Adsorption assisted translocation of a chain molecule through a pore in a spherical vesicle

TL;DR

This paper investigates how adsorption influences the free energy landscape of polymer translocation through a vesicle pore, revealing that adsorption can facilitate translocation by removing entropic barriers and that crossing time scales linearly with polymer length.

Contribution

It introduces a detailed free energy analysis of polymer translocation driven by adsorption, highlighting the role of surface interactions and providing a scaling law for crossing time.

Findings

Adsorption on the inner surface reduces entropic barriers.

Free energy profile depends on adsorption energy and polymer segments.

Crossing time scales linearly with polymer length, N.

Abstract

We analyze the free energy for translocation of a polymer from the outside of a spherical vesicle to the inside. The process is assumed to be driven by the adsorption of the polymer on the inner surface of the vesicle. We argue that in the case where the polymer is adsorbed on the outer surface too, the entropic barrier for translocation is absent. We analyze the adsorption energy and find the free energy profile for the process. We argue that the motion corresponds to a polymer crossing a region with a change in free energy per segment. Based upon our earlier analsis of the behaviour of kinks in such a problem, we conclude that the translocation can occur with a crossing time $t_{cross}\sim N$.