Endothelium-Mimicking with NO-generating coating on bioabsorbable magnesium alloy for improving corrosion resistance and biological responses of vascular stents

A multifunctional, anti-corrosive, and bioactive coating on magnesium-based implants surface is favorable for vascular remodeling and recovery of normal physiological functions. In general, the introduction of biomolecules to selectively inhibit smooth muscle cells (SMCs) proliferation and support endothelial cells (ECs) growth has been extensively studied. However, the regulatory role of the biomolecules needs to face the complex pathological microenvironment caused by stent implantation, such as oxidative stress, inflammation, hypercoagulation and cell proliferation disorder. Here, an endothelium-mimicking surface is designed, which can generate nitric oxide (NO) through catalyzing by copper ion (Cu2+) and the endothelial glycocalyx macromolecule hyaluronic acid (HA). Cu2+ is coordinated with epigallocatechin gallate (EGCG) to form a metal-phenolic network (EGCG-Cu), which should hold the anti-inflammatory and antioxidant activities. EGCG-Cu and HA are loaded in silk fibroin (SF), then the SF-based coating is fabricated via facile spinning assembly on fluorinated ZE21B alloy. The results demonstrated that the SF-based coating is homogeneous and dense, and the corrosion current density is decreased from 84.2 μA/cm2 of the ZE21B substrate to 0.202 μA/cm2. This coating promoted the growth of ECs while reduced the infiltration and activation of macrophages. The desirable NO-releasing ability inhibits platelet aggregation and activation, meanwhile suppresses the over-proliferation of SMCs. It offers great possibilities for reducing neointimal hyperplasia in vivo. This multi-functional coating may provide a new solution to address the deficiency of current magnesium-based vascular stents.