【作者】 周小丽；

【导师】 毕红；

【作者基本信息】 安徽大学 ， 应用化学， 2007， 硕士

【摘要】 近年来，随着纳米技术的迅速发展，磁性氧化铁纳米微粒被广泛运用于生物医药领域，使其在细胞分离、固定化酶、免疫检测、靶向药物及DNA分离等方面均得到应用。此外，磁性氧化铁纳米微粒在磁记录材料、催化剂、磁流体和微波吸收剂等方面也具有广阔的应用前景。这些应用都是由于磁性氧化铁纳米微粒具有尺寸小、比表面积大、表面活性高以及在外磁场作用下快速响应等优良特性。因此，影响磁性氧化铁纳米微粒使用效果的两个关键因素是纳米微粒本身的磁性能及其表面修饰后的表面性质和磁性能。而磁性氧化铁纳米微粒的形貌、尺寸和结晶情况是影响其磁性能的重要因素。目前，人们对球形磁性氧化铁纳米微粒的制备和表面修饰研究得较多，而对于其它形状的磁性氧化铁微粒（如纳米棒，纳米片等）的制备和表面修饰的研究却为数不多。本文制备了不同形貌的磁性氧化铁纳米微粒，并对它们的表面进行了化学修饰。具体内容如下：（一）在水热条件下，通过加入表面活性剂，蛋白胨和淀粉等不同的辅助剂分别制备了磁性氧化铁纳米微粒，采用TEM、XRD、FT-IR和TGA等测试手段对合成的样品的形貌粒径和结构进行了表征。研究了不同反应温度、反应时间、和加入的辅助剂的量等因素对样品形貌、尺寸和结晶性的影响，探索出合成形貌规则、尺寸均匀的颗粒状、六角片状和棒状的磁性氧化铁纳米晶的最佳实验条件。实验结果表明表面活性剂、蛋白胨和淀粉在分别制备磁性Fe₃O₄纳米微粒，γ-Fe₂O₃纳米片和Fe₃O₄纳米棒的过程中，对样品的形貌和尺寸控制起着关键性的作用。另外，本文对合成得到的片状γ-Fe₂O₃和棒状Fe₃O₄纳米微粒样品形成的可能的机理进行了初步的探讨。（二）借助VSM对合成的样品的磁性能进行了表征。VSM测试结果表明，样品均具有室温铁磁性且样品的形貌和粒径对样品的磁性能有很大的影响。Fe₃O₄纳米微粒、Fe₃O₄纳米棒和γ-Fe₂O₃纳米片的饱和磁化强度要比相应体材料的饱和磁化强度小很多，而Fe₃O₄纳米棒的饱和磁化强度比颗粒状Fe₃O₄纳米微粒的要小，这可能是由于晶体的小尺寸效应和形状各向异性的影响而导致的结果。（三）为了提高磁性氧化铁纳米微粒的稳定性，分散性和生物相容性，本文采用生物相容性高分子如壳聚糖、牛血清白蛋白和无机物如正硅酸乙酯，偏硅酸钠和KH-560等，不同的化学修饰方法分别对磁性γ-Fe₂O₃纳米片和Fe₃O₄纳米棒的表面进行了化学修饰，通过TEM、FT-IR、XRD和TGA等分析测试手段对表面修饰后的样品进行了表征，结果表明采用乳化交联法，成功制备了粒径分布均匀的磁性壳聚糖纳米微粒；采用戊二醛交联法制备了牛血清白蛋白包覆的磁性纳米微粒；采用正硅酸乙酯，偏硅酸钠或KH-560修饰后，在γ-Fe₂O₃纳米片和Fe₃O₄纳米棒的表面包覆上SiO₂。通过VSM对表面修饰前后样品的磁性能进行了表征，表面修饰后样品的磁性能明显下降，这主要是由于修饰后的样品中磁性成份的含量降低，“稀释效应”导致样品整体的磁性能下降。虽然样品整体磁性能下降，但仍然有磁响应性。总之，本论文在水热条件下合成了不同形貌的磁性氧化铁纳米微粒并对合成的磁性氧化铁纳米微粒的的表面进行了化学修饰，我们的工作丰富了磁性氧化铁纳米微粒的制备方法，而且为磁性氧化铁纳米微粒在生物、医药等方面的应用提供了基础研究。更多还原

【Abstract】 With the development of nano-technology, magnetic ferric oxide nanoparticles arewidely studied for their application in biomedical field such as cell separation,enzyme immobilization, immunoassay, drug delivery, DNA separation and so on. Inaddition, magnetic ferric oxide nanoparticles are also widely used as magneticmaterials for information storage, catalyst, magnetic fluids, microwave absorbent et al.Their application is due to the magnetic ferric oxide nanoparticles possessing someexcellent characteristics, such as small size, great specific surface area, high surfaceactivity and magnetically responsive, and the morphology, size and crystal are theimportant factors to the magnetization of magnetic nanoparticles. So far, sphericalmagnetic ferric oxide nanoparticles have been widely synthesized and surfacemodified, while little work on synthesis or surface modification of ferric oxidenanorods or nanoplates has been done. In this thesis, the magnetic ferric oxidenanoparticles with different morphologies and sizes were synthesized and surfacemodified. The main content of the thesis is as follows:In this thesis, magnetic ferric oxide （Fe₃O₄,γ-Fe₂O₃） nanoparticles with welldispersion and regular morphology have been successfully synthesized by usingsurfactants, peptone, starch as an additive respectively under hydrothermal condition.The X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fouriertransform infrared spectrometer （FT-IR）, thermogravimetric analysis （TGA） andvibrating sample magnetometer （VSM） techniques were used to characterize theas-synthesized magnetic nanoparticles for their structure, shape and magneticproperties. In the experiments, the influences of the reaction temperature, reactiontime and mass of the additive on the products were intensively studied and theappropriate reaction conditions were determined. The results of our experimentsindicated that the additive played a critical role in the formation of magnetic ferricoxide （Fe₃O₄,γ-Fe₂O₃） nanoparticles with different morphologies. The possiblemechanisms for the formation of maghemite （γ-Fe₂O₃） nanoplates, magnetite （Fe₃O₄）nanorods were also discussed. The magnetic properties of the synthesized samples were characterized by VSM.The results reveal that the samples show ferromagnetic behavior at room temperatureand the magnetization has been much effected by the morphology, size of the samples.The values of saturated magnetization at 300 K of the as-synthesized magnetite（Fe₃O₄） nanoparticles, maghemite （γ-Fe₂O₃） nanoplates, magnetite （Fe₃O₄） nanorodsare lower than that of the corresponding bulk materials. Also the saturatedmagnetization of magnetite （Fe₃O₄） nanorods is lower than that of magnetite （Fe₃O₄）nanoparticles. This is mainly because of the small size effect and shape anisotropy.In order to improve the stability, dispersivity and biocompatibility of magneticferric oxide nanoparticles, maghemite （γ-Fe₂O₃） nanoplates and magnetite （Fe₃O₄）nanorods were surface modified by biocompatible polymer, such as chitosan, bovineserum albumin（BSA） and inorganic molecules, such as TEOS, Na₂SiO₃, KH-560. TheTEM, FT-IR, XRD, TGA and VSM were used to characterize the surface-modifiedsamples, and the results show that magnetic chitosan nanoparticles were successfullyprepared by the suspension cross-linking technique; BSA enwrapped magneticnanoparticles were prepared by the glutaraldehyde cross-linking technique; SiO₂ weresuccessfully coated on magnetic ferric oxide nanoparticles after surface modificationby TEOS, Na₂SiO₃ and KH-560. The values of saturated magnetization of magneticiron oxide nanoparticles after surface modification decreased apparently because ofthe "dilute effect". The magnetization of the samples decreased, while they are stillmagnetically responsive.In this thesis, different morphologies of the ferric oxide nanoparticles weresynthesized under hydrothermal condition, and the as-synthesized maghemite（γ-Fe₂O₃） nanoplates and magnetite （Fe₃O₄） nanorods were surface modified. Ourwork enriches the preparations of magnetic ferric oxide nanoparticles, and providesbasic research for the application of magnetic ferric oxide in biomedical field.更多还原