Antibacterial and Osteoinductive Ti Implants Derived from MOF-Engineered Magnesium Oxide

Ti-based implants are widely applied in orthopedic repair and reconstruction, but their intrinsic bioinertness and susceptibility to implant-associated infection (IAI) remain major clinical challenges. To simultaneously improve antibacterial activity and osteogenic performance, we developed a structurally uniform and morphologically controllable MgO functional coating (Ti-MC) on Ti using a metal-organic framework (MOF)-derived strategy. Ti-MC exhibits a dual-mode antibacterial effect: (i) creating a sustained weakly alkaline microenvironment that directly induces reactive oxygen species (ROS) generation in bacteria, causing membrane disruption and (ii) activating neutrophil extracellular traps (NETs) formation to achieve immune-mediated antibacterial activity. This synergistic mechanism effectively inhibited both Staphylococcus aureus and Escherichia coli in vitro. In addition, Ti-MC demonstrated excellent cytocompatibility and provided sustained Mg²⁺ release, which, together with the alkaline environment, enhanced osteogenic outcomes by upregulating bone-related genes, stimulating alkaline phosphatase activity, and promoting mineralized nodule formation. In vivo studies using an infectious bone defect model further confirmed that Ti-MC reduced bacterial colonization, increased NETs expression, and significantly promoted new bone formation and osseointegration without systemic toxicity. Collectively, Ti-MC integrates direct antibacterial mechanisms with NET-associated immune-mediated antibacterial activity and osteogenic enhancement, highlighting its strong potential for clinical application in preventing IAI and improving bone healing.