A Study on the Biocompatibility of MgO Coating Prepared by Anodic Oxidation Method on Magnesium Metal

Magnesium (Mg), is widely used for the bone repair in oral and orthopedic application due to excellent bioactivity, degradation and biocompatibility. However, the range of application is greatly limited because of the rapid degradation of Mg metal in the body. Surface modification is an effective method to enhance the corrosion resistance and reduce the degradation rate of Mg metal. In the present study, pure Mg metal (P-Mg) was subjected to alkali-heat treatment (AT-Mg) or anodic oxidation-heat treatment (AO-HT-Mg). Both AT-Mg and AO-HT-Mg had a layer of MgO on their surfaces after treatment. Then the effects of MgO coating on corrosion resistance, bioactivity, Mesenchymal Stem Cells’ (MSCs) proliferation, adhesion and osteogenic differentiation, and the bone repair capability of Mg metal were investigated. We found both AT-Mg and AO-HT-Mg had stronger corrosion resistance than P-Mg. MSCs on both AT-Mg and AO-HT-Mg had higher expression of proteins and genes of ALP, OCN, Col-I and Runx2 than those on P-Mg. They also showed better bone repair property than P-Mg in vivo. In general, MgO layer formed by anodic oxidation-heat treatment had better resistance and biocompatibility than that produced by alkali-heat treatment. This study indicated the MgO coating not only improved the corrosion resistance of Mg metal, but also promoted the osteogenic differentiation of MSCs and bone regeneration.