Electrochemiluminescence performance of nitroolefin-based fluorescein in different solutions and its application for the detection of cysteine

Electrochemiluminescence (ECL) property of nitroolefin-based fluorescein was investigated and reported for the first time. Its ECL behaviors in acetonitrile (CH3CN) system and aqueous system were studied, respectively. Results indicated that nitroolefin-based fluorescein showed reversible reduction peaks on cycling voltammetric (CV) spectrum and produced ECL emission with the presence of benzoyl peroxide (BPO) as a coreactant in CH3CN solution. Reduction potential peaks of the substance can be observed in water solution in CV, and the intensity of ECL emission is much lower in water than that of in CH3CN solution. However, the ECL property of nitroolefin-based fluorescein can be used for the detection of cysteine (Cys) by using potassium persulfate (K2S2O8) as coreactant in aqueous solution. Under optimum conditions, the ECL intensity has a linear relationship with the concentration of cysteine in the range of 10−9 to 10−8 mol L−1 and a detection limit of 4.2 × 10−10 mol L−1. It has a lower detection limit than the fluorescence method. Our investigation demonstrated that the proposed method provides an elegant platform for fabrication of new generation of biosensors with ultrahighsensitivity, and might have potentially broad applications in amino acids diagnostics and bioassay.