The synthesis of silver-nanoparticle-anchored electrospun polyacrylonitrile nanofibers and a comparison with as-spun silver/polyacrylonitrile nanocomposite membranes upon antibacterial activity

The preparation of as-spun silver–polyacrylonitrile composite nanofibers (Ag/PAN Com) and the in situ synthesis of silver nanoparticles anchored on the surface of PAN nanofibers were presented. The former were directly electrospun from the solution of PAN and silver nitrate (AgNO₃). The latter (AgNPs/PAN) were prepared by immersing as-spun PAN nanofibers in AgNO₃ aqueous solutions with different concentrations under the radiation of UV light, as a facilitator for the reduction of Ag ions into AgNPs. A comparison between these materials, which are based on silver and polyacrylonitrile but via two different synthetic methods, as antibacterial composite nanofiber membranes against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), was made. The success of synthesizing was confirmed by scanning electron microscopy and transmission electron microscopy (TEM). Chemical groups on the surfaces of nanofibers were detected by Fourier transform infrared spectroscopy. The crystallinity of PAN nanofibers, the crystalline alterations of Ag/PAN Com due to the penetration of silver ions into the polymer matrix of nanofibers, and the structural models of newly formed silver nanoparticles were ascertained by x-ray diffraction (XRD). The gradual transformation of Ag ions into AgNPs, which occurred near the surfaces of Ag/PAN Com nanofibers without any catalyst agents, was observed by TEM. The occurrence was also clarified by analyzing FTIR and XRD spectra. The inhibition zones of Ag/PAN Com membranes at the first cycle of bactericidal test appeared the most expansive against both strains of bacteria even with lowering the release amount of silver. However, the AgNPs/PAN exhibited a more sustainable antibacterial ability after the second and the third incubation cycles.