Growth, in vitro biodegradation and cytocompatibility properties of nano-hydroxyapatite coatings on biodegradable magnesium alloys

Abstract Due to good biocompatibility and mechanical properties, magnesium (Mg) and its alloys are considered as promising degradable materials for orthopedic applications. However, the rapid degradation rate of the magnesium-based implants in vivo has become the main limitation hindering their applications. We report here the successful fabrication of the nano-whisker/wire-like hydroxyapatite (nHA) coatings on Mg alloy (ZK60) substrates for controlling the biodegradation of Mg alloy while improving its cytocompatibility for orthopedic applications, using a simple one-step hydrothermal treatment process in aqueous solution. The formation mechanism of HA coatings on Mg substrate is discussed in details. The surface morphology and microstructure of the coatings can be regulated by varying the deposition time. The biodegradation of ZK60 alloy was greatly restrained by the nano-whisker/wire-like HA coatings. Improved cytocompatibility was observed in nano-whisker/wire-like HA coated ZK60 samples and the cytotoxicity of ZK60 samples coated for 2 and 2.5 h are in grade 1. Results indicate that coatings with nano-whisker/wire-like HA are promising for improving the in vitro biodegradation and cytocompatibility properties of Mg-based orthopedic implants and devices.