Dialysis

Dialysis

1. Dialysis Submitted by : D.Sairam Course Instructor : Dr. Subhabrata Kar Course : Bioanalytical and Instrumentation-I Course Code: BSBT 202 Presentation Code: U2P2

2. Overview Introduction Principle of Dialysis MWCO Preparation of Dialysis membranes Characteristics of Regenerated Cellulose Membrane Applications of Dialysis References

3. Introduction Dialysis comes from two Greek words namely ‘ Dia ” and “Lysis” meaning splitting or separating materials through a membrane Earliest Dialysis was carried out of Crystalloids using Albumin coated parchments. Today Dialysis ( reference to medical dialysis) has become a life saving technique that is widely used all over the world. Source: Wikimedia

4.   D ialysis  is the process of separating molecules in  solution by the difference in their rates of  diffusion through a semipermeable membrane.  In dialysis, a sample and a buffer solution (called the dialysate) are separated by a semi-permeable membrane that causes different diffusion rates, thereby permitting the separation of molecules in both the sample and dialysate . It is d ue to the pore size of the membrane that large molecules in the sample cannot pass through the membrane, thereby restricting their diffusion from the sample chamber.  Once equilibrium is reached, the final concentration of molecules is dependent on the volumes of the solutions involved, and if the equilibrated dialysate is replaced (or exchanged) with fresh dialysate (see procedure below), diffusion will further reduce the concentration of the small molecules in the sample . If the equilibrated dialysate is replaced (or exchanged) with fresh dialysate (see procedure below), diffusion will further reduce the concentration of the small molecules in the sample. Principle of Dialysis

5. The M olecular-Weight cut-off (MWCO ) parameters   characterize Dialysis membranes. M embranes with MWCOs ranging from1-100,000 kDa are commercially available, membranes with MWCOs near 10 kDa are most commonly used. MWCO refers to the smallest average molecular mass of a standard molecule that will not effectively diffuse across the membrane during extended dialysis. Molecules near the MMCO value will diffuse very slowly so this shows the importance of choosing an appropriate membrane. Ideally a molecule must be at least 20- to 50-times smaller than the MWCO rating of a membrane to allow smooth diffusion. Dialysis membranes for laboratory use are typically made of a film of regenerated cellulose or cellulose esters MWCO

6. Source:http ://www.sartorius.com/en/product/product-detail/18406-25-n/

7. Preparation of Dialysis Membrane Membranes ( used in Laboratory Dialysis) are generally are made up of r egenerated Cellulose. Glycerol is frequently added as a humectant to prevent cracking during drying and to help maintain desired pore structure Pores range from 15-50 Angstroms for 3.5K, 7K and 10K MWCO membranes Regenerated cellulose is hydrophilic and easily saturated in buffer to provide a homogeneous medium for dialysis in aqueous solutes Membrane contaminants include sulfur compounds (0.01-0.3%), heavy metals (trace) and glycerol (0-21%). Most of these small compounds diffuse out of the membrane during the dialysis process> Solution: pre-dialysis

8. Characteristics of Regenerated Cellulose membrane It is an economical material that is best suited for applications where particles ( significantly large) are separated on the basis of their size. It is chemically stable in most conditions. It can be used with dilute strong acids and bases, concentrated weak acids and bases. It can tolerate pH 2 - 12 and temperatures 4 - 121  °C.  However, Biotech Grade Dialysis Membranes are preferred for processes that involve higher membrane purity and better selectivity  

9. Applications of Dialysis The applications of Dialysis are far and varied. The following is a compilation of a few of them: Haemodialysis: Removal of salts, creatinine from blood in case of Renal failure. Micro dialysis: Removal of extracellular fluid, hormones for analysis and to determine their concentrations in the body. Electrodialysis  (ED ): 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. Peritoneal  Dialysis  (PD ): It uses the patient's  peritoneum (in the  abdomen ) as a membrane across which fluids and dissolved substances (urea ,  glucose ,   albumin and molecules) are exchanged from the  blood .

10. Peritoneal Dialysis Electro Dialysis Source: National Kidney Foundation, USA

11. Reference https:// www.kidney.org/atoz/content/dialysisinfo http ://renux.dmed.ed.ac.uk/EdREN/Unitbits/historyweb/HDWorld.html http:// www.spectrumlabs.com/dialysis/biotech.html http:// www.doctorslounge.com/nephrology/articles/dialysis_adequacy/adeq3.htm http:// en.wikibooks.org/wiki/Structural_Biochemistry/Proteins/Purification/Dialysis http:// www.davita.com/kidney-disease/dialysis/motivational/the-history-of-dialysis/e/197