New DNA Sandwich Detects Genetic Damage

A schematic of the DNA wrapped around a nanotube, how it changes with exposure to certain ions, and the fluoresence generated by a laser. CREDIT: Michael Strano and AAAS, Science

Human DNA wrapped around fabricated microscopic structures can detect genetic damage and potential disease inside living cells.

Picture a phone cord wrapped around a pencil.

The carbon nanotube and DNA sandwich might one day join a growing list of tiny probes that could be launched into the human body to monitor health.

Nanodevices are constructed with individual molecules.

In the new device, DNA wraps around the nanotube with a certain shape defined by the negative charges along its backbone, researchers explain. When exposed to ions of calcium, mercury, sodium or other targeted substances, the negative charges are neutralized and the DNA changes shape. This causes it to glow, or fluoresce, at different wavelengths of infrared light.

"The nanotube surface acts as the sensor by detecting the shape change of the DNA as it responds to the presence of target ions," said University of Illinois at Urbana-Champaign graduate student Daniel Heller, lead author of a paper on the work in the Jan. 27 issue of the journal Science.

Other nanoscale sensors are under development. One limitation to using them in real-world situations is that the fluorescence is typically blocked by the body's tissue and hard to detect.

"This is the first sensor of its kind that operates in the near infrared region of the light spectrum," said Michael Strano, a professor of chemical and biomolecular engineering at the university. "This light is so red that it passes through many centimeters of human tissue, and therefore, our sensor could be used in cells while inside of the body."

The DNA is like a scaffold, Strano explained, and it can be tailored to respond to a wide range of substances that can indicate potential for disease.

The work has been done in a lab setting on living cells but has not yet been tried inside a person.

"We are focusing now on [applications] that are relevant to disease detection and treatment," Strano told LiveScience. "The technique can also be used to track newly developed drugs as they travel into various types of cells.  We are only a year or so away from this type of application."

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