Abstract
Fast degradation of Mg alloys and slow bone regeneration process largely impede their clinical applications as one kind of degradable metallic orthopedic implants. In current study, novel calcium carbonate (CaCO3) coatings are prepared via the hydrothermal method and optimized via the addition of glutamate acid (Glu) or dopamine (DOPA) to improve the degradation and biological performance of the MgZnCa alloy. The results revealed that the CaCO3 coating was mainly composed of rhombohedral calcite aggregates and deposited rod-like aragonite. Whereas, the introduction of Glu or DOPA stabilized plate-like vaterite via the adsorption or incorporation of organic molecules, and suppressed the deposition of rod-like aragonite on CaCO3 hybrid coating with lower roughness, higher adhesion strength and thickness. Thus, CaCO3 hybrid coatings endowed the MgZnCa alloy with more favorable in vitro degradation resistance. Furthermore, all CaCO3-based coatings showed good in vitro cytocompatibility, while CaCO3@Glu hybrid coating exhibited the best in vitro osteogenic activity of osteoblasts, attesting the synergistic effect of Glu and vaterite on the biological activity of the MgZnCa alloy. In vivo results verified the significantly inhibited degradation and promoted osteogenesis of the CaCO3@Glu hybrid coating. These results provide important guidelines and rationality for the further application of the CaCO3-based coatings on orthopedic implants towards more excellent clinical performance.
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