Conductance of ion channels and nanopores with charged walls: a toy model

TL;DR

This paper presents a simplified model demonstrating how immobile charges on the walls of ion channels and nanopores significantly reduce electrostatic barriers, thereby enhancing ion conductance.

Contribution

It introduces a toy model showing that even low concentrations of wall charges can nearly eliminate electrostatic barriers in ion channels.

Findings

Wall charges drastically reduce electrostatic barriers.

Barrier vanishes at relatively low wall charge concentrations.

Enhanced ion conductance due to wall charge effects.

Abstract

We consider ion transport through protein ion channels in lipid membranes and water-filled nanopores in silicon films. It is known that, due to the large ratio of dielectric constants of water and the surrounding material, an ion placed inside the channel faces a large electrostatic self-energy barrier. The barrier leads to an exponentially large resistance of the channel. We study reduction of the electrostatic barrier by immobile charges located on the internal walls of the channel. We show that the barrier practically vanishes already at relatively small concentration of wall charges.