الفهرس 
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Abstract
Chitosan is derivative of chitin, which, considered as the second most abundant natural polysaccharide on the planet. Due to its properties such as antimicrobial activity, biocompatibility, non-toxicity, Chitosan has a wide range of applications especially, biomedical applications. In this study, Chitosan was prepared in two forms, general molecular form and nano form. High-quality Chitosan of low molecular weight and high degree of deacetylation had been extracted from Shrimp Shells The Parameters were Fixed at pH 4 and CS: TPP (Chitosan: tripolyphosphate) ratio was kept at 3: 1 to prepare Chitosan nanoparticles with 25.37nm size and 27.8mV charge density. The Chitosan nanoparticles were used as a host material for synthesis of metallic nanoparticles (gold and silver) to form photo-stable bio-nanocomposites. This bionanocomposite was designed to improve the antibacterial activity for both Chitosan nanoparticles and metallic nanoparticles which can be used safely in several antibacterial applications. The results revealed that the antibacterial activities were increased in the following order Chitosan-silver nanocomposite > Chitosan nanoparticles> Chitosan-gold nanocomposite >molecular Chitosan. The results also indicated that Chitosan-silver nanocomposite has a strong antimicrobial effect even for drug resistive bacteria such as S. aureus. The photostability study showed that Chitosan – metallic nanocomposites (i.e AgNP & AuNPs) are very stable against UV, Visible light and their shelve lifetime is more than 3 months for both Chitosan-gold bionanocomposite and Chitosan-silver bionanocomposite.