Ge Jianping, Hu Yongxing, Biasini Maurizio, Dong Chungli, Guo Jinghua, Beyermann Ward P, Yin Yadong
Department of Chemistry, University of California, Riverside, CA 92521, USA.
Chemistry. 2007;13(25):7153-61. doi: 10.1002/chem.200700375.
A high-temperature solution-phase hydrolysis approach has been developed for the synthesis of colloidal magnetite nanocrystals with well-controlled size and size distribution, high crystallinity, and high water solubility. The synthesis was accomplished by the hydrolysis and reduction of iron(III) cations in diethylene glycol with a rapidly injected solution of sodium hydroxide at an elevated temperature. The high reaction temperature allows for control over size and size distribution and yields highly crystalline products. The superior water solubility is achieved by using a polyelectrolyte, that is, poly(acrylic acid) as the capping agent, the carboxylate groups of which partially bind to the nanocrystal surface and partially extend into the surrounding water. The direct synthesis of water-soluble nanocrystals eliminates the need for additional surface modification steps which are usually required for treating hydrophobic nanocrystals produced in nonpolar solvents through the widely recognized pyrolysis route. The abundant carboxylate groups on the nanocrystal surface allow further modifications, such as bioconjugation, as demonstrated by linking cysteamine to the particle surface. The monodisperse, highly water-soluble, superparamagnetic, and biocompatible magnetite nanocrystals should find immediate important biomedical applications.
已开发出一种高温溶液相水解方法，用于合成尺寸和尺寸分布可控、结晶度高且水溶性高的胶体磁铁矿纳米晶体。该合成是通过在高温下用快速注入的氢氧化钠溶液水解和还原二甘醇中的铁（III）阳离子来完成的。高反应温度有助于控制尺寸和尺寸分布，并产生高度结晶的产物。通过使用聚电解质，即聚丙烯酸作为封端剂来实现优异的水溶性，其羧基部分结合到纳米晶体表面，部分延伸到周围的水中。水溶性纳米晶体的直接合成消除了对额外表面改性步骤的需求，而这些步骤通常是通过广泛认可的热解路线处理在非极性溶剂中产生的疏水性纳米晶体所必需的。纳米晶体表面丰富的羧基允许进一步的修饰，如生物共轭，通过将半胱胺连接到颗粒表面来证明。单分散、高度水溶性、超顺磁性和生物相容性的磁铁矿纳米晶体应会立即在重要的生物医学应用中得到应用。
