Digital DNA detector spots single molecules
I am posting this because of the idea that some people have that perps are able to isolate a TI in a crowd of people by detecting their DNA signatures.
Susan
http://www.newscientisttech.com/article.ns?id=dn9744&feedId=tech_rss20
A modified nanoscale transistor could dramatically speed up the detection of DNA sequences, according to US researchers. 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. One of the electrodes switches the transistor on and off while the other two connect it to a larger circuit. The researchers simply removed the controlling electrode and attached a 36-letters-long sequence of DNA to the particle instead. Attaching the DNA molecule means that the device now switches on and off when a matching sequence of DNA becomes attached. Digital signal "The bonds that form between the two strands shift charge around a little and corresponding charge is induced in the quantum dot," explains Louis Brousseau, CEO of Quantum Logic Devices and lead researcher on the project. This switches the current on and off to create a "digital signal," he adds. Brousseau believes the technique could accelerate medical research and the detection of dangerous pathogens. "Researchers currently label DNA molecules using fluorescence, but that can take around 24 hours to produce a result," he says. The new detector can detect a piece of DNA in less than 30 minutes. "The many variables of current procedures make interpretation more art than science," Brousseau adds. "This way produces much more clear-cut results." He thinks the detector would be ideal for diagnosing viruses quickly. "They can replicate very fast so you want to know if someone is infected quickly," he says. "Waiting 24 hours can miss the critical period." Cruddy interference Sub Reddy, a biosensor expert at Surrey University in the UK, says the detectors should be extremely sensitive. "It can detect a single matching sequence, while current methods record the aggregate of many such events," he notes. "It's usually necessary to amplify the DNA in a sample to get a signal, but you could cut that out and perhaps use it in on samples in the field." However, Reddy also sees some drawbacks. "Sample purity becomes important, if you've got one bit of crud in there it could interfere," he warns. 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, Brousseau says.
Susan
http://www.newscientisttech.com/article.ns?id=dn9744&feedId=tech_rss20
A modified nanoscale transistor could dramatically speed up the detection of DNA sequences, according to US researchers. 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. One of the electrodes switches the transistor on and off while the other two connect it to a larger circuit. The researchers simply removed the controlling electrode and attached a 36-letters-long sequence of DNA to the particle instead. Attaching the DNA molecule means that the device now switches on and off when a matching sequence of DNA becomes attached. Digital signal "The bonds that form between the two strands shift charge around a little and corresponding charge is induced in the quantum dot," explains Louis Brousseau, CEO of Quantum Logic Devices and lead researcher on the project. This switches the current on and off to create a "digital signal," he adds. Brousseau believes the technique could accelerate medical research and the detection of dangerous pathogens. "Researchers currently label DNA molecules using fluorescence, but that can take around 24 hours to produce a result," he says. The new detector can detect a piece of DNA in less than 30 minutes. "The many variables of current procedures make interpretation more art than science," Brousseau adds. "This way produces much more clear-cut results." He thinks the detector would be ideal for diagnosing viruses quickly. "They can replicate very fast so you want to know if someone is infected quickly," he says. "Waiting 24 hours can miss the critical period." Cruddy interference Sub Reddy, a biosensor expert at Surrey University in the UK, says the detectors should be extremely sensitive. "It can detect a single matching sequence, while current methods record the aggregate of many such events," he notes. "It's usually necessary to amplify the DNA in a sample to get a signal, but you could cut that out and perhaps use it in on samples in the field." However, Reddy also sees some drawbacks. "Sample purity becomes important, if you've got one bit of crud in there it could interfere," he warns. 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, Brousseau says.
Omega - 14. Aug, 21:55
