Tuning the Bandgap of Photo-Sensitive Polydopamine/Ag₃PO₄/Graphene Oxide Coating for Rapid, Noninvasive Disinfection of Implants

Bacterial infection and associated complications are threats to human health especially when biofilms form on biomedical devices and artificial implants. Herein, a hybrid polydopamine (PDA)/Ag₃PO₄/graphene oxide (GO) coating is designed and constructed to achieve rapid bacteria killing and eliminate biofilms in situ. By varying the amount of GO in the hybrid coating, the bandgap can be tuned from 2.52 to 2.0 eV so that irradiation with 660 nm visible light produces bacteria-killing effects synergistically in concert with reactive oxygen species (ROS). GO regulates the release rate of Ag⁺ to minimize the cytotoxicity while maintaining high antimicrobial activity, and a smaller particle size enhances the yield of ROS. After irradiation with 660 nm visible light for 15 min, the antimicrobial rates of the PDA/Ag₃PO₄/GO hybrid coating against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> are 99.53% and 99.66%, respectively. In addition, this hybrid coating can maintain a repeatable and sustained antibacterial efficacy. The released Ag⁺ and photocatalytic Ag₃PO₄ produce synergistic antimicrobial effects in which the ROS increases the permeability of the bacterial membranes to increase the probability of Ag⁺ to enter the cells to kill them together with ROS synergistically.