Tailored coating chemistry and interfacial properties for construction of bioactive ceramic coatings on magnesium biomaterial

Magnesium has the potential to replace materials currently used for medical implants, but its high corrosion rate limits its practical application. For the practical application purpose, a multilayer coating method that combined MgF₂ layer and the sol-gel-synthesized hydroxyapatite (HA) layer on Mg substrate was proposed in this study to enhance corrosion resistance and biocompatibility. As characterized by SEM, TEM and electrochemical test, the MgF₂ layer not only increases the interfacial stability during the coating process, but also provides a fluorine source that leads to the formation of low-solubility fluorine-substituted HA (FHA), resulting in excellent coating properties. The synthesized coatings were calcined at 400 and 500°C, respectively, to control their crystallinity and impurities. The results show that the corrosion resistance of the specimens calcined at 500°C was 11 times higher than that calcined at 400°C. MG63 cells cultured on the optimized HA/MgF₂ coatings were more viable than other surface. Furthermore, the spreading behavior of the cells was significantly higher on the optimized HA/MgF₂ coatings. These results suggest that the designed-multilayer process and optimized calcination temperature can effectively control the coating chemistry and interfacial properties, which improves biocompatibility and allows for orthopedic application.