Bifunctional Metal Ion-Enhanced PDA-Coated Titanium for Superior Osteogenic and Antimicrobial Performance

Titanium (Ti) implants serve as a popular solution for tooth replacement, because they combine excellent mechanical properties with high biocompatibility. However, the biologically inert nature of titanium surfaces restricts their osteogenic capacity and renders them prone to bacterial colonization, elevating the risk of biofilm formation and implant-associated infections. Surface modification of titanium implants is essential to overcoming these limitations. To optimize the titanium surface functionality, this study employed a polydopamine (PDA) coating strategy combined with subsequent incorporation of copper and manganese ions. We prepared Ti-PDA and then fabricated Ti-PDA-Cu and Ti-PDA-Cu/Mn samples. Material characterization revealed that Ti-PDA-Cu/Mn exhibits favorable surface wettability and biocompatibility, along with sustained and stable release of Cu²⁺ and Mn²⁺ ions. Experiments in vitro showed that Ti-PDA-Cu/Mn had good antimicrobial activity against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>, significantly promoted protein adsorption, osteoblast adhesion, proliferation, and mineralization, and upregulated the expression of osteogenic genes. A promising strategy has been established through this bifunctional modification to simultaneously enhance the osteogenic and antimicrobial properties of titanium implants.