Translocation frequency of double-stranded DNA through a solid-state nanopore

TL;DR

This study investigates how the translocation frequency of double-stranded DNA through solid-state nanopores depends on length, voltage, and salt type, revealing different regimes dominated by entropic barriers or drift.

Contribution

It provides a comprehensive analysis of DNA translocation frequency dependence on experimental parameters using a unifying convection-diffusion model.

Findings

Translocation frequency is length-dependent at high salt concentration (4M LiCl).

Translocation frequency becomes length-independent at lower salt (1M KCl).

A convection-diffusion model with an entropic barrier explains the observations.

Abstract

Solid-state nanopores are single molecule sensors that measure changes in ionic current as charged polymers such as DNA pass through. Here, we present comprehensive experiments on the length, voltage and salt dependence of the frequency of double-stranded DNA translocations through conical quartz nanopores with mean opening diameter 15 nm. We observe an entropic barrier limited, length dependent translocation frequency at 4M LiCl salt concentration and a drift-dominated, length independent translocation frequency at 1M KCl salt concentration. These observations are described by a unifying convection-diffusion equation which includes the contribution of an entropic barrier for polymer entry.