Facile one-pot construction of copper-loaded polydopamine films on NiTi alloy for adjustable antibacterial activity and enhanced corrosion resistance

Abstract

Nickel–titanium (NiTi) alloys are widely employed as implantable devices, but their intrinsic poor antibacterial activity and Ni-ion release remain a major challenge. Leveraging copper's antibacterial efficacy, we developed a facile one-pot route to construct copper-loaded polydopamine films on NiTi alloy (Cu@PDA/NiTi). In a dopamine–CuSO₄ mixture, dopamine simultaneously polymerizes and reduces Cu²⁺, the resulting Cu²⁺ coordinates with PDA to form a metal-phenolic network (MPN), which incorporates both Cu²⁺ and Cu nanoparticles (NPs). By tuning CuSO₄ concentration (C_CuSO4) from 1 to 30 mM, the Cu@PDA/NiTi possesses adjustable Cu content and antibacterial potency. Antibacterial ratios toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reach 46.3–99.4% and 47.5–97.3%, respectively, while Ni-ion release is markedly suppressed and corrosion resistance significantly enhanced. In vitro and in vivo assays confirm excellent biosafety. This scalable strategy offers a practical avenue for customizable antibacterial NiTi implants and inspires the design of next-generation functional biomaterials.