One-pot hydrothermal synthesis, in vitro biodegradation and biocompatibility of Sr-doped nanorod/nanowire hydroxyapatite coatings on ZK60 magnesium alloy

Abstract Hydroxyapatite (HA) coatings were widely used to improve the poor corrosion resistance, the osteoinduction and osseointegration ability of biodegradable magnesium alloys as biodegradable implants. To further improve the performance of the HA coated biodegradable magnesium alloys, strontium (Sr) was introduced in the HA coating through hydrothermal methods to partially replace the calcium ions. The growth mechanism, electrochemical properties, degradation, and cytocompatibility of the Sr-doped HA coated ZK60 magnesium alloys were investigated in details. The results show that with the addition of Sr element, the shape of the fabricated HA turned from nanorods into nanowires and the morphology of the coatings changed from a flower-like structure to a network structure. The electrochemical and immersion tests showed that the Sr doping can enhance the corrosion resistance of the HA coatings. Moreover, BMSCs cell culture results suggested that the addition of the trace element Sr can promote the cell adhesion and proliferation of HA coated biodegradable Mg alloys. This work provides a simple and efficient way to fabricate nanowired HA coating on biodegradable Mg alloys with improved biocompatibility and osteogenity. The Sr-doped HA coatings on biodegradable Mg alloys have shown a great potential for the orthopedic application.