Creation of Bioactive Ceramic Composite Coatings on Zn–Mn–Mg Alloy via Micro-arc Oxidation and Hydrothermal Treatment for Orthopedic Implant Applications

Abstract

Zinc alloys have emerged as promising biodegradable metals thanks to their critical physiological roles and encouraging degradation behavior. In this study, calcium phosphate (CaP) coatings were made on micro-arc oxidized Zn alloy using hydrothermal treatment (HT), which was motivated by the CaP-based minerals in natural bone tissue. The coating morphology was optimized by controlling the HT time, resulting in a homogeneous micro-CaP coating structure. The CaP coating significantly increased the cell viability and adhesion of MC3T3-E1 preosteoblasts and L-929 cells. Compared with the control group, the cell toxicity of the samples after MAO-HT was less, the number of cells was more, and the morphology was complete. Cell adhesion showed that the distribution of cells increased with the increase of HT time. In addition, the CaP coating significantly reduced the Zn ion release from the bulk material during the degradation process, resulting in a much lower Zn concentration and pH change in the surrounding environment. The micro-CaP coating structure and the regulated release of zinc ions are primarily responsible for the enhanced cytocompatibility and biomineralization of CaP-coated Zn biomaterials. In summary, the CaP coating on Zn-based biomaterial appears to be a viable approach to enhance its biocompatibility and to control its degradation rate. After that, the biocompatibility of the material can be improved by controlling the surface morphology of the material to adapt to the complex human environment.