Preparation And Performance Study Of PGA-PCL Composite Coating On Magnesium Alloy For Vascular Stent

The degradable vascular stent will gradually disappear after completion of human service,avoiding the inflammatory reaction caused by the long-term retention of the non-degradable stent in the body,and has become a current research hotspot.Among them,magnesium alloy has become the most promising scaffold material due to its good mechanical properties and good biocompatibility,but the excessively fast degradation rate makes the magnesium alloy scaffold lose its mechanical properties too fast during the implantation process,which seriously restricts Its clinical application.Surface modification can reduce the degradation rate of magnesium alloy while achieving rapid endothelialization,which is an effective way to solve the current problems facing magnesium alloy.In this paper,a polyglycolide(PGA)coating was successfully prepared on the surface of magnesium alloy by the constant current method.The microstructure and properties of the coating were analyzed by scanning electron microscopy(SEM)and electrochemical testing to optimize the coating preparation.Best process parameters.On this basis,combined with the characteristics of the dendrimer structure of the electropolymerized PGA coating and the advantages of strong hydrophilicity and fast degradation,the PCL coating was dip coated to prepare a PGA-PCL composite coating with adjustable degradation and drug loading of different ingredients Coating,through the hemolysis rate and platelet adhesion experiment to study the blood compatibility of the drug-carrying system,through the endothelial cell adhesion and proliferation experiments to explore its cell compatibility.The FTIR,XRD and XPS experimental results show that the PGA coating was successfully prepared on the magnesium alloy surface.When the current is 1.2 m A,the concentration is 0.5 mol/L,and the time is 1800 s,the prepared PGA coating is uniform and complete,the surface C and O elements account for more than 95%;the self-corrosion potential is 98 m V higher than that of magnesium alloys,and the corrosion current density is reduced 73.2%.Dip-coating PCL can effectively close the structural pores of the PGA coating,improve the corrosion resistance and improve the composition of the coating,and regulate the degradation of the coating.FTIR and XRD test results show that the PGA-PCL composite coating was successfully prepared.The cross-cut test shows that the bonding strength between the composite coating and the substrate is greatly improved compared to the PCL coating.Electrochemical tests show that the composite coating has an increased self-corrosion potential of 260 m V compared to magnesium alloys,and the corrosion current density has decreased from 410?A/cm~2to 9.1?A/cm~2.Coating micromorphology,sample weight loss test and p H test results show that the addition of PGA in PGA-PCL composite coating can accelerate the degradation of the coating.Different simvastatin(SIM)drug-loaded coatings were prepared on the magnesium alloy surface by dip coating,and their hemolysis rate was less than 5%,which met the requirements of biological safety;the results of cell experiments showed that the addition of SIM can inhibit platelet aggregation and promote Endothelial cell adhesion and proliferation;PGA-PCL-SIM coating has better blood compatibility and cell compatibility than PCL-SIM coating.