高温多元醇法制备超顺磁CoFe_2O_4纳米颗粒磁共振造影剂

High Temperature Polyol Synthesis of Superparamagnetic CoFe_2O_4 Nanoparticles for Magnetic Resonance Imaging Contrast Agents

以FeCl3.6H2O、CoCl2.6H2O和HOOC-PEG-COOH为反应物,利用高温多元醇法制备了核心粒径为5～10nm的超顺磁CoFe2O4纳米颗粒,样品在水溶液中具有良好分散性.通过改变修饰剂的种类和用量、反应温度及反应时间可以对纳米颗粒的尺寸、水中分散性及磁性能产生影响.研究表明:选用带有强极性基团的修饰剂,增加修饰剂的用量,提高反应温度和延长反应时间,可以增大颗粒的尺寸,改善颗粒的分散性,窄化粒径分布.实验获得的最佳生长条件为:金属盐总量与修饰剂质量比为1:10,在210～220℃之间反应2h.磁性能研究表明所得样品在室温下具有超顺磁性,其饱和磁化强度与尺寸有关.

The superparamagnetic CoFe2O4 nanoparticles with core size of 510nm were prepared by high temperature polyol process using FeCl3·6H2O, CoCl2·6H2O and HOOC-PEG-COOH as reactants. The samples had good monodispersibility in aqueous solution. Moreover, the influences of reaction conditions such as varieties of modification agents and their amounts, reaction temperature and time on the size, dispersibility and magnetic properties of CoFe2O4 nanoparticles were investigated. The results indicate that choosing the modification agent with strong polar group, increasing the amount of modification agent, elevating reaction temperature and extending reaction time are beneficial to obtain samples with larger particle size, better waterdispersibility and narrower size distribution. The optimum reaction condition is determined as follows, the weight ratio of metal source to HOOC-PEG-COOH is 1∶10, reaction temperature is 210-220℃ and reaction time is 2h. Magnetic analysis shows that all the samples manifest a well-defined superparamagnetic behavior at room temperature. The larger the particle sizeis is, the higher saturation magnetizationis is.