SPI-Mark™ Colloidal Gold Reagents
Quality At An Unbeatable Price!
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Sharp size distribution of SPI-Mark™ Colloidal Gold products
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Products:
Gold Conjugates
- Electron microscopy
- Light microscopy
Unconjugated Gold Probes
- Light, electron and other types of microscopy including materials science applications
The SPI Mark Colloidal gold probes have been offered for a number of years
for research applications in electron and light microscopy. But with the
passing of time, researchers and ordinary end users have developed new and
exciting other applications such as point of care rapid diagnostic lateral
flow testing systems (e.g. "clinical" or "bioassay" applications). A
rapidly growing application is for use with microarray technology for the
reading and analysis of test results. These are very definitely not the
same suspension with the same material but with a different label!
There have been differences formulated into them that are specific for the
particular application any effort to cross-use these different products and
applications can surely lead to an uncertain result.
Silver applications:
An altogether new application is in the forensic science area using silver
colloids for Raman surface spectroscopy forgery detection in printed
documents.
An important note about product selection:
Great caution should be used before deciding to select a gold products for an
application other than the intended use. We know that the tendency could be
great to use, for example, a light microscopy quality gold for TEM. It may
be the same antibody and the same colloid size but as you will find,
sharpness of the size distribution (size specification and the coefficient
of variation) will be unacceptable for use in the TEM application. Just
how are they different? The Research Grade conjugates, "of the type offered by SPI Supplies", both electron as
well as light microscopy contain glycerol in the buffer which enables them
to be frozen so they can be thawed out at a later date and used beyond the
label-stated expiration date (but under no circumstances will SPI Supplies
honor the guarantee beyond the original expiration date. In contrast,
those conjugates for "clinical" or "bioassay" applications, contain no
glycerin in the buffer and therefore can not be frozen. The concept of
"expiration date" is so much in the eyes of the beholder, that is, while the
product might not be effective beyond a certain date for one application,
there might be a long list of other applications for which the product might
very well still be adequate. Therefore it is really up to the end user
customer to decide whether a particular product could or could not be used.
There is a tendency to use research grade products, such as the products for
light and electron microscopy, for what are really clinical applications
(point of care rapid diagnostic lateral flow testing systems". Again, at
first glance, these look like the same products but they are not.
Main application areas for SPI-Mark colloidal gold problems.
Our flagship products: EM grade colloidal gold probes and conjugates
Gold labels are the most satisfactory method of labeling antigens for visualization in the
electron microscope. Since their introduction in the early 1970's,
there has been major growth in the number of applications
in animal and plant biology as well as microbiology.
The main advantages and features of gold labeling lie in the high contrast and unequivocal
nature of the label, the range of particle sizes suitable for different magnifications,
the extreme sensitivity, and the stability of the signal. Be sure you have at least
some understanding of
these advantages and features before embarking on studies involving
immunogold labeling or other applications for these products. Equally important is the
choice of particle size.
Which gold conjugate should I be using?
The appropriate gold conjugate may be selected according to the criteria described in our
How to Choose a Gold Conjugate section.
What protocol should I be using?
Over the years, a
large number of different protocols have been devised for carrying out immunogold staining of tissue samples.
Point of Care Lateral Flow Applications (BioAssay)
Microarray technology
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Saturday March 13, 2010
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