Preparation of Antibacterial Chitosan based Cryogel / Silver Nanoparticles Composites

In this thesis, four different types of cryogels were synthesized by using different concentrations of glutaraldehyde cross-linker and silver nitrate. Cryogel containing the highest concentration of cross-linker resulted in the formation of non-homogeneous cryogel structure due to localized viscosity increase around cross-linking agent. In other cryogels where cross-linker concentration was kept at 1% homogeneous mixture was achieved easily. Reduction of silver nitrate into silver nanoparticles was confirmed due to the observation of colour change from yellow to brown. Cryogel which contains no amount of silver nitrate did not go under any colour change. Drying and water retention capacity evaluation of cryogels showed that concentrated cross-linker containing cryogel had the highest water retention capacity wheras cryogel without any silver nitrate had the lowest water retention capacity. Antibacterial activity of cryogels were tested by evaluation of inhibition zone against E. coli and S. aureus. Maximum inhibition zone of 16 mm in E. coli and 15 mm in S. aureus was observed by the cryogel containing the highest concentration of silver nitrate. Keywords: Chitosan, Glutaraldehyde, Silver Nanoparticle, Antibacterial, Inhibition, E. coli, S. aureus