Copper coating formed by micro-arc oxidation on pure Mg improved antibacterial activity, osteogenesis, and angiogenesis in vivo and in vitro.

Abstract

Micro-arc oxidation (MAO) was used to improve the resistance of pure magnesium (Mg). Copper (Cu), a good antibacterial, angiogenic, and osteogenic element, was added by reaction in a Cu-containing electrolyte to improve the osteogenic and pro-angiogenic activities of Mg. The surface microstructures of the resulting MAO were evaluated by a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) mapping. The release of Cu ions was detected by ICP-OES. The antibacterial activity of films with different concentrations of Cu ions was assessed against Staphylococcus aureus (S. aureus). The osteogenesis of films was confirmed by cell morphology and proliferation, ALP activity, alizarin red staining, and osteogenic-related gene expression in the MC3T3-E1 cell line. The angiogenesis of the films was tested in human umbilical vein endothelial cells (HUVECs) by cell migration, tube formation, and VEGF quantification in vitro, and by a chicken embryo chorioallantoic membrane (CAM) assay in vivo. The results showed that the microporous structure was shaped by MAO, and the Cu group was denser and more uniform. The Cu coating showed effective antibacterial activity against S. aureus while also enhancing osteogenesis and angiogenesis in vitro. According to the CAM assay, the Cu group showed not only biocompatibility but also a significant angiogenic response, which was consistent with in vitro studies. The findings indicate that a Cu coating on Mg-MAO enhances osteogenesis and angiogenesis.