# Controlling Polymer Capture and Translocation by Electrostatic Polymer-Pore Interactions

## TL;DR

This paper models electrostatic interactions in polymer translocation through nanopores, revealing how salt concentration, membrane charge, and pore size influence capture probability and translocation time, aiding experimental control.

## Contribution

It introduces a coupled electrohydrodynamic and Smoluchowski model to analyze electrostatic barriers in polymer translocation, highlighting the role of salt and pore parameters.

## Key findings

- Existence of a salt concentration maximizing capture probability.
- Translocation time increases exponentially with membrane charge.
- Translocation time decreases exponentially with pore radius and salt concentration.

## Abstract

Polymer translocation experiments typically involve anionic polyelectrolytes such as DNA molecules driven through negatively charged nanopores. Quantitative modelling 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 occur, 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 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.