Determination of ideal Mg–35Zn–xCa alloy depending on Ca concentration for biomaterials

Mg is a potential material for orthopedic and craniofacial implants. However, the failure of peri-implant osseointegration often occurs because pure Mg corrodes rapidly and has low mechanical strength. This study aimed to overcome these limitations via the development of various Mg-35Zn-xCa alloys. Electrochemical and immersion corrosion of these alloys were examined in simulated body fluid, and their cytotoxicity (cell proliferation and morphology) was assessed in a mouse osteoblast cell (MC3T3-E1). Structural analysis revealed that the Mg–35Zn–xCa alloys had a dendritic composition. The volume fractions of the second phases (Mg₂Ca and Ca₂Mg₆Zn₃) in the alloys increased with an increase in Ca concentration. The Mg–35Zn–xCa (x = 2, 3) alloys displayed greater hardness values (p < 0.05) and better corrosion resistance than the others; the Mg–35Zn–2Ca displayed the highest E_corr and lowest I_corr value. Cells of all groups had extended filopodia, thereby indicating that cell adhesion was intact. At each time point, the number of attached cells was the highest in the extracted media of Mg–35Zn–2Ca alloy, indicating that this material has good osteoconductivity. Based on the mechanical, corrosive, and biological properties, the Mg–35Zn–2Ca alloy can be a useful biomaterial for orthopedic implants.