Bactericidal mechanisms of Ag_2O/TNBs under both dark and light conditions

摘要

Ag_2O/TNBs were fabricated by depositing Ag_2O nanoparticles on the surface of TiO_2 nanobelts (TNBs). The disinfection activities of Ag_2O/TNBs on two representative bacterial types: Gram-negative Escherichia coli ATCC15597 and Gram-positive Bacillus subtilis, were examined under both dark and visible light conditions. Ag_2O/TNBs exhibited stronger bactericidal activities than Ag_2O nanoparticles and TNBs under both dark and light conditions. For both cell types, disinfection effects of Ag_2O/TNBs were greater under light conditions relative to those under dark conditions. The bactericidal mechanisms of Ag_2O/TNBs under both dark and light conditions were explored. Ag+ ions released from Ag_2O/TNBs did not contribute to the bactericidal activity of Ag_2O/TNBs under dark conditions, whereas the released Ag+ ions showed bactericidal activity under visible light irradiation conditions. Active species (H_2O_2, O_2, and e ) generated by Ag_2O/TNBs played important roles in the disinfection processes under both dark and visible light irradiation conditions. Without the presence of active species, the direct contact of Ag_2O/TNBs with bacterial cells had no bactericidal effect.