Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
Langmuir. 2013 Jun 11;29(23):7162-9. doi: 10.1021/la400946s. Epub 2013 May 30.
We consider the electrophoresis of a rigid sphere along the axis of a narrow cylindrical capillary; both are pH-regulated and zwitterionic. This extends available analyses in the literature to a more general and realistic case. Adopting a titanium oxide (TiO2) particle in a silicon dioxide (SiO2) capillary as an example, we examine the capillary radius, the solution pH, and the electrolyte concentration (or double-layer thickness) for their influences on the electrophoretic behavior of a particle. Because the pH solution is adjusted by HCl and NaOH, the presence of four kinds of ionic species, namely, H(+), OH(-), Na(+), and Cl(-), should be considered if NaCl is the background electrolyte. This also extends conventional electrophoresis analyses to the case of multiple ionic species. The interactions of the electroosmotic flow, the properties of the particle and the solution, and the capillary wall yield complicated electrophoretic behavior that can be regulated by the solution pH and the background electrolyte concentration. The results gathered are necessary for the future design of nanopore-based electrophoresis devices.
我们研究了刚性球体沿着狭窄圆柱形毛细管轴的电泳运动，其中毛细管和球体均为 pH 调节型两性离子。这将文献中现有的分析扩展到更一般和更现实的情况。我们以二氧化硅（SiO2）毛细管中的氧化钛（TiO2）颗粒为例，研究了毛细管半径、溶液 pH 值和电解质浓度（或双电层厚度）对颗粒电泳行为的影响。由于 pH 溶液是通过 HCl 和 NaOH 进行调节的，如果背景电解质是 NaCl，则应考虑四种离子种类，即 H(+)、OH(-)、Na(+) 和 Cl(-)。这也将传统的电泳分析扩展到多种离子种类的情况。电渗流、颗粒和溶液的特性以及毛细管壁的相互作用产生了复杂的电泳行为，可以通过溶液 pH 值和背景电解质浓度来调节。收集到的结果对于基于纳米孔的电泳设备的未来设计是必要的。
