Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 10617.
J Phys Chem B. 2012 Oct 18;116(41):12626-32. doi: 10.1021/jp305473s. Epub 2012 Oct 8.
We modeled the electrophoresis of a soft cylindrical particle comprising a rigid core and a polyelectrolyte layer along the axis of a long, cylindrical pore, and the applicability of the model proposed is verified by the experimental data available in the literature. Previous analysis is extended to the case where the effects of double-layer polarization (DLP) and electroosmotic flow (EOF) can be significant. We show that the interaction between the particle's double layer and the pore, the competition between the effective charge density and the local electric field strength, and the presence of EOF yield interesting and significant results. For example, if EOF is absent, the particle mobility as the bulk salt concentration varies depends highly on the amount of fixed charge of its polyelectrolyte layer: if that amount is small, the mobility decreases monotonically with increasing bulk salt concentration, and if that amount is large, then the mobility shows a local maximum. At a high bulk salt concentration, the longer the particle the larger is its mobility, that trend is reversed if it is low. That local minimum vanishes when the boundary effect is important. If the pore is positively charged, a positively charged particle can be driven to the direction opposite to that of the applied electric field. These provide necessary information for the design of electrophoresis devices.
我们对一个软圆柱颗粒在长圆柱形孔的轴线上电泳进行建模，该颗粒由刚性核心和聚电解质层组成，并通过文献中的实验数据验证了所提出模型的适用性。我们将之前的分析扩展到可以显著影响双层极化（DLP）和电渗流（EOF）的情况。结果表明，颗粒的双电层与孔之间的相互作用、有效电荷密度与局部电场强度之间的竞争以及电渗流的存在会产生有趣且重要的结果。例如，如果不存在电渗流，颗粒的迁移率随本体盐浓度的变化高度依赖于其聚电解质层的固定电荷数量：如果该数量较小，迁移率随本体盐浓度的增加而单调下降，如果该数量较大，则迁移率会出现局部最大值。在高本体盐浓度下，颗粒越长其迁移率越大，如果浓度较低则反之。当边界效应很重要时，局部最小值会消失。如果孔带正电荷，带正电荷的颗粒会被驱动到与施加电场相反的方向。这些结果为电泳设备的设计提供了必要的信息。
