Fabrication of new chitosan-based composite sponge containing silver nanoparticles and its antibacterial properties for wound dressing.

The purpose of this research was to investigate chitosan-based composite sponge containing silver nanoparticles (Ag NPs) for wound dressing application. The composite sponge was prepared by a freeze-drying technique, and then immersed in AgNO3 solution with different concentration and autoclaved at 15 psi, 121 degrees C for 15 min for the formation of Ag NPs. The composite sponge containing Ag NPs was characterized by UV-vis spectra, XRD and SEM. The characteristic peaks of Ag in the UV-vis spectra and the XRD pattern revealed the formation of Ag-NPs. The SEM image showed that the silver particles homogeneously distributed on the surface of the composite sponge with an average particle diameter of about 60-80 nm. The contents of silver determined by ICP Single-channel scanning spectrometer were 0.032, 0.096 and 0.166 weight percentage, respectively, when the composite sponge was correspondingly treated with AgNO3 at concentrations of 0.1, 0.25 and 0.5 mM. The results of enzymic degradation in vitro indicated that the Ag-NPs could obviously promote the degradation of the composite sponge. The bacteriostatic and bactericidal properties of the new sponge were preliminarily studied in vitro by using S. aureus E. coli and P. aeruginosa as test microorganisms. The test results demonstrated that the new Ag NPs-loaded chitosan-based composite sponge possessed not only bacteriostatic, but also bactericidal activity against these test bacteria.