Electric-field-driven polymer entry into asymmetric nanoscale channels

TL;DR

This study combines theoretical analysis and molecular dynamics simulations to understand how electric fields influence the entry of charged polymers like DNA into asymmetric nanoscale channels, highlighting the roles of polymer length, electric field strength, and channel geometry.

Contribution

It provides a combined theoretical and simulation framework to analyze the electric-field-driven polymer entry into asymmetric nanoscale channels, emphasizing the effects of squeezing and lateral confinement.

Findings

The free-energy barrier depends on polymer length, electric field, and channel geometry.

Squeezing and lateral confinement significantly influence the barrier height.

Results align well with experimental data on polymer translocation.

Abstract

The electric-field-driven entry process of flexible charged polymers such as single stranded DNA (ssDNA) into asymmetric nanoscale channels such as alpha-hemolysin protein channel is studied theoretically and using molecular dynamics simulations. Dependence of the height of the free-energy barrier on the polymer length, the strength of the applied electric field and the channel entrance geometry is investigated. It is shown that the squeezing effect of the driving field on the polymer and the lateral confinement of the polymer before its entry to the channel crucially affect the barrier height and its dependence on the system parameters. The attempt frequency of the polymer for passing the channel is also discussed. Our theoretical and simulation results support each other and describe related data sets of polymer translocation experiments through the alpha-hemolysin protein channel reasonably well.