Recent Development in Medical Textile

An important field of application of textile in medicine has been developed such as wound care and preventing chronic wounds. Bandages and wound dressings are most commonly used because they are affordable and reusable. The medical textile should have bio-compatibility, flexibility and strength. In surgical dressings the “sorbagon” dressings are innovated to produce more comfort in the dressing of wounds.

Some of the superabsorbent polymers are innovated, which includes polyacrylate and sodium acrylate are made to improve the absorbency of the fibres. The recently developed calcium alginate. The extracorporeal devices such as artificial kidney, mechanical lung, and artificial liver have been modified.

(Read)Textile Fibres & Classification Fibres
Fibres have the high super absorbing capacity. Recent advances and specific requirements necessitated innovation in surgical sutures which include barbed sutures. The textile materials have generated considerable interest in medical technology where materials in the form of monofilament, multifilament, woven and nonwovens 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 the human being.

Introduction

(Read) Medical Textile – Classification & Applications

The term medical textile literally means textile used for medical purposes. Textile apart from being a vital part human life is long since been used in medical field, though the term has been coined very recently. Textile materials have wide range properties such as flexibility, elasticity, strength etc.

Textiles used for medical purposes should be non-allergic, non-carcinogenic, non-toxic, and antistatic in nature, optimum fatigue endurance, bio-compatibility, flameproof, dyes must be the nonirritant. An important and growing part of the textile industry is the medical and related healthcare and hygiene sectors.

The extent of the growth is due to the constant improvements and innovations in both textile technology and medical procedures. They are used in a number of separate and specialized applications which can be categorized as follows:

• Non-implantable materials: Wound dressing, bandages, plasters etc.
• Extracorporeal devices: Artificial kidney, liver, and lungs.
• Implantable materials: Sutures, vascular grafts, artificial joints etc.
• Healthcare/hygiene products: Bedding, clothing, surgical gowns cloths, wipes.

Recent Developments in Medical Textiles

Artificial kidney

The kidneys serve as filtering devices of the blood. The nephrons, the working units of the kidney, filter waste materials out of the blood and produce urine to secrete toxins from the body. The kidneys also maintain normal concentrations of body fluids, which play a key role in homeostasis. In the natural kidney, ultrafiltration of the blood occurs through the glomerular capillaries leading to the removal of waste products and the purification of blood.

In an artificial unit, a membrane-dependent-ultrafiltration achieves essentially the same result. hemodialysis is indispensable for people suffering from kidney disease.

The function of the artificial kidney is achieved by circulating the blood through a membrane, which may be either a flat sheet or a bundle of hollow regenerated cellulose fibres in the form of cellophane that retain the unwanted waste materials.

Multilayer fibres composed of numerous layers of needle-punched fabrics with varying densities may also be used and are designed to remove the waste materials rapidly and efficiently. The synthetic polymer substitute being experimented with is a polyethylene glycol-polyethylene terephthalate block copolymer membrane which can selectively filter.

The material used in dialysis membranes are regenerated cellulose, cellulose triacetate, acrylonitrile copolymer, poly (methyl methacrylate), ethylene-vinyl alcohol copolymer, polysulfone and polyamide which can be grouped as cellulose and synthetic polymer systems.

Eighty per cent of the dialysers uses cellulose materials which have excellent permeability for low molecular substances. Pore sizes of membranes vary between 1 – 3 nm for conventional membranes and 4 – 8 nm for large pore membranes.

Today, high efficient hollow fibres have replaced coil or laminate in dialyzer devices. The cross-section of a hollow fibre type dialyser is shown in Figure 3, which consists of 4,000 to 20,000 hollow filaments having an external diameter of 200 to 300 micrometer.

Blood flows inside of the fibres and the dialysate flows outside of the fibres. Almost the same materials are used for hemofiltration. The term ‘Artificial kidney’ is often applied to the whole system including the pumps and control circuitry for the dialysate mixing and delivery, and for the blood preparation and monitoring, pumping, deaerating and return to the body.

The development of artificial kidneys depends on the development of hollow fibre membrane. The polymer can be spun into hollow fibre membrane as shown in Figure 4. The artificial dialysis membrane is the most advanced fibre in the medical industry.

Artificial kidney dialysis is accepted as reliable. The purpose of the development of artificial kidney dialysis membrane is to mimic the ability of the kidney to completely remove wastes like urea and albumin. One of the side effects of long-term dialysis is a shoulder injury caused by ß2-microalbumin accumulating so that the joint cannot move. Big pores are effective in removing waste.

However, other necessary components are also removed. The problem can be solved by making a monomolecular layer fibre, which is controlled by the relation of surface structure to waste blood. There remain problems to be solved in controlling of material and holes on the surface of the hollow fibre.

To improve dialysis membrane development, it is necessary to make fibre more identical to the organ itself. At present, heparin is used to prevent clotting of blood. If the patient who undergoes dialysis is a diabetic, the amount of heparin used must be decreased. Therefore, biocompatibility of the material needs to be achieved.

An external artificial kidney, a hemodialyzer, is used which can perform many of the functions of a kidney. It is attached to the blood circulation via, an artery and a vein. Since the dialyzer is a foreign substance to the human body, when the blood is circulated through the dialyzer, the leucocyte count in the blood decreases over the first 20 minutes of dialysis but recovers to its original value after 1 hour.

It is made up from a bundle of hollow fibres through which the blood circulates. The objective is to improve the surface of hollow fibres so that the leucocyte decrease does not occur. Kidney troubles, it is believed, can be caused by proteins of molecular weight in between 10,000 to 30,000.

The blood also contains substances that must be retained, such as albumin with a molecular weight of about 70,000. Each hollow fibre manufacturer is now developing a suitable membrane, through which the harmful proteins of molecular weight around 20,000 passes but not the proteins of the molecular weight around 70,000. These could have many practical benefits.

Mechanical lung

Mechanical lungs use microporous membranes that provide high permeability for gasses (both O2 and CO2) but low permeability for liquid flow and functions in the same manner as the natural lung allowing oxygen to come into contact with the patient’s blood.

During the flow, oxygen, which is maintained at a high partial pressure, displaces carbon dioxide, thus effecting purification. In this devices, oxygen flows around hollow fibres at extremely low pressure. Blood flow inside of the fibre.

The oxygen permeates the micropores of the fibre and comes in contact with the blood. The pressure gradient between the blood and oxygen is kept near zero to prevent mixing of oxygen and blood. Red blood cells capture oxygen by the diffusion process.

The mechanical lung was first developed as a device to replace lung function during heart surgery and is now extensively used for this purpose in the USA (about 250,000 per year) and Japan (20,000 per year). A newer form of the artificial lung can also be used as a supplementary respiratory device over a longer term to assist the breathing of patients suffering from acute lung or heart failure, or older people with weak lung function.

Silicone or polypropylene hollow fibres are used for the fabrication of the mechanical lung to allow permeation of gasses. It ideally should function for at least 1 to 3 weeks. But the present mechanical lung can function only for a week, because, its ability to remove carbon dioxide falls off.

The lung is a form of the gas exchanger to supply oxygen to the blood and remove carbon dioxide. The best membrane material available and in extensive use is silicone, which not only has a high permeability to gasses and low permeability to water but can also be autoclaved.

Mitsubishi Rayon Co (Japan) has developed a microporous polypropylene hollow fibre for the manufacture of an artificial lung and is currently supplying the fibre to medical device manufacturers. Here gasses freely pass through the pores of PP hollow fibres, but not the blood, because of the hydrophobicity of PP membrane.

As a result, the artificial lung of the gas-bubble type is rapidly being replaced with the membrane type. PP hollow fibre exhibits good compatibility with blood and excellent gas permeability. Its use allows the design of a compact artificial lung that is easy and safe to operate.

However, its long-term use causes a leak of blood plasma components, and an investigation is underway to improve the membrane material in order to eliminate this disadvantage. The progress in developing an artificial lung has been slow due to difficulties in engineering problems and limitation of required materials.

Artificial liver

The artificial liver utilizes hollow fibres or membranes similar to those used for the artificial kidney to perform their function. Organ cells are placed around the fibres and blood flows inside the fibre. Blood nutrients pass through the fibre wall to the oxygen cells and enzymes pass from the cells to the blood.

The metabolism of the liver is very complicated which poses problems for the artificial liver. This can be solved by using a double lumen structure with a hollow fibre within a hollow fibre. Blood runs outside and in contact with liver cells and blood, and after purification it runs inside the fibre.

The liver is a remarkable organ; Like the skin, it can regenerate after severe trauma. In fact, a patient can recover with only 20% of his or her liver still functional, as the liver grows back. However, there is a point of ‘No return’ after which the liver cannot regenerate, and there are underlying disease conditions that, in some cases, make a transplant the only alternative.

Unlike the heart, lung or kidneys, which have one primary function, the liver has multiple functions essential to maintain life including carbohydrate metabolism, synthesis of proteins, amino acid metabolism, urea synthesis, lipid metabolism, drug biotransformation and waste removal. Therefore the preferred artificial liver support system would perform these various liver functions.

Hepatocytes carry out many vital biological functions, such as synthesis and catabolic reactions, detoxification and excretion. Due to their ability to restore a tissue-like environment, hollow fibre bioreactors (HFBs) show great potential among different systems used to culture hepatocytes.

Currently, the major use of Hepatocyte Hollow Fibre Bioreactors is as bioartificial livers to sustain patients suffering from acute liver failure, but they can also be used to synthesize cell products and as cellular models for drug metabolism and transport studies.

The artificial liver utilizes the functions of separating, disposing of & supply of fresh plasma in hollow viscose fibres or membranes similar to those used for the artificial kidney to perform their function. In the case of extracorporeal devices, cells are grown to confluence in devices resembling dialysis cartridges and then inserted into a ‘Circuit’ outside the patient’s body, where blood from the patient flows through the cartridge, contacting the cells, and then back into the patient.

Extracorporeal liver assist device (ELAD) or bioartificial liver (BAL). The principal goal of the ELAD is to circulate a patient’s plasma extracorporeally through a bioreactor that contains metabolically active hepatocytes.

Such devices are expected to increase the life of the patient, improve the care and quality of life of patients and to reduce care costs. ELAD cartridge is a hollow fibre dialysis cartridge that contains a semi-permeable membrane with a low molecular weight cut-off.

This allows for the physical separation of the cells from certain, but not all, components found in the patient’s blood, as well as permitting the cells to secrete vital molecules back into the patient. Membranes used in BAL: Cellulose acetate, Cuprophan, Hemophan, Polyamide, Polypropylene, Polysulfone.

Surgical Sutures 

Fibres 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 a human being.

A lot of work has been done 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.

Barbed sutures

Recently a bi-directional barbed suture has been developed which obviates the necessity to tie a knot. It has the ability to put tension in the tissues with less suture slippage in the wound, as well as to more evenly distribute the holding forces thereby reducing tissue distortion.

The barbed suture with a steeper cut angle and a median cut depth have a higher tissue holding capacity than those with a moderate cut angle and a nominal cut depth.

DRESSING MATERIALS:

Calcium Alginate Fibres 

The raw material for the production of this fibre is alginic acid, a compound obtained from the marine brown algae. It possesses 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, This fibre is placed on the wound in a dry state and begin to absorb the exudates. The calcium ions are then gradually exchanged against sodium ions that are present in the blood and wound exudates.

The fibre 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.

The 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 may 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 a 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 provided 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.

Germs and detritus are retained within the gel structure as the fibre swell during subsequent gelatinization. The wound is thus effectively cleansed and a considerable reduction of the microorganism can be attained.

Intra capillary absorption of exudates along with swelling and gelatinization however not affect the fundamental permeability of the dressing for moisture. The gel remains permeable to gas so that sorbalgon represents a dressing material that facilitates a permeable moist wound treatment, in contrast to an occlusive moist wound treatment with hydrocolloids.

This especially important in infected wounds where air penetration reduces the risk of dangerous infection with anaerobic bacteria.

It is not a woven, rather consist of supple, fibrous mat that has excellent shaping and packing capabilities. When the fibres swell during gelatinization and finally fill out the wound, a close contact to the wound is generated even in the almost inaccessible areas, absorption of wounds exudates thus being ensured even at the deepest point of the wound.

Despite it high absorption capacities it prevents the wound from drying out without difficulties. The gel-like consistency of sorbalgon acts as a moist dressing during the whole therapy and helps to regulate physiological secretion. This creates a favorable micro climate for wound healing promoting granulation and epithelialisation.

Super Absorbable Polymer

Superabsorbents are swellable cross-linked polymer, which has the ability to absorb and store 400-600 times their 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 meltable 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 the 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.

Chemical structures of some of these materials are illustrated in Figure 3.1.

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., polyglycine). 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.

Water-absorbent Polymer

Water absorbent polymers are known as hydrogel, 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 hydrocarbon chains.These bridges are known as

These bridges are known as cross-linking, which enables the polymer to form a huge single supermolecule, including its ability to degrade in the environment and breakdown into simpler molecules and hold the significant amount of water. When water comes in contact with super absorbent and electrical repulsion takes within 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.

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.

These bridges are known as cross-linking, which enables the polymer to form a huge single supermolecule, including its ability to degrade in the environment and breakdown into simpler molecules and hold the significant amount of water. When water comes in contact with super absorbent and electrical repulsion takes within 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.

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.

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.

Antimicrobial Textile

Antibacterial fibre 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 whites, which have protracted antimicrobial effect. The wipes are impregnated with biocides by spraying, dipping or soaking for use in medical field.

The great advantage of this material is that those are not to react with tissue. Flexible products such as sponges and textile whites, which have protracted antimicrobial effect. The wipes are impregnated with biocides by spraying, dipping or soaking for use in medical field.

Flexible products such as sponges and textile whites, which have protracted antimicrobial effect. The wipes are impregnated with biocides by spraying, 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 monocrystalline 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 the variety of wounds including graft and donor sites and surgical wounds.

Acticoat has the faster kill rate and was effective against more fungal species. The product can be applied to the variety of wounds including graft and donor sites and surgical wounds.

Antimicrobial Wound Dressing

Kerlix AMD is pure cotton treated with media’s poly hexamethylene brigandine agent. These antimicrobial agents resist bacterial growth within 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 a mixture of hydrophobic fibres and fibre comprising antimicrobial property.

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 thereby enhancing

The regulation of the blood flow and prevention of swelling is closely interlinked with this property and thereby enhancing improved healing process. It provides necessary support to restrict movement and speeds up the healing process.

The regulation of the blood flow and prevention of swelling is closely interlinked with this property and thereby enhancing improved healing process. It provides necessary support to restrict movement and speeds up the healing process.

(Read)Manufacturing Of Crepe Bandage With Bamboo, Tencel & Lycra Yarns

Textile Performance Principles

Textile materials for medical applications typically have specific performance requirements relating to strength, stiffness, abrasion resistance, and mechanical Patency.

Strength: Among the many factors affecting a fabric’s strength (fiber type, molecular orientation, crystallinity) is the variability in properties especially elongation of its constituent elements. Usually, the greater the variability in elongation at break, the lesser the strength. Products requiring high strength (e.g., artificial ligaments) must incorporate elements whose properties range within a narrow limit.

Stiffness: Bending stiffness which governs the handling, comfort, and conformability of a fabric is a critical parameter in a number of medical applications. A low value is usually desirable. For example, a suture with low bending stiffness requires fewer throws to tie a secure knot and has higher knot strength.

The most important factors affecting bending stiffness are the shape of the fiber and the modulus, linear density, and specific gravity of the material. Generally, the higher the denier or the modulus or the lower the specific gravity, the higher the bending stiffness.

For example, polyester has a higher modulus than that of nylon and will result in a stiffer material.Polypropylene, with a lower density than nylon, should have a higher stiffness, assuming all other factors are equal. In addition, a tribal or tubular structure produces a stiffer product than does a solid circular structure of the same area or linear density. Monofilament materials are much stiffer than multifilament.

With all other factors constant, the bending stiffness of a monofilament product such as a suture of denier T will be roughly n times greater than a multifilament structure with n filaments of denier T/n each. The use of multifilament yarns and/or fine-denier fibers in the yarn produces a more flexible and supple end product.

Knot efficiency the ratio of the tensile strength of knotted to the unknotted thread is affected by elongation at break and bending stiffness. Most often, the greater the elongation, or the lower the stiffness, the greater the knot efficiency.

Abrasion Resistance: Whenever fibers, yarns, or fabrics rub against themselves or other structures, abrasion resistance assumes an important role. A high value is usually desirable, especially in applications such as artificial ligaments or tendons. The abrasion resistance of a yarn is influenced by several factors:

• The denier of the fiber (the lower the denier, the lower the resistance).
• The amount of twist in the yarn that binds the fibers together (the lower the twist, the lower the resistance).
• The orientation of molecules in the fibers (the higher the orientation, usually the lower the resistance).The surface coefficient of friction (the higher the coefficient, the lower the resistance).Therefore, one can conclude that micro denier fibers, low-twist yarns, rough surfaces, and highly oriented materials generally exhibit low abrasion resistance. However, coating a bundle of fibers with a low-friction polymer can enhance its resistance to abrasion.

Mechanical Patency: Implanted products that must bear loads over the long term and maintain their dimensional integrity require a high degree of mechanical Patency that is, the ability to resist permanent change in physical size, shape, structure, and properties. The factors that contribute to mechanical Patency include:

• The chemical, biological, and stress environment into which the implant is placed.
• The nonreactivity of the polymer with the environment.
• The size of the fibers.
• The structure of the fabric (consolidated structures made of the highly interlocked woven material or warp knits provide an advantage).
• Perhaps most importantly, the viscoelastic properties of the material.

Thus, material selection is extremely critical for products such as ligament prostheses that must continue to bear loads. The material specified must be able to resist the elongation or growth that may occur as a result of stress relaxation during each cycle of operation in the body.

If no such material is available, then biological tissues will need to be integrated into the assemblage to provide partial support of the load and contribute to the product’s long-term Patency.

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 extracorporal 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 the 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.

REFERENCES

1. Development of Antimicrobial Suture by Radiation-induced Graft polymerization of acrylonitrile into Polypropylene Monofilament I. Influence of Synthesis Conditions.B. Gupta, R. Jain, N. Anjum and H. Singh j In Pres (2004)

2. Development of Antimicrobial Suture by Radiation-induced graft polymerization of acrylonitrile into Polypropylene Monofilament II. Characterization and Structural Investigations. B. Gupta, R. Jain, N. Anjum and H. Singh J. Appl. Polym. Sci., In Press (2004)

3. Plasma Induced Graft Polymerization of Acrylic acid onto PET Films: Characterization and Human Smooth Muscle Cell Seeding. B. Gupta, C. Plummer, J. Hilborn, I. Bisson and P. Frey. Biomaterials, 23, 863 (2002)