Polydopamine-Cu(II) Ions Functional Coatings on Zinc Wire: Surface Characterization and Degradation Behavior

Bioactive surface modification of degradable zinc (Zn) vascular implants is essential for controlling biodegradation and supporting vascular healing. Here, we describe the fabrication of polydopamine coating (PDA-Cu) containing up to ∼0.8 wt % Cu²⁺ ions on Zn substrates using an immersion-assisted mussel-inspired polymerization strategy. The coating is composed of densely packed PDA-Cu nanospheres with diameters of ∼130-170 nm, exhibiting an even distribution of Cu ions within the PDA matrix via Cu²⁺-catechol coordination. Thirty-day leaching tests confirmed a steady release of 0.01-0.04 ppm of Cu ions per 5 days from Zn/PDA-Cu samples in Hank's balanced salt solution (HBSS). In vitro nitric oxide (NO) assay demonstrated enhanced catalytic NO generation in 1 mM SNAP (S-nitroso-N-acetylpenicillamine) solution. Additionally, the PDA-Cu coating reduced the Zn corrosion rate from ∼0.8 mm/year to ∼0.4 mm/year and increased its corrosion resistance in HBSS.