Identify the chemicals represented by this artist’s conception of an antibody sandwich ELISA.

Verified step by step guidance

1. Understand the principle of a sandwich ELISA: it uses two antibodies to detect a specific antigen. The first antibody (capture antibody) is attached to the surface, and the second antibody (detection antibody) binds to the antigen, forming a 'sandwich'.
2. Identify the chemicals involved in the sandwich ELISA: the capture antibody, the antigen (target molecule), and the detection antibody, which is often linked to an enzyme for signal generation.
3. Recognize that the detection antibody is conjugated to an enzyme such as horseradish peroxidase (HRP) or alkaline phosphatase (AP), which reacts with a substrate to produce a measurable signal.
4. Note that the substrate chemical is added after the sandwich complex forms; it reacts with the enzyme to produce a color change or fluorescence, indicating the presence of the antigen.
5. Summarize the chemicals: capture antibody (immobilized), antigen (sample), detection antibody (enzyme-linked), and substrate (color/fluorescent reagent). Each plays a specific role in the detection process.

Key Concepts

Antibody Sandwich ELISA Technique

The sandwich ELISA is an immunoassay used to detect and quantify specific antigens in a sample. It involves capturing the antigen between two antibodies: a capture antibody bound to a solid surface and a detection antibody that binds to a different epitope on the antigen, forming a 'sandwich'. This method provides high specificity and sensitivity.

Role of Antibodies in ELISA

Antibodies are proteins that specifically bind to antigens. In sandwich ELISA, the capture antibody immobilizes the target antigen on the plate, while the detection antibody, often linked to an enzyme, binds the antigen to enable signal generation. Understanding antibody-antigen specificity is crucial for interpreting ELISA results.

Enzyme-Linked Detection and Signal Generation

The detection antibody in sandwich ELISA is conjugated to an enzyme that catalyzes a colorimetric or fluorescent reaction upon addition of a substrate. This enzymatic reaction produces a measurable signal proportional to the antigen concentration, allowing quantification of the target molecule in the sample.