Microstructure, Corrosion, and Biological Responses of Mg-Al-Zn-Sr-xCa Alloys for Bioresorbable Applications.

Mg-Al-Zn-Sr-Ca alloys with varying calcium content were prepared and examined for biomedical applications. Microstructural observations indicated grain refinement and increased second phase precipitation with increasing Ca content. Immersion test, potentiodynamic polarization study, and impedance spectroscopy revealed that Ca content up to 1 wt.% improved the corrosion response of Mg-Al-Zn-Sr-Ca alloys studied in this work. Due to the combined effect of grain refinement, second phase precipitate barrier, and protective layer formation, the corrosion rate dropped from 1.84 mm/year in alloy Ca0.2 to 1.01 mm/year in alloy Ca1.0. Biocompatibility was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Ca1.0 showed the highest cell attachment and proliferation density. Ca formed Mg₂Ca and improved the cell viability of the alloys. [ABSTRACT FROM AUTHOR]