A fabric-based sheet material has been developed for water lining applications. Generally LDPE films of around 200 micrometers are used in India for lining in canals and water ponds, but these films get damaged during construction itself and hence serve very limited purpose in controlling water seepage. Internationally, HDPE sheets with thicknesses of 1.5-2.0 mm are used. However, as these are thick sheets, there is significant cost of transportation and installation. The sheets developed at IIT Delhi are of around 0.5 mm thickness with puncture and other properties comparable to that of the ones used internationally. These sheets are typically used in buried versions to protect from (a) stealing/vandalism and (b) direct sunrays to increase the life. These sheets support all type of protective layers like soil cover, stone pitching, brick layer or cement/concrete layer. These sheets are generically referred as geomembranes.

These sheets have been used successfully for water seepage control at several locations in the country. These locations are (i) a channel at Water Technology Centre, Indian Agriculture Research Institute (WTC,IARI) shown in Photographs 1&2; (ii) a pond at IIT Delhi shown in Photograph 3; (iii) several ponds at Central Agriculture Research Laboratory(CARI), Port Blair (photograph 4); (iv) a pond at Karjat, Maharashtra by an NGO Jalvardhini Pratishthan(jalvadhini.com) as shown in photograph 5 and also (v) a pond at Water Technology Centre Eastern Region (WTCER), Bhubaneshwar.

The results show that the water seepage is significantly controlled with these sheets. Thus, the sheets developed at IIT Delhi are useful for seepage control for a range of applications i.e. canal, tanks, dams and other water bodies. These could also be used in rehabilitation of existing canals, dams etc. These may prove most effective in expansive soils where concrete lining would result into cracks. The sheet materials could find applications in construction industry, specifically in basement and roof construction. Repair jobs for water seepage control could be plentiful.

The polymeric materials have generated considerable interest in human healthcare where materials in the form of films, and fibrous structures are being used. The biomaterials represent the most innovative domain of medical science & technology where these materials remain in close contact with the biological environment. The major requirement of the materials is the bioreceptivity and biocompatibility at the application site in human being. The Bioengineering Group in the Centre for Polymer Science & Engineering and, Department of Textile Technology at IIT Delhi has been working in four domains: Sutures, Wound dressings, Tissue Engineering and Nanobiotechnology.

Polymer Functionalization
Polymers are the backbone of biomedical technology. Quite often polymers do not have required features for their application in bio and medical fields. This is where the selective modification 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.

Development of materials by graft polymerization of monomers, such as acrylic acid, methacrylic acid and N-vinyl pyrrolidone onto polymer is an interesting route. 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. This material would release the drug whenever the fever rises beyond 37ºC. Plasma treatment of polymer surfaces is being used to carry out nanoscale changes on the surface. 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.

Sutures
The recent efforts have been directed more in the area of antimicrobial sutures. 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 polyester and polypropylene monofilaments is being pursued by graft modification of the sutures, since last eight years. 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. An antimicrobial drug is immobilized on the suture surface which is subsequently released into tissues surrounding the stitch and prevents the microbial invasion. The tissue compatibility of these sutures is excellent and no adverse reaction on mouse has been observed against these sutures.

Wound Dressings
The development of Wound care systems is another area of biomedical technology. The textile based dressings with bioactive components offer fast healing of the wound along with the minimization of the scar formation at the wound site. The wound dressing materials based on polyvinylalcohol/ polyethylene oxide (PVA/PEO) and Aloe vera are interesting so that the wound undergoes proper healing where scar formation is the minimum. Wound care dressings based on CS/OCMC coated cotton fabric also have been developed which have shown good exudates absorption, air permeability and required tensile strength. These dressings exhibit high porosity (~70%) and scar preventive nature. Drug is added to reduce pain. The incorporation of drugs into the above dressings makes them antimicrobial and helps in control of infection around the wound. These dressings will be useful to enormous people suffering from painful wounds.

Tissue Engineering
Tissue engineering has been defined as an interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function. Tissue engineering has been extremely innovative approach to deal with the human organ reconstruction. The approach has been to develop both the biostable and biodegradable textile scaffolds which have been subsequently transformed into a biodegradable matrix by plasma processing technology. The group has moved from biostable knittings to biodegradable knittings based on polylactic acid so that the composite structure of harvested cells and the scaffold may be transplanted to the damaged site in the bladder.

Efforts are specifically targeted towards the problems of Atherosclerosis and Aneurysm. This leads to hardening of plaque and resulted in narrowing arteries subsequent to angina. To overcome these problems, tissue engineering approach is followed for the regeneration of blood vessels using biostable as well as biodegradable polymers. The idea is to design biodegradable polycaprolactone based scaffolds and braidings of less than 6 mm diameter, followed by cell seeding on these scaffolds. Once the scaffold degrades out during the transplantation stage, it leaves behind the blood vessel as the original one.

Nanobiotechnology
Nanobiotechnology is the newest activity of biomedical science. 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 polymerization is assisted by gamma radiation and the reduction of silver proceeds during the polymerization stage.

The interest lies in the development of the functional nanogels which have 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. We have successfully prepared nanosilver nanohydrogel which is functionally active antimicrobial agent, which can be directly attached with the surface of catheter. The sizes of these nanoparticle are in 5 to 50 nm depending upon the polymerization conditions.

• Collaborators:
  
• Prof. J. Hilborn, University of Uppsala, Uppsala, Sweden
• Prof. Didier Letourneur, Hospital Bichat, Paris, France
• Prof Joelle Amedee, University of Bordeaux, France
• Prof. Alok Ray, IIT Delhi
• Prof. B.L. Deopura, IIT Delhi
• Prof. Arti Kapil, AIIMS, New Delhi
• Prof Anupama Sharma, Panjab University, Chandigarh, India
• Prof. S. Alam, Jamia Hamdard University, Delhi
• Prof. S. Bhan, NEHU, Shillong

• Scientific Staff:
• Sadia Anjum
• Tanushree Sen
• Roopali Agarwal
• Shamayita Patra
• Mythili Tummalapalli
• Surabhi Singh
• Sheetal Monga
• Jincy Joy
• Prashansha Dalal
• Shanti
• Pramod

• Financial Assistance:
• European Union
• INSERM, Paris, France
• Uppsala University, Sweden
• DBT, India
• CSIR, India
• ICMR, India
• IIT Delhi

Group has published 150 papers on research work that has been carried out in our laboratory. Around 240 papers have been presented in conferences, 24 patents have been filed and 8 books have been authored. A large number of conferences have been organized in the above given research domains. Also many research projects have been completed and going on in our laboratory.