Engineering Metallic Implants with Self-Catalytic Degradable Bionanozyme Coating and Ion-Releasing Biointerface for Bioadaptive Anti-infective and Osteogenic Functionality

Implant-associated infections and poor osseointegration remain major challenges for Ti-based indwelling devices. To address these, we developed a multifunctional implant coating integrating photothermal-enhanced nanobioenzymatic catalysis with degradable release of bioactive components for staged antibacterial and osteogenic functions. The coating consisted of a Ca²⁺/Cu²⁺-doped micro/nanostructured titanate layer overlaid with a bionanozyme (HMG)-loaded, alendronate-modified hyaluronic acid (AHA) matrix, anchored via Ca²⁺-alendronate chelation. The bionanozyme HMG comprised glucose oxidase (GOx) encapsulated in hollow MnO₂ nanozymes and stabilized by tannic acid (TA). Upon infection, GOx-generated H₂O₂ (from glucose oxidation) was converted into •OH via a TA-mediated Cu⁺-based Fenton-like reaction, enhanced by MnO₂'s photothermal activity. MnO₂ and TA also acted as potential ROS scavengers to alleviate inflammation post infection resolution. Notably, bacteria-triggered top-layer degradation would cause interface self-renewal, releasing HMG for distal antibacterial action and exposing the micro/nanostructured titanate underlayer to favor cell adhesion and sustained Cu²⁺/Ca²⁺ release for osteogenesis. Systemic in vitro/ovo/vivo studies confirmed the multifaceted antibacterial killing, accelerated mineralization, and improved tissue healing/biointegration, alongside favorable biological compatibility. This work presents a nanobioenzymatic coating strategy with multilayer design, aimed at catalytically active implants with self-adaptive interfaces that can accommodate evolving anti-infective and tissue-regenerative demands.