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.

Because of its bactericidal properties it was used to treat gonorrhea before the discovery of antibiotics. Designer of first silver protein formulation was Arthur Eichengrün, German chemist working for Bayer. It was introduced for therapeutic use in 1897.