Eosin

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Eosin Y
Eosin B

Eosin is the name of several

histologic stain.[1][2]

Etymology

Eosin was named by its inventor Heinrich Caro after the nickname (Eos) of a childhood friend, Anna Peters.[3]

Variants

Eosin Y solution for staining microscopy slides

There are actually two very closely related compounds commonly referred to as eosin. Most often used is in histology is Eosin Y[1][2] (also known as eosin Y ws, eosin yellowish, Acid Red 87, C.I. 45380, bromoeosine, bromofluoresceic acid, D&C Red No. 22); it has a very slightly yellowish cast. The other eosin compound is Eosin B (eosin bluish, Acid Red 91, C.I. 45400, Saffrosine, Eosin Scarlet, or imperial red); it has a very faint bluish cast. The two dyes are interchangeable, and the use of one or the other is a matter of preference and tradition.

Eosin Y is a tetrabromo derivative of fluorescein.[4] Eosin B is a dibromo dinitro derivative of fluorescein.[5]

Uses

Use in histology

Eosinophilic staining, compared to other patterns when using hematoxylin and eosin (H&E)

Eosin is most often used as a

red blood cells
intensely red.

For staining, eosin Y is typically used in concentrations of 1 to 5 percent weight by volume, dissolved in water or ethanol.[6] For prevention of mold growth in aqueous solutions, thymol is sometimes added.[7] A small concentration (0.5 percent) of acetic acid usually gives a deeper red stain to the tissue.

It is listed as an

class 3 carcinogen
.

Other uses

In his Field with Irises near Arles painting, Van Gogh incorporated red eosin dye into the color of the irises depicted at the bottom of the painting. Due to eosin's tendency to fade, the petals have now attained a blueish hue from their original purple coloration.[8]

Eosin is also used as a red dye in inks; however, the molecule, especially that of eosin Y, tends to degrade over time, leaving behind its bromine atoms, hence causing paint incorporating such a dye to obtain a darker brown tinge over time.

Van Gogh
.

See also

References

  1. ^ a b Lillie, Ralph Dougall (1977). H. J. Conn's Biological stains (9th ed.). Baltimore: Williams & Wilkins. pp. 692p.
  2. ^ a b Bancroft, John; Stevens, Alan, eds. (1982). The Theory and Practice of Histological Techniques (2nd ed.). Longman Group Limited.
  3. JSTOR 3107005
    .
  4. SMILES
    structure is O=C5C(Br)=C2O C1=C(Br)C([O-]) =C(Br)C=C1C(C4=C (C([O-])=O)C=C C=C4)=C2C=C3Br.
  5. SMILES
    structure is O=C5C(Br)=C2O C1=C(Br)C([O-]) =C([N+]([O-])=O) C=C1C(C4=C(C([O-]) =O)C=CC=C4)=C2 C=C3[N+]([O-])=O.
  6. ^ "Haematoxylin Eosin (H&E) staining". protocolsonline.com. 11 April 2010. Retrieved 22 April 2018.
  7. PMID 6769391
    .
  8. ^ a b "Van Gogh's Fading Colors Inspire Scientific Inquiry".

External links

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