We report the discovery of a fluorogenic
dye, N1,N3-di(2-aminidonaphthalen-6-yl)
propane-1,3-diamine, MitoBlue, which selectively stains functional
mitochondria while displaying low toxicity, bright blue emission,
and high resistance to photobleaching. Additionally, we show that
a biotin-labeled MitoBlue derivative can be used as a handle for the
delivery of streptavidin-tagged species to the mitochondria.