Researchers Create DNA-Based Sensors for Nano-Tongues and Nano-Noses

According to researchers at the University of Pennsylvania and Monell Chemical Sciences Center, nano-sized carbon tubes coated with strands of DNA can create tiny sensors with abilities to detect odors and tastes. The researchers tested the nanosensors 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.  

Given the size of such sensors each carbon nanotube is about a billionth of a meter wide, the researchers 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, in a process called directed evolution, to recognize a wide variety of targets, including small molecules and specific proteins.

Likewise, the nanotubes are ideal for signaling when the DNA has captured a target molecule.  Single-walled nanotubes are formed from a single sheet of carbon molecules connected together and then rolled.  It is a unique material in which every atom is on both the surface and the interior.  Although nanotubes have many applications, they are extremely sensitive to electrostatic variations in their environment, whether the nanotube is in a liquid or in air.

According to the researchers, 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.

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