Synergistic photothermal and photodynamic nanocoatings on titanium implants for rapid bactericidal action and enhanced osteoinductive activity.

Abstract

The long-term success of titanium (Ti) implants in dental and orthopedic applications is frequently undermined by the dual challenges of interfacial infection and inadequate osseointegration. Consequently, there is an imperative need for multifunctional coatings that simultaneously exert antibacterial and osteoinductive activities. In this study, photothermal agent polydopamine (PDA) and photosensitizer rose bengal (RB) were facilely co-immobilized onto the titanium dioxide nanotube (TNT) arrays via mussel-inspired chemistry and amide coupling. This integrated platform enables highly efficient synergistic photothermal (PTT) and photodynamic (PDT) bacterial inactivation. The resulting TNT-PDA-RB nanocoating exhibited exceptional photobactericidal efficacy (>99.99%) against both Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) in vitro under dual-wavelength irradiation (808 nm + 532 nm) for only 3 min. Furthermore, the coating demonstrated excellent cytocompatibility with preosteoblasts and negligible hemotoxicity against erythrocytes. In vivo rat subcutaneous infection model confirms its robust anti-infective performance, achieving a bacterial load reduction of 2.49 log (>99%) compared with pristine Ti implants. Concurrently, the nanocoating significantly promoted the alkaline phosphatase (ALP) activity and the extracellular matrix (ECM) mineralization of preosteoblasts, indicating enhanced osteoinductive properties. This multifunctional TNT-PDA-RB nanocoating offers a robust and versatile strategy for augmenting the clinical performance of Ti implants.