A reverse ELISA based on quantum dot-labeled TetR for rapid detection of tetracycline

The overuse of tetracycline (TC) a novel reverse ELISA assay integrating quantum dots (QDs) with an allosteric transcription factor (TetR) was developed for rapid tetracycline (TC) detection. Specifically, biotin-modified double-stranded DNA (dsDNA) was immobilized on a streptavidin-coated 96-well plate, after which QD-TetR conjugates were added. In the presence of TC, the QD-TetR conjugate binds TC and undergoes allosteric changes that result in its dissociation from the dsDNA. The developed QD-TetR-based reverse ELISA achieved quantitative TC detection within a linear dynamic range of 0.05-100 μM in just 5 min, with a method detection limit of 0.02 μM. The recoveries ranged from 93.43% to 106.6% for actual samples (seawater, sewage, milk, and honey) detection. Furthermore, on-site semi-quantitative detection of TC in actual samples was achieved across a concentration range 0.5-500 μM. The results were validated with commercial ELISA kits, indicating strong potential for monitoring TC residues in environmental and food samples.