Fluorescein uptake - (Apr/03/2014 )

Hey, I'm having some trouble getting my myoblasts to take up fluorescein. I'm using the pure dye, and when I dilute it in PBS and treat my cells with it in PBS, they become fluorescent, but when I dilute it in DMEM media they don't..! Additionally, I can't seem to fix my cells and keep them fluorescent - I have tried with both PFA and Ethanol/acetic acid (glacial). 

Do any of you know why this is the case, and if there is any way I can fix my cells (and DAPI-stain them) without losing the fluorescein taken up?

if the only reason you need to fix the cells is to stain their nuclei, you might try Hoechst - it's a live dye.

Could it be that fluorescence is masked by phenol red in the media when you try to look at your cells in DMEM? If so, try some phenol red free medium.