Hoechst 33342 fluorophor stain for eukaryotic cell nuclei is slightly soluble in water and DMSO up to 10mg/ml. Hoechst 33342 fluorophor stain, more lipophilic than Hoechst 33258, is the cationic bis-benzimide compound with an ethyl end group to aid cell penetration, and is supplied as a powder for the researcher to make their own fresh solution, as the solutions supplied commercially must be stored cold.

This fluorescer has a large Stokes Shift, having excitation maximum circa 350nm and fluorescence emission greater than 510nm when in solution and unbound. Its fluorescence emission is sharply reduced to 461nm when in contact with cells, but fluorescence emission greatly increases, i.e. the quantum yield increases. A very large Stokes Shift is a very useful property, and allows Hoechst 33342 to be used in combination with other cationic and non ionic fluorescent stains with smaller Stokes Shifts. There is no literature evidence of this stain being used to stain anionic materials such as cellulose, lignin or contaminants with carboxyl groups.

This cell-permeable, blue-green fluorescent dye binds to the minor groove of adenine and thymine rich regions in double-stranded DNA and is widely used as a nuclear counterstain in live or fixed cell imaging, fluorescence microscopy, flow cytometry, cell cycle analysis, and apoptosis detection.

A number of other fluorescent stains are available that label DNA and allow easy visualization of the nucleus in interphase cells and chromosomes in mitotic cells, but an advantage of Hoechst 33342 is that it is a membrane penetrant and can stain living cells. This stain is used with co-stains, but some anionic stains may be incompatible and quench fluorescence.

Hoechst AG was a German chemical company with a long history, and was part of I.G. Farben the German dye manufacturing conglomerate until demerged. The Hoechst company merged with Rhone Poulenc in 1999. Prior to the 1997 sale of its optical brightening agent business to Clariant, Hoechst had a reputation for its Optical Brightening Agents for textiles sold under the Hostalux brand name. However, Hoechst 33342 (its 33,342 product) is unsuitable as an optical brightening agent and must only be used by researchers as a fluorophor, as it binds to DNA and must be used safely.

FluoroFinder lists absorbance and emission data of many common and unusual fluorescent compounds including Hoechst 33342

https://app.fluorofinder.com/dyes

Detailed information about Hoechst 33342 is provided by Wikipedia
https://en.wikipedia.org/wiki/Hoechst_stain

Microscope Stain

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This fluorophor is similar to 33258 but is a more lipophilic stain for eukaryotic cell nuclei and is slightly soluble in water and DMSO.

Smiles Key
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