Preparation of Colloidal Gold Probes

As long ago as 1857 (1 ), Michael Faraday in an address to the Royal Society recognized the reactive properties of colloidal metal particles (in particular gold) with light. Since 1933 (2 ), a range of methods have been devised for producing gold sols. It was not until 1971, however, that Faulk and Taylor (3 ) published a method for binding proteins to gold particles for use in lmmunocytochemistry at the electron microscope level. Nowadays, colloidal gold is incorporated into probes that are widely used in the biological sciences both for light and electron microscopy.