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In a collaborative American- Israeli effort, researchers from Ben-Gurion University of the Negev and University of Georgia have created and characterized the world’s smallest diode, which is only one molecule small.
Diodes are electronic elements that allow current to flow in one direction but prevent its flow in the other direction.
It is a central element in common and prolific electronic devices such as smartphones and computers – essentially any electronic appliance.
Prof. Bingqian Xu of the College of Engineering at the University of Georgia and Dr. Yoni Dubi from BGU’s chemistry department headed the research groups in the two universities.
Researchers in Xu’s group took a single DNA molecule constructed from 11 base pairs, and connected it to an electronic circuit (only a few nanometers large). When they measured the current through the molecule, the researchers found that the molecule did not present any unusual behavior. But when the DNA was combined with a molecule named coralyne, the behavior of the circuit changed drastically.
It became 15 times larger for negative voltages than for positive voltages, a necessary feature for a diode. The researchers deduced that they had created a diode composed of a single DNA molecule.
To understand the origin of this feature, Dubi and his student Elinor Zerah-Harush, used the results of the experiment to construct a theoretical model of the DNA molecule inside the electric circuit. The model allowed them to identify the source of the diode-like feature, showing that it originates from the breaking of spatial symmetry inside the DNA molecule after the coralyne is inserted.
The results of this study, which have just been published online in Nature Chemistry, are a “milestone in the creation of molecular electronic devices and shed light on the electronic transport mechanism in DNA ,” Dubi said. The research showed for the first time that one can make tiny electronic elements from single DNA molecules. This could lead to progress in the design and construction of nano-scale electronic elements (the smallest elements available now are typically 1000 times larger), he added.
The two teams are continuing their collaboration, with the aim of constructing more molecular devices and enhancing the performance of the molecular diode.