Enzyme-Linked Immunosorbent Assay
ELISAAlso known as: enzyme immunoassay
A plate-based assay that detects and quantifies proteins, peptides, or small molecules using antibody-enzyme conjugates and colorimetric readouts.
Enzyme-Linked Immunosorbent Assay (ELISA) is a quantitative immunoassay that uses antibody-antigen interactions and enzymatic signal amplification to measure protein concentrations in solution 1.
How It Works
In the most common sandwich ELISA format, a capture antibody is immobilized on a microplate surface. The sample is added and target analyte binds the capture antibody. A detection antibody, conjugated to an enzyme such as horseradish peroxidase (HRP), then binds a different epitope on the captured analyte. Addition of a chromogenic substrate produces a color change proportional to analyte concentration, measured by a spectrophotometric plate reader.
Other ELISA formats include direct ELISA (antigen coated directly), indirect ELISA (unlabeled primary with enzyme-conjugated secondary antibody), and competitive ELISA (analyte competes with labeled antigen for binding). Each format offers trade-offs in sensitivity, specificity, and dynamic range.
In synthetic biology, ELISA quantifies secreted proteins, measures cytokine production from engineered cell therapies, and validates biosensor outputs. Its 96- or 384-well format supports moderate-throughput screening campaigns.
Computational Considerations
Standard curve fitting using four-parameter logistic (4PL) regression models is the standard computational approach for ELISA data analysis 2. Automated plate reader software calculates unknown concentrations by interpolation, flags outliers, and assesses curve quality metrics including R-squared values and coefficient of variation across replicates. Batch correction algorithms enable comparison across plates run on different days.
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Curve-fitting algorithms generate standard curves from serial dilutions, enabling automated concentration determination and quality control across high-throughput microplate experiments.