A simple Schiff base was prepared by mild condensation reaction between a coumarin fluorescent group and diaminomaleonitrile, and it could serve as an excellent fluorescent probe for fast detection of ClO- with high selectivity and sensitivity. Along with addition of ClO-, this probe fleetingly showed noteworthy "turn-on" phenomenon accompanied by an increase of fluorescence intensity and the change of emission color from yellow to blue. This change of fluorescence is so significant that it can be observed by the naked-eye under a handheld ultraviolet light of 365 nm. However, other common reactive oxygen species exhibited no or very little fluorescent response under the same conditions. The limit of detection of this probe toward ClO- had a sensitivity feature as low as 9.6 nM. On account of these excellent features of short response time, remarkable fluorescence and color signal changes, high sensitivity and selectivity, this probe was effectively used for the fluorescence detection of ClO- in water samples. The values of the relative standard deviation were between 1.41% and 2.91%. More importantly, this probe displays excellent imaging capability in cytoplasm as well as very low cell toxicity and was unambiguously applied to image ClO- in living cells. Graphical abstract A fluorescent probe based on coumarin for detection of ClO- was successfully developed, which can besuccessfully used for the detection of ClO- in living cells and in water sample because of the excellentfeatures including short response time, remarkable fluorescence and color signal changes, high sensitivityand selectivity.
Keywords: Cell imaging; Coumarin; Fast response; Fluorescent probe; Hypochlorite.