Microstructure, Mechanical Properties, In Vitro Degradation and Cytotoxicity of Mg-4Zn-3HA Alloy for Biodegradable Implant Materials

Abstract

In this study, a kind of Mg-4Zn-3HA alloy was investigated as a biodegradable material. Magnesium alloys can be totally degraded in the body, and their corrosion products are not deleterious to the surrounding tissues. We conducted a comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments, and in vitro cytotoxicity evaluations of Mg-4Zn-3HA alloy. Our observations of the microstructure show that the Mg-4Zn-3HA alloy is porous, and its structural characteristic resembling nature bone make this alloy suitable for use in implants. The results of in vitro degradation indicate that the corrosion resistance is improved with the extension of immersion time, and XRD and EDS analysis proves that the corrosion products on the surface of Mg-4Zn-3HA alloy contain hydroxyapatite (HA), Mg (OH) 2 and other magnesium-substituted calcium phosphate, which could reduce the degradation rate. The degradation process of magnesium alloy and the formation of corrosion layer are also discussed in this work. The corrosion products contain HA and Mg (OH) 2 , which can promote good biocompatibility. No significant cytotoxicity to MC3T3-E1 cells is detected in the extraction medium, and MC3T3-E1 cells are able to adhere and spread on the corrosion layer of the Mg-4Zn-3HA alloy. Mg-4Zn-3HA alloys have the potential to be used for biomedical applications.