Oxygen vacancy boosting Fenton reaction in bone scaffold towards fighting bacterial infection

Bacterial infection is a major issue after artificial bone transplantation due to the absence of antibacterial function of bone scaffold, which seriously causes the transplant failure and even amputation in severe cases. In this study, oxygen vacancy (OV) defects Fe-doped TiO₂ (OV-FeTiO₂) nanoparticles were synthesized by nano TiO₂ and Fe₃O₄ via high-energy ball milling, which was then incorporated into polycaprolactone/polyglycolic acid (PCLGA) biodegradable polymer matrix to construct composite bone scaffold with good antibacterial activities by selective laser sintering. The results indicated that OV defects were introduced into the core/shell-structured OV-FeTiO₂ nanoparticles through multiple welding and breaking during the high-energy ball milling, which facilitated the adsorption of hydrogen peroxide (H₂O₂) in the bacterial infection microenvironment at the bone transplant site. The accumulated H₂O₂ could amplify the Fenton reaction efficiency to induce more hydroxyl radicals (·OH), thereby resulting in more bacterial deaths through ·OH-mediated oxidative damage. This antibacterial strategy had more effective broad-spectrum antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). In addition, the PCLGA/OV-FeTiO₂ scaffold possessed mechanical properties that match those of human cancellous bone and good biocompatibility including cell attachment, proliferation and osteogenic differentiation.