Hi Alessandra!

We had a good experience with fixed MitoTracker loaded cells. Invitrogen recommends fixing with the 3.7% formaldehyde, but I am pretty sure that your method should work too. Fixed samples should be fine in a mounting media (liquid or set) covered in aluminum foil at +4 for several weeks without any significant signal decrease. For long-term storage, I recommend freezing it.

Good luck with microscopy!

Hello Alessandra,

As long as there is no quenching of the fluorescent dyes, you should be able to store them for several weeks. Just ensure they are covered in aluminium foil or stored appropriately in dark (sometimes exposure to light leads the fluorescence dyes to begin quenching and the stain becomes very faint after prolonged (improper) storage.

Best of luck !

Lots of experience using it over years and years. The dye binds to mitochondrial proteins via a chloromethyl group, so it is very stable and won't have any significant off-rate. So it will be retained for as long as the proteins it is bound to are retained. Formaldehyde is best because it crosslinks those proteins in place. With that fixation, I've stored labeled cells for weeks at 4C or months at -20C (in a cryoprotectant) or years if mounted in Cytoseal 60 (our FluoCells #1 slides have this dye and mounting). Methanol should work, but it just precipitates proteins, not crosslinking. Still, I expect long-term retention, particularly if stored cold.

Thank you all. So, if I have understood correctly, I can store my fixed and labeled cells at 4 °C without losing the MitoTracker fluorescent signal