【作者】 杜桂焕；

【导师】 刘祖黎；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2006， 博士

【摘要】 本文用几种方法对Fe3O4磁性纳米颗粒进行表面修饰,得到了能应用于生物学领域的复合纳米颗粒。首先是创造性地制备了具有三层半导体纳米外层和一个磁性纳米颗粒核的双功能纳米复合材料,该材料是在粒径分布均匀的磁性纳米颗粒表面先沉积一层半导体纳米层,得到同时具有磁性和荧光性能的双功能纳米复合材料,在此基础上,通过再在上面包覆带隙较宽的半导体纳米层,得到荧光效率显著增加的双功能复合纳米颗粒,同时,为了调节两半导体纳米晶体之间的晶格失配情况,使用了中间层的方法。在制备用于老年痴呆症早期诊断的磁共振试剂中,我们将Fe3O4磁性纳米颗粒连接上淀粉样蛋白,在制备过程中,先将Fe3O4磁性纳米颗粒表面进行官能化,再通过化学键连接的方式连接生物分子,将得到的试剂在转基因小鼠上实验,并在磁共振仪上显影,得到了有明显改变的小鼠脑部磁共振图像。同时,为了得到具有良好保护性能的磁性纳米颗粒复合物,我们将既有良好抗腐蚀性,又可以用在生物学体系的SiO2作为包覆物对磁性纳米颗粒进行表面修饰,得到了性能良好的Fe3O4/SiO2复合纳米颗粒,我们将该复合纳米颗粒进行了生物学连接实验,发现其与生物分子具有良好的连接性能。然后我们用透射电镜、荧光显微镜等设备观察了所制备样品的形貌,用X射线光电子能谱仪、X射线衍射等研究了样品的结构,用荧光光谱仪测试了双功能纳米材料的荧光效率,用红外光谱仪分析了部分样品的表面官能化情况,结果发现经过表面修饰后的材料,都有明显的性能改进。所制备的材料不仅具有颗粒均匀性,而且分散良好。用半导体材料修饰后得到的复合材料,不仅兼有磁性和荧光性能,而且荧光效率有较大提高,该制备方法为以后的性能改进打下了良好的基础、提供了新的思路;用表面官能化后连接淀粉样蛋白得到的磁性纳米颗粒,不仅是磁性纳米材料生物学应用的良好实例,还为未来临床诊断老年痴呆提供客观的依据,具有明显的社会效益和经济效益;通过SiO2修饰后的磁性纳米复合材料,具有良好的抗腐蚀性能,不仅可以耐很强的酸碱,而且可以耐较高的温度,该纳米复合材料还具有良好的生物分子连接性。更多还原

【Abstract】 Magnetic Fe3O4 nanoparticles were modified by other substances to get the nanocomposites which can be used in biologic field. Semiconductors were deposited on surface of magnetic Fe3O4 nanoparticles to get bifunctional nanocomposites. Functional groups were also used to modify magnetic Fe3O4 nanoparticles and connected them to biomolecular to form the nanocomposits named ultrasmall supreparamagnetic iron oxide nanoparticles– Aβ(SPION- Aβ). SiO2 was coated on magnetic Fe3O4 nanoparticles to get Fe3O4/SiO2 nanocomposites.Fe3O4/CdSe/ZnS magnetic fluorescent bifunctional nanocomposites were obtained by depositing heterogeneous semiconductor on magnetic nanoparticles. The structure and properties of the Fe3O4/CdSe/ZnS nanocomposites were fully characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), superconduct quantum interfere device (SQUID) and photoluminescence (PL). The results indicate that the Fe3O4/CdSe/ZnS nanocomposites are superparamagnetic and are about 8nm in size. The quantum yield of the nanocomposites increases from 2-3% in Fe3O4/CdSe to 10-15% in Fe3O4/CdSe/ZnS, together with a red shift of both the absorption peak and PL band. The increase of quantum yield is because of passivating the surface of magnetic-CdSe nanocomposites with a ZnS layer.Chemical reaction was adopted to modify surface of dextran-SPION to functional groups in this study. Fourier transforms infrared spectrometer (FTIR) and XPS were used to verify the functional groups of the modified dextran-SPION. Both morphology and magnetic property of samples were studied by TEM and vibrating sample magnetometer (VSM). The results indicate that unmodified and modified dextran-SPION were superparamagnetism and about 5nm in size. Finally, SPION was connected to biomolecular Aβto get nanocomposites named SPION-Aβ(SPION-Aβ). It was studied on transgenic mice and got obvious changes in their head imaging under magnetic field.A sol-gel procedure was used to cover Fe3O4 nanoparticles with SiO2 shell, forming a core/shell structure. The core/shell nanocomposites were synthesized by a two-step process. First, Fe3O4 nanoparticles were obtained through co-precipitation and dispersed in aqueous solution through electrostatic interactions in the presence of tetramethylammonium hydroxide (TMAOH). In the second step, Fe3O4 was capped with SiO2 generated from the hydrolyzation of tetraethyl orthosilicate (TEOS). The structure and properties of the formed Fe3O4/SiO2 nanocomposites were characterized and the results indicate that the Fe3O4/SiO2 nanocomposites are superparamagnetic and are about 30nm in size. Bioconjugation to IgG was also studied. Finally, the mechanism of depositing SiO2 on magnetic nanoparticles was discussed.更多还原