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August 14, 2006

Modified nanoscale transistor could dramatically speed up the detection of DNA sequences

The detector consists of a quantum dot with a piece of DNA attached. It only allows current to flow when a matching sequence of DNA binds to the attached piece and could provide a simple, faster way to detect viruses or to track gene expression.

Researchers at Quantum Logic Devices, in Texas, US, constructed the detector by modifying an existing transistor design. This features a 5-nanometre-wide gold particle flanked by three electrodes.

Currently label DNA molecules using fluorescence, but that can take around 24 hours to produce a result. The new detector can detect a piece of DNA in less than 30 minutes. The detector would be ideal for diagnosing viruses quickly.

It can detect a single matching sequence. Sample purity becomes important, if you've got one bit of crud in there it could interfere.

The team at Quantum Logic Devices are currently developing a chip containing thousands of individual quantum dot transistors, manufactured using conventional semiconductor technologies. These could keep track of levels of combinations of genes in a biological sample

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