【作者】 许雪飞；

【导师】 薛德胜；

【作者基本信息】 兰州大学 ， 凝聚态物理， 2010， 博士

【摘要】 近年来,纳米生物技术作为一种涵盖了生物学、化学和物理学的综合性跨领域技术,涉及到生物医药学等各领域方面的研究内容,迄今已取得了非常令人鼓舞的成就,并使得纳米生物医学技术成为纳米科技领域最引人注目、最有生命力的发展方向之一。其中,基于磁性纳米颗粒磁热效应的磁热疗在肿瘤的早期诊断与治疗中的应用,也受到了研究者的广泛关注,并取得了一定的研究成果。但是,对于磁性材料的选择仍存在较多争议,并且在磁热效应的机制研究中仍然缺乏一个令人信服的理论结果。本论文的主要工作是采用水热／溶剂热合成方法制备了多种粒径的表面氨基修饰的纳米Fe304颗粒与微球,对这些材料的性质与磁热效应进行了研究。主要内容和创新如下：一、采用单一制备方法水热法,通过工艺参数的调整与控制制备了10-100 nm不同直径的单分散的单晶Fe304颗粒。对其性质进行了表征与研究,发现表面氨基修饰使磁颗粒具有良好的亲水性；颗粒体系矫顽力以及有效各向异性等随尺寸变化的趋势在常温下满足D3/2关系,低温下满足D6关系,与随机各向异性模型(RAM)理论吻合。二、水热／溶剂热法一次性合成由不同粒径与形貌Fe304颗粒组成的微球,对微球生成机理进行了讨论与研究,对比研究了30 nm和50 nm颗粒以及由这两种尺寸球形颗粒组成的微球的磁热性能,发现微球的主要磁性能取决于其组成颗粒的尺寸与形貌,如具有相似的饱和磁化强度和矫顽力,但是微球的SAR值则小于相应的颗粒。磁滞损耗对颗粒与微球SAR的贡献都较小。三、系统研究了颗粒与微球的磁热效应。研究发现被琼脂凝胶固定住的颗粒体系与原始状态具有相同的磁热效应,排除了布朗弛豫的影响；通过磁滞损耗理论模型研究发现材料的磁热能力不完全依赖于其基本磁性能；磁热效应具有明显的尺寸依赖性,采用有效各向异性理论推导并修正了在超顺磁-单畴转变尺寸范围内颗粒的磁热机制,发现在此尺度范围内的损耗机制主要是奈尔弛豫过程,实验结果与理论模型基本吻合。四、对磁流体磁分离过程中高梯度磁场对颗粒／微球体系尺寸分布的影响进行了理论模拟,构建了尺寸分布变化模型并进行了实验验证。模拟发现通过高梯度磁场分离处理后可显著提高体系的尺寸分散性,与实验结果比较吻合。对磁分级的应用与研究具有指导意义。更多还原

【Abstract】 In recent years, nano-biotechnology as a cross-cutting technology covering biology, chemistry and physics with relating to bio-medicine and other fields have been attracted much attention and become one of the most eye-catching and viable field of nanotechnologies. The applications of magnetic hyperthermia used in early diagnosis and treatment of cancers which based on the magnetocaloric effect of magnetic nanoparticles have been widely researched, and some results have already been made. However, there are many disputes on the choosing of magnetic materials and there is also no convincing theoretical result. In this thesis, the main work is to prepare amino-modified Fe3O4 nanoparticles and microspheres with a wide range particle size and to make some investigation on the magnetism and magnetocaloric effect of materials. Some main contents and innovations in this paper are listed in the following:1. Monodisperse Fe3O4 particles with different diameter form 10 to 100 nm using a unitary method have been fabricated by adjustment and control of process parameters, and their characters and magnetocaloric effect under alternating magnetic field have been researched. Surface amino-modified makes magnetic particles a good hydrophilicity. And the magnetic properties of particle system such as coercive force and effective anisotropy are in line with the Random Anisotropy Model theory.2. Microspheres in different sizes and morphologies have been fabricated by hydrothermal/Solvothermal. The synthesis mechanism of the microspheres has been studied. The magnetic system and thermal performance between particles and the magnetic microspheres has been comparatively studied, too. It’s found that the main magnetism lies on the sizes and morphologies of particles.3. The magnetocaloric property of the particles and the microspheres has been studied. It is found that there is no evident difference between the systems both in dispersive state and in hydrogel state, which obviates the effect of Brownian relaxation. It is also found that the magnetocaloric ability of the materials does not fully depend on their basic magnetic character by contrasting to the result of the hysteresis loss theory model. Magnetocaloric effect has an obvious dependence on the size of the particles. The magnetocaloric mechanism of the particles with size range in superparamagnetic to single domain transition length has been investigated by modifying the relaxation model with Random Anisotropy Model theory. The experiment results are in agreement with this model.4. The thesis contents some theoretical simulation about influence to particles and microspheres caused by high gradient magnetic fields, and also build a size-changing model with experimental verification. The simulation indicates that after high gradient magnetic separation the size dispersion significantly increases which agreements with experimental results. And this shows some guidance of the application and study of magnetic classification.更多还原