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.
Hundreds of ciliate species have been discovered using Protargol staining.
[2] 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.