Aptamer Surface-modified Medical Stainless Steel And It’s-endothelial Progenitor Cell Capture Capability

The problems of thrombosis and the restenosis are the main limitations for coronary artery stents implantation. Because stent implantation procedure and distraction can cause serious damage to the blood vessel wall, and thus induce excessive proliferation of smooth muscle cells, in-stent restenosis may occur. Meanwhile, the site of vascular injury may release large amounts of tissue factor-induced thrombosis, and ultimately form thrombus. Incomplete endothelialization is a major cause of thrombosis and intimal hyperplasia. A monolayer of endothelial cells (ECs) has a natural anticoagulant capacity. Rapid endothelialization of the implant surface can effectively reduce thrombosis, prevent implantation restenosis. Endothelial progenitor cells (EPCs) with high proliferative potential is considered as an important element of vascular injury response, which can repair andform new blood vessels. The Dopa-PEI coating was successfully deposited on the surface of biomedical stainless steel based on the auto-polymerization of dopamine and the reaction between dopamine and polyethylenimine. Furthermore, the aptamer molecules were assembled on the Dopa-PEI coating (DOPA-PEI+A) and the endothelial progenitor cell-capturing coating was constructed.In this study, compared to auto-polymerization coating of dopamine, polyethyleneimine was introduced into Dopa-PEI coating, which can enhance amino density of thecoating surface and construct an amine-rich surface with large numbers of positive charges. And the DNA aptamers was immobilized on the surface by electrostatic interaction. The surface physical and chemical properties of the amino-rich film and the aptamer introduced-surfaces were studied by attenuated total reflection Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), Zeta potential, fluorescence microscopy, quartz crystal microbalance and dissipation (QCM-D), and water contact angle (WCA). In vitro cell culture and dynamic endothelial progenitor cell capturing experiments were carried out to evaluate the influence of the functional coating on endothelial cells (ECs) and smooth muscle cell (SMCs)adhesion and proliferation behavior, and the capturing capability of endothelial progenitor cells on dynamic condition.The results of XPS and amine fluorescence staining indicated that dopamine and polyethylenimine formed crosslinking coating on biomedical stainless steel via Michael addition and Schiff base reaction, and the amino-rich surfaces was successfully constructed. Zeta potential showed that surface potential of Dopa-PEI in pH< 7 was positively charged. ATR-FTIR, fluorescence-staining and QCM test proved that aptamers successfully assembled on the crosslinking coating surface, and the surface density of aptamerswas 298.4 ng / cm2.In vitro ECs and SMCs evaluations showed that the Dopa-PEI coating could inhibit adhesion and proliferation of SMCs and ECs. This is because that there are large numbers of amine groups on the coating surface. But after aptamers were immobilized on the surface, the inhibition effect of ECs and SMCs was reduced. EPC-capturingtests showed that the DOPA-PEI+A could capture EPC and promote the adhesion under the dynamic condition.In this paper, aptamer molecules immobilized-Dopa-PEI coating can effectively capture EPCs under the dynamic condition, and provided a potential method for constructing endothelial progenitor cell-capturing surface.