Silver enhancement has long been used by microscopists to better visualize gold labeling, especially when using small gold particles. Silver is specifically deposited around the gold particle, growing it in size.
For TEM, the 1.4 nm Nanogold® can be enlarged to 10-20 nm for clear visiblility, even at low magnifications. Using an initial small gold immunoprobe allows better penetration into tissues (up to 40 microns!) and better labeling of antigens. Then silver enhancement makes everything clearly visible.
The development time can be extended to deposit more silver and make the signal visible by bright field (or reflection) light microscopy. With a little more development time, the signal can be seen by the naked eye, and can be used with dot blots or Westerns.
Nanoprobes has now extended this technology by introducing a GOLD developer, GoldEnhance™. It works similarly to silver enhancement, but deposits gold around the initial gold particle instead of silver.
Why GOLD?
There are a number of advantages:
may safely be used before osmium tetroxide staining (silver is dissolved by the oxidizing agent O4; gold is stable)
lower backgrounds than silver in some cases; autonucleation minimal even after 1-2 hours
for SEM, gold gives a much better backscatter signal than silver
compatible with physiological buffers (silver precipitates with chloride ion, as in PBS buffer; gold does not)
reaction is less pH senstitive than silver, and GoldEnhance™ is near neutral for best structural preservation of biological samples (many silver enhancers have a pH of 3-4)
excellent shelf life
low viscosity for easy and accurate mixing of components
Several labs have obtained superb results, which improve on those obtained with silver enhancement both at the light and electron microscope level.
How it works.
Features and Applications of GoldEnhance™ EM
GoldEnhance™ EM is specially formulated for the best results in electron microscopy. Using GoldEnhance™ EM, you can expect these advantages:
Higher density of enlarged particles for clearer imaging.
Resistant to osmium tetroxide etching: may safely be used before osmium tetroxide staining with no need for gold toning or other protective treatments (silver is dissolved by the oxidizing agent OsO4; gold is stable).
for SEM, gold gives a much better backscatter signal than silver.
Light micrographs of formalin-fixed serial sections of cervical carcinoma, in situ hybridized for HPV-16/18 using a biotinylated probe (Pathogene-HPV kit, Enzo) (bar=10 micrometers).
(1) direct detection using streptavidin-peroxidase-DAB
(2) Direct detection using Nanogold®-streptavidin followed by development with GOLDENHANCE
(Micrographs courtesy of Prof. G. W. Hacker. Medical Research Coordination Center, University of Salzburg, Austria)
Paying by Purchase Order? Please use our Online Order Form. Custom conjugation is also available, of Nanogold®, FluoroNanogold, undecagold
or colloidal gold to primary antibodies, peptides, small molecules, or other molecules.
Features and Applications of GoldEnhance™ EMInstructions (PDF)
