Trypan Blue

Trypan blue is a diazo membrane-impermeable dye that selectively stains dead cells. The dye can pass the membrane of a dead cell, but not a viable cell’s intact membrane. Once diffused inside, trypan blue binds with intracellular proteins to give an overall bluish color. Known as the dye exclusion method, this technique allows for the staining and microscopic visualization of dead cells versus living, viable cells. The dye can also be used to test for tissue viability in species such as mice.