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Electrophorese

Non revidite
De Wikipedia, le encyclopedia libere
Pro le processo de administrar medicina, vide Iontophorese.
Pro altere usos, vide Electrophorese (disambiguation).
1. Illustration de electrophorese de un particula cargate
2. Illustration del retardation electrophoretic

Electrophorese es le motion de particulas disperse cargate o moleculas cargate dissolvite relative a un fluido sub le influentia de un campo electric spatialmente uniforme. Como regula, iste particulas e moleculas zwitterionic ha o un carga nette positive o negative, le qual es frequentemente characterisate con le potential zeta.[1][2]

Electrophorese es usate in laboratorios pro separar macromoleculas basate sur lor cargas. Le technica normalmente applica un carga negative appellate cathodo de modo que le moleculas de proteina anionic se move verso un carga positive appellate anodo.[3] Ergo, le electrophorese de particulas o moleculas cargate positivemente (cationes) es a vices appellate cataphorese, dum le electrophorese de particulas o moleculas cargate negativemente (aniones) es a vices appellate anaphorese.[4][5][6][7][8][9][10]

Electrophorese es le base pro technicas analytic usate in biochimia e biologia molecular pro separar particulas, moleculas, o iones per grandor, carga, forma, o affinitate de ligamine, sia liberemente o a transverso de un medio de supporto usante un fluxo unidirectione de carga electric.[11] Illo es usate extensivemente in le analyse de ADN, ARN e proteinas.[12]

Le "electrophorese de guttettas" liquide es significativemente differente del classic "electrophorese de particulas" a causa de characteristicas del guttetta tal como un carga superficial mobile e le non-rigiditate del interfacie. Etiam, le systema liquido–liquido, ubi il ha un interaction inter le fortias hydrodynamic e electrokinetic in ambe phases, adde al complexitate del motion electrophoretic.[13]

Historia

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Le prime observation de electrophorese occurreva durante le prime annos del 19e seculo independentemente per Gautherot in 1801 [14] e per Reuss in 1809[15]. Existe un panorama del disveloppamento ulterior del fundamentos de electrophorese e del phenomenos electrokinetic in general durante duo seculos in le libro [16].

Le historia del electrokinetica e del electrophorese pro lor applicationes le plus amplemente usate, tal como le separation molecular e le analyse chimic, comenciava con le travalio de Arne Tiselius in 1931, dum nove processos de separation e technicas de analyse de speciation chimic basate sur le electrophorese e le electrokinetica continua a esser disveloppate in le 21e seculo.[17] Tiselius, con le appoio del Fundation Rockefeller, disveloppava le electrophorese de frontiera mobile, que esseva describite in 1937 in su ben cognoscite articulo.[18]

Le methodo se extendeva lentemente usque al advento de methodos de electrophorese de zona effective in le annos 1940 e 1950, que usava papiro de filtro o geles como medios de supporto. Verso le annos 1960, methodos de electrophorese in gel de plus in plus sophisticate rendeva possibile separar moleculas biologic basate sur minute differentias physic e chimic, adjutante a stimular le ascesa del biologia molecular e del biochimia. Le electrophorese in gel e technicas connexe deveniva le base pro un ample gamma de methodos biochimic, tal como le identification de proteinas per massa peptidica, Southern blot, altere proceduras de blotting, sequentiation de DNA, e multe alteres.[19]

Theoria

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Particulas suspendite ha un carga electric superficial, fortemente afficite per species adsorbite sur le superficie,[20] sur le quales un campo electric externe exerce un fortia de Coulomb electrostatic. Secundo le theoria del duple hapa, tote le cargas superficial in fluidos es protegite per un hapa diffuse de iones, le qual ha le mesme carga absolute sed de signo opposite respective a illo del carga superficial. Le campo electric etiam exerce un fortia sur le iones in le hapa diffuse le qual ha un direction opposite a illo que age sur le carga superficial. Iste ultime fortia non es de facto applicate al particula, sed al iones in le hapa diffuse locate a alcun distantia del superficie del particula, e parte de illo es transferite usque al superficie del particula a transverso de tension viscose. Iste parte del fortia es etiam appellate fortia de retardation electrophoretic, o ERF in breve. Quando le campo electric es applicate e le particula cargate a analysar es in movimento stabile a transverso del hapa diffuse, le fortia total resultante es zero:

Considerante le resistentia sur le particulas in movimento debite al viscositate del dispersante, in le caso de un basse numero de Reynolds e un fortia de campo electric moderate E, le velocitate de deriva de un particula disperse v es simplemente proportional al campo applicate, lo que lassa le mobilitate electrophoretic μe definite como:[21]

Le theoria le plus cognoscite e amplemente usate de electrophorese esseva disvolupate in 1903 per Marian Smoluchowski:[22]

,

ubi εr es le constante dielectric del medio de dispersion, ε0 es le permissivitate del vacuo (C2 N−1 m−2), η es le viscositate dynamic del medio de dispersion (Pa s), e ζ es le potential zeta (i.e., le potential electrokinetic del plano de glissamento in le duple hapa, unitates mV o V).

Le theoria de Smoluchowski es multo potente proque illo functiona pro particulas disperse de omne forma a omne concentration. Illo ha limitationes in su validitate. Per exemplo, illo non include le longitude de Debye κ−1 (unitates m). Tamen, le longitude de Debye debe esser importante pro le electrophorese, como se seque immediatemente del Figura 2, "Illustration del retardation electrophoretic". Augmentar le spissitate del duple hapa (DL) duce a remover le puncto del fortia de retardation plus longe del superficie del particula. Quanto plus spisse es le DL, tanto minor debe esser le fortia de retardation.

Analyse theoretic detaliate provava que le theoria de Smoluchowski es valide solmente pro un DL sufficientemente fin, quando le radio del particula a es multo major que le longitude de Debye:

.

Iste modelo de "duple hapa fin" offere simplificationes tremende non solmente pro le theoria de electrophorese sed pro multe altere theorias electrokinetic. Iste modelo es valide pro le majoritate del systemas aquee, ubi le longitude de Debye es usualmente solmente alcun nanometros. Illo solmente fali pro nano-colloides in solution con fortia ionic proxime a illo del aqua.

Le theoria de Smoluchowski etiam neglige le contributiones del conductivitate superficial. Isto es exprimite in le theoria moderne como condition de parve numero de Dukhin:

In le effortio de expander le rango de validitate del theorias electrophoretic, le caso asymptotic opposite esseva considerate, quando le longitude de Debye es plus grande que le radio del particula:

.

Sub iste condition de un "duple hapa spisse", Erich Hückel[23] prediceva le sequente relation pro le mobilitate electrophoretic:

.

Iste modelo pote esser utile pro alcun nanoparticulas e fluidos non-polar, ubi le longitude de Debye es multo plus grande que in le casos usual.

Il ha plure theorias analytic que incorpora le conductivitate superficial e elimina le restriction de un parve numero de Dukhin, initiate per Theodoor Overbeek[24] e F. Booth[25]. Le theorias moderne e rigorose que es valide pro omne potential zeta e frequentemente omne aκ proveni principalmente del theoria de Dukhin–Semenikhin.[26][1]

In le limite del duple hapa fin, iste theorias confirma le solution numeric al problema fornite per Richard W. O'Brien e Lee R. White.[27]

Pro modular scenariios plus complexe, iste simplificationes deveni inaccurate, e le campo electric debe esser modulate spatialmente, traciante su magnitude e direction. Le equation de Poisson pote esser usate pro modular iste campo electric spatialmente variante. Su influentia sur le fluxo de fluido pote esser modulate con le lege de Stokes,[28] dum le transporto de differente iones pote esser modulate usante le equation de Nernst–Planck. Iste approche combinate es referite como le equationes de Poisson-Nernst-Planck-Stokes. Illo ha essite validate pro le electrophorese de particulas.[29]

Vide etiam

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Referentias

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  1. 1 2 (10 de april 2025) Zeta Potential: Fundamentals, Methods, and Applications. London Cambridge, MA: Academic Press. ISBN: 978-0443334436.
  2. ↑ Michov, B. (2022). Electrophoresis Fundamentals: Essential Theory and Practice. De Gruyter, ISBN 9783110761627. doi:10.1515/9783110761641. ISBN: 9783110761641.
  3. ↑ Kastenholz, B. (10 de april 2006). “Comparison of the electrochemical behavior of the high molecular mass cadmium proteins in Arabidopsis thaliana and in vegetable plants on using preparative native continuous polyacrylamide gel electrophoresis (PNC-PAGE)”. Electroanalysis 18 (1): 103–6. doi:10.1002/elan.200403344.
  4. ↑ Lyklema, J. (1995). Fundamentals of Interface and Colloid Science 2, 3.208.
  5. ↑ Hunter, R.J. (1989). Foundations of Colloid Science. Oxford University Press.
  6. ↑ (1974) Electrokinetic Phenomena. J. Wiley and Sons.
  7. ↑ (1989) Colloidal Dispersions. Cambridge University Press. ISBN: 9780521341882.
  8. ↑ Kruyt, H.R. (1952). Colloid Science 1, Irreversible systems. Elsevier.
  9. ↑ (2017) Characterization of liquids, nano- and micro- particulates and porous bodies using Ultrasound. Elsevier. ISBN: 978-0-444-63908-0.
  10. ↑ Anderson, J.L. (1 de januario 1989). “Colloid Transport by Interfacial Forces” (in anglese). Annual Review of Fluid Mechanics 21 (1): 61–99. doi:10.1146/annurev.fl.21.010189.000425. ISSN 0066-4189. Bibcode: 1989AnRFM..21...61A.
  11. ↑ Malhotra, P. (2023). Analytical Chemistry: Basic Techniques and Methods. Springer, ISBN 9783031267567, 346.
  12. ↑ Garfin, D.E. (10 de april 1995). “Chapter 2 – Electrophoretic Methods”. Introduction to Biophysical Methods for Protein and Nucleic Acid Research: 53–109. doi:10.1016/B978-012286230-4/50003-1.
  13. ↑ “Mechanistic studies of droplet electrophoresis: A review” (10 de april 2021). Electrophoresis 42 (7–8): 869–880. doi:10.1002/elps.202000358. PMID: 33665851.
  14. ↑ Gautherot N (1801). “Mémoire sur le Galvanisme”. Annales de Chimie ou Récueil: 203-210.
  15. ↑ Reuss FF (1809). “Sur un nouvel effet de l'électricité galvanique”. Mem Soc Imp Natur Moscou 2: 327-337.
  16. ↑ (10 de april 2025) Zeta Potential: Fundamentals, Methods, and Applications. London Cambridge, MA: Academic Press. ISBN: 978-0-443-33443-6.
  17. ↑ Malhotra, P. (2023). Analytical Chemistry: Basic Techniques and Methods. Springer, ISBN 9783031267567, 346.
  18. ↑ Tiselius, Arne (1937). “A new apparatus for electrophoretic analysis of colloidal mixtures”. Transactions of the Faraday Society 33: 524–531. doi:10.1039/TF9373300524.
  19. ↑ Michov, B. (2022). Electrophoresis Fundamentals: Essential Theory and Practice. De Gruyter, ISBN 9783110761627. doi:10.1515/9783110761641. ISBN: 9783110761641.
  20. ↑ “The effects of carboxylic acids on the aqueous dispersion and electrophoretic deposition of ZrO2” (2012). Journal of the European Ceramic Society 32 (1): 235–244. doi:10.1016/j.jeurceramsoc.2011.08.015.
  21. ↑ “Anodic aqueous electrophoretic deposition of titanium dioxide using carboxylic acids as dispersing agents” (2011). Journal of the European Ceramic Society 31 (6): 1041–1047. doi:10.1016/j.jeurceramsoc.2010.12.017.
  22. ↑ von Smoluchowski, M. (1903). “Contribution à la théorie de l'endosmose électrique et de quelques phénomènes corrélatifs”. Bull. Int. Acad. Sci. Cracovie 184.
  23. ↑ Hückel, E. (1924). “Die kataphorese der kugel”. Phys. Z. 25.
  24. ↑ Overbeek, J.Th.G (1943). “Theory of electrophoresis — The relaxation effect”. Koll. Bith..
  25. ↑ Booth, F. (1948). “Theory of Electrokinetic Effects”. Nature 161 (4081): 83–86. doi:10.1038/161083a0. PMID: 18898334. Bibcode: 1948Natur.161...83B.
  26. ↑ Dukhin, S.S. e Semenikhin N.V. "Theory of double layer polarization and its effect on electrophoresis", Koll.Zhur. USSR, volume 32, pagina 366, 1970.
  27. ↑ O'Brien, R.W. (1978). “Electrophoretic mobility of a spherical colloidal particle”. J. Chem. Soc. Faraday Trans. 2 (74). doi:10.1039/F29787401607.
  28. ↑ “Motility of Catalytic Nanoparticles through Self-Generated Forces” (4 de novembre 2005). Chemistry - A European Journal 11 (22): 6462–6470. Wiley. doi:10.1002/chem.200500167. ISSN 0947-6539. PMID: 16052651. Bibcode: 2005ChEuJ..11.6462P.
  29. ↑ “Electrokinetic locomotion due to reaction-induced charge auto-electrophoresis” (13 de junio 2011). Journal of Fluid Mechanics 680: 31–66. Cambridge University Press (CUP). doi:10.1017/jfm.2011.132. ISSN 0022-1120. Bibcode: 2011JFM...680...31M.

Lectura ulterior

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  • Barz, D.P.J. (2005). “Model and Verification of Electrokinetic Flow and Transport in a Micro-Electrophoresis Device”. Lab Chip 5 (9): 949–958. doi:10.1039/b503696h. PMID: 16100579.
  • Jahn, G.C. (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, M.N. (1993). “Genetic Relatedness of Bordetella Species as Determined by Macrorestriction Digests Resolved by Pulsed-Field Gel Electrophoresis”. Int. J. Syst. Bacteriol. 43 (4): 659–64. doi:10.1099/00207713-43-4-659. PMID: 8240949.
  • Shim, J. (2007). “Modeling and Simulation of IEF in 2-D Microgeometries”. Electrophoresis 28 (4): 527–586. doi:10.1002/elps.200600402. PMID: 17253629.
  • Voet and Voet (1990). Biochemistry. John Wiley & Sons.Patrono:Full citation needed

Ligamines externe

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