【作者】 刘瑞江；

【导师】 沈湘黔；

【作者基本信息】 江苏大学 ， 材料学， 2013， 博士

【摘要】 纳米技术已渗透到传统自然科学的各个分支,从而已产生基于多学科融合的纳米科学与技术。纳米材料科学与技术的发展,在某种程度上以解决人类社会发展过程中出现的各种问题为其终极目标。磁性氧化铁基纳米材料因其具有良好的磁向导性、生物相容性、生物降解性、低毒行为以及大比表面积等优点,可应用于生物医药和环境污水处理,是一类先进功能材料。本文以无机金属盐为主要原料,采用静电纺丝法、柠檬酸-凝胶法和快速燃烧法成功制备了α-Fe2O3纳米管、磁性Ni0.5Zn0.5Fe2O4纳米颗粒、磁性Ni0.5Zn.5FezO4/SiO2纳米复合材料和Fe203纳米颗粒；采用TG、XRD、SEM、TEM、 BET、VSM和FTIR等分析手段对磁性纳米材料的结构和特性进行了表征；根据制备的各种磁性纳米材料的特点,研究了它们在生物医药和环境污水处理上的应用可行性,其主要结果总结如下：1.磁性氧化铁基纳米结构的构筑。(1)以聚乙烯毗咯烷酮(Polyvinylpyrrolidone，PVP)为络合剂,与硝酸铁、无水乙醇反应制得前驱体溶液,采用静电纺丝和煅烧过程成功制备了α-Fe2O3纳米管。发现前驱体溶液中水含量和煅烧升温速率为影响α-Fe2O3纳米管形成的主要因素,较低的含水量和较高的升温速率有利于α-Fe2O3纳米管的形成。当溶液含水量为17wt%,升温速率为5℃/min时,500℃下煅烧2h可制备出直径为400-700nm的α-Fe2O3纳米管,并探讨了α-Fe2O3纳米管的形成机制,实现了α-Fe2O3纳米管的可控制备。(2)采用柠檬酸-凝胶法和溶液快速燃烧法制备了磁性Ni0.5Zn0.5FezO4纳米粉体和磁性Ni0.5Zn0.5Fe2O4/SiO2纳米复合材料。结果表明,当无水乙醇量为15mL时,400℃下煅烧2h所得磁性Ni0.5Zn0.5Fe2O4纳米颗粒粒径为15nm,其饱和磁化强度达45Am2/kg,与柠檬酸-凝胶法制备的磁性Ni0.5Zn0.5Fe2O4纳米颗粒的饱和磁化强度基本一致。(3)采用快速燃烧法制备了Fe203纳米粉体,制备过程简单。2.磁性氧化铁基纳米材料负载核酸研究。(1)以正硅酸四乙酯和聚赖氨酸(Poly-L-lysine, PLL)为原料先后对Fe203纳米颗粒进行表面改性,首次在Fe203纳米颗粒上成功负载了小干扰RNA(Small interfering RNA, siRNA),顺利将siRNA转运到大鼠神经元细胞内并及时释放。通过Western blot实验、免疫荧光实验和胶质瘢痕观测实验证明了siRNA转运和释放过程中未表现出细胞毒性,对靶基因能产生有效沉默,实现了siRNA的有效负载和输送。(2)在成功制备了α-Fe2O3纳米管的基础上,首次考察了室温下α-Fe2O3纳米管吸附DNA过程。当DNA初始浓度为50μg/mL时,α-Fe2O3纳米管对DNA的平衡吸附量达4.191μg/g,且吸附平衡时间为90min：基于室温下α-Fe2O3纳米管吸附DNA的动力学和吸附等温线,发现准一级动力学模型和改进的Temkin吸附模型可以很好的描述室温下α-Fe2O3纳米管吸附DNA的动力学和吸附平衡过程,揭示了α-Fe2O3纳米管对DNA的吸附机制。3.磁性氧化铁基纳米颗粒负载蛋白质研究。(1)采用二氧化硅和1-乙基-(3-二甲基氨基丙基)碳酰二亚胺盐酸盐对磁性Ni0.5Zn0.5Fe2O4纳米颗粒进行表面改性,首次在磁性Ni0.5Zn0.5Fe2O4纳米颗粒表面成功固定了初始浓度为1mmol/L的青霉素酰化酶(Penicillin G acylase, PGA),并探讨了固定化酶和游离酶在不同pH和温度下的活性。经比较发现,固定化的青霉素酰化酶的活性受pH和温度的影响程度比游离酶大大降低,表现出良好的酸碱稳定性和热稳定性；固定于磁性纳米材料之上的青霉素酰化酶循环使用11次后,相对活性依然保持近70%,表现出良好的固定化酶循环利用率。(2)发现磁性Ni0.5Zn0.5Fe2O4/Si02纳米复合材料对牛血清白蛋白(Bovine serum albumin, BSA)具有很好的吸附能力。结果表明,Si02在纳米复合材料中含量从0增大至0.05时,400℃煅烧所得纳米复合材料的比表面积由49增加至57m2/g, BSA的平衡吸附量也由22mg/g增加到49mg/g,随着二氧化硅在纳米复合材料中的含量从0.05继续增大至0.2时,比表面积由57增大至120m2/g,但BSA的平衡吸附量却保持在49mg/g左右。说明在磁性Ni0.5Zn0.5Fe2O4纳米颗粒表面包覆一层Si02可以有效增大磁性纳米复合材料对BSA的吸附量,但Si02厚度的增大无助于BSA的吸附。4.磁性Ni0.5Zn0.5Fe2O4纳米颗粒对砷和甲基蓝的吸附研究。在采用快速燃烧法和柠檬酸-凝胶法成功制备了磁性Ni0.5Zn0.5Fe2O4纳米颗粒的基础上,考察了室温下磁性Ni0.5Zn0.5Fe2O4纳米颗粒对水溶液中浓度为50-300mg/L的甲基蓝以及3mg/L砷的吸附过程。发现磁性Ni0.5Zn0.5Fe2O4纳米颗粒对水溶液中砷的吸附具有高选择性,可实现吸附后溶液中砷零残余量的目标,完全可以达到世界卫生组织(World Health Organization, WHO)饮用水的标准。同时,基于实验数据的模拟计算发现,准二级动力学模型可以很好的描述磁性Ni0.5Zn0.5Fe2O4纳米颗粒室温下吸附甲基蓝和砷的动力学过程,磁性Ni0.5Zn0.5Fe2O4纳米颗粒吸附甲基蓝和砷的等温线符合Temkin模型和Redlich-Peterson模型,揭示了磁性Ni0.5Zn0.5Fe2O4纳米颗粒表面的多样性。根据模型机理,推断磁性Ni0.5Zn0.5Fe2O4纳米颗粒对砷和甲基蓝的吸附为单层和多层的混合吸附模式。更多还原

【Abstract】 Nanotechnology has almost permeated into each branch of traditional natural science, and the nanoscience and nanotechnology has come into being the integration of multi-discipline. From the development view, the ultimate aim of the nanomaterial science and nanotechnology is to solve various problems occurring during the development of the human society.The magnetic iron oxide based nanomaterials have a good magnetic anisotropy, biocompatibility. biological degradation, low toxic behavior and large specific surface area, so they can be applied in the biomedicine and environmental sewage treatment, and are a kind of advanced functional materials. In this dissertation, the α-Fe2O3nanotubes, Fe2O3nanoparticles, magnetic Ni0.5Zn0.5Fe2O4nanoparticles and Ni0.5Zn0.5Fe2O4/SiO2nanocomposites were prepared by the electrospinning. citrate-gel, rapid combustion processes respectively with inorganic metal salts as the main raw materials, and they were characterized by the analysis methods of TG, XRD, SEM, TEM, BET, VSM and FTIR techniques. According to the characteristics of the as-prepared magnetic nanomaterials, the feasibility of their applications in the biomedicine and sewage treatment was studied, and the main results are as follows:1. Fabrication of magnetic iron oxide based nanostructures.(1) The α-Fe2O3nanotubes were prepared successfully by the sol-gel assisted electrospinning and subsequent heat treatment, with the precursor solution prepared from ferric nitrate, absolute ethyl alcohol and polyvinylpyrrolidone (PVP) as complexing agent. It is found that the water content in the precursor solution and the heating rate are the key factors affecting on the formation of the α-Fe2O3nanotubes, and the lower water content and larger heating rate are propitious to form the α-Fe2O3nanotubes. When the water content is about17wt%, heating rate is5"C/min and calcination temperature at500℃for2h, the α-Fe2O3nanotubes with diameters of400-700nm are obtained. The hollow formation mechanism of α-Fe2O3nanotubes is discussed, the controllable preparation of the α-Fe2O3nanotubes is realized.(2) Magnetic Ni0.5Zn0.5Fe2O4nanoparticles and Ni0.5Zn0.5Fe2O4/SiO2nanocomposites were synthesized by the facile citrate-gel process and the rapid combustion process, respectively. It is found that the grain size and the magnetism of Ni0.5Zn0.5Fe204nanoparticles calcined at400℃for2h with absolute ethyl alcohol of15mL were15nm and45Am2/kg, respectively, which is equivalent of Nio.5Zn0.5Fe2O4nanoparticles prepared by the facile citrate-gel process.(3) The Fe2O3nanoparticles were prepared via the rapid combustion process, and the preparation process is simple.2. The loading characteristics of nucleic acid molecules onto the magnetic iron oxide based nanostructures.(1) The surface of Fe2O3nanoparticles was modified by tetraethylorthosilicate and poly-l-lysine (PLL), and then the small interfering RNA (siRNA) was loaded onto them for the first time. The results show that the siRNA has been transferred successfully into primary rat neurons and then releases. The efficient silencing of the targeted gene with negligible cytotoxicity has been proved via the Western blot test, immunofluorescence experiments and the glial scar observations. The loading and transfer of siRNA into primary rat neurons have been achieved.(2) Based on the successful preparation of a-Fe2O3nanotubes, the adsorption of DNA onto a-Fe2O3nanotubes was determined at room temperature for the first time. The DNA adsorption onto the a-Fe2O3nanotubes can achieve a maximum value of4.19μg/g when the initial DNA concentration is50μg/mL, and the equilibrium time is90min. According to the adsorption kinetics and isotherms of DNA onto a-Fe2O3nanotubes, it is found that the pseudo-first-order kinetic model and the modified Temkin model can describe the DNA adsorption process and adsorption isotherm at room temperature, the adsorption mechanism of DNA onto a-Fe2O3nanotubes is generally revealed.3. The loading characteristics of proteins onto the magnetic iron oxide based nanostructures.(1) Tetraethylorthosilicate and l-Ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride were used as the reagents to modify the surface of the magnetic Ni0.5Zno.5Fe2O4nanoparticles. The penicillin G acylase (PGA) was successfully immobilized on the surface-modified magnetic Ni0.5Zn0.5Fe2O4nanoparticles for the first time with the initial concentration of1mmol/L, and the activities of the immobilized enzyme and free enzyme under the various conditions were systematically examined. Compared to each other, it is found that the immobilized PGA is affected less by pH and temperature than the free PGA, and the immobilized PGA exhibits good chemical stability and thermal stability of enzyme catalyst. The relative activity of the immobilized PGA is about70%after11times cycling, which suggests a good recycling rate of the immobilization of PGA.(2) The Ni0.5Zn0.5Fe2O4/SiO2nanocomposites demonstrate a good adsorption capability of bovine serum albumin (BSA). The results show that with the increase of the silica content from0to0.05and the specific surface area from about49to57m2/g, the BSA adsorption capability of the Ni0.5Zn0.5Fe204/Si02nanocomposites calcined at400℃improves dramatically from22to49mg/g. However, with a further increase of the silica content from0.05to0.2, the specific surface area increase from about57to120m2/g, the BSA adsorption for the nanocomposites remains around49mg/g, which suggests that the silica coated onto the Ni0.5Zno.sFeiO4nanoparticles improve the BSA adsorption capability, but the thickness increase of the silica content is helpless to the adsorption capability.4. The adsorptions of arsenic and methyl blue onto the magnetic Ni0.5Zno.sFe2O4nanoparticles. Based on the successful preparation of Nio sZno5Fe2O4nanoparticles by the facile citrate-gel process and the rapid combustion process, the adsorption of arsenic and methyl blue onto the magnetic Ni0.5Zno.5Fe204nanoparticles were investigated for arsenic of3mg/L and methyl blue of50-300mg/L. It is found that the adsorption of arsenic onto the magnetic Ni0.5Zn0.5Fe2O4nanoparticles has a high selectivity, the remaining amount of arsenic in solution after the absorption can achieve zero, which can reach the standard for drinking water of the World Health Organization (WHO). Based on the simulation and calculation of the experiment data, it is found that the pseudo-second-order kinetic model is in a good agreement with the kinetics data for the adsorption of arsenic and methyl blue onto the magnetic Nio.sZn0.5Fe2O4nanoparticles, and the Temkin model and Redlich-Peterson model can be used to evaluate the adsorption isotherm of arsenic and methyl blue at room temperature, which suggests that the magnetic Nio.sZn0.5Fe204nanoparticles’ surfaces are heterogeneous, and the adsorption of arsenic and methyl blue onto the magnetic Nio.5Zn0.sFe204nanoparticles can be a hybrid of monolayer and multilayer absorption mechanism.更多还原