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Auto-assembly of proteins for bio-inspired electronics

Researchers from the Chemistry and Biology of Metals laboratory have drawn inspiration from the architecture of bacterial systems in order to develop a conductive nanowire consisting solely of proteins. These results are published in the journal Nature Chemistry.

Published on 30 November 2016
, are used in bioremediation for their ability to "clean up" soils polluted by toxic metals. To do so, these microorganisms have the power to precipitate soluble forms of uranium or chrome, for instance, by performing a reduction. Now how does this relate to electronics ? During this operation of reduction, bacteria transfer electrons. The discovery of the transfer mechanism on Geobacter has initiated a series of original research in bio-nanoelectronics, as this bacteria features conducting wires only a few nanometers in diameter, made up of proteins, on its external membrane. They are called nanowires, or pilin.

"Inspired by the architecture of these bacterial systems, we have developed a conducting nanowire composed only of well-known proteins", says Vincent Forge, Head of team at the Chemistry and Biology of Metals laboratory. Although these bacteria may be "well known", they nonetheless originate from biochemistry. "The nanowire is made using a chimeric protein, which means custom in our lab. It comprises a prion domain, capable of self-assembling into amyloid fibers, and a domain that acts as an electron carrier (a rubredoxin)," Forge explains. It must be noted that the prion domain belongs to the family of healthy prions and not to those implied in mad-cow type pathology. The presence of the prion domain leads to the formation of a fiber through a self-assembling process. Then, this fiber displays rubredoxins on its surface that are close enough (less than 1 nm) for the electrons to be transported throughout the fiber in successive leaps. "We have shown that our protein nanowires allow to transport electrons between a glassy carbon electrode and an enzyme across a distance of several microns" says Forge.

These nanowires should allow for the development of biocompatible and biodegradable electronic components, which could be integrated in medical devices such as biosensors and biobatteries, and also in disposable electronic systems.

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