Formation Mechanism, Corrosion Behavior, and Cytocompatibility of Microarc Oxidation Coating on Absorbable High-Purity Zinc.

Microarc oxidation (MAO) has been regarded as one of the most effective techniques to suspend the corrosion rate of Mg-based alloys. In this research, MAO coating was successfully constructed on the surface of high-purity Zn for biomedical purpose. The microstructure, composition, corrosion behavior, and biocompatibility of MAO-coated samples were investigated. It was found that micro/nano pores were homogeneously distributed on the surface after MAO treatment in the electrolyte containing calcium and phosphorus components with pore size ranging from submicron scale to several micrometers. The MAO coating can modulate the corrosion behavior of pure Zn substrate by means of chemical dissolution and galvanic corrosion between coating and substrate. MG63 cells cultured in the 100% extracts of MAO-coated sample exhibited significant cytotoxicity due to stimulated cell apoptosis induced by high concentration of released Zn2+, whereas excellent cytocompatibility was observed for 20% extracts. Meanwhile, cell adhesion was promoted on the porous structure generated during MAO process. These results suggested MAO treatment can achieve an accelerated corrosion adjustment, as well as a better cell adhesion on pure Zn.