SPI-Chem Toluidine Blue O, CAS# 92-31-9 Light Microscope and Histology Stain
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There is little documentation of any particular specificity. It is, on the other hand, well known as a metachromatic dye and is used for general staining of semi-thin sections of epoxy and other plastic-embedded materials. The metachromatic dyes are often used to help histochemically characterize glycoaminoglycans (GAGs) and other non-neutral polysaccharides, but toluidine blue O is not usually the first choice for such purposes.
It is also widely used in the Alizarin red/Toluidine blue method for bone and cartilage. This stain also works very well with undecalcified bone as reported in J. of Histotechnology 17, 357-359 (1994).
It can be used as a surface stain, as a stain with plastic removed, or on paraffin sections.
Preparation of the stain:
Great care is needed in the mixing of the 1% toluidine blue solution. There are a number of variations on the protocol, but the following is our suggestion, at least for a starting point:
- Saturate with sodium borate (Na2B4O7•10H2O) using 25g in 500 ml water
- Allow to sit for 24 hours at 4° C (39° F)
- Slowly double filter the solution with Whatman No.1 filter paper
- Syringe filter before each use
- Storage conditions: 4° C (39° F). Store in a dark place