聚N-异丙基丙烯酰胺/壳聚糖包覆Fe3O4纳米晶簇核/壳结构的制备及抗菌性应用

In the preparation of magnetite nanocrystals and crystal clusters, the particle size distribution is not easily controlled which often results in paramagnetic-ferromagnetic phase transition and prevents its wide spread usage in some fields. So we introduce the high-temperature hydrolysis method, by optimizing the influencing factors, to produce the magnetite nanocrystal clusters possessing the characters of perfect dispersity, narrow size distribution, and excellent magnetic property which will be used as core materials in the following process of preparation of magnetically recoverable antibacterial supports. In our ZJNSF project about preparation of magnetic nanoparticles@SiO2 core-shell structures as antibacterial supports, with the content increase of metal nanoparticles precipitated onto SiO2 surface, the phenomena of the particle desorption and aggregation were occurred which affected the antibacterial performance of the nanocomposites. Thus the second purpose of the application is using thermo-sensitive poly(N-isopropylacrylamide) (p-NIPAM) to replace silica as shell materials to produce the composite core-shell structures. It can be expected that the network structure of p-NIPAM will firmly lay hold of the embedded particles to avoid their desorption and aggregation. To improve the effect of temperature and pH value on swelling-deswelling dynamic behaviour of p-NIPAM, semi-interpenetrating polymer network p-NIPAM/chitosan (CS) will be designed by combining linear carboxymethyl chitosan with p-NIPAM. Furthermore, chitosan is highly effective against bacteria because of its broad-spectrum antibacterial property. In the following work, the magnetic composite antibacterial agent, Ag-embedded magnetite@p-NIPAM/CS, will be prepared by introducing Ag nanoparticles into polymer network via in-situ reducing synthesis. And we will also check its synergistic action and magnetically recoverable antibacterial effect of the composite antimicrobial.

为解决Fe3O4纳米晶及晶簇制备中出现的粒度分布不易控制及生长粒径过大导致顺磁-铁磁相变的问题，该申请提出采用高温水解法，并通过优化反应参数以制备具有良好分散性、粒度分布较窄且磁性能优越的Fe3O4纳米晶簇。后续工作以此为核材制备可磁回收重复利用的核/壳结构复合抗菌剂。针对申请人在研的SiO2包覆磁性粒子作为抗菌剂载体应用中出现的金属粒子在SiO2表面脱附、团聚造成抗菌性降低的问题，申请提出将壳层包覆物改为具有开放网络结构的聚N-异丙基丙烯酰胺（p-NIPAM）以固载抗菌剂粒子来解决该问题。为改善温度及pH值变化对p-NIPAM的影响并提高金属抗菌剂的抗菌性能，该课题设计将具有广谱抗菌性的壳聚糖（CS）与p-NIPAM联接制备半互穿壳层结构。以上述所得Fe3O4@p-NIPAM/CS为载体，在壳层网络结构中导入纳米银，制备磁性复合抗菌剂，通过其协同作用和优势互补，提高抑菌率并延长抗菌周期。

为解决Fe3O4纳米晶及晶簇制备中出现的粒度分布不易控制及生长粒径过大导致顺磁-铁磁相变的问题，该项目提出采用高温水解及溶剂热法两种方法共同探讨，并通过优化反应参数制备得到具有良好分散性、粒度分布较窄且磁性能优越的Fe3O4纳米晶簇。后续工作以此作为核材制备了可磁回收重复利用的核/壳结构复合抗菌剂。针对申请人在研的SiO2包覆磁性粒子作为抗菌剂载体应用中出现的金属粒子在SiO2表面脱附、团聚造成抗菌性降低的问题，申请提出将壳层包覆物改为具有开放网络结构的聚N-异丙基丙烯酰胺（p-NIPAM）以固载抗菌剂粒子来解决该问题。在壳层网络结构中导入纳米银，通过种子诱导生长模式制备磁性复合抗菌剂，通过其协同作用和优势互补，提高抑菌率并延长抗菌周期。基于实验结果及文献报道，本项目也对磁性复合材料的抗菌机理进行了深入探讨。该课题在设计将具有广谱抗菌性的壳聚糖（CS）与p-NIPAM联接制备半互穿壳层结构时发现，聚合物的严重团聚使所得Fe3O4@p-NIPAM/CS载银复合体系的抗菌效果没有增强，反而减弱。为扩大该体系的适用范围，项目基于磁性纳米簇，通过一步共沉积法构建了Fe3O4@SiO2@TiO2/AgNPs光催化协同抗菌体系并取得了良好的抗菌活性结果，同时，通过牺牲剂叔丁醇和溴酸钾的使用确定了在抗菌过程中起主要作用的活性氧的种类。