Controlling polymer translocation and ion transport via charge correlations

TL;DR

This paper introduces a correlation-corrected transport theory to accurately predict ionic and polymer transport in nanopores, explaining experimental phenomena and enabling improved DNA sequencing techniques.

Contribution

The study develops a novel correlation-corrected model that accounts for surface polarization effects and charge correlations, extending beyond mean-field electrostatics.

Findings

Explains low KCl conductivity in alpha-Hemolysin pores.

Shows charge inversion with multivalent ions can halt polymer translocation.

Demonstrates potential for enhancing DNA sequencing accuracy.

Abstract

We develop a correlation-corrected transport theory in order to predict ionic and polymer transport properties of membrane nanopores in physical conditions where mean-field electrostatics breaks down. The experimentally observed low KCl conductivity of open alpha-Hemolysin pores is quantitatively explained by the presence of surface polarization effects. Upon the penetration of a DNA molecule into the pore, these polarization forces combined with the electroneutrality of DNA sets a lower boundary for the ionic current, explaining the weak salt dependence of blocked pore conductivities at dilute ion concentrations. The addition of multivalent counterions into the solution results in the reversal of the polymer charge and the direction of the electroosmotic flow. With trivalent spermidine or quadrivalent spermine molecules, the charge inversion is strong enough to stop the translocation of the polymer and to reverse its motion. This mechanism can be used efficiently in translocation experiments in order to improve the accuracy of DNA sequencing by minimizing the translocation velocity of the polymer.