The Nature of Attraction between Like-Charged Rods

Levin, Yan; Arenzon, Jeferson J.; Stilck, Jürgen F.

doi:10.1103/physrevlett.83.2680

Cited by 78 publications

(52 citation statements)

References 2 publications

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“…Consequently, the dependence of the effective interactions on a model parameter can systematically be studied and the trends can be compared to experiments. In this respect our model is superior to previous studies that describe the counterion screening by linear Debye-Hückel [39,42,4,43] or nonlinear Poisson-Boltzmann theory [26,4,[44][45][46][47][48][49][50][51] and even to recent approaches that include approximatively counterion correlations [52,53]. We also emphasize that one main goal of the paper is to incorporate the molecular shape and charge pattern explicitly which is modelled in many studies simply as a homogeneously charged cylinder [39,4,54,55].…”

Section: Introductionmentioning

confidence: 76%

Effective interaction between helical biomolecules

Allahyarov

Löwen

2000

Phys. Rev. E

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The effective interaction between two parallel strands of helical bio-molecules, such as deoxyribose nucleic acids (DNA), is calculated using computer simulations of the "primitive" model of electrolytes. In particular we study a simple model for B-DNA incorporating explicitly its charge pattern as a double-helix structure. The effective force and the effective torque exerted onto the molecules depend on the central distance and on the relative orientation. The contributions of nonlinear screening by monovalent counterions to these forces and torques are analyzed and calculated for different salt concentrations. As a result, we find that the sign of the force depends sensitively on the relative orientation. For intermolecular distances smaller than 6Å it can be both attractive and repulsive. Furthermore we report a nonmonotonic behaviour of the effective force for increasing salt concentration. Both features cannot be described within linear screening theories. For large distances, on the other hand, the results agree with linear screening theories provided the charge of the bio-molecules is suitably renormalized.

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Section: Introductionmentioning

confidence: 76%

Effective interaction between helical biomolecules

Allahyarov

Löwen

2000

Phys. Rev. E

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“…Besides that, for polyelectrolytes such as DNA the interaction with the interface of charged membranes or charged particles (histones) is crucial for many biophysical properties [2]. Finally long range Coulomb interactions represent a theoretical challenge, especially for the understanding of effective attractions between like charged bodies [3,4,5,6].The adsorption of polyelectrolytes onto an oppositely charged spherical particle has recently been experimentally extensively studied [2,7,8,9]. Various authors have also investigated this phenomenon theoretically [10,11,12,13,14,15,16] and by numerical simulations [17,18,19].…”

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confidence: 99%

Conformation of a polyelectrolyte complexed to a like-charged colloid

2002

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We report results from a molecular dynamics (MD) simulation on the conformations of a long flexible polyelectrolyte complexed to a charged sphere, both negatively charged, in the presence of neutralizing counterions in the strong Coulomb coupling regime. The structure of this complex is very sensitive to the charge density of the polyelectrolyte. For a fully charged polyelectrolyte the polymer forms a dense two-dimensional "disk", whereas for a partially charged polyelectrolyte the monomers are spread over the colloidal surface. A mechanism involving the overcharging of the polyelectrolyte by counterions is proposed to explain the observed conformations.PACS numbers: 61.20. Qg, 82.70.Dd, 87.10.+e Polyelectrolytes in polar solvents are polymers carrying dissociated ionic groups. When a polyelectrolyte is in the vicinity of a charged colloidal particle, both may coagulate leading to charge complexation. Studying this process is motivated by many sources. The presence of polyelectrolytes has important effects on the stabilization of colloidal suspensions [1]. Besides that, for polyelectrolytes such as DNA the interaction with the interface of charged membranes or charged particles (histones) is crucial for many biophysical properties [2]. Finally long range Coulomb interactions represent a theoretical challenge, especially for the understanding of effective attractions between like charged bodies [3,4,5,6].The adsorption of polyelectrolytes onto an oppositely charged spherical particle has recently been experimentally extensively studied [2,7,8,9]. Various authors have also investigated this phenomenon theoretically [10,11,12,13,14,15,16] and by numerical simulations [17,18,19]. However, much less is known concerning the complexation of a charged sphere with a like-charged polyelectrolyte. To our knowledge there has been no study in this direction until now.In this Letter, we report the rather unexpected complexation between a charged sphere and a long flexible polyelectrolyte, both like (here negatively) charged. This article constitutes a first attempt to elucidate this striking phenomenon. We present results of MD simulation of the two macroions taking into account the counterions explicitly, but add for simplicity no salt. We propose a mechanism stemming from the polyelectrolyte overcharging to explain the complexation structure as well as the observed polyelectrolyte conformations.The MD method employed here is based on the Langevin equation and is the same as the one employed in previous studies [20]. Consider within the framework of the primitive model one spherical macroion characterized by a radius r 0 and a bare charge Q = −Z M e (where e is the elementary charge and Z M > 0) surrounded by an implicit solvent of relative dielectric permittivity ǫ r . The polymer chain is made up of N m monomers of diameter l. Both ends of the chain are always charged. The monomer charge fraction is f (i.e. every 1/f monomer is charged) so that the chain contains N cm = (N m − 1)f + 1 charged monomers. The monomer charg...

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“…The large gain in entropy following the dissociation of a vast number of counterions into solution stabilizes the system, because an aggregation of colloids into a small subvolume would-for reasons of global charge neutrality-also require the counterions to occupy this small volume and thereby give up much entropy. Of course, the final state of the system is always a balance between energy and entropy, and if electrostatic interactions are strong, they will ultimately overcome entropy and lead to aggregation of the colloids [19][20][21][22][23]. The resulting phenomenon of "like charge attraction" has received much attention, but it is of course only mysterious if one forgets that the entire system is neutral.…”

Section: Introductionmentioning

confidence: 99%

Screening of spherical colloids beyond mean field: A local density functional approach

et al. 2004

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We study the counterion distribution around a spherical macroion and its osmotic pressure in the framework of the recently developed Debye-Hückel-hole-cavity (DHHC) theory. This is a local density functional approach which incorporates correlations into Poisson-Boltzmann theory by adding a free energy correction based on the one-component plasma. We compare the predictions for ion distribution and osmotic pressure obtained by the full theory and by its zero temperature limit with Monte Carlo simulations. They agree excellently for weakly developed correlations and give the correct trend for stronger ones. In all investigated cases the DHHC theory and its computationally simpler zero temperature limit yield better results than the Poisson-Boltzmann theory.

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The Nature of Attraction between Like-Charged Rods

Cited by 78 publications

References 2 publications

Effective interaction between helical biomolecules

Effective interaction between helical biomolecules

Conformation of a polyelectrolyte complexed to a like-charged colloid

Screening of spherical colloids beyond mean field: A local density functional approach

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