MitoSpy? mitochondrial localization probes are cell-permeant, fluorogenic chemical reagents that are used for labeling mitochondria in live cells. MitoSpy? NIR DilC1(5) localizes to the mitochondria based on its membrane potential and is useful to indicate cell health as well as for localization. Only useful on live cells, the use of fixatives is not recommended prior to imaging or flow cytometry.