Sandwich ELISA- Steps and Advantages
ELISA stands for enzyme-linked immunosorbent assay. It is a widely used technique in biomedical research and clinical diagnostics that uses antibodies and enzymes to detect and quantify specific molecules in a sample. ELISA is based on the principle of antigen-antibody binding, which is a specific and selective interaction between two molecules that have complementary shapes and charges. Antibodies are proteins produced by the immune system that can recognize and bind to foreign molecules (antigens) with high specificity and affinity. Enzymes are biological catalysts that can speed up chemical reactions and produce a measurable signal, such as a color change or a fluorescent glow.
In sandwich ELISA, two types of antibodies are used to detect the antigen of interest: capture and detection antibodies. Capture antibodies are the ones that are coated and immobilized onto the wells of microtiter plates. They bind to the antigen in the sample and capture it on the surface. Detection antibodies are the ones that are added after the sample incubation and washing steps. They bind to a different epitope of the antigen than the capture antibodies, forming a sandwich complex. Detection antibodies are usually conjugated to an enzyme that can catalyze a colorimetric or fluorescent reaction when a substrate is added.
Sandwich ELISA is a type of enzyme-linked immunosorbent assay (ELISA) that is used to detect and quantify a specific antigen in a sample. The name "sandwich" refers to the fact that the antigen is bound between two layers of antibodies: a capture antibody and a detection antibody. The capture antibody is immobilized on a solid surface, such as a microtiter plate, and binds to the antigen in the sample. The detection antibody is conjugated to an enzyme that can catalyze a colorimetric or fluorescent reaction when exposed to a substrate. The amount of signal produced by the enzyme-substrate reaction is proportional to the amount of antigen present in the sample.
Sandwich ELISA is a type of enzyme-linked immunosorbent assay that uses two specific antibodies to capture and detect an antigen in a sample. The name "sandwich" refers to the fact that the antigen is sandwiched between two antibodies: one that is immobilized on a solid surface (capture antibody) and one that is conjugated to an enzyme (detection antibody). The enzyme produces a colorimetric, fluorescent or electrochemical signal when it reacts with a substrate, which can be measured to quantify the amount of antigen present in the sample. The following are the detailed steps and method of Sandwich ELISA:
- Prepare a surface to which a known quantity of capture antibody is bound.
- Block any nonspecific binding sites on the surface.
- Add antigen-containing sample to the plate.
- Add a specific antibody as detection antibody that binds to another epitope of the antigen and is conjugated to an enzyme.
- Add substrate that is converted by the enzyme into a color or fluorescent or electrochemical signal.
Sandwich ELISA is a widely used technique for the detection and quantification of antigens in biological samples. It has several advantages over other types of ELISA, such as:
- High specificity
- Suitability for complex samples
- Good flexibility and sensitivity
Sandwich ELISA is a powerful tool for biomedical research and clinical diagnostics, as it can provide accurate and reliable measurements of antigens in various samples. It can be used for detecting biomarkers of diseases, monitoring immune responses, evaluating vaccine efficacy, screening for drug candidates, and many other applications.
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