Trypanblau

Trypanblau, commonly known in English as Trypan blue, is a vital dye used to assess cell viability. In German-language sources the term Trypanblau is used; the English term arises from early use for staining non-viable cells. It is a water-soluble azo dye that cannot cross intact cell membranes, so viable cells exclude the dye while dead or damaged cells take it up and appear blue under light microscopy.

In a typical viability assay, cells are mixed 1:1 with a 0.4% Trypan blue solution to yield about a 0.2% final dye concentration, then loaded onto a hemocytometer for counting. Live (unstained) and dead (blue) cells are counted to derive viability. The method is widely used in mammalian cell culture, yeast, fungi, and other cell suspensions to estimate viability prior to experiments or before passaging.

Limitations and considerations include that the method reports membrane integrity rather than all functional states of the cell; early apoptotic cells or cells with transient membrane compromise may be misclassified. Staining can be influenced by temperature, pH, and incubation time, so results should be interpreted cautiously and often complemented with additional assays for a more complete assessment of viability.

Safety and handling: Trypan blue is primarily used in research laboratories. Handle with appropriate personal protective equipment and dispose of dye-containing waste according to local regulations.