Red blood cells (RBC) have a negative charge on their surface due to SIALIC ACID. This charge prevents the clumping of Red blood cells.
Zeta Potential principle
RBCs have a negative charge on their surface due to sialic acid. Therefore red blood cells repel the adjacent red blood cells (Having the same charge), result in the prevention of RBC clumping and sufficient oxygenation of the body.
When these cells are placed in the electrolyte solution, it attracts the negatively charged particles and repels positive charge particles, thus a double ionic cloud moves along with each cell.
This determined the effective charge in the red blood cells. It is known as the zeta potential of red blood cells.
Factors affecting zeta potential of RBC
There are three factors, which affect the zeta potential of red blood cells.
- PH of solution
- Ionic strength
How to reduce Zeta Potential in the Red Blood Cells
- LISS (Low ionic strength solution)
- Proteolytic Enzyme
- PEG (Polyethylene Glycol)
Zeta potential of proteins (Albumin)
Albumin is important for reducing the zeta potential. It is prepared from a bovine source and now commercially available as a 22% solution.
LISS (Low ionic strength solution)
It is mostly used saline in the blood bank as enhancing medium. It reduces the incubation time by up to 10 minutes. It detects most of the antibodies in the blood.
The mode of action of the proteolytic enzyme is different from all above. Proteolytic enzymes (Papain, ficin, bromelain) break the red blood membrane thus facilitate the interaction of antigen-antibody reaction.
Enzyme enhanced the antigens red blood cells includes Kell, Kidd, Lewis, Rh blood groups. But” Duffy”, “M”. “N”, “S” and “s” destroyed by these enzymes.
PEG (Polyethylene Glycol)
Polyethylene Glycol causes dehydration of cells and potentiates agglutination. Thus it enhances the second stage of agglutination.
Zeta potential significance and use
Zeta potential has importance because of the zeta potential (Negative charge) on Red blood cells, One RBC will repel other RBC due to the same charge thus it prevents agglutination of RBC and increases the oxygen-carrying capacity of Red Blood Cells.