Enhanced antibacterial activity and mechanism studies of Ag/Bi2O3 nanocomposites

In this work, sphere-like Ag/Bi 2 O 3 nanocomposites with the average size of ca. 170 nm were successfully synthesized by simple deposition-precipitation method. The antibacterial activities of as-prepared Ag/Bi 2 O 3 nanocomposites were evaluated by minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and colony counting methods. It was found that Ag/Bi 2 O 3 nanocomposites displayed greatly improved antibacterial ability against common pathogenic Gram-positive and Gram-negative bacteria in comparison with single-component Bi 2 O 3 nanospheres. More importantly, Ag/Bi 2 O 3 nanocomposites exhibited remarkably outstanding antibacterial activities against clinical drug-resistant bacteria. The antibacterial activity of Ag/Bi 2 O 3 nanocomposite increased with the increase of Ag content and 15 wt% Ag/Bi 2 O 3 nanocomposites showed the highest antibacterial activity. Furthermore, a plausible antibacterial mechanism of Ag/Bi 2 O 3 nanocomposite was proposed. It was believed that the enhanced generation of H 2 O 2 could lead to the membrane leakage of cytosol and the inactivation of respiratory chain dehydrogenaes, which was possibly responsible for the enhanced antibacterial activities of nanocomposites.