介孔SiO2/纳米棒Fe3O4网络复合壳层空心微球的可控制备与酶固定化

In recent years, magnetic mesoporous silica (MMS) material has been widely explored for its unique properties such as excellent magnetic responsivity, uniform pore size distribution, high surface area, low cytotoxicity, et al. MMS material is regarded as a greatly promising carrier in some biomedical applications, such as drug delivery,enzyme immobilization, and protein encapsulation. Recently, great attention is being paid to uniform MMS material with a magnetic core/mesoporous silica shell structure for its potential application. Howerver, in these studies the drug or enzyme storage capacity of the core-shell MMS material is relatively low due to the limited pore volume, which limits their utilization. In this research, a novel scheme is put forward to prepare a mesoporous hollow MMS microsphere with a hollow core, and a network-like porous composite shell constructed with mesoporous silica and Fe3O4 nanorods intercrossing, by assembling mesoporous silica into the porous shell of the Fe3O4 microsphere. Besides the common features of reported hollow MMS material, these novel hollow MMS microspheres are very stable due to the unique netwok-like composite shell structure. Furthermore, the microstructure of monodisperse microspheres can be easily controlled by changing some experiment parameters, since magnetic shell and mesoporous silica were prepared and assembled separately. The magnetic material constructed with numbers of Fe3O4 nanorods is superparamagnetic in favour of the redispersibility for microspheres. The magnetic property can also be tuned by changing the microstructure including the ratio of length to diameter, and the size of the Fe3O4 nanorods under different experimental conditions. In the project, a synthetic route of a novel hollow MMS microsphere is developed, combing a template-assisted method with a multi-step chemical liquid deposition process. The microstructure will be disigned and tuned for a hollow MMS microsphere with excellent magnetic property and good enzyme immoblization capacity. The inherent relationship between the microstructure and properties will be further investigated.

近年来，具有良好介孔材料性能并易于磁场分离的新型复合材料——磁性介孔SiO2材料引起了国内外学术界的广泛关注。本项目提出一种以单分散Fe3O4纳米棒多孔壳层空心微球为载体，在多孔Fe3O4壳层中组装介孔SiO2得到一种介孔SiO2/纳米棒Fe3O4网络复合壳层空心微球。这种新型复合材料除了具有目前研究中空心磁性介孔材料尺寸均一、低密度、比表面积大等优点以外，由于磁性层、介孔层的制备过程相对独立，可以通过改变其制备条件来有效地调控材料微观结构进而对其性能进行有效调控。磁性部分由Fe3O4纳米棒组成而具有利于颗粒再分散的超顺磁性能，可以通过改变磁性层微观形态调控材料磁性能。复合材料独具的网络壳层与中空结构，可望在酶固定性能上获得突破。本项目利用模板法与多步化学液相沉积相结合开展这种新型磁性介孔微球的可控制备研究，并对其酶固定化性能进行研究，为实现具有优良性能的生物酶固定载体材料的应用奠定基础。

生物催化技术可作为解决世界所面临的能源、资源和环境保护等问题的新的途径之一。而酶作为一种高效生物催化剂，具备效率高、催化选择性强、污染小、能耗低等诸多优点。但是，酶对环境较为敏感，不稳定、易丧失生物活力，在催化反应中难以重复使用，不能回收，难以进行连续生产，极大限制了它的实际生产应用。而固定化酶技术的出现能够有效解决上述困难。.本项目已经制备一种以单分散Fe3O4纳米棒多孔壳层空心微球为载体，在多孔壳层中组装介孔SiO2得到一种介孔SiO2/纳米棒Fe3O4网络状壳层空心微球。由于磁性层、介孔层的制备过程相对独立，本项目通过改变磁性层和介孔层的制备条件，已经有效地调控磁性材料的微观结构，完成了对其性能的有效调控。.以自制的尺寸可控的单分散SiO2微球为模板，采用本课题组开发的新型化学液相沉积法得到β-FeOOH纳米棒组成的多孔壳层空心微球。在其多孔壳层中进行不同孔径尺寸和不同孔道结构的介孔SiO2的组装，空气焙烧，H2-N2气氛还原，得到介孔SiO2/纳米棒Fe3O4网络状壳层空心微球。通过调整磁性层和介孔层的制备条件，获得具有良好综合性能的介孔SiO2/纳米棒Fe3O4网络状壳层空心微球及制备方法。制备的中空微球的磁饱和强度为 13.5emu·g -1，具有超顺磁性，可实现磁场分离和回收再利用。.以不同空腔尺寸介孔SiO2/Fe3O4中空微球为载体对木瓜蛋白酶、漆酶和微过氧化物酶进行固定化，其最大固定量分别为 296mg/g、350mg/g和185mg/g。酸性条件下制备介孔SiO2/致密SiO2/Fe3O4空心微球为载体时对木瓜蛋白酶和漆酶进行固定化，固定量达到最大分别为222 mg/g和234 mg/g。且固定化漆酶及木瓜蛋白酶的pH稳定性和温度稳定性明显优于游离漆酶分子和游离木瓜蛋白酶分子。介孔SiO2/致密SiO2/Fe3O4空心微球固定化漆酶对2,4-二氯苯酚去除率约为80%。.介孔二氧化硅材料作为酶分子固定化载体不仅使固定化分子保持原有的识别、结合、催化或药理特性外，还具有高稳定性、可重复利用的特点。其不仅可以解决介孔颗粒材料在催化和分离吸附领域应用中分离困难的问题，更是在生物领域展现出巨大的应用前景。在生物医学领域这种磁性介孔二氧化硅材料作为药物载体，在磁场的诱导下能实现药物的靶向传输。