Enhanced antimicrobial activity of silver/polyrhodanine composite decorated silica nanoparticle

Abstract

This work describes the novel solution system synthesis of silver/polyrhodanine composite decorated silica NPs. Polymerization of polyrhodanine proceeded preferentially on the surface of the silica NPs where the Ag+ ion was located. During the polymerization, the embedded Ag+ ions reduced to metallic Ag NPs and consequentially silver/polyrhodanine composite NPs (ca. 7 nm) were formed on the surface of the silica nanoparticle. The existence of silver NPs and polyrhodanine on the silica NPs were verified through microscopic observation, FTIR, UV-vis, and XRS analysis. The composite nanoparticle decorated silica NPs exhibited excellent antimicrobial activities against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Importantly, the synthesized composite NPs retained antimicrobial activity under silver depletion condition due to the contact-active biocidal polyrhodanine. Therefore, it can be anticipated that the silver/polyrhodanine composite decorated silica NPs have potential for use as a long-term antimicrobial agent.