Silver-staining of proteins in polyacrylamide gels: a general overview

On the basis of the physico-chemical principles underlying silver-staining of proteins, which are recalled in this paper, several methods of silver-staining of proteins after SDS electrophoresis in polyacrylamide gels or isoelectric focusing were tested. The most valuable protocols are presented in this report, including standard methods for unsupported gels and new methods devised for thin (0.5 mm) supported gels for SDS electrophoresis or isoelectric focusing and for staining of small peptides. Generally speaking, the most rapid methods were found to be less sensitive and less reproducible than more time-consuming ones. Among the long methods, those using silver-diammine complex gave the most uniform sensitivity. They require however special home-made gels and cannot be applied to several electrophoretic systems (e.g. systems using tricine or bicine as the trailing ion, or isoelectric focusing in immobilized pH gradients). For these reasons, protocols based on silver nitrate are of a more general use and might be favored. Future trends for silver-staining will also be discussed.

💡 Research Summary

This paper provides a comprehensive overview of silver staining of proteins in polyacrylamide gels, beginning with the physicochemical principles that underlie the technique and moving through a systematic evaluation of several staining protocols. The authors first revisit the basic chemistry: silver ions (Ag⁺) interact preferentially with thiol (‑SH) and amino (‑NH₂) groups on proteins, and upon reduction they form metallic silver particles that give the characteristic brown‑black bands. The rate and uniformity of this reduction depend on pH, temperature, silver concentration, and the choice of reducing agent (commonly formaldehyde or glucose).

Eight protocols were tested, covering both traditional silver nitrate (AgNO₃) methods and newer silver‑diammine (