Assay And Assay Of Assay Essay

1444 Words Aug 15th, 2016 6 Pages
ELISA (Enzyme-Linked Immunosorbent Assay)
ELISA is a technique to detect and quantify substances like proteins, antibodies, and hormones. The target antigen is immobilized to the bottom of the well and then an antigen-specific detection antibody is added. The detection antibody makes it possible to measure results. The three most common formats of ELISA would be direct assay, indirect assay, and sandwich assay. In direct assay, the antigen immobilizes to the bottom of the well where a labeled antibody attaches to it. In indirect assay, the the antigen immobilizes to the bottom of the well and then a primary antibody binds to the antigen. After that, the labeled secondary antibody binds to the primary antibody. In sandwich assay, a pre-coated capture antibody binds to the antigen. Then, the detection primary antibody binds to the antigen and a labeled secondary antibody binds only the primary antibody. The most important step in ELISA is the detection step. There is both direct and indirect detection. In direct detection, there is only a primary antibody that is labeled, most likely with HRP (horseradish peroxidase) or AP (alkaline phosphatase). In indirect detection, a labeled secondary antibody is used that binds specifically to the primary antibody. Indirect detection is more common than direct detection because it is easy to find a variety of secondary antibodies. Also, since the primary antibody has many epitopes, there is an amplification of the signal, increasing the…

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