Bis-(phenylselenide) based turn-on fluorescent probe for rapid, perceptible and selective detection of superoxide anion in human colon cancer cells

Superoxide anion is a type of reactive oxygen species (ROS) obtained by one-electron reduction of an oxygen molecule. It temporarily resides in the mitochondria before spreading throughout the cell and in human it regulates many signal transduction processes. Since increased levels of superoxide can cause permanent destruction to human bodies, the discovery of an effective method is significantly important for its selective and sensitive detection. This work explores a new “turn-on” fluorescence probe, Se-BODIPY-Se, which was synthesized and characterized by 1 H, 13 C, 77 Se, 11 B, and 19 F NMR spectroscopy, LCMS, and single-crystal XRD. The strategy of the probe was based on the photo-induced electron transfer (PET) mechanism between phenylselenide as an electron donor and BODIPY as an electron acceptor moiety. The fluorescence could be restored as a result of the termination of the PET process by the oxidation of selenium when treated with superoxide. The probe presented a high selectivity toward superoxide rather than other ROS, metal ions, biothiols, and amino acids, with a 63-fold marked fluorescence enhancement at 518 nm. The probe operates at physiological pH (7.4), achieving a detection limit down to 31 nM. Furthermore, it selectively detects superoxide anion in the HCT-116 cell line with a 7.4-fold increase in fluorescence intensity, indicating its potential application in live cancer cell imaging.