Updated: August 3, 2001
N A N O P R O B E S E - N E W S
Vol. 2, No. 7 August 3, 2001
This monthly newsletter is keep you informed about techniques to improve your immunogold labeling, highlight interesting articles and novel metal nanoparticle applications, and answer your questions. We hope you enjoy it and find it useful.
Have questions, or issues you would like to see addressed in the next
issue? Let us know by e-mailing tech@nanoprobes.com.
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Jim Hainfeld of Nanoprobes will be presenting a talk on the patterned deposition of Nanogold onto DNA as a means of fabricating nanowires. This talk will be part of the symposium on Labeling for Microscopy and Correlative Microscopy on Tuesday, August 6 in Room 202A, and will be presented at 11:00 am. Also in this symposium will be presentations by John Robinson of Ohio State University, who has published many articles on the applications of Nanogold and FluoroNanogold (at 9:30 am), and in the Tuesday afternoon poster session on the same topic, G. Grondin and A. R. Beaudoin describe a new pre-embedding immunogold procedure permitting a very high signal with a very good ultrastructure.
Microscopy & Microanalysis 2001:
http://www.microscopy.com/MSAMeetings/MMMeeting.html
Search engine for abstract titles:
http://www.msa.microscopy.com/cgi-bin/M&M01Program.pl
See abstracts presented by Nanoprobes scientists at past Microscopy and Microanalysis meetings on our Applications pages:
www.nanoprobes.com/Applic.html
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You can combine Nanogold labeling and silver or gold enhancement with other labeling methods, such as enzymatic labeling, in the same specimen, and readily distinguish the two different types of signal. In these three papers, the investigators used Nanogold with silver enhancement to mark one site of interest, and then used peroxidase/DAB labeling to label a second site:
- Bernard, V.; Levey, A. I., and Bloch, B.: J. Neurosci., 19, 10237-10249 (1999).
Abstract: http://www.jneurosci.org/cgi/content/abstract/19/23/10249
- Li, H.; Ohishi, H.; Kinoshita, A.; Shigemoto, R.; Nomura, S., and Mizuno, N.: Neuroscience lett., 223, 153-156 (1997).
Abstract: http://www.jhc.org/cgi/content/abstract/47/10/1275
- Salas, P. J. I.: J. Cell Biol., 146, 645-657 (1999).
Abstract: http://www.jcb.org/cgi/content/abstract/146/3/645
Visit the references section of our web site to see some of the other applications of silver and gold enhancement. Like all our reference pages, the one for silver and gold enhancement is available sorted by product, or by application:
www.nanoprobes.com/RefTopSE.html (sorted by application).
www.nanoprobes.com/Refsilver.html (sorted by product).
If you decide to try this procedure, we recommend completing the Nanogold labeling and silver or gold enhancement before the peroxidase/DAB labeling. This is because the reagents used with DAB/peroxidase staining can nucleate silver or gold deposition during enhancement; if you conduct this procedure before gold labeling and silver or gold enhancement, you may find non-specific background staining with the silver or gold enhancement.
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Because Nanogold is relatively small, you can make it difficult to visualize by applying heavy metal based stains such as uranyl acetate or lead citrate. However, if you are negative staining - staining the regions between or around the edges of your specimens - you have the option of using a lighter stain. NanoVan is based on vanadium, and therefore gives a highly uniform but much less electron-dense staining against which the Nanogold particles are easily visualized. Furthermore, by mixing with our tungsten-based negative stain, Nano-W, you can "tune" the opacity to suit your application. For an example of NanoVan in use, see Gregori, L., et al.; J. Biol. Chem., 272, 58-62 (1997).
Reprint (pdf): http://www.jbc.org/cgi/reprint/272/1/58.pdf
Other references: www.nanoprobes.com/Refstain.html
Our paper from M & M 94: www.nanoprobes.com/MSANV.html
Catalog Info and details: www.nanoprobes.com/Nstain.html
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If you'd like to avoid problems with your samples charging under the electron beam, consider conductive polymer substrates, prepared with 3-octadecylpyrrole and 3-octadecanoylpyrrole. These are used with ferric chloride as a catalyst and a trace of pyrrole vapor to form thin layers of conductive polypyrroles in a Langmuir-Blodgett trough or similar apparatus, which can then be transferred to EM specimens.
For more details, see our paper: www.nanoprobes.com/Conduct.html
Catalog information: conductive polymers: www.nanoprobes.com/Polyms.html
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Alexandre and co-workers report the use of Nanogold-streptavidin with silver enhancement as a potential low-cost colorimetric detection method for biochips. The authors compared the sensitivities of the Nanogold-silver colorimetric method with the Cy-3 fluorescence method, and found that the detection limit of both methods was equivalent and corresponds to 1 amol of biotinylated DNA attached on an array. Reference:
Alexandre, I.; Hamels, S.; Dufour, S.; Collet, J.; Zammatteo, N.; De Longueville, F.; Gala, J. L., and Remacle, J. Colorimetric silver detection of dna microarrays. Anal. Biochem., 295, 1-8 (2001).
Abstract: http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11476538&dopt=Abstract
Parodi and co-workers describe the use of DPPE-Nanogold for assembling gold nanoparticle patterns for molecular electronics applications; DPPE-Nanogold was mixed with cadmium arachidates and alkanes, and deposited onto substrates. SEM and atomic force microscopy analysis showed that it was possible to generate phase-separated regions of DPPE-Nanogold and organic molecules. Reference:
Parodi, M. T.; Ricci, D.; Rocchia, W.; Sbrana, F., and Di Zitti, E.: Assembling gold nanoparticle patterns for molecular electronics applications. Sens. Microsyst., Proc. Ital. Conf., 5th, 66-70 (2000).
The use of a Nanogold-hyaluronic acid derivative, and other hyaluronic acid-based fluorescent and reporter group probes, is reported by Prestwich and co-workers. Hyaluronic acid is important as a potential carrier for controlled-release pharmaceuticals, as well as a biocompatible coating agent for polymeric and metal medical devices. Reference:
Prestwich, G. D.; Luo, Y.; Ziebell, M. R.; Vercruysse, K. P.; Kirker, S. R.; Kelly, R., and MacMaster, John S.; Int. Congr. Ser., 1196 (New Frontiers in Medical Sciences: Redefining Hyaluronan), 181-194 (2000).
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