CellBrite™ & MemBrite™ Membrane & Cell Surface Stains
CellBrite™ Cytoplasmic Membrane Stains are lipophilic dyes for simple, non-toxic, stable labeling of membranes in live or fixed cells. Cells can be fixed with formaldehyde before or after CellBrite™ staining. But the staining has poor tolerance for permeabilization or methanol fixation, so CellBrite™ staining is not easily combined with intracellular immunofluorescence (IF) staining. The dyes also do not stain bacteria or yeast. CellBrite™ NIR dyes are CellBrite™ dyes with near-infrared fluorescence compatible with small animal NIR imaging systems.
CellBrite™ Fix and MemBrite™ Fix stains were developed to overcome some of these shortcomings. They are novel covalent stains that can be fixed and permeabilized for IF staining. CellBrite™ Fix Membrane Stains are fluorogenic reactive membrane dyes that rapidly accumulate at the plasma membrane. When they incorporate into lipids, they become fluorescent, and at the same time react covalently with membrane proteins for stable labeling. Staining takes only 15 minutes in a single step with no wash. CellBrite™ Fix stains mammalian cells, yeast, and bacteria.
MemBrite™ Fix Cell Surface Stains do not bind lipids, but label cell surface proteins. MemBrite™ Fix requires a two-step staining protocol with washing, but offers a more extensive choice of dye colors than CellBrite™ Fix. MemBrite™ Fix also can be used to stain yeast. But unlike original CellBrite™ dyes and lectins, CellBrite™ Fix and MemBrite™ Fix cannot be used on cells that are already fixed.
Original CellBrite™ Cytoplasmic Membrane Stains are lipophilic carbocyanine dyes. These dyes undergo an increase in fluorescence when they insert into lipid bilayers. Lipophilic carbocyanine dyes stably label the plasma membrane and other intracellular membranes of cells. They also can be used to stain fixed cells or artificial lipid bilayers.
CellBrite™ Fix Membrane Stains are fluorogenic membrane dyes that react covalently with proteins on the cell surface. They have better water solubility than original CellBrite™ dyes and as a result generally give more even staining of the cell surface compared to original CellBrite™ dyes. CellBrite™ Fix are well retained after fixation and permeabiliation or methanol fixation. However, CellBrite™ Fix dyes cannot be used to stain the plasma membrane of cells after they are already fixed (the dyes stain intracellular membranes of fixed cells).
For all membrane stains, if cells are returned to culture after staining, membrane internalization will occur over time, resulting in predominantly intracellular staining.
Lipophilic carbocyanine dyes like our original CellBrite™ Cytoplasmic Membrane Stains have been used to stain neuronal cells in culture for several weeks, and in vivo for up to a year (see note below). The dyes do not appreciably affect cell viability, and do not readily transfer between cells with intact membranes, allowing cell migration and tracking studies in mixed populations. Staining with the covalent stains CellBrite™ Fix and MemBrite™ Fix lasts up to 48 hours in tissue culture cells (see note below).
Note: Over time, all cell surface stains will be internalized and become intracellular as membranes turn over by endocytosis. The rate of internalization may vary by cell type, rate of membrane turnover, and rate of cell division. In immortalized cells in culture, most of the surface staining becomes internalized over the course of about 24 hours for CellBrite™, CellBrite™ Fix, and MemBrite™ Fix stains.
For an alternative stable and fixable stain for long term cell tracking or tracking cells in mixed cultures, see our ViaFluor® SE Cell Proliferation Dyes. These dyes covalently label intracellular proteins throughout the cell and are non-toxic and fixable.
Biotium’s CellBrite™ Cytoplasmic Membrane Dyes are dye delivery solutions that can be added directly to normal culture media to uniformly label suspended or adherent cells in culture. The PKH dyes are structurally related dyes for cell membrane labeling. But unlike CellBrite™, labeling with PKH dyes requires multiple steps and subjects cells to an iso-osmotic mannitol loading medium that can negatively affect cell membrane integrity and viability.
CellBrite™ Fix dyes also feature rapid and simple labeling in isotonic buffer. Cells can be fixed and permeabilized after labeling with CellBrite™ Fix, unlike original CellBrite™ dyes or PKH dyes, which don’t tolerate detergent.
Cells can be fixed with formaldehyde after labeling with original CellBrite™ or CellBrite™ NIRhttps://biotium.com/product/cellbrite-nir-cytoplasmic-membrane-dye/ dyes. Lipophilic carbocyanine dyes like the CellBrite™ and CellBrite™ dyes have also been used to stain cells or tissues after formaldehyde fixation. Permeabilization of cells with detergents or solvents, or mounting medium containing glycerol may adversely affect staining. Permeabilization with digitonin (10 ug/mL to 1 mg/mL) has been reported to be compatible with lipophilic carbocyanine dye staining.
CellBrite™ Fix Membrane Stains and MemBrite™ Fix Cell Surface Stains belong to a new class of membrane dyes designed to covalently label the cell surface. They can withstand fixation and permeabilization, or fixation with alcohol after labeling of live cells. CellBrite™ Fix and MemBrite™ Fix cannot be used to label the plasma membranes of fixed cells or tissues (the dyes label intracellular membranes and proteins in fixed cells).
It’s common for DiB Loading Buffer (30024B) to solidify into a gel during storage. This does not affect the product, but the buffer must be in liquid form before use. Heat the solidified gel to 50-60°C for 5-10 minutes and vortex periodically until it has formed a clear liquid. DiB Loading Buffer is viscous, so pipet it slowly to ensure the correct volume is added.
You can heat the DiB Cell Labeling Solution to 37°C for 10 minutes or longer, and pipette the solution up and down or vortex to mix completely until is is completely dissolved.