Polymers are the backbone of biomedical technology. The polymers do not have required features for their application in bio and medical fields. This is where the selective modification of the biomaterial is needed. Following are the approaches for our ongoing functionalization technology towards the biomaterial development. The inherent vision of polymer functionalization is to introduce specific properties such as biocompatibility, bioreceptivity and biointeraction.
Radiation Grafting: The radiation grafting is one of the most interesting techniques where a monomer is polymerized onto the pre-existing polymer. As a result, a branched structure is formed. By virtue of the grafted branches, selective modification of the polymer is achieved while the inherent properties of the material are retained. We have been developing polymers by graft polymerization of monomers such as methacrylic acid and N-vinyl pyrrolidone onto polyester. The fabrication of a thermosensitive textile based on gamma ray induced graft copolymerization of acrylic acid and N-isopropyl acrylamide on polypropylene nonwoven fabric as a base material is being carried out, which will be used for transdermal drug delivery.
Schematic representation of the grafting process
Plasma Grafting: Plasma treatment of polymer surfaces is being used to carry out nanoscale changes on the surface. The surface chemistry is being modified by using different gases in such a way that desired functional groups are created. In a more advanced stage, the plasma activated surface is being grafted with different monomers so that a biocompatible and bioreceptive surface may be developed. The plasma activation is being used to develop materials for bioimmobilization and biocompatibility with the biological system.
Plasma Functionalized PP filament
The development of wound care systems is another area of the biotextile activities in the department. The aim of the present work is to develop wound dressings which are innovative in terms of the comfort and performance. The wound dressing activity has been going on in collaboration with Prof. M.S. Alam, Jamia Hamdard University at New Delhi. We have designed and developed wound dressing materials based on Polyvinylalcohol/ Polyethylene oxide (PVA/PEO) and herbal compounds so that the wound undergoes proper healing where scar formation is the minimum.
Antimicrobial Activity of Herbal Compound based dressing against E. Coli (ATCC11105), 1:106
Our recent efforts are to develop wound dressings based on pectin, gelatin hydrogels for enhanced wound healing. The incorporation of drugs into the dressings makes these dressings antimicrobial and help in control of infection around the wound. We have been able to produce a dressing which shows 98% scar prevention. Nanosoy reinforced dextran nanocomposite wound care membranes have been designed for scar free wound healing. Our subsequent studies are planned for the human trials very soon.
Scheme for the Modification of Pectin
We have also developed hydrogel wound care dressings based on Chitosan/PEG/PVP coated cotton fabric which have shown high porosity, good exudates absorption, air permeability and required tensile strength. Wound dressings composed of natural polymers chitosan and carboxymethyl cellulose have been developed. These blend membrane shows enhanced activities and provide an optimal environment condition for wound healing process.
The recent efforts in our lab have been directed more in the area of Suture materials. The development of an antimicrobial suture based on nylon polypropylene, polyethylene and polyester monofilaments is being pursued by graft modification or plasma functionalization of the sutures since last ten years.
The biomaterial activity is dedicated to the development of the Smart systems for drug delivery applications. We have been able to develop hydrogels by radiation induced copolymerization of various monomers with N-isopropyl acrylamide monomers into crosslinked structures. These materials offer excellent ability for the pH-sensitive or thermosensitive drug delivery in biological systems. The thermosensitive textile fabric has been developed which undergoes phase transition at 37.5ºC so that this patch can be used for the transdermal drug delivery systems.
Transdermal Drug Delivery Patch
Our group is working on the fabrication and characterization of a pH and temperature-sensitive textile for transdermal drug delivery, based on gamma ray induced graft copolymerization of acrylic acid/ N-isopropyl acrylamide on polypropylene nonwoven and polyester woven fabric as a base material. These patches undergo drug release at a temperature which is higher than 37°C leading to the smart drug delivery application.
Schematic representation of thermosensitive textile material
Recently, we are working new area of smart materials, we have been developed polyacrylic acid based self-healing hydrogels. Hydrogel shows efficient self-healing with in very short span of time with excellent tensile strength property.
Polyacrylic acid based self-healing hydrogels
The Tissue Engineering is the most fascinating domain where an alternative to the existing transplantation approach has been visualized. The medical textile group has made significant progress in the development of scaffolds for human urinary bladder reconstruction and cardio-vascular scaffolds collaboration with the Swedish group.
Nanobiotechnology is the newest activity of our group at IIT Delhi. We have been interested in the preparation of the nanohydrogels where nanosilver may be generated in-situ. The approach is to prepare w/o nanoemulsions where the hydrophilic monomer represents the water phase. The non-polar solvent acts as the oil phase. The polymerization is assisted by gamma radiation and the reduction of silver proceeds during the polymerization stage.
Nanosilver within nanogel structure and treated E. coli
Size-controlled preparation of soy protein isolate nanoparticles (nanosoy) has been done by using nanoprecipitation method. Excellent control over protein aggregation was achieved, producing nanoparticles in the size range of 5–15 nm.
TEM images of nanosoya protein particles
The interest lies in the development of the functional nanogel which has the tendency to interact with the biomaterials surfaces and make them antimicrobial. The nanosilver gels prepared in our laboratory exhibit a number of properties that have not been seen before.