Neutral red ( pH indicator)
below pH 6.8
above pH 8.0
Neutral Red (or toluylene red, Basic Red 5, or C.I. 50040) is a eurhodin dye used for staining in histology. It stains lysosomes red. It is used as a general stain in [1 ] histology, as a counterstain in combination with other dyes, and for many staining methods. Together with Janus Green B, it is used to stain embryonal tissues and supravital staining of blood. Can be used for staining Golgi apparatus in cells and Nissl granules in neurons.
microbiology it is used in the MacConkey agar to differentiate bacteria for lactose fermentation.
Neutral red can be used as a
vital stain. Live cells will incorporate neutral red into their lysosomes. As cells begin to die, their ability to incorporate neutral red diminishes. Thus loss of neutral red uptake corresponds to loss of cell viability. [2 ]
It is also used to stain cell cultures for
plate titration of viruses. [2 ]
Neutral Red is added to some
growth media for bacteria and cell cultures. It usually comes as a chloride salt.
Neutral Red acts as a
pH indicator, changing from red to yellow between the pH 6.8-8.0.
References [ edit ]
^ Winckler, J. Vital staining of lysosomes and other cell organelles of the rat with neutral Red. Prog. Histochem. Cytochem. 6, 1–89 (1974).
^ a b RepettoG, del Peso A, Zurita JL. Neutral red uptake assay for the estimation of cellviability/cytotoxicity. Nat Protoc. 2008;3(7):1125–1131.doi:10.1038/nprot.2008.75.