AtaGenix Laboratories
AtaGenix Laboratories
Release time: 2026-03-31 View volume: 22
ELISA (enzyme-linked immunosorbent assay) is one of the most widely used immunoassay techniques in biomedical research. Four main formats exist, each suited to different experimental needs. This guide explains when to use each type and the trade-offs involved.
| Format | Principle | Pros | Cons | Best For |
|---|---|---|---|---|
| Direct | Antigen coated → enzyme-labeled primary Ab | Fastest; fewest steps; no secondary Ab cross-reactivity | Low sensitivity; each primary Ab must be labeled | Screening when speed matters |
| Indirect | Antigen coated → primary Ab → enzyme-labeled secondary Ab | Signal amplification; one secondary Ab works for many primaries | Higher background; extra incubation step | Antibody titer measurement, serum screening |
| Sandwich | Capture Ab coated → antigen → detection Ab (labeled) | Highest specificity and sensitivity; quantitative | Requires matched antibody pair; more complex development | Cytokine/biomarker quantification, diagnostics |
| Competitive | Sample antigen competes with labeled antigen for Ab binding | Works for small molecules and haptens; measures inhibition | Inverse signal (higher analyte = lower signal); less intuitive | Small molecules, drugs, hormones, epitope competition |
Need to quantify a protein in a complex sample (serum, cell lysate)? Use sandwich ELISA — dual-antibody recognition provides the highest specificity and widest dynamic range.
Screening antibody titers or serum reactivity? Use indirect ELISA — coat the antigen, apply serum dilutions, detect with a universal secondary antibody.
Measuring small molecules or haptens? Use competitive ELISA — small molecules typically have only one epitope and cannot be “sandwiched.”
Need the simplest, fastest protocol? Use direct ELISA — but accept lower sensitivity.
The capture and detection antibodies must recognize non-overlapping epitopes on the same antigen (otherwise they compete for binding). Ideally, the capture antibody has high affinity for stable surface coating, while the detection antibody is conjugated (biotin-streptavidin-HRP or direct HRP) for signal generation. Matched pair development requires screening multiple clones in a matrix format to identify the best capture–detection combination. AtaGenix provides matched antibody pair screening as part of hybridoma development projects.
Need matched antibody pairs for sandwich ELISA development, or ready-to-use ELISA kits for your target? AtaGenix offers custom ELISA development and abinScience catalog ELISA kits across 400+ targets.
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