Scientists make DNA into electric circuit

Washington: A team of scientists has designed a DNA circuit capable of splitting and combining current, much like an adapter that can connect multiple appliances to a wall outlet.

In the study, published in the journal Nature Nanotechnology, researchers made the iconic double-helix that carries the genetic blueprint for living forms into a tool able to transport charge more stably and efficiently than previous similar designs.

DNA’s properties of self-assembly and its ability to conduct electrical charge over considerable distance make it suited for applications including electronic circuits and nanorobots, Xinhua cited the researchers as saying.

“Splitting and recombining current is a basic property of conventional electronic circuits. We’d like to mimic this ability in DNA, but until now, this has been quite challenging,” said co-author Tao Nongjian from Arizona State University.

Current splitting in DNA structures with three or more terminals is difficult as charge tends to rapidly dissipate at splitting junctions or convergence points, Tao said.

In the study, a special form, known as G-quadruplex (G4) DNA, is used to improve charge transport properties. G4 DNA is composed of four rather than two strands of DNA that are rich in the nucleotide guanine.

“DNA is capable of conducting charge, but to be useful for nanoelectronics, it must be able to direct charge along more than one path by splitting or combining,” said co-author Zhang Peng from Duke University.

“We have solved this problem by using the guanine quadruplex (G4) in which a charge can arrive on a duplex on one side of this unit and go out either of two duplexes on the other side.”

The G4 structure allowed researchers, for the first time, to design effective conducting pathways between the stacked G-quadruplex DNA and the double-stranded wires that form the terminals for either splitting or merging electrical current flow.

Researchers said that earlier efforts to create such a Y-shaped electrical junction using conventional double-stranded DNA had failed but using G4 DNA as a connector element in multi-ended DNA junctions was shown to dramatically improve charge transport.

“This is the first step needed to transport charge through a branching structure made exclusively of DNA. It is likely that further steps will result in successful DNA-based nanoelectronics that include transistor-like devices in self-assembling pre-programmed materials,” said Zhang.

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