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Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness

Quite often polymers exhibit different elastic behavior depending on the statistical ensemble (Gibbs vs. Helmholtz). This is an effect of strong fluctuations. In particular, two-state polymers, which locally or globally fluctuate between two classes of microstates, can exhibit strong ensemble inequi...

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Autores principales: Razbin, Mohammadhosein, Benetatos, Panayotis
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220998/
https://www.ncbi.nlm.nih.gov/pubmed/37242882
http://dx.doi.org/10.3390/polym15102307
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author Razbin, Mohammadhosein
Benetatos, Panayotis
author_facet Razbin, Mohammadhosein
Benetatos, Panayotis
author_sort Razbin, Mohammadhosein
collection PubMed
description Quite often polymers exhibit different elastic behavior depending on the statistical ensemble (Gibbs vs. Helmholtz). This is an effect of strong fluctuations. In particular, two-state polymers, which locally or globally fluctuate between two classes of microstates, can exhibit strong ensemble inequivalence with negative elastic moduli (extensibility or compressibility) in the Helmholtz ensemble. Two-state polymers consisting of flexible beads and springs have been studied extensively. Recently, similar behavior was predicted in a strongly stretched wormlike chain consisting of a sequence of reversible blocks, fluctuating between two values of the bending stiffness (the so called reversible wormlike chain, rWLC). In this article, we theoretically analyse the elasticity of a grafted rod-like semiflexible filament which fluctuates between two states of bending stiffness. We consider the response to a point force at the fluctuating tip in both the Gibbs and the Helmholtz ensemble. We also calculate the entropic force exerted by the filament on a confining wall. This is done in the Helmholtz ensemble and, under certain conditions, it yields negative compressibility. We consider a two-state homopolymer and a two-block copolymer with two-state blocks. Possible physical realizations of such a system would be grafted DNA or carbon nanorods undergoing hybridization, or grafted F-actin bundles undergoing collective reversible unbinding.
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spelling pubmed-102209982023-05-28 Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness Razbin, Mohammadhosein Benetatos, Panayotis Polymers (Basel) Article Quite often polymers exhibit different elastic behavior depending on the statistical ensemble (Gibbs vs. Helmholtz). This is an effect of strong fluctuations. In particular, two-state polymers, which locally or globally fluctuate between two classes of microstates, can exhibit strong ensemble inequivalence with negative elastic moduli (extensibility or compressibility) in the Helmholtz ensemble. Two-state polymers consisting of flexible beads and springs have been studied extensively. Recently, similar behavior was predicted in a strongly stretched wormlike chain consisting of a sequence of reversible blocks, fluctuating between two values of the bending stiffness (the so called reversible wormlike chain, rWLC). In this article, we theoretically analyse the elasticity of a grafted rod-like semiflexible filament which fluctuates between two states of bending stiffness. We consider the response to a point force at the fluctuating tip in both the Gibbs and the Helmholtz ensemble. We also calculate the entropic force exerted by the filament on a confining wall. This is done in the Helmholtz ensemble and, under certain conditions, it yields negative compressibility. We consider a two-state homopolymer and a two-block copolymer with two-state blocks. Possible physical realizations of such a system would be grafted DNA or carbon nanorods undergoing hybridization, or grafted F-actin bundles undergoing collective reversible unbinding. MDPI 2023-05-15 /pmc/articles/PMC10220998/ /pubmed/37242882 http://dx.doi.org/10.3390/polym15102307 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Razbin, Mohammadhosein
Benetatos, Panayotis
Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title_full Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title_fullStr Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title_full_unstemmed Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title_short Elasticity of a Grafted Rod-like Filament with Fluctuating Bending Stiffness
title_sort elasticity of a grafted rod-like filament with fluctuating bending stiffness
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220998/
https://www.ncbi.nlm.nih.gov/pubmed/37242882
http://dx.doi.org/10.3390/polym15102307
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