Copper-loaded chitosan coating for improved in-vitro corrosion resistance and endothelialization of magnesium alloy stents

Abstract

For degradable magnesium alloy stents, excellent corrosion resistance and rapid endothelialization are two essential properties. In this paper, we plan to use a copper-loaded chitosan coating to accelerate the endothelialization process of the stent, which not only improves the biocompatibility of the magnesium alloy stent, but also its corrosion resistance by improving the service environment in vivo. Copper is an impurity in magnesium alloys, so how copper-containing coatings affect the corrosion resistance of magnesium alloy stents is the focus of this paper. The corrosion properties of the material were characterized by electrochemical experiments, immersion experiments, and in vitro cellular experiments characterized the effect of the copper-loaded coating on endothelial cells. The results showed that the Icorr of the copper-loaded chitosan coated sample and the Icorr of the unloaded copper chitosan coated sample were both in the order of 10−8, and the decrease of the corrosion resistance of the magnesium alloy by the copper-containing chitosan composite coating was not significant, and it still had a protective effect on the magnesium alloy substrate. During the immersion process, magnesium and copper ions were slowly released, followed by the hydrogen released. In addition, the weight loss rate of different coated samples presented the tendency of slower at inital, faster at last, and the weight loss rate of 0.041% for the copper-loaded chitosan coated sample was not significantly different from that of 0.035% for the unloaded copper coating group, after 28 days of immersion. The in vitro degradation products of the copper-loaded composite coating on the surface of magnesium alloy were also analyzed by XRD and EPMA, which included Mg(OH)2, Mg3(PO4)2 and Ca3(PO4)2; in addition the degradation process was analyzed. The cellular experiments results showed that the copper-loaded magnesium alloy had a proliferation rate of 243.0% for endothelial cells, which indicated that the copper-loaded coating could endow magnesium alloy stent a good biofunctional properties.