Trypan blue

Trypan blue

Trypan blue is a vital stain that is used to colour dead tissues or cells blue. It is a diazo dye.

Live cells or tissues with intact cell membranes will not be coloured. Since cells are very selective in the compounds that pass through the membrane, in a viable cell trypan blue is not absorbed; however, it traverses the membrane in a dead cell. Hence, dead cells are shown as a distinctive blue colour under a microscope.

Uses of trypan blue

Observation with an optical microscope of Hyaloperonospora parasitica within a leaf of Arabidopsis thaliana by using the trypan blue staining.

Trypan blue is commonly used in microscopy (for cell counting) and in laboratory mice for assessment of tissue viability. The method cannot distinguish between necrotic and apoptotic cells.

It is also useful to observe hyphea of fungi and Stramenopiles.

Some examples

Source of trypan blue

Trypan blue is derived from tolidine, that is, any of several isomeric bases, C₁₄H₁₆N₂, derived from toluene.

The name

Trypan blue is so-called because it can kill trypanosomes, the parasites that cause sleeping sickness. The dye is also known as diamine blue and Niagara blue.

History

Trypan red and Trypan blue was first synthesized by the German scientist Paul Ehrlich in 1904.

Protocols of use

Place 500 ul of suitable cells in appropriate tube add 500 ul 0.4% Trypan blue and gently mix, let stand for 5 minutes at room temperature. Place 10 ul of stained cells on haemocytomter and count the number of viable cells (unstained) to dead (stained)

CAS and SMILES

Its CAS number is 72-57-1 and its SMILES structure is CC1=CC(C3=CC(C) =C(N=NC5=C(S(=O) (O)=O)C=C(C=C (S(=O)(O)=O)C=C6N) C6=C5O)C=C3)=C C=C1N=NC2=C(O) C(C(N)=CC(S(=O) (O)=O)=C4)=C4 C=C2S(=O)(O)=O.

References

• Chapter "Detection of Caspase Activation Combined with Other Probes of Apoptosis", Eurekah Bioscience Collection, NCBI bookshelf
• Protocol for use of the dye from Northwestern University (PDF)