Shanghai Xinfan tells you the ELISA technology double antibody sandwich method - Database & Sql Blog Articles

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ELISA is a powerful technique that relies on the specific interaction between antigens and antibodies, making it highly accurate. Additionally, because the enzyme-labeled antigen or antibody can amplify the signal by catalyzing the substrate, the method achieves high sensitivity. This combination of specificity and sensitivity makes ELISA a widely used tool in both research and clinical settings.

ELISA can be used to detect both antigens and antibodies, depending on the experimental design. The three essential components of an ELISA assay are:

(1) A solid-phase antibody or antigen, also known as the "immunosorbent." (2) An enzyme-conjugated antibody or antigen, referred to as the "conjugate." (3) A substrate that reacts with the enzyme to produce a measurable signal.

The choice of reagents, sample type, and testing conditions determines the type of ELISA used. Some common types include:

Double Antibody Sandwich Assay

This method is a non-competitive binding assay and is the most frequently used for antigen detection. It works best for antigens that have at least two distinct antigenic sites. It is not suitable for small molecule haptens that lack multiple epitopes.

The basic principle involves using two antibodies: one immobilized on a solid surface and another labeled with an enzyme. These two antibodies bind to different epitopes on the target antigen, forming a sandwich complex. The amount of enzyme-bound complex formed is directly proportional to the antigen concentration in the sample, within the detection range of the method.

The optical density (OD) of the colored product generated by the enzyme reaction is measured, allowing for the quantification of the antigen present.

If the two antibodies on the solid phase recognize different epitopes on the same antigen, this is called a "two-site sandwich" approach. Alternatively, if the solid-phase antigen and the enzyme-labeled antigen both bind to the same antibody in the sample, it's referred to as a "double antigen sandwich" method.