Silver Staining of 2-D Electrophoresis Gels

Silver staining of polyacrylamide gels was introduced in 1979 by Switzer et al. (1 ) and rapidly gained popularity owing to its high sensitivity, ca. 100 times higher than staining with Coomassie blue. However, the first silver-staining protocols were not trouble-free. High backgrounds and silver mirrors were frequently experienced, with a subsequent decrease in sensitivity and reproducibility. This led many authors to suggest improved protocols, so that more than 100 different silver-staining protocols for proteins in polyacrylamide gels can be found in the literature. However, all of them are based on the same principle (see refs. 2 and 3 for details) and comprise more or less four major steps.