Blocker effect on diffusion resistance of a membrane channel. Dependence on the blocker geometry

TL;DR

This paper develops a theoretical model to understand how the size and shape of large analyte blockers within nanopores affect the diffusion resistance for small solutes, validated by simulations.

Contribution

It introduces analytical expressions for diffusion resistance considering different blocker geometries within cylindrical nanopores, advancing nanopore sensing theory.

Findings

Good agreement between theory and Brownian dynamics simulations.

Diffusion resistance depends on blocker geometry and placement.

Analytical models cover smooth and abrupt radius changes.

Abstract

Being motivated by recent progress in nanopore sensing, we develop a theory of the effect of large analytes, or blockers, trapped within the nanopore confines, on diffusion flow of small solutes. The focus is on the nanopore diffusion resistance which is the ratio of the solute concentration difference in the reservoirs connected by the nanopore to the solute flux driven by this difference. Analytical expressions for the diffusion resistance are derived for a cylindrically symmetric blocker whose axis coincides with the axis of a cylindrical nanopore in two limiting cases where the blocker radius changes either smoothly or abruptly. Comparison of our theoretical predictions with the results obtained from Brownian dynamics simulations shows good agreement between the two.