Sandwich ELISA Schematic Procedure:
(1) Plate is coated with a capture antibody; (2) sample is added, and any antigen present binds to capture antibody; (3) detecting antibody is added, and binds to antigen; (4) enzyme-linked secondary antibody is added, and binds to detecting antibody; (5) substrate is added, and is converted by enzyme to detectable form.
Sandwich ELISA advantages:
High specificity, since two antibodies are used the antigen/analyte is specifically captured and detected
Suitable for complex samples, since the antigen does not require purification prior to measurement
Flexibility and sensitivity, since both direct and indirect detection methods can be used