ABSTRACT
A number of oxazine dyes give rise to metal complexes which are useful stains, for example, celestine blue, gallamine blue and gallocyanine. Oxazines such as cresyl violet being based on a cationic chromophore and carrying amino substituents, are cationic. Probably the most hydrophilic dyes will be metal complexes such as gallocyanine chrome alum, and the most lipophilic is Nile red, a neutral oxazone. Several dyes are useful because they participate in redox reactions with tissues or biological molecules; for example, resazurin, resorufin. Due to commercial secrecy, many applications of this type are described in the literature as using alamar blue, a proprietary resazurin preparation. Several chemically distinct, though related, oxazines have been sold under the name brilliant cresyl blue. Brilliant cresyl blue has a long history as a vital stain, its introduction as a supravital reticulocyte stain by Levaditi being as long ago as 1901.
