Merck, 910090-20ML, Fluorescent Brightener 28 disodium salt solution

General description
Fluorescent Brightener 28, also known as Calcofluor White M2R or Fluostain I, is a large, anionic, stilbene derivative of 4,4’-diaminostilbene-2,2’-disulphonic acid. It is a non-specific fluorochrome that binds with cellulose and chitin contained in the cell walls of fungi and other organisms and is used as a stain and fluorescent brightening agent. It exhibits an absorption maximum of 350 nm in methanol and fluoresces blue-white when excited in the violet or near ultraviolet. It bears additional triazinyl and phenyl aromatic groups. The dianionic sulfonate is hydrophilic. It is commercially available as a disodium salt.
Application
Fluorescent Brightener 28 is used in microscopy as fluorochromes, especially to visualize plant tissues by binding to cellulose.
It is used in microbiology for staining pathogenic fungi, fungal cell walls, Candida albicans biofilms, for the automated counting of bacteria and spores, and as a viability stain.
It is a rapid method for the detection of many yeasts and pathogenic fungi such as Microsporidium, Acanthamoeba, Pneumocystis, Naegleria, and Balamuthia species.
It is used industrially as a fluorescent brightening agent for cellulose and polyamide fabrics, paper, detergents, and soaps.
It has been used in the identification and study of the structure and biosynthesis of chitin from the freshwater sponge Spongilla lacustris, and to elucidate the location of chitin in skeletal structures.

Biochem/physiol Actions
The extended molecule of Calcofluor white M2R binds to cellulose but does not enter living cells, and therefore can be used to visualize plant tissues and viable cells. It absorbs ultraviolet radiation to emit blue light and exhibits enhanced fluorescence when bound to chitin.
Features and Benefits
Facilitates rapid detection of many pathogenic yeasts and fungi.
As a brightening agent, its addition can offset the tendency of white materials to yellow with age.