Centrifugation and Dialysis Techniques PDF

Significance The centrifugation is a modern and easy technique of separation Due to centrifugation, it is easy to separate cellular and sub cellular components It is used to study the effects of centrifugal forces on cells Application of centrifugation üTo separate two miscible substances ü...

Significance The centrifugation is a modern and easy technique of separation Due to centrifugation, it is easy to separate cellular and sub cellular components It is used to study the effects of centrifugal forces on cells Application of centrifugation üTo separate two miscible substances üTo analyse the hydrodynamic properties of macromolecules üPurification of mammalian cells üFractionation of subcellular organelles (including membranes/membrane fractions), fractionation of membrane vesicles üSeparating chalk powder from water üRemoving fat from milk to produce skimmed milk Application of centrifugation üSeparating particles from an air-flow using cyclonic separation üThe clarification and stabilization of wine üSeparation of urine components and blood components in forensic and research laboratories üAids in the separation of proteins using purification techniques such as salting out, eg. Ammonium sulfate precipitation 19. Dialysis  Dialysis is an operation to separate dissolved molecules based on molecular weight Dialysis bag In practice, a biological sample is placed inside a tube of semi Concentrated permeable membrane, and inside a solution much bigger container Only small molecules diffuse through buffer the collodion membrane At equilibrium, the concentration of the small molecules is the same inside and outside the membrane Macromolecules remains in the bag  Advantages 1. Dialysis is still in use today for it is very simple and is still the only way to deal with large-volume samples 2. Characterization of a candidate drug in serum binding assays or detailed study of antigen-antibody interactions 3. Proves to be the most accurate method available 4. Inexpensive and easy to perform Disadvantages 1. Slow process: it takes several hours for completion, and thus, has been replaced by gel filtration for most application  Application 1. Haemodialysis: removal of salts, creatinine from blood in case of renal failure 2. Micro dialysis: removal of extracellular fluid, hormones for analysis and to determine their concentration in the body 3. Electrodialysis: it is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference 4. Peritoneal dialysis: it uses the patient’s peritoneum (in the abdomen) as a membrane across which fluids and dissolved substances (urea, glucose, albumin and molecules) are exchanges from the blood.