Construction of a Carbon Monoxide-Releasing Bioactive Hydrogel Coating on the Magnesium Alloy Surface for Better Corrosion Resistance, Anticoagulant Properties, and Endothelial Cell Growth

In this study, we first fabricated a crosslinked hydrogel coating by polymerizing methacryloyloxyethyl sulfonyl betaine and acrylamide (SBMA) on the magnesium (Mg) alloy surface employing ultraviolet (UV) polymerization. Bivalirudin and CO-releasing molecules (CORM-401) were further grafted onto the hydrogel coating surface to acquire a multifunctional biocompatible coating capable of releasing CO to augment corrosion-resisting properties and biocompatibility. The findings verified that the bioactive hydrogel coating significantly increased the corrosion potential and reduced the corrosion current, thereby improving the anticorrosion performance. Meanwhile, owing to the excellent hydrophilicity, the antifouling performance of the hydrogel coating, and the excellent anticoagulant performance of bivalirudin, the hydrogel coating significantly reduced the fibrinogen adsorption, platelet adhesion and activation, and hemolysis occurrence, displaying excellent ability to inhibit blood clotting. Moreover, endothelial cell (EC) experimental results demonstrated that the hydrogel coating could significantly promote EC growth, displaying great potential to induce re-endothelialization after implantation. Specifically, in the presence of cysteine capable of catalyzing CO release, the anticoagulant performance and ability to promote EC growth were further improved significantly. Therefore, the study offers an effective strategy to prepare a hydrogel coating capable of releasing CO to improve the corrosion-resisting performance and biocompatibility of Mg alloys, which is anticipated to be applied in the surface modification of Mg alloy intravascular stents.