ELISA or the enzyme-linked immunosorbent assay is a biochemical technique widely used in the research and medical field to detect the presence of specific proteins or biomolecules. In the ELISA test, two antibodies are required i.e. the primary antibody detects the presence of the specific molecule and the secondary antibody that detects the primary antibody. For visualization, the secondary antibody is conjugated with an enzyme. The enzyme may be the horseradish peroxidase or the alkaline phosphatase.