Silver staining

Source: Wikipedia, the free encyclopedia.

In

polyacrylamide gels
.

In traditional stained glass, silver stain is a technique to produce yellow to orange or brown shades (or green on a blue glass base), by adding a mixture containing silver compounds (notably silver nitrate), and firing lightly. It was introduced soon after 1800, and is the "stain" in the term "stained glass". Silver compounds[1] are mixed with binding substances, applied to the surface of glass, and then fired in a furnace or kiln.[2][3][4]

History

Camillo Golgi perfected silver staining for the study of the nervous system. Although the exact chemical mechanism by which this occurs is unknown,[5] Golgi's method stains a limited number of cells at random in their entirety.[6]

Silver staining was introduced by Kerenyi and Gallyas as a sensitive procedure to detect trace amounts of proteins in

macromolecules that have been separated in a variety of supports.[8]

Classical Coomassie brilliant blue staining can usually detect a 50 ng protein band; silver staining increases the sensitivity typically 50 times.

Many variables can influence the color intensity and every protein has its own staining characteristics; clean glassware, pure reagents, and water of highest purity are the key points to successful staining.[9]

Chemistry

Some cells are argentaffin. These

formalin fixation. Other cells are argyrophilic. These reduce silver solution to metallic silver after being exposed to the stain that contains a reductant, for example hydroquinone
or formalin.

Von Kossa Stain. When subjected to a reducing agent, usually hydroquinone, it forms black elementary silver. This is used for study of formation of calcium phosphate
particles during bone growth.

Applications

Histological characterisation

Silver staining aids the visualization of targets of interest, namely intracellular and extracellular cellular components such as

reticulin fibres by the deposition of metallic silver particles on the targets of interest.[10]

Diagnostic microbiology

Pneumocystis, Cryptococcus, and Candida are organisms that are stained with silver.[citation needed
]

Karyotype analysis

Silver staining is used in

nucleolar organization region (NOR)-associated protein, producing a dark region wherein the silver is deposited and denoting the activity of rRNA genes within the NOR. Human chromosomes 13, 14, 15, 21, and 22 have NORs, which increase the silver stain activity by at least 50 times.[citation needed
]

Genomic and proteomic analysis

Silver staining is used to stain gels. The silver stain of proteins in

polyacrylamide gels used in SDS-PAGE,[13][14][15][16][17] and also for staining DNA or RNA.[18] The glycosylations of glycoproteins and polysaccharides can be oxidised by a 1-hour pre-treatment with 0.1% periodic acid at 4 °C, which improves the binding of silver ions and the staining result.[19]

First, the proteins are denatured in the gel by a fixative solution of 10% acetic acid and 30% ethanol and precipitated, at the same time the detergent (mostly SDS) is extracted. The diffusion of the proteins is thus significantly reduced. After repeated washing with water, the gel is incubated in a silver nitrate solution. Silver ions bind to negatively charged side chains of the proteins. Excess silver ions are then washed off with water. In the final development step, the silver ions are reduced to elemental silver by addition of alkaline formaldehyde. This stains the sites where proteins are present, brown to black.

The intensity of the staining depends on the

reagents influence the silver stain.[20] Common artifacts in silver stained gels are bands of keratin in the ranges of 54–57 kDa and 65–68 kDa[21]
as a contamination of the sample prior to the electrophoresis.

Methenamine silver stains

There are several silver stains incorporating methenamine, including:

References

  1. ^ Steinhoff, Frederick Louis (1973). Ceramic Industry. Industrial Publications, Incorporated.
  2. ^ Chambers's encyclopaedia. Pergamon Press. 1967.
  3. ^ "Facts about Glass: Silver Stain". Boppard Conservation Project – Glasgow Museums. 18 July 2013.
  4. ISBN 978-0754645573
    .
  5. ^ Golgi C (1873). "Sulla struttura della sostanza grigia del cervello". Gazzetta Medica Italiana (Lombardia). 33: 244–246.
  6. S2CID 24331507
    .
  7. PMID 4744834
    .
  8. PMID 94518.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
    )
  9. ^ Hempelmann E, Schulze M, Götze O (1984). "Free SH-groups are important for the polychromatic staining of proteins with silver nitrate". Neuhof V (Ed)Electrophoresis '84, Verlag Chemie Weinheim 1984: 328–330.
  10. PMID 15210137
    .
  11. PMID 15287874
    .
  12. PMID 4744834
    .
  13. PMID 92027
    .
  14. PMID 94518{{citation}}: CS1 maint: multiple names: authors list (link
    )
  15. S2CID 33007991
    .
  16. S2CID 43084621
    .
  17. S2CID 52820065
    .
  18. S2CID 84471792
    .
  19. PMID 6176144
    .
  20. ^ E. Hempelmann, M. Schulze, O. Götze: Free SH-groups are important for the polychromatic staining of proteins with silver nitrate. In: V. Neuhof (Editor): Electrophoresis. Verlag Chemie, Weinheim, 1984, pp. 328–330.
  21. PMID 6197906
    .
  22. ^ Hempelmann E, Götze O (1984). "Characterization of membrane proteins by polychromatic silver staining". Hoppe-Seyler's Z Physiol Chem. 365: 241–242.
  • MedEd at Loyola Histo/practical/stains/hp2-55.html
  • [1] Hempelmann E. SDS-Protein PAGE and protein detection by silverstaining and immunoblotting of Plasmodium falciparum proteins. in: Moll K, Ljungström J, Perlmann H, Scherf A, Wahlgren M (eds) Methods in Malaria Research, 5th edition, 2008, 263-266
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