磁性多孔材料的制备及其固定化漆酶的应用研究

安徽大学 硕士学位论文 磁性多孔材料的制备及其固定化漆酶的应用研究 姓名：张红 申请学位级别：硕士 专业：有机化学 指导教师：毕红 2010-05 摘 要(Abstract) I 摘 要 磁性多孔材料因兼具有磁性材料的磁性能和多孔材料的高比表面积及大的 孔体积而受到人们极大的关注, 已被广泛用于固定化酶、细胞分离、靶向载药、 DNA 分离等生物医学领域，以及高密度磁存储、磁流体、催化等工业领域。因 此，设计和合成出不同结构的磁性多孔材料具有显著的科学意义和应用价值。本 论文旨在传统制备磁性多孔复合材料的基础上， 进一步探索单一组分磁性多孔材 料的合成新途径，研究材料的固定化漆酶性能与材料的结构和形貌之间的关联。 详细内容如下： 1. 以 FeCl3· 6H2O、FeCl2· 4H2O 和 NaOH 为原料，采用化学共沉淀法制备出 磁性 Fe3O4纳米颗粒，在进行初步的洗涤以后，通过 TEOS 的水解反应在磁性 Fe3O4纳米颗粒的表面沉积一层多孔 SiO2壳，最终制备出具有复合结构的磁性多 孔 Fe3O4/SiO2材料。采用 X 射线衍射（XRD） 、扫描电子显微镜（SEM） 、BET Analyser、多功能振动样品磁强计 VersaLab 系统等测试手段分别对合成的样品 的晶体结构、表面形貌、孔结构和磁性能进行了表征。将制得的磁性多孔 Fe3O4/SiO2复合材料用于漆酶的固定化。该固定化漆酶的表观活性较高，在循环 使用 14 次以后其操作稳定性仍能保持 47.44%。通过对比可知，高温热处理过程 使材料的比表面积和孔体积均有所减小，同时， 复合材料中氧化铁的结晶情况变 化较小， 且热处理后的材料固定化漆酶的表观活性和操作稳定性较未经热处理的 材料固定化漆酶均都有显著提高。 2. 通过聚乙烯醇（PVA）和聚乙烯吡咯烷酮（PVP）或可溶淀粉混合溶胶对 二茂铁进行包裹，采用戊二醛作为交联剂，再将混合物在空气气氛中高温热处理 制备得到不同形貌的磁性多孔或中空氧化铁微粒。考察不同包裹剂、不同 PVP 和二茂铁的掺杂量、以及热处理时间对材料的形貌和性能的影响。采用 XRD、 HRTEM（高分辨透射电子显微镜） 、SEM、BET Analyser、VSM（振动样品磁 强计）分别对样品的晶体结构、形貌、表面孔结构和磁性能进行表征。结果表明， 随着热处理时间的延长，不仅可以提高样品的纯度还可以增加样品的结晶性。通 过调节包裹剂的种类和掺杂量， 可以调控样品的形貌、 尺寸、 孔结构以及结晶性。 将不同形貌的磁性多孔氧化铁用于漆酶的固定化， 初步考察了该固定化漆酶的表 摘 要(Abstract) II 观活性和操作稳定性。结果表明，固定化漆酶的初始表观活性随材料的成孔率和 孔体积的增加而增加，而操作稳定性主要随孔径的减小而增加。 关键词：磁性；多孔材料；氧化铁； 漆酶；固定化 摘 要(Abstract) III Abstract Recently, magnetic multi- porous materials have received considerable attentions in many current and emerging areas of technology for its magnetic property, large surface area and pore volume, which including enzyme immobilization, cell separation, drug delivery, DNA separation, high- density magnetic data storage media, ferro- fluids and catalysis. Therefore, it is of great significance to design and synthesize magnetic multi- porous materials with different micro/nano- structures. The objective of this thesis is to explore a new avenue for the synthesis of mono- component magnetic multi- porous materials and investigate the effects of the morphology and structure on their behavior of immobilizing laccase. The detailed works can be summarized as follows: 1. Magnetic Fe3O4 nanoparticles were synthesized by using f erric trichloride, ferrum(II) chloride and sodium hydroxide as starting materials via a chemical co- deposition method. After primary washing by distilled water, magnetic mesoporous Fe3O4/SiO2 nanocomposite was synthesized successfully with magnetic Fe3O4 nanoparticles embedded in mesoporous silica microparticles through the hydroxylation of tetraethyl silicate. The crystallinity, surface morphology, pore structure and magnetic properties of the synthesized nanocomposite were characterized by using the X- ray diffractionmeter (XRD), scanning electron microscopy (SEM), BET analyzer, and Versalab techniques. Subsequently, the nanocomposites were utilized to immobilize laccase and the results indicated that the immobilized laccase still had good apparent activity and operational stability. It was noted the immobilized laccase still kept a high operational stability of about 47.44% after having recycled for 14 times. In addition, it was found that the BET surface area and pore volume of the nanocomposites decreased whereas the apparent activity and operational stability of the immobilized laccase were significantly increased after annealing treatment. 2. Magnetic multi- porous and hollow iron oxide particles have been prepared successfully by decomposition of f errocene (C5H5)2Fe) which dispersed within the 摘 要(Abstract) IV mixed sol composed of polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) or PVA and soluble starch, respectively. The addition of glutaraldehyde may increase crosslinkage between PVA and starch chains or PVA molecules themselves. Then all of the organics were removed by thermal treating in air atmosphere, the final products were obtained. The influence of mass ratio of ferrocene to polymers on the morphology and structure of the products w ere also investigated. The crystallinity, surface morphology, pore structure and magnetic properties of the products were characterized by using the X- ray diffractionmeter (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), BET analyzer and vibrating sample magnetometer (VSM). The results indicated that the purity and crystallinity of the product could be improved as the annealing time prolonged. Moreover, the morphology, size, pore structure and crystallinity of the products could be tuned by changing the amount and variety of the capping polymers. The magnetic multi- porous iron oxide particles with different morphology and micro/nano- structure were utilized for immobilization of laccase. The results showed that the apparent activity of the immobilized laccase increased as the pore volume increasing. In addition, the operational stability of the immobilized laccase increased when the pore diameter decreased. Key words: magnetic, multi- porous material, iron oxide, laccase, immobilization 2 第一章 绪 论 1 第一章 绪 论 § 1.1 引言 随着材料科学的不断发展， 人们对材料性能的要求也越来越高。 高比表面积、 均一尺寸、以及具有磁特异