Trypan blue is a vital stain

Vital stain

A vital stain is a stain that can be applied on living cells without killing them. Vital stains have been useful for diagnostic and surgical techniques in a variety of medical specialties...

 used to selectively colour dead tissues

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 or cells

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 blue. It is a diazo dye.

Live cells or tissues with intact cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

s are not 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. Since live cells are excluded from staining, this staining method is also described as a dye exclusion method. This dye may be a cause of certain birth defects such as encephalocele

Encephalocele

Encephalocele, sometimes known by the Latin name cranium bifidum, is a neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by failure of the neural tube to close completely during fetal...

.

Background & chemistry

Trypan blue is derived from toluidine

Toluidine

There are three isomers of toluidine, which are organic compounds. These isomers are o-toluidine, m-toluidine, and p-toluidine. The o- stands for ortho- , m- stands for meta- , and p- stands for para-...

, that is, any of several isomeric bases

Bases

Bases may refer to:*Bases , a military style of dress adopted by the chivalry of the sixteenth century.*Business Association of Stanford Entrepreneurial Students...

, C₁₄H₁₆N₂, derived from toluene

Toluene

Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...

.
Trypan blue is so-called because it can kill trypanosomes, the parasites that cause sleeping sickness. An analog of trypan blue, suramin

Suramin

Suramin is a drug developed by Oskar Dressel and Richard Kothe of Bayer, Germany in 1916, and is still sold by Bayer under the brand name Germanin.According to the National Cancer Institute there are no active clinical trials...

 is used pharmacologically against trypanosomiasis

Trypanosomiasis

Trypanosomiasis or trypanosomosis is the name of several diseases in vertebrates caused by parasitic protozoan trypanosomes of the genus Trypanosoma. Approximately 500,000 men, women and children in 36 countries of sub-Saharan Africa suffer from human African trypanosomiasis which is caused by...

. Trypan blue is also known as diamine blue and Niagara blue.

Trypan red and Trypan blue were first synthesized by the German scientist Paul Ehrlich

Paul Ehrlich

Paul Ehrlich was a German scientist in the fields of hematology, immunology, and chemotherapy, and Nobel laureate. He is noted for curing syphilis and for his research in autoimmunity, calling it "horror autotoxicus"...

 in 1904.

Uses of trypan blue

Trypan blue is commonly used in microscopy

Microscopy

Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...

 (for cell counting) and in laboratory mice for assessment of tissue viability. The method cannot distinguish between necrotic

Necrosis

Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 and apoptotic

Apoptosis

Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...

 cells.

It may also be used to observe fungal hypha

Hypha

A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...

e and Stramenopiles.

Synonyms

• Azidine Blue 3B
• Benzamine Blue 3B
• Benzo Blue 3B
• Chlorazol Blue 3B
• Diamine Blue 3B
• Dianil Blue H3G
• Direct Blue 14
• Niagara Blue 3B