A mitochondrion targetable dimethylphosphorothionate-based far-red and colorimetric fluorescent probe with large Stokes shift for monitoring peroxynitrite in living cells

Peroxynitrite (ONOO-) is a biological oxidant that is related to numerous physiological and pathological processes. An overdose of ONOO- is the cause of various serious diseases. Some evidence demonstrates that mitochondria are the major sites of ONOO- production. Therefore, monitoring mitochondrial ONOO- is important to understand the related pathological processes in living systems. Herein, a colorimetric and far-red fluorescent sensing probe (PCPA) for the determination of ONOO- was constructed based on a dicyanoisophorone skeleton using dimethylphosphorothionate as the recognition group and pyridine salt as the mitochondrion-targeting unit. PCPA showed a far-red fluorescence response to ONOO- accompanied by a distinct color change from colorless to yellow via the ONOO- induced deprotection of dimethylphosphorothionate. In addition, PCPA exhibited a large Stokes shift (200 nm), high selectivity detection and high sensibility (LOD = 39 nM). Furthermore, PCPA was successfully employed for imaging ONOO- and tracing ONOO- in mitochondria. PCPA presents a new recognition group and has potential applications in the biology field.