【作者】 唐勇红；

【导师】 杨庆；

【作者基本信息】 东华大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 组织工程支架是组织工程研究的重要内容之一。目前,静电纺丝已广泛应用于组织工程支架的研究。本文采用静电纺丝技术作为制备支架材料的方法,优化纺丝工艺条件,制备出了仿细胞外基质结构的多孔网状组织工程支架材料。所制备的电纺纳米纤维支架材料具有孔隙率高、比表面积大、均一性好、长径比大等优点,能够从纳米尺度上模仿天然胞外基质,可作为细胞生长的多孔支架,促进细胞的迁移和增殖。本文选取聚乳酸、聚己内酯、聚羟基丁酸戊酸共聚酯、透明质酸为支架材料。利用静电纺丝、等离子体改性等技术制备了复合纳米支架。较为系统地测试了其用于组织工程支架的各种性能:通过扫描电镜(SEM)、差热分析(DSC)、动态力学性能(DMA)、宽角X射线(WAXD)和接触角对支架结构与形态、力学性能、结晶性能及亲水性进行了表征;通过加酶在缓冲溶液中的降解,研究了其降解性能;将体外培养的真皮成纤维细胞接种至材料表面,用扫描电镜观察成纤细胞在材料表面的生长情况。具体研究结果如下:1.以二氯甲烷/DMF(60:40)为溶剂,制备了PHBV、PLLA、PHBV/PLLA的电纺超细纤维;同时平行讨论了以氯仿/DMF(60:40)为溶剂制备PLLA、PCL、PLLA/PCL电纺纤维膜的工艺过程。研究发现:以氯仿/DMF(60:40)、二氯甲烷/DMF(60:40)适合做PLLA、PHBV、PCL及其混合物的溶剂,所制备的纤维直径均一且呈相互连通的多孔网状结构。2.电纺过程中,纤维的高分子链产生一定的排列和高度取向,但由于纤维的固化速度快,高分子链来不及进行规整排列而形成结晶,因此,DSC和XRD的结果都显示,PLLA、PCL静电纺纤维毡的结晶度要比相应的膜低。对于PHBV纤维毡而言,在静电纺丝过程中,由于其结晶速度较快,溶剂快速挥发使结晶受阻现象未出现,所以结晶度不降反升。3.在加酶降解的过程中,不同比例的PHBV、PCL与PLLA电纺纤维膜在脂肪酶、脂肪酶(猪胰)中降解速度明显加快,降解速度远远快于未加酶及普通膜的降解速度。所得电纺膜中随着所含聚乳酸的比例增加,降解速度明显加快,这是因为PCL、PHBV降解过程产生的小分子酸也能间接催化聚乳酸降解。降解过程中电纺纤维膜的失重率和吸水率与降解时间而增加。4.对PLLA/PCL(60:40)的电纺膜通过三种气体对其进行低温等离子体改性,研究比较发现,改性后的膜接触角较之前有明显降低,表明材料的亲水性增强。将改性后的支架材料接枝透明质酸,采用MTT法和扫描电镜研究成纤维细胞在改性前后材料表面的生长和增值情况,评价改性后PLLA/PCL(60:40)电纺纤维支架的相容性。结果表明:改性接枝支架细胞增值能力得到显著提高,预示在组织工程支架领域将有着良好的应用前景。更多还原

【Abstract】 Scaffold plays an important role in tissue engineering strategies. The scaffolds were widely applied for different tissue engineering via an electrospinning technique at present.The paper gives a systematic study of the preparation of tissue engineering scaffolds by electrospining. The results showed that the electrospinning nanoscaffolds mimicked Extrocelluar Matrix (ECM) well, with high porosity, well interconnected, and high surface-to-volume ratio that was suitable for cell growth.The PLLA, PCL, PHBV, hyaluronic acid (HA) were choosed as tissue engineering scaffold materials. The composite nanoscaffolds were prepared by electrospining and plasma technique. The structure, morphology, storage modulus and loss factor properties, crystallization property and hydrophilicity of the electrospun fibers were characterized by scanning electron microscopy(SEM), dynamic mechanical properties(DMA), thermal analysis (DSC), wide angle X-ray diffraction(WAXD) and contact angle. Degradation behaviors were investigated during the enzymatic degradation in PBS aqueous for different time. Dermal fibroblasts were seeded on the electrospun scaffold and the cells in material growth situation were evaluated by SEM. The fiber mats were tested for tissue engineering scaffold applications. The main results wered listed as follows:1. PHBV, PLLA, PLLA/PHBV electrospun ultra-fine fibers were prepared by using dichloroethane/DMF (60:40) as solvent systems. PLLA, PCL, PLLA/PCL electrospun fibers were prepared by chloroform/DMF(60:40) . The result indicated that the fibers were smooth and uniform with the interwoven and porous morphology. All of them were suitable for the solvent of PLLA, PHBV, PCL and the mixture for electrospining.2. Although the electrospining process results in alignment and orientation of the polymer chains within the fiber to a great extent, crystallation structure can not be developed very well due to the quick solidification of the fibers. Thus, the crystallinity of PCL and PLLA fibrous mats was lower than that of the corresponding films according to DSC and WXAD results. The phenomenon of the blocked crystallization did not occur because of the fast crystallization rate in the process of electrospinning. So the crystallinity of PHBV was increased after electrospinning.3. Degradation velocity of different proportion of PLLA/PCL and PLLA/PHBV fibrous membrane were greatly accelerated with the addition of enzyme, which were far faster than that of PCL and PHBV fibrous membrane without enzyme. With an increase in the proportion of polylactic acid (PLLA), the degradation speed was obviously speeded up. It is because small molecule acid produced in the course of PCL and PHBV degradation had indirectly catalyzed the degradation of polylactic acid. Weight-loss ratio and water absorption rate of the fibrous membrane were proportionally increased with the degradation time.4. The PLLA/PCL (60:40) nanofibers were treated by three different gases in the low-temperature plasma. The results showed,water contact angle of the films reduced significantly after plasma treatments, and the hydrophilic of composite scaffolds were enhanced. PLLA/PCL (60:40) nanofibers were prepared by electrospining technology and haluronic acid was grafted on the surface ultra-thin fibers after the low-tempature plasma treatment.Dermal fibroblasts were seeded on the electrospun scaffold and the cell proliferation was also evaluated by MTT method and SEM. It can be concluded that the cell affinity of the PLLA/PCL (60:40) fibers were greatly improved by haluronic acid grafting. And it may have great potential applications of tissue engineering scaffold.更多还原