A ratiometric fluorescent probe based on oxabenzofluorene structure for the detection of peroxynitrite in mitochondria

As a potent reactive oxygen species (ROS), peroxynitrite (ONOO-) is produced when superoxide anions (O2 center dot- ) react with nitric oxide (NO). This molecule has been demonstrated to be closely linked to the progression of numerous diseases. Peroxynitrite is highly reactive and quite unstable with a very short half-life, which is primarily found within mitochondria. Therefore, creating a mitochondria-targeted fluorescent probe that can selectively detect peroxynitrite is of great importance. In this work, a ratiometric fluorescent probe RHON is designed to detect ONOO-both sensitively and selectively. The probe, featuring an oxabenzofluorene-based structure, was efficiently synthesized in a few short steps. After the addition of ONOO-, the pinkish-purple colour of the probe solution gradually disappeared and finally became colourless. Simultaneously, a substantial blue shift was observed in the fluorescence emission, covering a range of 115 nm. After thorough evaluations, the probe was found to have outstanding selectivity and sensitivity toward ONOO-.Impressively, it can reach an extremely low detection limit of 0.11 nM, and its response time is quite rapid, approximately 1 min. Furthermore, RHON exhibits outstanding biocompatibility. Moreover, the exogenous ONOO-present in mitochondria of living cells could be successfully detected by this probe. This successful application vividly demonstrates the great potential of RHON in the field of biological applications.