Sandwich ELISA
Sandwich ELISA is a type of Enzyme-Linked Immunosorbent Assay used for the precise and quantitative measurement of specific antigens in complex samples. It is called "sandwich" because the target antigen is captured between two antibodies: a capture antibody and a detection antibody, providing high specificity and sensitivity.
Principle of Sandwich ELISA:
- Coating: The wells of a 96-well microplate are pre-coated with a specific capture antibody that binds selectively to the target antigen.
- Sample Addition: The sample containing the antigen is introduced into the wells, where the antigen binds to the immobilized capture antibody.
- Detection Antibody: A second, enzyme-linked detection antibody is added, binding to a different epitope on the target antigen, thus forming the antibody-antigen-antibody "sandwich."
- Enzyme Conjugation: If the detection antibody is not directly conjugated to an enzyme, a secondary enzyme-conjugated antibody may be applied.
Contents of Sandwich ELISA Kits:
- Pre-coated microplate with a capture antibody specific to the target antigen.
- Detection antibody (enzyme-conjugated or requiring a secondary antibody).
- Standard antigen for preparing a calibration curve.
- Substrate solution for colorimetric development.
- Stop solution to terminate the reaction.
- Wash buffers, sample diluents, and assay buffers.
- Detailed protocol for sample preparation and assay execution.
Applications of Sandwich ELISA:
- Biomarker research: Measuring levels of specific proteins, such as cytokines, hormones, or growth factors in clinical or research samples.
- Clinical diagnostics: Detecting antigens associated with diseases, such as infectious agents, autoantibodies, or cancer markers.
- Pharmacokinetics: Quantifying therapeutic drug levels in biological samples.
- Immunology studies: Assessing cytokines and immune-related proteins to understand immune responses and inflammatory processes.
Sandwich ELISA remains a gold-standard assay for quantitative antigen detection in research and clinical diagnostics due to its robustness, reliability, and precision.
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