Bi-based photocatalysts are widely applied in energy and environment fields by virtue of their excellent oxidation ability. However, there is still no effective method to construct Z-scheme heterojunction and regulate...

H 2 O 2 and polarity are quite important in many physiological and pathological processes, and their relationship is complicated and obscure for researchers. Thus, it is vital and challenging to achieve simultaneous detection of H 2 O 2 and polarity in vivo. Herein, the first naphthalimide−triphenylamine-based dualsite fluorescent probe NATPA is developed for simultaneously imaging intracellular H 2 O 2 and polarity fluctuations. It exhibits excellent sensitivity (LOD = 44 nM), selectivity, and fast response (15 min) to H 2 O 2 and a superior capacity for detecting polarity upon the intramolecular charge transfer (ICT) effect. Besides, the probe displays low cytotoxicity and lipid droplet targeting and is further applied in imaging H 2 O 2 and polarity fluctuations in HepG2 and L-02 cells, so that NATPA is qualified to distinguish cancer cells from normal cells. This research contributes a new design principle for the construction of dual-site fluorescent probes for simultaneously detecting active molecules and polarity.