Synthesis of silver nanoparticles embedded on silica by gamma irradiation for utilization as antimicrobial agents

Silver nanoparticles deposited on silica (Ag nano/SiO2) have been prepared by Co-60 gamma irradiation of the mixture Ag+/SiO2/H2O/ethanol. The reduction of Ag+ in the suspension of SiO2 is brought by e-aq and H· generated during the radiolysis of water/ethanol solution. The presence of SiO2 prevents agglomeration of Ag clusters. The conversion dose (Ag+® Ag0) was determined by UV-Vis spectroscopy. Transmission electron microscopy (TEM) characterized the size of Ag nanoparticles. As a result, the particle sizes were determined to be in the range of 5-20 nm for an Ag+ concentration of 5 mM. The crystal structure of silver nanoparticles was also investigated by X-ray diffraction (XRD). In addition, the antifungal activity of Ag nano/SiO2 was tested against Aspergillus niger var Tieghn by plate count method. The results indicated that the antifungal efficiency of Ag nano/SiO2 was about 64, 71, 81, 82, and 96% at the concentrations of Ag nanoparticles of 30, 50, 70, 100, and 150 ppm, respectively.