【作者】 徐宏；

【导师】 古宏晨；

【作者基本信息】 上海交通大学 ， 材料学， 2008， 博士

【摘要】 纳米超顺磁性微球已在分离纯化、免疫检测、影像诊断、靶向给药与治疗等领域得到广泛应用。对于不同的生物医学应用,对磁性微球的表面与微观结构、物理化学性质以及微球的粒径大小与分布的要求均有较大差别。目前,超顺磁性复合微球的制备技术正朝着如何制备粒径更小(纳米尺度)、更均匀(单分散)、磁性物质含量更高(高饱和磁化强度)、表面与微观结构可根据应用需求进行设计与调控的方向发展。本论文就是针对上述发展趋势,提出创新的制备方法以及通过对其机理的深入研究,在纳米尺度实现集尺寸均一、磁性物质含量高等性能于一身的磁性功能复合微球的可控制备,并对其应用研究进行初探。本论文主要制备了粒径单分散、高饱和磁化强度聚合物磁性微球和高饱和磁化强度氧化硅磁微球,并将上述两类微球应用于核酸纯化与免疫层析检测研究。主要研究结果如下:(1)通过对传统细乳液聚合法制备磁性复合微球存在问题的分析,提出了一步细乳液法联合磁分级方法实现了高饱和磁化强度磁性微球的可控制备,得到的纳米磁性微球平均Fe3O4含量为73wt%以上,通过精密磁场分选,可得到数组单分散粒径的磁性复合微球。(2)提出了基于细乳液复合液滴成核的乳液聚合制备方法(双细乳液法),实现了粒径单分散、高饱和磁化强度磁性微球的可控制备。提出该方法的关键控制步骤是含有“纳米Fe3O4颗粒/辛烷”复合液滴的细乳液制备。通过对双细乳液聚合方法机理的研究,阐释影响磁性微球各项性能以及微观结构的重要因素,并发现Fe3+对聚合过程有阻聚作用。另外,磁细乳中辛烷以及交联共聚单体DVB对磁性复合微球形貌有影响,当磁细乳中辛烷含量较多时,得到的微球出现非常明显的非对称形貌,随着DVB用量的增加,微球微观偏析结构逐步改善。(3)在明晰双细乳制备方法机理的基础上,以核壳结构磁性复合微球为核,采用丙烯酸为共聚单体,制备表面具有羧基功能基团的磁性复合微球,羧基含量从0.27mmol/g~0.5mmol/g。(4)通过分析异相成核与生长对氧化硅磁微球形貌影响规律,提出了以磁性颗粒聚集体和聚合物磁微球为核,再结合改进溶胶-凝胶方法,可控制备了高饱和磁化强度、粒径单分散的多组分复合氧化硅磁微球。以Fe3O4/PS聚合物磁性微球为例,制备得到的氧化硅磁性微球在2nm氧化硅壳层厚度时,微球中纳米Fe3O4颗粒含量达70wt%。并通过研究改进的溶胶-凝胶反应的工艺条件,实现对氧化硅表面结构的调控。(5)在外磁场作用下,以Fe3O4/PS聚合物磁性微球为核可以制备得到稳定的氧化硅磁性链状结构,链状结构长度可以通过磁场强度进行调节;在磁场的调制作用下,得到的磁性微球可以形成超顺磁性的胶体光子晶体。(6)以本论文制备的氧化硅磁性微球为载体,研究氧化硅表面微观结构与核酸提取的相互关系,表明所合成的氧化硅微球可有效应用于核酸的提取;以表面功能化聚合物磁性微球为信号标记物,以hCG为模式待检分子,微球可有效地应用于定量磁性免疫层析检测系统。更多还原

【Abstract】 Superparamagnetic microspheres are widely used in bio or medical areas due to their unique properties. These applications include separation and purification of biomolecule, MRI contrast agent, hyperthermia, biosensor, and targeted drug delivery As specifically required for in vitro and in vivo tests, the current research aims have been focused on: (1) synthesizing mono-dispersed, nano-scale spheres for high sensitivity and efficiency (2) achieving high saturation magnetization for fast and sensitive magnetic signal control, manipulation, and detection, and (3) the surface structure could be designed according to application demands. Aimed at above tendency, this study developed a new controllable process to obtain mono dispersed, nano-scale, superparamagnetic magnetic microspheres with high saturation magnetization, and explore the reaction mechanism and nucleic acid extraction & immunoassay application.(1) Based on analysis of the process of magnetic microspheres by traditional miniemulsion polymerization, the mono-dispersed magnetite/polystyrene microspheres with high saturation magnetization were obtained by combining one-step miniemulsion polymerization and magnetic size sorting technique. The magnetite content of as-synthesized magnetic microspheres is 73wt%, and several groups of magnetic microspheres with mono-dispersed size could be obtained by magnetic size sorting technology.(2) The mono-dispersed magnetite/polystyrene microspheres with high saturation magnetization were obtained by miniemulsion nucleation/emulsion polymerization (double miniemulsion) method which was developed innovatively in this paper. Research results indicate that the preparation of“magnetite nanoparticles/octane”composite droplets is the key issue. Through investigation of double miniemulsion polymerization mechanism, the effect factors to the properties and microcosmic structure of microspheres were clarified, and we found Fe3+ on the surface of magnetite nanoparticles has inhibition effect. On the other hand, the microcomic structure of microspheres could be influenced in the present of octane. with the increase of the content of octane in ferrofluid, the dissymmetrical morphology are more easily be formed. The core/shell structure magnetic maicrospheres could be synthesized using DVB as copolymerization monomer, and dissymmetrical morphology disappeared with increase of DVB concentration.(3) Based on the mechanism of double polymerization, the carboxyl magnetic microspheres were prepared successfully using core/shell magnetic microspheres as core and crylic acid as copolymerization functional monomer. The carboxyl density of as-synthesized microspheres could be adjusted from 0.27mmol/g~0.5mmol/g.(4) Through analysis of effect of heterogeneous nucleation of silica on the morphology of composites microspheres, uniquely combining modified sol-gel technique and double miniemulsion polymerization & magnetite aggregates technique, the mono dispersed silica magnetic composite microspheres with high saturation magnetization were obtained. The silica shell thickness could be controlled by adding different amount TEOS. When we used Fe3O4/PS microspheres as core and the silica thickness is 2nm, the magnetite content of such silica magnetic microspheres is as high as 70wt%. on the other hands, Fe3O4/Silica composite nanospheres with different surface structure and morphology were also synthesized by changing reaction conditions of sol-gel method.(5) When the magnetic field was applied, the as-synthesied Fe3O4/PS/silica microspheres could become chain stable structure and the length of magnetic chian could be adjusted by changing magnetic intensity. The superparamagnetic colloid optical crystal could be formed in the present of applied magnetic field.(6) Nucleic acid extraction by the Fe3O4/Silica composite nanospheres were examined, and the relationship between surface structure and morphology of Fe3O4/Silica composite nanospheres was studied. Results shows that as-synthesized silica magnetic microsphere is a good candidate carriers for nucleic acid extraction. On the other hands, the carboxyl magnetic microsphere was used as signal label in quantitative magnetic lateral flow technique to carry out hCG detection. The results show that the as-synthesized carboxyl magnetic microsphere diameter of 130nm could be well applied in immunoassay.更多还原