Towards self-restoring electronic devices with long DNA molecules

Date:
November 2, 2021
Source:
Tokyo Institute of Technology
Summary:
The potential of DNA structural properties in single-molecule
electronics has finally been harnessed by researchers in
a single-molecule junction device that shows spontaneous
self-restoring ability. Additionally, the device, based on
a 'zipper' DNA configuration, shows unconventionally high
electrical conductivity, opening doors to the development of novel
nanoelectronic devices.



FULL STORY ==========================================================================
In every advanced organism, the molecule called DNA (deoxyribonucleic
acid, to use its full name) forms the genetic code. Modern-day technology
takes DNA one step beyond living matter; scientists have established
that the intricate structures of DNA have made it possible for it to
be used in new-age electronic devices with junctions comprising just a
single DNA molecule. However, as with any ambitious endeavor, there are impediments to overcome. It turns out that the single-molecule conductance falls off sharply with the length of the molecule so that only extremely
short stretches of DNA are useful for electrical measurements. Is there
a way around this problem?

========================================================================== There is, indeed, suggest researchers from Japan in a new breakthrough
study.

They have managed to achieve an unconventionally high conductivity
with a long DNA molecule-based junction in a "zipper" configuration
that also shows a remarkable self-restoring ability under electrical
failure. These results have been published as a research article in
Nature Communications.

How did the researchers achieve this feat? Dr. Tomoaki Nishino from Tokyo
Tech, Japan, who was part of this study, explains, "We investigated
electron transport through the single-molecule junction of a 'zipper'
DNA that is oriented perpendicular to the axis of a nanogap between
two metals. This single-molecule junction differs from a conventional
one not only in the DNA configuration but also in orientation relative
to the nanogap axis." The team used a 10-mer and a 90-mer DNA strand
(which indicate the number of nucleotides, basic building blocks of DNA, comprising the molecule length) to form a zipper-like structure and
attached them to either a gold surface or to the metal tip of a scanning tunneling microscope, an instrument used to image surfaces at the atomic
level. The separation between the tip and the surface constituted the
"nanogap" that was modified with the zipper DNA.

By measuring a quantity called "tunneling current" across this nanogap,
the team estimated the conductivity of the DNA junctions against a bare
nanogap without DNA. Additionally, they carried out molecular dynamics simulations to make sense of their results in light of the underlying "unzipping" dynamics of the junctions.

To their delight, they found that that the single-molecule junction
with the long 90-mer DNA showed an unprecedented high conductance. The simulations revealed that this observation could be attributed to a
system of delocalized p-electrons that could move around freely in the molecule. The simulations also suggested something even more interesting:
the single-molecule junction could actually restore itself i.e., go from "unzipped" to "zipped," spontaneously after an electrical failure! This
showed that the single-molecule junction was both resilient and easily reproducible.

In the wake of these discoveries, the team is excited about
their future ramifications in technology. An optimistic
Dr. Nishino speculates, "The strategy presented in our study
could provide a basis for innovations in nanoscale electronics
with superior designs of single-molecule electronics that could
likely revolutionize nanobiotechnology, medicine, and related fields." ========================================================================== Story Source: Materials provided by Tokyo_Institute_of_Technology. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Takanori Harashima, Shintaro Fujii, Yuki Jono, Tsuyoshi Terakawa,
Noriyuki Kurita, Satoshi Kaneko, Manabu Kiguchi, Tomoaki
Nishino. Single- molecule junction spontaneously restored
by DNA zipper. Nature Communications, 2021; 12 (1) DOI:
10.1038/s41467-021-25943-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211102131701.htm

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