silver proteinate

Silver proteinate (brand name: Protargol) is used in electron microscopy with periodic acid and thiocarbohydrazide or thiosemicarbohydrazide as a positive stain for carbohydrates such as glycogen. It can also be used for light microscopy to stain nerve tissue. It is normally available as 8% silver in combination with albumin.[http://www.sigmaaldrich.com/catalog/product/fluka/05495?lang=en®ion=GB Silver proteinate] at Sigma-Aldrich

Staining ciliates with silver proteinate can reveal the infraciliature, an important character for identification of ciliates. Hundreds of ciliate species have been discovered using Protargol staining.{{cite journal | doi=10.1111/jeu.12515 | title=An Optimized Protocol of Protargol Staining for Ciliated Protozoa | year=2018 | last1=Ji | first1=Daode | last2=Wang | first2=Yunfeng | journal=Journal of Eukaryotic Microbiology | volume=65 | issue=5 | pages=705–708 | pmid=29532600 | s2cid=3839382 }}

Because of its bactericidal properties it was used to treat gonorrhea before the discovery of antibiotics. The inventor of the first silver protein formulation was Arthur Eichengrün, a German chemist working for Bayer. It was introduced for therapeutic use in 1897.Vaupel, E. (2005), Arthur Eichengrün—Tribute to a Forgotten Chemist, Entrepreneur, and German Jew Angew. Chem. Int. Ed., 44: 3344–3355. doi: 10.1002/anie.200462959State Medical Examining and Licensing Boards [http://chestofbooks.com/health/materia-medica-drugs/American-Medical-Association/A-Handbook-of-Useful-Drugs/Protargol-Protargol-N-N-R-Silver-Proteinate.html A Handbook of Useful Drugs: Protargol] 1913 Press Of The American Medical Association (hosted on: chestofbooks.com)