In vitro investigation on microstructure, bio-corrosion properties and cytotoxicity of as-extruded Mg–5Sn–xIn alloys

Abstract

The microstructure, bio-corrosion properties and cytotoxicity of as-extruded Mg–5Sn–xIn (x = 0, 1, 2, 3, 4, all in wt%) alloys were investigated in vitro for biomedical applications. The results show that the microstructure of all alloys exhibits a partially recrystallized structure, and the area fraction of dynamically recrystallized (DRXed) grains increases with In addition. Mg2Sn particles are mostly precipitated at DRXed grains. Weight loss and potentiodynamic polarization measurements show that the bio-corrosion resistance of as-extruded Mg–5Sn–xIn alloys is enhanced with increasing In content as a result of cathodic reaction being hindered by indium oxide deposition on the alloy surfaces. The Mg–5Sn–4In alloy exhibits the minimum corrosion rate of 0.36 mm/y after immersion in Hank’s solution for 15 days. The cytotoxicity tests reveal that the as-extruded Mg–5Sn–xIn alloys do not induce toxicity to murine fibroblast cells (NIH3T3) and Human Umbilical Vein Endothelial Cells (HUVECs). The HUVECs morphology is ameliorated in the alloys with In addition, which is greatly associated with decreasing corrosion rate. Thus, this study uses In as an effective alloying element to tune the corrosion property of Mg–Sn based alloys with low degradation and excellent cytocompatibility.