DiD is a far-red fluorescent carbocyanine dye for cell membrane labeling in vivo and in vitro. DiD diffuses laterally to stain the entire cell, allowing it to be used as an anterograde and retrograde tracer of neurons. In intact tissue, the dye does not transfer from labeled to unlabeled cells, but some transfer may occur when the membrane is disrupted, for example, after sectioning. The dye is weakly fluorescent until incorporated into membranes.
DiD can be used with other tracers in dual-color studies, such as DiI or DiO.
DiD is a solid form for the direct application of crystals to membranes.