A Fluorescent Sensor for Imaging Reversible Redox Cycles in Living Cells

We report the synthesis, properties, and biological applications of Redoxfluor-1 (RF1), a new fluorescent sensor for imaging reversible oxidation−reduction cycles in aqueous solution and in living cells. RF1 is comprised of a fluorescein reporter coupled to a disulfide/dithiol switch. The green fluorescent sensor features a reversible response to multiple oxidation or reduction events, a >50-fold fluorescence dynamic range, and excitation and emission profiles in the visible region to minimize cellular damage and autofluorescence. Confocal microscopy experiments show that RF1 can visualize multiple cycles of oxidation and reduction within living cells, establishing the potential value of this approach for probing dynamic oxidation biology events in natural systems.