4D打印负泊松比聚乳酸心脏支架的体外性能研究

Study on In Vitro Performance of 4D Printed Polylactic Acid Vascular Stents with Negative Poisson′s Ratio

冠心病等心血管疾病的发病率逐年提高,血管支架使用率大幅提升.聚乳酸等形状记忆聚合物生物相容性较好、具有一定生物降解特性,可以用于制备新型心脏支架.心脏支架需要收缩时体积尽可能小,且膨胀时足以撑开堵塞的血管,因此需要具有负泊松比特性.本文基于聚乳酸的力学和形状记忆性能,设计了不同截面胞数的凹六边形负泊松比心脏支架模型,使用4D打印熔融沉积成型技术对其制备,并对血管支架模型的力学性能、形状记忆性能及血管支撑性能等进行测试,分析了支架的不同构型对支架体外性能的影响.同时,进行了有限元数值模拟,弹性模量和泊松比计算结果与实验相吻合.本文提出的模型对于通过4D打印的方式构建在临床上可用的新型血管支架具有重要参考价值.

The incidence of cardiovascular diseases such as coronary heart disease has increased year by year,giving rise to the significant increase of the utilization of vascular stents.Shape memory polymers such as polylactic acid have good biocompatibility and certain biodegradation properties,and can be used to prepare new heart stents.Heart stents need to be as small as possible when contracted and large enough to support the blocked blood vessels when expanded,therefore they show a characteristic of negative Poisson's ratio(NPR).In this paper,based on the mechanical and shape memory properties of the polylactic acid,a heart stent model of NPR concave hexagons with different cross section cell numbers is designed,and the specimens are prepared using the 4D printing technology of melt deposition molding.The mechanical properties,shape memory properties and vascular support properties of the vascular stent model are tested.The influences of different stent configurations on the in vitro performance of the stent are analyzed.Meanwhile,FEM simulations are performed and the results of elastic modulus and Piosson's ratio agree with the experimental data.The model proposed in this paper is of significant reference value in constructing new types of 4D printed vascular stents which can be used in clinic practice.