Invariant ionic conductance in an atomically thin polar nanopore

TL;DR

This study demonstrates invariant ionic conductance in atomically thin MoSSe nanopores across a wide salt concentration range, revealing a novel conductance scaling law influenced by the material's dipole properties.

Contribution

It uncovers a unique conductance behavior in polar monolayer nanopores, driven by intrinsic dipole effects, unlike traditional models.

Findings

Ionic conductance remains constant over six orders of magnitude in salt concentration.

Molecular dynamics simulations show dipole-modulated dielectric effects are key.

The conductance behavior resembles saturation phenomena in biological membranes.

Abstract

Ion channels regulate many essential properties of biological cells, especially the membrane potential. Despite decades of efforts on artificial channels, it remains a great challenge to mimic the dipole potential-an indispensable constituent of the membrane potential, due to its angstrom-scale characteristic length. Here, we explore nanopores in monolayer molybdenum sulfide selenide (MoSSe) considering its intrinsic dipole and atomic thickness. Remarkably, an invariant ionic conductance was observed over salt concentrations spanning six orders of magnitude, distinct from all known conductance-concentration scaling laws and reminiscent of the current saturation in cell membranes at high concentrations. Molecular dynamics simulations revealed the fundamental role of the dipole-modulated dielectric properties of nanoconfined water. Our findings highlight an exotic conductance scaling law and open up a novel avenue for controlling ion transport in unprecedented ways.