1,2-dioleoyl-rac-glycerol PEG2000 fluorescein (DOG-PEG2000-FITC) is a diacyl glycerol lipid fluorescein conjugate that contains no phosphate linkage. Oleic acid is a un-saturated C18 lipid that can interact well with cell membrane bilayer. Fluorescein modified dipalmitoyl glycerol has strong green fluorescence with exitation/emission at 494 nm/515 nm. PEG linker between dioleoyl glycerol and fluorescein offers better water solubility and flexible linker structure. DOG-PEG-fluorescein thus can be an excellent membrane imaging agent.