Electrochemiluminescent immunosensor based on CdS quantum dots for ultrasensitive detection of microcystin-LR

•An ultrasensitive sandwich-type electrochemiluminescent immunosensor for detection of microcystin-leucine-arginine (MCLR) was fabricated based on gold nanoparticles and CdS quantum dots.•The synthesized CdS quantum dots were labeled on antibody against MCLR as the electrochemiluminescent probe. The prepared electrochemiluminescent immunosensor showed high specificity and stability.•The proposed method which was applied to detect the real samples possesses high selectivity, reproducibility and accuracy.

In this paper, a sandwich-type electrochemiluminescent (ECL) immunosensor for detection of microcystin-leucine-arginine (MCLR) based on gold nanoparticles (GNPs) and CdS quantum dots (QDs) was constructed. Transmission electron microscope image (TEM), photoluminescence spectra, ultraviolet-visible absorption spectra were used to characterize the CdS QDs. The fabrication processes of the immunosensor were characterized via electrochemical impedance spectra (EIS). A strong and stable ECL signal was emitted through the electron-transfer reaction between the electron-injected CdS QDs and reduced products of S2O82− in phosphate buffered solution (PBS, pH 7.4) containing of 0.1 M K2S2O8 and 0.1 M KCl. Under the optimum conditions, the ECL immunosensor possesses a wide linear response to MCLR that ranges from 0.01 to 50 μg/L, with a low detection limit of 0.0028 μg/L. Moreover, selectivity, stability, and reproducibility of the proposed immunosensor were acceptable.