Textiles in Medical Science

Abstract:

             Globalization of world market has put a sufficient pressure of textiles manufacture to think about their survival. Changing scenario demands change in approach to diversification of product. Now textiles does not means only looking fashionable and covering body, but also it can be more functional and use for technical applications like agriculture , aerospace, geo textiles, medical textiles and etc,. The medical textiles are one part of technical textiles, it is an interdisciplinary field and it’s collaborated between medical and textile sectors.

          Medical science has become very advanced from last few decades. More and more techniques are invented to procure better health methods. Use of medical textiles for replacing damaged tissues or organs is the result of advanced medical invention. However substitute for defective body parts was used to be transplantation of that part or organ, but this is not always possible. Thus use of textiles as a substitute to replace and aid for damaged body parts is being utilized by the surgeons and physicians.

        In this paper, discussed about the application of textiles in various medical fields namely, health care, hygiene products, extra corporeal devices and surgical textiles, Non implantable and implantable materials, Phase Change Materials and Super Absorbent Fibers in these felids.

Introduction:

The term “medical textiles” literally means textiles used for medical purposes. Textile apart from being a vital part of human life are since long been used in medical field, though the tern has been coined very recently. Textile materials have a range of properties such as flexibility, elasticity, strength, etc. based on these properties research work has been going on rapidly around the world towards the application of textiles in medical field. Specialist from physicians to textile chemists and textile engineers are ready to devote themselves unitedly to apply these broad ranges of properties of textile material in medical technology ^(1).

Categories of Medical Textiles

Surgical Sutures ⁽²⁾

Fibers are also used as sutures in surgery. Sutures are sterile filaments which are used to hold tissues together until they heal adequately or to join tissues implanted prosthetic devices., Sutures are either braided or monofilament are mostly used to close wounds and approximate tissues. The textile materials have generated considerable interest in medical technology where materials in the form of monofilament, multifilament, woven and nonwoven structures are being used for bio and medical applications. The major requirement of the textile materials is the bioreceptivity and biocompatibility at the application site in human being. The medical textile group in the Department of Textile Technology at IIT Delhi has been working on the development of antimicrobial biocompatible sutures and scaffolds for tissue engineering. Because of the lack of proper post-surgical care, the bacterial infection in stitched wounds is prevalent in many of the cases.   

                                                                     

The development of an antimicrobial suture based on Nylon and Polypropylene monofilaments is being pursued in the Medical Textile group. The surface functionalization of the suture is carried out in such a way that the inherent characteristics, such as mechanical and knot strength of the suture are not affected. Both the high energy gamma radiation and the plasma irradiation are being used to activate the materials for the surface functionalization. An antimicrobial drug is immobilized on the suture surface which subsequently is released slowly into tissues surrounding the stitch and prevents the microbial invasion. The tissue compatibility of these sutures is excellent and no adverse reaction has been observed against these sutures.             Fig: 1 Surgical Suture Process

Barbed Sutures

Recently a bi-directional barbed suture has been developed which obviates the necessity to tie a knot. It has ability to put tension in the tissues with less suture slippage in the wound, as well as to more evenly distribute the holding forces there by reducing tissue distortion. The barbed suture with a steeper cutangle and a median cut depth have a higher tissue holding capacity than those with a moderate cutangle and a nominal cut depth.                                    Fig: 2 Barbed Suture Needle

GELATIN COATED SUTURES

Gelatin coated sutures are having a superior handling characteristics. The gelatin coating given to the suture material improves the surface smoothness and reduces the fraying characteristics. It can be obtained by means of treating the suture with that of aqueous solution of gelatin to coat the suture and it is made to have a contact with that of fixative agent to crosslink gelatin. This process includes the step of contacting the coated suture with that of buffer solution and heats it to 50⁰C for a particular period of time interval. Usually heating can be carried out for about 1-20hrs. Sometimes plasticizers can be incorporated into the gelatin solution. The plasticisers used are triethyl citrate, glycerin or other poly hydric alcohols. The plasticiser used is mainly to enhance the benefits of the gelatin coating. The fixative solution used in the process is a cross linking agent. The preferred cross linking agent is preferably a dialdehyde such as glyoxal, which may be used alone or in conjunction with formaldehyde or other aldehyde.

Dressing Materials ^{(3 &4)}
Calcium Alginate Fibers

The raw material for the production of this fibre is alginic acid, a compound obtained from the marine brown algae. It has a variety of properties, including the ability to stabilize viscous suspension, to form film layers, and to turn into gels. When the dressing made of this fibre is applied to wound, the reverse ion exchange take place, and this fibre is placed on the wound in dry state and begins to absorb the exudates. The calcium ions are then gradually exchange against sodium ions that are present in the blood and wound exudates.

The fiber absorbs large amounts of secretion, starts to swell and in the presence turns into a moist gel that fills and securely covers the wound. Both the extent and the rate of gel formation depend on the available amount of secretions. The more exudates present the more rapid gel formation occur. Addition of excess sodium ion causes further dissolution of the gel, so that calcium alginate fibres remaining in the wound can be resorbed. If necessary, but mayh also without problems be rinsed out with physiological saline solution.

Sorbalgon

It is a supple, non-woven dressing made from high quality calcium alginate fibre with excellent gel forming properties. The dressing offers number of practical therapeutic advantages for wound healing over any other commonly uses textiles. A Sorbalgon dressing absorbs approximately 10ml exudates per gram dry weight and thus provide with an absorption capacity. They in addition differ from textile dressings with respect to applied mechanism of absorption. It takes wound secretion directly into the fibres i.e., using intra capillary forces.                                                            

Super Absorbable Polymer

Super absorbents are swell able cross linked polymer, which have the ability to absorb and store 400-600 times there own weight of aqueous liquid by forming a gel. The liquid is then retained and not released, even under pressure. The absorption rate of the polymers differs according to their mechanism used for preparation. SAP cannot dissolve because of their 3-D polymeric network structure of the many different types of polymers, only a few can be made into useful fibers. This is because a polymer must meet certain requirements before it can be successfully and efficiently converted into a fibrous product. Some of the most important of these requirements are:

·  Polymer chains should be linear, long, and flexible. Side groups should be simple, small, or polar.

·  Polymers should be dissolvable or melt able for extrusion.

·  Chains should be capable of being oriented and crystallized.

Common fiber-forming polymers include cellulosic (linen, cotton, rayon, acetate), proteins (wool, silk), polyamides, polyester (PET), olefins, vinyls, acrylics, polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), aramids (Kevlar, Nomex), and polyurethanes (Lycra, Pellethane, Biomer). Each of these materials is unique in chemical structure and potential properties. For example, among the polyurethanes is an elastomeric material with high elongation and elastic recovery, whose properties nearly match those of elastin tissue fibers. This material when extruded into fiber, fibrillar, or fabric form derives its high elongation and elasticity from alternating patterns of crystalline hard units and noncrystalline soft units. Although several of the materials mentioned above are used in traditional textile as well as medical applications, various polymeric materials both absorbable and nonabsorbable have been developed specifically for use in medical products.

The reactivity of tissues in contact with fibrous structures varies among materials and is governed by both chemical and physical characteristics. Absorbable materials typically excite greater tissue reaction, a result of the nature of the absorption process itself. Among the available materials, some are absorbed faster (e.g., polyglycolic acid, polyglactin acid) and others more slowly (e.g., polyglyconate). Semiabsorbable materials such as cotton and silk generally cause less reaction, although the tissue response may continue for an extended time. Nonabsorbable materials (e.g., nylon, polyester, and polypropylene) tend to be inert and to provoke the least reaction. To minimize tissue reaction, the use of catalysts and additives is carefully controlled in medical-grade products ^(5).

Water Absorbent Polymer

Water absorbent polymers are known as hydro-gel, water crystal, super absorbent polymers etc., are simply a type of plastic that possesses some unique water absorbing qualities. This is due to the presence of sodium or potassium molecules that form bridges between the long hydro carbon chains. These bridges are known as cross linking, which enables the polymer to form into a huge single super molecule, including its ability to degrade in the environment and breakdown into simpler molecules, and hold significant amount of water. When water comes in contact with super absorbent an electrical repulsion takes with in the particles. When this happens, water is drawn into the particles resulting in swelling of each particle. At maximum absorption capacity each particle will expand to over 30 times its original volume. When water evaporates it shrinks, returning to unswollen state.

Spider Silk

Modified goat milk will contain web protein .A goat that produces spider's web protein is about to revolutionist the materials industry. It is Stronger and more flexible than steel, spider silk offers a lightweight alternative to carbon fibre. Up to now it has been impossible to produce "spider fibre" on a commercial scale. Unlike silk worms, spiders are too anti-social to farm successfully.                                              Fig: 4 Spider silk (Spinners)          

 Now a Canadian company claims to be on the verge of producing unlimited quantities of spider silk - in goat's milk. Using techniques similar to those used to produce Dolly the sheep, scientists at Nexia Biotechnologies in Quebec have bred goats with spider genes. New kids on the block Called Webster and Pete, the worlds first "web kids" cannot dangle from the ceiling, nor do they have a taste for flies. In fact they look like any other goat. But when they mate, it is hoped they will sire nanny goats that produce milk that contains the spider silk protein. This "silk milk" will be used to produce a web-like material called Biosteel. Naturally occurring spider silk is widely recognized as the strongest, toughest fibre known to man.                                                                                 

Its tensile strength is greater than steel and it is 25 percent lighter than synthetic, petroleum-based polymers. These qualities will allow Biosteel to be used in applications where strength and lightness are essential, such as aircraft, racing vehicles and bullet-proof clothing. Kind to humans another advantage of spider silk is that it is compatible with the human body. That means Biosteel could be used for strong, tough artificial tendons, ligaments and limbs. The new material could also be used to help tissue repair, wound healing and to create super-thin, biodegradable sutures for eye-or neurosurgery ^(6).

Antimicrobial Fiber

Antibacterial fiber is produced by entrapping the metal ion with a cation exchange fibre having a sulphonic or carboxyl group through an ion exchange reaction. The antibacterial metal ion is silver or silver in combination with either copper or zinc. The great advantage of this material is that those are not to react with tissue. Flexible products such as sponges and textile wites, which have protracted antimicrobial effect. The wipes are impregnated with biocides by spra8ying, dipping or soaking for use in medical field.

Acticoat Dressing

It provides broader and faster protection against fungal infection than conventional antimicrobial products. The dressings are layered with mono crystalline silver known to have antimicrobial and antifungal properties, creating a protective barrier as silver ions are consumed. Acticoat has the faster kill rate and was effective against more fungal species. The product can be applied to variety of wounds including graft and donor sites and surgical wounds.

Antimicrobial Wound Dressing

Kerlix AMD is pure cotton treated with anecia's polyhexamethylene biguandine agent. These antimicrobial agents resist bacterial growth with in the dressing as well as reducing bacterial penetration through the product. Wound covering, is made of a hydrophobic bacteria-adsorbing material which comprises the antimicrobial active component which is not released into wounds, it is preferably made of mixture of hydrophobic fibres and fibre comprising antimicrobial property ^(7).

Phase Change Materials (PCM):

Phase change technology in textiles means incorporating micro capsules into textile structures. Phase change materials (pcm) are used in health care applications for faster recovery of patients. These are the material that possesses the ability to change their physical state from solid to liquid or vice- versa, within a certain range of temperature. The energy required for breaking the bonds and changing from solid to liquid is absorbed from the surroundings. During the entire phase change the temperature of the surrounding substrate and the pcm remains constant. These pcm’s can be used in micro encapsulated form for surgical clothing, bedding material and intensive care material purposes. Microfibres, non woven and their composites are used in drapes, gowns, caps, mask, etc. due to their dispesability, barrier properties, breathability, drapeability, strength, softness and comfortability. A British company has developed a special bra, called “mamo test bra”, which can detect breast cancer at a very early stage. The black bra is coated with thermochrombic liquid crystal ink, which changes color with the amount of heat. It is subjected to the cancerous tumours are warmer than the adjacent areas and can be detected by different color patterns ⁽⁸⁾.

Disposable Products:

Absorbent disposable products, such as diapers, sanitary napkins, tempons, incontinence products, panty shields, wipe, etc. are mostly single use items and are designed to receive, absorb and retain body fluids and solid waste. The disposable diaper for baby care was first marketed in Sweden in the late 1930’s. and the present all-in-one diaper consists of multilayer components with an enhanced facility to collect urine and faucal waste and incorporates a super absorbent polymer as an absorbent component.

A modern breathable disposable feminine product consists of three layers, of which the inner top layer is made of a blend of hydrophobic (polyester), low density fibres (polyethylene) and is liquid and water permeable. The core layer, packed with wood- pulp as other absorbent materials, is highly absorbent and the third layer consists of a multi layer barrier, that is water vapour permeable, but resistant to liquid water. It is of interested to note that fibers obtained from gellan gum are utilized for making tempons. The gum is obtained from the culture of pseudomonas elodeabacterium by fermentation. A washable or disposable nursing pad has been developed to absorb breast milk leaking from a nursing mother into her outer garments, principally during the night.

 A modern incontinence product also consist of three layers, a cover stock, that is permeable and diffuses the liquid laterally, a highly absorbent core, and a barrier polyethylene or polyvinyl chloride film that helps the patient clothes or bedding to keep dry ⁽⁹⁾.

Smart Textiles for Health Care:

Intelligent or ‘smart’ textile is an emerging field in textile research, where the material is designed to sense and react to different stimuli or environmental conditions. The extent of intelligence can be divided in three sub- groups; passive smart, active smart and very smart textiles. An important development applicable to the medical field is the ‘wearable computer system’. For example, a smart t- shirt with conductive fibers capable

Fig: 4 Schematic of an embedded network of processing element in a textile fabric for health monitoring

Of feeding sensor signals into a small transmitter has been manufactured. Such apparel capable of recording, analyzing, storing, sending and displaying biofunctional data including internet connectivity can be used to monitor the health status of the wearer. The first textile material that, in retroaction, was labeled as a ‘smart textiles’ was silk thread having a shape memory.

Smart t-shirt was originally designed for combat soldiers in the military to detect the location and severity of wounds and subsequently to monitor their physiological state, and to transmit the information to remote medical sites. The concept was later extended to medical applications in which the transmission of data from such a’ wearable computer’ enables the remote monitoring of heart beat, blood oxygen level, respiration and body temperature to start with. The health status can also be interpreted and transmitted to a doctor’s office or to a hospital monitoring system as required. Such a’ smart’ system can also be used for monitoring babies considered at risk for sudden infant death syndrome. Keeping watch on post- surgical geriatric patients at home, remote monitoring of stroke patients in bed , tightness of pressure garments, heat stress suffered by fire fighters and three dimensional scanning and medical imaging of patients.

The concept of smart textiles is also being extended to new finishes, for example, to provide vitamins to the body through garments, termed as ‘wearable vitamins’. Fuji spinning has developed a finish to fix pro-vitamins to fibres in a staple manner. A finished t-shirt, containing vitamin C and also E now, has been developed ^(10).

Compression Bandages

The basic function of bandages is compression, retention and support. This is obtained by properties intrinsic to the component and further enhanced and re-enforced supportively by the process of weaving and finishing relevant to the required end use. The regulation of the blood flow and prevention of swelling is closely interlinked with this property and there by enhancing improved healing healing process. It provides necessary support to restrict movement and speed up the healing process ^(11).

Conclusion:

Thus the application of textile in high performance and specialized fields are increasing day by day. There will be an increasing role for medical textile in future. Thus the textile will be used in all extra corporal devices, external or implanted materials, healthcare and hygienic products. Textile materials continue to serve an important function in the development of a range of medical and surgical products. The introduction of new materials, the improvement in production techniques and fiber properties, and the use of more accurate and comprehensive testing have all had significant influence on advancing fibers and fabrics for medical applications. As more is understood about medical textiles, there is every reason to believe that a host of valuable and innovative products will emerge; in future many more developments will happen in medical textiles particularly Phase Change Materials and Super Absorbent Fibers.

References:

1. A.A.Desai, “Biomedical Textiles” Journal of Textile Association  Jan –Feb 2004
2. Indian Journal of Fiber and Textile Research, Vol. 31, Pp 215-229.
3. Somasundram D &Kothari V K (2007) “Textile Materials in Implantable Medical Surgeries” Indian Textile Journal July Pp 73.
4. Krishnabala S. & Thangeswaran P. (2005) “Biomaterials in Medical Applications” Asian Textile Journal, Vol. 14/6, Pp 57-61.
5. Hayavadana J et. al, “Biomedical Textiles” Asian Textile Journal, February (2004), Pp 93-98.
6. I.V. Walker,  proceedings of Medical Textile Conference., 1999, Bolton  Institute, U.K., Publishing Co., Cambridge, Pp 12- 19
7. Rigby A.J et. al, Medical Textiles, Textile Horizon March 1999
8. S. Anand, ‘Medical Textiles’, Wood head publishing Ltd, Abington, 2001.
9. Opportunities for healthcare and medical textiles growth’, Technical Textiles Inter­national, 2003
10. Alistan. et. al, Hand book of Technical Textiles, Wood head Publishing Limited – England PP 412.
11. M.R. Ten Breteler et. al “ Textile Slow-Release Systems With Medical Applications” Autex Research Journal, Vol. 2, No4, December 2002