Not yet possible in any useful sense, DNA has the potential to be the backbone for molecular electronic circuits – electronics at the smallest scale – and towards this scientist are hunting through its structure and testing modifications to find useful non-linear electrical characteristics and switching behaviours.
According to the university, the usual way to look at such strands is to catch one long-ways between the microscope probe tip and the substrate, and this reveals that resistance increases with length until nothing much can be measured.
What the Tokyo team did was to measure across the strand instead of along it.
They made one end of the strand ‘sticky’ by bonding sulphur atoms separately each of the single strands that make up the double-stranded helix of the DNA 90-mer.
As sulphur bonds to gold, the sulphur-tipped 90-mers stuck to the substrate by one end (above left).
Conductivity was found to be high, revealed by theoretical modelling to be due to delocalised π electrons that move freely around the molecule, according to the researchers.
“The single plateau and subsequent conductance decay in the traces indicate that these plateaus are attributed to the single-molecule junction that contains DNA,” according to the team in a paper published in Nature Communications.
This and the high conductivity is what leads the researchers, who now have a full theoretical grip on the processes, to conclude that this is useful knowledge for future DNA circuit designers to exploit.
Lastly, if the substrate was coated with one type of ‘half-DNA’ strand and the partner half-strands were deposited on the probe tip, 90-mer DNA spontaneously formed when the probe was moved close to the substrate.
These last two characteristics suggest robust self-assembly should future circuits need it.
Full details can be read without payment in the Nature Communications paper ‘Single-molecule junction spontaneously restored by DNA zipper‘.