diiiodide-1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine iodide]

DiI iodide1 is one of lipophilic fluorescent stains for labeling membranes and other hydrophobic structures. The fluorescence of these environment-sensitive dyes is greatly enhanced when incorporated into membranes or bound to lipophilic biomolecules such as proteins although they are weakly fluorescent in water.