Chondroitin sulfate and Cys-Ala-Gly peptides coated ZE21B magnesium alloy for enhanced corrosion resistance and vascular compatibility.

Coronary stents are widely used in the interventional treatment of cardiovascular disease. Biodegradable magnesium alloy stents are ideal candidates to replace traditional non-biodegradable stents due to their excellent mechanical properties and biodegradation. However, too fast degradation and poor biocompatibility limit the further clinical application of magnesium alloy stents. Herein, a composite coating consisting of an MgF layer, PDA layer, ChS, and CAG peptide was constructed on the Mg-Zn-Y-Nd (ZE21B) alloy to enhance its corrosion resistance, hemocompatibility, and cytocompatibility. The MgF and PDA layers in the composite coating could collectively enhance the corrosion resistance of ZE21B alloy, and the ChS and CAG peptides in the composite coating could improve the anticoagulant and pro-endothelialization capacity of ZE21B alloy. The corrosion current density of the modified ZE21B alloy was much lower than that of bare ZE21B alloy, proving the better corrosion resistance. Moreover, the excellent hemocompatibility of modified ZE21B alloy was verified by the lower levels of hemolysis rate, fibrinogen adsorption and denaturation, and platelet adhesion and activation. Furthermore, the composite coating could selectively promote the adhesion, proliferation, migration, and competitive growth of endothelial cells rather than smooth muscle cells on the ZE21B alloy owing to the synergistic biological effects of ChS and CAG peptides. The ChS/CAG modified samples also exhibited excellent biosafety and histocompatibility in vivo implantation experiments. The composite coating significantly improved the corrosion resistance and biocompatibility of ZE21B alloy, and provided a simple and effective strategy for developing degradable vascular stents.