【作者】 黄景科；

【导师】 贺全国；

【作者基本信息】 湖南工业大学 ， 生物医学工程， 2009， 硕士

【摘要】 磁性载体的生物传感技术在生物医学的许多领域展现出广阔的应用前景。磁性纳米粒子除了对外加磁场具有响应性外,磁性粒子的另一特点是通过功能化修饰使其表面带有不同的功能基团,通过修饰在其表面的功能化活性基团可连接抗体、抗原、核酸及寡核昔酸等生物活性物质。因此,以金等贵金属功能化的磁性纳米粒子为载体在免疫检测、核酸的纯化与分离、靶向载药、固定化酶、细胞分离等生物医学领域得到了广泛的应用。本文的主旨在于以磁性纳米颗粒为核,在其表面包覆一层具有生物相容性的贵金属原子,从而制备出具有核壳结构的纳米复合颗粒。而作为磁性纳米材料的一个重要组成部分,磁性γ-Fe₂O₃纳米颗粒也有着广泛的应用前景。本论文正是基于以上考虑,选择了“复合金磁γ-Fe₂O₃纳米粒子的制备研究”作为研究方向,从以下几个方面开展了工作:1、以改进的共沉淀法制备的Fe3O4为前驱,采用高温氧化法制备了超顺磁性γ-Fe₂O₃纳米粉体,对其形貌、结构、磁学性能进行了考察,并考察了不同的氧化温度对粒子晶型结构的影响。主要取得以下结果:用高温氧化法制备了粒径为20nm左右的磁性γ-Fe₂O₃纳米粒子。在高温氧化过程中考察了不同的氧化温度对粒子结构的影响,随着氧化温度的升高,前驱体粒子Fe3O4逐渐转化为γ-Fe₂O₃,继续提高温度则产物转变为α-Fe₂O₃。2、合成了氨基功能化和巯基功能化两种表面功能化的磁性γ-Fe₂O₃纳米粒子,并对其形貌、结构和磁学性能进行了比较研究。分别采用3-氨丙基三乙氧基硅烷（APTES）和3-巯丙基三乙氧基硅烷（MPTES）将γ-Fe₂O₃纳米粒子表面修饰上氨基（-NH₂）官能团和巯基（-SH）官能团,从而获得了表面功能化的磁性γ-Fe₂O₃纳米粒子。氨基功能化和巯基功能化后的磁性粒子粒径略有增加,较好的保留了原始结构和磁性特征。3、提出了基于超声化学法制备γ-Fe₂O₃/Au和自组装法制备Gold-Mag两种金包覆的磁性复合纳米粒子的方法,并对这些金磁纳米粒子的形貌、结构和磁学性能进行了研究,主要取得如下结果:1)采用超声化学法制备的γ-Fe₂O₃/Au复合粒子在常温下表现出较好的顺磁性特征,并具有较为稳定的光学吸收特点,并且其饱和磁化强度可以达到80 emu/g以上,为其在生物医学领域中的应用奠定了基础。2)采用自组装法制备的Gold-Mag金磁复合纳米粒子,结果显示自组装金磁粒子具有更好的磁响应性,且兼有磁性纳米粒子和胶体金的特性。更多还原

【Abstract】 The magnetic carrier-based biosensor technique displays widely promising applications in many fields of biomedical engineering. Magnetic nanoparticles （MNPs） could respond simultaneously as the magnetic field is applied, besides, the MNPs can be modified with different bioactivators such as antibody, antigen, nucleic acid, oligonucleotide and so on. Therefore, the noble such as gold functionalized MNPs are used as carrier and then can be widely applied in immunoassay, purification and separation of nucleic acid, target delivery, enzyme immobilization, cell separation and so on.This thesis reported that the MNPs were used as carrier core, then biocompatibile noble mental gold were modified onto the MNPs for preparing gold-coated nanocomposites. As an important component part of MNPs, Maghemite （γ-Fe₂O₃） MNPs have widely promising applications. Considering the above reasons, our research focused on the preparation of maghemite-based nanocomposites. The thesis includes the following parts:Charpter 1 Magnetic Fe3O4 nanopowders were prepared by modified chemical coprecipitation and then were used as precursors, the maghemite nanopowders were prepared under high temperature oxidation. The properties and structure of maghemite were thoroughly studied under different oxidation temperature. The results revealed that the nanopowders were of average diameter ca.20 nm. Moreover, as the oxidation temperature increases, the precursor nanoparticles gradully changed into maghemite （γ-Fe₂O₃） under proper temperature, and finally becameα-Fe₂O₃ if temperature continues to increase.Charpter 2 Reported silane tailoring of maghemite nanoparticles to obtain amino-coated and thiolated MNPs via 3-aminopropyltriethy loxysilane （APTES） and mercaptopropyltriethoxysilane （MPTES） modification, respectively. Corresponding structure and magnetics properties of the functinalized maghemite were thoroughly studied. The results prove that the surface functionalized MNPs have a slight dimensional increase in average diameter, and retain almost original structures and saturation magnetization （Ms） of parent maghemite.Chapter 3 Described two gold mental functionalized MNPs （γ-Fe₂O₃/Au and Gold-Mag） by sonochemical synthesis and self-assembly methods, respectively. Meanwhile, the structure and magnetic properties of the nanocomposites were investigated. Some results were as follows:1)γ-Fe₂O₃/Au nanocomposites presented paramagnetism at room temperature, and possessed a very high Ms of about 80 emu·g-1. In addition,γ-Fe₂O₃/Au nanoparticles had a steady optical absorption. These combined-properties can readily extend the nanocomposites to further biochemical applications.2) Gold-Mag nanocomposites particles were prepared by self-assembly. The nanoparticles demonstrated well magnetic response and had the similar optical properties of colloidal gold.更多还原