Functionality, antibacterial efficiency and biocompatibility of nanosilver/chitosan/silk/phosphate scaffolds 1. Synthesis and optimization of nanosilver/chitosan matrices through gamma rays irradiation and their antibacterial activity

Silver nanoparticles (SN) were synthesized via the green approach of gamma radiation. Chitosan was used as both reducing and stabilizing agent. Studies involved the influence of various parameters of four irradiation doses and three silver precursor concentrations on the produced silver nanoparticles. The UV-vis spectra proved characteristic surface plasmon resonance (SPR) of SN whose intensities and positions were dependant on silver concentrations. X-ray diffraction analyses and transmission electron microscopy (TEM) observations proved the fabrication of spherical crystalline face centered cubic SN with a mean diameter of 7-22 nm. Further characterization of the fabricated silver nanoparticles/chitosan composite (SNCC) was conducted using Fourier transform infrared spectroscopy and zeta potential measurements. Finally, the bactericidal effect of the SNCC with glutaraldehyde was tested against three different medically relevant strains of gram negative and gram positive bacteria. Excellent selective inhibiting function of the films was proved by the gram positive strain compared to the other gram negative ones. The synthesis and successful size selection of SN obtained through gamma irradiation reduction of silver nitrate using chitosan as a protective agent was achieved presenting high bactericidal functions, especially for the gram positive strain.