生物可降解支架的制备与初步评价

发布时间：2018-04-15 18:06

本文选题：生物可降解支架 + 体内　；参考：《上海交通大学》2014年硕士论文

【摘要】：支架在治疗生理性官腔如血管、食道、胆道、尿道的闭塞或狭窄的方面起着越来越重要的作用，这是由于支架具有支撑管壁的作用，能够维持腔道的畅通。目前，临床上使用的支架主要是由塑料或金属制备而成。塑料支架和金属支架具有机械支撑作用强的优点，能够维持腔道的长期通畅，这使他们适用于不同类型的阻塞性病变，包括恶性梗阻。但是，它们也有缺点，如由于上皮细胞增生将导致支架难以从体内取出，因而不适合治疗良性梗阻。近年来，生物可降解的支架已倍受关注，有文献报道生物可降解的支架不太可能引起上皮细胞增殖和形成生物薄膜，最重要的是可以自行降解，不需要取出。因此，生物可降解支架有许多功能优于金属支架，是一种理想的在体内起短暂支撑作用的支架。本论文采用生物可降解纤维通过编织和激光切割两种方法制备了生物可降解支架，并对生物可降解编织支架进行了体内降解行为和力学性能的评价，对激光切割支架进行了体外降解行为和力学性能的评价。制备了基于生物完全可降解高分子材料聚乙交酯丙交酯（PGLA,GA/LA摩尔比=90/10）的完全生物可降解编织支架，研究了支架在SD大鼠皮下的体内降解情况。通过采用测失重率、吸水率，扫描电子显微镜，差示扫描量热法，核磁实验，傅里叶红外变换等测试手段，对支架的体内降解过程的形态和性能进行了研究。结果表明，用拉伸倍数为5的PGLA纤维编织的支架在植入SD大鼠皮下后降解最慢，质量损失、吸水率、结晶度、化学成分和径向压缩力的变化最慢。纤维的拉伸倍数会影响支架的力学性能和热力学性能的变化，为在体内起到短暂支撑作用的支架的深入研究提供了基础，这种新的手工编织的支架具有支撑良性狭窄的潜在应用。采用激光切割的方法制备了具有不同的支架管壁厚度和不同的支架管壁孔的大小的聚乳酸支架PLA-1，PLA-2，PLA-3和聚几内酯支架PCL-1，PCL-2五种生物可降解支架，分别在pH7.4和6.5的磷酸缓冲溶液（PBS）中进行22天的体外降解实验，通过采用失重率、吸水率、GPC、核磁实验、扫描电镜考察了支架的体外降解情况，并通过测径向压缩力的大小探索了支架的结构设计对其径向压缩性能的影响。结果表明，PLA支架和PCL支架在PBS溶液中放置22天的质量损失并不明显，分子量变小，结构没有什么变化。通过扫描电镜观察到支架的表面出现少量的空洞。对比不同的支架设计参数和降解介质的pH值，，发现pH在降解初期对支架的质量损失的作用并不明显，但是pH6.5的PBS溶液中支架的分子量下降的百分比更大。支架的力学性能与支架材料本身有关系，与支架的管壁的厚度成正相关关系，与支架管壁的孔的大小成负相关的关系。因此，可以通过改变支架的结构参数，使得支架的力学性能符合实际应用。
[Abstract]:Stent plays a more and more important role in the treatment of physiologic official cavity such as blood vessel, esophagus, bile duct, urethra occlusion or stricture, because the stent has the function of supporting the wall and maintaining the smooth flow of the lumen.At present, the stents used in clinical use are mainly made of plastic or metal.Plastic and metal scaffolds have the advantages of strong mechanical support and can maintain the long-term patency of the lumen, which makes them suitable for different types of obstructive diseases, including malignant obstruction.However, they also have disadvantages, such as epithelial cell proliferation will make it difficult to remove the stent from the body, so it is not suitable for the treatment of benign obstruction.In recent years, biodegradable scaffolds have attracted much attention. It has been reported that biodegradable scaffolds are unlikely to cause epithelial cell proliferation and biofilm formation. The most important thing is that biodegradable scaffolds are self-degradable and do not need to be removed.Therefore, biodegradable scaffolds have many functions better than metal scaffolds, which is an ideal scaffold for short-term support in vivo.In this paper, biodegradable scaffolds were prepared by braiding and laser cutting with biodegradable fibers. The biodegradable scaffolds were evaluated for their in vivo degradation behavior and mechanical properties.The degradation behavior and mechanical properties of laser cutting scaffolds in vitro were evaluated.A completely biodegradable braided scaffold was prepared based on the biodegradable polymer material PGLA / LA molar ratio of 90 / 10. The degradation of the scaffold in SD rats was studied in vivo.The morphology and properties of the in vivo degradation process of the scaffold were studied by means of weightlessness, water absorption, scanning electron microscope, differential scanning calorimetry, nuclear magnetic experiment and Fourier transform infrared transform (FTIR).The results showed that the scaffold braided with PGLA fiber with tensile ratio of 5 was the slowest degradation, mass loss, water absorption, crystallinity, chemical composition and radial compression force of SD rats.The tensile ratio of the fiber will affect the mechanical and thermodynamic properties of the scaffold, which provides the basis for further study of the scaffold, which plays a temporary supporting role in the body.This new hand-woven scaffold has potential applications for supporting benign strictures.Five biodegradable scaffolds, PLA-1, PLA-2PLA-3 and PCL-1 / PCL-2, which have different wall thickness and pore size, were fabricated by laser cutting.In vitro degradation experiments were carried out in pH7.4 and 6.5 phosphoric acid buffer solution for 22 days. The degradation of the scaffold was investigated by means of mass loss rate, water absorption rate and nuclear magnetic resonance (NMR).The influence of the structure design of the support on its radial compression performance was explored by measuring the radial compression force.The results showed that the mass loss of the PCL scaffolds and the PLA scaffolds in PBS solution for 22 days was not obvious, the molecular weight became smaller and the structure did not change.A small number of holes were observed on the surface of the scaffold by SEM.Comparing with different scaffold design parameters and the pH value of degradation medium, it was found that pH had little effect on the mass loss of the scaffold at the initial stage of degradation, but the molecular weight of the scaffold decreased more in the PBS solution of pH6.5.The mechanical properties of the scaffold are related to the material itself, to the thickness of the wall of the scaffold, and negatively to the size of the hole in the wall of the scaffold.Therefore, the mechanical properties of the scaffold can be adapted to the practical application by changing the structural parameters of the scaffold.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R318.08

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