In-vitro and in-vivo evaluation of strontium doped calcium phosphate coatings on biodegradable magnesium alloy for bone applications

The objective of the present work was to investigate the in-vitro and in-vivo performance of strontium doped calcium phosphate (Ca-Sr-P) coatings on ZK60 magnesium (Mg) alloy for bone applications. A chemical immersion technique was employed to develop Ca-Sr-P coating on biodegradable Mg alloy. Surface morphology, chemical composition, phase, mechanical properties, wettability, in-vitro corrosion, cytocompatability, in-vivo degradation and biocompatibility of Ca-Sr-P coatings were studied. The Ca-Sr-P coating (similar to 20 mu m) exhibited a dense, crystalline, uniform, and crack-free surface. In-vitro studies revealed that the coating improved the corrosion resistance of Mg alloy and enhanced bioactivity. The surface coating also promoted the adhesion, proliferation, and osteogenic markers expression of MC3T3-E1 cells. The coating lowered the degradation rate in-vivo compared with Mg alloy. Higher bone formation and better ossteointegration was found around the coating than the Mg alloy after 4 weeks of implantation in a rabbit model. Thus, the Ca-Sr-P coating with a reduced degradation and improved biocompatibility could be used in Mg-based orthopedic implant applications.