DNA BASED SENSORS

Nano-sized carbon tubes coated with strands of DNA can create tiny sensors with abilities to detect odors and tastes, according to researchers at the University of Pennsylvania and Monell Chemical Sciences Center.According to the researchers, arrays of these nanosensors could detect molecules on the order of one part per million, akin to finding a one-second play amid 278 hours of baseball footage. Here the nanosensors are tested on five different chemical odorants including methanol and dinitrotoluene, or DNT, a common chemical that is also frequently a component of military-grade explosives. The nanosensors could sniff molecules out of the air or taste them in a liquid, suggesting applications ranging from domestic security to medical detectors. The nanaosensors could sniff molecules out of the air or taste them in the liquid.

Sensor 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'. If they are put together they become an extremely versatile type of sensor, capable of finding tiny amounts of a specific molecule. Given the size of such sensors each carbon nanotube is about a billionth of a meter wide, these systems could be used as passive detection system in almost anylocation. 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.

Likewise, the nanotubes are ideal for signalling when the DNA has captured a target molecule. Nanotubes are extremely sensitive to electrostatic variations in their environment, whether the nanotube is in a liquid or in air.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. The nanotube will then pick up on that change, turning it into an electric signal that can then be reported. In this way an array of 100 sensors with different response characteristics and an appropriate pattern recognition program would be able to identify a weak known odor in the face of a strong and variable background.