Length-dependent translocation of polymers through nanochannels

TL;DR

This paper investigates how polymer chain length influences translocation through nanochannels, revealing two regimes based on the chain's length relative to a critical penetration length, with implications for biological transport.

Contribution

It introduces a combined analytical and numerical approach to identify the critical length and translocation regimes, extending previous models to shorter chains.

Findings

Long chains translocate independently of length

Short chains' translocation depends on chain length

Critical penetration length determines translocation regime

Abstract

We consider the flow-driven translocation of single polymer chains through nanochannels. Using analytical calculations based on the de Gennes blob model and mesoscopic numerical simulations, we estimate the threshold flux for the translocation of chains of different number of monomers. The translocation of the chains is controlled by the competition between entropic and hydrodynamic effects, which set a critical penetration length for the chain before it can translocate through the channel. We demonstrate that the polymers show two different translocation regimes depending on how their length under confinement compares to the critical penetration length. For polymer chains longer than the threshold, the translocation process is insensitive to the number of monomers in the chain as predicted in Sakaue {\it et al.}, {\it Euro. Phys. Lett.}, {\bf 72} 83 (2005). However, for chains shorter than the critical length we show that the translocation process is strongly dependent on the length of the chain. We discuss the possible relevance of our results to biological transport.