Ultrasensitive Determination of Microcystin-Leucine-Arginine (MCLR) by an Electrochemiluminescence (ECL) Immunosensor with Graphene Nanosheets as a Scaffold for Cadmium-Selenide Quantum Dots (QDs)

In order to satisfy the needs for the trace microcystins in water, a novel electrochemiluminescence (ECL) immunosensor was developed based on a dual signal amplification strategy. A MoS2-Au hybrid nanocomposite served as the matrix to add a large number of active-sites, and graphene nanosheets were employed as the scaffold to capture cadmium-selenide quantum dots (CdSe QDs). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet-visible absorption spectroscopy and photoluminescence spectroscopy were used to characterize these materials. The fabrication of the immunosensor was performed by electrochemical impedance spectroscopy (EIS). Under the optimum conditions, a strong ECL signal was obtained from immunosensor that was approximately 7-fold higher than from an immunosensor with a pure CdSe QDs probe. The ECL immunosensor possesses a wide linear response to microcystins-LR (MCLR) from 0.005 to 100 mu g/L with a low detection limit of 0.0032 mu g/L. Moreover, the immunosensor exhibited good selectivity, stability, and reproducibility for MCLR.

Automated summary

The ECL immunosensor developed based on dual signal amplification strategy utilizing MoS2-Au hybrid nanocomposite and graphene nanosheets for CdSe QDs capture successfully achieved trace microcystins detection in water with wide linear response range, as well as good selectivity, stability, and reproducibility for MCLR.