Heteropolymer translocation through nanopores

TL;DR

This study explores how heteropolymer sequences influence translocation dynamics through nanopores, revealing sequence-specific effects on residence times and universal scaling laws, with implications for nanopore sequencing technology.

Contribution

It uncovers sequence-dependent translocation behaviors and interference-like patterns in residence times, advancing understanding of heteropolymer translocation mechanisms.

Findings

Average translocation time scales with chain length independently of heterogeneity.

Residence time varies strongly with sequence for short repeat units.

Pattern of residence times resembles optical interference patterns.

Abstract

We investigate the translocation dynamics of heteropolymers driven through a nanopore using a constant temperature Langevin thermostat. Specifically, we consider heteropolymers consisting of two types of monomers labeled A and B, which are distinguished by the magnitude of the driving force that they experience inside the pore. From a series of studies on polymers with sequences AnBn+m we identify both universal as well as sequence specific properties of the translocating chains. We find that the scaling of the average translocation time as a function of the chain length N remains unaffected by the heterogeneity, while the residence time of each bead is a strong function of the sequence for short repeat units. We further discover that for a symmetric heteropolymer AnBn of fixed length, the pattern exhibited by the residence time of the individual monomer has striking similarity with an interference pattern for an optical grating with N/(2n) slits. These results are relevant for designing nanopore based sequencing techniques.