Silver Staining- Principle, Procedure, Applications


Silver staining is a special yet powerful staining technique that is used for the detection and identification of proteins in gels. This is because silver binds to the chemical terminal or side chains of amino groups i.e carboxyl and sulfhydryl groups . It has been used for decades now to separate proteins from polyacrylamide gel electrophoresis (PAGE) . The nucleation sites where there are tiny crevices where the free gas-liquid surface is maintained in proteins, promote formaldehyde reduction of silver ions into microscopic silver crystals which facilitate their detection .

The protein detection by silver staining is a highly sensitive method yet specific and selective for proteins. It produces an image with reduced background and less mass spectrometry interference . The general procedure for silver staining includes the fixation of silver, sensitization, impregnation of silver, and development of an image. Several variants of the technique have emerged, some performed within an hour and others taking over 24 hours to complete . However, the end stain can remain stable for several weeks before it loses effectiveness for observation .

Silver staining can detect proteins in the low nanogram range, making it more sensitive than other colorimetric methods such as Coomassie blue staining . It can also be used to stain DNA or RNA molecules in gels . Silver staining is compatible with downstream processing, such as mass spectrometry analysis after protein digestion . It requires simple and cheap equipment and chemicals, and can be performed using a microwave oven for faster results .

Silver staining is a useful technique for protein identification in gels as it combines excellent sensitivity, specificity, simplicity, cost-effectiveness, reliability, and versatility. It can be applied to various types of gels, such as SDS-PAGE, native PAGE, 2D-PAGE, agarose gels, etc. It can also be used to visualize protein bands that are difficult to detect by other methods, such as low-abundance proteins, post-translational modifications, or protein-protein interactions .