Today, the increasing incidence of cardiovascular disease has led to a significant increase in health in human societies. In this regard, the use of biodegradable cardiovascular stents based on magnesium to treat these diseases is increasing. The problem with using magnesium and its alloys is high corrosion rate, which reduces mechanical stability and activates the immune system. The aim of this study was to fabricate and characterize a bilayer composite coating of micro-arc oxidation-polyglycerol sebacate containing copper-chitosan nanoparticles on AZ91 magnesium-based alloy to improve corrosion behavior, blood compatibility and biocompatibility. In this regard, compaction polymerization of polyglycerol sebacate polymer was performed for coating on the micro-arc oxidation layer and then, the two-layer micro-arc oxidation-polyglycerol oxidation coating was fabricated on the AZ91 alloy. Polyglycerol sebacate coating was performed by electrospray method at 1, 3, 5 and 7 hours on the micro-arc oxidation layer and the optimal sample was obtained by X-ray, FTIR, roughness measurement, wettability, scanning electron microscopy, electrochemical tests, protein adsorption and resazurin assay. Then, copper-chitosan nanoparticles were dissolved in polymer solution with concentration of 1, 3 and 5 wt% and coated on micro-arc oxidation coating. In order to eva‎luate the polymer coatings containing nanoparticles, X-Ray, roughness measurement, wettability, scanning electron microscope, electrochemical tests, protein adsorption, cell adhesion, MTT test, platelet adhesion and nitric oxide release were performed. The results of infrared spectroscopy with Fourier transform showed that the synthesis of polyglycerol sebacate was successful. Subsequently, by coating the polyglycerol sebacate polymer by electrospray method on the micro-oxidation coating, this polymer was able to improve the wettability, roughness and corrosion behavior by modifying the surface and chemical properties of the surface. By applying a polymer coating on the surface of the micro-oxidation coating, the corrosion current density decreased from 0.36 μA/cm2 in MAO to 0.04 μA / cm2 in PGS7 sample. Then, by examining the biological properties of micro-arc oxidation-polyglycerol sebacate coating, the results showed that PGS3, PGS5 and PGS7 had good biocompatibility. The PGS7 sample was considered as the optimal sample to continue the research. Subsequently, by applying copper-chitosan nanoparticles to the polymer coating, the roughness and wettability were significantly changed, which was originated from nanoparticles. By studying the corrosion behavior, nanoparticles effected on the corrosion behavior and the corrosion current density decreased from 0.04 μA / cm2 in PGS7 sample to 0.02 μA / cm2 in Cu-5% sample. In the study of blood compatibility with the dopping of nanoparticles in polymer coatings, decrease in platelet adhesion was observed on the surfaces of polyglycerol sebacate polymer layer, which could be due to the local release of nitric oxide from the structure of copper-chitosan nanoparticles. However, the polyglycerol sebacate polymer has good hemocompatibility. By examining the biocompatibility with MTT assay, not only the nanoparticle-containing in coatings did not show any toxicity, but also the cells proliferated on days 3 and 5. Nitric oxide release from the copper-chitosan nitric oxide delivery system was investigated using nitric oxide release kits, which showed burst release. In conclusion, the bilayer micro-arc oxidation coating-polyglycerol sebacate containing copper-chitosan nanoparticles can have a high potential for vascular stents application.

مهشيد خرازيها، مسعود عطاپور

مهران نحوي، عبدالمجيد اسلامي