Investigation of In Vitro Cytocompatibility of Zinc-Containing Coatings Developed on Medical Magnesium Alloys

In a neutral solution, we investigated the effects of Na₂[ZnEDTA] concentrations at 0, 6, 12, 18, and 24 g/L on surface morphology, chemical composition, degradation resistance, and in vitro cytocompatibility of micro-arc oxidation (MAO) coatings developed on WE43 (Mg-Y-Nd-Zr) magnesium alloys. The results show that the enhanced Na₂[ZnEDTA] concentration increased the Zn amount but slightly decreased the degradation resistance of MAO-treated coatings. Among the zinc-containing MAO samples, the fabricated sample in the base solution added 6 g/L Na₂[ZnEDTA] exhibits the smallest corrosion current density (6.84 × 10^-7 A·cm^-2), while the sample developed in the solution added 24 g/L Na₂[ZnEDTA] and contains the highest Zn content (3.64 wt.%) but exhibits the largest corrosion current density (1.39 × 10^-6 A·cm^-2). Compared to untreated WE43 magnesium alloys, zinc-containing MAO samples promote initial cell adhesion and spreading and reveal enhanced cell viability. Coating degradation resistance plays a more important role in osseogenic ability than Zn content. Among the untreated WE43 magnesium alloys and the treated MAO samples, the sample developed in the base solution with 6 g/L Na₂[ZnEDTA] reveals the highest ALP expression at 14 d. Our results indicate that the MAO samples formed in the solution with Na₂[ZnEDTA] promoted degradation resistance and osseogenesis differentiation of the WE43 magnesium alloys, suggesting potential clinic applications.