Multifunctional MOF-based composite coating on Mg alloy for biodegradable orthopedic implants

To facilitate the application of Magnesium (Mg) alloys as biodegradable implants, multifunctional composite coating was fabricated by plasma electrolytic oxidation (PEO) in conjunction with hydrothermal and solvothermal methods on Mg-1Zn-1Gd (ZG11) alloy. The PEO coating was used as base layer, upon which a transition layer of ZnO was deposited by hydrothermal method. Finally, a metal organic framework (MOF, ZIF-8) outermost layer was synthetized by solvothermal method. It has been found that due to the introduction of MOF layer, the corrosion resistance, biocompatibility and even wear resistance of the coating was tremendously improved, which can primarily be attributable to the sealing and self-lubricating effects of ZIF-8 and the induced formation of hydroxyapatite (HAP) during degradation in simulated body fluid (SBF). Therefore, the present study spotlights the potential of MOF layer in the realm of biomaterials and holds considerable significance for the further development of biodegradable Mg alloys.