The preparation of protein A-gold complexes with 3 nm and 15nm gold particles and their use in labelling multiple antigens on ultra-thin sections.

The preparation of a protein A-gold complex (pAg3) using 3 nm gold particles and its application for labelling of intracellular antigens on thin sections is reported. The 3 nm gold particle is the smallest metal particle currently available for cytochemistry and permits a higher resolution of the pAg technique. Furthermore, it can be used in double labelling experiments in conjunction with a pAg complex prepared from 15nm gold particles. For double labelling, the pAg3 complex must be used for staining of the first antigen since otherwise a non-specific co-labelling of the two pAg complexes results.