Radiation-induced synthesis of colloidal silver nanoparticles (Ag-NPs) using chitosan (CTS) as a stabiliser and free radical scavenger is feasible and satisfiable to green method. The conversion dose (Ag þ into Ag 0) was determined by UV-Vis spectroscopy and Ag-NPs size was characterised by transmission electron microscopy. The average diameter of Ag-NPs was smaller than 10 nm with narrow size distribution and the colloidal Ag-NPs have good stability for a long time of storage. The effect of several parameters, such as pH, Ag þ and CTS concentration and molecular weight of CTS on Ag-NPs size was also investigated. Ag-NPs of $7 nm exhibited highly antimicrobial effect. The inhibitory efficiency of Ag-NPs for Staphylococcus aureus was more than 99.9% at 5 ppm and the effective dose (ED 50) of inhibition for Corticium salmonicolor was of 27.2 ppm.

Colloidal silver nanoparticles were prepared by -irradiating Ag þ in aqueous solution in the presence of 2% polyvinyl pyrrolidone (PVP) as stabilising agent and ethyl alcohol as free radical (OH . ) scavenger. The saturated conversion dose of Ag þ into Ag was determined by UV-Vis spectroscopy and the silver nanoparticles size was characterised by transmission electron microscopy. The influence of Ag þ concentration (1-50 mM) on the saturated conversion dose and average diameter of silver nanoparticles was investigated. Results showed that the saturated conversion dose was from 8 to 48 kGy and the silver particles size was in the range of 6-21 nm for Ag þ concentration from 1 to 50 mM. The effect of PVP molecular weight on silver particles size was studied as well.

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