Metal particles can nucleate the highly specific deposition of silver from an appropriate silver salt solution in the presence of a suitable reducing agent. The silver coated gold particle then catalyzes more silver deposition and the silver grains grow in size.
In this way even small gold particles such as Nanogold® may be enlarged up to 30 to 100 nm in size, resulting in greatly enhanced visibility by electron microscopy, dark staining in the light microscope and the ultrasensitive visualization of antigens on blots and in gels.
Nanoprobes offers two silver enhancers with complementary properties: HQ Silver and LI Silver.
Features of Nanoprobes Silver Enhancers
HQ Silver
Unique formulation for the best possible results with Nanogold® in critical applications, particularly in the electron microscope. Slightly light sensitive: should be used in indirect light or with a SafeLight (For a comparison with other silver enhancers, see: Humbel, B. M., et al.: J. Histochem. Cytochem., 43, 735-737 (1995). For uses, see: Baude, A., et al.: Neuroscience, 69, 1031-1055 (1997)).
Neutral pH for excellent preservation of structural integrity.
Protective thickening agent for the most uniform, reproducible particle size distribution.
In electron microscopy the 1.4 nm Nanogold® develops to round grains that are more variable in size when < 20 nm. The development then slows, and the smaller grains "catch up." At 80 nm, all silver grains from the 1.4 nm Nanogold® are quite uniform. With HQ Silver, this occurs after about a 3 minute development period, or with LI Silver after ^7 minutes. In the light microscope, superior penetration, low backgrounds, and ultrasensitive staining may be realized with Nanogold® reagents and LI Silver.
Immunogold with silver enhancement provides simple, robust and permanent record assays with super sensitivity. Nanogold® can be grown in a reasonably controlled and uniform manner to produce particles ^2 to >100 nm in size with silver development times of ^30 seconds to ^30 minutes. The smaller sizes are excellent for EM work whereas the intermediate sizes are useful for light and confocal microscopy. The largest sizes provide ultrasensitive visualization with the naked eye and are useful in immunoblots, gels and Westerns.
Immunoblot with Nanogold®
and LI Silver Enhancement
Nanogold®-anti-mouse Fab' blotted against mouse IgG, developed with LI Silver (Nanoprobes). These ultra small gold particles nucleate silver deposition so well that unprecedented sensitivity is achieved. This immunodot blot shows 0.1 pg sensitivity (arrow).
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