Driven polymer translocation into a channel: Iso-flux tension propagation theory and Langevin dynamics simulations

TL;DR

This study combines iso-flux tension propagation theory and Langevin dynamics simulations to analyze polymer translocation into channels, revealing force scaling behaviors and the impact of channel width on translocation dynamics.

Contribution

The paper introduces a combined theoretical and simulation approach to understand how channel width influences force scaling and entropic effects in polymer translocation.

Findings

Translocation time scales as the inverse of force in high-force limit.

Entropic forces are negligible in very narrow channels for single-file translocation.

Increasing channel width introduces entropic effects that alter force scaling behavior.

Abstract

Iso-flux tension propagation (IFTP) theory and Langevin dynamics (LD) simulations are employed to study the dynamics of channel-driven polymer translocation in which a polymer translocates into a narrow channel and the monomers in the channel experience a driving force $f_{\rm c}$. In the high driving force limit, regardless of the channel width, IFTP theory predicts $\tau\propto f_{\textrm{c}}^{\beta}$ for the translocation time, where $\beta=-1$ is the force scaling exponent. Moreover, LD data show that for a very narrow channel fitting only a single file of monomers, the entropic force due to the subchain inside the channel does not play a significant role in the translocation dynamics, and the force exponent $\beta= -1$ regardless of the force magnitude. As the channel width increases the number of possible spatial configurations of the subchain inside the channel becomes significant, and the resulting entropic force causes the force exponent to drop below unity.