Qian Shizhi, Joo Sang W, Hou Wen-Sheng, Zhao Xuxin
Department of Mechanical Engineering, University of Nevada Las Vegas, Las Vegas, Nevada 89154-4027,USA.
Langmuir. 2008 May 20;24(10):5332-40. doi: 10.1021/la703590p. Epub 2008 Apr 10.
The electrophoretic motion of a spherical nanoparticle, subject to an axial electric field in a nanotube filled with an electrolyte solution, has been investigated using a continuum theory, which consists of the Nernst-Planck equations for the ionic concentrations, the Poisson equation for the electric potential in the solution, and the Stokes equation for the hydrodynamic field. In particular, the effects of nonuniform surface charge distributions around the nanoparticle on its axial electrophoretic motion are examined with changes in the bulk electrolyte concentration and the surface charge of the tube's wall. A particle with a nonuniform charge distribution is shown to induce a corresponding complex ionic concentration field, which in turn influences the electric field and the fluid motion surrounding the particle and thus its electrophoretic velocity. As a result, contrary to the relatively simple dynamics of a particle with a uniform surface charge, dominated by the irradiating electrostatic force, that with a nonuniform surface charge distribution shows various intriguing behaviors due to the additional interplay of the nonuniform electro-osmotic effects.
利用一种连续介质理论，研究了在充满电解质溶液的纳米管中，受轴向电场作用的球形纳米颗粒的电泳运动。该理论由离子浓度的能斯特 - 普朗克方程、溶液中电势的泊松方程以及流体动力学场的斯托克斯方程组成。特别地，随着本体电解质浓度和管壁表面电荷的变化，研究了纳米颗粒周围非均匀表面电荷分布对其轴向电泳运动的影响。结果表明，具有非均匀电荷分布的颗粒会诱导出相应的复杂离子浓度场，进而影响颗粒周围的电场和流体运动，从而影响其电泳速度。因此，与表面电荷均匀的颗粒相对简单的动力学（主要由辐射静电力主导）不同，具有非均匀表面电荷分布的颗粒由于非均匀电渗效应的额外相互作用而表现出各种有趣的行为。
