Polymer translocation experiments typically involve anionic polyelectrolytes such as DNA molecules driven through negatively charged nanopores. Quantitative modeling of polymer capture to the nanopore followed by translocation therefore necessitates the consideration of the electrostatic barrier resulting from like-charge polymer-pore interactions. To this end, in this work we couple mean-field level electrohydrodynamic equations with the Smoluchowski formalism to characterize the interplay between the electrostatic barrier, the electrophoretic drift, and the electro-osmotic liquid flow. In particular, we find that due to distinct ion density regimes where the salt screening of the drift and barrier effects occurs, there exists a characteristic salt concentration maximizing the probability of barrier-limited polymer capture into the pore. We also show that in the barrier-dominated regime, the polymer translocation time τ increases exponentially with the membrane charge and decays exponentially fast with the pore radius and the salt concentration. These results suggest that the alteration of these parameters in the barrier-driven regime can be an efficient way to control the duration of the translocation process and facilitate more accurate measurements of the ionic current signal in the pore.

中文翻译：

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通过静电聚合物-孔相互作用控制聚合物的捕获和转运

聚合物移位实验通常涉及阴离子聚电解质，例如通过带负电荷的纳米孔驱动的DNA分子。因此，对聚合物捕获到纳米孔然后进行移位的定量建模需要考虑由电荷相同的聚合物-孔相互作用产生的静电势垒。为此，在这项工作中，我们将平均场级电流体动力学方程式与Smoluchowski形式主义结合起来，以表征静电势垒，电泳漂移和电渗流之间的相互作用。尤其是，我们发现，由于出现了对漂移和势垒效应进行盐筛选的独特的离子密度机制，因此存在一个特征性的盐浓度，可最大限度地提高受势垒限制的聚合物捕获到孔隙中的可能性。τ随膜电荷的增加呈指数增长，随孔隙半径和盐浓度的增加呈指数下降。这些结果表明在势垒驱动方案中这些参数的改变可以是控制易位过程的持续时间并有助于更准确地测量孔中离子电流信号的有效方法。