{{No footnotes, date=October 2017 Silverquant is a labeling and detection method for

DNA microarrays A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to ...

or protein microarrays. A synonym is detection. In contrast to the classical signal detection on microarrays by using

fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

, the colorimetric detection is more sensitive and ozone-stable.

Chemical reaction

The probe to be detected is labeled with some

biotin Biotin (or vitamin B7) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name ''biotin'', bor ...

-molecules. After incubation with a gold-coupled anti-biotin conjugate,

silver nitrate Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic' ...

and a reducing agent are added. The reaction starts whereas the gold particle serves as a starting point for the silver precipitation. The reaction needs to be stopped after a specific time. The constant reaction time is essential to obtain comparable results.

Detection

The silver-stained spots on the microarray are clearly visible. By using a transmission microarray scanner, the signals are transformed into digital values which are finally available as an image file.

References

Alexandre I et al. Anal Biochem. 2001 Aug 1;295(1):1-8. Gene expression Bioinformatics DNA Microarrays