Self-energy limited ion transport in sub-nanometer channels

TL;DR

This study investigates how ion transport through sub-nanometer channels is limited by self-energy barriers, affecting DNA translocation and current-voltage behavior, with implications for nanopore sensing.

Contribution

It provides experimental evidence linking ion electrostatic self-energy barriers to transport limitations in sub-nanometer channels, supported by a theoretical model.

Findings

Strong current blockage observed during DNA passage

Current exhibits weak super-linear growth with voltage

Current shows a minimum as a function of ionic strength C

Abstract

The current-voltage characteristics of the alpha-Hemolysin protein pore during the passage of single-stranded DNA under varying ionic strength, C, are studied experimentally. We observe strong blockage of the current, weak super-linear growth of the current as a function of voltage, and a minimum of the current as a function of C. These observations are interpreted as the result of the ion electrostatic self-energy barrier originating from the large difference in the dielectric constants of water and the lipid bilayer. The dependence of DNA capture rate on C also agrees with our model.