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Monodispersed Ag/ core/shell nanoparticles were synthesized in solution via colloid-seeded deposition process using Ag nanoparticles as colloid seeds and as Ti-source respectively. Silver nitrate was reduced to Ag nanoparticles with in the presence of CTAB as stabilizing agent. The titania sols hydrolyzed by the solution deposited on the surface of Ag nanoparticles to form the Ag/ core/shell nanoparticles. Inductively coupled plasma atomic emission spectrometry (ICP-AES) showed low amount of Ag ion leaching from the Ag/ core/shell nanoparticles. The Ag/ core/shell nanoparticles indicated excellent antibacterial effects against Escherichia coli and maintained long-term antibacterial property.

could enterporous CS nanoparticles synthesized with this method, allowing Ag nanoparticles within chitosannanoparticles were synthesized by reducing silver nitrate with chitosan. Because of the noncovalent interactionbetween CS and EDTA, the EDTA could be easily removed via dialysis against water, and pure core/shell-typeAg/CS nanoparticles could be obtained. The nanoparticles showed higher antibacterial activity toward E. colithan the active precursor Ag nanoparticles and CS.Key Words : Chitosan, Nanocomposite, Antibacterial activityIntroductionChitosan (CS), obtained by extensive deacetylation ofchitin isolated from crustacean shell, is a natural polysac-charide with many useful features such as biocompatibility,biodegradability and antibacterial properties. It, as well as itsderivatives, has great potential applications in such areas asbiotechnology, biomedicine, and food technology.