Biochemical Techniques and Instrumentation (1+2)

3.2.4.1. Direct ELISA

In direct ELISA, a labeled primary antibody is allowed to react directly with the antigen. This is performed with antigen that is directly immobilized on the assay plate. This is not widely used, however, used in immuno histochemical staining of tissues and cells.

Double antibody sandwich (DAS) ELISA

This is the most powerful direct ELISA method. In this, the capture antibodies are coated to microtiter plate wells. The antigen is then added and allowed to bind with capture antibody. The primary antibody with enzyme conjugate is then added and it binds directly to the antigen to form the double antibody sandwich. It is called a “sandwich” ELISA because the target antigen is bound between two antibodies, the capture antibody and the detection antibody. It is more sensitive and robust.