Question

What is the principle on which ELISA is based ?

Answer 1

ELISA (Enzyme-linked immunosorbent assay) :

1. ELISA is a plate-based technique that is used for detecting and quantifying substances such as proteins, antibodies, and hormones.
2. An enzyme such as Alkaline phosphate conjugated with an antibody reacts with a colorless substrate to generate a signal in the form of a colored product such a substrate is termed chromogenic substrate.

Principle of ELISA:

1. The principle of ELISA is based on the formation of an antigen-antibody complex.
2. Antibodies in the sample are linked with an enzyme added to the well of the plate, by addition of a specific substrate to the good results in the formation of colored product.
3. In this technique, the sample is incubated in a well of the plate.
4. Antibodies present in the sample are captured by a corresponding reaction between an antibody in the sample and coated antigen on the solid surface of the plate, after washing the unbound antibodies are removed with a washing buffer.
5. When a suitable substrate is added, the enzyme reacts to give color.
6. The color produced represents the number of antibodies or antigens present in the given sample.
7. The intensity of color produced (optical density) is measured at 450 nm on a spectrophotometer.