Emergence of medical textiles

Medical textile market in India is estimated to be `47,700 crore and is expected to grow by over 15 per cent in the next five years, say Neha Junare and Prem Viswanath.

With the emergence of various researches in medical field on the usage of textiles, the textile has found their application in variety of medical functionalities. Apart from medical textile confined to apparel, textiles in form of fibre or yarn or fabric are used in various medical roles via implants, blood filters, dressings, bandages, etc. The medical textile must protect the user from any type of infections where it is from contaminated fluid or contaminated air. The textile material once used, according to its characteristics and functionalities it can be either reused or disposed off. The textile material in the fabric form can be either woven or knitted fabric manufactured using natural or synthetic fibre selected as per their bio-textile application in healthcare.

With the rising standards of living, higher expectations of quality of life, changing attitude towards health, population growth in developing countries like India and with emergence of new innovation and technology the market of medical textile is growing day by day. Innovation and research and development work is carried out by various government organisations and private institution and also by large companies privately have helped in developments in medical textile field.

Materials in meditex

Textile material has a wide range of applications in healthcare and medicine – implantable products such as sutures, vascular grafts, artificial ligaments and tendons, heart valves many more. Non-implantable products such as wound dressings, bandages plasters absorbent pads cast and braces and many more. Extra corporeal product such as artificial lung, artificial kidney, artificial liver and many more. Hygiene product such as sanitary napkins, baby diapers, hospital beddings, healthcare professional apparel and many more.

Textile material used in implantation comes in contact with blood, cells tissues and body organs are known as biomaterials. The biomaterials used in implantable products are of major concern due to its contact with the body surface on implanting and its reaction with it. The biomaterial used in implantation must have following characteristics:

• Biocompatible: The material must be tested for the result of it on implanting in the body. It should not cause any harm to the body.
• Non toxicity: The biomaterial must be non-carcinogenic, non-allergic and non-pyrogenic to the implanted body.
• Sterilised: The biomaterial must be sterilised to prevent any infection and contamination with bacteria virus and pathogens to the patient and the healthcare professional.
• Non thrombogenic: The bio material must not cause clotting of blood when it contacts the blood.
• Non Mutagenic: The biomaterial must not cause any variation in the genes genetic material i.e. DNA of the patient.

Forms of material in meditex

The textile material in healthcare and medicine can be used mainly in three forms:

• Fibre form: Obtained naturally or artificially. Natural fibres include cotton wool silk and artificial fibres include polyester, polypropylene.
• Yarn form: Staple yarn; twisted yarn; braided yarn.

Fibres in meditex

Fibres used in medical textile are classified as:

• Degradable fibres: The fibres which absorbs in the body within two to three months of implantation. Examples are cotton, viscose, chitin, collagen.
• Non-degradable fibres: The fibres which get degraded by the body in more than six months, generally these fibres are synthetic fibres. Examples are polyester, polypropylene, poly-tetra-fluroethylene.
• Re-absorbable fibres: The textile fibre which is completely biodegradable by body and produce no harmful degraded product. Examples are polyglycolic acid, polylactic acid, polydioxanone.

Special medical textile fibres

Alginate: Alginate is a natural polymer that exists widely in many species of brown seaweed. The biological function of alginates is to give strength and flexibility to the algal tissue and regulate the water content in the seaweed. It is these properties along with the ability to produce fibres from its isomers, which make Alginate the ideal wound dressing.

Alginate is a natural polysaccharide exhibiting excellent biocompatibility and biodegradability, having many different applications in the field of biomedicine. Alginate is readily processable for applicable three-dimensional scaffolding materials such as hydrogels, microspheres, microcapsules, sponges, foams and fibres. Alginate-based biomaterials can be utilised as drug delivery systems and cell carriers for tissue engineering. Alginate can be easily modified via chemical and physical reactions to obtain derivatives having various structures, properties, functions and applications. The use of alginate and its derivatives in the field of biomedical applications, including wound healing, cartilage repair, bone regeneration and drug delivery, which have potential in tissue regeneration applications.

Alginate-based wound dressings such as sponges, hydrogels and electrospun mats are promising substrates for wound healing that offer many advantages including hemostatic capability and gel-forming ability upon absorption of wound exudates. Alginate was found to possess many critical elements desirable in a wound dressing such as good water absorptivity, conformability, optimal water vapor transmission rate, and mild antiseptic properties coupled with non-toxicity and biodegradability.

Based on the advantages of alginate and water-soluble chitosan, a composite polysaccharide sponge was fabricated, resulting in an anti-adhesive and antimicrobial wound dressing. Alginate-based biomaterials are promising substrates for tissue engineering with the advantage that both drugs and cells can be readily integrated into the scaffolding matrix. Alginate was combined with chitosan and silver nano-particles to form an antibacterial wound dressing.

Chitin/chitosan: Chitin is one of the most abundant natural polymers, which contain amino sugars. Amino sugars are the basic structure in most of the lubricating fluids in the body, in the basement membrane, which organises cells into tissues and in other bio molecules. The raw material, which is chosen to make chitin fibre, is mainly from the abandoned shrimp and crab chitin. The technical process is as follows: Shrimp, crab -> chitin powder ->toluene sulfonic acid’s isopropyl alcohol solution -> LiCl dimethyl acetamide -> wet spinning -> dry spinning -> chitin fibre.c Because of strong reactivity, non-toxic property, tasteless, anti-alkali, anti-corrosive, biodegradation, good biological activity, biological compatibility, binding property, softness, antibacterial property and so on, the chitin fibre can be used as the suture line, the artificial skin and the wound wrap material. A naturally occurring antibacterial agent can be derived from chitosan obtained from the crab shells. The agent has been found to be effective against the bacteria. Also it is capable of preventing the formation of offensive odors and of curing athlete’s foot.

Collagen: Collagen is a protein fibre of biological origin obtained from bovine skin. It is the principal structural protein in the vertebrate body. It has an excellent biocompatibility, which makes it a popular choice as a major component of artificial tissue and wound dressings. Recently, use of collagen as a carrier for drug delivery has attracted many researchers throughout the world. Collagen-based drug delivery systems include injectable microspheres based on gelatin (degraded form of collagen), implantable collagen–synthetic polymer hydro gels, and interpenetrating networks of collagen and synthetic polymer collagen membranes for ophthalmic delivery. Resorbable forms of collagen have been used to dress oral wounds, for closure of graft and extraction sites and promote healing.

Super absorbent fibres: Super absorbent fibres can be made from SA polymers. By comparison conventional wood pulp and cotton filler absorbents absorb only six times their weight. Normally SA polymers are not used alone but are combined with other material to form a capable of absorbing liquids. SA fibres have advantages over SA polymers in particulate form notably their high surface area, fast absorption rate, flexible handle and ease with which soft products can be formed into different shapes to fit the surface of the wound or the body.

Super absorbent fibre can be manufactured in two ways – by modification of existing fibres or polymers, and by using super absorbent polymers.

By modification of existing fibres or polymers:

• In this method, fibres are modified by hydrophilic modification i.e. incorporating hydrophilic polymers in the existing fibre forming polymers. Most of the super absorbent fibres are produced using super absorbent polymer.
• By using super absorbent polymers: Super absorbent polymers are the polymers, which can absorb high amount water/liquid and retain them. It can absorb up to 500 times of its own weight of water. Super absorbent polymers are cross-linked so that they are insoluble in the liquid which they absorb because the liquid absorbed should be retained strongly and exertion of pressure should not cause the liquid to move out.

Polylactic acid fibre: The starting point for making PLA is the sugar found in cornstarch. This is fermented to form lactic acid. The lactic acid is then polymerised to form the chains, yielding PLA. The technical process is as follows: Corn?starch -> microorganism ferments or synthesis -> lactic acid -> polymerisation -> polylactic acid -> spinning -> polylactic acid fibre. Such kind of fibre can widely used in medical suture line, implantation material of surgical operation, artificial blood vessel, disposable product like diaper and woman sanitary napkin.

Implantable products: Medical textile has a major role in manufacturing of implantable products. This includes:

1) Sutures: These are used to close the wound, join the tissue and tie the bleeding vessel. Material used for it can be mono or multifilament thread made up of collagen, PLA, PGA, catgut etc. The sutures can be absorbable which are used internally and non-absorbable sutures which are used externally, these are made up of PTFE, Polypropylene, silk etc. these are majorly used for oral incisions where it can be removed easily. 2) Tendons and ligaments: Tendons are those which connect muscle to the bone and ligaments are which connect bone to bone. When these get damaged textile materials of ultimate strength, modulus, flexibility can be used for replacing tendons and ligaments. The major requirements in artificial tendons are tissue compatibility, fatigue resistance, porosity, tensile strength and flexibility. Examples include polyethylene, carbon ligaments. The major requirements in artificial ligaments are high tensile strength, high elongation and correct stiffness to match the compliance ligament. 3) Artificial Vascular Grafts: Grafts are usually of tubular shape. They are inserted to bypass the blockages and restore the circulation. For instance – arteries of leg of diabetic patient have a tendency to be blocked. Materials used for the grafts are PTFE, polyester, polypropylene, etc. The fibrous structure of the grafts must possess some sufficient porosity to promote the tissue growth and form a thin fibrin base blood clot resistance layer on the inner surface of the graft. Body organs can be repaired by mesh grafts. These are made up of fabric having very open net like structure with high porosity throughout fabric evenly spaced net.

Tissue engineering

Tissue engineering is evolved from the field of biomaterials development and refers to the practice of combining scaffolds, cells, and biologically active molecules into functional 3D tissues. The goal of tissue engineering is to assemble functional constructs that restore, maintain, or improve damaged tissues or whole organs. Artificial skin and cartilage are examples of engineered tissues that have been approved by the FDA. This field involves scientific areas such as cell biology, material science, chemistry, molecular biology, engineering and medicine.

Scaffolds

A major goal in TE is the design of scaffolds capable of recreating the in vivo microenvironment, which is mainly provided by the 3D Extra-Cellular Matrix [ECM]. Thereby, these structures should incorporate the appropriate biophysical, biomechanical and biochemical cues that guide cell proliferation, differentiation, maintenance and function. Regarding biophysical signaling, an essential function of the ECM is to give anchorage to cells. Indeed, the ECM highly porous nanostructure provides them a proper 3D microenvironment and imparts biochemical signaling. As a result, ECM is dynamically-integrated with intracellular signaling pathways that regulate gene expression and participate in cell phenotype determination

The cells are able to sense the matrix stiffness, which results in mechanical signaling. Due to the complexity and interaction among all these cues, TE focuses on mimicking the most relevant ECM properties to develop scaffolds custom tailored depending on the tissue to be recreated. Scaffold designed must be biocompatibility and biodegradability; allowing scaffold replacement by proteins synthesised and secreted by native or implanted cells. Besides, the material must be clinically compliant to minimise inflammatory and immunological response avoiding further tissue damage. Scaffolds for TE can be divided in natural and synthetic, depending on its origin. Natural scaffolds are readily accessible and provide a broad range of cues that in vivo participate in the process of morphogenesis and function acquisition of different cell types. On the other hand, synthetic scaffolds can be custom tailored to mimic specific ECM properties, providing controllable cellular environments

Cells

An important decision to make when designing strategies for TE is the cell source selection. This step becomes a critical issue especially when these strategies are designed to be clinically applied. Importantly, cells should fulfill a basic requirement: integrate themselves in the specific tissue and secret various GF and cytokines that activate the endogenous tissue regeneration programme. The first approach in cell based techniques is the use of native progenitor cells.

Biomolecules

Besides an appropriate scaffold and cell source, signaling molecules represent an interesting tool in TE to modulate several aspects of cell biology from proliferation capacity to specific phenotypic features of fully differentiated cells. In the cellular milieu, the presence and gradient of soluble factors such as growth factor, chemokines, and cytokines play an important role in biological phenomena such as chemotaxis, morphogenesis and wound healing. In particular, these signals are tightly controlled and unique to each organ.

Market potential

Medical textile is one of the fastest growing sectors at 12 per cent per annum in technical textiles. It includes textile materials used in hygiene, health and personal care as well as surgical applications. Medical textile market in India is estimated to be Rs 47,700 crore and is expected to grow over 15 per cent for the last five years. India’s meditech segment is expected to grow at a rate of 20 per cent to $1,039 million by 2016-17, as per estimates of the Working Group on Textiles and Jute Industry, Ministry of Textiles, Government of India.

References

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Neha Junare is M Tech (Textile Technology Final Year) and B Tech (Textile Technology Gold Medalist). She is in Quality Assurance Department of Aarvee Denims and Exports Ltd.

Prem Viswanath is M Tech (Textile Technology), and General Manager – Quality Assurance Department at Aarvee Denims and Exports Ltd.