Electronic Diode based on a DNA molecule

By inserting a small “coralyne” molecule into DNA, scientists were able to create a single-molecule diode (connected here by two gold electrodes), which can be used as an active element in future nanoscale circuits. The diode circuit symbol is shown on the left. Credit: University of Georgia and Ben-Gurion University

A diode is one of the basic electronic components. An ideal diode blocks current flowing in one direction and let current flows in the opposite one. In reality a diode blocks most of the current in one direction and let most of the current flow in the the other direction. From the point of view of information transfer it is enough that the difference between the quantity of current in one direction is detectable so that you associate a value of, lets say "1" when current flows and "0" when there is no current.

Chips have diodes made in silicon (transistors are basically a diode with an additional part that controls the amount of current flowing) and we have reached (almost) the end of the line in terms of miniaturisation. Researchers are exploring alternative ways to create diodes, like using graphene. 

In this news, coming from the University of Georgia, US, and Ben Gurion University in Israel, researchers have been experimenting with DNA to create a diode.

DNA strands are very resilient and in a way are pieces of programs; by changing the basic building blocks (the A-C-G-T nucleic acids) you can create different instructions. The researchers used 11 pairs of nucleic acids and inserted a molecule of coralyne creating a molecule that behaves like a diode. They connected this artificial DNA molecule to atomic size wires and proved that it has asymmetric conductivity, i.e. it lets current flows mostly in one direction and not in the other.

Now researchers will study what effect would be produced by using different pairs of nucleic acid in terms of asymmetric conductivity.

The interest in this news is the possibility to create structures with desired properties in a bottom up way. This not only results in smaller structures, it also provides finer control on their properties.

Notice that we are very very far from an industrial application of this discoveries. Nevertheless, they show how nanotechnology can revolutionise our approach to the design of smart materials. The science fiction dream of inserting a computer in a cell to interact with the cell DNA has become a technology issue, we have created a bike but we still need to learn how to ride it.

Author - Roberto Saracco

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