An abbreviated procedure for Bio-Rads silver stain is presented here, assuming a gel 0.75 to 1.0 mm thick. Times are longer for thicker gels and shorter for thinner gels. See the package insert for the complete procedure.
Photochemical vs. Silver Diammine Stains
Two silver stains are generally used: diammine, or ammoniacal, types,54 and those adapted from photographic chemical development processes.55 Silver diammine types require that gels be soaked first in basic silver diammine, followed by acid formaldehyde image development. Chemical stains require an initial gel soak in a weakly acidic silver nitrate solution, and development in alkaline formaldehyde. Prior to the silver nitrate step, gels are primed with a reducing agent such as dithiothreitol or an oxidizing reagent such as permanganate or dichromate. Dichromate (Bio-Rad) is most desirable, because images obtained have higher sensitivity and lowest background. Dithiothreitol generates signals of lower sensitivity, while permanganate generates higher backgrounds.
Diammine silver stains suffer from many disadvantages. Reagents are not
stable and must be made fresh prior to staining. Reaction products are
potentially explosive. Reaction times are lengthy in comparison to photochemical
methods. Histochemical silver stains cannot be combined with Coomassie
stains, fluorography, or autoradiography, and gels