Design of a phosphinate-based fluorescent probe for superoxide detection in mouse peritoneal macrophages

3',6'-Bis(diphenylphosphinyl)fluorescein (PF-1) was synthesized as a highly selective and sensitive fluorescent probe for imaging O2(center dot-) in living cells. The design strategy for the probe was based on the nucleophilic mechanism Of O-2(center dot-) to mediate deprotection of this probe to give fluorescein. Upon reaction with O2(center dot-) the probe exhibits a strong fluorescence response and high selectivity for O2(center dot-) over other reactive oxygen species and some biological compounds. The phosphinate-based probe, as a new fluorescent reagent, is cell-permeable and can detect micromolar changes Of O-2(center dot-) concentrations by using confocal microscopy in living cells. The unique combination of good selectivity, high sensitivity, good water solubility, and rapid reactivity establishes the potential value of the probe for facilitating investigations of the generation, metabolism, and mechanisms of superoxide-mediated cellular homeostasis and injury.