Tensile elasticity of semiflexible polymers with hinge defects

Benetatos, Panayotis

doi:10.1103/physreve.96.042502

Cited by 5 publications

(7 citation statements)

References 31 publications

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“…(28)] also approaches the stretching behavior of clamped polymers for increasing stiffness and forces |F |L 2 /κ 1, irrespective of the boundary conditions, as has been predicted by Ref. [48]. Yet, stronger forces are required than for cantilevered polymers.…”

Section: Semiflexible Polymer Under Tensionsupporting

confidence: 56%

Elastic behavior of a semiflexible polymer in 3D subject to compression and stretching forces

Kurzthaler

2018

Soft Matter

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We elucidate the elastic behavior of a wormlike chain in 3D under compression and provide exact solutions for the experimentally accessible force-extension relation in terms of generalized spheroidal wave functions. In striking contrast to the classical Euler buckling instability, the force-extension relation of a clamped semiflexible polymer exhibits a smooth crossover from an almost stretched to a buckled configuration. In particular, the associated susceptibility, which measures the strength of the response of the polymer to the applied force, displays a prominent peak in the vicinity of the critical Euler buckling force. For increasing persistence length, the force-extension relation and the susceptibility of semiflexible polymers approach the behavior of a classical rod, whereas thermal fluctuations permit more flexible polymers to resist the applied force. Furthermore, we find that semiflexible polymers confined to 2D can oppose the applied force more strongly than in 3D.

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Section: Semiflexible Polymer Under Tensionsupporting

confidence: 56%

Elastic behavior of a semiflexible polymer in 3D subject to compression and stretching forces

Kurzthaler

2018

Soft Matter

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“…It is known that κ/f is the length of propagation of boundary effects along the polymer contour [21,22]. If it is much less than the total contour length L, the stretched WLC behaves independently of the boundary conditions [19,20] and therefore it is in the thermodynamic limit. This can be seen in Eq.…”

Section: Tethered Wormlike Chainmentioning

confidence: 99%

“…We should point out that semiflexible polymers are inherently finite-size systems and different boundary conditions (e.g., free hinged-hinged, transverse-position-constrained hinged-hinged, clampedclamped, etc.) yield different force-extension relations even within the Gibbs ensemble [19,20]. For example, when we constrain the end-points of a wormlike chain with hinged-hinged boundary conditions to fluctuate on a straight line defined by the tension force, the average extension for a given force is greater than that in the case of free hinged-hinged boundary conditions [20].…”

Section: Introductionmentioning

confidence: 99%

“…yield different force-extension relations even within the Gibbs ensemble [19,20]. For example, when we constrain the end-points of a wormlike chain with hinged-hinged boundary conditions to fluctuate on a straight line defined by the tension force, the average extension for a given force is greater than that in the case of free hinged-hinged boundary conditions [20]. The existence of a tension-dependent correlation length (inversely proportional to the square root of the tension) [21,22] allows approach to a thermodynamic limit as it becomes much smaller than the total contour length at the strong-tension limit, and convergence of all forceextension relations to a single curve [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Inequivalence of fixed-force and fixed-extension statistical ensembles for a flexible polymer tethered to a planar substrate

Dutta

Benetatos

2018

Soft Matter

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Recent advances in single macromolecule experiments have sparked interest in the ensemble dependence of force-extension relations. The thermodynamic limit may not be attainable for such systems, which leads to inequivalence of the fixed-force and the fixed-extension ensembles. We consider an ideal Gaussian chain described by the Edwards Hamiltonian with one end tethered to a rigid planar substrate. We analytically calculate the force-extension relation in the two ensembles and we show their inequivalence, which is caused by the confinement of the polymer to half space. The inequivalence is quite remarkable for strong compressional forces. We also perform Monte-Carlo simulations of a tethered wormlike chain with contour length 20 times its persistence length, which corresponds to experiments measuring the conformations of DNA tethered to a wall. The simulations confirm the ensemble inequivalence and qualitatively agree with the analytical predictions of the Gaussian model. Our analysis shows that confinement due to tethering causes ensemble inequivalence, irrespective of the polymer model.

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“…Let us now consider a nunchuck with semiflexible arms. In Reference [ 36 ], the force-extension relation of a semiflexible nunchuck with a hinge modeled as an orientational harmonic spring is calculated analytically, in the weakly bending approximation. (We point out that the weakly bending approximation may hold because of a strong tensile force or because of a large bending stiffness.)…”

Section: Bimodality In the Tensile Elasticity Of A Semiflexible Nunchuckmentioning

confidence: 99%

Orientational Fluctuations and Bimodality in Semiflexible Nunchucks

Benetatos

Razbin

2021

Polymers

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Semiflexible nunchucks are block copolymers consisting of two long blocks with high bending rigidity jointed by a short block of lower bending stiffness. Recently, the DNA nanotube nunchuck was introduced as a simple nanoinstrument that mechanically magnifies the bending angle of short double-stranded (ds) DNA and allows its measurement in a straightforward way [Fygenson et al., Nano Lett. 2020, 20, 2, 1388–1395]. It comprises two long DNA nanotubes linked by a dsDNA segment, which acts as a hinge. The semiflexible nunchuck geometry also appears in dsDNA with a hinge defect (e.g., a quenched denaturation bubble or a nick), and in end-linked stiff filaments. In this article, we theoretically investigate various aspects of the conformations and the tensile elasticity of semiflexible nunchucks. We analytically calculate the distribution of bending fluctuations of a wormlike chain (WLC) consisting of three blocks with different bending stiffness. For a system of two weakly bending WLCs end-jointed by a rigid kink, with one end grafted, we calculate the distribution of positional fluctuations of the free end. For a system of two weakly bending WLCs end-jointed by a hinge modeled as harmonic bending spring, with one end grafted, we calculate the positional fluctuations of the free end. We show that, under certain conditions, there is a pronounced bimodality in the transverse fluctuations of the free end. For a semiflexible nunchuck under tension, under certain conditions, there is bimodality in the extension as a function of the hinge position. We also show how steric repulsion affects the bending fluctuations of a rigid-rod nunchuck.

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Tensile elasticity of semiflexible polymers with hinge defects

Cited by 5 publications

References 31 publications

Elastic behavior of a semiflexible polymer in 3D subject to compression and stretching forces

Elastic behavior of a semiflexible polymer in 3D subject to compression and stretching forces

Inequivalence of fixed-force and fixed-extension statistical ensembles for a flexible polymer tethered to a planar substrate

Orientational Fluctuations and Bimodality in Semiflexible Nunchucks

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