(ORDO NEWS) — Marine Shewanella oneidensis are widely known as “bacteria that feed on electricity.” In fact, these microbes are able to receive and directly use free electrons to reduce metal oxides. It is not surprising that since their unique abilities were discovered, scientists have not abandoned attempts to turn these bacteria into living sources of “pure” electrical energy.
Unfortunately, in practice, learning how to collect charges from individual cells, living and motile, proved to be quite difficult. The first prototype of a device capable of performing such a task appeared only recently. Its developers – the team of Christof Niemeyer of the Karlsruhe Institute of Technology (KIT) – presented the project in an article published in the journal ACS Applied Materials & Interfaces.
To utilize S. oneidensis ‘ superpowers, scientists have assembled a composite base – a fluid-filled hydrogel consisting of carbon nanotubes and chains of spherical silicon nanoparticles intertwined with long DNA strands.
Laboratory experiments have shown that such structures attract S. oneidensis , but not other bacteria. They populated the composite to its entire depth – while, for example, E. coli only carefully fixed on the surface. According to scientists, the “bio-hybrid composite” remained stable for at least several days. At the same time, he conducted electricity.
Carbon nanotubes acted as an electrode, consisting of a densely interwoven network of thin filaments, and made it possible to collect charged particles from the surface of cells entangled in it. Scientists were able to regulate the operation of such a system using enzymes that cut DNA in a composite, quickly stopping its electrochemical activity.
“Together, this shows that potentially similar materials can be used outside the immediate areas, such as the creation of new biosensors, bioreactors and fuel cells ,” summarizes Christoph Niemeyer.
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