Sandwich ELISA

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:

1. Coating: The wells of a 96-well microplate are pre-coated with a specific capture antibody that binds selectively to the target antigen.
2. Sample Addition: The sample containing the antigen is introduced into the wells, where the antigen binds to the immobilized capture antibody.
3. 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."
4. 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.