Introduction
The enzyme-linked immunosorbent assay (ELISA) is a plate-based immunological assay designed for detecting and quantifying substances such as peptides, proteins, antibodies and hormones in biological samples. There are three different types of ELISA: direct ELISA, competitive ELISA and sandwich EILSA.
Fig.1 Different types of ELISA
Among the three types, sandwich ELISA is the most widely used method for the detection of samples. Sandwich ELISA used two sets of antibodies for the product detection, the procedure is as follows:
1. The primary antibody (capture antibody) is the antibody raised against the antigen of interest, they were coated on the EILSA plate before the sample was added, any excess and unbound antibody is then washed from the plate.
2. The sample was added into the plate, any antigen found in the sample would bind to the primary antibody which already coated on the plate, again, any excess sample is washed from the plate.
3. The secondary antibody (detection antibody) was added. The secondary antibody is labeled with an enzyme and would bind to any target antigen already bound to the plate...
