Preparation And Performance Evaluation Of Silane Coating On Mg-Zn-Y-Nd Alloy Surface For Rapid Endothelialization

Magnesium alloy vascular stents have received more and more attention due to their good mechanical properties and degradability.People have developed various components of magnesium alloys for vascular stents according to different requirements.However,after the magnesium alloy vascular stent is implanted into the human body,the degradation rate is too fast,which leads to the premature loss of support.In addition,problems such as delayed endothelialization will cause restenosis in the stent,which severely limits the application of magnesium alloys in vascular stent materials.The Mg-Zn-Y-Nd alloy independently developed by our laboratory as a degradable magnesium alloy vascular stent material has good mechanical properties,but there are also problems of excessive degradation rate and potential stent restenosis.In order to reduce its degradation rate and accelerate its endothelialization,a series of surface modifications were carried out.First,the Mg-Zn-Y-Nd alloy was subjected to alkali thermal pretreatment to introduce hydroxyl groups on its surface,and then it was sequentially treated with 1,2-bis(triethoxysilyl)ethane(BTSE)and 3-aminopropyltriethoxysilane(APTES)to prepare a silane composite coating on the surface Introduce amino group.Finally,under the action of the activator,heparin sodium,REDV and anti-CD34 antibody were fixed to the silane coated surface in turn.In the characterization of materials,the process parameters of alkali thermal coating and silane composite coating are optimized by scanning electron microscope(SEM)and electrochemical test.The functional groups of each sample surface are detected by Fourier transform infrared spectroscopy(FTIR).The contact angle measuring instrument characterizes the wettability of each sample surface,and the amino group density changes in the process of immobilizing three biomolecules were studied by quantitative amino group experiment.In the biocompatibility characterization,the blood compatibility of each sample was evaluated by platelet adhesion,fibrinogen adhesion and denaturation,and hemolysis experiments.Through the relevant experiments of endothelial cells,macrophages and endothelial progenitor cells,the effects of three biomolecules on the growth behavior of the three cells were studied.The microscopic morphology was observed by SEM.It was found that when the alkali heat treatment temperature was 60?,the Na OH concentration was 3 mol/L,and the water bath heating time was 6 h,the prepared alkali thermal coating was dense and complete.The silane composite coating prepared by BTSE and APTES after 12 hours pre-hydrolysis was dense and complete.Electrochemical tests showed that,compared with Mg-Zn-Y-Nd,the corrosion current density of the alkali thermal coating has decreased by an order of magnitude,and the corrosion current density of the silane composite coating has decreased by two orders of magnitude.FTIR and amino quantitative experiment proved that the alkali thermal coating and the silane composite coating were successfully prepared,and the heparin sodium,REDV and anti-CD34 antibodies were successfully fixed.Water contact angle test showed that the final sample is more hydrophilic than Mg-Zn-Y-Nd.Blood compatibility experiments showed that compared with Mg-Zn-Y-Nd,the number of platelets adhered to the final sample surface is significantly reduced,the size of platelets is significantly reduced,the number of fibrinogen adhesion and degeneration is also significantly reduced,and the hemolysis rate is significantly reduced and less than the medical material standard.Endothelial cell apoptosis and NO release experiments showed that the fixation of three biomolecules promotes the adhesion and proliferation of endothelial cells and enhances the viability of endothelial cells.The adhesion experiment of macrophages showed that the surface of the magnesium alloy modified by the three molecules had a certain inhibitory effect on macrophages.Endothelial progenitor cell capture experiments showed that anti-CD34 antibody promotes the adhesion and proliferation of endothelial progenitor cells.