Colloidal gold electron microscopy

Figure 6 Detail of the interface space (IN) between the fungal wall (U) of Glomuf versiforvte and the host membrane of leek (PL), as seen by electron microscopy. Xylo-glucan molecules are revealed by using a specific antibody and colloidal gold granules. P, host cell F, fungus, X 30,000.

A review of preparative methods for metal sols (colloidal metal particles) suspended in solution is given. The problems involved with the preparation and stabilization of non-aqueous metal colloidal particles are noted. A new method is described for preparing non-aqueous metal sols based on the clustering of solvated metal atoms (from metal vaporization) in cold organic solvents. Gold-acetone colloidal solutions are discussed in detail, especially their preparation, control of particle size (2-9 nm), electrophoresis measurements, electron microscopy, GC-MS, resistivity, and related studies. Particle stabilization involves both electrostatic and steric mechanisms and these are discussed in comparison with aqueous systems. 

Honisbenger, M., and Rosset, J. (1977) Colloidal gold, a useful marker for transmission and scanning electron microscopy./. Histochem. Cytochem. 25, 295. 

Labeling antibodies with colloidal gold was developed for electron microscopy, but the procedure can be used for light microscopy as well. 

Romano EL, Stolinski C, Hughes-Jones NC. An antiglobulin reagent labeled with colloidal gold for use in electron microscopy. Immunochemistry 1974 11 521-522. 

Romano EL, Romano M. Staphyloccal protein A bound to colloidal gold a useful reagent to label antigen-antibody sites for electron microscopy. Immunochemistry 1977 14 711-715. 

Tanaka K, Mitsushima A, Yamagata N, Kashima Y, Takayama H. Direct visualization of colloidal gold-bound molecules and a cell surface receptor by ultrahigh resolution scanning electron microscopy. J Microsc 1990 161 455—461. 

Yamaguchi M, Kondo I. Immunoelectron microscopy of Proteus vulgaris by the plasma polymerization metal-extraction replica method differential staining of flagellar (H) and somatic (0) antigens by colloidal golds. J Electron Microsc 1989 38 382-388. 

Immunohistochemical labeling for electron microscopy is based on the same principles as immunohistochemistry for light microscopy. The differences are that specimen sections must be much thinner (50 100 nm) and the label must be electron-dense. The first electron-dense labels used for immunolabeling at the electron microscope level were ferritin and peroxidase. Peroxidase label can be visualized using DAB reaction product which becomes electron-dense after osmi-cation. With the advent of colloidal gold particles as markers in immunocytochemical... 

Colloidal gold. This is a useful label for both direct and indirect staining methods since it requires no further reagent additions. Gold probes may be readily seen by light microscopy when coupled with silver enhancement and in addition, being electron dense, offer excellent sensitivity for the electron microscope. 

Other labels that have particular uses for electron microscopy are ferritin (11) and colloidal gold particles (12,13) (see Chapters 40-45). Gold particles are available in different sizes, therefore allowing simultaneous detection of several components on the same sample. Colloidal gold may also be detected with the light microscope following silver enhancement (see Chapter 29). In addition, radioactive labels have found some use in both light and electron... 

Geoghegan, W. D., Scillian, J. J., and Ackerman, G. A. (1978) The detection of human B lymphocytes by both light and electron microscopy utilizing colloidal gold labeled anti-immunoglobulin. Immunol. Commun. 7, 1-12. 

Bashong, W., Lucocq, J. M., and Roth, J. (1985) Thiocyanate-Gold small (2-3 nm) colloidal gold for affinity cytochemical labeling in electron microscopy. Histochem. 83,409 11. 

Bendayan, M. (1989) Protein A-gold and protein G-gold postembedding immuno-electron microscopy, in Colloidal Gold, vol. 1 (Hayat, M. A., ed.). Academic, New York, pp. 34-96. 

Horisberger, M. (1981) Colloidal gold a cytochemical marker for hght and fluorescent microscopy and for transmission and scanning electron microscopy, in Scanning Electron Microscopy II (Johari, O., ed.), SEM, Inc., AMF O Hare, Chicago, pp. 9-31. 

Protein-labeled colloidal gold probes suit as well as for immuno-histochemistry in electron microscopy as for detection of antigens or glycoproteins on blots. There are several protocols for enhancement of electron density and visible color resulting in higher sensitivity. 

Electron microscopy permits the detailed study of cell relationships within tissues and organelles within cells. Two ultrastructural techniques in which gold probes have proven invaluable are mununocytochemistry and in situ hybridization, and these will be described here. Until 1980, peroxidase was the marker of choice, but now colloidal gold is almost universally used. The advantages of colloidal gold are that ... 

Hodges, G M., Southgate, J, and Toulson, E. C (1987) Colloidal gold-a powerful tool in S E. M. immunocytochemistry an overview of bioapplications. Scanning Electron Microscopy 1, 301—318. 

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