DAB reacts with HRP to yield an insoluble brown-colored end product. The brown precipitate is insoluble in alcohol and other organic solvents making it an ideal substrate for immunohistochemical staining that requires the use of traditional counterstains and mounting mediums. It is also ideal for electron microscopy. Many enhancement methods have been reported for DAB involving different buffer conditions, the addtion of metal ions and post-treatment applications.^1-7

The major disadvantage of using all of the DAB substrates is the necessity to immediately use the substrate, because it begins a reaction process upon the addition of hydrogen peroxide. This results in increased background color of the substrate. Pierce offers non-enhanced DAB in two formats: 10 gm crystalline format and the DAB Substrate Kit. The Pierce DAB Substrate Kit includes a 10X solution of DAB and Pierce's unique Stable Peroxide Substrate Buffer. The resulting precipitate is brown that does not fade as quickly as other HRP precipitating substrates. This kit is offered in a liquid format, so there is less handling of a suspected carcinogen.

References:

1. Malmgren, L. and Olsson, Y. (1977). J. Histochem. Cytochem. 25, 1280-1283.
2. Straus, W. (1982). J. Histochem. Cytochem. 30, 491-493.
3. Adams, J.C. (1977). Neuroscience 2, 141-145.
4. Adams, J.C. (1981). J. Histochem. Cytochem. 29, 775.
5. Hsu, S. and Soban, E. (1982). J. Histochem. Cytochem. 30, 1079-1082.
6. De Jong, A.S., et al. (1985). Histochem. J. 17, 1119-1130.
7. Scopsi, L. and Larson, L.I. (1986). Histochemistry 84, 221-230.