Reduced graphene oxide-mediated electron-hole separation in titanium dioxide for boosting photocatalytic antibacterial activity of bone scaffold

Abstract Fast electron-hole recombination in the photocatalysis process of titanium dioxide (TiO 2 ) limits its antibacterial properties although TiO 2 has great potential for preventing bacterial infection in bone defect repair because it has the ability to generate reactive oxygen species under ultraviolet irradiation to destroy bacteria. In this study, TiO 2 @rGO were synthesized through a hydrothermal method, where TiO 2 was grown on reduced graphene oxide (rGO). Subsequently, TiO 2 @rGO composite powders were introduced into poly-l-lactic acid (PLLA) and then selective laser sintering was as a method for scaffold fabrication with photocatalytic antibacterial ability. It showed that TiO 2 grew on the surface of rGO and formed a covalent bond connection (Ti-O-C) with rGO. The excellent conductivity of rGO promoted the separation of electron-hole pairs generated by TiO 2 photocatalysis, resulting in a decrease in photoluminescence intensity that indicated an enhancement of TiO 2 photocatalytic activity. In vitro antibacterial experiments indicated that the scaffold photocatalysis produced ·OH and ·O 2 − under ultraviolet irradiation, which destroyed the cell membrane structure and had antibacterial effects on both E. coli and S. aureus. Additionally, the scaffold exhibited enhanced mechanical properties due to the addition of TiO 2 @rGO as reinforcement phase and good biocompatibility for cell activity and proliferation.