可降解聚合物多孔支架的制备及其细胞相容性研究

发布时间：2018-02-05 01:51

本文关键词： 可降解聚合物多孔支架制备细胞相容性组织工程　出处：《华南理工大学》2015年博士论文　论文类型：学位论文

【摘要】：可降解聚合物多孔支架是组织工程领域的重要研究方向之一,在组织工程中起着关键的作用。人工合成可降解聚合物具有良好的可调控性,在组织工程领域中具有广泛的应用。但是,人工合成聚合物支架的亲水性差且缺乏可供细胞粘附的结合位点,导致细胞在该类支架上的生长受到了极大的限制。因此,如何制备出细胞相容性良好的可降解多孔支架是目前该领域的研究热点和难点。静电纺丝法制备出的纤维支架可以很好的模拟仿生细胞外基质,本博士论文对如何改进纤维支架的细胞相容性做了深入的研究和探讨。首先基于静电纺丝法,结合溶液共混和冷冻干燥技术制备出了聚碳酸亚丙酯(PPC)与天然高分子明胶(gelatin)的纳米级复合纤维支架、热塑性聚氨酯和氧化石墨烯(GO)复合纤维小直径血管支架和具有PPC微米级纤维/壳聚糖(chitosan)纳米级纤维并存的层次结构的纤维支架。研究发现当gelatin在纺丝液中含量高于10%时,gelatin与PPC在纺丝过程中会发生严重相分离导致纺丝液喷溅、纤维粘接等现象的发生。加入微量醋酸可改善gelatin与PPC的相容性,使得混合液的纺丝过程顺利进行得到尺寸均匀的纤维,且加入的gelatin极大的改善了复合纤维支架的亲水性及细胞相容性;通过自主搭建的旋转型收集装置制备出具有不同GO和PEI含量的TPU/GO,PCL/PEI小直径血管支架,探讨GO和PEI对复合纤维支架的结构形态、亲水性能的影响,并以人体血管内皮细胞为细胞模型,研究了GO和PEI的含量对细胞的生长形态的影响,发现了低含量的GO和PEI对细胞的生长有促进作用,而高含量的GO和PEI会导致细胞的死亡;调节溶剂的组成和搭建平行板收集装置制备出了高度取向的PPC微米纤维支架,通过壳聚糖溶液浸润和冷冻干燥后处理,在PPC微米纤维支架内引入chitosan纳米纤维,制备出的支架不仅具有微米级纤维和纳米级纤维的层次结构,而且含有生物相容性良好的chitosan,细胞培养结果表明该微纳纤维复合结构为细胞的生长提供了适宜的环境。其次,在静电纺丝的基础上,采用聚己内酯(PCL)纳米纤维作为shish来诱导在稀溶液的聚合物分子在其表面自发结晶形成周期性排列的晶片即kebab,制备出具有串晶结构的纤维支架来改变支架的微观拓扑结构,并采用天然聚合物修饰串晶纤维支架以达到在结构上和功能上能够仿生细胞外基质中胶原纤维的目的。分别研究了shish的组成,kebab溶液的组成对形成的串晶结构的影响。研究发现:采用聚己内酯(PCL)/纳米级羟基磷灰石(n HA)复合纤维作为shish制备出的串晶结构具有良好的仿生矿物化性能且有利于人体骨肉瘤细胞(MG63)的生长,且使得纤维支架的力学强度得到改善;与77%的醋酸相比,使用PCL溶解度更低的乙酸戊酯作为溶剂配制的稀溶液有利于在PCL纳米纤维上形成规整的kebab;采用化学接枝的方法在PCL串晶纤维支架表面接枝生物相容性好的基质胶(matrigel)可改善纤维支架的亲水性和细胞相容性。针对在研究中发现的溶液共混和化学接枝法的缺点和不足,提出chitosan-PCL共聚物在PCL纳米纤维表面结晶来制备支架的新方法,在结晶过程中,共聚物中的PCL端会在纺丝纤维表面自发结晶形成周期性排列的晶片,而共聚物中的壳聚糖则由于PCL纤维的排斥作用而被暴露在外。采用该思路制备出的纤维支架既使得支架具有串晶结构这一独特的微观拓扑形态,又使得复合纤维支架富含壳聚糖单元来提供细胞的结合位点。研究发现:采用该设计思路制备出的支架具有良好的亲水性、仿生矿物化性能、细胞相容性以及优良的成骨能力。最后,为解决静电纺丝法制备出的纤维支架规整性不足且难以制备成特定形状的多孔支架的缺陷,并且采用简单的热致相分离法经常涉及到有毒溶剂的使用的问题,提出了一种将挤出发泡法、沥滤法以及冷冻干燥法相结合、并通过材料体系和工艺条件的调控制备获得了具有双峰泡孔结构的富含壳聚糖纳米纤维的PCL三维多孔支架的新方法,为批量化生产细胞相溶性好、泡孔率高、内部连通性好的三维多孔支架提供新思路。
[Abstract]:Biodegradable polymer porous scaffolds is one of the important research direction in the field of tissue engineering, plays a key role in tissue engineering. Synthetic biodegradable polymer has good regulation performance, is widely used in the field of tissue engineering. However, synthetic polymer scaffolds poor hydrophilicity and lack of binding sites for cell adhesion, leading to the growth of cells in the scaffold has been extremely limited. Therefore, how to prepare a good biocompatibility of biodegradable porous scaffolds is a hot and difficult topic in the field of fibrous scaffolds prepared by electrostatic spinning can simulate the biomimetic extracellular matrix is very good, the doctoral dissertation on how to improve the fiber scaffold biocompatibility to do in-depth research and discussion. Firstly, based on the combination of electrospinning, solution blending and freeze drying technology for preparing poly out carbon Acid propylene (PPC) gelatin and natural polymers (gelatin) nano composite fiber scaffolds, thermoplastic polyurethane and graphene oxide (GO) composite fibers of small diameter vascular stent and a PPC micron fiber / chitosan (chitosan) fiber scaffold hierarchy of nano fiber coexist. The study found that when gelatin in the spinning solution content is higher than 10%, gelatin and PPC will cause serious result in separation of spinning liquid splash in the spinning process, fiber bonding and other phenomena. Adding trace acetic acid can improve the compatibility with PPC gelatin, the spinning process of mixture of smooth uniform size of the fiber, and the addition of gelatin greatly to improve the hydrophilicity and cell compatibility of the composite fiber scaffolds; by rotating the type self built collection device were prepared with different GO and PEI contents of TPU/GO, PCL/PEI small diameter stent, on G The structure and morphology of O and PEI on the composite fiber scaffolds, effect of hydrophilic properties, and to human endothelial cells as the cell model, the influence on the growth morphology of GO and PEI content of cells, found the role of low content of GO and PEI on cell growth, and high content of GO and PEI can cause cell death; composition and regulation of solvent to build parallel plate collection device fabricated PPC micron fiber scaffold highly oriented, through the infiltration of chitosan solution and freeze-drying postprocessing, the introduction of chitosan nano fiber in PPC micron fiber stent, stent structure prepared not only has the micron fiber and the nano fiber, and with good biocompatibility of chitosan, cell culture results showed that the micro nano fiber composite structure for cell growth and provide a suitable environment. Secondly, based on electrospinning, using Polycaprolactone (PCL) nanofiber as shish induced polymer molecules in dilute solution on the surface of the wafer to form spontaneous crystallization of periodic arrays of kebab, prepared with micro topology on fiber scaffolds to change the crystal structure of stents, and the use of natural polymer modified shish-kebab fibrous scaffolds to collagen fibers the purpose of the biomimetic extracellular matrix in structure and function. The composition of shish were used to investigate effects of components of kebab solution on the formation of shish kebab structure. The study found: with polycaprolactone (PCL) / nano hydroxyapatite (n HA) on crystal structure of composite fiber as shish prepared has the good performance of the biomimetic mineralization and is beneficial to human osteosarcoma cells (MG63) growth, and the mechanical strength of fiber scaffold is improved; compared with 77% acetic acid and amyl acetate with lower solubility of PCL As the solvent dilute solution is conducive to the formation of regular kebab in PCL nano fiber; using the method of chemical grafting on compatibility matrix with good crystal fiber graft stent surface biological in PCL (Matrigel) can improve the fiber scaffold hydrophilicity and biocompatibility. The solution is found in the research of chemical blending grafting of the shortcomings and deficiencies, this paper presents a new method of chitosan-PCL copolymer in surface crystallization of PCL nanofibers scaffolds, in the crystallization process, the copolymer PCL end will form a periodic arrangement of the wafer in the spinning fiber surface spontaneous crystallization, while the copolymer of chitosan is due to repulsion of PCL fiber was exposed outside. Not only makes the stent has a unique crystal structure on micro topology using the fiber scaffold prepared by the idea of system, and make the composite fibrous scaffold containing chitosan unit to provide fine The cell binding sites. The study found: with good hydrophilicity with stent prepared the design ideas for the mineral properties of bionic, biocompatibility and excellent osteogenic ability. Finally, the defect for regular fiber scaffold prepared by electrospinning the solution is insufficient and difficult to prepared porous support to a specific shape and, by a simple heat often involves the use of toxic solvent induced phase separation problem, puts forward a method of combining extrusion foaming, leaching and freeze drying method, and control system through the material and process conditions were obtained a new method of PCL scaffolds with rich chitosan nanoparticles Shuangfeng fiber foam structure for the mass production of cells, good intermiscibility, bubble rate is high, the internal porous scaffold with good connectivity to provide new ideas.

【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ340.64

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