Study On The Dual-functional Endothelium Mimicking Coating On The Vascular Stent Based On In-situ Catalytic Release Of Nitric Oxide And VEGF Immobilization

Based on the fact that the mono-functional stents commonly used in clinical can't completely meet the clinical requirements of vascular stents,namely anti-coagulation,anti-inflammation,anti-hyperplasia,accelerating endothelium regeneration and curing the vascular pathological state of implanted site,a multi-functional endothelium mimicking coating was put forward in this study to solve the problems faced by the mono-functional clinical stents.Just as the natural endothelium does,poly-dopamine coating chelated with Cu²⁺?Cu^?-DA?endowed the vascular stent with in-situ catalytic release of nitric oxide?NO?when contacting with blood,which has the properties such as anti-coagulation,anti-inflammation,anti-hyperplasia etc.Furthermore,via the free functional group,namely phenolic hydroxyl/benzoquinonyl on the Cu^?-DA coating,endothelial cell growth factor?VEGF?covalently immobilized on vascular stent for the purpose of accelerating endothelium regeneration?VEGF/Cu^?-DA?.?1?Electron paramagnetic resonance?EPR?and matrix-assisted laser desorption ionization mass spectrometry?MALDI MS?were used to verify that the formation mechanism of Cu^?-DA framework was based on ion/molecule co-assembling process.The chemical composition and structure of the bionic coating were analyzed by Fourier transform infrared spectroscopy?FTIR?and X-ray photoelectron spectroscopy?XPS?.FTIR and XPS demonstrated the successful construction of muti-functional endothelium mimicking coating.?2?The hydrophilicity of the coating was measured by the water contact angle.The result showed that PDA?Cu^?-DA and VEGF/Cu^?-DA coatings significantly improved the hydrophilicity of 316L stainless steel.?3?The mass of VEGF grafted on the Cu^?-DA surface was measured using dissipative quartz crystal microbalance technique?QCM-D?.Approximately 400 ng/cm² of VEGF was immobilized on the surface of the coating after the dynamic analysis was finished.?4?Furthermore,the releasing rate of NO catalyzed by Cu^?-DA and VEGF/Cu^?-DA revealed that the graft of VEGF did not affect the catalytic ability of Cu²⁺,and the stability of releasing rate of NO catalyzed by VEGF/Cu^?-DA also showed that VEGF/Cu^?-DA still possessed very substantial releasing rate of NO after immersed in the NO donor for 30 days.?5?The results of the balloon dilatation experiment showed good flexibility of VEGF/Cu^?-DA coating,revealing its possibility as a scaffold modification material.?6?Adhesion?proliferation and migration assays of human umbilical vein endothelium cells?HUVECs?as well as adhesion?proliferation and migration assays of human umbilical vein smooth muscle cells?HUVSMCs?and competitive behavior of ECs and SMCs on the surface of the coating were used to assess the biocompatibility of muti-functional endometrium mimicking coating.The bionic coating selectively enhanced EC adhesion?proliferation and migration,and at the same time inhibited SMC adhesion?proliferation and migration.?7?Ex vivo perfusion experiments showed good anticoagulant properties of the endometrium mimicking coating.In vivo stent implantation showed that the endometrium mimicking coating can reconstruct a healthy ECs layer in vivo.All these provided methods and theoretical guidance for the study and construction of vascular stents with in-situ catalytic release of NO and VEGF immobilization.