A specific AIE and ESIPT fluorescent probe for peroxynitrite detection and imaging in living cells

Developing specific and sensitive method for endogenous peroxynitrite (ONOO^-) in living systems is valuable to understand its various pathological events. In this work, a simple and novel fluorescent probe (HPP) based on aggregation induced emission (AIE) as well as excited state intramolecular proton transfer (ESIPT) processes for endogenous ONOO^- detection was constructed containing a diphenylphosphinate as the reactive site and a salicylaldehyde azine as the fluorophore. The probe showed specific fluorescence turn-on response toward ONOO^- owing to the diphenylphosphinate group of HPP reacted with ONOO^-, releasing the salicylaldehyde azine with both AIE and ESIPT characteristics. In addition, the probe exhibited a large Stokes shift, an excellent light-up ratio, high selectivity and excellent sensitivity with a low detection limit of 8 × 10^-8 M for endogenous ONOO^-. Moreover, the probe could be applied to bioimaging of endogenous ONOO^- in live cell, which demonstrated the probe can be used as effective tool for investigation of ONOO^- in biological systems.