Synergistic enhancement in antibacterial activity of core/shell/shell SiO₂/ZnO/Ag₃PO₄ nanoparticles

Abstract

Novel core/shell/shell SiO2/ZnO/Ag3PO4 nanoparticles (SZA‐NPs) were prepared through a facile reflux method involving sequential deposition of ZnO and Ag3PO4 to SiO2 spheres. The obtained SZA‐NPs were systematically characterized and used as the dual‐functional antibacterial agents for disinfection. Under visible‐light irradiation, the SZA‐NPs exhibit enhanced antibacterial activity for of Escherichia coli DH5α (E. coli) compared to that of Ag3PO4 or SiO2/ZnO in liquid phase and on agar plates. Quantitative analysis of Ag+ release from SZA‐NPs confirms the minor contribution of released silver ions to the antibacterial efficiency. On the other hand, chemical scavengers and photoluminescence studies suggest that radical oxygen species (ROS) also make major contribution to E. coli cell death. The enhanced antibacterial activity of the SZA‐NPs under visible‐light irradiation can be attributed to the synergistic effect of released silver ions and ROS generated from the excellent band matching between Ag3PO4 and ZnO. This work paves a new way for future design of highly efficient visible‐light induced antibacterial agents.