配体交换法制备水中高分散稳定性的多羧基修饰Fe3O4纳米颗粒

采用油相高温分解法制备了粒径可控且单分散的油溶性Fe3O4磁性纳米粒子(MNPs-OA), 并通过配体交换对其表面进行了亲水性修饰, 制备了柠檬酸(CA)、 N-(三甲氧基硅丙基)乙二胺三乙酸钠(SiCOOH)、 丁烷四羧酸(BTCA)和乙二胺四乙酸 (EDTA)四钠4种多羧基配体修饰的水溶性Fe3O4磁性纳米粒子(MNPs-CA, MNPs-SiCOOH, MNPs-BTCA 和MNPs-EDTA), 其中首次选用四羧基配体BTCA和EDTA四钠来修饰Fe3O4磁性纳米粒子(MNPs). 对油溶性MNPs和4种水溶性MNPs的形貌、 结构、 化学组成和磁性能进行了表征, 并对4种多羧基配体修饰的水溶性MNPs在水相中的稳定性和分散性进行了表征. 结果表明, 所得MNPs的平均粒径为15 nm, 具有超顺磁性, 配体交换后的水溶性MNPs具有良好的亲水性, 并在弱酸～碱性很宽的pH范围内具备良好的分散稳定性. 此类多羧基修饰的水溶性MNPs可与适当的阳离子聚电解质进行组装, 从而得到在磁靶向载体和磁共振造影(MRI)显影中具有良好应用前景的磁性自组装微囊.

Synthesis of Polycarboxylic Ligand Capped Fe3O4 Nanoparticles with Excellent Water-dispersibility via a Ligand-exchange Approach

Monodispersed magnetic Fe3O4 nanoparticles(MNPs) capped with oleic acid(MNPs-OA) were synthesized through a thermal decomposition method. On this basis, four kinds of water-soluble Fe3O4 nano-particles(MNPs-CA, MNPs-SiCOOH, MNPs-BTCA and MNPs-EDTA) capped with four different polycarboxylic ligands, i.e., citric acid(CA), n-(trimethoxysilylpropyl)ethylene diamine triacetic acid(SiCOOH) trisodium salt, butane tetracarboxylic acid(BTCA) and ethylenediaminetetraacetic acid(EDTA) tetrasodium salt, were prepared via a ligand exchange approach. Among the four ligands, the BTCA and EDTA tetrasodium salt with four carboxy groups were first chosen to cap Fe3O4 nanoparticles. The morphology, structure, chemical composition and magnetic properties of the four water-dispersible MNPs were characterized by transmission electron microscope(TEM), X-ray diffractometer(XRD), vibrating sample magnetometer(VSM), Fourier transform infrared spectrometer(FTIR) and thermal gravimetric analyzer(TGA). The water-dispersibility and suface potential of four water-soluble MNPs in their aqueous solutions were also characterized by UV-visible spectrophotometer(UV-Vis) and Malvern Zetaszier analyzer, respectively. The results show that the resultant 15 nm Fe3O4 nanoparticles possess narrow size distribution and superparamagnetism. In addition, the polycarboxylic ligand capped MNPs display excellent dispersibility in their aqueous solutions. By the co-assembly of these MNPs and polyelectrolyte, we fabricated magnetic microcapsules. The microcapsules are of great potential in biomedical fields owing to the magnetic responsivity and MRI imaging capability of MNPs.