Osteogenic and pH stimuli-responsive self-healing coating on biomedical Mg-1Ca alloy

摘要

Various coatings have been used to slow down the corrosion rate of biomedical magnesium alloys. However, these coatings usually act only as passive barriers. It is much more desirable to endow such coatings with active, biocorrosion-responsive self-repairing capacity. In the present work, a self-healing coating system (denoted as "silk-PA") was constructed in the form of a sandwich architecture of fluoride precoating (bottom), silk-phytic acid (PA) coating (middle), and silk fibroin coating (top). Here, PA was loaded in the middle coating as a corrosion inhibitor by harnessing its strong chelating ability toward dissolving Mg2+ and Ca2+ ions. The self-healing property was evaluated by scratch and SVET tests, and the corrosion resistance was evaluated by in vitro immersion and electrochemical measurements. The results showed that the silk-PA manifested intriguing self-healing capacity with pH responsiveness, hence profiting the corrosion resistance of the Mg-1Ca alloy. The biocompatibility and osteogenic activity of the coating system were further evaluated using MC3T3-E1 cells, and it demonstrated favorable responses in multiple cellular behaviors, i.e., adherence, spreading, proliferation, and differentiation. These findings open new opportunities in the study of self-healing coatings for protection against corrosion in biomedical Mg alloys.