INTRODUCTIONColloidal Gold is the most sensitive staining technique for proteins bound on membranes, detecting as little as 1-3 ng of protein. Protein spots are permanently stained a dark red after incubation with the Colloidal Gold solution. Colloidal Gold staining can detect proteins on both nitrocellulose and PVDF membranes, but it is not recommended for nylon membranes.