Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Langmuir. 2010 Dec 7;26(23):18491-8. doi: 10.1021/la103564p. Epub 2010 Nov 11.
A facile solution process for the preparation of anisotropic silica nanoparticles (ASNPs) is presented. ASNPs are prepared via controlled self-assembly of spherical silica seeds (22 nm) in alcohol-water mixed media, followed by their in situ fixation and overgrowth with tetraethoxysilane (TEOS). Ethanol and L-arginine (Arg) are used to modify the dielectric constant and ionic strength of the reaction media, by which seed assembly is controlled through the adjustment of electrostatic interaction. Ethanol and Arg also serve as a cosolvent and a catalyst for hydrolysis and condensation of TEOS, respectively, which enables us to produce ASNPs in a simple one-pot process. In addition to ASNPs with wormlike structures, different kinds of NPs (bimodal spherical NPs, monodisperse spherical NPs, and spherical aggregates) have also been obtained by changing the concentrations of ethanol and Arg. The length, thickness, or both of ASNPs are controlled systematically by varying the concentrations of Arg, seed NPs, and TEOS. Other alcoholic cosolvents, such as methanol, 1-propanol, 2-propanol, and t-butanol, are also effective to give ASNPs when the dielectric constant of the alcohol-water mixed media is properly adjusted, showing the versatility of the present method.
一种制备各向异性二氧化硅纳米粒子（ASNPs）的简便方法。通过在醇-水混合介质中控制球形二氧化硅种子（22nm）的自组装，然后原位固定和用四乙氧基硅烷（TEOS）进行外延生长，制备 ASNPs。乙醇和 L-精氨酸（Arg）用于调节反应介质的介电常数和离子强度，通过调整静电相互作用来控制种子组装。乙醇和 Arg 还分别用作 TEOS 水解和缩合的共溶剂和催化剂，这使我们能够在简单的一锅法中制备 ASNPs。除了具有蠕虫状结构的 ASNPs 外，通过改变乙醇和 Arg 的浓度，还可以得到不同种类的 NPs（双峰球形 NPs、单分散球形 NPs 和球形聚集体）。通过改变 Arg、种子 NPs 和 TEOS 的浓度，可以系统地控制 ASNPs 的长度、厚度或两者。当适当调整醇-水混合介质的介电常数时，其他醇类共溶剂，如甲醇、1-丙醇、2-丙醇和叔丁醇，也能有效地得到 ASNPs，显示出该方法的通用性。
