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Hard-wall entropic effect accelerates detachment of adsorbed polymer chains.

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Lee, Cheng-Tai 
Terentjev, Eugene M 

Abstract

Many previous studies of unbinding kinetics have focused on a two-state model, with fully bonded and free states, which may not extend to more complicated biopolymer dynamics involving other reactions. Here we address the kinetic rate of this process at the segment level, as it is influenced by a growing dangling end of the chain. We use the mean first-passage time approach and treat the polymer as a chain attached to a wall through a succession of spring potentials, with two distinct regions of bonded and free segments. The interaction between the wall and free-moving chain end adds an entropic repulsion to this process. We estimate the average monomer detachment rate K as a function of the free dangling length L. For a flexible polymer, we find an acceleration factor in the average detachment rate depending on L and the details of the spring bond; when L is long, this factor is a simple ratio of its breaking distance to the natural bond length. For a semiflexible filament, we examine the regime where L is shorter than persistence length L_{p}, as the limit opposite to that of the flexible chain. An enhancing factor also appears, speeding up the filament unbinding when the free length grows; for a long rigid rod, this factor becomes two, independently of the bond details. We also examine the total unbinding time of an irreversible detaching process by integrating (1/K) over polymer length and discover that its power-law scaling with chain length is smaller than one, over the commonly seen range of polymer size.

Description

Keywords

4902 Mathematical Physics, 40 Engineering, 49 Mathematical Sciences

Journal Title

Phys Rev E

Conference Name

Journal ISSN

2470-0045
2470-0053

Volume Title

100

Publisher

American Physical Society (APS)

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/J017639/1)
This work is funded by the Theory of Condensed Matter Critical Mass Grant from EPSRC (EP/J017639).