Amphiphilic chitosan-graft-poly(epsilon-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by H-1 NMR, FIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coil and Staphylococcus aureus as model Gram-negative and positive bacteria. (C) 2014 Elsevier B.V. All rights reserved.