Fluorescence immunoassay of octachlorostyrene based on Fo¨rster resonance energy transfer between CdTe quantum dots and rhodamine B

•It proposes a competitive immunoassay platform based on FRET for the detection of octachlorostyrene for the first time.•Unlike assembly of QDs and accepters by covalent conjugation, this electrostatic interaction tends to be simpler.•OCS is quantified based on the fluorescence ratio, the sensor-to-sensor difference is greatly eliminated.•This method has been successfully applied in the detection of octachlorostyrene in water samples.

Octachlorostyrene (OCS), a persistent and bioaccumulative toxicant (PBT), was assayed by fluorescence immunoassay based on the Fo¨rster resonance energy transfer (FRET) between CdTe quantum dots (QDs) and rhodamine B-labeled OCS (RB-OCS). Anti-OCS antibody produced in this lab is adsorbed on a microtiter plate. The RB-OCS competes with OCS for the highly specific immunoreaction with the anti-OCS antibodies adsorbed on the microtiter plate. The solution is then isolated and mixed with CdTe QDs as fluorescent donor which excite the emission of RB-OCS through FRET. As a result, the emission of CdTe QDs at 530 nm decreases, whereas the emission of RB-OCS at 580 nm increases. The ratio of fluorescence intensity at 580 nm to that at 530 nm is proportional to the RB-OCS concentration at a fixed CdTe QDs concentration, and consequently proportional to the OCS concentration. Selective and sensitive responses to OCS are achieved with a linear range of 8–80 nM and a LOD of 3.8 nM. Because OCS is quantified based on the fluorescence ratio, the sensor-to-sensor difference is greatly eliminated, making the proposed method a useful approach for in site scanning of OCS.