control of treatment): Depth of anomaly detection is from 3 to 10 cm; Accuracy of measuring the internal averaged temperature f 0.2 C Simplicity of the device handing, the procedure may be conducted by the secondary medical M. Time measuring of one point: 5 - 15 sec.
MICROWAVE RADIOMETER DESIGNING AND TESTING Microwave radiometer is a device which measures the intensity of electromagnetic radiation fiom human body in microwave wavelength. The noise power at the input of the microwave receiver is proportional to the internal temperature of the human body. An array of receivers can resolve the local temperature inside the breast in 3-D and 0 Woodhead Publishing Limited, 2010 441
hence provide a signature of local temperature differenm inside the breast. The geometrical resolution is determined by the element number and the bandwidth and frequency of operation. Tumor detection relies on temperame difference resolution, which is a function of the noise figure of the receiver, its stability and the bandwidth, as well as the test integration time ‘ I . Aspects of application of electrodynamics and microwave in medicine have been studied. Traditional microwave radiometers for breast cancer detection known from literature and available on the market are rather large and heavy in weight. Today, only one relatively compact model of microwave radiometer @‘I’M-01-RES) is available on the market. The radiometer receives energy-emissions from the human body using an infrared sensor and a microwave sensor. The weight of the internal temperature sensor is rather high and consequently it is not possible to incorporate such a device in a selfpowered wearable system. It is therefore necessary to design a miniatm balance zero Microwave Radiometer and Microwave Multi-Channel Electron Switch (MMCES). Miniaturization is essential for both technical reasons; achieving direct coupling to antenna and good stability, as well as for integration into textiles for maximum comfort. In traditional microwave systems antennae are fabricated on rigid substrates, as wires or as hollow structures. Antennae on textiles have been demonstrated earlier ‘*-I8, but only with limited design variations, mainly as microstrip patch or slot antennae. There is a need to explore m e r e n t structures especially in view of multi-fkquency or wideband operation. The relevant accuracy of measuring the noise power at the input of the receiver is 10”. The dielectric constant of each person may change dramatically from 5.5 for breast fat tissue to 50 for muscle. So the reflection coefficient between antenna and human body tissue may change significantly. About 10% of energy may be reflected from the antenna. However, the accuracy of noise power measurement should remain unchanged. To solve this problem it is necessary to use zero balance radiometer with compensation of reflections between antenna and human body tissue. This principle is realized in most modern microwave radiometers 19-21. An overview of microwave radiometry is given in a recent publication ’O. The balance multi-fiequency microwave radiometer has also been described 19. These researchers used 5 frequencies in calculating the temperature profile in the brain. It is very important to use multifrequency radiometer in order to visualize the temperature inside body. But the increase in the number of frequencies increases the size and the weight of the radiometer and decreases the noise immunity of the device. The radiation from the human body is very small. So the noise immunity is one of the critical parameters of the microwave radiometer. It is evident that multi frequency radiometer will have better accuracy for breast cancer detection in comparison with single channel radiometer. But it is not evident that the sensitivity will increase greatly. Thousands of measurements during 10 years with the RTM-01-RESradiometer show 22 that there are about 10 percent of breast cancer patients who have no skin temperature increase and brightness temperature increase. So the probability that these patients will have a temperature increase at another frequency is not very high. Due to the weight and size limitations for a wearable system, there is no reason to use more then two fiequencies. Furthermore, skin temperature information is very important for breast cancer detection. The fluctuation error of the radiometer is dependent on time of integration, the bandwidth and losses of the microwave part of the receiver. Usually for the receiver’s bandwidth 500-600 MHz the measurement time is 5 seconds and fluctuation error is 0.1
-
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C. The increase of bandwidth may decrease the fluctuation error. Another possibility to decrease the fluctuation error is to increase the integration time. MMIC provides the opportunity to increase the bandwidth of the microwave device greatly. However circulators are very limited in this parameter. For wearable, selfexamination devices the time of measurement is not a very important factor, h a f o r e , the fluctuation error may be minimized by choosing the proper value of integration time. It may be possible to combine a single channel microwave radiometer and a MMCES. In this case, the results of brightness temperature measurement will highly depend on the environment temperature, due to the losses in the MMCES. To overcome this problem, it is necessary to use balance zero radiometer and balance the losses of MMCES and losses of reference noise source. In this situation the losses of MMCES do not decrease the performance of the radiometer. One possibility for minimizing the losses in MMCES is the utilization of integrated radiometer front-ends. The integration requires the design and fabrication of microwave monolithic integrated circuits with ultra low-noise performance. This can be achieved using state-of-the-art MMIC fabrication processes. Such components are very compact (few square millimeters) and therefore minimize losses and temperature variations. The employed fabrication processes can achieve amplifiers with noise fi below NF<0.5 with high gain resulting in excellent radiometer performance YHowever, these devices are either large and operate at cryogenic temperatures or are relatively narrowband. There is a need to especially focus on wideband for multi-fnquency receiver realizations in order to improve the overall system performance. Another possibility is the introduction of multi-receiver system alleviating the need for an MMCES. This however requires identical channel operation, which can only be assured using identical components. In case of MMIC realization of the radiometer front-end, such a technique becomes feasible. Introduction of microelectronic microwave components close to the antenna demands for appropriate interconnect technologies on textiles. This aspect has been dealt with in various publications, both with woven and non-woven materials 24-30. However, only little data is available on the microwave properties of different woven and non-woven materials 13. This deficiency must be overcome. Interconnection to the microwave monolithic integrated circuit is an important area of research and development. One possible approach is the implementation of ribbon type interconnects, which can efficiently be used for power supply and low frequency output signals. The active components need to be developed with MMIC operating over a wide range. Low-noise amplifiers determine the overall noise performance of the receivers. Very wideband erformance has been demonstrated in GaAs and CMOS technologies, respectively 31? However, in most cases a noise figure NP1.O dB over a fkequency range of DC - 10 GHz has been achieved. There is a need to design amplifiers complying with the frequency range of DC - 10 GHZ, but exhibiting a noise figure NF < 1.0 dJ3, with an associated gain of G > 30 dB. These parameters a~ well beyond the state-of-the-art today. The realized MMIC components will then be used for the assembly of the microwave radiometer system. Figure 1 shows the functional scheme of the Multi-channelMicrowave Radiometer.
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I
Figure 1. The functional scheme of Multi-channel Microwave Radiometer Multichannel Microwave Radiometer's developmentconsists of the following stages. Designing of a Multi-channel switch. 0 Designing of the Radiometer's microwave parts 0 Designing of the radiometer's digital part and analog low-fiquency part of the feedback circuit. 0 Software design for visualization of the measurements and for the Radiometer's microcontrollers. Development of a Multichannel switch is based on mathematical simulation of the microwave devices. The most important task for Multichannel switch to be wearable is to decrease its weight. Microwave radiometer consists of; an electronic switch, circulator, isolator, lownoise amplifier, filter, amplitude detector and miniature reference noise source with the temperature sensor. All foregoing components parts must be designed in miniature sizes using MMIC and plastic materials. There are two critical parameters which define the Radiometer's quality: 1. Brightness temperature error when the reflection's coefficient of the antenna changes. 2. Brightness temperature error when the environment's temperature changes. It is obvious that the human body's tissues have different permittivities so reflection coefficient of the antenna for some persons (or in some places of one person) can reach 10%. This fact can decrease noise power at the input on the radiometer. But brightness temperature cannot change in spite of the fact that the brightness temperature is proportional to noise power at the input on the radiometer. This problem can be overcome by balance zero radiometer with sliding scheme of the reflections compensation. Evidently the temperature of the microwave part of the radiometer may change greatly. This leads to noise power change at the radiometer input. If the bnt-end loss of the 444 0 Woodhead Publishing Limited, 2010
radiometer is about 1 dB, one degree change in the environmenttemperaturewill lead to a brightness temperature change of 0.4 degrees. This is why the radiometer input circuits temperature is usually stabilised. This is not feasible for the wearable selfpowered detection system because of power demand. For balanced radiometer it is possible to optimise input circuit parameters including Multi-channel Switch and Reference noise source circuit to minimise error due to environment temperature change. If losses of microwave part of radiometer do not change in time, the error due to environment temperature change can be compensated. For this purpose it is necessary to measure the hnt-end temperature. This principle was successfully used in industrial single-channel radiometer RTh4-01-RESand can be applied to the multi-channel radiometer. For this purposes this it is important to measure antenna array temperature and to transmit this information to the radiometer. Software is a need for visualization the results of measurement, database storage in the control centre. It is vital that radiometer should monitor the function of its various components appropriately, estimate the measurement error and transmit this information to the central database by wireless connection. This makes it possible to estimate the radiometer’s accuracy automatically. Fabrication of the breast cancer microwave screening system also requires the development of the hardware for the system.
DEVICE INTEGRATIONWITH FABRIC Development of a wearable, self-powered early warning system for breast cancer will require the production of textile structures that are flexible, comfortable, breathable, light, and suitable for integration with the materials developed tq perform various functions to operate the cancer detecting devices produced.
Figure 2. Temperature detection garments (left: female bra and right: male brief) show antenna discs distribution for cancer diagnosis Conducting fibres and filaments are needed to produce fabrics using a range of mechanical conversion methods, particularly knitting, crochet or braiding to produce the developmental materials. The structures then need to be characterised and optimised. Conducting fabrics can also be prepared using chemical methods, including coating, printing and lamination. Wet chemical methods and dry methods can be employed for this purpose. The integrated textile structures must be tested for their efficiency, durability, launderability, mechanical and comfort properties. Finally, the integrated textiles need to be converted into wearable structures to act as cancer detection devices.
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CONCLUSIONS Microwave Radiometry is non-hazardous both to the patients and to the personnel taking the thermograms, as during the examination the intensity of natural electromagnetic radiation from the patient’s tissue is measured. Temperature measurements are carried out non-invasively. Thermal changes precede to the anatomical changes that can be detected by traditional methods such as ultrasound, mammography and palpation. Thus microwave radiometry is a very promising method for the breast cancer detection at an earlier stage. The speciiic heat generation in the tumolu is proportional to the growth rate of the tumour. So fast growing tumors are “hotter”and they are more contrast in thermograms. Thus microwave radiometry is an unique method that allows early detection of all fast growing tumors. Using microwave radiometry in conjunction with other traditional methods allows to select patients with fast growing tumors. Studies show that breast thermometry has the ability to warn a woman that a cancer may be forming up to 10 years before any other test can detect it. The major gaps in knowledge can be addressed by more robust research on the technologically advanced microwave thermometry devices and large-scale, prospective randomised trials for population screening and diagnostic testing of breast cancer.
REFERENCES 1 E A Sickles, ‘Mammographicfeatures of early breast cancer’, Am J Roentgenol, 1984 143-461. 2 D B Thomas, et al, ‘Randomized trial of breast self-examination in Shanghai’, Methodology and Preliminary Results, J Narl Cancer I s t , 1997 5 355-65. 3 M Moskowitz, ‘Screening for breast cancer. How effective are our tests?’ CA Cancer JClin, 1983 33 26. 4 J G Elmore, C F Wells, M P H Carol, ‘Variability in radiologists interpretation of mammograms’, N U M , 1994 331(22), 1493.
5 S Fraseri, et al, ‘Microwave Thermography - an index of inflammatory joint disease’, British Journal OfRheumatOlogy, 1987 261 37-39. 6 A H Barrett,et al, ‘Microwave thermography in the detection of breast cancer’, AJR, 1980 134 365-368. 7 A H Barrett, P C Myers, ‘Microwavethermography’, BibIRadiol, 1975 7 45-56. 8 A H Barrett, P C Myers, ‘Subcutaneous temperatures: a method of noninvasive sensing’, Science, 1975 90 669-671. 9 A H Barrett, P C Myers, N L Sadowsky, ‘Detection of breast cancer by microwave radiometry’, Radio Science, 1977;l 2 [suppl]: 167-171.
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10 A H Barrett, P C Myers, N L Sadowsky, ‘Microwave thennography of normal and cancerous breast tissue’, Conference on thermal characteristics of tumors: applications in detection and treatment, New York, March, 979. Ann W A c a d Sci, 1980.
1 1 N Skoy ‘Microwave Radiometer Systems, Design and Analysis’, Artech House, 2006. 12 M Klemm, et al, ‘Novel small-size directional antenna for UWB wBAN/WPAN applications’,IEEE Trans. on Antennas and Propagation, 2005 53( 12) 3884-3896. 13 Locher, ‘Technologies for System-on-Textile Integration’, PhD Thesis, ETH ZUrich, Ziirich, Switzerland, 2006.
14 M Klemm and G Troester, ‘Em energy absorption in the human body tissues due to UWB antennas’, Progress In Electromagnetics Research, 2006 62 261-280. 15 N Behdad, ‘A wideband mulhsonant single-element slot antenna’, Antennas and Wireless Propagation Letters, 2004 3 5-8.
16 M Klemm, I Locher, and G Troster, ‘A novel circularly polarized textile antenna for wearable applications’, 3 4 European ~ Microwave Contrence (EuMC), 11-14,2004.
17 A Alomainy, Y Hao, C G Parini and P S Hall, ‘Comparison between two different antennas for UWB onbody propagation measurements’, IEEE Antennas and Wireless Propagation Letters, 2005 4 3 1-34. 18 M Klemm, G. Troster, ‘Integration of electrically small UWB antennas for bodyworn sensor applications’, IEE Wideband and Multi-band Antennas and Arrays, 2005 141 -1 46. 19 Y Leroy, et al, “on-invasive microwave radiometry thermometry’, Physiol. Means, 1998 19 127-148. 20 J W Hand, et al, ‘Monitoring of deep brain temperature in infants using multifrequency microwave radiometry and thermal modelling’, Phys Med. Biol, 2001 18851900. 21 J W Lee, et al, ‘A novel design of thermal anomaly for mammary gland tumor phantom for microwave radiometer’, IEEE Trans. Biomed. Engineering, 2002 49 694699. 22 L M Burdina et al, ‘Tikhomirova ((microwave radiometry in algorithm complex diagnosis of breast diseases’, Modern Oncology, 2005 6(1) 8-9 (in Russian). 23 J Dabrowski, et al, ‘Design and performance of low noise cascode IC for wireless applications’, 15&ini conf Microwaves, Radar and Wireless Communications, 3 882885 May 2004. 24 M Catrysse, et al, ‘Towardsthe integration of textile sensors in a wireless monitoring suit’, Sensors and Actuators, 2004 A114 302-31 1. 0 Woodhead Publishing Limited, 201 0 447
25 J Coosemans, B Hermans, R Puers, ‘Integrating wireless ECG monitoring in textiles’, int conf Solid-state Sensors and Acmtors, Transducers 05, 228-232, June 59,2005. 26 B Hermans, J Coosemans, R Puers, ‘Integrationof sensors and electronics in textile for use in infant medicine’, int c o d European Microlectronics and Packaging Conference andExhibition, 588-592, June 12-15,2005, 27 L Van Langenhove, et al, ‘Textile electrodes for monitoring cardio-respiratory signals’, int c o d Protective Clothing, Montreux, Switzerland, CDROM poster no. 27, May 2 1-24,2003. 28 L Van Lmgenhove, et al, ‘The use of textile electrodes in a hospital environment’, int conf AVTEX - World Textile Conference, Gdansk, Poland, 286-290, June 25-27, 2003. 29 E P Scilingo, et al, ‘Performance evaluation of sensing fabrics for monitoring physiological and biomechanical variables’, IEEE Tran Information Technology in Biomedicine, 2005 9(3) 345-352. 30 R Paradiso, G b r i g 4 and N Taccini, ‘A wearable health care system based on knitted integrated sensors’, IEEE Tran Information Technology in Biomedicine, 2005 9(3) 337-344. 31 2 M. Nosal, ‘Simple model for dynamic range estimate of GaAs amplifiers’, IEEE-
M7“S,Proc. Intern. Microwave Symp. 2001. 32 J Jung, et al, ‘Ultra-wideband low noise amplifier using a cascode feedback topology’, IEEE Silicon Monolithic Integrated Circuits in RF Systems, 2006 Digest of Papers. 2006 Topical, 202-205. 33 J Xu, et al, ‘GaAs 0.5 dB NF dual-loop negative-feedback broadband low-noise amplifier IC’, IEE Electronics Letters, 2005 780-782. 34 Y Wang, J S Duster and K T Komegay, ‘Design of an ultra-wideband low noise amplifier in 0.13111 CMOS’ IEEE International Symposium on Circuits and Systems, May 2005.
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INVESTIGATION OF DIFFERENCES IN CAPROSYN,BIOSYN, POLYSORB, NOVAFIL AND SURGIPRO SUTURES A D Erem', H H Erem' E Onder' 'Istanbul Technical University, Faculty of TextileTechnology and Design, Department of Textile Engineering, Istanbul, TURKEY 2GATA Haydarpasa Training Hospital, Department ofl Surgery Uskudar, Istanbul, TURKEY
ABSTRACT In this study, different properties of different types of absorable and nonabsorable sutures are investigated. For this purpose, two numbers of four different suhues and three sutures with two different counts were tested. These sutures are Biosyn, Caprosyn, Polysorb, Novafil and Surgipro. The number of the sutures are USP 0 and USP1. The strength of these yarns was tested ia the Instron 4301 model strength tester device according to ASTM D3822-01 and ASTM D3217. The needle attachment forces of them are tested too. Test results were evaluated statistically. At the end of the study, it was shown that the material structure, yarn count, have a significant effects on the suture strength, elongation.
INTRODUCTION A suture is a strand of material that is used to approximatetissue or to ligate blood vessels during the wound-healingperiod [I]. A variety of materials have been used with catgut and silk being the most prevalent until the development of synthetic fibers during the 1950s [2]. As shown in Table 1, sutures can be classified according to three characteristics origin, absorption characteristics and fiber construction. Table 1. Classification of Sutures [3] Characteristic Categories origin Natural Synthetic Absorption Absorbable Non-absorbable Fiber construction Multifilament Braid Monofilament An absorbable suture was one that lost a significant portion of its mechanical strength over a period of 2 months while a non-absorbable suture was one that maintained a significant portion of its strength longer than 2 months [4]. A suture may lose its tensile strength over a relatively short period of time, but require months or even years to absorb completely and be eliminated fkom the body. The primary mode of degradation for natural materials is enzymolysis, whereas for synthetic absorbable materials it is hydrolysis [3]. The suture is woven into fibers in order to maximize the resulting strength. For materials that possess a high tensile modulus, yams composed of low-denier filaments are fabricated into a multifilament braid in order to achieve adequate suppleness. Materials that a tensile modulus of about 500 kpsi or less can be fabricated into 0 Woodhead Publishing Limited, 2010 449
monofilaments with acceptable handling characteristics although the optimum range is about 350 kpsi or less [3]. Polyester based sutures include those based on poly(ethy1ene terephthalate) (PET), poly(buty1ene terephthalate) (PBT), and polybutester, which is polyether-ester derived from poly(tetramethy1ene glycol), lY4-butanediol,and dimethyl terephthalate. All are produced by condensation of corresponding diol or glycol with terephthalic acid or an ester of terephthalic acid. PET is a hard, bri!Ae material, while the longer segment in PBT renders it somewhat less brittle. The longer soft segment with ether linkage in the polybutester reduces the tensile modulus enough that it can be fabricated as a monofilament. With minimal tensile strength loss, the polyester offers excellent longterm support [3]. Polypropylene sutures are based on isotactic polypropylene, polymerized fiom propylene using a Ziegler-Natta catalyst. Polypropylene causes one of the lowest tissue reactions and does not lose strength after it is implanted. Because of its smooth d a c e , carell knot tying is required in order to secure knots [ 31. Differences in processing of polypropylene can lead to differences in suture toughness, surface smoothness and surface hardness, characteristicsthat can contributeto the relative level of rupturing and breaking when tying knots 161. Biosyn sutures are synthetic absorbable monofilaments. Biosyn has a strength-loss profile that is shorter or longer than absorbable braids. Biosyn copolymer is based on a two-step process. The first block is a random PTMCPDO copolymer while the end blocks are random PGAPDO copolymers [7]. The newest synthetic absorbable monofilament suture is Caprosyn. This product was designed to meet the surgeon’s need for a supple, fast absorbing monofilament for use in plastic surgery and to replace catgut. This material is a tetrapolymer, made by copolymexizing glycolide, &-caprolactone,L-lactide, and TMC in 68/17/7/7 weight ratio [8]. Too much poly-caprolactone (PCL) in the final polymer and it will be very supple but weak; too little and it will be strong but stiff. Caprosyn loses all strength by 3 weeks and is absorbed by the body in 56 days, making it the fastest absorbing synthetic monofilament [3]. A needle enables the suture strand to be passed through the tissues that are to be approximated. The most important characteristics of a needle include sharpness, strength, profile, corrosion resistance, and durability. Additional characteristics such as length, curvature, and wire diameter are considered by the surgeon during product selection [3]. Table 2. Surgical needle type [3]
Taper-cutting
Description A circular cross section smoothly increasing - in diameter h m tip to body A triangle cross section smoothly increasing in diameter from tip to body A taper-point needle with small facets ground at the tip to provide some cutting effect
Spatula or diamond
A sharp, flat tip tapering back to triangular body Ophthalmic
Type
Taper point Cutting
uses
Cardiovascular and general surgery Plastic surgery Cardiovascular and general surgery
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All needles start with high quality stainless steel wire. The first step is to drill a hole in the wire that will accommodate the suture to be attached to the needle. The holes are commonly drilled mechanically or with a laser [3].
MATERIAL Biosyn sutures are monofilament Glycomer TM 613 synthetic absorable sutures. Biosyn sutures are prepared fiom synthetic polyester, composed of glycolide (%60), dioxannone (0/014), and trimethylene carbonate (%26). Biosyn sutures are suitable for use in general soft tissues. But they are not suitable for use in cardiovascular and neurological surgery. Loss of tensile strength and absorption of Biosyn suture occurs with the hydrolysis of suture. During the hydrolysis. Absorption of biosyn sutures are completed between 90 and 110 days [9]. Caprosyn sutures are monofilament synthetic absorbable sutures, which are prepared fiom Polyglytone TM 6211. Polyglytone 6211 is composed of glycolide, caprolactone, trimethylene carbonate and lactide. Caprosyn sutures are suitable for use in general soft tissue but it is not suitable for use in cardiovascular or neurological surgery, microsurgery and ophthalmic surgery. Loss of tensile strength and absorption of Caprosyn sutures occurs by hidrolysis. Caprosyn has a rapid absorption characteristic. Absorption of Caprosyn is completed by 56 days. Caprosyn has high knot strength, pliability and handling [9]. Novafil, nonabsorbable monofilament surgical sutures are composed of polybutester, a copolymer of butylene terephthalate and polytetramethylene ether glycol. The unique properties of Novafil monofilament suture are attributed to the composition and structure of the polybutester fiber which give the suture: Suppleness and easy handling, unique elasticity and flexibility, high knot security, less tissue drag and smooth knot rundown, flay resistance, unique resistance to creep and structural fatigue This suture, being absorbable, should not be used where extended approximation of tissue is required. Novafil monofilament sutures elicit a minimal, transient acute inflammatory reaction in tissues, which is followed by gradual encapsulation of the suture by fibrous connective tissue. Novafil monofilament sutures are stable against the action of tissue enzymes and do not degrade. Novaf3 monofilament sutures are nonabsorbable and no significant change in strength retention is known to occur in vivo.Gamma irradiation is the sterilisation method for this suture [9]. Surgipro sutures (clear or pigmented) are inert, nonabsorbable, sterile sutures composed of an isotactic, crystalline stereoisomer of polypropylene and contain polyethylene. The suture is pigmented blue to enhance visibility.The advanced extrusion process of the polypropylene molecule gives the suture: Uniform diameter, maximum flexibility of the strand, high security with snug and flattened knots, minimal memory and reduced “pig-tailing”, consistent knotting strength. polypropylene sutures are indicated for use in general soft tissue including use in cardiovascular, ophthalmic and neurological surgery. polypropylene sutures are nonabsorbable and no significant change in strength retention is known to occur in vivo Ethylene oxide is the sterilisation material[9].
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Table 3. Material properties
Representative Material Non-absorbable Polypropylene Non-absorbable Polybutester Absorbable Polyglytone 62 1 1 A b s o r b a bG1u comer 631 Suturetype
c
Monofilament Monofilament Monofilament Monofilament
Surgipro Novafil Caprosyn Biosyn
1 0, 1 0, 1 0,l
4 4,3.5 4,3.5 4,3.5
METHOD Sutures can be characterized by a number of different properties, all of which can be categorised into three groups; physical, handling and biological. Physical characteristics are dimensions, tensile strength, knot-pull strength, needle attachment force, knot security,coefficient of Ection, stifhess, memory, creep, swelling, capillarity. Handling characteristics are knot tie down, first throw hold, tissue drag, package memory, suppleness. Biological characteristics are tissue reaction, tensile strength loss, absorption, biocompatibility. In this study tensile strengtb, needle attachment force properties are investigated. Tensile strength is the maximum tensile stress that can be applied to the strand. The tensile strength of these yarns was tested in the Instron 4301 model strength tester device according to ASTM D3822-01 and ASTM D3217. Needle attachment force is the force required to separate the needle and strand. This test takes place on the Instron 4301 too.
RESULTS The tensile strength, tensile elongationand needle attachment force have been measured and average results are given in Table 4. Table 4. Tensile strength properties of samples SutureType Count (USP)
CapmSYn Biosyn Surgipro
0 1 0 1 0 1
Novafil
1
Mean Tenacity (Kgf) 9,5&t0,38 12,455 0,27 13,77+ 0,69 1 6 ; l e 0,07 5,342 0,02 7,64 20,04 9,52+0,07
Strain(%) 52,29+ 3,06 41,652 1,011 41,212 1,18 27,78+1,I4 46,02+1,08 43,015 0,53 46,17+0,20
Suture strength is related with crystalline and amorphous regions in its structure. The reduction in amorphous regions causes the reduction in elongation. As the elongation of the suture decreases, the tensile strength decreases, because of the reduction in the mobility of molecules. The tensile strength and tensile elongation of four different sutures are expressed graphicallyin Figure 1 and Figure 2.
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0
S 01 Sl
5
sz
5
02
m
OE
SE OP
SP 0s
.......
C’apnisyn
Riosyn
Surglpm
Suture Type
Figure 3. Comparison of tensile strength of two different counts of sutures
nI w
I
8 I Sl’l
Figure 4. Comparison of elongation of two different counts of suture
CONCLUSIONS Results show that there is a significant relation between suture tensile strength (elongation) and suture properties. When the crystallinity of the suture decreases, the tensile strength of it increases. Also the diamekr of the suture is important, when the diameter increases, the tensile strength increases and the elongation of it decreases. That is why, the material and count of sutures are important parameters. REFERENCES 1 C C Chu, ‘Recent advancements in suture fibers for wound closure’, ACS Symp Ser
High-Tech Fibrous, 167-211, 199 1.
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2 T H Barrows, ‘Degradable implant materials: a review of synthetic absorbable polymers and their applications’, Clin Muter, 1986 1 233-257. 3 M S Roby and J F Kennedy, Suture, Biomaterials Science, B D Ratner, A S HofEnan, F J Schoen, E L Lemons, eds. Elsevier Academic press, California USA, 2004. 4 N A Swanson and T A Tromovitch, ‘Suture materials, 1980s: properties, uses and abuses’, International Journal of Dermatology, 1982 21 373-378.
5 C C Chu, Chemical suture and manufacturing processes, Wound Closure Biomaterials and Devices, C.C.Chu, J. Von Fraunhofer and H.P. Greisler, eds. CRC Press, Boca Raton, FL, 65-106 1997.
7 M S Roby, S Bennett, M Kokish, and Y Jiang, Absorbable block copolymers and surgical articles fabricated therefrom. US Patent Office,Pat No 5 403 347,1995. 8 M S Roby, L Kokish, R Mehta, and J John, Absorbable polymers and surgical articles fabricated therefrom. US Patent Office, Pat No 6 235 869,2001.
9 Syneture Product Catalog (http://www.syneture.com/)
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PART VII
SMART MATERIALSAND TECHNOLOGIES
SMART MATERIALSAND TECHNOLOGIES: AN OVERMEW M. Miraftab Institute for Materials Research & Innovation, The University of Bolton, Bolton, UK
INTRODUCTION New technologies are constantly being developed to cater for increasingly sophisticated and demanding consumer society. This is particularly evident within the health sector where mobility, remote access and quick recovery are of prime concerns. The term "smart" has pushed the boundaries of traditional textile or fibrous-based materials over and beyond many engineering and science disciplines whilst engaging a wide range of professional researchers and technologists. Smart materials with predefined functionality and regulated responsiveness are now standard expectations of most materials used in this sector. The first steps towards smart behaviour started off with the advent of Chromic Materials") where textile fibres and fabrics were shown to display changes in colour when subjected to different stimuli i.e. light, heat, electricity, pressure and liquids. Given their rather narrow spectrum of functionality, they initially attracted the fashion, design and the sport industries. However, currently much research is in progress trying to develop them into precision indicators and reactive technical devices that could be utilised in a wide range of medical and technical applications'". Phase change materials (PCM) are relatively new and as implied they operate by way of generatinglabsorbing heat as they change from liquid to solid phase or vice versa. Once suitably encapsulated, PCMs can be included into foams or wated onto textile surfaces or even be embedded into extruded fibres"). Outlast@,one of the commercially available brand products uses encapsulated paraflin wax to capture the benefits of PCMS'~'. Excess heat from the body during normal activities or exercise are stored within PCMs and subsequently released when the body cools or is exposed to lower temperatures hence maintaining comfort to the wearer. Application of PCMs in hospital settings and medical textileddevices has been rather limited and there remains considerable need for optimisation and improvement in working efficiencies of such systems. Shape memory materials (SMM) much the same as chromic materials need an external stimuli to change their shapes(". The trigger causing the change in shape could be; heat, stress, magnetic or electric field, pH, UV light or even water. Most available shape memory products have been based on metallic shape memo? alloys. However, shape memory polymers ( S M P ) and gels have now also appeared' ). Stimuli for such polymers are currently mainly heat but much research is in progress to identify other trigger mechanisms. The advantage of SMPs is their ability to be tailor-made with high shape recoverability, broad temperature range for shape recovery and there being biocompatible andor biodegradable. These highly desirable qualities make these materials attractive to a whole range of fibre or textile-based applications from decorative and design utilisation to technical and medical applications. Medical applications could include anything fiom laser stimulated S M P inserts in blood vessels where clots could be removed by twisted coil action of an otherwise straight iece of polymer thread(') to tightening and securing of a loosely sewn surgical operationp8). Electrically conductive polymers based on dispersion of conductive materials such as carbon into the dope solution and their subsequent extrusion has been around for a while. Although reasonably effective as conductive fibres, physical and mechanical 0 Woodhead Publishing Limited, 2010 459
properties of such fibres suffer as filler quantity is increased (i.e. 15-35% inclusion) to improve conductivity. By contrast however, only up to 2.5% filler content is required when more recently developed single walled carbon nano-tubes (CNT) are the mixing additive('). Given their highly desirable characteristics, much research is currently in progress to maximise overall strength and conductivity of these very interesting polymers. There currently exist a number of issues with nano-tubes including high costs and some degree of toxicity. Being phenomenally small, they could potentially cause damage by entering the respiratory system and other bodily functions. Further research on this aspects and large scale applicationsof nano-tubes are ongoing. Inherently conductive polymers are amongst the latest developments in conducting materials. The level of conductivityof these materials depends on molecular structure of the polymer backbone and the degree of doping. Their electrical conductivity can be engineered over a large range by controlling the degree of polymer doping. Polyaniline (PAN), Polypyrrole (PPy) and Polytiophene (PT) are some of the inherently conducting polymers that have achieved commercialisation following initial setbacks regarding processing difficulties in manufacture(''). They are increasingly used in the packaging industry where antistatic behaviour and electrical sensitivity are of concern. They can potentially be highly effective in suitably integrated formats within medical textiles and medical devices in particular. Nanofibres generated by application of electric charge into a visco-elastic liquid is increasingly attracting commercial realisations given the potential benefits of high surface area, better overall web strength and greater apparent ability to change properties i.e. by changing dope concentration, molecular wei f applied voltage, relative distance between delivery and pick up points and so on("" ). However, speed of production is still quite low for commercial production, although recently higher speeds of production with alternative extrusion and pick up geometries have been reported(13). Commercial production is still a way off but a lot of research and pilot production techniques are currently being tried around the world. The application potential of electrospun fibres are broad including anything from surface coating for solar absorption of heat and energy to antimicrobial and healing purposes. At nano-scale, they can be engineered to be made into structures with high efficiency and precisions as; filters, scaffolds, wound dressings, composites and so forth. Spider silk(14-15) is the strongest natural fibre pmduced by variety of spiders. Despite being made of proteins, the variation and complexity of the protein molecules are believed to be responsible for its ultra-strength. It is stronger than Kevlar and steel and yet it is extremely light and ductile allowing up to 140% extension. In recent past attempts have been made to artificially produce this fibre by breeding goats with spider genes. Nexia Biotechnologies the manufacturing company uses milk from such animals to produce the ultra strong and light weight fibres known as Biosteel. Once fully developed, the potential application of these fibres in medical healthcare, aviation and composite production will be overwhelming. Another development has been in the area of auxetic materials, these are natural or synthetic-basedmaterials that expand transversely when stretched along their They are said to have "negative" passion's ratio. Auxetic structures made from polymeric materials are claimed to have unique properties that could be highly beneficial in a number of engineering applications including; indentation resistance, enhanced shear resistance, ultrasonic sound and vibration damping and/or absorption. Their potential applications in medical field could include in prosthetic devices, implants, sutures, ligaments and even blood vessels. They can also be used in combination with piezoelectric sensors and actuators. Their inherent or imposed non-
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conventional behaviour upon application of stresses could be used to clean out filters or release drugs on demand and so on. Lately, synthetic auxetic fibres have been produced that could lead to a new generation of smart materials operating at micro-structural level(").
REVIEW OF PAPEW ON SMART MATERIALS As the ageing population reaches its peak, in most western countries, demand for hospitalisation and long term care continues to increase. This surge in demand triggers an exponential rise in the cost of treatment and aftercare which must be met by individuals, hospitals, healthcare centres and ultimately governments. Any technological progress that can help reduce costs and alleviate the burden would be well received. The first paper in this chapter tackles this very important issue by reporting on latest development in sensor technologies where optical sensors rather than electric sensors are implanted into wearable textiles to monitor respiratory movements, cardiac activities and other such like signals fiom the body. Another consequence of aged population is the lack of mobility which can lead to pressure sores and ulcers often caused by poor circulation of blood around the body. Specially designed mattresses and cushions with inbuilt pressure redistributions have been developed and widely used. The second paper presented in this chapter reports on new findings where acclaimed traditional pressure distributions in mattresses have been challenged. Effect of pressure relief on heel blood flow of healthy and diabetic s e e r s using four known alternating pressure air mattresses have been monitored in this work and the outcome suggests that low air cell pressures do not necessarily produce lower interface pressures which contradicts classical understandings. Type of clothing or uniform used in work wear could be potentially dangerous when used in heated environments or in vicinity of open flames. Inappropriate clothing can easily catch fire and cause horrific injuries to the wearer. The next paper in this series investigates the hazard potentials of different garments made fiom natural and synthetic fibres and introduces a new equipment that would measure pre-ignition and postignition heat fluxes released during buming at Werent angles. The paper concludes that post-ignition thermal properties play a major role in determining hazard potentials of textile garments. Pressure garments used in medical textiles are not necessarily designed for comfort. Their prime role is to perform a function and achieve desired results. However, as patient care and ethical issues relating to patient's rights and moral standings become increasingly important, objectivity in measuring mmfort becomes more relevant. The final paper in this chapter introduces a 3D form fit pattern developed fiom extended body measurements by analyzing variation in grid contours printed on a body suit. By understanding such complexities, the paper concludes that optimal garment pressure fit distribution for a given application could be predicted.
REFERENCES 1 T Komatsu, 'Chromic materials Part 1 - Liquid-crystalline behaviour and electrochromism in bis(octakis-n-alkylphthalocyaninato) lutetium(III) complexes', J Mat1 Chem,1994 4 533-536, DOI: 10.1039/JM9940400533 2 H Mattilla, Intelligent textiles and clothing, Woodhead Publishing, ISBN 1845690052,2006. 0 Woodhead Publishing Limited, 2010 461
3 S Raoux and M Wutting, Phase Change Materials: Science and Applications, Springer-VerlagNew York, LLC, ISBN-13:9780387848730,2008. 4 Outlast and Adaptive Comfort, http://www.outlast.com/index.php?id=95&L=O 5 Y Y Chu et al, Shape Memory Materials and their Applications, Materials Science Forum, Volumes 394 - 395,2002.
6 J Hu, Shape memory polymers and textiles, Woodhead Textiles Series No. 65,ISBN 1 84569 047 8,2007. 7 Removable embolus blood clot filter, US Patent Office, Pat No 5669933 - September 1997. 8 Smart suture is first application of http://web.mit.edu/newsoffic&OO2llanger-suture.html
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9 J F Colomer, ‘Synthesis of single-wall carbon nanotubes by catalytic decomposition of hydrocarbons’, Chem. Commun, 1999. 10 J Wang,‘Anion exchange nature of emeraldine base (EB) polyaniline (PAn) and a revisit of the EB formula’, Synthetic Metals, 2002 132 issue 1.
1 1 T H Grafe et al, ‘Nanofiberwebs from electrospinning,the nonwovens in filtration’ 5m int cod, Stuttgart, Germany, March 2003.
12 D Lukas et al, ‘Physical principles of electrospinning (Electrospinaing as a nanoscale technology of the twenty-first century)’, Textile Progress, June 2009, 41(2) 59140. 13 J Bowman, M Taylor, V Shama, A Lynch and S Chadha, Multispinneret Methodologies for High Throughput Electrospun Nanofiber, MRS 2003.
14 B. Handwerk, Artificial spider silk could be used for armor, More, National Geographical News, January 2005. 15 S Islam et al, Methods and apparatus for spinning spider silk protein, US Patent Ofice, Pat No 7057023,2006. 16 R H Baughman, Auxetic materials: Avoiding the shrink, Nature 425, 667 (16 October 2003) 1 doi:lO.l038/425667a
17 P Hook, AUXELM: LTD, Uses of Auxetic Fibres, US patent Office, Pat No US 2007210011 (Al), 2007.
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SMART TEXTILES EMBEDDED WITH OPTICAL FIBRE SENSORS FOR HEALTH MONITORING OF PATIENTS F.Pirotte' ,A. Depre2,RShishoo3,J. De Jonckheere4,A. Grillet' 'Centexbel, Avenue du Pam 38, Heme, Belgium 2Elasta, Textielstraat 15,8790 Waregem, Belgium 'Shishoo Consulting, Svartlavsv2igen 18, A s h , Sweden 41TM,EA1049, CHRU de Lille, Pavillon Vancostenoble, 59037 Line Cedex, France 'Multitel, Rue Pierre et Marie Curie 2,7000 Mom, Belgium
ABSTRACT Healthcare monitoring is a general concern in hospitals for patients requiring a continuous medical assistance. In order to increase the mobility of such patients, considerable efforts are underway worldwide with aim to develop wearable monitoring systems capable of measuring vital physiological parameters such as respiration movements, cardiac activity, pulse oxymetry and body temperature. Advances in sensor technologies is one of the key factors responsible for production of smart textiles for making wearable health monitoring products. This paper will describe the work being carried out in a European Union FF'6-IST Programme- supported project "OFSETHOptical Fibre Sensors Embedded into technical Textile for Healthcare". While most sensor development so far have been focussed on the use of electric sensors, the general objective of OFSETH is to take advantage of pure optical sensing technologies for extending the capabilities of medical textiles for wearable health monitoring. Keywords: health monitoring, MRI, smart medical textiles, fibre optic sensors
INTRODUCTION Smart textiles for health monitoring Healthcare monitoring is a general concern for patients requiring a continuous medical assistance and treatment. In order to increase mobility of such patients, a huge effort is pursued worldwide for the development of wearable monitoring systems able to measure vital physiological parameters such as respiration movements, cardiac activity, pulse oxymetry and temperature of the body. Smart textiles systems play an increasingly important role in these developments as they are well suited for wearability and can ensure comfort to the user. The truly wearable sensing interfaces must be easy to use and customised for patient requirements of age, body size and posture, state of mobility etc. The mechanical processing of integrating sensors must be done using industrially viable techniques which neither affects the durability nor the function of smart fabrics. Many sensors can be used to measure the strain and deformation in materials such as piezoelectric sensors, piezo-resitive sensors, and fibre optic sensors. During past few years a couple of EC financed projects have aimed at developing smart textiles and clothing for health monitoring of patients'. These projects are mainly based on a wearable interface implemented by integrating fabric sensors, advanced signal processing techniques and modern telecommunication systems, on a textile 0 Woodhead Publishing Limited, 2010 463
platform. Conductive materials in form of fiber and yarn are integrated in a garment and used as sensors, connectors and electrode elements. Breathing pattern, electrocardiogram, electromiogram, activity sensors, temperam, can be listed as physiological variables to be monitored through the proposed system. A miniaturized short-range wireless system is integrated in the sensitive garment and used to transfer the signals to PCs,PDA and mobile phones. One targeted application consists in the monitoring of patients suffering with heart diseases during and after their rehabilitation. Interesting results in this field are for instance the WEALTHY and MERMOTH' European projects, while in the US, the Lifeshirt@system developed by Vivometrics should also be mentioned3.
OFSETH RESEARcIf PROJECT Monitoring of anesthetized patients during Magnetic Resonance Imaging presents a lot of disagreements due to the presence of metallic and electronic components in the MRI field. Indeed, sensors including either metallic parts or electrical conductive wires can cause disturbance of the MRI result and burns on patient skin4. Alternatively, optical sensors offer the advantage of being free from metallic or electrical conductive wires, and in addition, can be remotely interrogated via an optical fibre cable so that the monitoringunit can be placed out of the MRI field. Therefore, the use of optical sensors instead of electrical sensors could reduce the electromagnetic disturbance and burning hazard for the patients. Optical sensors have already proved their capacity for physiological data acquisition especially in MRI environment, but, in most cases, they are not functional enough for a clinical use. Textile integration of such devices will increase their functionalityand then allow them to be used during medical procedures. On the other hand, induction of anesthesia usually takes place in a room adjacent to the MRI and the patient is then transferred into the MRI under general anesthesia. When MRI has been performed, the patient is transferred back - still anesthetized - to the MRI adjacent room. These transfers of anesthetized patients without any monitoring system are at risk of anesthetic complications. In that way, monitoring would best be continuous from induction to end of anesthesia, thus giving maximum security. However, many MRI compatible monitoring systems are not easily transportable. In many cases, the medical staff needs two or three different monitoring devices during the whole procedure: in the induction room, during transportation, and in MRI room.An easier and more efficient way would be to use a transportable - MRI compatible - monitoring device, that would be able to follow the patient h m "induction room" to "MRI room" without being removed. Moreover, given the variability in age, size and weight of the patients, the monitoring system has to be flexible and adaptable enough to be worn by a large number of patients. Therefore, a wearable, adaptable and easy to connect MRI compatible monitoring device would best meet these issues. Since March 2006, a new project supported by the EU under FP6 and called OFSETH (Optical Fibre Sensors Embedded into Technical Textiles for Healthcare)' was launched. The objective of OFSETH is the integrationof optical fibre based sensors into smart medical textiles for developing safer wearable solutions for patient monitoring more specifically during MRI magnetic Resonance Imaging) examinations. The required parameters to be monitored on sedated patients are: - ECG waveform and heart rate - Blood pressure - Plethysmograpbic waveform and oxygen saturation (Sp02) Respiratory rate
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Besides these functions, safety aspects are vital in developing these types of MRI compatible devices. One should avoid electric cables, metallic parts and prevention of bacteriologic and viral cross-patient contamination. One of the main advantages of optical fibre sensors is their immunity to electromagneticradiations.
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Figure 1. Schematic diagram of the OFSETH smart textile for the monitoring of anesthetisedpatients under MRI. The sensor part is in charge of acquiring the wavefonn, which is transmined to the optoelectronic module, where optical to electronic (0-E) conversion is performed. Finally, the signal is conditioned to be digitalized and transmitted to the monitor.
Regarding the identification and development of suitable optical fibre types, there lie many technological challenges ahead. These include: - Resistance to large mechanical forces and deformations in fabric production processes such as weaving and knitting - Sustainablelight propagation properties when integrated or embedded in the fabrics, - Preservation of sensing capabilities with regards to environmental fluctuations, - Compatibilitywith medical use and without negatively affecting patient’s comfort. OFSETH research focuses on how silica and polymer optical fibres can be used for sensing vital physiological parameters while being compatible with industrial fabric manufacturingprocesses. Specific developments of knitting and weaving techniques for embedding or integrating optical fibres as well as customized design of optical fibres are carried out in order to obtain suitable fabric making processes that neither causes mechanical damage to the optical sensors nor degrade their sensing properties. This development work takes also into consideration wear and care requirements of the monitoring textiles. Various protogyes of health monitoring wearable products will be developed and then used for clinical evaluation with patients and healthy volunteers.
Fibre optic sensors Investigation of the capabilities of optical fibre sensors for healthcare monitoring in MIU environment has been largely reported in the past, due to the well-known immunity of fibre optics against electromagnetic radiations. Especially, monitoring of respiratory motions andfor detection of heart beats were demonstratedusing pure optical methods, in particular the bending loss technique using either a coil or a loop shape, the 0 Woodhead Publishing Limited, 2010 465
interferometry technique, and the grating technique using fibre Bragg gratings (FBG‘). In OFSETH, three sensing techniques have been proposed for the monitoring of respiration using fibre sensors embedded into textiles, which can be manufactured using a simple machine process. The main issue for all sensors is how to transmit the elongation of the wearable smart fabric to the optical fibre: - the bending loss sensor (Intensiw sensor): the elongation due to movements modifies the waveguide properties of the optical fibre that looses light in case of angles => the intensity varies at the detector location - the OTDR sensor (Distributed reflectometry sensor): the stress applied to the fibre locally modifies the amount of reflected or backscattered light the FBG sensor (Spectrulsensor): the elongation of the optical fibre results in a change of the coloudwavelengthof the reflected light
Integrationof optical fibres in smart textiles Due to their fibrous nature,optical fibres have some appealing benefits when integration into textiles is considered. Indeed, an optical fibre is in some way a monofilament and can ideally be processed like standard textile yams. The technique of hertion (knitting, weaving and stitching) of the optical fibre afterwards must be evaluated in terms of compatibility with a large volume process and compared with a “~lassical‘~ insertion into the fabric. One important task fiom the scientific and technical point of view is certainly to integrate the optical fibres with the textile during the manufacturing process. This task consists on the study of the various options for the incorporation of optical fibres into the textile together with the different options concerning the optical fibres designs. Actually, the specific characteristics of optical fibres are not particularly attractive with regards to textile fabric standard manufacturing conditions. Optical fibres are h g i l e materials which have some limits in terms of both maximal strain and minimal bending radius. As regards elongation, silica glass fibres have a limit in term on strain of about 1%. Plastic optical fibre (POF) made with polymethyhethacrylate (PMMA) have larger tolerances but show some limits in terms of curvature angles. Large curvature angles, depending on the fibre core diameter, have to be maintained during the process in order to prevent ffom permanent damage of the optical material or even fibre breakage. Finally, and once the fibre has been embedded, the m a t u r e angles should remain large enough so that the fibre keeps its guiding properties. In this case, single mode silica fibres are more attractive than POF thanksto their smaller core. On the other hand, optical fibres can also be made more robust by increasing the thickness of their external coating, or even adding an additional b d e r . However, this would be at the expense of the comfort properties of the fabric. Therefore, only fibres with an external diameter of 500 pm or less were considered. The techniques which have been tested so far are as follows.
Weaving:allowing the implementation of an orthogonal network (warp k weft threads) of optical fibres without an extensive constraint on the fibres. The design characteristics can be optimised in order to obtain the most suitable accuracy. Crochet: in order to assure contact between the sensor and the skin and a free movement without perturbation of the signal. Knittk (weft & wam knitting): in order to achieve an optimum comfort property, the knitting technology could be a solution. As it is important to have contact between the sensor and the skin and a free movement without perturbation of the signal, the knitted structure could be a solution due to the inherent properties of knitted fabrics. 466 0 Woodhead Publishing Limited, 201 0
Stitching is an alternative technique to integrate optical sensors, especially FBG, in the textile structure.
PRELIMINARY RESULTS The insertion of optical fibre into elastic and non-elastic fabrics was considered. Elastic substrates allow having a good cohesion between the patient skin and the textile where the sensor is embedded. On the other hand, non-elastic textiles may be preferred when only transmission of light is required (between the sensor and the monitoring module for instance).
Non-elastic textile fabrics Integration of an optical fibre into a woven fabric allows having a straight integration, and consequently reduced constraints on the fibre when being processed into the machine. During the first months of the project, several tests were carried out on a narrow weaving machine h m Elasta with regard to weaving silica fibres in narrow fabrics. The results were diverse. At first, it was necessary to adapt the metal rolls on which the woven structure passes, as their rough surface was found to cause numerous fibre breakages. When considering elastic woven fabrics, fibre breakages were also very fkquent because of the fabric being produced under high tension conditions. We then investigated integration on a weaving loom in a non-elastic fabric. Here, the results were more satisfying and polymer as well as silica fibres could be embedded without breakages. As a conclusion, we can say that breakage in weaving is more caused by the bending of the silica fibres(at the cross-over points ?) and not so much by the forces applied in the weaving process itself. Applying a non-elastic fabric causes less tension and thus less breakage risks.
Figure 2. Example of the integration of au optical fiber into a woven fabric.
The guiding properties of the embedded optical fibres were then assessed using a cut-back measurement set-up. Light was injected into a portion of fibre and its intensity at the output measured with respect to the length of the fibre, and the penalty in terms of attenuation was then compared between embedded and non embedded fibres.
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The figure below illustrates the impact of the coating material of the optical fibre on its resistance to the integration. From this figure, we note that the fibre with a dual polyimide coating was much less degraded by the textile integration process than the one with dual acrylate coating. Nevertheless, these results confirm that light propagation through woven textiles embedding optical fibres for the transmission of body sensors optical signals is possible, but that specific care should be given to the choice of the optical fibre. Alternatively,only short lengths (less than 1 m) of textile fabrics should be used. 7
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Elastic fabrics Because optical fibres are non-elastic materials, they can hardly be embedded into an elastic fabric structure in the same way (straight integration) as elastic yarns. This is mostly because the integration is made with the yarns being fully stretched. Therefore, new solutions have to be found out, so that while being duly maintained, the optical fibre is able to cope with the elastic properties of the fabric and does not degrade itself when elongating the textile. Meanwhile, the light transmission properties of the optical 468 0 Woodhead Publishing Limited, 201 0
fibre may be function of its position on the fabric and therefore vary with the textile elongation whenever fibre bending occurs, which can then be used for monitoring respiration movements for instance.
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Figure 5. Schematicdescription of bending effects in optical fibre. When the light encounters a bend, then a portion of the radiation is lost into the cladding, and the output power measured at the end of the fibre is lower. The tighter the bend, the more power will be lost
Evaluation of tint medical textiles containing optical fibres In this work, we are mainly interested in detecting the respiratory rate, either at the thorax or the abdomen locations. In a first step, no fine precision is required concerning the amplitude of the breathing movements, which allows focusing on a very simple scheme. We therefore developed an elastic bandage sensitive to strain and capable of monitoring patients’ movements such as respiratory motions. Preliminary samples are produced using a stitching technique, and a successful conliguration is implemented with a narrow fabric production process. The samples incorporating an optical fibre and manufactured by stitching technique have been tested using an intensity based measuring test bed. The attenuation at various wavelengths was monitored while stretching the bandage so as to simulate respiratory movements, as shown in the figure below. All experiments were carried out at a maximum strain of 3% as typical elongations of the abdominal circumferencecaused by respiratory motions range fiom 1% to 3% depending on patients, and can be below 1% for infants.
Figure 6.Experimental set-up used for testing the elastic bandages with the bending sensor
Many different fibres and stitching designs have been evaluated. Additional parameters such as the percentage of elongation and the dimensions of the loops were also varied. Finally, the amount of bending (i.e. the number of periods) was also varied, as shown on the figure below. All results are not mentioned in this document, as only the samples showing a significant loss variation would be used in the future. The most promising design was then evaluated on a human volunteer (healthy adult), and a typical trace of the sensor signal is shown below. 0 Woodhead Publishing Limited, 201 0 469
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Figure 7. Left: The design makes it possible to vary the number of periods and hence the amount of bending Right: Evaluation of the design: measurement of the respiratory activity of a human adult (healthy volunteer) using the smart textile with ihe fibreoptic sensor
Design of a “Smart Garment”
The consortium designed and developed a fust prototype of ‘intelligent garment’ based on the drawing of Institut de Technologie Medicale in Ldle (France), with a horizontal breathing sensor for the abdomen and a vertical one for the thorax. The design takes into account medical constraints in the MRI mom such as easy and rapid installation and potential need for resuscitation. Therefore, a harness-like solution that leaves the cardiac surrounding area free has been selected, as shown here below. We expect to start the evaluation of this design soon.
Figure 8. Schematic description of the smart garment for MRI use. It seems that the major diflicdty is to m a t e a harness which can guarantee a good behaviour on both thorax and abdomen, so that the movements relatingto thoracic respiration are safely detested. In addition, to make a system that fit men and women,the bandwidth of the vertical bandage must be limited.
CONCLUSIONS A new type of smart medical textile embedding optical fibres for monitoring anesthetized or sedated patients undm MRI examination is presented. Preliminary results of the behaviour of optical fibres embedded into elastic and nonelastic fabrics are given. In addition, a prehinary proof of concept of an elastic fabric capable of monitoring respiratory movements is reported. The finther development of the smart textile incorporating sensors for the acquisition of ECG, plethysmographic waveform 470 0 Woodhead Publishing Limited, 201 0
and respiratory movement parameters is currently performed within the OFSETH project.
ACKNOWLEDGMENTS
This work has received research funding from the EU 6th Framework Program under contract number IST-2004-027869. The views expressed here are those of the authors only. The Community is not liable for any use that may be made of the information contained therein.
REFERENCES 1 http://www.csem.chlsfit/htmYprojects.html 2 http://www.vivometrics.com/site/system.html
3 J L Weber, F Klefstad-Sillonville,F Pirotte. . “MERMOTH: MEdical Remote Monitoring of cloTHes”, Proceedings of pHealth - 2006 4 M F Dempsey, B Condon, ‘Thermalinjuries associated with MRI’, Clinical Radiology, 2001 56 457-65
5 http://www.ofseth.org
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INTEGRATING CONTACTLESS SENSORS FOR STRESS LEVEL MONITORING INTO CLOTHING USING CONDUCTIVE THREADS C Rotsch, D Zschenderlein, U M6hring Textile Research Institute, Thuringia Vogtland, Germany
INTRODUCTION Physical health and care are important economic factors in the 21st century with an interbranch influence. The monitoring of parameters like EMG or ECG is getting more and more important in the field of medicine, sports and occupational medicine. The integration of medical relevant sensors in textiles or clothes provides the opportunity to monitor vital parameters without influencing on wearer comfort. Many attempts have been made regarding this kind of integration of common electronic features into clothing more or less perfectly. To come to a real textile integration and textile configuration of sensors and their information transport and power supply, the CONTEXT project was initiated. The objective of the CONTEXT project is to create a system like a vest where different types of contactless sensors are integrated into textiles to be used in continuous monitoring of individuals. The contactless sensors in the vest measure the muscle activity and the psychological stress of the wearer without an influence in the ease of movement of the wearer. To realise the challenge of this project, an international team of universities, research institutes, electronics-, clothing- and application-experts work together. Different possibilities for creating conductive structures for wiring or sensor developing (printing, lamination, weaving) or the investigation of connection possibilities (embroidering, soldering, gluing) are only two points of this research project. /I/ The CONTEXTproject consortium consists of six partners: Philips ElectronicsNetherlands BV (NL) o Development of sensors, electronic components (amplifiers, filters) o Signal processing hardware and software 0 The Catholic University of Leuven (B) o Testing and assessment of sensors and sensor arrays o Developing muscle activity and stress state algorithm 0 Technical University of Berlin (D) o Miniaturizationof electronic modules o Electric interconnections of electronic modules with textile substrate, encapsulationand protection o Reliability tests of the electronicmodules 0 Clothing Plus Oy (FIN) o Definition of properties of conductive substrates and sensors o Application development Netherlands Organisationfor Applied Scientific Research - TNO (NL) o Development and determination of suitable printing techniques of conducting liquids on textile substrates o Developing conductive substrates on the basis of printing liquids on textile o Reliabilitytesting 0 Textile Research Institute Thuringia-Vogtland - TITV (D) 472 0 Woodhead Publishing Limited, 2010
o Development of conductivetextile structures and interconnects for textile ECG and EMG sensors
CONDUCTIVE THREAD MATERZALS FOR THE INTEGRATION OF TEXTILE SENSORS AND ACTUATORS
Development of conductive threads The basis for the integration of sensor- and electronicdevices in clothes is a conductive
thread material. Actual there exist different strategies and materials to create data- and energy-lines in textiles. On the one hand there are different possibilities to use common copper or steel fibres to integrate electronic parts in textiles. Some of them can be used in a regular textile process, e. g. weaving. Often there are some problems in the long term stability of these materials. If these threads were bended a lot of times they can break. On the other hand there are some tries to create conductive textile threads. They have the advantage of a very high stability against bending and the low weight. But normally it is not possible to use these structures as data-lines for low-volt signals. The resistance of these materials is often too high. Typically, these threads are used as energy-lines, e. g. for textile heating-systems. To reduce the resistance without losing the advantage of a low weight and flexibility a new galvanisation process was developed by the TITV Greiz. By different electro-chemical processes a silver-coated polyamide fibre is galvanised with a silver coating again. So it is possible to reduce the resistance of the base material from about 700-800 to 15-20 Ohms per meter (base yamcount of 235dtex). The final data depends on the type of the finishing process of the yarns. For example a different number of threads can be twisted together, so the resistance can be minimized.
Fig 1. ELITEX@ - Conductive Thread Material
Fig 2. Textile Bus Structure
These materials are designed to use in regular textile processes like weaving, knitting or embroidering. Besides they have the advantage of stretchability up to 7 % without a changing of the electric resistance. /2,3/
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Integrationof contactless sensors and developing of sensor areas The so called ELI"EX@-material (Fig. 1) is the basis for a lot of applications and products. This material and the possibilities of textile processing allow the replacement of conventional electronic materials like copper wires. This creates a much more textilelike, i.e. comfortableand drapeable fabric structure. For example it is possible to use this material to create woven bus strucmes for analogue and digital data transfer (Fig. 2) or to create energy lies. If it's necessary it's also possible to create shielded bus structures.These structures can be used to connect Werent electronic devices, like sensors or actuators. Another possibility is creating textile electrodes for sensory and actuatory applications. The objective of the CONTEXT project is to create a system where different types of contactless sensors are incorporated into textiles to be used in continuous monitoring of individuals. The integration of sensor devices in clothes is a logical choice, because people are constantly surrounded by textiles or clothing. The challenge is the exact measuring of the electromyography (and electrocatdiography)signals up to many hours especially during the moving of the wearer to make the user aware of risks due to bad posture or working conditions. By the textile charackr such measuring systems are very interesting for prevention, monitoring and treatment of RSI (=Repetitive Strain Injury Syndmm), for long term applications for example monitoring of risk patients or in the field of sports. 141 The development of special conductive thread materials for the creation of textile sensor areas and bus-structures are the main topics of the TITV Greii in the CONTEXT project. The realisation occurs by the creation of different woven multi-layer-structures. So it is for example possible to create textile capacitors, which can be used as a sensor area or insulated textile bus-structures. At that time first prototypes for a vest, textile wiring and first steps for textile sensor constructingare existing (Fig. 3).
Fig 3. First Prototype of a Vest
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Other medical applicationsusing conductivethreads Besides the sensory and diagnostic applications different types of therapy can be completed or configured more pleasant for the patient or wearer by using conductive textiles, too. Textile heating or cooling bandages complete the field of thermo therapy. The integration of analgesic or anti-inflammatory unguents in a heating bandage is conceivable, too. Another important aspect is the use and integration of textile actuator electrodes in body-near textiles, like bandages or clothing. This subject matter is an actual project of the TITV Greiz and the clinical centre of the Friedrich-Schiller-University of Jena. The selective stimulation of muscles with the new textile electrodes offers new possibilities of therapy. The complex positioning process and the fixation of the conventional electrodes can be omitted. By the easy confection of the substrate textiles with the accordant electrodes a safe and anatomic correct positioning is possible. The handling of such systems is simplified by the integration of the energy and data lines. These types of application are possible in the field of physical therapy, TENS (=Transcutanous Electronic Nerve Stimulation)and incontinencetherapy, too. The creation of textile based pharmaceutical agent depots is a further therapy application. The release of the agent can happen automatically or I and controlled. During an actual research project some textile polymer covered conductive structures are tested. It is possible to storage 50 to 500 mg acetylsalicylic acid. The amount depends on the type of finish and the material which is coated. f5I The shown examples allocate that textiles in combination with textile foreign technologies offers manifold and very interesting application possibilities for the medical diagnostic and therapy. Part of the work in the CONTEXT project is funded by the IST program of the European Commission’s 6th Framework under contract number IST-027291 (CONTEXT).
REFERENCES 1 G Langereis, L de Voogd-Claessen, A Sipilii, H Illing-Guther, A Spaepen, T Linz, ‘CONTEXT: Contactless sensors for body monitoring incorporated in textiles’, FiberMedO6: Fibrous Products in Medical and Health Care, Tampere Hall, Finland, 2006. 2 A Neudeck, Y Z h e r m a n n , J Oettel, F Thumer, S Ruppert, D Damme, A Hacke, S Scheler, U MGhring, ‘Interative textile OberiNchen - Interactive textile surfaces’, Thuringer Werhtoflag 2006, Polymere in Thuringen, Vortrdge und Poster, KGster,
Berlin, 2006. 3 S Gimpel, U M6hring, H Miiller, A Neudeck, W Scheibner, ‘The galvanic and electrochemical modljication of textiles for the integration of microsystem-technology, sensoryfunctions and electroluminescence’, Melliand - Band- und Flechtindustrie,4014 (2003)113 4 G Langereis, L de Voogd-Claessen, A Sipilii, C Rotsch, J Taelman, T Linz,
‘Contactlesssensorsfor body monitoring incorporated in textiles ’, IEEE PORTABLE, Orlando, 2007. 0 Woodhead Publishing Limited, 201 0 475
5 C Rotsch, S Hanu, A Neudeck, D Schwabe, H Oschatz, U M6hring, ‘News h m Textile Research - Special Textiles for Medicine and Medical Techniques’, Orthopdie-Technik, 2006 12 918-923.
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DESIGNING COMPRESSIVE STRETCH GARMENTS FOR IMPROVED COMFORTAND FIT P A Watkins, London College of Fashion, University of the Arts,London, UK e-mail
[email protected]
ABSTRACT The use of stretch fabrics, which apply varying degrees of compressive stretch, is becoming more significant as the benefits of comfort, mobility and shape retention, are increasingly desired for sportswear, cosmetic body shaping and medical applications. However, because of functional demands, medical garments are generally not aesthetically pleasing, do not always fit well and can be extremely uncomfortable engenderingnegative body image. Why should this be? Technical advancement in 'smart' fibres and fabrics, materials processing, virtual prototyping and manufacturing CAD solutions, each have their place in innovative design and co-operative R&D product development. Compressive stretch garment technology is, in evolutionary terms, relatively new. In 1995 Pratt and West published a manual on the design and fabrication of pressure garments to assist practitioners with the management of pressure therapy treatment However the custom fit quality is still determined by the subjective expertise of the practitioner. My passion is in the area of providing good fitting compressive stretch garments that enhance self-esteem. The Form Fit pattern, developed by the author, was not constructed by modifying the closest 'standard' pattern but from an extended body measurement set that captures body shape and proportions. As an aid to the objective evaluation of stretch fit garments a 25mm grid system has been printed on the analysis body suit. The 3D garment fit was evaluated then reverse engineered, using digital 'nip and tuck' algorithms, haptic to digital, accumulated over years of experience. The stretch garment-to-body pattern design fit was optimised through an iteration process. Adopting a parametric approach to pattern profiling enabled other variable to be considered; fabric stretch and recovery, radius of curvature and pressure implications. A true test of custom fit should be a direct correlation between the 3D body, the pattern geometry and the fabric parameters. Better fitting comfortable garments, which enhance well-being and self-esteem, will improve recovery times. This paper highlights the complexities involved in developing parametric patterns for a customised compressive stretch fit.
'.
Key Words 3D pattern profiling, pressure garment, custom fit, stretch garment analysis INTRODUCTION Stretch in garment design was originally developed for the underwear market. The commercial implications of producing welldesigned fabrics and garments to 'slenderise with less constraint' were realised and consequently form persuasive underwear was born! In medical applications form persuasive pressure is increasingly used to stimulate the healing process and as a preventative measure where reoccurrence is likely. The
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therapeutic value of pressure garments constructed using current pattern modification systems is not disputed. However, because of functional demands, medical garments are generally not aesthetically pleasing, do not always fit well and can be extremely uncomfortable, which engenders a negative sense of self, which can inhibit the healing process. The focus of my research is in further developing an objective approach to optimising the fabric stretch tensioning potential in pattern design to closely follow the body contour. Over the years, through a heuristic approach, I have intuitively overcome numerous fitting problems in stretch garment pattern design. Tacit or embedded knowledge underpins my whole approach to designing. I believed that a good fitting basic block pattern that replicates the body contour shape combined with an understanding of the behaviour of fabric stretch characteristics is an essential starting point for garment design, whatever the application.
comfort Comfort and fit are inextricably linked. Defining comfort is almost impossible because the perception of comfort is subjective. Although there is not a Universally accepted definition of comfort, it is important to recognise the main physiological and psychological factors affecting comfort. Physical comfort relates to the effect of the external elements, either physiological or psychological. It is described in The Concise Oxford Dictionary as ‘freedom from pain’ and general ‘well being’. This definition seems to be inadequate as comfort can only be described in relative terms, particularly when applied to those who often expect and endure various levels of pain. Smith suggests it is a neutral sensation most individuals find the positive sensation of comfort insignificant and have a greater awareness of the negative sensation of discomfort, which only becomes apparent when the body is adversely affected. Psychological factors are inextricably linked with physical factors in determining levels of comfort: idiosyncrasies; prejudices; preferred environment; preferred temperature;posture; pain sensitivity; effects of stress; level of embarrassment; need for privacy; body consciousness;preferred garment fit; tactile sensitivity. Textile properties including thickness and weight, fibre content and the nature of fabric structure, particularly the next-to-skin surface, are obviously crucial factors for tactile comfort4. In terms of physical comfort, a stretch knit fabric respond particularly well during movement. Mobility may be enhanced or restricted by the garment fit and how closely it conforms to the body and the pressure brought about through the tension of the retracting stretch fabric characteristics.When contoured over the body a stretch garment should fit well, and offer mobility and comfort without displacing or straining the fabric. Garment tit The term garment fit can either refer to the desigdstyle or the proximity of the garment to the body. For conventional garments the fit can be loosely interpreted but for stretch garments fit is paramount in terms of relating the garment to body contour pattern coordinates and fabric stretch parameters to determine fabric tension and predict garment pressure. For this parametric approach to pattern design, garment fit describes the proximity of the garment to the body. For clarity I have inmduced 2 anatomical terms, distal and proximal fit. Distal is away from the centre of the body and proximal is towards the epicentre of the body. On a distal proximalfit continuum the body contour becomes the zero proximal reference point 5s6.
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Garments along the distal continuum away fiom the proximal fit describe garments that are constructed from fabrics that are either non-stretch or have minimal stretch to enhance comfort. These garments are essentially an external structure ranging fiom a Loose Fit through Semi-fitted to Fitted. The proximal fit describes body-contouring garments constructed in a stretch knit fabric. The increasing positive proximal fit is related to the garment pattern stretch reduction ratio, influenced by the pressure exerted on the body, through the modulus or compressive retracting power of the stretch fabric. The zero proximal reference point or Form Fit describes garments that have few wrinkles and no tensioned stretch other than tare stretch (a minimal amount of tension) in specific areas, to allow the fabric to smoothly contour the body. The stretch fabric therefore exerts no pressure on the body and the stretch does not impede mobility. The Form Fit body suit block pattern draft co-ordinates are the key in replicating the body shape that underpins the Merent fit levels. Cling Fit, where the stretch fabric clings to the body curves, does not significantly compress or alter the body contour. Action Fit describes most sports and exercise garments where the retracting stretch effectively grips the body contour. Power Fit refers either to the gannent as a whole or to specific zones where the tensioned stretch fabric holds and compresses the flesh, changing the body form shape. Studies have been undertaken to modify patterns with a limited coverage of the body based on the extensibility of stretch knit fabrics 7-12. However the effect of stretch deformation characteristics on the pattern profile have not been considered. If the original pattern profile geometry for a conventional pattern is modified then rationalized into straight lines and fluid curves, without implicating fabric stretch deformation characteristics, which significantly alters the profile geometry in areas of arm, shoulder and breast - leg, hip, buttock and stomach, then this results in a garmentto-body fit disparity. Although stretch is accommodating, movement exacerbates fit disparities that are not always apparent when observing garments on a static body. It is the arbitrary garment-to-body fit relationship within the conventional pattern profile geometry that ultimately undermines the custom fit potential of stretch garments. The pattern profile becomes increasingly distorted as the fabric is incrementally stretched around the body contours. Anchor or grip points, which restrain the fabric, affect the fit and any movement impacts on this. Without visualising the curvilinear distortion of the stretch fabric as it contours the body, fabric stress is not always apparent, as some inconsistenciescan be absorbed within the stretch fabric parameters. Movement and skin stretch
Skin contours the body and as the body moves it stretches and distorts to accommodate movement. Skin stretch has been evaluated to determine if the behaviour is comparable to the stretch deformation characteristics of fabric when it is stretched over the body. The body can be pictured as having lines that reflect the areas of equal residual stress within the skin at rest. Surgeons take into account these stress lines when they are making incisions in the skin because wounds cut along these lines heal with the minimum of scaring. They are referred to as cleavage line orientation, or Langer’s lines, and give an indication of the orientationof skin stretch 13. Detailed studies have been made into the amount of skin stretch required by various body movements and more specifically in critical strain areas such as the back, shoulder, elbow, seat and knee, where the maximum stress is exerted on garments during activity.
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During research carried out for W o n t in America, Kirk and Ibrahim14, as part of a larger study, observed skin stretch and fabric stretch, to ascertain a relationship, which could then be applied to garments. A series of linear markings were drawn on the straight knee as the knee moved fiom straight to bent the skin stretch was measured. It was found that the maximum lateral skin strain occurred at about one inch above the knee and not at the centre. They found that the fabric characteristics over the knee in a stretch garment, when it is restrained around the waist and underneath the foot, perform in a similar way to that of the skin. Mecheel and et al.’* produced a key, showing the degree of skin stretch brought about by basic movement over the whole body.
GARMENT PRESSURE RESEARCH LITERATURE H a n d 6 explored the relationship between the degree of skin stretch and the degree of fabric stretch in conjunction with the proximity of the garment to the body. They utilised Laplace’ Law to relate to clothing pressure, which is brought about through the radius of the human curved surface. This approach was to determine how closely the fabric should conform to the body for optimum comfort levels. Laplace Law Laplace’ Law relates pressure, tension and radius of curvature in the following way: P = T/p Where ‘P’ is the pressure exerted on the body. ‘T’ is the tension of the fabric, which is dependent on stretch parameters, and ‘p’ is the radius of the curved surface of the body. Assuming that the degree of fabric stretch is maintained at a constant level, the tension in the fabric will remain constant. A key variable affecting the pressure of the fabric on the body is therefore the radius of the part being covered, the smaller the curve the higher the exerted pressure. The implication of this is that the amount of pressure applied along the leg, for example, would not be linear. Parts with smaller radii (for example ankles, wrists) require less reduction in the fabric to achieve the same garmentto- body interface pressure. Compression measurement The main body of research for measuring pressure garment products is for medical application. External pressure is used in the treatment of an ever-broadening range of medical conditions. Some examples are;management of venous insufficiency,reduction of hypertrophic scarring, management of lymphedema, promote wound healing and prevent or manage oedema after medical procedures, prevention of skin-waves af€er liposuction, and in conditions where sensory information is impaired such as in a stroke or sensory integration disorders. Studies”-I9determined the levels of pressure required in garments of the type used to reduce the hypertrophic scarring of bums victims. was undertaken to evaluate the degree and position of compression needed to attain an optimum effectiveness for compressive bandages, and elastic stockings. In 1995 Pratt and West published a text on the design and fabrication of pressure garments to assist practitioners with the management pressure therapy treatment. The manual suggest Lycra fabrics of a given weight and extensibility typically used in the manufacture of garments. They devised a mathematical formula for pattern drafting. Basically all circumferential measurements are reduced by 20% and length measurements are reduced typically by 20% -25 % of their total length. But they go on to state that 480 0 Woodhead Publishing Limited, 2010
applying the formula is not straightforward and needs subjective adjustment based on experience’. Research Studies, other than for medical purposes, to ascertain acceptance levels of pressure exerted on specific areas of the body, by the fit of different garments, have been conducted. Ibrahim2’ undertook an investigation into the “Mechanics of FormPersuasive Garments Based on Spandex Fibers” at the Textile Research Laboratory of W o n t in America The research was to gain an understanding of the functionality of form-persuasive garments in relation to fabric performance parameters, to provide a proper basis for design. Japanese researchers Horino et al.% studied the simulation of garment pressure in wear. S h ~ evaluated h ~ ~ acceptable comfort pressure levels of men’s socks using elastic optical fibre. In Britain tests developed by Clulow 28 at the Shirley Institute - now re-named the British Textile Technology Group (BTTG) - were carried out to measure acceptable levels of pressure for comfort of waistbands, sock-tops etc. More recently Marks 62 Spencer, as part of their fit testing, introduced a bra sensor to ascertain the pressure exerted at specific sights on the body, including the shoulder area and around the rib cage. Yu outlined in Fan et al?9 the development a soft mannequin, simulating the skeletal frame, soft body tissues and skin of the lower torso of a female, to measure the contact pressure of legless pants. This enabled the correlation of garment pressure, through the use of a linier equation, to be predicted on live models. Research literature summary The research addressed three areas: 0 The fabric stretch extensibility was assessed from a textile technologist’s perspective. 0 Patterns were produced taking a conventional rationale as a starting point and were then adapted. 0 Body to garment interface pressure was measured at specific sites or areas. The basis of most research is that the fabric tension and the radius of the human curved surface determine garment pressure. In the pattern construction the suggested reduction of circumferences by 20% and overall length reductions of 20%-25% seems to be typical, Most research was carried out using simulated body circumferences to actual body zones. An objective approach to garment pattern design encompassing body shape and mobility around the multi-axial torso limb junctions of the shoulder and hip was not outlined. The lack of correlation between the 3D body profile and the 2D pattern geometry contouring the whole body, combined with the application of arbitrary stretch fabric parameters in the pattern reduction process, severely Limits the objective evaluation of garment-to-body interface pressure variables over the whole of the body. It is difficult to evaluate and predict garment pressure consistently over the whole body contour if research is confined to a limited area only. Assessing Stretch Extension Stretch fabrics for medical applications are produced in a range of fibre content and weights with differing stretch extension capabilities. Information on stretch fabrics and the way stretch extension is quantified in the process of constructing a stretch pattern is not straightforward. British Standard3’ ‘Determination of the elasticity of fabrics’ are used by fabric and fibre producers and garment technologist to assess the fitness for purpose of a garment fabric and have specific quality assurance parameters in common. 0 Woodhead Publishing Limited, 201 0 481
Electronic tensile testing instruments as used in most research is not generally available to the occupational therapist. The appropriateness of this type of instrument for pattern development of pressure garment products to date has not been considered. Although manufacturers suggested fabric extension rates follow industry standards, variations in fabric stretch within the production cycle need to be quantified for pattern reduction. A simple device is required to measure the degree of fabric extension objectively, which would allow pressure zoning to be incorporated in the pattern design. The development of consistent and verifiable test methods resulting in industry standards has engendered its own common language between fabric and garment technologists. The same level of integration between stretch fabric producedtechnologists and pattern technologistddesigners is needed to introduce objectivity into stretch pattern technology. Pressure Garment Fit Although extensive research has been undertaken into optimising the level of pressure brought about the tensioned fabric of pressure garments, custom fit is still dependent on subjectiveexpertise and haptic fit manipulation of fabric tension. Pratt and West state in their manual-
In some instances, measurements have to be altered ‘by eye’ or judgement alone. For example, when fitting a sleeve into a vest, a measurement is taken h m the mid-axilla to the base of the lateral aspect of the neck The angle at which this is drawn on the pattern will rely on your observations of the shoulder’s girth, the patient’s postural patterns and the site of the scarring. (I P24) TRADITIONAL PATTERN DESIGN AND MOBILITY
The analysis of traditional garment pattern design and fit for non-stretch fabrics, the method and the rational can stimulate imaginative solutions to enhance movement in pressure garment pattern design. However in a conventional stretch bodysuit poor fit is not always apparent visually until the garment has been worn and washed several times. The fabric may then be ‘n to degrade at the underarm and body rise or the seam stitching bursts. Watkins outlines an objective approach to visually evaluating stretch fit. Movement can be enhanced or inhibited by the garment fit particularly problematic are the shoulder and hip areas. Joints can be classified by the extent of their range of movement. The shoulder is a multi-axial joint that has the highest degree of mobility. The body area commentaries following highlight a way in which a rigid pattern can be developed to assist the shoulder to move freely.
w
The Bodice
The crucial areas for fit in the bodice are the shoulder angle, the breast and the armscye (armhole). The conventional block pattern for a bodice (see Fig 1) shows the intended relationship between the garment pattern and the torso.
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Fig. 1. Conventional bodice block pattern and torso. Shoben and Ward= p39
The Shoulder Angle The shoulder angle is determined by posture and elevation of the shoulders and has a significant influence on the fit and comfort of a garment. H u t ~ h i n s o noutlines ~~ a method for determining the shoulder seam placement using a frame to measure the shoulder angle, however, the technique uses complex equipment that is not readily available. R o p 4 explains how to achieve an accurate shoulder angle by taking three simple measurements. These co-ordinates combined in the pattern draft give an accurate shoulder angle for the subject’s body posture when applied to both front and back bodice constructions.
The Set-in Sleeve For a conventional set in sleeve, the sleeve crown (height and shape at the head of the sleeve) reflects the shape of the top of the arm when hanging in a relaxed position by the side of the body (see Fig 2). The sleeve torso angle relationship affects the degree of fieedom of arm movement. The set-in sleeve fit is at its best when the arm is fully adducted with the fabric at the crown conforming smoothly around the top of the arm. Movement becomes restricted when raising the arm away from the body (see Fig 3).
Fig 2. Set-in sleeve pattern and torso Shoben and Ward3* p40
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Fig 3. Set-in sleeve and mobilrty Pivnick= p58
When a set in sleeve is constructed in stretch fabric movement is restricted, as it is impossible to lift up the arm without the fabric Straining. A prime example that many will be familiar with, which illustrates the point, is the cling fit stretch T-shirt with this conventional sleeve construction. When the arm is raised, the fabric adjusts to the new body position and the underarm seam, if it is lower than the natural armscye line, the underarm sleeve junction will automatically reposition at the anchor or grip point under the arm. Subsequently when the arm is lowered a fold of fabric (producing the effect of an unwanted shoulder pad) appears at the apex of the sleeve crown. A fold of fabric also appears across the chest above the breasts. The T-shirt mmfort/fit factor is only maintained by constant rearrangement after movement. LaI3at and D e L ~ n concluded g~~ that poor fit can lead to a negative body cathexis but it is the pattern profile geometry that is at fault and not the inadequacy of the wecirer’s bodyshape. Inappropriate pattern geometry in combination with the fabric stretch does not allow the crown to resume its original position when the arm is lowered.
T h e shirt Conventional shirt-sleeve pattern construction allows the arms to be raised and move k l y . However, it can be observed (see Fig 4) that when the arm is lowered, diagonal wrinkles form towards the under arm. In the illustration (see Fig 5) the shirt-sleeve profile (solid line) is achieved by slashing and spreadingthe set-in sleeve pattern (dotted line). As the width of the sleeve increases, the underarm is lengthened and the crown becomes shallower, allowing the wearer to move with ease. In a stretch pattern, if the crown pattern geometry retains a similar profile to the conventional set-in sleeve pattern, with little change in the crown depth, this impairs the quality of the garment fit. When a crown pattern profile similar to a shirt is drafted in a stretch pattern, the width of the lower sleeve may rernain m o w with increased width between the underarm seam junctions. This allows the arm to move freely without fabric displacement after movement.
Fig 4. Shirtsleeve. Ladbu$’
p i 07
Fig 5. Pattern manipulation.
Pivnick= p58
PROXIMAL FIT PATTERN DESIGN The shape of the fabric affects the stretch characteristics.A visual understanding of the overall stretch curvilinear fabric distortion characteristics is essential to the process of pattern production through garment fit analysis and evaluation. Evaluation of the stretch deformation of various shapes, printed with a grid pattern and stretched, such as rectangles, trapezoids and triangles can contributeto maximising the stretch garment fit
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potential in the pattern design. The area of the shoulder angle, armscye, sleeve crown and the protrusion of the breasts illustrates where directional change and protrusion need an integrational approach balancing the pattern profile with the deformable fabric geometry for the range of movement required. The transposition of the sample shape deformation of a triangle or trapezoid is informative when applied to the garment pattern for the sleeve crown.
The Dynamic Crown Angle The alignment of the arm to the body determines the basic shape of the sleeve pattern and the armscye intersection of the bodice pattern. By manipulating the pattern geometry a range of movement to be performed by the arm can be accommodated. For the proximal fit pattern profile I have introduced The Dynamic Crown Angle that relates to the depth of the crown, which is calculated fIom the shoulder point at the top of the crown to the intersection between the arm and chest. This depth becomes shallower as the geometry of the pattern profile changes to utilise the fabric stretch characteristics to enhance the fit quality and accommodate a range of movements. Figures 6 and 7 illustrate the bodice to sleeve angle relationship and the shallow crown shape in the bodysuit analysis garment, which approximates a subject standing with the arms abducted at 45".
Fig 6. Analysis bodysuit 25mm grid - Front
Fig 7.Analysis bodysuit 25mm grid - Back
Proximal form fit The geometry of the stretch block pattern profile can only be developed successfully through understanding the complex relationship between the dynamic form, the stretch fabric behaviour and the two dimensional pattern profile geometry. My approach to pattern design has been analysing traditional procedures in pattern design and garment fit to accommodate different bodyshapes, posture and movements. The 3D garment fit is evaluated then reverse engineered, using nip and tuck algorithms (haptic garment fitting experience accumulated over years) translated into digital form, and then re-applied to the evolving 2D pattern pieces. Replicating the sue and shape of a person in the pattern profile is the key. Good fit is dependent on the pattern draRing co-ordinates cooperating with the stretch characteristics conforming to the shape of a person. My research has enabled me to develop a Form Fit block pattern using a personally extended set of traditional measurements. The new Form Fit block pattern is the basis for developing both distal and proximal garment fit. Producing a form fit flat pattern, Without darts that closely adheres to the contours of the body without restricting 0 Woodhead Publishing Limited, 201 0 485
movement, is complex. In woven fabric, darts and ease are used to manipulate the fabric around the form and allow movement. In a knit stretch garment without darts to contour the body, a degree of fabric stretch distortion (tare stretch) in areas of protrusion is inevitable. An optimised contour fit pattem should produce a garment that has no wrinkles, minimal stretch distortion and conforms to the body, rather like a second skin.
Proximal action fit To produce the Action Fit the algorithms for the Form Fit patterns are enhanced to take into account the selected fabric stretch characteristics,the desired fit level and the radius of cwature, which can vary for adults and children or for different body zones. The resulting parametric pattern produces an Action Fit stretch bodysuit that is a true custom fit for the selected body shape size, fit level and chosen fabric. Objective fit malysie Pressure garment fit encompasses a complex set of variables. It is difficult to visualize and quantify the garment-to-body stretch fabric tensional parameters when altering the garment in the manual fitting process. The quality of the fit becomes dependant on the subjective expertise of the fitter. Therefore to objectively evaluate the fit a 25mm grid system has been printed on the analysis body suit. The stretch garment-to-body pattern design fit is optimised through an iteration process. A grid system allows the designer to visualise stretch deformation over the body contours. The grid pattern deforms into different geometric shapes indicating; garment to body alignment and the amount and direction of fabric stretch. Gridlines not only enable the observer to identie areas of unacceptable stretch, which is indicative of the pattern profile being incorrect, but also they confirm that the horizontal and vertical toile/body placement aligns as the designer intended. Movement fit analysis The fit relationship is complex and a more representativeevaluation is conducted on a subject rather than a dress stand. The assessment takes place after the garment has warmed up and a series of movements, which l l l y articulate the body and the fabric, have been performed. Body heat affects the fibres in fabric causing them to relax and mould to the body. On cessation of movement the fabric adjusts to reach equilibrium in contouring the body. As can be observed in figure 8 the fit is not displaced during movement.
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SUMMARY Garment pressure is brought about by the fabric tensional stretch over the radii of the human curved surface. The circumferential shape and body mass distribution of hard and soft tissue (which can change during movement) effects garment pressure. The qualification of optimum garment tension and garment to body interface pressure values is difficult to assess and predict if fabric extension rates are arbitrary and the pattern rationale does not meet the dynamics of the individuals body contour fit requirement. Uneven stretch distribution is not visually apparent without analysing the garment-to body curvilinear stretch distortion characteristics.Therefore the quality of the custom fit impacting on pressure levels is dependent on arbitrary factors and the subjective expertise of the specialist fitter. It may be argued that because of the increasing sophistication of virtual technology garment pressure mapping should be confined to the virtual realm. But fiom the perspective of a designer the starting point is building on craft skills to understand and articulate the technical processes. The design ideation process is cyclical in analysis evaluation and application. Sound objective methodologies integrated with new technology will enhance pressure garment design for either manual or computerised production. A true test of custom proximal fit should be a direct correlation between the 3D body contour requirements, the pattern geometry and the fabric stretch parameters. The compressive stretch fit can be analysed through the introduction of technologically advanced stretch fabrics, which detect small changes in pressure that can be visually represented in a body map. The optimal garment pressure fit distribution for a given application could then be predicted. These factors with the addition of determinants for comfort and fieedom in a dynamic CAD/CAM technology have exciting implications for M e r research.
REFERENCES 1 J Pratt and G West, Pressure Garments a Manual on their Design and Fabrication, Oxford Butterworth Heinemann Ltd 1995. 2 The Concise Oxford Dictionary 1980. 3 J E Smith, ‘The comfort of clothing’, Textiles, 1986 lyl) 23-27. 4 P Harnett, ‘Functions and properties of ‘thermal‘underwear’, Wool Science Review, 1976 5240(1) 3-11. 5 P A Watkins, ‘Custom fit pressure garment pattern profiling’, Int Conf Wearable Futures: Hybrid Culture in the Design and Development of Sop Technology, University of Wales, September 2005.
6 P A Watkins, ‘Custom Fit, Is it FIT for the Customer?’ 8” Annual IFFTI Conf Fashion in the Digital Age, Raleigh, North Carolina,USA. June 20-22,2006,
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7 T Kirstein, S Krzywinski and H Rodel, ‘Pattern construction for closefitting garments made of knitted fabrics’, Melliand Textilberichte, 1999 80(3) E46-48/146-148.
8 B Ziegert and G Keil, ‘Stretch fabric interaction with action wearables: defining a body contouring pattern system’, Clothing and TextilesRes J, 1988 6(4) 54-64. 9 Bonuigheim Passformsicherheit fur Bodies und mehr. Bekleidung, 1996 21 29. 10 J Chun and J H Hue, ‘Development of bodice patterns modifications system based on the stretch rate of knit’, ZT’ Proceedings, USA, 1998 110-111.
1 1 H Rodel, A Schenk, C Hmberg and S Krzywinski,Int J of Clothing Sci and Tech, 2001 13(3/4)217 - 227.
12 S Krzywinski, H Rodel and J Siegmund, ‘Virtualproduct development for closefitting garments of knitwear with elastau yarns’, 2& Int C o d Textile Research Division, NRC, Cairo, Egypt April 11-13,2005. 13 N Palastanga, D Field, and R Soames, Anatomy and Human Movement: Structure and Function, London, Butterworth Heinemann, 1989.
14 W Kirk and S M Ibrahim, ‘Fundamental relationship of fabric extensibility to anthropmetric requirements and garment performance’, Textile Res 4 1966 36(1) 3747. 15 J Mecheel, Krafte an Textilien und Nahten der Kleidung in Abhaugigkeit von Korperbewegundund Kleidungschnitt, 1980.p33.
16 T Harada, ‘Pursuit of comfort in sportswear,J7N, 1982 pt.334,September, 30-33. 17 H P Giele, K Liddiard, K Currie and F M Wood,‘Direct measurement of cutaneous pressures generated by pressure garments’, Bums in WesternAustralia Research Group International Symposiumfor Hypertrophic Scar, Hong Kong, June, pp. 1-51995. 18 Ng S-F, F. ‘Design of pressure garments’, Ph.D, De Montfort University, Leicester, September 1 995.
19 L Macintyre, M Baird and P Weedall, ‘The study of pressure delivery for hypertrophic scar treatment’, In?J o f ClothingSci and Tech, 2004 16(1/2) 173-183. 20 P H Fentem and M Goddard, ‘Comparison of a direct and an indirect method of measuring hosiery compression’, Jof the Textile Ins?,1979 7q5) 198-209. 21 J Homer, L C Lowth and A N Nicolaides, ‘A pressure profile for elastic stockings’, British Medical J, 1980 280 818-820.
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22 P H Fentem, ‘Advances in elastic hosiery’, Pharmacy Upate, 1986(5) 200-205. 23 V N Filatov, ‘Planning and evaluation of elastic fabrics for medical applications’, World Textile Abstracts, 1985 14(1) 45-52.
24 E Maklewska, A Nawrocki, J Ledwon and K Kowalski, ‘Modelling and designing of knitted products used in compressive therapy fibres & Textiles in EastemEurope’, Januaryhlecember 2006 14, no. 5 (59) 1 1 1-1 13. 25 S M Ibrahim, ‘Mechanics of form-persuasive garments based on spandex fibers’, Textile Res J, 1968 950-963. 26 T Horino, S Kawanishi and M Toshimi, ‘Simulation of garment pressure in wear by strip bi-axial extension of cylindrically sewn fabrics’, J of the Textile Machinery Society ofJapan, 1977 23(2) 41-46. 27 K Shoh,’Comfort pressure evaluation of men’s socks using an elastic optical fiber’, Textile Res J, 1998 68(6) 4 3 5 4 0 . 28 M Sawbridge, ‘Comfort of clothing’, New Home Economics, 1989 35(9) 5-7. 29 J Fan, W Yu, and L Hunter, Clothing Appearance and Fit: Science and Technology, Cambridge: Woodhead Publishing 2004. 30 British Standard BS EN 14704-1:2005 Determinationof the elasticity of fabrics, UK, British Standards Institute, April 2005. 31 P A Watkins, ‘Analysis of stretch Garments’, Textile Institute 80th World Conference, Manchester, April 2000. 32 M Shoben and J Ward,Pattern Cutting and Making Up: The Professional Approach 1 Basic Techniques and Sample Development, London, Batsford Academic and Educational Ltd. 1980. 33 R Hutchinson, ‘The geometrical requirements of patterns for women’s garments to achieve satisfactory fit. (T16351)’, M.Phi1, Department of Textile Industries University of Leeds, 1977 September.
34 M Rohr, Pattern Drafting and Grading, 2nd Ed Eastchester, New York, M. Rohr. 1957. 35 E K Pivnick, Fundamentals of Patternmakingfor Women’s Apparel Part 2, 3rd Ed New York, Pattern Publications 1958.
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36 K L LaBat and M R DeLong, ‘Body cathexis aad satisfation with fit of apparel’, Clothing and Textiles Res J, 1990 s(2) 43-48. 37 A Ladbury, Dressmaking with Liberty, London, Guild Publishing 1984.
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BURN HAZARD POTENTLAL,PREIGNITION AND POSTIGNITION THERMALPROPERTIES OF TEXTILES A W Kolhatkar' and P C Patel' 'Department of Textile Engineering, J D Institute of Eng & Technology, MIDC,Lohara, Yavatrnal, Maharashtra India 'Department of Textile Engineering, Faculty of Technology tEng, M S University of Baroda, Varodara,Gujrat, India
ABSTRACT The paper compares the comprehensive study undertaken for pmignition and post-ignition thermal properties. Accordingly a specific equipment has been developed namely, Bum Hazard Potentiality Tester (BHPT) to measure the pre-ignition and post-ignition at different angles of testing. It works on measurement of incident heat fluxes released during burning of a particular fabric. It also provides the real fire situation, where the skin is exposed to the incident heat released during the burning of the fabric. The paper shows contradictory results in case of pre-ignition and post- ignition thermal properties and reveals that post ignition measured thermal properties play a major role in determination of hazard potentiality of textiles.
Key words: Average Incident Heat Flux, Flammability, Ignition Time INTRODUCTION Testing the flammability of a material includes the measurement of various pre-ignition and post-ignition properties as per the different flammability standards across the globe pre and post ignition properties are important for testing, to avoid the risk of bum hazard.'-3 Ignition is the initiation of combustion, flame spread is the movement of the flame across the specimen, and heat release refers to the amount of energy released during the combustion process. Here it is attempted to study these properties and correlate to the risk of hazard.
MATERIALS AND METHODS Two different woven (saree) fhbric specimen fabrics of different fibre type were selected viz. cotton and polyester. Five different supporting garment fabrics i.e. two types of (petticoat) fabrics of cotton, three types of (blouse) fabrics of cotton, polyester: cotton (67:33) blend and polyester fabric were also selected. Two knitted fabrics of cotton for bra and underwear were also selected. Each fabric is given sample code for (saree) fabric specimen, petticoat fabric light (PL), bra fabric (s) and underwear fabric 0 . T h e average values of ten replicates for each of these parameters viz. gsm, ends per inch, picks per inch and air permeability of cach sample is given in Table 1.1 and all were tested as per the combinations of the fabric specimen and supporting garment on the body particular to wearing of saree and its supporting garments.
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Table 1.1 Specificationsof fabrics used for the burning behaviour Study
Sr. No.
FibreType (Blend Ratio)
Fabric Mass
1 2 3 4 5 6 7 8
Nylon P:C 5050 P:V 5050 Polyester Cotton Polyester Cotton Cotton
gm 60 75 71 55.3 53.1 63 98 130
9
Cotton
130
* Knitted fabric
'lkadcount Ends/ inch 99 100 95 89 72 63 98
-
-
Picksl inch 70 70 65 60 60 106 90
Air Perme ability cc/cmz cc/cm' Is 95.21 302.13 142.1 101.21 363.21 140 97.97 60
Applicat ion Of code fabric
Saree Saree Saree Saree Saree Blouse Petticoat
Bra* Under Wear*
SAI SA8 SA9 SA6 SA7 B(P) PL B
All the samples are tested on a newly developed instrumentnamely; Bum Hazard Potential Tester (BHPT). The operating principle of BHPT is based on measurement of incident heat flux released during burning of fabric sample. The tester mainly measures incident heat, released during the burning of the fabric sample. This provides the real fire situation (insitu condition) where the skin is exposed to the incident heat released during the burning of the fabric. The BHPT was designed to allow small samples of fabric to be tested for determining their relevant thermal properties. The flammability of a fabric can be measured in terms of both pre-ignition and post-ignition characteristicssuch as: i) Time for ignition ii) Flame propagation rate iii) Burning rate Heat release rate during burning iv) The test is designed such that individual samples could be tested separately, or combined into assembly. A constant heat flux level is used to ignite the fabric sample. The liquid petroleum gas is used as fuel for the flame to burn the test specimen.
RESULTS AND DISCUSSION The time required to ignite a particular specimen shows the ease of ignition of a particular specimen. Accidentally, if the fabric encounters the flame within few seconds the fabric will ignite, depending upon the energy for reaching its flash point and ignition kmperature. The major objective of the fabric ignition studies is to determine the time duration required by any particular combination of Fabric specimen to reach its flash point and ignition. This period shows the ease of ignition of particular combination of temperature. The major objective of the fabric ignition studies is to determine the time duration required by any
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particular combination of Fabric specimen to reach its flash point and ignition. This period shows the ease of ignition of particular combination of Table 1.2 T,, values for different combinations Fabric specimenCode SA1 SA6 SA7 SA8 SA9 Material combinations N P C pic p/v 100 100 100 50/50 50/50 blend SA 2.8 2.2 1 1.5 1.7 8SA 4.4 4.1 2 3 3.1 €3 (PI 1.8 1.8 1.8 1.8 1.8 B(P)+SA 3.4 3.2 1.3 2 2.1 B ( P + 8 SA 4.3 4 2 2.8 3 B + B (P)+SA 3.7 3.4 1.8 2.7 2.9 B+B(P)+ISA 4.5 4.2 2.3 2.9 3.2 PL+2 SA 3.5 3.3 1.4 2.2 2.3 PL+3 SA 4 3.7 1.6 2.7 2.8 PL+10 SA 4.5 4.1 2.4 3.2 3.1 UV+PL+2SA 4.1 3.8 1.4 2.7 2.8 UV+PL+3SA 4.2 3.9 1.7 2.8 2.9 UV+PL+IOSA 4.5 4.1 2.5 3.3 3.4 SAl+PL+3SA 3.8 3.6 1.6 2.4 2.5 Fabric specimenRank 1 2 5 4 3 (Ignition) Table 1.3 AIHF 60 values for all combinations Combin&m
Tatangle 1SA 8SA
Nylon 45 086 292 121 I41 504
SA B+B(P)+SSA PL+ZSA PL+3SA PL+ lOSA
UV+PL+;ZSA UV+PL+JSA W+PL+I@A 2SA+PL+3SA
203 640 221 252 621 370 432 700 430
P 100% 45 I47 424 121 I87 458 290 606 2 70 384 563 399 3 91 6 16 477
C 100%
45 051 508 121 320 523 350 642 300 357 586 422 5 04 625 442
P/C50/50 45 I32 4 12 121 380 408 255 621 283 335 581 375 420 620 390
PIV50150 45 120 5 23 I21 I72 5 97 3 89 7 19 2 47 2 73 7 35 3 95 4 30 8 06 421
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Nylon 90
I12 382 246 I86 560 257 780 3 32 3 54 687 387 443 I16 435
P 100% 90 204 469 246 3 19 489 342 644 394 4 10 5.71 439 488 678 524
C 100% 90 057 531 246 440 556 384 683 322 3 80 684 452 538 638 465
PIC50150 90 203 495 246 423 456 345 720 348 348 598 160 479 651 465
PIV50 S O
90 I 69 5 80 2 46 2 15 681 4 04 7 60 2 98 3 13 8 14 4 30 4 70 9 16 5 06
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fabric specimen,when it is exposed to a flame. Depending upon the span of time, the safety of combination would be considered for instant rescue from the fire. Thur, the ignition time is used as a tool to rank the Fabric specimen fabrics for their ignitability in most of the flammability tests. Table 1.2 shows the average values of 10 replicates of the samples tested at 90" test and it is expressed as Tig in seconds, (time duration for ignition) for all Fabric specimencombinations. The time for ignition (Ti& indicates that, single layer nylon Fabric specimen takes longest time to ignite at 2.8 s, where as cotton takes 1.0 s to ignite. Among the otherFabric specimen,P:C 5050 blend takes 1.5 s. P:V 5050 blend takes 1.7 s, and p takes 2.2 s. The results revels that time for ignition depends upon the time required by fibres to reach its ignition temperature at a mnstant heat flux, as cotton ignites at 406C it is first to ignite and as nylon ignites at 532' C it is. lastly ignited among all the samples. The ignition temperature of polyester is 450C, which requires more time to reach the ignition temperature than cotton with lower ignition temperature4. nus,the time for ignition of polyester: cotton blended fabric needomoretime to ignite than cotton fabric. Similarly the ignition temperatm of viscose is 420 C and polyester is 450' C, which delays the time for ignition for polyester: viscose blend as compared to viscose fabric. It can also be seen that time for ignition of a particular specimen, depends on the mass and proportion of material in sandwich layers. When cotton Fabric specimen in two layers, three layers and ten layers is tested along with light petticoat, the Tig values of Fabric specimen increase as the layers increases showing difficulty to reach the ignition temperature due to increase in layers and there by increase in mass at a given area. The same trend is observed for all Fabric specimen material as seen from Table 1.2 Average incident heat flux studies show dissimilar results and ranking of fabric (saree) along with the supporting garments. As the buminjuries are due to incident heat fluxes on the skin, increase in the average incident heat flux, increases the severity and higher will be the degree of bum. Accordingly, cotton saree show least average incident heat flux and ranks first in safety followed by nylon, polyester: viscose (50:50), polyester: cotton (5050) and polyester. Compared to the approach of ignition studies (as it is used in most flammability test parameters across the world and even used in this study) and heat flux, for ranking of safety of saree, heat flux study is more logical and practical, because safety just camot be ranked on the basis of possibility of catching fire of garment. But it should be based on actual heat absorbed by the human skin during the burning of garment and thus this study supports and recommends the ranking of (saree) as per the heat flux approach. Nylon: Ignition studies & AIHF studies The analysis of ignition studies on nylon Fabric specimen along with supporting garments reveals that, the Fabric specimen can be easily ignited fiom its various combinations at minimum 2.8 s and maximum at 4.5s. The results show an ease of ignition at single layer and difficulty at multiple layers, time for ignition of nylon Fabric specimen depends not only upon the material but also on the number of layers to be ignited. Nylon Fabric specimensingle layer easily ignites at 2.8 s where as with eight layers it ignites at 4.4 s. It was found from Table 1.3 that, when nylon Fabric specimen is testedo with diqerent combinations, the AIHF is maximum 7.20 and 8.16 caVcm2s at 45 and 90 test respectively, for the UV+PL+IOSAl combination,where the total gsm is 828. Whereas for
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the B+oB(F') +8SA1 combination with 673 gsm, the AIHF is 6.40 and 7.80 caWcm2s at 45O and 90 test respectively. The minimum AIHF value is at SAl and is 0.86-1.12 cal/cm2s. The number of hydrogen and carbon atoms available in 828 gsm sample is more than that at 673 gsm sample, the nylon material have 34 carbon hydrogen atoms and 20 Carbon hydrogen bonds in a single unit, possessing bond energy of around 413 Wlmol per GH bond. Due to addition of nylon layers with cotton layers more amount of hydrocarbons are available for oxidation as compared to the othercombmation. More the proportion of strong bonds more will be the energy required for formation and dissociation of these bonds and more will be the energy liberated during their buming exothermic reaction, It can be seen from the Table 1.3 that the AlHF increases, when polyester blouse is burnt with single layer Fabric specimen and eight layer Fabric specimen along with cotton bra. The AIHF values increases from 0.861.12 caWcm's at single Fabric specimen combination to 1.41-1.86 caVcm2s at B(P)+SAl combination. The AIT-IF values also increases from 2.92-3.82 caWcm's at 8SA1 to 5.04-5.60 caWcm2s at B(P)+ISAl combination. This rise in AIHF values signifies that polyester blouse significantly increases the AIHF values. Polyester: Ignition studies & AIHF studies The analyses of ignition studies on polyester Fabric specimen reveals that, the Fabric specimen can be easily ignited from its various combinations at maximum 4.3 s and minimum 1.4 s, showing ease of ignition at single layer and difficulty at multiple layers The ignition studies also reveal that time for ignition depends upon not only the material but also on the number of layers to be ignited. Polyester Fabric specimen single layer easily ignites at 2.2 s where as with its 8 layers ignites at 4.1 s. It was found fiom Table 1.3 that, when polyester Fabric specimen is tested with different combinations, the AIHF isommaximumat B+B(P)+8SA6 combination. The AIHF is 9.06 and 9.44 cal/cm2sat 45' and 90 tests respectively and the gsm is 633. Where as for the UV+PL+lOSA6 combination with maximum 778 gsm, the AlHF is 7.62 and 8.09 cal/cm2s at 45' and 90' tests respectively. The minimum AlHF value is at combination S(P) is 2.04 caWcm's. The number of hydrogen and carbon atoms available in 633 gsm is more due to presence of polyester than that at 778 gsm, even though the mass of the sample is less. More the proportion of strong hydrocarbon bonds more will be the energy required for formation and dissociation of these bonds and more will be the energy liberated during this burning exothermic reaction. It can be seen Eom the Table 1.3 that polyester blouse increases the AJHT values, when it is burnt with single layer and eight layer Fabric specimen along with cotton bra. The AlHF values increases from 1.47-2.04 caVcm's at single Fabric specimen combination to 1.87-3.19 cal/cm2s at B(P)+SA6 Combination. The AIHF values also increases from 4.244.69 cal/cm2s at 8SA6 combination to 4.58489 cal/cm2sat B(PP8SA6 combination. This rise in AIHF values signifies that polyester blouse significantly increases the AMF values. It is found that as the number of polyester Fabric specimen layers increases, gsm increases which in turn increases the AIHF value. From the above observations it is seen that even in all the cases of polyester Fabric specimen combinations the maximum AMF occurred at 90" test as compared to 45'.
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Cotton: Ignition studies & AJEF studies The analyses of ignition studies on cotton Fabric specimen reveals that, cotton Fabric specimentemperature. The major objective of the fabric ignition studies is to determine the time duration required by any particular combinationof Fabric specimen to reach its flash point and ignition. This period shows the ease of ignition of particular combination ofn can be easily ignited h m its various combinations at maximum 2.3 s and minimum 1 s, showing ease of ignition at single layer and difficulty at multiple layers. The ignition studies also reveals that time for ignition depends upon not only the material but also the number of layers to be ignited. Cotton Fabric specimen single layer easily ignites at 1 s where as with its 8 layersit ignites at 2 s. The ignition time of polyester increases from 1.4 s to 1.5 s, when it is burned with petticoat fabric. It was found from Table 1.3 that, when cotton Fabric s cimen is tested with different combinations, the AIHF is maximum 6.25 and 6.38 c d c m s at 45’ and 90’test respectively for the W+PL+lOSA7 combination, where the total gsm is 758. Where as for the B+P(P) +8SA7 combinationwith 617 gsm the AIHF is 6.42 and 6.83 cdcm’s at 45’ and 90 test respectively. The minimum AMF value is 0.51-0.57 caVcm2s at combination 1SA7. The number of hydrogen and carbon atoms available in 758 gsm is more than that at 6 17 gsm. It can be seen that polyester blouse increases the AMF values, when it is burnt with single layer and eight layer Fabric specimen along with cotton bra The AMF values increase from 0.51-0.57 cdcm’s at single Fabric specimen combination to 3.20-4.40 caUcm’s at B(PFSA7 combination, The AIHF values also increases from 5.085.31 caUcm’s at 8SA7 combmtion to 5.23-5.56 cdcm2s at B(P)t8SA7 combination. This rise in AMF values signifies that polyester blouse also significantlyincreases the AEIF values. It is found that in this case that as the number of cotton Fabric specimen layers increases, gsm increases which in turn increases the AMF value, depending upon the composition of the material, more the amount of hydrogen and carbon more will be the AIHF. From the above observations it is observed that i,n all the cases of cottovFabric specimen combinations the maximum AIHF occurred at 90 tests as comparedto 45 .
F
Polyester: Cotton (50:SO): Ignition studies & AIHF studies The analyses of ignition studies on Polyester: cotton 5050 Fabric specimen reveals that, the Fabric specimencan be easily ignited from its various combinationsat maximum 3.5 s and minimum 1.5 s, showing ease of ignition at single layer and difficulty at multiple layers. The ignition studies also reveals that time for ignition depends upon not only the material but also the number of layers to be ignited. Polyester: cotton 5050 Fabric specimen single layer easily ignites at 1.5 s, where as with eight layers it ignites at 2 s. Even the ignition time of cotton Fabric specimen changes when it is burnt with polyester blouse taking 2.8 s to ignite. The ignition time of polyester: cotton 5050 increases from 3.2 to 3.5 s, when it is bumed with light cotton petticoat fabric, but the ignition time remains unaltered for 2 and 3 layers combination.
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It was found h m Table 6.11 that, when polyester: cotton Fabric specimen is tpsted with different combinations ,the AIHF is 6.20 and 6.51 caVcm2s at 45' and 90 test respectively for the UV+PL+lOSA8 combination, where the total gsm is 978 . Where as for the B+B (P)+8SA8 combination with 641 gsm the AIHF is 6.21 and 7.20 cal/cm2s at 45' and 90' tests respectively. The minimum AIHF value is 1.32-2.03 caVcm2s at combination 1SA8. The number of hydrogen and carbon atoms available in 978 gsm is more than that at 641 gsm. More the mass more will be the propcrtion of strong bonds and more will be the energy required for formation and dissociation of these bonds libemting more heat during this burning exothermic reaction. It can be seen that polyester blouse increases the AEIF values, when it is burnt with single layer Fabric specimen and eight layer Fabric specimen along with cotton bra. The AIHF values increase from1.32-2.30 caVcm2s at single Fabric specimen combination to 3.80-4.23 cal/cm2s at B(P)+SA8 combination. The AIHF values also changes from 4.124.95 callcm's at 8SA7 Fabric specimen combination to 5.08-5.56 cdcm2s at B(P)+8SA8 combination. This rise in AMF values signifies that polyester blouse significantly increases the AIHF values. It is found that as the number of polyester: cotton Fabric specimen layers increases, gsm increases which in turn increases the AIHF value, depending upon the composition of the material, more the amount of hydrogen and carbon morc will be the AIHF. From the above observations it is seen that in all the cases of polyester: cotton Fabric specimen combinations the maximum ARF occurred at 90" test as compared to 45" as similar to other Fabric specimen cases.
Polyester: Viscose (50:50): Ignition studies Polyester: Cotton (50:50) The analyses of ignition studies on polyester: viscose 50: 50 Fabric specimen reveals that, the Fabric specimen can be easily ignited h m its various combinations. It takes maximum 3.6 s and minimum 1.7 s to ignite, showing ease of ignition at single layer and difficulty at multiple layers. The ignition studies also reveals that time for ignition depends upon not only the material but also the number of layers to be ignited. Po1yester:viscose 5050 Fabric specimen single layer easily ignites at 1.7 s where as with its 8 layers ignites rt 3.1 s. Even the ignition time of Fabric specimen changes when it is burnt with cotton blouse fabric 3.4 s and po1yester:cotton blend fabric 3.1 s as compared to polyester blouse taking 3.2 s to ignite. It was found &om Table 1.3 that, when po1yester:viscose Fabric specitpen is tested with different combinations the AIHF is 8.06 and 9.16 cal/cm2s at 45 and 90 test respectively for the UV+PL+lOSA9 combination, where the total gsm is 938. Where as for the B+F (P)+8SA9 combination with 761 gsm the AIHF is 7.19 and 7.60 cal/cmZsat 45' and 90 tests respectively.The minimum AIHF value is at combination 1SA9 is 1.20-1.69 caVcm2s. The number of hydrogen and carbon atoms available in 938 gsm is more than that at 761 gsm. It can be seen that polyester blouse increases the ATHF values, when it is burnt with single layer Fabric specimen and eight layer Fabric specimen along with cotton bra. The A I H F values increase froml.20-1.69 callcm's at single Fabric specimen combination to 1.72-2.15 cal/cm's at B(P)+SA9 combination. The AIHF values also changes from 4.124.95 caVcm2s at 8SA9 Fabric specimen combination to 5.23-5.80 cal/cm2s at B(P)+8SA9
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combination. This rise in AMF values signifies that polyester blouse significantly increases the AIHF values as seen even in other cases of Fabric specimen combination. It is found that as the number of po1yester:viscose Fabric specimen layers increases, gsm increases which in turn increases the AIHF value, depending upon the composition of the material, more the amount of hydrogen and carbon more will be the AMF.From the above observations it is observed that in all the cases of po1yester:viscose Fabric specimen combinations the maximum AMF occurs at 90"test as compared to 45" as seen in all cases of Fabric specimen.
CONCLUSIONS 1. Time for ignition for blended fabric depends upon the ignition temperature of the individual component of blend and proportion of that component in the blend, more the proportion of higher ignition temperature fibres, more will be fime required by the blend to reach the ignition temperature. 2. It is found that as the number of fabric layers increases, gsm increases which in turn increases the number of hydrogen and carbon atoms. The energy liberated due to breaking of the bond between the atoms is an exothermic reaction, which takes place during burning, there by increasing heat emission, incident heat flux and thus the AIHF value, depending upon the molecular structure, hydrogen and carbon content and type and length of bonding existing between the molecules. 3. For the cases of all Fabric specimen combinations, the maximum AIHF occurred at 90" test as compared to 45". 4. Average incident heat flux studies show dissimilar results and ranlung of fabric (saree) along with the supporting garments. As the burn-injuries are due to incident heat fluxes on the skin, increase in the average incident heat flux,increasesthe severity and higher will be the degree of burn. Accordingly, cotton w e e show least average incident heat flux and ranks first in safety followed by nylon, polyester: viscose (50:50), polyester: cotton (5050) and polyester.
REFERENCES 1 Fire Statistics, United Kingdom, 1997, The Home Office, The Government Statistical Office, UK, ISSN 0143 6384 UK, ISSN 0143 6384 (1998). 2 Mandate1263 to CEN. in The Field of Standardization Relative to the Safety Consumers
for a Feasibility Study on Possible Standardization on Fire Resistance of Nightwear, Directorate General XXIV, Brussels, 8 December 1997, Report to U E., 16 June (1999). 3 BS 5438:1989, British Standard Methods of Test for Flammability of Textile Fabrics when subjected to a Small Igniting Flame Applied to the Face or Bottom Edge of Vertically Oriented Specimens (1 989). 4 G S Nadiger, K S Murlidhara, Anand, P Modekar, P P Khan&, 2003 3(2) 3-2 1
J of Textile Committee,
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ASSESSING THE PERFORMANCE OF ALTERNATING PRESSURE AIR MATTRESSES (APAMs) S. V. S. Rithalia and G. H. Heath, School of Heath Care Professions, University of Salford, Salford, UK.
Pressure ulcers cause great pain and suffering to patients and their treatment is both costly and time consuming, therefore every effort should be directed towards their prevention and treatment. Patients with impaired blood circulation in the lower extremityare at particularly high risk and global demogr&ic trends might suggest that this factor will become increasingly problematic over time. The heel is most prone to tissue damage due to substantially higher interface pressurcs (IPS) plus the increased likelihood of peripheral vascular disease associated with a more aged population. There are many products on the market that attempt to provide pressure redistribution (PR) to this problematic area and alternating pressure air mattresses (APAMs)are widely used both in the institution and in homecare settings. However, some devices may be based on dated technology and may no longer be aligned to the rapidly evolving needs of the patient. Strategy depends on the ability of hyperaemia after PR to adequately compensate for intervals of flow deficits. We investigated the effect of pressure-relief on heel blood flow, in diabetic patients and healthy adult volunteers, using interface pressure and laser Doppler (LD) blood flow measurements, when the subjects were lying supine on four different APAMs. They included the DuoTM and the Duo 2TM (HillRom Inc), as well as the NimbusTM3, the Nimbus LogicTM (Huntleigh Healthcare Ltd). The measurements elicited significant differences in the performance of the A p A M s and indicated how new technology had influenced performance. An interesting finding was that low air cell pressures do not necessarily produce lower IPS, under the heel, contrary to the intuitive classical notion.
INTRODUCTION Pressure ulcer management demands the use of significant amounts of resource including equipment, wound care products as well as nursing time. While for the patient and their family, pressure ulceration can have a negative physical, social, financial, emotional and mental impact'' and is positively correlated with increased patient mortalig. Given the significant burden of this condition, every effort should be directed toward prevention and treatment with emphasis placed on establishing both the effectiveness and cost-effectiveness of the chosen therapeutic modality. It is also important to consider demographic and healthcare trends which, in most developed countries illustrate a shift toward an aging population. This is associated with an increase in the number of frail elderly individuals likely to suf5er a range of age-related chronic conditions. Patient morbidities are also rapidly changing; obesity for example has reached epidemic proportions4 along with the incidence of diabetes, thereby also increasing rates of peripheral vascular disease, is likely to more than double by 2030 to reach 366 million worldwide5. Technological advances mean that patients, of€en with multiple co-pathologies, survive complex surgical procedures but without aggressive preventative measures, have an increased risk of pressure ulcer development.
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In recent years there has been a considerableincrease in both the variety and number of patient support surfaces6s7.The cost of these devices ranging fiom a few hundred to several thousand pounds and hence the importance of a logical approach to their selection cannot be overstated. Alternating surfaces are amongst the most popular devices for the prevention and treatment of pressure ulcers8-”. They vary considerably in their design, cost, reliability, maintenance and ease of With the emphasis placed on evidence based health care, and cost effectiveness, it is essential that clinicians are provided with research evidence to assist them in equipment selection. However, health-care staff who are required to select a technologically sophisticated range of mattresses are faced with a confusing and often misleading array of commercial literature. Inappropriate selection not only wastes capital resources, but it can also be detrimental to the patient. In spite of recent trends in the UK towards basing clinical decisions on evidence from randomised controlled trials13, the selection of support surfaces remains a relatively neglected area, with little solid theoretical evidence and few properly controlled clinical Patients with impaired blood circulation in the lower extremities are at particularly high risk of developing pressure ulcers at the heel due to substantial1 higher tissue interface pressures and a relatively lower resting blood perfusion level? The literature consistently sites the heel as one of the most common anatomical locations for pressure ulcers to develop” and hi ights that heel pressure ulcers are increasing particularly in elderly bed fast patients’ -20. There are many products on the market that attempt to provide pressure relief (PR) to this problematic area and alternating pressure air mattresses (APAMs) are widely used both in the institution and homecare settings. These devices appear to offer the benefit of actively encouraging tissue perfusion by alternately increasing and decreasing the pressure exerted under the body by the supporting surface. However to achieve this, system must have a sufficient amplitude and time duration. Where systems have a very shallow lodoffload profile, then perfusion may be significantlyaffected, particularly in the heel area. Clearly not all alternating systems are the same and although many different type of APAMs are used for the prevention and treatment of pressure ulcers, only a few high quality randomised controlled trials (RCTs) are available on which to base purchasing decisions. Given the implications, for morbidity and delayed rehabilitation, some alternating pressure-redistributing mattresses incorporate technologically advanced heel ‘zones’. How these designs affect clinical outcome are largely unknown, particularly in patients with peripheral vascular disease. The effectiveness of mattresses is best evaluated through clinical trials, but they are expensive to conduct and in the case of new products, such evidence is not readily available. Faced with this situation, physiological measurements are increasingly being used as a surrogate. Laboratory evaluation techniques have centred largely on body-surface contact or interface pressure (IP) measurement, typically analysing discrete maximum and minimum levels or average pressure. However, tissue damage, including pressure ulceration, is explicitly linked to both the time and the pressure. At the University of Salford in collaboration with Salford Royal Hospitals a computerised pressure-time based system (Fig 1) has been developed2’,which measures IF’, air cell pressure (AP) and skin tissue perhion using laser Doppler (LD) flowmet#. The system calculates pressure-time characteristics known as pressure relief index (PRI) and perfhion time-integral data. Previously reported results using this method have demonstrated that the techni ue can illustrate the, often marked, differences between apparently similar devicesz1 . Mattresses evaluated in the studies included, the Duom (Hiill-Rom Inc) and Nimbusm 3 (Huntleigh Healthcare Ltd), both
P
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of which have been developed, upgraded and renamed as the Duo 2TM and Nimbus Logicm respectively. Both upgrades are more expensive than the earlier versions, which according to the manufacturersreflect the improvementsin their performance.
Fig. 1. PRI monitoring equipment used for measurements on Duo 2TMmattress: (a) computer, (b) interface pressure monitor, (c) box containing air pressure transducers, (d) laser Doppler monitor, (e) mouse, (0 key board, (g) printer and (h) computer screen.
METHODS AND MATERIALS The technical performance of two systems (Duo", Hill-Rom Inc and NimbusTM3, Huntleigh Healthcare Ltd) was tested in 16 diabetics using PRI and tissue perfhion technique. The test was repeated using 14 healthy volunteers and later versions (Duo 2m, Hill-Rom Inc and Nimbus LogicTM, Huntleigh Healthcare Ltd) of each following the addition of specialised heel zones. For each mattress the following measurements and data were acquired on the heel: 0 mean maximum and minimum interface pressures 0 mean peak air pressures in the mattresses 0 interface pressure durations below 30,20 and 10 mm Hg over a 60 minutes period mean maximum LD blood perfusion mean area under the LD blood perfusion curves
Subjects Sixteen diabetic atients (7 males, 9 females) participated in the first study (DuoTM versus NimbusJ3). Their ages, weights, heights and body mass index (BMI) ranged from 26 to 79 (mean k SD, 61.1 f 15.7) years, 56 to 95 (77.3 f 13.2) kg, 1.60 to 1.82 (1.66 f 0.10) m and 22.8 to 37.8 (28.3 f 5.1) respectively. They were recruited from the outpatient diabetic clinic of the Withington Hospital. The second study (Duom versus Nimbus Logic? included 14 healthy adult volunteers (8 males, 6 females) recruited h m postgraduate students and staff of the University of Salford. Their ages, weights, 0 Woodhead Publishing Limited, 201 0 501
heights and BMI ranged fiom 18 to 58 (mean f SD, 33.8 f 10.7) years, 53 to 121 kg (73.0 f 19.7), 1.59 to 1.91(1.69 f. 0.07) m and 21.4 to 30.9 (25.3 f 2.4) respectively. All subjects had the procedure fully explained to them and their written consent was obtained prior to the commencement of the measurements.
Equipment Interface pressure measurements were made with the Oxford Pressure Monitor, Mark 11, (Talley Group Ltd, Hants, LJK) employing techniques developed by our research group over the past twenty years. Measurement of skin blood flow with laser Doppler probe (Softflo, model BPM2, Vasamedics Inc, MN, USA)) were also carried out on each subject. The air pressures inside mattress cells were recorded simultaneously. The pressure time characteristics were analysed by a computerised system (Fig. l), which records AP, IP and pressure-time characteristics of APAMs. The system calculated the time that the interface pressute remained below three arbitrary thresholds, in this case 30,20 and 10 mm Hg. These values were chosen to indicate IP close to and below the microvasculature operating pressuresM. The software expressed interface pressure as a percentage of the mattress cycle, termed the pressure relief index (PRI). This allows like-for-like comparisons to be made between APAMs operating with different cycle fiequencies and sequences. Simultanmusly LD measurements were recorded using the same computer software. The area on the pressure time graph between the horizontal line and the corresponding LD blood flow was calculated. This area was referred to as the ‘perfusion/cycle’ in arbitrary units (AU). Procedure
The pump connected to the mattress was first switched on and allowed to operate for at least 45 minutes prior to any testing. The same room, at a regulated temperature between 23’ and 26’C, was used for each study to carry out all measurements. The first study was carried out at the Withington Hospital and the second at the Hope Hospital. A standard hospital cotton sheet was draped over each APAM prior to testing. The subjects were asked to lie on the matlress wearing normal light clothing,, with legs uncrossed and arms at sides, Two standard pillows were used to support the head. Care was used to place both the left and the right heels on the centre of the same air cell of a mattress. The inkdace pressure (IP) transducer was placed under the right heel and the laser Doppler on the left heel with the feet in a neutral position in order to maintain uniformity of the method through out the measurements. Measurements of IP and LD as well as AP were taken simultanmusly over at least two alternating cycles.
RESULTS A brief description of each APAM with its principles of operation is presented. Initially the results obtained were in the form of pressure/ time graphs output. A typical recording of the time-varying characteristics and physiological response is illustrated in Fig. 2. The pressure relieving (PR) characteristics of the mattresses are presented in terms of interfhce pressure (IP) and LD blood flow values. Data are given throughout as mean f standard deviation (SD). Statistical analysis was performed by means of appropriate statistical tests using the Analyse-It (Analyse-It Software Ltd, Leeds, LJK) computer programme. Differences between various pressure and LD values were analysed using the Student’s t-test or the Mann-Whitaey U test, depending as to 502 0 Woodhead Publishing Limited, 2010
whether or not the data were normally distributed. A difference was considered significant when pX0.05.
Fig. 2. A typical recording on the heel of the time-varying characteristics and physiological response.
DuoTM The DuoTMsystem consists of two very complex and independent elements: a mattress with 19 air cell enclosed in a cover and a De.teqm pressure control module. The mattress incorporates a low pressure heel zone (Real HeelTM)at the foot end, which operates in both continuous and alternating therapy modes. The De.teqTMpressure control module ensures that all the air cells are automatically regulated at the lowest possible support pressure. For the 16 diabetic patients, the overall maximum interface pressure values during the inflation phase of the cycle under the heel were 126.8 28.4 mm Hg and during deflation phase the minimum values were 57.B 13.5 mm Hg. The mean maximum air cell pressure values for the heel were 7.8 f 0.9 mm Hg. Interface pressures at the heel remained above 30 mm Hg during the whole cycle for all subjects. Skin LD blood flow integrated over time for one cycle was 1356.1 f 878.0AU.
*
NimbusTM3 This replacement mattress consists of 20 individual modular air cells having a figure-ofeight construction,placed transversely and connected alternately in two groups. Each of the two gro s is inflated and deflated with a cycle time of 10 minutes. A sensor pad (Auto-matt ), which lies under the air cells, forms an integral part of pressure relief system. The Auto-matt* can detect and automatically change the inflation pressure according to posture and subject weight. This aims to lower the peak interface pressure on soft tissue and generate greater levels of comfort. One of the innovative developments is the inclusion of five Heelgumdm cells at the foot of the mattress.
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5000
--
4000
-
Mcm perfbion per cycle
3000 $2000
E
Fig. 3. Bar chart showing mean perfusion per cycle on the heel in diabetics when the patients were lying supine on the DuoTMand Nimbusm 3 mattresses. For the 16 diabetics, the overall maximum interface pressure values during the inflation phase of the cycle under the heel were 134.4 f 31.7 mm Hg and during the deflation phase the minimum values were 19.1* 8.1 mm Hg.The mean maximum air cell pressure values were 29.8 f 1.2 mm Hg. The time intervals calculated over 60 minutes when IP remained below arbitrarily chosen thresholds of 30 and 20 mm Hg were 19.3 f 8.8 (range 0 - 33) and 8.4 f 8.8 (range 0 - 23) minutes respectively. There was no significant difference in peak IPS under the heel between the Duom and the Nimbusm 3 despite the DuoTMoperating at significantly lower (P
The Duo 2 m like the DuoTMsystem consists of two complex and independent elements: a mattress with 21-air cells (Heel = 8, Sacrum =12 and Head = 1) enclosed in a cover and a De.teqTMpressurecontrol module. Inflatioddeflation cycle time of the heel cells is 5 minutes and torso cells inflate and deflate at a cycle time of 10 minutes. The mattress incorporates a low-pressure heel zone (Real Heelm) at the foot end. The De.teqTMpressure control module ensures that all the air cells are automatidly regulated at the lowest possible support pressure. All hnctions, including CPR mode, are controlled by a compact, lightweight and easy to use control pendant. For the 14 subjects, the overall maximum interface pressure values during inflation phase of the cycle under the heel were 130.1 f 22.2 mm Hg and during deflation phase the minimum values were 47.5 f 10.6.1 mm Hg. The mean maximum air cell pressure values were 13.6 f 1.2 mm Hg. Interface pressures at the heel remained above 30 mm Hg during the whole cycle for all subjects.
Nimbus LogicTM The Nimbus Logic consists of 21 individual polyurethane air cells, which inflate and deflate, with a cycle time of 10 minutes. The four head cells are raised to enhance patient comfort. They are also narrow to avoid mattress induced head movement when alternating. The five cells at the foot end of the mattress run at a lower pressure and 504 0 Woodhead Publishing Limited, 2010
encompass the Heelguard@technology, which ensures that the patient’s heels are provided with the maximum pressure relief. The mattress system also incorporates an advanced sensor pad called the Auto-Matt, which, together with the Mattress Control Module (MCM) ensures that the patient is automatically supported at optimum pressures at both the trunk and heels regardless of size, height, position or weight distribution. Mean perburion per cyrk 7000
6000
Fig. 4.Bar chart showing mean perfkion per cycle on the heel in healthy adult volunteers when they were lying supine on the Duo 2m and Nimbus Logicm mattresses. For the 14 subjects, the overall maximum interface pressure values during the intlation phase of the cycle under the heel were 142.3 f 22.5 mm Hg and during the deflation phase the minimum values were 9.2 f 3.8 m m Hg. The mean h u m air cell pressure values were 22.7 k 2.3 mm Hg. The time intervals calculated over 60 minutes when IF remained below arbitrarily chosen thresholds of 30,20 and 10 m m Hg were 23.7 f 4.4 (range 16 - 31),16.9 & 6.4 (range 7 - 28) and 4.6 f 4.3 (range 0 - 15) minutes respectively. Skin LD levels (Figure 4) integrated over time were significantly greater (P
DISCUSSION The interface pressure and tissue perfision studies elicited significant differences in the technical performance of both product types (the current version of each and its predecessor). The amplitude of the off-loading cycle plus the duration of off-loading correlated directly to tissue perfusion in the heel: whether from a healthy or a diabetic subject with higher amplitude equating to higher perfusion. In both groups an inverse relationship was found between maximum as well as minimum IP and heel skin LD measurements, but it was not statistically significant. However, there was a good positive relationship (~0.7) between PRI and blood perfusion values. There was no statistical difference in LP values between the two groups. The blood flow values were significantly different in diabetic and non-diabetic subjects. Average skin blood perfhion measured over one cycle for the healthy subjects was significantly higher @<0.01) compared with the patients Except in a few cases with the Nimbus LogicTM mattress complete heel off-loading was not achieved during the deflation phase of the cycle. When the heel was completely off-loaded by liKig it from the support surface, 0 Woodhead Publishing Limited, 2010 505
maximum peak perfhion was greater than that achieved during the pressure-relief period on the mattresses. Analysis of the perfusion curves h m the two studies resulted in showing faster rates of rise time to m i m u m value and slower decay in non-diabetic subjects compared with diabetic patients. It seems diabetes interferes with the cutaneous response to ischemia25. Both systems appear to have improved their performance in giving better pressure relief on the heel. Compared with the Duo, the Duo 2m system demonstrated some improvement in IPS (Duom = 57.2 f 13.5 mm Hg versus Duo 2 = 45.5 f 10.6.1 mm Hg) during the deflation phase of the cycle. The Nimbus LogicTM demonstrated significant improvement below 30, 20 and 10 mm Hg thresholds on the heel. While there were differences in the interface pressure-relieving performance of the old and new products and between the two new products, the relationship between interface pressure measurement and clinical outcomes is still unclear. Ultimately, the effectiveness of these devices can only be fully demonstrated by controlled clinical trials. Meanwhile, based on current results, it appears that the NimbusTMsystem has a theoretical advantage over the Duom system in protecting skin tissue at the heels from the deleterious effects of prolonged recumbency, with the former device showing good performance in high risk patients in a multi-centre clinical outcome studg6Also . based on the present combined results of IP and blood -ion in diabetic patients and healthy subjects, it appears that, to produce hyperaemic reaction in the skin tissue or rep e f i i o n after loading an appropriate course of action is to provide periodic complete and a or near complete off-loading. A previously published laboratory in~estigation~~ clinical stud?’ support this finding. The present combined results of IP and blood flow appear to suggest that the measurement of maximum and minimum interface pressures alone by themselves are inadequate parameters to assess the impact of pressure loading on heel tissue. Our results also indicate that there are functional microvascular disturbances in the heels of diabetic patients. When loaded for a similar duration and pressure, blood flow hyperaemic response is weaker in these patients compared with non-diabetic subjects. Despite appearing similar, the technical performance of an APAM can have a marked effect on perfusion. If the cycle is shallow or short, perfusion may not occur. In the absence of an agreed minimum specification for an APAM clinicians should be aware that the APAM they select may not be optimised in the heel area; laboratory data such as this can aid decision making. It is also important to note that low air cell pressures do not necessarily produce lower IPS under the heel, contrary to the intuitive classical notion.
ACKNOWLEDGEMENTS This study was partly supported by an unrestricted and unconditional grant from HuntIeigh Technology plc of Luton (UK).
1 K Spilsbury,A Nelson, N Cullum, C Iglesias, J Nixon, S Mason, ‘Pressureulcers and their treatment and effects on quality of life: hospital inpatient perspectives’, JAdv NWS, 2007 57 494-504. 2 A Hopkins, C Dealey, S Bale, T Defloor, F Worboys, ‘Patient stories of living with a pressure ulcer’, JAdv Nurs, 2006 56 345-353. 506 0 Woodhead Publishing Limited, 2010
3 F h d i , G Onder, A Russo, R Bernabei, ‘Pressure ulcer and mortality in hail elderly people living in the community’, Arch Gerontol Geriafr, 2007 1 (Suppl) 217-223. 4 WHO Global strategy on diet, physical activity and health. At: http://~.who.int/~etphysicalactivity/publicatio~facts/obesi~/e~ Last accessed 21.3.2007. 5 WHO Diabetes programme. At: http://www.who.int/diabetes/en/. Last accessed 21.3.2007. 6 G Thompson, ‘Softform active mattress: a novel step-up/step-down approach’, Br J NWS. 2006 15 988-993. 7 D Mackey, ‘Support surfaces: beds, mattresses, overlays-oh my!’, Nurs Clin North Am, 2005 40 251-265. 8 C Iglesias, J Nixon, G Cranny, E A Nelson, K Hawkins, A Phillips, D Torgerson, S Mason, N Cullum, ‘Pressure relieving support surfaces (PRESSURE) trial: cost effectiveness analysis’, BMJ2006 332 1416 - 118. 9 Willis J. Flotation beds: latest developments. Nurs Times 1996; 92: 46-48.
10 M Bliss, Geriatric medicine. In: Bader DL (ed), Pressure Sores: Clinical practice and scientific approach. London: Macmillan, 1990: pp65-80. 11 S V S Rithalia, G H Heath, ‘A change for the better? Measuring improvements in upgraded alternating-pressureair mattresses’ J Wound Care, 2000 9 437-440. 12 N Lockyer-Stevens, ‘A developing information base for purchasing decisions: a review of pressure-relievingbeds for at-risk patients’, ProfNurs 1994 9 534-542. 13 D L Sackett, W M Rosenberg, J A Gray, R B Haynes, W S Richardson, ‘Evidence based medicine: what it is and what it isn’t’, B W 1996 312 71-72. 14 D R Thomas, ‘Issues and dilemmas in the prevention and treatment of pressure ulcers: a review’, JGerontol MedSci, 2001 56A: M328-340. 15 N Cullum, J Deeks, T A Sheldon, F Song, A W Fletcher, ‘Beds, mattresses and cushions for pressure sore prevention and treatment’, Cochrane Database Sysf Rev, 2000 2: CD001735. 16 H N Mayrowitz, J Macdonald, J R Smith, ‘Blood perfusion hyperaemia in response to graded loading of human heels assessed by laser Doppler imaging’, Clin Physiologv, 1999 19 351-359. 17 K Whittington, R Briones, ‘National Prevalence and Incidence Study: 6-year sequential acute care data’,A& Skin Wound Care, 2004 17 490-494. 18 J Donnelly, ‘Hospital acquired heel ulcers: a common but neglected problem’, J WoundCare, 2001 10 131-135. 0 Woodhead Publishing Limited, 2010 507
19 L Schoonhoven, T Defloor, M H F Grypdonck, ‘Incidence of pressure ulcers due to surgery’, JClin Nurs, 2002 11 479-487. 20 M Ohwa, H Sauada, J Sugama, M Inagaki, C Konya, A Kitagawa, K Tabata, ‘A prospective cohort study of lower-extremity pressure ulcer risk among bedfast older adults’, A h Skin Wound Care, 2006 19 391-397. 21 S V S Rithalia, ‘Evaiuation of alternating pressure mattmses: one laboratory-based strategy’, J Tissue Viability, 2004 14 51-58.
22 H N Mayrovitz, J Smith, ‘Heel-skin microvascular blood perfusion responses to sustained pressure loading and unloading’, Microcirculation, 1998 5 227-233. 23 S V S Rithalia, L Russell, ‘Evaluation of alternating pressure air mattresses using a time based pressure threshold technique and laser Doppler micro-vascular perfusion measurements on the heel’, EPUAP Review, 2003 5 15-16. 24 A C Guyton, Textbook of Medical Physiology, 8th ed. Philadelphia: W.B. Saunders CO;1991 ~ ~ 1 7 0 - 1 8 3 . 25 S V S Rithalia, C Van Shie, M Twiste, M Gonsalkorale, ‘Effect of alternating pressure on skin blood flor’. In D Boone (editor). Proceedings of the 11” Congress of International Society for Prosthetics and Orthotics. ISBN 988-9797-1 -0. Hong Kong 2004 pp231. 26 M Clark M, ‘Changing pressure redistributing mattress stocks: costs and outcomes’. Br JNurs, 2005 14 (Suppl) 30-32. 27 L Russell, T M Reynolds, ’Raudomised controlled trial of two pressure-relieving systems’, J Wound Care, 2000 9 52-55.
508 0 Woodhead Publishing Limited, 2010
SMART TEXTILESWITH SLOW-RELEASE CERAMIDES FOR SENSITIVE SKIN
M.Marti,', M. Lis?, J. A. Navmo? R Ramirez,', L. Coderch,', J. Valldeperas? and J. L. Parra'
'II AB CSIC), Jordi Girona 18-26,08034Barcelona, Spain 'NIkXTEIt
(UPC), Colom l5,08222Terrassa, Spain
ABSTRACT Ceramides are the main constituents of the lipid lamellas present in the intercellular domains of the stratum corneum from human skin. They have a main role in the structure and the barrier function of the skin, which is fundamental in the sensitive skin. Recent studies have demonstrated that the liposome structures formed with internal wool lipids with a relevant amount of ceramides provide both a reinforcement of the barrier function of the skin and an increase of the cutaneous hydration (1,2). The present project has been designed to obtain new smart textiles containing ceramides to c oder a regenerative effect to the skin in contact with them based on their repairing properties of the barrier function. The experimental methodology used to achieve an appropriate application of the vehicles into textiles (polyamide or cotton) to obtain a gradual release of the active compounds (ceramides) is being investigated. The main aim is to provide a beneficial and repairing skin effect taking into account the existing friction between skin and textile. On the other hand, ethylhexyl methoxycinnamate have been encapsulated in different vehicles and used as reference probes to follow their fmation and release into the textiles.
INTRODUCTION Sensitive skin is a cutaneous condition of subjective hyperreactivity to xenobiotic factors (3). Approximately 40% of population consider themselves to possess the characteristics of sensitive skin (4). The lack of knowledge in understanding mechanisms involved make this concept difficult to define. However, recent investigations seem to confirm, as a probable etiology, the increase on the permeability of the stratum comeum possibly due to an unbalance of the stratum corneum lipids. This circumstance will give rise to an increase of the cutaneous penetration of exogenous factors and to an acceleration of the nerve response in the cutaneous receptors present in the epidermis which could cause harmful effects on sensitive skin (5). The current skin hygiene habits facilitate these circumstances and thus, the existence of many cases of sensitive skin. Some textile materials which have direct contact with the skin could induce, depending on its chemical composition, an irritation condition characteristic of sensitive skins. This fact, which could be a problem, has allowed the forthcoming of an innovative development in the textile sector. The smart textiles besides promoting the classical function of covering the skin, could be the appropriate substrates to progressively and continuously deliver some specific compounds, previously applied on the textile, to protect and reinforce the barrier function of the skin. Therefore, the sensitive skin cases detected by the dermatologists or declared by the consumer may be decreased. 0 Woodhead Publishing Limited, 2010 509
Ceramides are a structurally heterogeneous complex group of sphingolipids which contains derivatives with phytosphingosine or sphingosine as a base bound to different fatty acids by an amide linkage. Ceramides are the main constituents of the lipid lamellae present in the intercellular spaces of the stratum comeum from human skin. They have a main role in the structure and they maintain the skin barrier function. They also prevent the penetration of external agents and control the transepidermal water loss maintaining the physiological water content in the skin. A new project has been designed by our group which deals with the preparation of smart textiles containing ceramides which could give the skin a regenerative effect while being in contact with them with the aim of repairing and reinforcing the skin barrier function. Nowadays, there are Werent kinds of smart textiles in the market able to release several active compounds. However, based on the bibliography and as far as we know, there are not scientific studies to describe an appropriate experimental methodology so as to achieve the initial fixation of the active compound and its subsequent gradual release onto the skin. Furthermore, the scientific demonstration of its efficacy is unclear. For these reasons, this project is based on the development of an integral methodology taking into account different steps ranging from the preparation of the vehiculized active compound up to the scientific demonstration of the cutaneous efficacy of the smart textile. Smart textiles are materials which react to the external or internal stimuli. In the present project the main objective is to fix ceramides in the textile, through different vehiculizing strategies, promoting to a gradual liberation of these compounds due to the friction with the skin, aiming at providing a beneficial and repairing skin function to avoid cases of sensitive skin. In this paper, two preliminary stages of the project are presented. Firstly, the characterization of ceramides from wool fibres has been made, their capability of forming liposomes has also been explored, and their benefits when they are topically applied have been assessed. Secondly, the methodology to follow their future application on textiles has been initiated by the use of a reference compound, the ethylhexyl methoxycinnamate (OMC) due to suitable analytical determinationby HPLC (6) or by spectrophotometer W-VIS techniques. The microcapsules with OMC have been prepared by the industry Lipotec and their application on cotton has been made by foulard.
CERAMIDES FROM WOOL At present, the market uses ceramides prepared by synthetic or biokchnological methodologies. The price in both cases is very high (approx. €1.800/Kg) and furthermore they do not posses the same chemical composition as the ones present in the nature (skin, hair, natural proteic fibres). Wool is a natural fibre with a main proteic composition and with an external lipidic content widely used in cosmetics named lanoline and an internal lipidic content in a small proportion (1.5%) which can be of a great added value because of its high content of ceramides. Many studies have been performed in our laboratories based on the extraction, analysis and structuring the internal lipids fiom wool and specially the ceramides (7-9).The analytical and physicochemical studies indicate a relevant resemblance between the internal wool lipids (IWL) and the lipids h m the stratum comeum of the human skin (10, 11). Therefore, the strategy to obtain these natural extracts rich in ceramides and its interest for the pharmaceutical and cosmetic industry led us to file the correspondingpatent (2). 51 0 0 Woodhead Publishing Limited, 201 0
Ceramides can be obtained by extraction with organic solvents or by extraction with C& in supercritical state (12,13). Table 1. Comwsition of extracted liDids analyzed by Free Fatty Acids Cholesterol Cerarnides Glycosilceramides Sterolsulphate
0.109 0.048
0.159 0.037 0.053
In this project, lipids h m raw Spanish Merino wool extracted at a pilot plant level were used. Merino wool from Spain was used because its internal lipid composition is similar to that found in the stratum comeum from skin (12, 14). In Table 1 the composition of lipid extracted with methanol is presented. The lipid analysis was made by TLC-FLD following the methodology detailed in previous papem (2, 8, 14). It can be seen that the ceramides are the main compound in the analyzed extract. LIPOSOME FORMATION AND EVALUATION Recent studies have demonstrated that the liposome structures formed with the lipids extracted from wool provide a reinforcement of the barrier function of the skin and an increase of the cutaneous hydration, as well as a repair effect of these properties in chemical or mechanical damaged skin (1, 15). Liposomes were formed with the IWL. Lipid extracts dissolved in chloroform/methanol 2:l (v/v) were evaporated to dryness, and hydrated with 0.9% NaCl solution to give a final lipid concentration of lOmg/mL. Multilamellar vesicle liposomes were formed by sonication of the suspension at 65OC for about 15 min (1, 15). The vesicle size distribution and polydispersity index of liposomes were determined by a dynamic light scattering technique using a photon correlator spectrometer(Malvem Autosizer 4700c PS/MV). Samples were diluted from 10 to O.lmg/mL. Quartz cuvettes were filled with the samples, and all the experiments were thermostatically controlled (25°C). The samples were measured at a scattering angle of 90". Thus, the data obtained were analysed using the version of the program CONTIN provided by Malvern instruments, England. This vesicular structure offers a suitable strategy to achieve an accurate vehiculization of a particular compound and to incorporate additional lipid content that may reinforce the barrier function of the skin (16- 18). The diameter and polidispersity index of the different liposome samples were analyzed by Dynamic Light Scattering for 22 days. The results obtained are indicated in Table 2. It can be appreciated that liposomes prepared from lipids extracted by methanol are stable during all the study, and the vesicular size increases a little (27Onm of diameter in the first day and 393nm at 22ndday).
APPLICATION OF IWLCERAMIDE LIPOSOMES It is well-known that the skin barrier and the water-holding capacity are the most important functions of the stratum corneum (SC). The s k i barrier prevents the 0 Woodhead Publishing Limited, 2010 51 1
imperceptible loss of vapour through the skin surf‘ace and it also protects the body fiom continuous environmental insults, whereas the water-holding capacity affects the skin Table 2. Stability of liposomes: vesicular diameter (0)and polidispersityindex @.I). Extract Methanol
1d8y 0(nm) P.L 270 0.456
8 day8 0(m) PJ. 358 0.335
15 days
0(m)
PJ.
344
0.296
22 day8 0(m) PJ. 393
0.479
visco-elastic properties. Furthermore, these fknctions are related to the composition and structure of SC intercellular lipids. The effect of topically applied IWL structured as liposomes on skin properties was evaluated by non-invasive biophysical techniques. Transepidermal water loss (TEWL) is a sensitive parameter to evaluate the skin barrier integrity. This parameter was measured using the Tewameter TM210 (Courage & Khazaka, Cologne, Germany). Moreover, skin hydration was determined by the Comeometer CM820 (Courage k Khazaka), which measures skin capacitance in arbitrary units (AU). Both parameters were obtained and recorded in accordancewith established guidelines (19,20). A medium-term study was performed to test the effect of the IWL liposomes when applied to undisturbed skin. Baseline measurements of TEWL and skin capacitance were taken on three marked areas (4 cm’) of the volar forearm before applying the corresponding solution: two zones for topical treatment (NaC1 solution as placebo and IWL liposomes) and one untreated zone (control). After basal measurements, 10 pI of placebo and IWL liposome solutions with a concentration of 10 mg/mL were topically applied. After 24 h (day l), both parameters were evaluated and then 10 pl of solution were applied again. This procedure was repeated once daily for 3 more days (days 2 , 3 and 4). Finally, TEWL and skin capacitance were measured three days after the last application (day 7). The parameters were normalised, dividing each value by the basal value. They are expressed in the figures as a percentage variation with respect to the control values. The eventual modification of the skin properties on undisturbed skin after the daily application of IWL structured as liposomes was investigated. It was observed that the IWL liposomes improved the skin barrier integrity (fig. 1) and increased the skin hydration (fig. 2) in contrast to the placebo solution which led to an increase in TEWL values and to a dehydration effect on the first days of the experiment. Moreover, it should be noted that the IWL liposomes were able to maintain these improvements for 3 days after the last application. The IWL liposomes have a beneficial effect on intact skin, reinforcing its barrier integrity and improving its water-holding capacity.
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i
7s 1
2
3
4
7
Time (days)
Fig. 1. Variation of TEWL values during the treatment period. Changes were doubly evaluated versus basal and control values.
4
95 1
2
3
4
7
T h e (days)
Fig. 2.Variation of skin capacitancevalues during the treatment period. Changes were doubly evaluated versus basal and control values. MICROENCAPSULATION Microcapsules with cationic character, prepared by the company Lipotec, have been used for application on cotton fabrics (Style 400, Test Fabrics, Inc). In a preliminary study, a sun filter (OMC) was used as a reference probe during the encapsulation process. The use of this probe permits quantitative evaluation of the amount of microcapsules incorporated onto the fabric. This item is basic when we are trying to obtain specific properties from a treated textile and in order to optimize the doses of active principle delivered. It is necessary to choose a simple method to establish a proper and useful system to determine the quantity of active principle present in the fabric because of the need to modify or re-operate batches in order to apply similar amounts of microcapsulesinto the textile. For its simplicity and good accuracy, a spectrophotometric technique has been chosen using a Shimadzu UV-2401model. 0 Woodhead Publishing Limited, 2010 513
To avoid eventual false signals provided by the ingredients of the microcapsule the active principle has been discharged h m the capsule using solvents. After several preliminary tests, deionised water and isopropilic alcohoVwater (50/50) showed the best extraction behaviour. In order to establish the calibration curve of OMC it’s necessary to choose the wavelength for which the evolution of absorbance versus concentration has the best adjustment and follows Lambert-Beer Law. In the case of deionised water the maximum absorbance is detected at 268 nm and with isopropanoVwater at 310 nm. Therefore, these wavelengths have been used to build up the corresponding calibration curves. With deionised water, the concentrations used were 1, 2, 5, 10, 20 and 40g/l. However, at higher concentrations than lOg/l, a microcapsule suspension was detected. The calibration curve was: Abs=O.O231*conc (R2=0.9998). With waterhsopropyl (50/50), the concentrations used were 0.05, 0.1, 0.25 and 0.5 gll, and the calibration curve was: Abs=2.89l*conc (R2=0.999). Table 3. Results obtained h m the microcapsules application on cotton tissues: tissue weight increase and OMC concentration in water after Soxhlet extraction.
2 3 4
16.61 16.29 15.33
0.0842 0.0801 0.0788
In order to simulate as much as possible the experimental conditions of an industrial process, a Pad-Seatm-Rame pilot plant was used (ERNST BENZ AG IUD-HT and KTF/m250). From a feeding cuvette filled with a 20% solution of microcapsules, the fabric was foularded at 5OOC. Then, the impregnated fabric was put into a curing and heat-setting chamber and maintained at 50°C for 15 minutes. Finally, the textile samples were conditioned to environmentalconditions and weighted. After the treatment, two textile samples of 1 gram were submitted to extraction by a Soxhlet. One by using deionised water and the other one by using Isopropanollwater (50/50) for 1 h. Results obtained after Soxhlet extraction with isopropanollwater (50/50) were not coherent with the amounts of microcapsules d e w e d during the pad-impregnation process. Four textile samples used for the experiment with water extraction were checked, the results obtained are shown in Table 3. The medium value of textile weight increased, after microencapsulation application was 15.25% (with a standard deviation of 1.613), and the concentration media of sun filter in water was 0.0802gL (standard deviation 0.0027). These values were in the range of the OMC microencapsulatedapplied.
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CONCLUSIONS The internal lipids from Spanish Merino Wool were extracted at pilot plant level with methanol as an extracted solvent and the ceramides were the main compound in the analyzed extract (0.16% oww). The liposomes prepared with these IWL rich in ceramides were stable for 22 days. The efficacy of these liposomes has been demonstrated on intact skin, reinforcing its barrier integrity and improving its water -holding capacity. The IWL rich in ceramides are considered promising candidates to be used as active compounds in the next step of the project, in order to obtain the smart textiles with beneficial properties for sensitive skins. An experimental procedure has been established to apply microcapsules of a sun filter into cotton fabric. Moreover, a quantifying methodology to determine the amount of OMC present in the textile processed has been developed using deionised water as extractor solvent. From the experimental results obtained it seems clear that more work has to be done in the field of microcapsules application to optimize the process. In our opinion, more robust arguments are needed at an experimental level in order to quantify the benefits of smart textile with specific active principles incorporated.
ACKNOWLEDGEMENTS The authors are indebted to Ms. I. Yuste for technical support. Thanks are also due to LIPOTEC for supplying microcapsules and to Dr. J. Cebrian from Lipotec for his technical advice.
REFERENCES 1 M de Pera, L Coderch, J Fonollosa, A de la Maza, and J L Parra, ‘Effect of internal wool lipid liposomes on skin repair’, Skin Pharmacol. Appl. Skin Physiol., 2000 13 188195.
2 L Coderch, J Fonollosa, M de Pera, A de la Maza, J L Parra,M Marti, Compositions of internal wool lipid extract of wool and use thereof in the preparation of products for skin care and treatment, US Patent Office Pat No PCT/ESOO/OO2279. 3 G Primavera, E Berardesca, ‘Sensitive skin: mechanisms and diagnosis’ Int. J. Cosm. Sci.. 2005 27 1-10. 4 E M Jackson, ‘The science of cosmetics’,Am. J. Contact Dermatol. 1993 4 108-110.
5 T Yokota, M Matsumoto, T Sakamaki, ct al. ‘Clasification of sensitive skin and development of a treatment system approriate for each group’, IFSCC Mug. 6: 303-307, 2003.
6 E Ramon, C Alonso, L Coderch, A de la Maza, 0 Lopez, J L Parra, J Notario, ‘Liposomes as alternative vehicles for sun filter formulations’, Drug Deliv. 2005 12(2) 83-88.
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7 L Coderch, C Soriano, A De la Maza, P Erra, and J L Parra, ‘Chromatographic characterization of internal polar lipids from wool’, J. Am. Oil Chem. SOC.1995 72 715720. 8 J Fonollosa, M Marti, A de la Maza, J L Parra, and L Coderch, ‘TLC-FID analisis of the ceramide content of internal wool lipids’, J Planar Chromatogr.2000 13 119-122.
9 L Coderch, A De la Maza, A Pinazo, and J L Parra, ‘Physicochemical characteristics of liposomes formed with internal wool lipids’, J. Am. Oil Chem. SOC.1996 73 17131718. 10 J Fonollosa, M Marti, A de la Maza, M SabBs, J L Pma, L Codetch, ‘Thermotropic behaviour of internal wool lipids’, Znf. Wool Text. Org., Dresden Meeting, Report n”4, 1998.
1 1 J Fonollosa, M Marti, A de la Maza, M SaMs, J L Parra, L Coderch, ‘Thermodynamic and structural aspects of internal wool lipids’, Langmuir, 2000 16 4808-4812. 12 L Coderch, J Fonollosa, M Marti F Garde A de la Maza,and J L Parra, ‘Extraction and analysis of ceramides from internal wool lipids’, J. Am. Oil Chem. SOC.2002 79 1215-1220. 13 L Coderch, R Ramirez, M Marti,A de la Maza, I Garay, J L Parra, Procedimiento para la extracci6n de 10s lfpidos intemos de la lana con fluidos supercrlticos, Spanish Patent Office, Pat No 200700543, March 2007. 14 L Coderch, J Fonollosa, M Marti, F Garde, and J L Parra, ‘Extraction and analysis of internal wool lipids in particular ceramide compounds’, Proc lo‘hZnf. Wool Tex. Res. ConJ, Aachen, Report ST-1 1,2000. 15 L Coderch, M de Pera, J Fonollosa, A de la Maza, and J L Parra, ‘Efficacy of stratum comeum lipid supplementation on human skin‘, Confacr Dermatitis, 2002 47 139-146. 16 M Fresta, and G Puglisi, ‘Corticosteroid dermal delivery with skin-lipid liposomes’, J. Controlled Release, 1997 44 141- 1 5 1. 17 L Coderch, M de Pera, N Pkrez-Cullell, J Estelrich, A de la Maza,and J L Parra, ‘The effect of liposomes on skin barrier structure’, Skin Pharmcol. Appl. Skin Physiol,, 1999 12 235-246. 18 Mh Schmid and H C Korting, ‘Liposomes for atopic dry skin: the rationale for a promising spproach’, Clin. Invest., 1993 71,649-653. 19 J Pinnagoda, R A Tupker, T Agner, J Serup, ‘Guidelines for transepidermal water loss (TEWL) measurement’, Conruct Dermatitis, 1990 22 164-178. 20 E Berardesca and the EEMCO Group, ‘EEMCO guidance for the assessment of stratum comeum hydration: Electrical methods’, Skin Res. Tech., 1997 3 126-132. 516 0 Woodhead Publishing Limited, 2010
PART VIII INDUSTRY STANDARDS AND REGULATIONS
DIRECTIVES, REGULATIONS AND STANDARDS FOR THE MEDICAL DEVICE INDUSTRY: AN OVERVIEW C. J. Knill and J. F. Kennedy ChembiotechLaboratories, Advanced Science and Technology Ltd, 5 , The Croft, Buntsford Drive, Stoke Heath, Bromsgrove, Worcestershire,UK
MEDICAL DEVICES IN THE EU Directive 2007/471EC of the European Parliament and of the Council of 5" September 2007 [11, which amended previous Council Directives 90/385/EEC [*I, 93/42EEC Dland 93/68/EEC [41, concerns medical devices, and Directive 98/79/EC of 27" October 1998 specifically covers in vifro diagnostic medical devices. EU Directives define a medical device as any instrument, apparatus, appliance, software, material or other article, whether used alone or in combination, including the s o h a r e intended by its manufacturer to be used specifically for diagnostic and/or therapeutic purposes and necessary for its proper application, intended by the manufacturer to be used for human beings. Devices are to be used for the purpose of: 0 0
0
0
Diagnosis, prevention, monitoring, treatment or alleviation of disease. Diagnosis, prevention, monitoring, treatment, alleviation of or compensation for an injury or handicap. Investigation, replacement or modification of the anatomy or of a physiological process. Control of conception.
This includes devices that do not achieve their principal intended action in or on the human body by pharmacological, immunological or metabolic means, but which may be assisted in their function by such means. Thus medical devices must be distinguished tiom medicinal products, cosmetics, and food products. A medicinal product is defined in the EU by Directive 2001/83EC as any substance or combmation of substances presented for treating or preventing disease in human beings. The primary effect of a medical device is therefore physical, in contrast to medicinal products such as pharmaceutical drugs, which exert a biochemical effect.
MEDICINES dk HEALTHCARE PRODUCTS REGULATORY AGENCY The Medicines and Healthcare products Regulatory Agency (MHRA)[4 is a UK government body set up in 2003 to bring together the h c t i o n s of the Medicines Control Agency (MCA) and the Medical Devices Agency (MDA). The MHRA regulates medical devices in the UK under EU legislation, which also includes equipment used in healthcare and the investigation of harmful incidents. The principal aim of the MHRA is to safeguard public health by making sure that medicines and medical devices work pro erly and are acceptably safe, and by responding promptly when new concerns arise No product is completely fiee of risk but sound scientific evidence is used to underpin MHRA decisions to ensure that such risks are minimised. The MHRA has the power to withdraw a product from the market, and prosecute a manufacturer if the law has been broken. Regulatory affairs and authority structures are obviously different in different parts of the world. In the US medical devices are dealt with by the Center for Devices and
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Radiological Health CDRH), which is a division of the US Food and Drug Administration(FDA) !81 .
In general, a medical device cannot be marketed in Europe without carrying CE marking, which is applied by the manufacturer, and certifies that the device has met EU consumer safety, health or environmental regulatoy requirements and, when used as intended, works properly and is acceptably safe 17,]. For all but the very lowest risk devices, such as medicated bandages, this must be verified by an independent certification body, called a Notified Body, before the CE marking can be affixed. The MHRA is responsible for appointing and regularly auditing UK Notified Bodies. Manufacturers should be able to provide scient5c evidence to support their performance claims for a device. In many cases, and in particular for higher risk devices, this information comes fiom a clinical trial, which in the UK has to be approved by the MHRA. SAFETY/QUALITY STANDARD MONITORING Medical devices are always tested for mechanical andor electrical safety before they are used odin people, but, d i e medicines, they are not automatically subject to a clinical trial [71. This is because it is often impractical and unnecessary to test them in this way and safety and performance can be based on laboratory tests. Whether a device is subject to a clinical trial or not depends on the type of device, its intended use, and how ‘new’/dii€erentit is. Clinical trials are phased and may take several years to complete. There are several ways in which the MHRA checks the safety and quality standards of healthcare products and ensures that they comply with EU and UK law and regulations. As well as its own inspection teams and proactive monitoring, the MHR4 relies on manufacturers, healthcare professionals, and the general public to report defects, side effects, and misleading information. When a product is suspected or known to be faulty, the MHRA immediately works with manufacturers and wholesalers on the most appropriate and timely action to take. Sometimes this means a product has to be recalled and taken out of the supply chain. By law, manufactuters must report to the MHRA any important defects in medical devices. The action taken is determined by the scale of the threat to public health. Reports prompt investigations, which can result in the issue of warningdalerts. Healthcare professionals and their patients, as well as manufacturers, can report roblems about medical devices using the MHR4 adverse incident reporting scheme . These reports help manufacturers to improve their device design and product information, and help the MHRA to improve device safety. All reports are assessed and acted upon by the MHRA, although the response is graded according to the seriousness of the incident and the potential for future harm. Such responses may be:
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a Medical Device Alert,giving advice to the healthcare service, andor a requirement for the manufacturer to make appropriate changes in device design or product information, or a product recall, or sending the data to the manufacturer and storing it in the MHRA database to spot future trends that requireaction. 520 0 Woodhead Publishing Limited, 2010
The number of medical device reports has risen over the past decade, as technology has become more complex and sophisticated, patients and professionals have been encouraged to report problems, and the number of devices in use has dramatically increased. Increased reporting reflects a high level of awareness and therefore the effectiveness of the safety monitoring system. It does not mean that manufacturing standards have fallen or that devices have become less safe, overall [I.
BIOCOMPATIBILITY TESTING In this context biocompatibility is concerned with the interaction between a medical device and the tissues and physiological systems of the patient treated with the device. An evaluation of biocompatibility is an important part of the overall assessment of the safety of a device, and is investigated using analytical chemistry, in vitro testing, and animal models. Device biocompatibility depends on a number of factors, including the chemical and physical nature of its component materials, the es of patient tissue that will be exposed to the device, and the duration of exposure [ l o . Biocompatibilitytesting is almost always required for devices that have signtficant tissue contact. IS0 10993, ‘BiologicalEvaluation of Medical Devices ’ provides detailed information to assist with understanding of biocompatibility requirements and determination of what tests are required for a particular device. Part 1 of the standard is the ‘Guidance on Selection of Tests’, Part 2 covers animal welfare requirements, and Parts 3-20 are guidelines for specific test procedures and other testing-related issues “13121. Examples of biocompatibilitytests include cytotoxicity (tissue culture), sensitisation assays, irritation tests, acute systemic toxicity, subchronic toxicity, genotoxicity, implantation tests, haemocompatibility,carcinogenesis bioassay, reproductive and developmental toxicity, pharmacokineticsstudies, preclinical safety testing, and histopathology studies [10-121.
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THE DRUG TARIFF In the UK the Drug Tariffoutlines: 0
0
what will be paid to pharmacy contractors for NHS services provided either for reimbursement (the cost of drugs, appliances etc which have been supplied against an NHS prescription) or for remuneration (what is paid as part of a dispensing contract with a local health trust for fees/allowancesetc), the rules to be followed by pharmacy contractors when dispensing, the values of the fees and allowances paid to pharmacy contractors, the drug and appliance prices paid to pharmacy contractors.
N H S Prescription Services produces the Drug Tarif€ on a monthly basis on behalf of the Department of Health, and it is supplied primarily to pharmacists and doctors’ surgeries [13]. Part IX of the Drug Tariff is concerned with medical devices, and recent changes to this part of the Drug Tariffare discussed in an article in this chapter.
REFERENCES 1 Directive 2007/47/EC {http://eur-lex.europa.eu/lexUriServ/LexUriServ.do?uri= OJ:L:2007:247:0021:0055:EN:PDF}.
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2 Directive 90/385EEC {http://eur-lex.europaeu/LexUriServ/LexUriServdo?uri= CELEX.31990L0385:EN:HTML). Directive 93/42/EEC {http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri= CELEX:31993L0042:EN:HTML}. 3
Directive 93/68/EEC { http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri= CELEX3 1993L0068:EN:HTML).
4
5 Directive 98/79/EC {http://eur-lex.europa.eu/LexUriServ/I.exUriServ.do?uri= OJ:L:1998:331 :0001:0037:EN:PDF}. 6 Medicines and Healthcare products Regulatory Agency (MHRA) {www.mhmgov.uk}. 7 Medicines & Medical Devices Regulation: Whatyou need to know, Medicines and Healthcare products Regulatory Agency (MHRA), { http://www.mhra.gov.uk/home/ groups/commsic/documents/websiteresources/con2031677.pdf). 8 T. Wehman, Regulatory Maim Medical Devices, In: The Medical device R&D H d m k (T. R Kucklick (ed.),CRC Press, Boca Raton, USA, 2006,223-266).
9 Department for Business Enterprise & Regulatory Reform @ERR) information on CE marking{h r ? : / / w w w . b e r r . g o v . u W w h a t w e d o / s e c t o r s / s u page11646.html). 10 Northview Laboratories, Introduction to Biocompatibility Testing, In: The Medical device R&D Hmuibook (T. R Kwklick (ed.),CRC Press, B- Raton,USA, 2006, pp. 267-294). 11 Biological Evaluation of Medical Devices, Parts 1-20, IS0 10993, International Organization for Standardization.
12 AAM Standarch and Recommended Practices, Vol. 4: Biological Evaluation of Medical Devices AAMVMYISO 10993, Association for the Advancement of Medical Instrumentation (AAMI), Arlington, VA, US.
13 NHS Business Services Authority {http://www.nhsbsa.~.uk/924.aspx).
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RECENT CHANGES TO THE UK DRUG TARIFF FOR APPLIANCES LISTED IN PART M G J Collyer Chairman, Sumed International Ltd, UK
INTRODUCTION Investment on research and development of new materials will only be maximised if there is a clearly established route to market for newly developed products. In the UK, the routes to market for products used in the community setting have been well established for some thirty years. Recent efficiency drives initiated by the Commercial Directorate of the Department of Health threatened to disrupt the routes to market which traditionally have meant that the UK is a place of choice for research, production and the first launch of many new technologies. This paper explores the history behind the reimbursement process for appliances in the community setting, and the consultations aimed at reviewing the arrangements for the provision of dressings, incontinence appliances, stoma appliances chemical reagents and other appliances to primary care and secondary care. Although the proccss is not yet complete, the paper sets out to update on the current position and the implications to research and development.
HISTORY TO TEE REIMBURSEMENT OF APPLIANCES Separate arrangements are in place in England, Scotland, Northern Ireland and Wales.For the purposes of this discussion, given that the recent consultations have been for England, this paper only considers the position in England. The NHS Act 1977 provides that all drugs and a list of appliances at the discretion of the then Secretary ofstate for Health will be made available h e on the NHS. Subsequent revisions have introduced the concept of a “blacklist” of drugs which cannot be provided free of charge. With regards to the list of appliances approved by the Secretary of State, this is compiled and published each month in the Drug Tariff as Part IX. The Drug Tariff is published by the NHS Business Services Authority on behalf of the Secretary of State as provided under Regulation 56 of the NHS (Pharmaceutical Services)Regulations 2005. This is split into four sections: Part IXA Appliances (this includes bandages, dressings, catheters and other appliances Part IXB Incontinence Appliances Part IXC Stoma Appliances Part IXR Chemical Reagents Responsibility for administration of Part IX of the Drug Tariff is shared between the Department of Health and the Prescription Pricing Division (PPD) of the NHS Business Services Authority. The former has responsibility for policy matters and the latter for the approval of the four separate lists on behalf of the Secretary of State for the purposes of Section 41 of the NHS Act and to determine the prices on which payments to contractors are to be based. In addition the PPD has responsibility for operating a mechanism to remove products fiom Part IX.
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When a patient is provided with a prescription by a General Practitioner or a Community Practitioner Nurse Prescriber, hdshe may take the “prescription” to either a pharmacy contractor, an appliance contractor (commonly known as a dispensing appliance contractor), or a dispensing doctor. The contractor will dispense the items listed on the prescription and receive fees for services (remuneration) and the drug tariff price for the item which has been dispensed (reimbursement). The route to market is well established and over the years stakeholders have worked towards introducing mechanisms for the quick listing of new products and for the automatic increasing of prices on an annual basis, pegged behind the future rate of GDP growth. This mechanism has been in operation for some ten years by agreement between the Department of Health and the Drug Tariff Part IX Forum (which includes BHTA, SDMA, BIVDA and ABHI). The three year agreement which came into effect in April 2003 was suspended in 2006. It allowed companies to apply for annual increases in prices no greater than the government’s published prospective GDP deflator, less a firctor X set for the purposes of the latest agreement at 0.75. As a result of this well understood route to market coupled with a mechanism for increasing prices, albeit pegged behind the rate of inflation, England has been seen as an important market for introducingnew technologies,particularly those which are suitable for use in the community setting. Recent consultationsthreatenedto disrupt this position. THE GERSHON REVIEW 2004
In July 2004 Sir Peter Gershon published an independent review of public sector efficiency entitled “Releasing resources to the fiont line”(1). This report was as a result of a request in August 2003 from the then Prime Minister and Chancellor. The report concluded that through working closely with departmentsand other stakeholders, auditable and transparent efficiency gains of over E20 billion in 2007-8 across the public sector have been identified and agreed. The agreed target for the Department of Health was for efficiency gains of around E6.5 billion by 2007-08, of which over half was to be cashable, releasing resources for h n t line activities. As part of the implementationplan the department set rxt to: 0
Achieve a total reduction of just over 720 civil service posts, reduce the staffing of anns-length bodies by at least 5,000, and be on come to relocate 1,100 posts out of London and the South East by 20 10; Make better use of stafftime (accounting for up to half of efficiencies),for example through the implementationof a modem ICT inhistructure for the NHS.Electronic patient records, appointmentsbooking and prescription transfer will mean less wasted time spent checking patient information, fewer letters to type and send, and no lost prescriptions;
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Make better use of NHS buying power at a national level to get better value for money in the procurement of healthcare, facilities management and medical supplies;
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Ensure NHS organisations, particularly in primary care, can share and rationalise back office services, such as finance, ICT and human resources, where possible; and
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Improve commissioning of social care to generate around 10 per cent of the efficiencies.
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As a result of the Gershon Review the Commercial Directorate of the Department of Health was established and The Supply Chain Excellence programme was initiated.
THE SUPPLY CHAIN EXCELLENCEPROGRAMME Launched in March 2004, SCEP set out to achieve savings of more than E500million p r annurn by 2007/8 by improving NHS procurement and supply chain activity. The four strands of the initiative were: 0
National Contracts Procurement where E240 million of savings were targeted from f4 billion of NHS PASA influenceable spend, improving sourcing of national products through new national framework agreements, and encouragingtrusts to use the new agreements CollaborativeProcurement Hubs where savings of E270 million were targeted fkom regional NHS spend of circa E l 1 billion.
0
NHS PASA reorganisation
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NHS consumables supply chain and procurement service. Here the intention was to establish whether the most effective supply chain and procurement service for the NHS can be achieved by partnenng with the independent sector
NCP activity was split into two waves of activity with the first wave being completed by January 2005 and the second wave commenced in August 2005. Wave 1 addressed:
0
0 0
Agency temporary staff Medical Consumables Food Furniture Generic Pharmaceuticals Stationery Fleet cars
Wave 2 set out to cover: 0 AgencyLabour 0 Laundry Telecom (voice)
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Recruitment advertising Pressure area care (therapeutic beds) Incontinence care home delivery
Categories subject to a fiuther checkpoint before full implementation: ICDs and pacemakers Lab pathology equipment and reagents Diagnostic equipment maintenance Subject to market consultation: 0 Items within part 9 of Drug Tariff The First Consultation: 2 4 ' October 2005: Arrangements for the b v i s i o n of Dressings, Incontinence Appliances, Stoma Appliames, Chemical Reagents and Other Appliances to Primary and Secondary Care. Closed on 2 p January 2006. This consultation proposed a two stage process. In the first stage the department proposed to adjust item prices to reflect what it defined as market pices and to remunerate appliance contractors at or near to the current basis for pharmacy contractors. In the iirst stage it proposed to immediately reduce the prices of all dressings including other appliances (catheters) by 5%, and incontinence applianaes, stoma appliances and chemical reagents by 15%. After these reductions, the consultation document claimed that the resultant prices would still represent a premium over market prices. In the first stage appliance contractors who receive approximately 18% of net ingredient cost were set to have their fees reduced to around lo%, the level paid to pharmacy contractors. The second stage proposed one of five ways forward- the purpose of the consultation: 0 Set item prices by tender for primary care and secondq care combined. A preferred supplier would be established and all products would be reimbursed at the price of the preferred supplier. 0 Set item prices in the primary care sector (the Drug Tariff)by specialists who identify which products are functiondy equivalent. Secondary care prices would be set through a re-tendering process. 0 Set item prices in the primary care sector (the Drug Tariff)based on the underlying costs. Secondarycare prices would be set by tender. To establish service remuneration raes for specific services in primary care 0 Donothing There were over 2,200 responses to this consultation which closed on 2 9 January 2006.Of these 1,946were from patients and 56 were from nurses. The conclusion from the consultation was that concern MS expressed at the comparison of prices in the primary care and secondary care markets and how the proposed percentages for the first stage had been anived at. In addition very few people believed that it would be possible for appliance contractors to carry on trading were they to be remunerated at similar levels to pharmacy contractors. Many respondents disagreed with a two stage approach stating that this would result in uncertainty and instability in the market place. There was a strong feeling that a q changes which were to be introduced should be done so in one stage after consultation with industry.
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The outcome of the first consultation was that the Department proposed to have further discussion with industry and patient groups to identify how best to achieve transparency between item price and service costs in the areas of incontinence and stoma appliances. It flagged that it would consult again with the market in the areas of dressings and reagents in each case looking at a subset of products. The Second Consultation : 8" May 2006.Arrangements for the Provision of Dressings and Reagents to Primary Care. Closed on d'June 2006. For dressings where the first proposal was to cut prices in the first stage by 5% across the board, the new consultation proposed the reduction of a list of products resulting in savings of E6 million in sales in the category of El39 million, 4.3%. The revised proposal did not propose changes to the more modem products, with no decrease for some products, but as much as a 78% decrease in price for Gauze Swab Type 13 Light BP 1988,Non Sterile where the proposal was to reduce the price from E5.73 to E1.26. For Reagents where the first proposal was to cut prices in the first stage by 15% across the board, the new consultation was restricted to Detection Strips, Blood for Glucose. It excluded Detector Strips Urine, Detection Strips Blood for Ketones and Detection Strips Blood for Determination of International Normalised Ratio. It suggested that there were savings of El9 million on a total spend of f128 million, 14.8%. For all products within Detection Strips, Blood for Glucose the consultationproposed a 15% reduction in the price. There were 63 responses to the consultation with only 2 from patients and 4 fiom nurses. The most responses were received from manufacturers where 19 responses were received. The outcome of the consultation was that the prices of the majority of dressing were reduced by the amounts proposed on ''1 October 2006. For Reagents, where the Prescription Cost Analysis showed that blood glucose strips had cost the NHS E15,000 or less in 2004 prices were left unchanged. For all other blood glucose strips 12% price reductions took effect ftom 1" October 2006 with the threat that a further 3% cut would be imposed on 1" November 2006 if companies decided not to continue to provide free services such as the provision of meters and an identifier would be attached to the drug tariff entry alerting the prescriber to the fact that the patient would need to purchae their own meter. Although no further price reductions have been imposed, at least one product is in the process of being withdrawn ftom the market. The Third Consultation: 2 7 July ~ 2006. Arrangements for the provision of stoma and incontinence appliances and related support services to patients under Part M of the Drug Tariff. Closed on 1 I* September2006. This consultation was split into two different parts, service standards and categorisation. For service standards, the consultation stated that the Department wished to ensure equity, consistency and quality in the provision of appliances and proposed amendments to the contractors' terms of service within the Pharmaceutical Services Regulations such that two levels would be. introduced: essential and additional. Essential Services were to include dispensing, repeat dispensing, provision of complimentary supplies, product delivery and a telephone care line. Additional services were to include customisation and a telephone care line. As regards product classification the consultation proposed an enhanced classification system which would allow hctionally equivalent products to be grouped together in distinct subcategories. It stated that this classification system would be used to compare
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the prices of functionally equivalent products while helping prescribers identify functionallyequivalent products. There were 51 responses to the consultation which included none h m patients and 2 fiom nurses. As an outcome the Department stated that it intended to consult further in November 2006 on the pricing of services and the suitability of the Drug Tariff reimbursement prices for stoma and incontinence appliances under the alternative classification structure. It indicted that there would be changes in tEe service specifications intheareasof: 0 Issuing supplies without a prescription Reminder services provided by conkactors Product delivery of stoma items 0 Provision of complimentary supplies with stoma items dispensed Provision of clinical information either via a telephone care line or facsto-face 0 Customisationof stoma appliances 0 Specialist nurse visits Elated to stoma items dispensed. As regards the classification of products it was proposed that products be classified as regards similar medical need as opposed to functional equivalence. The Fourth Consultation: 23d November 2006. Arrangements for the reimbursement pricing of stoma and incontinence appliances under Part IX of the Drug Tariff. Original response date March 2007 later extended to 2"dApril 2007. The consultation grouped N u c t s into products offering similar medical needs in sub categories and then using the mechanism set out below proposed to rebase prices. After excluding low volume products defined as those with a market share of less than 0.1% the product with the lowest price was deemed to be the benchmark price. Any product within the sub-category with a price higher than 200h more than the benchmark price (including low volume excluded items) would then have its price reduced to 20% more than the benchmark. The proposal suggested E22 million out of E82.5 million on urology appliances, 26.7%and €8 million out of El44 million on stoma appliances, 5.6%. The outcome of this consultation is not yet h o r n but an indication has been given that although changes were to have been implemented with effect from June 2007, it is unlikely that changes will be made durin 2007. The Fifth Consultation: 239November 2006. Arrangements for the reimbursement of services relating to appliances under Part IX of the Drug Tarif€. Original response date sh March 2007 later extended to YdApril 2007. This consultation proposed some significant changes to the remuneration of dispensing appliance contracton. All dispensing appliance contractors would receive an inhstmctwe payment dependent on the number of prescriptions dispensed in a month. For stoma products only, contractors would be paid a standard fee for dispensing an item and a fee for the provision of a home delivery service. In addition, they would receive a customisation fee and a fee for providing specialist visits. For incontinence products and any other appliances, only the standard fee for dispensingwould be paid. The outcome of this consultation is not yet known but an indication has been given that although changes were to have been implemented with effect from June 2007, it is unlikely that changes will be made during 2007.
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CONCLUSIONS Research and Development is maximised where markets can be clearly defined and the routes to market are transparent and ensure that launch at an appropriate price point in a reasonable time h m e will be possible. In England, the Drug Tariff has been structured for many years such that companies will invest in the UK. Recent challenges to thepricing of existing products and the ongoing mechanism for product availability and pricing have destabilised a number of subsets of the appliance market but although the consultation process is not complete in all areas, considerable progress has been made in ensuring that England will remain an area where R&D expenditure will continue to be invested
REFERENCE 1 Published with permission of HM Treasury on behalf of the Controller of Her Majesty’s Stationery Office www.hm-treasury.gov.uk/rnedia/B2C/11/efficiency-reviewl20704.pdf
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