Carbocyanine dyes label cytoplasmic membranes and intracellular membrane structures efficiently and permanently (1). They have been used as tracers in cell-cell fusion (2,3), cellular adhesion (4,5), and migration (6) applications due to their properties of low cytotoxicity and high resistance to intercellular transfer. However, the lipophilic nature of these dyes posed 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 (7,8). Biotium’s CellBrite™ 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. 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 (9). 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™ NIR680 Cytoplasmic Membrane Dye has emission at the far-red/near-infrared spectral boundary, and is compatible with both confocal microscopy and near-infrared imaging systems. Longer wavelength CellBrite™ NIR dyes also can be imaged by confocal microscopy using 640 nm excitation for evaluation of cell labeling prior to small animal injection, however the sensitivity of detection using confocal microscopy will be lower compared to near-infrared imaging. [table “10” not found /]
Biotium offers other CellBrite™ Cytoplasmic Membrane Dyes in a variety of colors.