Dynamics of polymer translocation into an anisotropic confinement

TL;DR

This study uses Langevin dynamics simulations to explore how the shape and orientation of an ellipsoidal confinement affect the translocation time of a flexible polymer through a nanopore, revealing complex dependencies on anisotropy and density.

Contribution

It introduces a detailed analysis of polymer translocation into anisotropic ellipsoidal confinements, highlighting the effects of shape asymmetry and orientation on translocation dynamics.

Findings

Anisotropic confinement slows translocation compared to isotropic spheres.

Translocation time increases with the aspect ratio of the ellipsoid.

Translocation direction (major vs. minor axis) affects the time depending on chain density.

Abstract

Using Langevin dynamics simulations, we investigate the dynamics of a flexible polymer translocation into a confined area under a driving force through a nanopore. We choose an ellipsoidal shape for the confinement and consider the dependence of the asymmetry of the ellipsoid measured by the aspect ratio on the translocation time. Compared with an isotropic confinement (sphere), an anisotropic confinement (ellipsoid) with the same volume slows down the translocation, and the translocation time increases with increasing the aspect ratio of the ellipsoid. We further find that it takes different time for polymer translocation into the same ellipsoid through major-axis and minor-axis directions, depending on the average density of the whole chain in the ellipsoid, $\phi$. For $\phi$ lower than a critical value $\phi_c$, the translocation through minor axis is faster, and vice versa. These complicated behaviors are interpreted by the degree of the confinement and anisotropic confinement induced folding of the translocated chain.