Switcheroo yields photoactivatable dyes

Abstract

A simple new method generates fluorescent dyes of many colors that can be activated by visible light. The approach provides a new set of tools for visualizing how proteins and other molecules behave in living cells without damaging tissue (J. Am. Chem. Soc. 2019, DOI: 10.1021/jacs.9b06237). Most existing photoactivatable dyes are bulky, so they can’t label smaller molecules with good resolution. And they need to be activated with high-energy laser light, which damages DNA and mitochondria, causes proteins to cross-link, and can bleach the dyes’ fluorescence. Broadening the palette of dyes that can be triggered with low-power visible light would be a boon for biological imaging in living tissue. In the new study, Han Xiao of Rice University and his team used a thionating agent called Lawesson’s reagent to switch an oxygen atom in an ordinary, nonphotoactivatable fluorescent dye to sulfur, essentially suppressing the glow. Unleashing the fluorescence simply involves