Effect of Salt Concentration on the Electrophoretic Speed of a Polyelectrolyte through a Nanopore

TL;DR

This paper extends a hydrodynamic model to analyze how salt concentration affects the electrophoretic speed of polyelectrolytes in cylindrical nanopores with surface charge, aligning theoretical predictions with experimental data.

Contribution

It introduces a model considering finite Debye layer thickness and surface charge effects, improving understanding of electrophoretic behavior in nanopores.

Findings

Transit times match recent experimental measurements.

Finite Debye layer effects significantly influence electrophoretic speed.

Surface charge on nanopore walls alters polyelectrolyte translocation dynamics.

Abstract

In a previous paper [S. Ghosal, Phys. Rev. E 74, 041901 (2006)] a hydrodynamic model for determining the electrophoretic speed of a polyelectrolyte through an axially symmetric slowly varying nanopore was presented in the limit of a vanishingly small Debye length. Here the case of a finite Debye layer thickness is considered while restricting the pore geometry to that of a cylinder of length much larger than the diameter. Further, the possibility of a uniform surface charge on the walls of the nanopore is taken into account. It is thereby shown that the calculated transit times are consistent with recent measurements in silicon nanopores.