Colloidal gold silver enhancement

Immunochromatography, colloidal gold, silver enhancement 10 minutes Evanescent wave fiber-optic immunosensor Colorimetric and chemiluminescence ELISA Immunochromatography, colloidal gold, silver enhancement 10 minutes Sandwich hybrid receptor-immunoassay,... 

Furthermore, the dense, saturation packing of R6G or other dye molecules on colloidal gold/silver surface does not limit Raman intensities in the way that fluorescence intensities are lowered by excited state dipole-dipole interactions. In comparison with flnorescent dyes and quantum dots, the enhanced Raman probes have an intrinsic amplification mechanism, with improved encoding and mnltiplexing capabilities. If multiple (4 or even more) sizes of gold/silver nanoparticles in the 50-300 nm diameter range with a narrow size distribution can be prepared, and then loaded with 20 different dye molecules with unique SERS fingerprints, this would provide 80 probes for each metal nanoparticle. 

J. Wang, R. Polsky, and X. Danke, Silver-enhanced colloidal gold electrochemical stripping detection of DNA hybridization. Langmuir 17, 5739-5741 (2001). 

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... 

Fig. 1. Small intestine formaldehyde-fixed, paraffin-embedded. Section was stained with Concanavilin A conjngated to 5-nm colloidal gold. The gold was then silver-enhanced. Staining of mucous on the cell snrface and in goblet cells is seen.

Scopsi, L. (1989) Silver-enhanced colloidal gold method, in Colloidal Gold, vol. 1 (Hayat, M. A., ed.), Academic, New York, pp. 251-295. 

Bienz, K, Egger, D, and Pasamontes, L (1986) Electron microscopic lmmuno-cytochemistry. silver enhancement of colloidal gold marker allows double labeling with the same primary antibody J Histochem Cytochem 34,1337-1342. 

The sensitivity of the detection is usually improved by the silver enhancement method. A better detection limit was reported when a silver enhancement method was employed, based on the precipitation of silver on AuNPs tags and its dissolution (in HNO3) and subsequent electrochemical potentiometric stripping detection [43]. The new silver-enhanced colloidal gold stripping detection strategy represented an attractive alternative to indirect optical affinity assays of nucleic acids and other biomolecules. 

Uriel, J., Lorenzo, H. K., Macho, A., de Feijter, A. W., and Mishal, Z. (1995) Visualization of silver-enhanced reaction products from protein and immuno-colloidal gold probes by laser scanning confocal microscopy in reflection mode. Histochem. Cell. Biol. 103,355-361. 

Figure 10.2. Electron micrographs of typical colloidal gold and silver particle structures used in SERS experiments. (a) Colloidal gold particles in the isolated and aggregated stage after addition of NaCl. (b) Typical colloidal silver clusters exhibiting strong SERS enhancement. (With permission from Refs. 17 and 18.)...

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