A fluorescence “turn-on” probe for the respective ratiometric detection of hypochlorite and cysteine

As abnormal levels of hypochlorous acid (HClO) and cysteine (Cys) are associated with some diseases, it is of great importance to detect them accurately. In this work, new carbon dots (N-CDs) for respectively ratiometrically determining HClO and Cys via a “turn-on” mode were prepared. A good linear relationship was obtained between the F548/F640 values and the concentration of HClO in the range of 90–800 μM, with a limit of detection (LOD) of 2.17 μM. By plotting the F640/F548 values against the Cys concentration, a good linear relationship was obtained in the range of 170–900 μM, with a calculated LOD of 6.63 μM. Furthermore, the response mechanisms of the N-CDs towards HClO and Cys were studied systematically. Compared with reported fluorescent probes that can respectively or sequentially detect two types of small molecules, this “turn-on” luminescence nanosensor has low background interference, so it holds great potential for use in the diagnosis of HClO and Cys correlated diseases.