Surface microstructure and cell compatibility of calcium silicate and calcium phosphate composite coatings on Mg–Zn–Mn–Ca alloys for biomedical application

A calcium silicate and calcium phosphate (CaSiO3/CaHPO4·2H2O) composite coating was applied by a chemical reaction to Mg–Zn–Mn–Ca alloy to improve its biocompatiblity. The surface microstructure was observed by scanning electronic microscopy (SEM) and the surface bioactivity was assessed by a cell interaction experiment. SEM observation showed that a microporous layer was formed on the surface of Mg–Zn–Mn–Ca alloy. It was shown by XRD that the reaction layer was mainly composed of CaHPO4·2H2O and a small amount of CaSiO3. In vitro cell experiments indicated that osteoblasts showed good adhesion, high growth rates and proliferation characteristics on the coated Mg–Zn–Mn–Ca alloy, indicating that the surface cytocompatibility of Mg–Zn–Mn–Ca alloy was significantly improved by the calcium phosphate coating.