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.