Synthesizing carbon dots with functional preservation strategy as a facile ratiometric fluorescent sensing platform for monitoring hypochlorite in living cells and zebrafish

As an important species of reactive oxygen and a commonly-used water disinfectant, hypochlorite (ClO-) has been reported to be tightly associated with oxidative stress and related diseases. Therefore, developing ClO- sensors, especially the sensors that can detect in a ratiometric fluorescent manner are highly desirable. Herein, a ClO- ratiometric fluorescent sensing platform M-CDs which can respond to ClO- rapidly and precisely was subtly constructed with a detection range of 0.1–50 μM and a low detection limit of 67 nM by simply blending the green fluorescent carbon dots (G-CDs) and red fluorescent carbon dots (R-CDs) with no complicated synthesis and surface modification. Both CDs were legitimately prepared by a functional preservation strategy, and they exhibited different ClO- reactivity due to the inheritance of functional groups and properties of different precursors. The detection mechanism was verified by Mass spectrometry, temperature-dependent fluorescence, fluorescence decay curves and 1H NMR spectra. Besides the excellent performance in water samples, the platform also enables the monitoring of ClO- in living cells and zebrafish, which indicates the sensing system pens up new horizons for the development of ratiometric fluorescent sensing.