温敏性纤维素纳米晶须的可控聚合与生物相容性评价

发布时间：2018-04-25 05:32

  本文选题：细菌纤维素纳米晶须 + 温敏性　； 参考：《华中科技大学》2016年博士论文

【摘要】：细菌纤维素(Bacterial Cellulose,BC)是木醋杆菌生产的天然高分子材料,拥有纳米纤维组成的三维网络结构。通过β-(1,4)-糖苷键链接而成的纤维素高分子链,表面具有大量的羟基基团,容易通过各种化学方法进行功能性修饰,其中包括高分子接枝反应(耦合接枝和引发接枝)、阳离子化反应以及其他共价和非共价的反应。BC兼具优良的生物相容性、高结晶度以及良好的机械性能等独特的理化性质,在化工和医用材料等领域具有广阔的应用前景。为了进一步拓展BC在医用材料方面的应用前景,本文制备了纳米尺寸的细菌纤维素(细菌纤维素纳米晶须,Bacterial Cellulose Nanowhisker,BCNW),通过温敏性高分子对其进行功能性修饰,得到新的具有温敏性的生物材料,并对该生物材料作为栓塞材料的潜在应用前景进行了初步的研究。本文首先对酸水解和冷冻研磨制备BCNW的方法进行比较,结果显示酸水解的方法能够更彻底的破坏BC膜的网络结构得到纳米尺寸的BCNW;对BC的亲水性、持水性、机械性能以及生物相容性进行测试,结果表明BC具有很好的亲水性和持水性(含水量达97%),拥有典型的水凝胶性质,展现出良好的生物相容性。接下来,通过原子转移自由基聚合(Atom Transfer Radical Polymerization,ATRP)将最具有标志性的温敏聚合物聚N-异丙基丙烯酰胺(PNIPAM)引发聚合在纳米晶须的表面形成温敏共聚物BCNW-g-PNIPAM。通过傅立叶转换红外光谱和核磁共振氢谱证明了该聚合作用的成功性。经透射电镜展示了其纳米结构伴随温度的变化而产生的差异。差示扫描量热法证明该共聚物具有温敏性质,并且其低临界溶解温度依然低于人体温度。细胞毒性实验表明了BCNW对于提高材料的生物相容性的重要性。本文进一步研究,选择生物相容性较好的温敏高分子聚2-甲基-2-丙烯酸-2-(2-甲氧基乙氧基)乙酯(PMEO_2MA)进行相关温敏纳米材料的制备。通过ATRP的聚合方法得到具有温敏性质的BCNW-g-PMEO_2MA,并通过傅立叶转换红外光谱和核磁共振氢谱证明了该聚合作用的成功性。浊度法测试表明该共聚物的低临界溶解温度为28.5℃。然后添加寡聚乙二醇甲基丙烯酸酯(OEGMA)与PMEO_2MA进行共混聚合,接枝到BCNW表面,通过控制两种单体共混聚合的比例,得到了低临界溶解温度为31.5℃的温敏性共聚物BCNW-g-P(OEGMA-co-MEO_2MA)。BCNW-gPMEO_2MA与BCNW-g-P(OEGMA-co-MEO_2MA)的低临界溶解温度都展现出离子依赖性。共聚物的细胞毒性实验证明其细胞相容性更好,所以该温敏共聚物具有作为栓塞材料的潜力。
[Abstract]:Bacterial cellulose (Bacterial Celluloseus) is a natural polymer material produced by Acetobacter xylophilus, which has a three-dimensional network structure composed of nanofibers. A chain of cellulose polymers linked by 尾 -chlorion 4- glucoside bonds has a large number of hydroxyl groups on the surface, and it is easy to be modified by various chemical methods. It includes polymer graft reaction (coupling grafting and initiating grafting, cationic reaction and other covalent and non-covalent reactions. BC has excellent biocompatibility, high crystallinity and good mechanical properties, etc.) It has a broad application prospect in the fields of chemical industry and medical materials. In order to further expand the application prospect of BC in medical materials, we prepared bacterial cellulose (bacterial Cellulose nanowhisker BCNWN) with nanometer size, and modified it by thermo-sensitive polymers. A new thermosensitive biomaterial was obtained and the potential application prospect of the biomaterial as an embolic material was preliminarily studied. In this paper, the methods of preparing BCNW by acid hydrolysis and freezing grinding are compared. The results show that the method of acid hydrolysis can destroy the network structure of BC membrane more thoroughly to obtain nano-size BCNW. The mechanical properties and biocompatibility of BC were tested. The results showed that BC had good hydrophilicity and water holdup (water content was 97%, typical hydrogel property, and showed good biocompatibility. Next, the most iconic thermo-sensitive polymer, poly (N-isopropylacrylamide) PNIPAM, was initiated by atom transfer radical polymerization (Atom Transfer Radical Polymerization) to form a thermo-sensitive copolymer BCNW-g-PNIPAM on the surface of nano-whiskers. The success of the polymerization was proved by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Transmission electron microscopy (TEM) shows the difference between the nanostructures and the temperature. The differential scanning calorimetry (DSC) shows that the copolymer has the property of temperature sensitivity and its low critical solution temperature is still lower than the human body temperature. Cytotoxicity tests show the importance of BCNW in improving the biocompatibility of materials. In this paper, a thermo-sensitive polymer, poly (2-methyl-2-acrylic acid) -2-methoxy ethoxy ethyl ester (PMEO _ 2MA) with good biocompatibility, was selected to prepare the thermo-sensitive nano-materials. The thermo-sensitive BCNW-g-PMEO2MAwas obtained by the polymerization of ATRP. The success of the polymerization was proved by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) hydrogen spectroscopy. The turbidimetric test showed that the low critical solution temperature of the copolymer was 28.5 鈩，

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