What is the Difference Between Sandwich Elisa and Competitive Elisa?

The main difference between sandwich ELISA and competitive ELISA lies in the way the antigen is detected and the number of antibodies used. Here are the key differences:

Sandwich ELISA:

Requires two antibodies specific for different epitopes of the antigen.
One antibody is coated on the surface of the multi-well plate and used as a capture antibody, while the other antibody is conjugated and facilitates the detection of the antigen.
Highly sensitive and robust, as the antibody binds to two sites on the antigen.
Suitable for analyzing complex samples, such as tissue culture supernatants or tissue lysates.
Has a lower risk of cross-reactivity and non-specific binding.

Competitive ELISA:

Requires only one antibody for the detection of the antigen of interest.
Used when there is only one antibody available to detect the antigen, or when the protein of interest is too small to efficiently sandwich with two antibodies.
Less sensitive than sandwich ELISA.
Commonly used for small molecules and assessing antibody affinity and specificity.
Faster, more flexible, and has good reproducibility, but may be less sensitive to experimental errors.

In summary, sandwich ELISA is more sensitive and specific, requiring two antibodies for the detection of the antigen, while competitive ELISA uses only one antibody and is suitable for small molecules or when only one antibody is available.

On this page

What is the Difference Between Sandwich Elisa and Competitive Elisa?

Comparative Table: Sandwich Elisa vs Competitive Elisa

Here is a table comparing the differences between Sandwich ELISA and Competitive ELISA:

Parameter	Sandwich ELISA	Competitive ELISA
Purpose	Detect and quantify antigens in immunoassays	Detect and quantify antibodies in immunoassays
Antibodies	Uses two antibodies specific to the same protein but at different epitopes	Uses two antigens, one immobilized and the other in the sample
Sensitivity	More sensitive and robust due to the antibody binding to two sites on the antigen	Less sensitive to experimental errors, but generally less sensitive than sandwich ELISA
Specificity	High specificity as two antibodies are used to detect the antigen	Detection signal inversely correlates with the amount of antigen in the sample
Sample Preparation	Analyte does not need to be purified prior to the assay	Requires only one antibody to detect the antigen
Application	Suitable for analyzing complex samples, such as tissue culture supernatants or tissue lysates	Useful for detecting small antigens with only a single antibody epitope
Cross-Reactivity	Risk of cross-reactivity and non-specific binding	Less risk of cross-reactivity and non-specific binding

Sandwich ELISA is commonly used to detect and quantify antigens in immunoassays, while Competitive ELISA is commonly used to detect and quantify antibodies in immunoassays.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.