• Biomaterial
• microgel
• nanotube
• Silk fibroin

The thesis is focused on preparation of Bioactive Polymeric Materials for Biomedical and Environmental Applications. In the first year of research activity, attention was posed on the isolation of lignin from renewable resources agricultural waste fiber and formulation of its blends with oxo-biodegradable low density polyethylene (LDPE). Blends were compatibilized with ethylene-vinylacetate copolymer and prodegradant responsible of oxo-biodegradation of relevant carbon backbone polymers. The low cost bio-based hybrid materials were formulated by following a statistical mixture design. The results attained in this first part of the thesis suggest that lignin may be used as a reinforcing agent, it turned out that polyethylene-lignin hybrid blends constitute an interesting way to produce low cost materials with fairly enhanced properties. Evaluations about components compatibility were characterized by ATR-FTIR, TGA, DSC, SEM, XRD, EDX, CHN and mechanical properties.
The second part of the thesis was based on the preparations of bioactive hybrid polymeric biomaterials consisting of poly (vinylalcohol) (PVA) and chitosan (CHI) and relevant composites loaded with multiwall carbon nanotubes (MWCNTs) and studied the effect of CNTs on the 3D scaffolds and 2D membranes. The use of CNTs in the field of tissue engineering represents a challenging but potentially rewarding opportunity to develop the next generation of engineered biomaterials. Hybrid materials loaded with MWCNTs were prepared and characterized morphological, thermal and de-swelling and phase transition and state of water inside of hybrid materials to explore the ability of the material to be a novel biomaterial. Hybrid novel materials loaded with CNTs retained the basic characters of synthetic polymer PVA and biopolymer chitosan, gelatin, ulvan and pristine CNTs. The effect of MWCNTs in the hybrid membranes was more significant when its amount was of 50 x 10-2 % w/v. The loading of water dispersed MWCNT in hybrid materials did not cause any appreciable cell citotoxicity as determined on the water extracts of the composite specimen. The presence of MWCNT up to 50 x 10-2 % w/v content in the investigated materials does not negatively affect the biocompatibility of the hybrid polymeric blends used as continuous matrix. The presence of even small percentage of MWCNT does not alter appreciably the overall structure of the blending materials, however beneficial effect on the overall continuous polymeric matrix reinforcement was observed. Carbon nanotubes based scaffolds and membranes can be ideal candidates and a good potential for the biomedical and pharmaceutical applications.
The last part of the thesis was carried out at HST-MIT division and Tufts University. The synthesis of four different types of novel glyco dendrimer and explored its conjugation with anti cancer drug Taxol at HST-MIT divission. The results obtained were not so significant and will be carried out in future study. Further the research was carried out under the dynamic supervision of Prof. David Kaplan at Tufts University on the preparation of silk based biomaterial. The use of silk fibroin (SF) in the field of tissue engineering represents a well known biomaterial and potentially rewarding opportunity to develop the next generation of engineered biomaterials. In this context the research on the study of sol-gel transition behaviour upon the exposure of ultrasound, molecular weight reduction by ultrasound effect, ultrasound induced silk/biopolymer gelation, and preparation of microgel by proteolytic enzyme α-chymotrypsin and silk fibroin conducting hydrogel with poly aniline and poly pyrrole. The research explains the sol-gel properties of different concentration of SF, ATR-IR, TGA, DSC, state of water, XRD, EDX, CHN and morphology of SF based biomaterial and other properties to explore the ability of the material to be a novel biomaterial. The ease preparation and potential to engineer their physicochemical and bioactive characteristics makes these sonication induced methods true alternatives for SF as new platforms. The observed effects of sonication will offer new opportunities to use ultrasound in the formation of SF gel, induced SF/biopolymer gel, micro and nanogel by controlling the beta sheet. The effect of ultrasound on SF molecular weight is also a new approach. The novel SF microgel was prepared by proteolytic enzyme and conducting SF scaffolds were prepared by insitupolymerization of pyrrole and aniline by using oxidant. This provides a novel approach to solve tissue engineering problem.
The present and previous work in our laboratory encourages for further detail study on the preparation of the different biopolymer biomaterials for tissue engineering applications.