A rapidly responding and highly sensitive biosensor for pH-universal detection of ONOO− and its cellular imaging

[Display omitted] •A novel “ESIPT + AIE” based biosensor was fabricated.•It showed a fast (6 s) and ultrasensitive (5.1 nM) response to ONOO− with wide pH value adaptation (3–10).•It was able to visualize ONOO− in living cells with low cytotoxicity. Peroxynitrite (ONOO−) is a highly reactive and short-lived oxidant with low content in cells, and plays an important role in biology. Accordingly, developing a rapid, sensitive, and effective detection approach of cellular ONOO− is very meaningful to further study its biological functions. In this work, a new biosensor BQ for the recognition of ONOO− was facilely synthesized by condensation of 2-hydrazinoquinoline and formylated benzothiazole possessing ‘‘ESIPT + AIE” feature. The probe can be used in a wide range of pH value, and displayed a rapid fluorescence “turn on” response toward ONOO− with low detection limit (5.1 nM) and high selectivity over other competitive substances through ONOO−-triggered oxidative cleavage of C=N double bond. The sensing mechanism of BQ towards ONOO− was proved by 1HNMR and HRMS analysis. Furthermore, the capacity of BQ to detect intracellular ONOO− has been well-demonstrated by fluorescence microscopic imaging experiments, indicating its potential application for investigating the physiological function of ONOO−.