| Nowadays, the percutaneous coronary intervention(PCI) is a main treatment for coronary artery disease. As a next-generation stent, Biodegradable stent, Completely Biodegradable stents(BDS) can not only realize temporary supporting wall, maintain vascular patency, effectively reduce the function of vascular risk acute occlusion after the stent implantation, they also can be used polymer coating as a drug carrier for the local delivery to reduce the risk of restenosis.Magnesium ion, is the fourth largest cation in the human body. Compared with other metals, magnesium alloy has a low density(1.74 g/cm3), higher specific strength and stiffness, rich in resources, good biocompatibility and biodegradable and other advantages. But the magnesium and its alloys have some disadvantages in the human body physiological environment rich in Cl ions, such as the poor corrosion resistance, the fast degradation rate, the big brittleness, the poor plastic deformation capacity. Hence, surface treatment of magnesium stents to improve the application of magnesium-based materials provides a new approach for the application of magnesium alloy stent in clinic. Zartner and other researchers have successfully put the magnesium metal stents into a premature left pulmonary artery for the first time, after clinical observation, the early results of the patient are satisfactory, therefore magnesium is expected to become a new material of the BDS. Therefore, the controlling degradation rate of magnesium-based materials is a vital issue.Poly(beta hydroxy butyric acid ester(PHB) is a kind of natural macromolecule polymer, stored in the cell under the condition of unbalanced microbes grow, and widely exists in many prokaryotes, which has been widely used in the field of drug release and tissue engineering. PHB, due to its superior biocompatibility and biodegradability, has been gotten more and more attention in the field of medical. In the natural environment, PHB can be generated CO2 and H2 O by the microbial degradation and release energy. While in vivo environment, its degradation mainly depends on fluid infiltration sleep solution, which makes ester linkage fracture passive, In addition the body has trace of esterase page, which can destroy the ester bond, and the erosion of the macrophages also has a promoting effect to the degradation of PHB. Therefore, the protective effect of PHB can reduce the degradation rate of magnesium alloy, achieving the requirement of stent materials.â‘ The polymer coated magnesium alloys were characterized by infrared spectrum analysis and static water Tentacles. Experimental results confirmed that the hot water after the pretreatment of magnesium alloy materials and polymer coating of magnesium alloy material is rather distinct from hydrophilic property. Static water contact angle of magnesium alloy materials before and after polymer coating have significant differences. After polymer coating of magnesium alloy m aterials compared with bare magnesium alloy materials has significant differences in hydrophilic and hydrophobic, this will help to slow the intrusion of water.â‘¡ Through vitro experiment to test the different corrosion rate of magnesium alloy material before and after polymer coating. Static corrosion experiments shows that, compared with bare magnesium alloy materials, the mag nesium alloy material after the polymer coating, shows a lower weight loss and magnesium ions concentration, and assume a smaller change extent. Compared with the magnesium alloy material without polymer coating, the magnesium alloy material with the PHB coating shows a smaller variations in p H, having a p H below 8.0 for 15 days. Electrochemical polarization curve of the experiment shows that after polymer coating, the magnesium alloy material presents a significantly lower natural corrosion current and a higher natural corrosion potential. These results powerful confirm that the resistance of Magnesium alloy material after PHB coating has been enhanced obviously after polymer coating corrosion.â‘¢ blood compatibility result shows that the hemolysis rate of the magnesium alloy material with polymer coating of is 4.19%, less than 5%, conform to the requirements of medical material. However, the hemolysis rate of the magnesium alloy material without coating is as high as 37.61%, which means that there will be a terrible hemolysis phenomenon. The significant difference of magnesium ions concentration in leaching solution also shows that the polymer coating on magnesium alloy material has certain protective effect. Cell compatibility results shows that the magnesium alloy material with the polymer coating is conducive to cell proliferation.NO determination results show that,compared with the normal cells, there were NO significant difference in the leaching solution cultured cells of magnesium alloy material both with coating and without coating. Total antioxidant capacity results show that, the leaching solution of cultured cells of magnesium alloy material without coating, have a significant total antioxidant capacity difference, compared to normal cells. And, the leaching solution of cultured cells of magnesium alloy material with PHB coating, have a more significant total antioxidant capacity difference, compared to normal cells. This results shows that the magnesium alloy material with PHB coating is conducive to improve the total antioxidant capacity. It shows that, after PHB coating, the biocompatibility of magnesium alloy material get obvious improvement. |
PDF Full Text Request