Biotium's CellBrite™ NIR Cytoplasmic Membrane Dyes are ready-to-use dye delivery solutions that can be added directly to normal culture media to uniformly label cells in suspension or adherent cultures. Carbocyanine dyes label cytoplasmic membranes and intracellular membrane structures efficiently and permanently. They have been used as tracers in cell fusion, cellular adhesion, and migration applications due to their properties of low cytotoxicity and high resistance to intercellular transfer. However, the lipophilic nature of these dyes pose an obstacle to uniform cellular labeling. Although structurally related PKH dyes have been developed and optimized for cell labeling, the procedure requires multiple steps and subjects cells to an iso-osmotic mannitol loading medium. A variety of carbocyanine dyes with different optical properties are available, allowing cell populations to be marked with distinct fluorescent colors for identification after mixing. Double labeling can identify cells that have fused or formed stable clusters. CellBrite™ NIR Cytoplasmic Membrane Dyes are novel near-infrared carbocyanine dyes for labeling the cytoplasmic membranes of living cells. Due to their long emission wavelengths, near-infrared cell membrane stains can be used to label cells for near-infrared small animal imaging studies for non-invasive imaging of cell migration and cell homing. The dyes have long 18-carbon hydrophobic tails and an additional water-soluble group. These unique chemical structure elements make the dyes easy to dissolve while providing highly stable cytoplasmic membrane staining, unlike traditional carbocyanine dyes like DiI, DiO, and DiR, which are often difficult to dissolve or prone to precipitation during cell staining. CellBrite™ NIR Cytoplasmic Membrane Dyes are available in the following colors: CellBrite®NIR680 (excitation/emission 683/724 nm), CellBrite®NIR750 (excitation/emission 748/780 nm), NIR770, (excitation/emission 767/806 nm) and NIR790 (excitation/emission 786/820 nm). Biotium offers other CellBrite™ Cytoplasmic Membrane Stains in a variety of colors. CellBrite™ dyes can be used to stain live cells or formaldehyde-fixed cells. Live cells can be fixed in formaldehyde after staining as well. However the staining has poor tolerance for methanol fixation or detergent permeabilization. For membrane stains that withstand fixation with either formaldehyde or methanol, as well as detergent permeabilization, see our CellBrite™ Fix Membrane Stains and MemBrite™ Fix Cell Surface Staining Kits.