Bioactivity enhancement by Sr doped Zn-Ca-P coatings on biomedical magnesium alloy

The effect of strontium doped Zn-Ca-P (ZCP) coating by chemical conversion technique on the biodegradation of AZ31 alloy was evaluated. The coating formed with 1.5 wt.% Sr and 20 min phosphating time at 50 degrees C with pH 2.5 completely covers the alloy surface. The Sr doped coated sample also showed very low evolved hydrogen gas and pH change than the ZCP coatings suggested that the degradation of the alloy was extremely controlled. The in vitro bioactivity studies in simulated body fluid exhibits deposition of calcium phosphate phases with Ca/P ratio of 1.55 which is close to that of hydroxyapatite, mineral component of bone. Cytotoxicity evaluation with L929 cells showed higher cell viability of the Sr doped coatings compared to ZCP coatings. (C) 2019 Published by Elsevier B.V. on behalf of Chongqing University.