Gold labeling techniques, antigen

One particularly novel carrier was reported to consist of 50-70 nm colloidal gold particles of the type often used in cytochemical labeling techniques for microscopy (Pow and Crook, 1993) (Chapter 24). Adsorption of peptide antigens onto gold and subsequent injection of the complex into rabbits in an adjuvant mixture resulted in rapid production of antibody of extremely high titer. The resultant antibodies could be used in immunocytochemistry at dilutions from l-in-250,000 down to l-in-1,000,000, which is orders-of-magnitude beyond the dilutions typically used with lower-titer antibodies. 

Gold labeling may be used in the recently introduced catalyzed reporter deposition-immunogold technique where biotinylated tyramide molecules are attached the antibody-antigen complex site the biotinylated sites are visualized by interaction with streptavidin-gold (46,47). 

Immunofluorescence has become one of the most important tools of contemporary cell biological research, particularly for localising specific antigenic determinants such as newly expressed proteins in the cell. In this context, double immunofluorescence techniques are very powerful use of two antibodies labelled with distinguishable fluorophores allows different cell structural elements to be visualised simultaneously. A similar approach can be used in electron microscopy by labelling different proteins with gold particles of different sizes. 

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