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Encyclopedia > Electrophoresis

For specific types of electrophoresis (for example, the process of administering medicine, iontophoresis), see electrophoresis (disambiguation). Iontophoresis is a non-invasive method of propelling high concentrations of a charged substance, normally medication or bioactive-agents, transdermally by repulsive electromotive force using a small electrical charge applied to an iontophoretic chamber containing a similarly charged active agent and its vehicle. ... Electrophoresis is a method of moving charged particles through a medium by using an electric field induced by electrodes. ...


Electrophoresis is the most known electrokinetic phenomena. It was discovered by Reuss in 1809 [1]. He observed that clay particles dispersed in water migrate under influnjnxjcence of an applied electric field. There are detailed descriptions of Electrophoresis in many books on Colloid and Interface Science[2], [3], [4],[5],[6], [7]. There is an IUPAC Technical Report [8] prepared by a group of most known world experts on the electrokinetic phenomena. Electrokinetic phenomena is a family of several different effects that occur in heterogeneous fluids or in porous bodies filled with fluid. ... For other uses, see Clay (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ... Electrokinetic phenomena is a family of several different effects that occur in heterogeneous fluids or in porous bodies filled with fluid. ...

Generally, electrophoresis is the motion of dispersed particles relative to a fluid under the influence of an electric field that is space uniform. Alternatively, similar motion in a space non-uniform electric field is called dielectrophoresis.

Electrophoresis occurs because particles dispersed in a fluid almost always carry an electric surface charge. An electric field exerts electrostatic Coulomb force on the particles through these charges. Interface and Colloid Science deals with heterogeneous systems. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ... Space has been an interest for philosophers and scientists for much of human history. ... For other uses, see Uniform (disambiguation). ... Dielectrophoresis (or DEP) is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non-uniform electric field. ... Image File history File links Size of this preview: 646 × 600 pixelsFull resolution (688 × 639 pixels, file size: 13 KB, MIME type: image/gif) Illustration of electrophoresis I, the copyright holder of this work, hereby release it into the public domain. ... Image File history File links Size of this preview: 646 × 600 pixelsFull resolution (688 × 639 pixels, file size: 13 KB, MIME type: image/gif) Illustration of electrophoresis I, the copyright holder of this work, hereby release it into the public domain. ... Electric surface charge appears practically always on an object surface when it is placed into a fluid. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrical force that one stationary, electrically charged substance of small volume (ideally, a point source) exerts on another. ...


Another force is electrostatic as well. It is known from double layer theory that all surface charges in fluids are screened with a diffuse layer. This diffuse layer has the same absolute charge value, but with opposite sign from the surface charge. The electric field induces force on the diffuse layer, as well as on the surface charge. The total value of this force equals to the first mentioned force, but it is oppositely directed. However, only part of this force is applied to the particle. It is actually applied to the ions in the diffuse layer. These ions are at some distance from the particle surface. They transfer part of this electrostatic force to the particle surface through viscous stress. This part of the force that is applied to the particle body is called electrophoretic retardation force. Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... Saturnian aurora whose reddish colour is characteristic of ionized hydrogen plasma. ... Double Layer (interfacial) (DL)is a structure that appears on the surface of an object when it is placed into a liquid. ... Double Layer (interfacial) (DL)is a structure that appears on the surface of an object when it is placed into a liquid. ... Surface charge is the electric charge present on an interface, for instance on the surface of a semiconductor material. ... ... Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... Stress is a measure of force per unit area within a body. ...


There is one more electric force, which is associated with deviation of the double layer from spherical symmetry and surface conductivity due to the excees ions in the diffuse layer. This force is called the electrophoretic relaxation force Saturnian aurora whose reddish colour is characteristic of ionized hydrogen plasma. ... Surface conductivity is an additional electric conductivity of fluid in the vicinity of the charged surface. ... Double Layer (interfacial) (DL)is a structure that appears on the surface of an object when it is placed into a liquid. ...


All these forces are balanced with hydrodynamic friction, which affects all bodies moving in viscous fluids with low Reynolds number. The speed of this motion v is proportional to the electric field strength E if the field is not too strong. Using this assumption makes possible the introduction of electrophoretic mobility μe as coefficient of proprtionality between particle speed and electric field strength: Hydrodynamics is fluid dynamics applied to liquids, such as water, alcohol, oil, and blood. ... For other uses, see Friction (disambiguation). ... Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... In fluid mechanics, the Reynolds number is the ratio of inertial forces (vsρ) to viscous forces (μ/L) and consequently it quantifies the relative importance of these two types of forces for given flow conditions. ... In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. ... This article, image, template or category should belong in one or more categories. ...

mu_e = {v over E}

Multiple theories were developed during 20th century for calculating this parameter. Ref. 1 provides an overview. Here are some of the most general conclusions.

Contents

Theory

The most known and widely used theory of electrophoresis was developed by Smoluchowski in 1903 [9] Image File history File links Size of this preview: 557 × 600 pixelsFull resolution (639 × 688 pixels, file size: 16 KB, MIME type: image/gif) Illustration for electrophoresis retardation I, the copyright holder of this work, hereby release it into the public domain. ... Image File history File links Size of this preview: 557 × 600 pixelsFull resolution (639 × 688 pixels, file size: 16 KB, MIME type: image/gif) Illustration for electrophoresis retardation I, the copyright holder of this work, hereby release it into the public domain. ... Marian Smoluchowski Marian Smoluchowski (Marian Ritter von Smolan Smoluchowski, 28 May 1872 in Vorderbrühl near Vienna - 5 September 1917 in Kraków) was a Polish scientist, pioneer of statistical physics and a mountaineer. ...

mu_e = frac{varepsilonvarepsilon_0zeta}{eta},

where ε is the dielectric constant of the dispersion medium, ε0 is the permittivity of free space (C² N m-2), η is dynamic viscosity of the dispersion medium (Pa s), and ζ is zeta potential (i.e., the electrokinetic potential of the slipping plane in the double layer). The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Interface and Colloid Science deals with heterogeneous systems. ... Permittivity is an intensive physical quantity that describes how an electric field affects and is affected by a medium. ... Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... The zeta potential in physical chemistry is measured by electrophoresis. ... This article is about the structure at interfaces in liquids. ... This article is about the structure at interfaces in liquids. ... Saturnian aurora whose reddish colour is characteristic of ionized hydrogen plasma. ...


Smoluchowski theory is very powerful because it is valid for dispersed particles of any shape and any concentration. However, it has limitations, as it does not include the Debye length κ-1. However, the Debye length must be important for electrophoresis, as follows from the Figure on the right. Increasing the thickness of the DL leads to moving the point of retardation force further from the particle surface. The thicker the DL, the smaller retardation force must be. Interface and Colloid Science deals with heterogeneous systems. ... Look up shape in Wiktionary, the free dictionary. ... For other uses, see Concentration (disambiguation). ... In plasma physics, the Debye length, named after the Dutch physical chemist Peter Debye, is the scale over which mobile charge carriers (e. ...


Detailed theoretical analysis proved that Smoluchowski theory is valid only for a sufficiently thin DL, when the Debye length is much smaller than the particle radius a: In plasma physics, the Debye length, named after the Dutch physical chemist Peter Debye, is the scale over which mobile charge carriers (e. ...

κa > > 1

This model of the "thin Double Layer" offers tremendous simplifications not only for electrophoresis theory but for many other electrokinetic theories. This model is valid for most aqueous systems because the Debye length is only a few nanometers there. It breaks only for nano-colloids in a solution with ionic strength close to water. Drinking water This article focuses on water as we experience it every day. ... A nanometre (American spelling: nanometer) is 1. ... Look up nano in Wiktionary, the free dictionary. ... A colloid or colloidal dispersion, is a form of matter intermediate between a true solution and a mixture (suspension). ... The ionic strength of a solution is a function of the concentration of all ions present in a solution. ...


Smoluchowski theory also neglects the contribution of surface conductivity. This is expressed in modern theory as conduction of small Dukhin number Surface conductivity is an additional electric conductivity of fluid in the vicinity of the charged surface. ... Dukhin number is dimensionless quantity that characterizes contribution of the surface conductivity to various electrokinetic and electroacoustic effects, as well as to conductivity and permittivity of fluid heterogeneous systems. ...

Du < < 1

The creation of an electrophoretic theory with a wider range of validity was a purpose of many studies during 20th century.


One of the most known considers an opposite asymptotic case when Debye length is larger than particle radius: In plasma physics, the Debye length, named after the Dutch physical chemist Peter Debye, is the scale over which mobile charge carriers (e. ...

κa < 1

It is a "thick Double Layer" model. A corresponding electrophoretic theory was created by Huckel in 1924 [10]. It yields the following equation for electrophoretic mobility:

mu_e = frac{2varepsilonvarepsilon_0zeta}{3eta},

This model can be useful for some nano-colloids and non-polar fluids, where the Debye length is much larger.

There are several analytical theories that incorporate surface conductivity and eliminate restriction of the small Dukhin number. Early pioneering work in that direction dates back to Overbeek [11] and Booth [12].

Modern, rigorous theories that are valid for any Zeta potential and often any κa, stem mostly from the Ukrainian (Dukhin, Shilov and others) and Australian (O'Brien, White, Hunter and others) Schools. Surface conductivity is an additional electric conductivity of fluid in the vicinity of the charged surface. ... Dukhin number is dimensionless quantity that characterizes contribution of the surface conductivity to various electrokinetic and electroacoustic effects, as well as to conductivity and permittivity of fluid heterogeneous systems. ... The zeta potential in physical chemistry is measured by electrophoresis. ...


Historically the first one was Dukhin-Semenikhin theory [13]. Similar theory was created 10 years later by O'Brien and Hunter [14]. Assuming thin Double Layer, these theories would yield results that are very close to the numerical solution provided by O'Brien and White [15].


Applications

There are many applications of electrophoresis for measurements and various operations with particulates Particulates, alternately referred to as Particulate Matter (PM) , aerosols or fine particles are tiny particles of solid or liquid suspended in the air. ...


Measurement

electrophoresis is used for studying properties of dispersed particles. In particular, for measuring zeta potential. There are several different variations of electrophoresis based techniquies. The most known are: microelectrophoresis and electrophoretic light scattering. These methods are described in details in the "Fundamentals of Interface and Colloid Science", by Lyklema [16] Interface and Colloid Science deals with heterogeneous systems. ... The zeta potential in physical chemistry is measured by electrophoresis. ... Microelectrophoresis is a method of studying electrophoresis of various dispersed particles using optical microscopy. ... Electrophoretic light scattering is based on dynamic light scattering. ...


Gel electrophoresis

Gel electrophoresis is an application of electrophoresis in molecular biology. Biological macromolecules – usually proteins, DNA, or RNA – are loaded on a gel and separated on the basis of their electrophoretic mobility. (The gel greatly retards the mobility of all molecules present.) Gel electrophoresis is a technique used for the separation of deoxyribonucleic acid, ribonucleic acid, or protein molecules through an electric charge. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Left: An RNA strand, with its nitrogenous bases. ... In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. ...


Electrophoretic displays

Electrophoretic displays (EPD's) are a class of information display that form images by electrophoretic motion of charged, colored pigment particles. Products incorporating electrophoretic displays include the Sony Librie electronic book reader, and the iRex iLiad e-newspaper tablet, both of which use electrophoretic films manufactured by E Ink Corporation. An electrophoretic display is an information display that forms visible images by rearranging charged pigment particles using an applied electric field. ... Nixie tubes, LED-display and VF-display A display device, also known as an information display is a device for visual or tactile presentation of images (including text) acquired, stored, or transmitted in various forms. ... Sony supplies the Librie EBR-1000EP, an ebook display device, to the public. ... This is about the eBook reader. ... E Ink Corporation is a privately held manufacturer of electrophoretic displays (EPDs), a kind of electronic paper. ...


Electrophoretic fingerprinting

Electrophoresis is also used in the process of DNA fingerprinting. Certain DNA segments that vary vastly among humans are cut at recognition sites by restriction enzymes (restriction endonuclease). After the resulting DNA fragments are run through electrophoresis, the distance between bands are measured and recorded as the DNA "fingerprint." A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the phosphate backbones of the double helix without damaging the bases. ...


Electrophoretic deposition

Coatings, such as paint or ceramics, can be applied by electrophoretic deposition. The technique can even be used for 3-D printing. Electrophoretic deposition (EPD), is a term for a broad range of industrial processes which includes electrocoating, electrophoretic coating, or electrophoretic painting. ...


References

Wikimedia Commons has media related to:
  1. ^ Reuss, F.F. Mem.Soc.Imperiale Naturalistes de Moscow, 2, 327 1809
  2. ^ Lyklema, J. “Fundamentals of Interface and Colloid Science”, vol.2, page.3.208, 1995
  3. ^ Hunter, R.J. "Foundations of Colloid Science", Oxford University Press, 1989
  4. ^ Dukhin, S.S. & Derjaguin, B.V. "Electrokinetic Phenomena", J.Willey and Sons, 1974
  5. ^ Russel, W.B., Saville, D.A. and Schowalter, W.R. “Colloidal Dispersions”, Cambridge University Press,1989
  6. ^ Kruyt, H.R. “Colloid Science”, Elsevier: Volume 1, Irreversible systems, (1952)
  7. ^ Dukhin, A.S. and Goetz, P.J. "Ultrasound for characterizing colloids", Elsevier, 2002
  8. ^ ”Measurement and Interpretation of Electrokinetic Phenomena”, International Union of Pure and Applied Chemistry, Technical Report, published in Pure Appl.Chem., vol 77, 10, pp.1753-1805, 2005
  9. ^ M. von Smoluchowski, Bull. Int. Acad. Sci. Cracovie, 184 (1903)
  10. ^ Huckel, E., Physik.Z., 25, 204 (1924)
  11. ^ Overbeek, J.Th.G., Koll.Bith, 287 (1943)
  12. ^ Booth, F. Nature, 161, 83 (1948)
  13. ^ Dukhin, S.S. and Semenikhin, N.M. Koll.Zhur., 32, 366 (1970)
  14. ^ O'Brien, R.W. and Hunter, R.J. Can.J.Chem., 59, 1878 (1981)
  15. ^ O'Brien, R.W. and White, L.R. J.Chem.Soc.Faraday Trans. 2, 74, 1607, (1978)
  16. ^ Lyklema, J. "Fundamentals of Interface and Colloid Science", Academic Press, vol 2, (1995)
  • http://gslc.genetics.utah.edu/units/activities/electrophoresis/
  • Voet and Voet, Biochemistry, John Whiley & sons. 1990.
  • Jahn, G. C., Hall, D.W., and Zam, S. G. 1986. A comparison of the life cycles of two Amblyospora (Microspora: Amblyosporidae) in the mosquitoes Culex salinarius and Culex tarsalis Coquillett. J. Florida Anti-Mosquito Assoc. 57, 24–27.
  • Khattak MN, Matthews RC. Genetic relatedness of Bordetella species as determined by macrorestriction digests resolved by pulsed-field gel electrophoresis. Int J Syst Bacteriol. 1993 Oct;43(4):659-64.
  • Barz, D.P.J., Ehrhard. P., Model and verification of electrokinetic flow and transport in a micro-electrophoresis device, Lab Chip, 2005, 5, 949 - 958.

ISO electrophoresis Image File history File links Commons-logo. ...


External links

See also


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Electrophoresis in which a second perpendicular electrophoretic transport is performed on the separate components resulting from the first electrophoresis.
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