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Trypan blue
Names
	IUPAC name (3Z,3'Z)-3,3'-[(3,3'-dimethylbiphenyl-4,4'-diyl)di(1Z)hydrazin-2-yl-1-ylidene]bis(5-amino-4-oxo-3,4-dihydronaphthalene-2,7-disulfonic acid)
Identifiers
CAS Number	72-57-1 (tetrasodium salt) ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:78897 ;
ChEMBL	ChEMBL1640 ;
ChemSpider	10482308 ;
ECHA InfoCard	100.000.715
KEGG	C19307 ;
PubChem CID	5904246;
UNII	I2ZWO3LS3M ;
CompTox Dashboard (EPA)	DTXSID4026268 ;
	InChI InChI=1S/C34H28N6O14S4.4Na/c1-15-7-17(3-5-25(15)37-39-31-27(57(49,50)51)11-19-9-21(55(43,44)45)13-23(35)29(19)33(31)41)18-4-6-26(16(2)8-18)38-40-32-28(58(52,53)54)12-20-10-22(56(46,47)48)14-24(36)30(20)34(32)42;;;;/h3-14,41-42H,35-36H2,1-2H3,(H,43,44,45)(H,46,47,48)(H,49,50,51)(H,52,53,54);;;;/q;4+1/p-4/b39-37+,40-38+;;;; Key: GLNADSQYFUSGOU-GPTZEZBUSA-J ; InChI=1S/C34H28N6O14S4.4Na/c1-15-7-17(3-5-25(15)37-39-31-27(57(49,50)51)11-19-9-21(55(43,44)45)13-23(35)29(19)33(31)41)18-4-6-26(16(2)8-18)38-40-32-28(58(52,53)54)12-20-10-22(56(46,47)48)14-24(36)30(20)34(32)42;;;;/h3-14,41-42H,35-36H2,1-2H3,(H,43,44,45)(H,46,47,48)(H,49,50,51)(H,52,53,54);;;;/q;4+1/p-4/b39-37+,40-38+;;;; Key: GLNADSQYFUSGOU-WLILTGDCBQ; Key: GLNADSQYFUSGOU-GPTZEZBUSA-J;
	SMILES [Na+].[Na+].[Na+].[Na+].[O-]S(=O)(=O)c6cc1cc(cc(N)c1c(O)c6/N=N/c2ccc(cc2C)c5ccc(/N=N/c4c(cc3cc(cc(N)c3c4O)S([O-])(=O)=O)S([O-])(=O)=O)c(C)c5)S([O-])(=O)=O;
Properties
Chemical formula	C34H24N6Na4O14S4
Molar mass	872.88
Appearance	deep blue in aqueous solution
Melting point	> 300 °C (572 °F; 573 K)
Solubility in water	10mg/ml
Solubility	20 mg/mL in methyl Cellosolve, and 0.6 mg/mL in ethanol
Pharmacology
ATC code	S01KX02 (WHO)
Hazards
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	6200 mg/kg (oral, rat)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Trypan blue is an azo dye. It is a direct dye for cotton textiles.^[3] In biosciences, it is used as a vital stain to selectively colour dead tissues or cells blue.

Live cells or tissues with intact cell membranes 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 appear 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.

Background and chemistry

Trypan blue is derived from toluidine, that is, any of several isomeric bases, C₁₄H₁₆N₂, derived from toluene. Trypan blue is so-called because it can kill trypanosomes, the parasites that cause sleeping sickness. An analog of trypan blue, suramin, is used pharmacologically against trypanosomiasis. Trypan blue is also known as diamine blue and Niagara blue.

The extinction coefficient for trypan blue is 6⋅10⁴ M⁻¹ cm⁻¹ at 607 nm in methanol.^[4]

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

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.^[5] The method cannot distinguish between necrotic and apoptotic cells.

It may be used to observe fungal hyphae^[6] and stramenopiles.

Trypan blue is also used in ophthalmic cataract surgery to stain the anterior capsule in the presence of a mature cataract, to aid in visualization, before creating the continuous curvilinear capsulorhexis. In keratoplasty, trypan blue can be used to stain the posterior stromal fibers during deep lamellar endothelial keratoplasty (DLEK) and to stain the endothelium in Descemet's stripping endothelial keratoplasty (DSEK). Trypan blue is used in vitreoretinal surgeries also.^[7]

In early 20th century, the existence of a barrier protective toward the brain (blood brain barrier) was inferred, based on the observation that injection of trypan blue in animals led to whole‐body staining except for the brain and spinal cord.

Synonyms

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

References

^ PubChem. "CID 9562061 | C34H24N6Na4O14S4 - PubChem". Pubchem.ncbi.nlm.nih.gov. Retrieved 2022-04-19.
^ "Trypan Blue Powder Cell Viability Gold Standard Sigma-Aldrich". Merck.
^ Klaus Hunger; Peter Mischke; Wolfgang Rieper; Roderich Raue; Klaus Kunde; Aloys Engel (2005). "Azo Dyes". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_245. ISBN 978-3527306732.
^ "Sigma-Aldrich, 60% Trypan Blue, Product page". Retrieved 2015-07-15.
^ Strober, W (May 2001). "Trypan Blue Exclusion Test of Cell Viability". Current Protocols in Immunology. Appendix 3 (1): Appendix 3B. doi:10.1002/0471142735.ima03bs21. ISBN 978-0471142737. PMID 18432654.
^ Nowicki, Marcin; et al. (15 May 2013), "A simple dual stain for detailed investigations of plant-fungal pathogen interactions", Vegetable Crops Research Bulletin, 77 (1): 61–74, doi:10.2478/v10032-012-0016-z
^ "Trypan Blue Dye: Capsular Staining for Cataract Surgery and More". American Academy of Ophthalmology. 1 April 2006.