Improved corrosion resistance and biocompatibility of a calcium phosphate coating on a magnesium alloy for orthopedic applications

Abstract

In this study a calcium phosphate (Ca-P) coating was fabricated on the surface of an AZ31 alloy by a chemical deposition process, and the in vitro and in vivo studies were carried out on a Ca-P-coated and uncoated AZ31 alloy to determine the effect of Ca-P coating on the corrosion behavior and biocompatibility of the AZ31 alloy. The morphology and composition of the Ca-P coating were characterized by scanning electron microscopy and energy dispersive spectroscopy. The corrosion behavior of the Ca-P coating was evaluated by a static immersion test and the effects of the Ca-P coating on biocompatibility were also investigated by in vitro cell experiments and in vivo animal experiments. The results indicated that the Ca-P coating reduced the in vitro and in vivo corrosion rates of the AZ31 alloy. Cell experiments showed significantly good adherence and high proliferation on the Ca-P-coated AZ31 alloy than those on the uncoated AZ31 alloy (P < 0.05). The blood cell aggregation tests showed that the Ca-P-coated AZ31 alloy had decreased the blood cell aggregation compared to the uncoated AZ31 alloy. The animal experiments showed that the uncoated AZ31 alloy degraded more rapidly than the Ca-P-coated AZ31 alloy and the Ca-P coating provided significantly good biocompatibility, thus suggesting that the Ca-P coating not only slowed down the corrosion rate of the AZ31 alloy, but also improved its biocompatibility. Therefore, the Ca-P-coated AZ31 alloy can be considered as a promising biomaterial for orthopedic applications.