ELECTROPHORESIS COMPLETENOTES MSC BS.pptx

Electrophoresis notes

1. LECTURE 21 6 TH SEMESTER ELECTROPHORESIS Presented by Amna Rehman Assistant Professor Govt MAO College Lahore

2. TOPICS SUPPORTING MEDIA USED IN ELECTROPHORESIS ELECTROOSMOTIC FLOW ZETA POTENTIAL

3. SUPPORTING MEDIUM

4. FILTER PAPER

5. GELS

6. STARCH

7. AGAR OR AGAROSE GEL Agarose gels are fragile They are held together by weak hydrogen bonds Pore size is large so used to separate large molecules such as nucleic acids, large proteins and protein complexes

8. POLYACRYLAMIDE GEL

9. SEPHADEX This has already been studied in gel chromatography.

10. THIN LAYERS

11. ELECTROOSMOTIC FLOW (V.IMP) DEFINITION Electroosmotic flow (or electro-osmotic flow, often abbreviated EOF; synonymous with electroosmosis or electroendosmosis) is the motion of liquid induced by an applied potential across a porous material, capillary tube, membrane, microchannel, or any other fluid conduit (a tube or channel for conveying water or any other fluid).

12. ELECTROOSMOTIC FLOW (V.IMP)

13. EXPLANATION The electroosmotic flow (EOF) is caused by applying high-voltage to an electrolyte-filled capillary. This flow occurs when the buffer running through the silica capillary has a pH greater than 3 and the SiOH groups lose a proton to become SiO -  ions. The capillary wall then has a negative charge, which develops a double layer by attracting cations towards it. Here cations get adhere to anions and this double layer becomes stationary, while the other layer of cations along with anions is free to move along the capillary tube. The applied electric field causes the free cations to move toward the cathode creating a powerful bulk flow. The rate of the electroosmotic flow is governed by the following equation μ EOF= ϵ E ζ /4 πη

14. ZETA POTENTIAL (IMP) In this equation ε is the dielectric constant of the solution, η is the viscosity of the solution, E is the field strength, and ζ is the zeta potential. It is considered as the effective charge on the particle  Because of the separation of positively charged particles negatively charged particles, which are naturally attracted to the positively charged anode, will separate out as well.  The EOF works best with a large zeta potential between the cation layers.

15. DEFINITION The potential difference existing between the surface of a solid particle immersed in a conducting liquid (e.g. water) and the bulk of the liquid. OR In other words, zeta potential is the potential difference between the dispersion medium and the stationary layer of fluid attached to the dispersed particle. Units are volts(V) or millivolts(mV). Zeta potential explain the stability of particles in a colloidal system

16. EXPLANATION Zeta potential is a measure of charges carried by particles suspended in a liquid (mostly water). Most particles suspended in water and wastewater, e.g. clays, silica, hydrated metal oxides, paper fibers, biological cells, etc., possess negative surface charges. Positive ions in the solution are attracted to the negatively charged surface where they may be strongly adsorbed. The adsorbed layer remains rigidly attached and forms what is known as the Stern layer. Outside the Stern layer is a diffuse layer In which positive ions outnumber negative ions and balance the excess in the Stern layer. The Stern layer and diffuse layer are called double layers. 

17. THANK YOU