CalcofluorWeiß

Calcofluor White, also known as Calcofluor Weiß, is a fluorescent dye used in light and fluorescence microscopy to stain structural polysaccharides such as cellulose and chitin in plant and fungal cell walls. When exposed to ultraviolet or near-UV light, the bound dye emits a blue fluorescence, allowing clear visualization of cell walls against surrounding material.

The dye binds to β-1,3 and β-1,4 glycosidic linkages found in cellulose and chitin. Calcofluor White is often used in conjunction with sample clearing methods or mounting media and can be applied as a stain for smears or tissue sections. A common variant, Calcofluor White M2R, is widely used in mycology and clinical microbiology for fungal detection.

Applications include rapid screening for fungal elements in clinical specimens (such as skin scrapings, nail clippings, and respiratory samples), environmental samples, and plant tissues where cell walls are prominent. It is valued for producing strong, high-contrast fluorescence of fungal hyphae, spores, and cellulose-containing structures.

Advantages of Calcofluor White include its simplicity and the bright, easily detectable fluorescence it provides under appropriate illumination. Limitations include non-specific staining of plant cell walls, potential autofluorescence of some materials, and the need for a fluorescence-capable microscope with UV or near-UV excitation. The stain does not distinguish fungal species; additional methods are required for identification.

Safety and handling follow standard chemical-dye precautions: use gloves and eye protection, work in a well-ventilated area, avoid inhalation or ingestion, and dispose of waste according to local regulations.