Combined Antibacterial-Osteogenic Modulation of Orthopedic Implants through Thermo-Induced Bioinspired Interfacial Activation

Periprosthetic joint infection (PJI) and aseptic loosening remain the leading causes of arthroplasty failure, yet existing antimicrobial coatings suffer from limited durability and poor osteointegration. Here, we report a thermo-bioactivated nanohybrid coating (Ti-AQR) that integrates photothermal conversion with bioactive functionalities to achieve combined antibacterial and osteogenic modulation. Ti-AQR could provide stable and durable near-infrared (NIR)-induced mild photothermal performance by Au NRs, a typical photothermal agent, while a chitosan derivative (QTR) with quaternary ammonium groups and RGD motifs delivered both bactericidal and osteoinductive functions, which were promoted by the mild photothermal effect. Under mild photothermal stimulation, the effect of bacterial membrane disruption by the alkyl chains in quaternary ammonium groups was amplified by mild heat, lowering the temperature threshold for effective bacterial killing. Concurrently, mesenchymal stem cell adhesion, osteogenic differentiation, and matrix mineralization were enhanced by the RGD motifs of Ti-AQR combined with subhyperthermic heat. Ti-AQR eradicated >99.9% of Staphylococcus aureus and >97% of Escherichia coli through combined heat-assisted contact killing, while markedly upregulating osteogenic markers, alkaline phosphatase activity, and calcification. Mechanistically, the mild photothermal effect of Ti-AQR activated the MAPK pathway and upregulated heat shock protein-related genes. In animal experiments, Ti-AQR implants simultaneously prevented early-stage infection and significantly improved bone-implant integration. This thermo-induced interfacial synergy establishes a versatile strategy for functionalization of orthopedic implants, offering dynamic, controllable, and biocompatible solutions against both infection and loosening.