DiIiodide1,1'-Dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine iodide]

DiI iodide is a lipophilic, environment-sensitive fluorescent dye used to label cellular membranes and hydrophobic structures. Its fluorescence is weak in aqueous solutions but becomes strongly enhanced upon integration into lipid bilayers or binding to lipophilic proteins. This property makes it a valuable tool for in vitro and in vivo imaging applications in cell biology and neuroscience research.