Boundary Effects on Electrophoretic Motion of Spherical Particles for Thick Double Layers and Low Zeta Potential

Ennis, Jonathan; Anderson, John L.

doi:10.1006/jcis.1996.4596

Cited by 122 publications

(183 citation statements)

References 19 publications

(48 reference statements)

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“…Its applicability and the accuracy for the electrophoresis problem of the present type were examined previously by Hsu and Kao [22] applying it to solving the electrophoresis of a sphere along the axis of a cylindrical pore, and comparing the results obtained with those of Ennis and Anderson [9] and Shugai and Carnie [10]. The former is based on a reflection method, which is unreliable if the ratio (particle radius/pore radius) is large, and the latter uses a numerical approach, which is inaccurate if this ratio is small.…”

Section: Resultsmentioning

confidence: 95%

Electrophoresis of a toroid along the axis of a cylindrical pore

Hsu

Kuo

2006

Electrophoresis

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The electrophoresis of a toroid (doughnut-shaped entity) along the axis of a long cylindrical pore is analyzed under the conditions of low surface potential and weak applied electric field. The system under consideration is capable of modeling the electrophoretic behavior of various types of biocolloid such as bacterial DNA, plasmid DNA, and anabaenopsis, in a confined space. The influences of the key parameters of the problem, including the sizes of a toroid, the radius of a pore, and the thickness of the double layer, on the electrophoretic mobility of a toroid are discussed. We show that the electrophoretic behavior of a toroid under typical conditions can be different from that of an integrated entity. For instance, although the presence of the pore wall has the effect of retarding the movement of a particle, it becomes advantageous if a toroid is sufficiently close to the boundary. Several interesting behaviors are also observed, for example, the mobility of a toroid when the boundary effect is significant can be larger than that when it is insignificant.

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Section: Resultsmentioning

confidence: 95%

Electrophoresis of a toroid along the axis of a cylindrical pore

Hsu

Kuo

2006

Electrophoresis

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“…Of course, experiments always involve finite geometries, and in some cases walls play a crucial role in electrophoresis. The linear electrophoretic motion of symmetric (spherical or cylindrical) particles near insulating or dielectric walls [5][6][7][8][9][10] and in bounded cavities or channels [11][12][13][14][15][16][17][18][19][20] has been analyzed extensively. Depending on the geometry and the double-layer thickness, walls can either reduce or enhance the translational velocity, and the rotational velocity can be opposite to the rolling typical of sedimention near a wall.…”

Section: Introductionmentioning

confidence: 99%

Induced‐charge electrophoresis near a wall

Kilic

Bazant

2011

Electrophoresis

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Induced-charge electrophoresis (ICEP) has mostly been analyzed for asymmetric particles in an infinite fluid, but channel walls in real systems further break symmetry and lead to dielectrophoresis (DEP) in local field gradients. Zhao and Bau (Langmuir, 23, 4053, 2007) predicted that a metal (ideally polarizable) cylinder is repelled from an insulating wall in a DC field. We revisit this problem with an AC field and show that attraction to the wall sets in at high frequency and leads to an equilibrium distance, where DEP balances ICEP, although, in three dimensions, a metal sphere is repelled from the wall at all frequencies. This conclusion, however, does not apply to asymmetric particles. Consistent with the experiments of Gangwal et al. (Phys. Rev. Lett., 100, 058302, 2008), we show that a metal/insulator Janus particle is always attracted to the wall in an AC field. The Janus particle tends to move toward its insulating end, perpendicular to the field, but ICEP torque rotates this end toward the wall. Under some conditions, the theory predicts steady translation along the wall, perpendicular to the field, at an equilibrium tilt angle around 45 degrees, consistent with the experiments, although improved models are needed for a complete understanding of this phenomenon.

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“…The electrophoretic motion of charged particles in the presence of a confined boundary has been broadly studied and numerous analytical expressions and simulations have been derived in a wide range of double layer thickness [37][38][39][40][41]. Among these vast studies, Ennis, Keh and Anderson have contributed massive fundamental works on mathematic modeling, provided various clues for further understanding of the membrane-based electrophoresis.…”

Section: Boundary Effects Of the Membranementioning

confidence: 99%

Investigation of mass transfer in the ion‐exchange‐membrane‐partitioned free‐flow IEF system for protein separation

2009

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In this study, novel polysulfone-based cation-exchange membranes with strong mechanical strength have been developed and applied in ion-exchange-membrane-partitioned free-flow IEF (IEM-FFIEF) to replace the conventional immobiline membranes. A fundamental understanding of protein mass transfer in the IEM-FFIEF process has been revealed experimentally with the aid of membrane-based boundary effect model contributed by Ennis et al. we have proven experimentally the existence of a pH gradient across the membrane cross-section when an IEM-FFIEF system is in operation. The boundary effects on particle velocities are calculated based on the IEF assumption and various characterizations, and are compared with the experimental results. In the IEM-FFIEF experiments, a protein mixture (BSA and myoglobin (Mb)) and sulfonated polysulfone membranes with different ion-exchange capacities are applied. Experimental results show that the real velocity and real mobility (of Mb in this study) are comparable with the mathematic model developed by Ennis et al. This suggests that the equation proposed by Ennis et al., is sufficient to capture the mass transfer through membrane in the IEM-FFIEF system after considering the effects of pore size distribution and effects of disturbed electric field. The charge properties of the membrane surface play a dominant role on the separation performance of the membranes. The newly developed porous solid-phase ion-exchange membranes may potentially and effectively replace immobilines to perform the selective function for protein separation.

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Boundary Effects on Electrophoretic Motion of Spherical Particles for Thick Double Layers and Low Zeta Potential

Cited by 122 publications

References 19 publications

Electrophoresis of a toroid along the axis of a cylindrical pore

Electrophoresis of a toroid along the axis of a cylindrical pore

Induced‐charge electrophoresis near a wall

Investigation of mass transfer in the ion‐exchange‐membrane‐partitioned free‐flow IEF system for protein separation

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