CEDIA (Cloned Enzyme Donor Immunoassay)
Definition
A homogeneous immunoassay using two inactive fragments of beta-galactosidase, an enzyme donor (ED) fragment conjugated to drug, and an enzyme acceptor (EA) fragment. When free (not antibody-bound), ED and EA spontaneously associate to form active enzyme. Sample drug displaces ED conjugate from antibody, allowing association and raising enzyme activity.
- Full form
- Cloned Enzyme Donor Immunoassay
- Enzyme used
- Beta-galactosidase, split into ED and EA fragments
- Format
- Homogeneous (no wash step)
- Signal logic
- Free ED and EA associate and raise enzyme activity
- Typical use
- Urine drug screening
Common questions
How does CEDIA's signal direction differ from a competitive ELISA?+
In CEDIA, more drug in the sample displaces more ED conjugate from antibody, so signal rises with drug concentration. In many competitive immunoassay formats used for drug screening, signal instead falls as drug concentration rises, so the two techniques must be read in opposite directions.
Why is a homogeneous format like CEDIA useful for high-volume screening?+
Because there is no separation or wash step between bound and free reagent, the assay runs faster and automates easily on standard clinical chemistry analyzers, which suits high-throughput toxicology and workplace screening labs.
Related terms
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