خواص ضد میکروبی فیلم های نانوکامپوزیتی نقره ای کیتوزان Preparation, Characterization, and Antimicrobial Properties of Chitosan–Silver Nanocomposites Films Against Fish Pathogenic Bacteria and Fungi

Introduction Development of nanostructured films with combination of natural polymers and metals has become an important research field of nanotechnology. Nano films can be applied in various aspects in aquaculture such as in water treatments and filtration, diseases control (as antimicrobial materials), reduce heavy metal toxicity, antifouling in aquaculture nets, and biodegradable packaging materials for seafood products [1]. The use of biopolymers for developing nano films has been increased over the past years due to their low cost, renewability, nontoxic properties and environment friendly processing methods. Among various biopolymers, polysaccharides such as starch, alginate and chitosan have been proven to be good materials [2–5]. Chitosan is a natural poly cationic linear polysaccharide composed of randomly distributed beta-(1,4)-linked Dglucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). In general, chitosan can be produced by deacetylation of chitin, which is a structural element in crustacean exoskeleton, insect cuticle and fungal cell wall. Chitosan has been widely used for developing nano materials due to excellent properties such as biodegradability and biocompatibility [2]. Besides that, chitosan has shown a wide array of antimicrobial activities and filmogenic properties. On the other hand, nano scale silver (Ag) or silver nano particles (AgNPs) have shown strong therapeutic power, hence, those materials have been applied extensively on various biomedical applications including antimicrobial and wound dressings [6, 7]. Moreover, the use of chitosan polymers as templates and reducing agents is considered as one of the effective alternatives to synthesize AgNPs [8]. Previous reports have dealt with biopolymers like chitosan [9], heparin [10] and soluble starch [11] as reducing and stabilizing agents for preparation of AgNPs. Anastas and Williamson [12] have emphasized that nano products should be developed by green synthesis methods to reduce the formation of hazardous waste.