银/聚吡咯/壳聚糖核壳结构纳米球的制备及其对抗药菌的抑制机理

Due to the widely use and misuse of antibiotics, bacterial resistance strengthens gradually and drug-resistant bacteria are endangering the health of human being seriously. The project aims to explore the synthesis method and process of new structural composite materials, and bring efficient and continuous inhibitory activity against drug-resistant bacteria into effect. Core-shell materials have excellent physical and chemical properties in many composite materials because of their peculiar microstructure. The materials have extended to many scientific intersection fields of biology, material science and so on. They show an attractive prospect in the aspect of medicine, catalysis and bacteriostasis, etc..The new composite material is prepared on the base of the biocompatibility of chitosan, the no drug-resistance of silver nanoparticles, and the embedded effect for nano-metal of polypyrrole. Silver/chitosan (Ag/CS) complex is prepared by the chelation of chitosan and silver ions using sol-gel method，and Ag@Ag+/CS composite latex will form through partial reduction of silver ions. Silver/polypyrrole (Ag/PPy) core-shell structure nanospheres will be prepared via the oxidative polymerization of pyrrole monomer on the surface of silver nanoparticles. Silver nanoparticles forming in the preparation process play a role of a template while other template is absent. Chitosan attached to the surface of Ag/PPy nanospheres due to electrostatic interactions in the acidic solution. Silver/polypyrrole/chitosan (Ag/PPy/CS) core-shell structure nanospheres is prepared when chitosan coated on the surface of Ag/PPy nanospheres by cross-linking reaction with the latter as a template. Then the resultant structure will form with silver nanoparticles as the kernel, chitosan as the shell and polypyrrole as the middle layer. Thereby the composite antibacterial agent inhibiting the reproduction of drug-resistant bacteria efficiently will be prepared. .The tests of antimicrobial property againest drug-resistant bacteria of as-prepared core-shell nanospheres will be carried out. The relationship between the component and microscopic structure of the nanospheres and the antibacterial activity will be explored, and bacteriostatic mechanism will be revealed, too. The foundation will be established in order to broaden the application of the chitosan antibacterial agent in the field of health-care, tissue-engineering and bio-materials. The raw materials using in the experiment are low or nontoxic reagents, which provide a theoretical basis for the green research and the development of efficient antibacterial agent.

由于抗生素的广泛使用和滥用，细菌的抗药性逐渐加强，抗药菌严重威胁人类的健康。本项目旨在探索新型结构复合材料的合成方法及过程，实现对抗药菌的高效、持续抑制作用。基于壳聚糖的生物相容性、纳米银的无耐药性，聚吡咯对纳米金属的包埋作用，以及核壳结构对组成材料复合性能的调控作用，拟在不加入其它模板剂的条件下，以复合材料制备过程中形成的纳米粒子为模板，通过吡咯单体在银粒子表面的氧化聚合，制备银/聚吡咯核壳结构纳米球；继而以银/聚吡咯纳米球为模板，通过交联反应使壳聚糖包覆在银/聚吡咯纳米球表面，形成以纳米银为内核，壳聚糖为外壳，聚吡咯为中间层的三层核壳结构纳米球。该新型材料中纳米银核和聚吡咯中间层的引入，可显著提高原始壳聚糖基材料对抗药菌的抑菌活性。探索银/聚吡咯/壳聚糖纳米球的组成、结构与其对抗药菌抑菌活性的关系，揭示抑菌机理，为拓宽壳聚糖类抗菌剂在医疗卫生、组织工程及生物材料等领域的应用奠定基础。

由于抗生素的广泛使用和滥用，细菌的抗药性逐渐加强，抗药菌严重威胁人类的健康。本项目旨在探索新型结构复合材料的合成方法及过程，实现对抗药菌的高效、持续抑制作用。. 基于壳聚糖(CS)的生物相容性、纳米银的无耐药性，聚吡咯(PPy)对纳米金属的包埋作用，以及核壳结构对组成材料复合性能的调控作用，在不加入其它模板剂的条件下，以复合材料制备过程中形成的纳米Ag为模板，通过吡咯单体在Ag粒子表面的氧化聚合，制备Ag/PPy核壳结构微球；继而以Ag/PPy微球为模板，通过交联反应使CS包覆在Ag/PPy微球表面，形成以纳米Ag为内核，CS为外壳，PPy为中间层的三层核壳结构微球。模板法避免了其它非微球组成分子的引入，所得Ag/PPy/CS微球的纯度较高。SEM观察到复合微球呈规则的球形，表面光滑，粒径约为5 μm，分布均匀。TEM结果显示纳米银颗粒呈球形或椭球形，平均粒径为10~20 nm，均匀分散于Ag/PPy/CS微球中。 . 以氨苄青霉素抗性大肠杆菌和金黄色葡萄球菌为模型测定Ag/PPy/CS微球对抗药菌的抑菌效果。抗菌评价结果表明，Ag/PPy/CS微球随着微球浓度的增加对抗药性大肠杆菌和金黄色葡萄球菌的抑菌性能均增强。Ag/CS微球对抗药性大肠杆菌和金黄色葡萄球菌的最低杀菌浓度分别为1.5 g/L和0.6 g/L；Ag/PPy/CS微球对此两种菌的最低杀菌浓度分别为1.3 g/L和0.6 g/L。此最低杀菌浓度数值低于相关文献数据。以上结果表明，Ag/PPy/CS微球抗菌剂对抗药性菌的抑制作用与对普通革兰氏菌一样有明显效果。. 所得微球结合了交联CS的生物相容性和可降解性、PPy对金属粒子的包埋和缓释作用、纳米Ag的耐药性和高分散性，三层材料协同发挥抑菌作用，因此，Ag/PPy/CS核-壳-壳结构微球是一种较其它非核壳结构CS基材料更为优良的抗菌剂。通过微球对氨苄青霉素抗性大肠杆菌的抑菌效果测定和机理研究，揭示出复合微球的核壳结构与其对抗药菌的抑菌性能的关系。探索了复合微球中PPy层对纳米Ag的可控释放作用及纳米Ag提高CS抑菌性能的原理，并揭示出Ag/PPy/CS微球抗菌剂的抑菌机理，为制备抑制抗药菌繁殖的高活性复合抗菌剂提供了理论依据，从而拓宽CS类抗菌剂在医疗卫生、组织工程及生物材料等领域的应用。