具整合素结合模块的细菌纤维素真皮仿生支架的电化学构建

Follow the principle of tissue engineering, bacteria will be cultured by biological methods to get the natural 3D scaffolds - bacterial cellulose (BC). Such scaffolds will be modified by electrochemical methods at the level of molecular and microstructure. Building an artificial dermis bionic scaffold with appropriate pore size,suitable degradation rate and integrin binding module(IBM).Study the characteristics of cellulose molecule under the electric field. Using electric oxidation methods, hydroxy of scaffolds can be oxidized to functional groups (aldehyde and carboxyl), which should change the degradation properties of scaffolds at suitable rate and build a proper aperture on the surface of scaffolds. Such bionic scaffolds can simulate the human dermal extracellular matrix (ECM) at maximum extent. Because of the chemically inert of cellulose, the reactions between cellulose and proteins will not react under normal conditions. In our preliminary studies, we found that the complexes of cellulose and casein were quickly formed on anode. Electric field might change the availability of hydroxy in cellulose and affect its reactivity with protein. In this study, the complexes of integrin binding module and cellulose will be synthesis by electrochemical methods. IBM can provide binding sites for seed cells furthermore influencing the biocompatibility of scaffolds.Integrins are essential for cell migration and invasion, not only because they directly mediate adhesion to the ECM, but also because they regulate intracellular signaling pathways that control cytoskeleton organization, force generation, gene transcription and survival .The applications of electrochemistry may provide a suitable way to get an idea bionic scaffold with IBM.In the current scenario of regenerative medicine there is a great demand for the production of new materials appropriate for skin replacements. In this work BC, a promising biomaterial, will be functionalized. The strategy used be aimed at improving cell adhesion to BC, through complexed with protein containing adhesion sequences and building IBM . For artificial chemical modifacation based on cellulose the use of a IBM (exhibiting a high affinity and specificity ) is an excellent feature, as a IBM can be combined with virtually any biologically active protein and used to modify cellulose-based materials. The chimeric peptides were able to enhance seed cell adhesion to BC and stimulate tissue generation.Through the electrochemical techniques,a IBM will be made on the surface of BC, making BC has the stent signal recognition, conduction, and thus involved in the process of cell attachment, proliferation and viability, and thus mimicks the native skin with certain biological functions.

遵循组织工程学原理，从仿生学角度出发，以天然高分子聚合物细菌纤维素（BC）为研究对象，利用电场，对其进行分子水平和微观结构的修饰及改性，构建一种孔径适当、降解速率适宜、具细胞识别模块的组织工程人工真皮仿生支架。利用纤维素化学惰性与其超分子结构密切相关的特点，观察纤维素在电场下分级结构的变化及其反应特性的改变。针对BC支架降解性能不佳的情况，采用电化学间接氧化法，引入功能基团改变材料的降解性能，同时降低成本，减少废液排放；针对BC支架与种子细胞之间没有信息交换的弊端，在本课题组前期研究成果的基础上，采用电化学技术在BC支架表面接入具有生物活性的蛋白质，形成整合素结合模块，获得具有细胞简识别系统的BC仿生支架，使支架获得信息传递功能，介入细胞粘附、增值、分化等过程。本课题主要目的是寻找电化学技术与纤维素化学的结合点，为纤维素绿色衍生化反应提供理论基础；提供一种全新的仿生材料制备方法及实验依据。

摘要：由于项目经费限制，整合素蛋白价格昂贵，改用明胶和酪蛋白替代，考察细菌纤维素和蛋白质的反应特性。利用木醋杆菌生物发酵制备了细菌纤维素，对细菌纤维素的含水性、孔隙率、透湿性进行了表征。采用了间接电化学氧化法，以高碘酸钠为氧化介质，成功将细菌纤维素氧化成二醛细菌纤维素，对产物的结晶指数、醛基含量、保水值、水溶性指数进行了测试，分析了样品的红外光谱、SEM、XRD的特性，认为可以通过间接电化学氧化将醛基带入细菌纤维素中，使其具有和生物活性的蛋白质结合的能力。将二醛细菌纤维素与不同质量分数的明胶结合，考察复合物的降解性能、红外光谱，孔隙度、SEM、热力学稳定性等特性，结果表明该细菌纤维素复合物具有降解性能，并有一定的孔隙度，同时热力学较为稳定的特性，可以作为一种理想的生物皮肤支架材料应用。在电场下，直接对细菌纤维素与酪蛋白进行复合，对复合物的溶解性、红外光谱、XRD、TG等特性进行了表征，结果表明该复合物具有与反应物完全不同的理化特点，推测是由于电场的作用，赖氨酸侧链上的氨基和多糖分子还原末端的羟基之间的羟氨反应，即Maillard反应的结果。通过上述实验，认为通过电场或化学试剂的改性，可以在反应活性低下的BC膜上连接活性的蛋白质基团，使构建具生物活性的BC仿生支架材料成为可能。