Birefringence due to free electrophoresis

Bertolotto, J. A.; Roston, Graciela B.; Ascheri, María Eva; Campo, M. G.

doi:10.1016/s0378-4371(03)00474-6

Cited by 9 publications

(13 citation statements)

References 7 publications

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“…For an applied electric field in the transversal direction of the macroion (Y axis) the perpendicular saturation electric field is obtained doing θ = π/2 and ψ = 0 in Eq. (8). This saturation field results πλ 0 /4K.…”

Section: Induced Dipole Moment Saturation Effectsmentioning

confidence: 91%

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

Bertolotto

Umazano

2016

AIP Advances

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In the present work we make a theoretical study of the steady state electric linear dichroism of DNA fragments in aqueous solution. The here developed theoretical approach considers a flexible bent rod model with a saturating induced dipole moment. The electric polarizability tensor of bent DNA fragments is calculated considering a phenomenological model which theoretical and experimental backgroung is presented here. The model has into account the electric polarizability longitudinal and transversal to the macroion. Molecular flexibility is described using an elastic potential. We consider DNA fragments originally bent with bending fluctuations around an average bending angle. The induced dipole moment is supposed constant once the electric field strength grows up at critical value. To calculate the reduced electric linear dichroism we determine the optical factor considering the basis of the bent DNA perpendicular to the molecular axis. The orientational distribution function has into account the anisotropic electric properties and the molecule flexibility. We applied the present theoretical background to fit electric dichroism experimental data of DNA fragments reported in the bibliography in a wide range of molecular weight and electric field. From these fits, values of DNA physical properties are estimated. We compare and discuss the results here obtained with the theoretical and experimental data presented by other authors. The original contributions of this work are: the inclusion of the transversal electric polarizability saturating with the electric field, the description of the electric properties with an electric polarizability tensor dependant on the bending angle and the use of an arc model originally bent.

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Section: Induced Dipole Moment Saturation Effectsmentioning

confidence: 91%

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

Bertolotto

Umazano

2016

AIP Advances

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“…On the other hand, in a previous work [4] we explained this phenomenon by modeling the DNA fragments as broken rod molecules (BRM) that, under the action of an applied electric field, move by electrophoresis originating a positive birefringence. This is due to the fact that the translation rotation coupling orientates the BRM with its bisector parallel to the applied electric field.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, on the basis of the theory developed in previous works [4], [5], [7], [8] we calculate the electric dichroism of DNA fragments modeled as flexible charged and polarizable BRM. The orientational distribution function of the molecules is obtained from the Fokker-Planck equation of the system by means of a perturbation method until the fourth order of field E both for the terms involving q and for the ones depending on the electric polarizability.…”

Section: Introductionmentioning

confidence: 99%

“…After some calculations we arrive to the following expression where X is the interaction energy of the incident linearly polarized light parallel to the X axis (this axis is perpendicular to the orienting electric field E) and is given by X = 2JX 2 (-cos 9 cos \jf sin (j> -cos (j> sin \jf) + sin 2 y\ 2 -J (cos 0 cos Y -cos 9 sin <j> sin \jf) (4) whereas Z is the interaction energy of the incident linearly polarized light parallel to the Z axis (this axis is parallel to the orienting electric field E) and is represented by the following formula Z = 2\i 2 sin 2 9 cos 2 \jf+sin 2 yf sin 2 X…”

Section: Introductionmentioning

confidence: 99%

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Reduced Electric Linear Dichroism of DNA Fragments in Aqueous Solutions

Bertolotto¹,

Roston²,

Corral³

et al. 2007

AIP Conference Proceedings

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Articles you may be interested in DNA translocation through short nanofluidic channels under asymmetric pulsed electric field Biomicrofluidics 8, 024114 (2014); 10.1063/1.4871595Electric and hydrodynamic stretching of DNA-polymer conjugates in free-solution electrophoresis A Brownian dynamics-finite element method for simulating DNA electrophoresis in nonhomogeneous electric fields Abstract. We calculate the reduced electric linear dichroism at the steady state for DNA fragments in aqueous solutions modeled as flexible broken rod molecules (BRM). The electrical and optical properties of the BRM are characterized by the corresponding tensors and by a charge q with a uniform linear distribution. Each rod has N monomers that are chromophore groups with an average transition probability tensor. The reduced electric linear dichroism of BRM solution is calculated from the anisotropy in the absorption of each molecule, integrating over all the orientations, employing the steady-state orientational distribution function of the system. We first obtain the analytical solution of the Fokker-Planck equation for the system by using a perturbation method where the orientational distribution function is expanded in powers of the perturbation parameter until the fourth order. Then we solve the differential equation for each order of perturbation applying the Fourier method for expanding series. Finally, we compare the results of this theory with experimental curves of reduced electric linear dichroism as a function of the electric field for aqueous solutions of DNA fragments.

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“…Nowadays, the influence of hydrodynamic coupling on the electro-optical effects (electric birefringence and dichroism) of DNA fragments has been studied through Brownian dynamic simulation [3][4][5] and theoretical methods. [6][7][8][9][10][11][12][13][14][15] Theoretical analytic results have been reported only for the limit of low electric field strength because the study of the orientational process induced by electric field has mathematical difficulties. Simulation studies early made are applied for arbitrary electric field strength but they have a disadvantage; they require computer simulations that are too extensive.…”

Section: Introductionmentioning

confidence: 99%

Electric linear dichroism transients of bent DNA fragments

Umazano

Bertolotto

2013

The Journal of Chemical Physics

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We study the effect of translational-rotational hydrodynamic coupling on the transient electric linear dichroism of DNA fragments in aqueous solution. As opposed to previous theoretical works, where analytic solutions valid in the limit of low electric field were reported, we present here a numerical approach which allows to obtain numerical results valid independently from the applied electric field strength. Numerical procedures here used are an extension to the transient-state of those developed in a previous work for the study of the problem in the steady-state. The molecular orientational processes induced by an electric field is characterized with statistical arguments solving the FokkerPlanck equation by means of the finite difference method to know the orientational distribution function of molecules.

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Birefringence due to free electrophoresis

Cited by 9 publications

References 7 publications

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

Reduced Electric Linear Dichroism of DNA Fragments in Aqueous Solutions

Electric linear dichroism transients of bent DNA fragments

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