Quantized ionic conductance in nanopores

TL;DR

This paper demonstrates that ionic conductance in nanopores can show quantized steps due to hydration layer disruptions, with potential for experimental observation, impacting biological and DNA sequencing technologies.

Contribution

The study reveals a novel quantization of ionic conductance caused by hydration layer breakup, supported by microscopic calculations and analysis of wave interference effects.

Findings

Conductance exhibits step-like nonlinearities as a function of pore radius.

Hydration layers break up, causing quantized conductance steps.

Water wave interference influences ion transport in nanopores.

Abstract

Ionic transport in nanopores is a fundamentally and technologically important problem in view of its occurrence in biological processes and its impact on novel DNA sequencing applications. Using microscopic calculations, here we show that ion transport may exhibit strong nonlinearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.