Synergistic Bacteria Killing through Photodynamic and Physical Actions of Graphene Oxide/Ag/Collagen Coating

Researchers have widely agreed that the broad spectrum antibacterial activity of silver nanoparticles (AgNPs) can be predominantly ascribed to the action of Ag⁺. This study marks the first report detailing the rapid and highly efficient synergistic bacteria killing of AgNPs, which is achieved by inspiring AgNPs' strong photocatalytic capability to rapidly produce radical oxygen species using 660 nm visible light together with the innate antimicrobial ability of Ag⁺. These AgNPs were uniformly distributed into well-defined graphene oxide (GO) nanosheets through an in situ reduction of Ag⁺ and subsequently wrapped with a thin layer of type I collagen. In vivo subcutaneous tests demonstrated that 20 min irradiation of 660 nm visible light could achieve a high antibacterial efficacy of 96.3% and 99.4% on the implant surface against Escherichia coli and Staphylococcus aureus, respectively. In addition, the collagen could reduce the coatings' possible cytotoxicity. The results of this work can provide a highly effective and universal GO-based bioplatform for combination with inorganic antimicrobial NPs (i.e., AgNPs) with excellent photocatalytic properties, which can be utilized for facile and rapid in situ disinfection, as well as long-term prevention of bacterial infection through the synergistic bacteria killing of both 660-nm light-inspired photodynamic action and their innate physical antimicrobial ability.