Researchers at the Karlsruhe Institute of Technology (KIT) in Germany are developing "microbial cyborgs" that generate usable electricity by combining Shewanella oneidensis bacteria with a nanocomposite material.
Today, all electric devices are lifeless lumps of technology powered by equally lifeless batteries and other energy sources. However, if the KIT concept is brought to a practical stage, we could see biosensors and tiny fuel cells, or one day even smartphones and the like, running on electricity supplied by microscopic cyborgs.
As anyone who has had the misfortune to touch an electric eel or step on a torpedo fish can attest, living organisms can generate surprising amounts of electricity. This is true not only of fish, but even down on the microbial level with certain species of bacteria. These exoelectrogenic bacteria naturally produce electrons as part of their metabolic processes, which then migrate to the exterior surface of the single-cell organism. The problem is that this electricity is very difficult to control or even to pick up on an electrode.
The KIT team, led by Professor Christof M. Niemeyer, has created a scaffolding for the Shewanella oneidensis bacteria consisting of a porous hydrogel made up of carbon nanotubes and silica nanoparticles interwoven by DNA strands. This nanocomposite scaffolding turns out to be very attractive to the exoelectrogenic bacteria, causing them to settle on it while other species, like E. Coli, do not.
According to the team, this scaffold not only supports the bacteria for several days, it also acts as a conductor, producing electrochemical activity that can be picked up by an electrode. In addition, by adding an enzyme that cuts the DNA strands, the scientists can control the process.
"As far as we know, such a complex, functional biohybrid material has now been described for the first time," says Niemeyer. "Altogether, our results suggest that potential applications of such materials might even extend beyond microbial biosensors, bioreactors, and fuel cell systems."
The research was published in ACS Applied Materials & Interfaces.
