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.