For many applications, silver salt-based autometallography (often also called silver enhancement or silver development)5,8 is required to visualize colloidal gold (1-5 nm in diameter) or the small 1.4 nm Nanogold® particles (Nanoprobes, Yaphank, NY, USA).11 Although even Nanogold may be seen directly by scanning-transmission electron microscopy (STEM), by transmission EM (TEM; in thin sections without stain or ice-embedded cryo-EM samples), energy filtered TEM, and scanning EM (SEM), silver enhancement makes viewing in the EM more facile since the particles are enlarged to approximately 10 to 20 nm, convenient for most specimens. Autometallographic (AMG) enhancement is required in order to visualize smaller gold particles such as Nanogold for light microscopy (LM) or in blots or gels. This chapter includes the following protocols:

• Protocol for HQ silver enhancement of Nanogold.