In-vitro assessment of HA-Nb coating on Mg alloy ZK60 for biomedical applications

Magnesium (Mg) and its alloys have attracted a great deal of attention as next-generation biomaterials due to their highly appealing properties. However, the high corrosion kinetics and inadequate hemocompatibility have limited their widespread acceptance as implant materials. In this study, an attempt was made to improve the corrosion resistance and hemocompatibility of Mg alloy ZK60 by coating it with niobium (Nb)-reinforced hydroxyapatite (HA). The Nb-reinforced HA (HA-Nb) coating was obtained through plasma spray technique by varying weight percent (wt%) of Nb-reinforcement in HA at three levels (10 wt%, 20 wt%, and 30 wt%). Nb-reinforcement had a more pronounced effect on the microhardness and wettability as compared to the surface roughness of the coating. The corrosion investigation revealed that the HA-Nb coatings were more effective than the pure HA and Nb coatings for inhibiting the rapid corrosion of the Mg alloy. With the progressive increment of the Nb-content in HA, protection efficiency (Pe) for HA-Nb coatings increased (similar to 4%, 12% and 18% for HN1, HN2, and HN3, respectively) in comparison to pure HA coating. The HA-Nb coatings exhibited no adverse effects on the erythrocytes and the hemolysis rate (HR) was within the domain of safe value (<5%) for implant materials.