Preparation Of Biological Functional Magnetic Nanoparticles And Study On The Effect Of Guiding Endothelial Progenitor Cells In Vitro

Because of its high incidence and high mortality rates, coronary atherosclerotic heart disease has become a serious threat to human life and health and has bad impact on quality of life. Currently, in addition to basic treatment of drugs and cardiovascular bypass surgery, interventional treatment of cardiovascular stents has become another effective means of treating coronary artery disease. After Cardiovascular stent is implanted in patients, restenosis in-stent and late thrombosis may occur, which seriously affect the safety of the treatment and the long-term effect.. A complete intimal layer of normal physiological function forms in the implantation site of the stent, which is considered to be a feasible solution to the above problems.Endothelial progenitor cells are a class of pluripotent stem cells originating in the bone marrow mesenchymal, with a characteristic of migration in the blood. It has a strong proliferative capacity and can differentiate into endothelial cells and repair damage in the vessel wall. Capturing progenitor cells to the stent surface has become a research hotspot. Biological molecules identifying endothelial progenitor cells are fixed in the surface of the endothelial progenitor cell capture stent to capture the endothelial progenitor cells. However, because of the weak specificity of binding between endothelial progenitor cells and biological molecules, the small number of progenitor blood cells and other factors, the number of endothelial progenitor cells and process of capturing the stent surface are limited. In this study, magnetic nanoparticles modified with aptamer were constructed, which can specifically bind to endothelial progenitor cell and enriched in the surface of the stent under the guidance of a magnetic field, in order to achieve the purpose of rapid endothelialization.Ferroferric oxide magnetic nanoparticles wrapped with L-DOPA were prepared by chemical coprecipitation method. After the nanoparticles were synthesized, EDC was used to activate the carboxyl group of L-DOPA, which forms amide bond with specific amino on the aptamer by dehydration condensation reaction. Magnetic nanoparticles were surface modified with aptamer and L-DOPA. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), nanoparticle size analysis (SEM), magnetic measurement (VSM) and other testing methods were used to detect the magnetic nanoparticles in different stages. The endothelial cells were cocultured with the surface modified magnetic nanoparticles to evaluate cell compatibility and the combination effect of nanoparticles on endothelial progenitor cells in a short period of time. Directional guide of the surface modified magnetic nanoparticles to EPCs was evaluated under an applied magnetic field and simulated dynamic blood flow condition.The results showed that the prepared magnetic nanoparticles have good magnetic response, good cell compatibility within a certain range of the nanoparticle concentrations. The surface modified nanoparticles can combine with endothelial progenitor cells effectively in a short time, and those nanoparticles combined EPCs can be directional guided on to a stent surface under the magnetic field in the dynamic flow environment.