Preparation of graphene oxide/polydopamine-curcumin composite nanomaterials and its antibacterial effect against Staphylococcus aureus induced by white light.

Curcumin (Cur) plays a key role in photodynamic antibacterial activity as a photosensitizer. On the other hand, the antimicrobial potential of graphene oxide (GO) has been reported controversially, and how to improve its antimicrobial ability has become an meaningful study. In this study, we prepared polydopamine-curcumin (PDA-Cur) by pi-pi stacking and loaded it onto the GO surface to obtain GO/PDA-Cur composite nanomaterials. GO/PDA-Cur was characterized by physical and optical means, and GO/PDA-Cur possessed good dispersion and stability in water. In vitro antibacterial results showed that GO/PDA-Cur mediated photodynamic therapy significantly reduced Gram-positive Staphylococcus aureus (S. aureus) by 4 orders of magnitude with a bactericidal rate of 99.99 %. The antibacterial mechanism stems from the fact that GO/PDA-Cur can generate reactive oxygen species (ROS) under white light irradiation (405-780 nm), which causes bacterial outer membrane breakage and cellular deformation. In addition, GO/PDA-Cur has good biocompatibility. The antibacterial ability of graphene oxide was significantly improved by combining it with PDA-Cur, which allows it to be used as a photodynamic antibacterial material.