Surface Preparation and Cytocompatibility of Three-Dimensional Printed Fully Degraded Coronary Stents Using the Plasma Polymerization Technology

Abstract

Vascular stents made based on three-dimensional (3D) printing technology for interventional therapy have become one of the more common clinical means to treat patients with severe coronary heart disease (CHD). However, the biocompatibility of stent surface needs to be further improved. Over the past years, many researchers have adopted surface modification technology to improve the cytocompatibility of vascular stents. In this work, plasma polymerization (PP) technology was employed to introduce the allylamine (AA) and nitrogen with different concentrations as auxiliary gases. After ionization, fragmentation, and recombination, the surface of the stent was deposited to form amine-rich coatings (AMMak membrane and AMMak-N membrane). The composition and surface morphology of the coating were analyzed by physical characterization (infrared, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA), etc.). In addition, the cytocompatibility of the coating before and after modification was evaluated by using the endothelial cells (EC) implantation test. The biodegradable substrate (MgZnMn, Fe) was employed to deposit the amine-rich coatings and evaluate their cytocompatibility. The results told that the polymeric coating had a higher concentration of amine group when the nitrogen flow rate was at 5 sccm, and the coating was conductive to the adhesion and proliferation of ECs by adsorbing proteins. After the introduction of biodegradable substrate, the amino group on the coating surface further improved the cytocompatibility of the material. The PP technology can be applied to prepare a relatively dense PP coating, which can be further precipitated and solvent-free deposition. Therefore, it is very suitable for modifying the surface of degradable vascular stent materials.