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Technology
Diffinity Genomics technology is based on a discovery that, under certain conditions, single and double-stranded DNA have different affinities for adsorption on gold nanoparticles in a colloidal suspension.
Single-stranded and double-stranded DNA have different characteristic charge distributions and therefore interact differently with ions on gold nanoparticles. This discovery is exploited in the design of genetic assays to determine if a fluorescently-tagged probe strand of ss-DNA matches a sequence in a target analyte. When it does not, the fluorescently-tagged probe adsorbs on a gold nanoparticle and its fluorescence is quenched. If the probe sequence is able to hybridize to the target, it will not adsorb on the gold nanoparticle and its fluorescence persists. Schematically, the assay protocol is described in this figure:
Additional information about the technology and applications in genetic testing can be found in these publications:
- Li, H., and Rothberg, L. (2004) Colorimetric detection of DNA sequences based on electrostatic interactions with unmodified gold nanoparticles. Proc Natl Acad Sci U S A. 101(39):14036-9.
- Li, H., and Rothberg, L.J. (2004) DNA sequence detection using selective fluorescence quenching of tagged oligonucleotide probes by gold nanoparticles. Anal Chem 76(18):5414-7.
- Li H, Rothberg LJ. (2004) Label-free colorimetric detection of specific sequences in genomic DNA amplified by the polymerase chain reaction. J Am Chem Soc. 2004 Sep 8;126(35):10958-61.
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