The mechanistic actions of different silver species at the surfaces of polyacrylonitrile nanofibers regarding antibacterial activities

The mechanism of action and toxicity of silver species have been suggested by numerous direct observations. However, as far as we are concerned, comprehensive research to compare modes of action between different silver species at identical silver contents has not yet been reported. The activities of silver species at the interfaces of nanofiber scaffolds and bacterial medium under the impediment of chloride salt, present in antibacterial assays, are very complicated and could bring deeper understanding for research upon antibacterial applications using silver. Here, we prepared silver nitrate, silver zero-valent nanoparticles, and silver monovalent nanoparticles, incorporated in the nanofiber scaffolds at similar silver contents, then, compared all samples regarding antibacterial effects and fibroblast cytotoxicity. For confirming the success of fabrication, SEM, TEM, EDS, and FT-IR were implemented. Silver nanoparticles were observed to adhere on the nanofibers for Ag2O-PAN 1/20, Ag2O-PAN 1/5, Ag-PAN 1/20, and Ag-PAN 1/5 samples. The XRD spectra exhibited different sets of peaks for zerovalent and monovalent silver nanoparticles, which gave evidence about the nature of silver species incorporated in nanofibers. The XPS data gave an insight into the interactions between silver and the other molecules in the polymer matrix. The antibacterial evaluation gave the demonstration for theories about silver actions in the bacterial medium with the presence of halide anions, which sabotaged the antibacterial actions of silver nitrate and made it the least potent antibacterial agent among different silver species.