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Fluorescent Brightener 28 disodium salt solution

used as a stain and brightening agent

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Fluostain I, Calcofluor White LRP, Calcofluor White ST, Calcofluor white M2R, Tinopal LPW
Linear Formula:
CAS Number:
Molecular Weight:
MDL number:




25% in water

SMILES string


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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.


  • 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.

Storage Class Code

12 - Non Combustible Liquids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

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Conn's Biological Stains
Kiernan & Horobin
Conn?s Biological Stains (2002)
The Multifunctional Beta-Oxidation Enzyme Is Required for Full Symptom Development by the Biotrophic Maize Pathogen Ustilago Maydis
Jana Klose et at.
Eukaryotic Cell null
Histological and Histochemical Methods: Theory and Practice
J.A. Kiernan
Histological and Histochemical Methods: Theory and Practice (2015)
Candida albicans Biofilm-Defective Mutants
Mathias L.Richard
Eukaryotic Cell null
Mathias L Richard et al.
Eukaryotic cell, 4(8), 1493-1502 (2005-08-10)
Biofilm formation plays a key role in the life cycles and subsistence of many microorganisms. For the human fungal pathogen Candida albicans, biofilm development is arguably a virulence trait, because medical implants that serve as biofilm substrates are significant risk

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