According to the researchers, arrays of these nanosensors could detect molecules on the order of one part per million, akin to finding a single person in Times Square on New Years' Eve. The researchers tested the nanosensors on five different chemical odorants, including methanol and dinitrotoluene, or DNT. The nanosensors could sniff molecules out of the air or taste them in a liquid, suggesting applications ranging from domestic security to medical detectors.
"What we have here is a hybrid of two molecules that are extremely sensitive to outside signals: single stranded DNA, which serves as the 'detector,' and a carbon nanotube, which functions as 'transmitter,'" said A. T. Charlie Johnson, associate professor in Penn's Department of Physics and Astronomy. "Put the two together and they become an extremely versatile type of sensor, capable of finding tiny amounts of a specific molecule."
Johnson and his colleagues believe arrays of these sensors could serve as passive detection systems in almost any location. The sensor surface is also self-regenerating, with each sensor lasting for more than 50 exposures to the targeted substances, which means they would not need to be replaced frequently.
The specificity of single-stranded DNA is what makes these sensors so capable. These biomolecules can be engineered to recognize a wide variety of targets, including small molecules and specific proteins. Likewise, the nanotubes are ideal for signalling when the DNA has captured a target molecule.
"When the DNA portion of the nanosensor binds to a target molecule, there will be a slight change in the electric charge near the nanotube," Johnson said. "The nanotube will then pick up on that change, turning it into an electric signal that can then be reported."
COMPAMED.de; Source: University of Pennsylvania