Fabrication And Study Of New Type Hydrophilic Coronary Stent

Fabrication and Study of New Type Hydrophilic Coronary StentAt present, clinical coronary stents are usually covered by some antiproliferative medicine, such as Rapamycin, Paclitaxel and so on to be a slow-release system in body. But drugs on stents make delayed endothelialization and activate all kinds of cells release cytokine to cause blood clotting. Moreover, it needs a long time to release drugs from stents into blood. So for preventing thrombosis with stents, patients have to take anticoagulants in long term. In order to enhance anticoagulant effect and biocompatibility, researchers are working on changing physical and chemical characters of stents on surface by methods of chemical reaction, graft polymer, spray coating process, electrodeposit, et al.Our study mainly utilizated advanced chemical technology to make stainless steel surface hydroxylation and silanization. After responding with different silane coupling agents, different hydrophilic groups of the silane-derived materials are fabricated. Biocompatibility and risks of thrombosis of different degree of hydrophilic-coated coronary stents were tested by experiments in vivo and in vitro. The results of our study provide important theoretical and experimental bases for new coronary stents.The investigation indicated:1. By hydroxylation and silanization, different hydrophilic groups of the silane-derived materials are fabricated.2. The ability of absorbing platelets is not dependent in degree of hydrophilic materials. N-(2-aminoethyl)-3-Ammonia propyl trimethoxysilane stents absorb less platelets on its surface than other hydrophilic materials.3. The haematolysis rate of all hydrophilic materials are all less than 5% and have little toxicity to red blood cells(RBC). N-(2-aminoethyl)-3-Ammonia propyl trimethoxysilane stent and 3-aminopropyl triethoxysilane (KH550) have similar least toxicity to RBC and are better than other hydrophilic materials.4. Assay of cytotoxicity showed that N-(2-aminoethyl)-3 Ammonia propyl trimethoxysilane stent and 3-aminopropyl triethoxysilane (KH550) have little toxicity, which belong to 0 grade:316L stainless steel belongs to 1 grade; the other three materials belong to 2 grade.5. Endothelial cells covered well and less thrombsis and angiostegnosis with N-(2-aminoethyl)-3-Ammoniapropyl trimethoxysilane stent after coronary stent implantation for one month. It has better bioactivity than others.In this study.we utilizate advanced chemical technology to fabricate different hydrophilic stents. Results of experiments show that biocompatibility of different stents is not directly with their hydrophilic degree. N-(2-aminoethyl)-3-Ammonia propyl trimethoxysilane stent has better biocompatibility with other hydrophilic stents, which may be developed for a novel coronary stent. However, many problems still need to be solved. There is a long way to go before practical use in clinic.