新型甜菜碱改性壳聚糖及其协同抗菌活性、抗菌机理和生物相容性研究

Due to the great potential in both the academic and social economic field, chitosan (CS) modification is becoming one of the hottest research topics at domestically and internationally. However, the current study of CS modification focuses on the improvement of antimicrobial activity and water-solubility through quaternarization and carboxylation. The relationship between the amino amount in CS remaining after modification and its antibacterial activity is still unclear.. On the basis of our preliminary studies, in this project, we propose a novel idea to prepare betaine modified CS (BCS) and quaternary ammonium salt - betaine modified CS (QBCS) with high antibacterial activity and biocompatibility. The antibacterial activity and biocompatibility of CS derivatives can be regulated based on the structure-activity relationships between molecular structure, surface structure of CS derivatives, and their antibacterial activity and biocompatibility.. In addition, a variety of advanced characterization methods will be used to track the action process of CS derivatives in bacteria. Particularly, confocal laser scanning microscopy (CLSM) and fluorescence microscopy (FM) are used to in situ observe the parameter changes of bacterial internal structure and morphology, and to further investigate the structural changes of bacteria under stress induced by CS derivatives, and to explore the interaction between CS derivative-concentration and bacterial behavior and survival, and to study the target role of CS derivatives with respect to bacteria. Based on these results, the mechanism for the antibacterial activity of CS derivatives, and synergistic antibacterial principle will be set up. This project will focus on studying correlations between surface structure (surface charge and surface hydration state, etc.) and protein non-specific adsorption of CS derivatives, and explore the nature of CS derivatives surface biocompatibility on molecular level.

由于巨大的学术价值和社会经济效应，围绕增强抗菌性和降低毒性的壳聚糖(CS)改性研究成为当前国际的热点课题。然常用的季铵化改性既增加抗菌性也增加毒性，而羧基改性可降低毒性也降低抗菌性。改性后残留的氨基量与其抗菌活性的关系也不甚明了。本项目拟通过结构设计，制备兼有高抗菌和生物相容性的甜菜碱改性CS和季铵盐-甜菜碱改性CS。通过研究分子结构、表面结构、残余氨基量等与抗菌活性和生物相容性的构效关系，调控CS衍生物的抗菌活性和生物相容性，阐明其协同抗菌原理。通过引入荧光基团跟踪CS衍生物与细菌作用过程，实时观测细菌形貌参数的变化；结合细胞膜的完整性分析、蛋白质组学和代谢组学研究，探索CS衍生物作用于细菌的靶点，揭示其抗菌作用机制。可拓宽CS的应用范围，为CS表面改性提供理论依据，有助于促进生物材料表面科学的发展，具有较重要的科学研究价值和社会效应。

壳聚糖(CS)分子结构中C2位上的氨基（NH2）在弱酸性下可质子化而显聚阳离子的广谱抗菌和抗病毒性，又因其资源丰富，良好的生物降解性、低毒性和生物相容性，已成为国内外研究热点。然在生理pH和碱性条件下，CS结构中的NH2无法质子化而失去抗菌和水溶性，大大限制了CS的广泛应用。. 本项目设计合成了反应性的季鏻盐、甜菜碱和一系列不同链长的季铵盐，并以共价键结合到壳聚糖上，制得抗菌和水溶性的壳聚糖衍生物。项目选用生物相容和抗菌的甜菜碱改性CS，制得抗菌和生物相容的CS衍生物，引入季铵盐基团于CS结构中以制得季铵盐改性壳聚糖(QCS)和甜菜碱-季铵盐改性壳聚糖(QBCS)。系统研究了CS衍生物的分子结构和表面结构与其抗菌活性、水溶性和生物相容性的构效关系，以及残留NH2、季铵盐和甜菜碱等多基团的抗菌协同作用，获得了良好抗菌活性、生物相容性和水溶性的壳聚糖衍生物。为验证抗菌改性剂在表面带NH2和OH的材料和制品表面改性的普适性，率先将上述反应性季铵盐和甜菜碱应用于棉纺织品的抗菌防霉和除螨改性，并综合评价整理后纺织品的相关性能和安全性，通过改变抗菌整理剂配方和整理工艺，精确调控纺织品的杀菌和抗细菌粘附性，获得无毒无皮肤刺激且不负面影响织物理化性能的持久抗菌防污纺织品。本项目还采用荧光显微镜等观察了细菌接触材料表面直至死亡的过程，并采用蛋白质组学研究了甜菜碱和季铵盐的抗菌作用机制。. 项目基于壳聚糖衍生物的构效关系和多基团协同抗菌原理，优化残留NH2和OH含量、季铵盐和甜菜碱等多种抗菌功能基团，以实现对CS衍生物的抗菌活性和生物相容性的调控，可为壳聚糖抗菌和亲水改性提供一条新的途径。CS衍生物的协同抗菌活性及作用机制可为多基团协同抗菌机理研究提供一定的科学依据。反应性抗菌改性剂普适性研究，可为材料和制品表面改性提供一定的理论参考价值，项目产品有望在包装、服装，水处理、药物载体、伤口愈合敷料等方面得到广泛应用。