A highly responsive, sensitive NIR fluorescent probe for imaging of superoxide anion in mitochondria of oral cancer cells.

Superoxide anion (O(2)(*-)) is an important biomarker for reactive oxygen species (ROS) generated through physiological and pathological processes. However, due to the short half-life of O(2)(*-) and high autofluorescence of cell tissues, in situ real-time tracking and monitoring of endogenous O(2)(*-) can be difficult. In this paper, a fluorescent probe IFP-O(2) was developed to detect endogenous O(2)(*-) in cells. The probe could instantaneously react with O(2)(*-) to produce fluorescence off-on effect; its detection limit was as low as 10 nM. Cell experiments also showed that the probe had low toxicity and mitochondrial targeting ability. The article presents, for the first time, a probe that can be employed to measure endogenous O(2)(*-) in oral cancer Cal-27 cells and is a promising tool for monitoring and evaluating apoptosis.