Reduced graphene oxide-mediated electron-hole separation using titanium dioxide increases the photocatalytic antibacterial activity of bone scaffolds

Fast electron–hole recombination issues during titanium dioxide (TiO 2 ) photocatalysis limit its application in preventing bacterial infection during bone defect repair. In this study, TiO 2 @reduced graphene oxide (rGO) composites were synthesized using a hydrothermal method in which rGO, which possesses very high electrical conductivity, promotes the separation of photoelectron–hole pairs of TiO 2 , thus improving the efficiency of photocatalytic production of reactive oxygen species (ROS). Subsequently, TiO 2 @rGO composites were introduced into poly-L-lactic acid (PLLA) to prepare bone scaffolds with photocatalytic antibacterial function via selective laser sintering. The results showed that TiO 2 grew on the surface of rGO and formed a covalent bond connection (Ti–O–C) with rGO. A decreased electrochemical impedance of TiO 2 @rGO composites was observed, and the transient photocurrent intensity increased from 0.05 to 0.5 µA/cm 2 . Analysis of electron spin resonance found that the photocatalytic products of TiO 2 were ·OH and ·O 2 − , two kinds of ROS capable of killing bacteria via disrupting the structure of the bacterial membrane in vitro. Antibacterial experiments showed that the PLLA/TiO 2 @rGO scaffolds had good antibacterial properties against Escherichia coli and Staphylococcus aureus . Finally, we report that these scaffolds exhibited both enhanced mechanical properties due to the addition of TiO 2 @rGO as a reinforcement material and good biocompatibility during cell proliferation.