Theoretical calculation-experimental collaborative design of integrated coating for degradation regulation and diagnosis-treatment of magnesium alloy for cerebrovascular stents.

INTRODUCTION: Magnesium (Mg) alloys, with favorable mechanical properties, biodegradability, and biocompatibility, are promising materials for cerebrovascular stents. However, rapid degradation, delayed endothelialization, and ischemia-reperfusion-induced microvascular injury limit their clinical application.

OBJECTIVES: This study aims to develop a composite coating that integrates corrosion inhibition and drug delivery functions to achieve degradation regulation, rapid endothelialization, and vascular protection of Mg-based cerebrovascular stents.

METHODS: The optimal corrosion inhibitor was screened from nineteen amino acid-derived Schiff bases using quantum chemical calculations and corrosion inhibition experiments. The selected Schiff base was immobilized on the Mg alloy surface via silane modification to construct a corrosion-resistant coating (Silane-loaded tryptophan Schiff base coating, defined as PMSB-X), whose performance was evaluated by electrochemical measurements and immersion tests. Subsequently, a carbon quantum dot-mediated nanodrug layer (NP-X) integrating sulfonated hyaluronic acid (S-HA) and Shenmai injection (SMI) was structured via ultrasonic atomization. The biological performance of the coating was systematically assessed through in vitro cell studies and in vivo animal experiments.

RESULTS: Tryptophan-derived Schiff base (SB-Trp) exhibited the highest corrosion inhibition efficiency (81.5%). The PMSB-5 coating constructed based on SB-Trp reduced the corrosion current density of Mg alloy to 9.96 × 10-9 A·cm-2, indicating significantly enhanced corrosion-inhibition capability and effective regulation of degradation kinetics. The NP-10 coating exhibited multiple biological functions, including reducing the hemolysis rate, inducing macrophage M2 polarization, inhibiting the proliferation of smooth muscle cells (SMCs) while promoting their contractile phenotype, and promoting the growth of human umbilical vein endothelial cells (HUVECs). Furthermore, the coating activated human cerebral microvascular endothelial cells (HCMECs), indicating pro-angiogenic potential. Animal experiments confirmed that the NP-10 coating simultaneously achieved degradation regulation and suppression of tissue hyperplasia and inflammation.

CONCLUSION: This bifunctional coating enables delayed Mg degradation, promotes endothelialization, and provides neurovascular protection, provides an important strategy for promoting the functional design of neurovascular treatment devices.