Sandwich ELISA

Definition

Sandwich ELISA is an immunoassay technique used to detect and quantify specific antigens in a sample. It involves an antigen being 'sandwiched' between two layers of antibodies.

5 Must Know Facts For Your Next Test

1. Sandwich ELISA requires two different antibodies that bind to different epitopes on the same antigen.
2. The first antibody, known as the capture antibody, is immobilized on a solid surface.
3. After adding the sample, the antigen binds to the capture antibody, and a second enzyme-linked antibody (detection antibody) is added to form the sandwich complex.
4. A substrate is then added that reacts with the enzyme linked to the detection antibody, producing a measurable signal, often a color change.
5. This method is highly specific and sensitive because it uses two antibodies for detection.

Review Questions

• What are the roles of the capture and detection antibodies in Sandwich ELISA?
• Why is Sandwich ELISA considered highly specific and sensitive?
• Describe the steps involved in performing a Sandwich ELISA.

Related terms

Direct ELISA:

An assay where an antigen is directly attached to a solid phase and detected by an enzyme-linked antibody.

Indirect ELISA:

An assay where primary antibodies bind to antigens on a solid phase, followed by enzyme-linked secondary antibodies for detection.

Monoclonal Antibody: Antibodies produced by identical immune cells that are clones of a unique parent cell, targeting one specific epitope.