Study On Egcg-arginine Coating Deposited On316L Stainless Steel And Its Biocompatibility

Percutaneous coronary intervention (PCI) is used to treat blocked coronary arteries. But the implantation of stent may cause some problems. Bare-metal stents (BMS) were firstly used in PCI, yet often necessitated repair procedures due to in-stent restenosis. Drug-eluting stents (DES) were developed to address these problems as the stent-incorporated anti-proliferative drugs prevented restenosis. However late-stent thrombosis arose with the use of DES due to the polymer hypersensitivity and delayed re-endothelialization process. A potential solution for these problems is to develop a multifunctional stent which not only provides good hemocompatibility but also does well in promoting the re-endotheliazation process, inhibiting intima proliferation and inflammatory reaction. Recent researches mainly focus on building bionic platform on the stent surface. The main component of catechin in green tea,(-)-Epigallocatechin-3-gallate (EGCG), shows scavenging free radicals, anti-oxidation, anti-inflammation, anti-bacterial and inhibiting atherosclerosis. Especially, EGCG can inhibit smooth muscle cells (SMCs) proliferation, and protect endothelial from the injurious effects of reactive oxygen species. Therefore, coatings which contain EGCG is expected to achieve versatility of cardiovascular materials needed.In this work, three kinds of EGCG-ARG cross-linking coatings were obtained, respectively named EGCG/R-4/2, EGCG/R-2/2and EGCG/R-2/4, respectively. The chemical structure of the coatings was investigated by Fourier transform infrared spectroscopy (FT-IR). And the surface chemical composition of the coatings was measured by X-ray photoelectron spectroscopy (XPS). These results indicated that the EGCG-ARG cross-linking coatings were successfully deposited on316L SS surface, and the coatings remained the basic functional groups of EGCG and L-Arg like phenolic hydroxyl, quinone, carboxyl and so on. Besides, after coating formation, the surface presented more hydrophilic, the antioxidant ability evaluated by DPPH antioxidant assay indicated the highest ability to scavenge the free radical of the EGCG/R-4/2.Otherwise, the proliferation and viability of ECs and SMCs affected by EGCG with diverse concentrations was also investigated in this work. The results showed that the proliferation of SMCs was apparently inhibited when the concentration of EGCG was more than200mM, but the proliferation of ECs was enhanced at the same concentration. The EGCG-ARG cross-linking coatings were found beneficial to ECs proliferation, viability and migration, but reduced SMCs proliferation. The inhibitory effect of SMCs proliferation might be associated with the surface catechol contents.The EGCG-ARG coating contains kinds of functional groups like phenolic hydroxyl, quinol and carboxyl and so on. The BVLD is immobilized via condensation reaction of amino in coatings and carboxyl in BVLD after activation by EDC. The XPS confirmed the immobilization of BVLD on EGCG/R-4/2. QCM-D real time monitoring result showed that450ng/cm2of BVLD was bound to the EGCG/R-4/2surface. EGCG/R-4/2-BVLD apparently prolonged the activated partial thromboplastin time (aPTT), inhibited the activation of platelet. After culturing ECs on EGCG/R-4/2-BVLD, it enhanced ECs proliferation and spread.In general, the multifunctional EGCG-ARG cross-linking coatings have potential to modify cardiovascular implants. The coating shows anti-oxidation because of EGCG, inhibition of the smooth muscle cells, at the same time does not significantly inhibit endothelia cell proliferation. In addition, EGCG-ARG coatings can be used as a platform for the following biological molecules immobilization to be a potential way to surface modification of cardiovascular implants instrument.