Antibacterial and osteogenic gain strategy on titanium surfaces for preventing implant-related infections

Infection and insufficient osseointegration are the primary factors leading to the failure of titanium-based implants. Surface coating modifications that combine both antibacterial and osteogenic properties are commonly employed strategies. However, the challenge of achieving rapid antibacterial action and consistent osteogenesis with these coatings remains unresolved. In this study, a functional composite coating (PDA/PPy@Cu/Dex) was prepared on titanium surfaces using layer-by-layer self-assembly and electrochemical deposition techniques. The hydroxyl groups grafted by polydopamine's (PDA) self-polymerization and the enhanced conductivity and uniform electric field distribution provided by polypyrrole (PPy) allowed for the even dispersion of copper nanoparticles and dexamethasone (Dex) on the titanium surface. This synergistically coupled the photothermal ion antibacterial properties of copper nanoparticles with the osteogenic promotion of dexamethasone. In vitro antibacterial experiments revealed that the heat generated by photothermal effects and reactive oxygen species enhanced the antibacterial activity of copper ions, reducing the antibacterial time to six h and achieving antibacterial enhancement. In vitro cell experiments showed that the long-term slow release of copper ions and dexamethasone enhanced the osteogenic differentiation of stem cells, thereby achieving osteogenic benefits. Moreover, in vivo toxicity experiments demonstrated that the composite coating had no adverse effects on normal tissues. Therefore, the antibacterial and osteogenic enhancement strategy for titanium surfaces presented in this study offers a new potential approach for preventing implant-associated infections.