On the importance of hydrodynamic interactions in polyelectrolyte electrophoresis

Grass, Kai; Holm, Christian

doi:10.1088/0953-8984/20/49/494217

Cited by 9 publications

(20 citation statements)

References 34 publications

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“…This leads to a qualitatively completely different behavior, showing a monotonically decreasing mobility. Agreement to the experimentally observed behaviour is only achieved as long as hydrodynamic interactions are included correctly as has been shown in detail in our previous investigations [10,11].…”

Section: Introductionsupporting

confidence: 69%

“…This approach only offers local particle-fluid interactions, and therefore destroys long-range hydrodynamic interactions. Nevertheless one can use it to compute the effective charge as has been presented in [10,11]. This effective charge is used to obtain the effect friction in the presence of hydrodynamic interactions and illustrates their importance for the electrophoretic mobility.…”

Section: Modelmentioning

confidence: 99%

“…In our case it is obviously a dynamic definition. In [10,11], we introduced several static and dynamic estimators for the effective charge and showed their equivalence at vanishing salt concentration. Here, three of them will be reviewed and applied to the case of added salt.…”

Section: Effective Chargementioning

confidence: 99%

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Mesoscale modelling of polyelectrolyteelectrophoresis

Grass

Holm

2010

Faraday Discuss.

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The electrophoretic behaviour of flexible polyelectrolyte chains ranging from single monomers up to long fragments of hundred repeat units is studied by a mesoscopic simulation approach. Abstracting from the atomistic details of the polyelectrolyte and the fluid, a coarse-grained molecular dynamics model connected to a mesoscopic fluid described by the Lattice Boltzmann approach is used to investigate free-solution electrophoresis. Our study demonstrates the importance of hydrodynamic interactions for the electrophoretic motion of polyelectrolytes and quantifies the influence of surrounding ions. The length-dependence of the electrophoretic mobility can be understood by evaluating the scaling behavior of the effective charge and the effective friction. The perfect agreement of our results with experimental measurements shows that all chemical details and fluid structure can be safely neglected, and a suitable coarse-grained approach can yield an accurate description of the physics of the problem, provided that electrostatic and hydrodynamic interactions between all entities in the system, i.e., the polyelectrolyte, dissociated counterions, additional salt and the solvent, are properly accounted for. Our model is able to bridge the single molecule regime of a few nm up to macromolecules with contour lengths of more than 100 nm, a length scale that is currently not accessible to atomistic simulations.

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Section: Introductionsupporting

confidence: 69%

Section: Modelmentioning

confidence: 99%

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Mesoscale modelling of polyelectrolyteelectrophoresis

Grass

Holm

2010

Faraday Discuss.

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“…However, by including HI, simulations accurately reproduce the experimentally observed non-monotonic behaviour of the mobility. By determining the effective charge, estimates of the effective friction were determined, and a transition from logarithmic to linear scaling with length was observed [144]. The microscopic interpretation of this phenomenon is still being discussed, but all of these studies [142][143][144] emphasized the importance of the interplay between HI and counterion condensation.…”

Section: Free-flow Electrophoresismentioning

confidence: 99%

“…By determining the effective charge, estimates of the effective friction were determined, and a transition from logarithmic to linear scaling with length was observed [144]. The microscopic interpretation of this phenomenon is still being discussed, but all of these studies [142][143][144] emphasized the importance of the interplay between HI and counterion condensation. This change is attributed to the correlated movement of the counterions in the vicinity of the polyelectrolyte, effectively cancelling long-range HI this signals the transition to a free draining regime.…”

Section: Free-flow Electrophoresismentioning

confidence: 99%

Modeling the separation of macromolecules: A review of current computer simulation methods

et al. 2009

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Theory and numerical simulations play a major role in the development of improved and novel separation methods. In some cases, computer simulations predict counterintuitive effects that must be taken into account in order to properly optimize a device. In other cases, simulations allow the scientist to focus on a subset of important system parameters. Occasionally, simulations even generate entirely new separation ideas! In this article, we review the main simulation methods that are currently being used to model separation techniques of interest to the readers of Electrophoresis. In the first part of the article, we provide a brief description of the numerical models themselves, starting with molecular methods and then moving towards more efficient coarse-grained approaches. In the second part, we briefly examine nine separation problems and some of the methods used to model them. We conclude with a short discussion of some notoriously hard-to-model separation problems and a description of some of the available simulation software packages.

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Effects of Polymer Length and Salt Concentration on the Transport of ssDNA in Nanofluidic Channels

Qian

Doi

2017

Biophysical Journal

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Electrokinetic phenomena in micro/nanofluidic channels have attracted considerable attention because precise control of molecular transport in liquids is required to optically and electrically capture the behavior of single molecules. However, the detailed mechanisms of polymer transport influenced by electroosmotic flows and electric fields in micro/nanofluidic channels have not yet been elucidated. In this study, a Langevin dynamics simulation was used to investigate the electrokinetic transport of single-stranded DNA (ssDNA) in a cylindrical nanochannel, employing a coarse-grained bead-spring model that quantitatively reproduced the radius of gyration, diffusion coefficient, and electrophoretic mobility of the polymer. Using this practical scale model, transport regimes of ssDNA with respect to the ζ-potential of the channel wall, the ion concentration, and the polymer length were successfully characterized. It was found that the relationship between the radius of gyration of ssDNA and the channel radius is critical to the formation of deformation regimes in a narrow channel. We conclude that a combination of electroosmotic flow velocity gradients and electric fields due to electrically polarized channel surfaces affects the alignment of molecular conformations, such that the ssDNA is stretched/compressed at negative/positive ζ-potentials in comparatively low-concentration solutions. Furthermore, this work suggests the possibility of controlling the center-of-mass position by tuning the salt concentration. These results should be applicable to the design of molecular manipulation techniques based on liquid flows in micro/nanofluidic devices.

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On the importance of hydrodynamic interactions in polyelectrolyte electrophoresis

Cited by 9 publications

References 34 publications

Mesoscale modelling of polyelectrolyteelectrophoresis

Mesoscale modelling of polyelectrolyteelectrophoresis

Modeling the separation of macromolecules: A review of current computer simulation methods

Effects of Polymer Length and Salt Concentration on the Transport of ssDNA in Nanofluidic Channels

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