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

## TL;DR

A new method creates copper-loaded films on NiTi alloys to improve antibacterial properties and reduce corrosion, making them better for implants.

## Contribution

A scalable one-pot method to create Cu@PDA/NiTi films with tunable antibacterial activity and enhanced corrosion resistance.

## Key findings

- Antibacterial ratios of 46.3–99.4% against E. coli and 47.5–97.3% against S. aureus were achieved.
- Ni-ion release was significantly suppressed, and corrosion resistance was enhanced.
- In vitro and in vivo tests confirmed the biosafety of the Cu@PDA/NiTi films.

## 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 (CCuSO4) 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.

A facile one-pot construction of Cu@PDA film on NiTi alloy imparts adjustable antibacterial activity, enhanced corrosion resistance, and inhibited Ni-ion release, addressing key limitations for implant applications.