Bivalirudin functionalized hydrogel coating capable of catalytical NO-generation for enhanced anticorrosion and biocompatibility of magnesium alloy.

Magnesium and its alloys are undoubtedly ideal candidates for manufacturing new bioabsorbable vascular stents thanks to their good bio-absorbability and better mechanical characteristics. However, the bottlenecks that restrict their clinical application, such as fast corrosion , poor hemocompatibility, and inferior surface endothelial regeneration ability, have not been resolved fundamentally. In this study, a polydopamine (PDA) intermediate layer covalently linked with acrylamide was first constructed on the alkali-heat-treated magnesium alloys, followed by polymerizing methacryloyloxyethyl sulfonyl betaine (SBMA) and acrylamide (AAM) to fabricate a hydrogel coating on the surface by ultraviolet (UV) polymerization. Finally, bivalirudin and selenocystamine were sequentially grafted onto the hydrogel coating surface to construct a multifunctional bioactive corrosion-resistant coating with excellent antifouling, anticoagulant performance, and catalytic liberation of NO (nitric oxide) to facilitate endothelial cell (EC) growth. The outcomes verified that the bioactive coating could not only significantly resist corrosion of magnesium alloys, but also had excellent hydrophilicity and the ability to selectively promote albumin adsorption, which could prevent platelet adhesion and activation and significantly diminish the hemolysis occurrence, thereby considerably facilitating its anticoagulant properties. At the same time, due to the hydrophilicity and extracellular matrix-like characteristics of the hydrogel coating, the coating could promote EC growth and upregulate the secretion of vascular endothelial growth factor (VEGF) and NO of endothelial cells (ECs). In the case of catalytic NO-liberation, the catalytic release of NO could further significantly improve blood compatibility, EC growth, and functional expressions of ECs. Therefore, the method in this study provides an effective strategy to fabricate the bioactive hydrogel coating that can simultaneously resist corrosion and enhance the biocompatibility of magnesium-based alloys, thereby effectively promoting research and application of magnesium alloy in intravascular stents.