Silver staining of proteins in polyacrylamide gels: increased sensitivity by a blue toning

An image amplification of silver-stained proteins in polyacrylamide gels by a blue toning has been developed. Following the silver staining, this technique is fast, simple, requires only stable and inexpensive reagents, and its sensitivity is three- to sevenfold higher than the silver staining alone, and 300- to 700-fold higher than the Coomassie blue. When combined with a silver staining utilizing dithiothreitol (J. H. Morrissey, (1981) Anal. Biochem. 117, 307-310) this method is shown to be uniform in sensitivity for five standard proteins. The blue toning does not affect the linearity of the staining and allows the quantitation of proteins by densitometric evaluation.