Synthesis and antimicrobial effects of colloidal silver nanoparticles in chitosan by<i>γ</i>-irradiation

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+ into Ag0) 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+ 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 (ED50) of inhibition for Corticium salmonicolor was of 27.2 ppm.