Principle of ELISA test

Enzyme-linked immunosorbent assay (ELISA) is an enzyme-labeled solid-phase immunoassay technology. The basic principle is to bind the antigen (or antibody) to the solid-phase carrier, convert the antigen (or antibody) and a certain enzyme into an enzyme-labeled antigen (or antibody). During the detection, the sample to be tested and the enzyme-labeled antigen (or antibody) are reacted with the antigen (or antibody) on the solid-phase carrier according to a certain procedure, and then the unreacted part is removed by washing method. After the substrate is added, the substrate The enzyme bound to the solid phase carrier catalyzes the production of colored substances. By qualitatively or quantitatively detecting the amount of colored products, the content of the substance to be tested in the sample can be determined.

Plastic solid-phase carriers generally replace polystyrene, and the process of binding antigens or antibodies to solid-phase carriers is called coating. When the concentration of the coated protein is too low, the surface of the solid phase carrier cannot be completely covered, and the serum samples added later and the protein of the enzyme-bound protein will also partially adsorb to the surface of the solid phase carrier, resulting in non-specific color development. In this case, 1%-5% bovine serum albumin or 5%-20% calf serum needs to be coated again to eliminate interference. This process is called blocking.

ELISA can be used to detect antigens and antibodies. The most commonly used method for detecting antigens is the double antibody sandwich method, and the most common indirect method for detecting antibodies. Both of these methods are non-competitive binding tests. HBeAb and HBcAb.

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