Carbon nanotubes increase the efficiency of “nanobionic” bacterial solar cells.

Engineers have found a way to insert carbon nanotubes into photosynthetic bacteria, significantly increasing their electrical output. They even pass these nanotubes on to their offspring when they divide through what the team calls “legacy nanobionics.”

Solar panels are the main source of renewable energy, but their production has a major impact on the environment. As in many other ways, we can use nature’s cues to improve our own devices, in which case photosynthetic bacteria that extract energy from sunlight could be used in microbial fuel cells.

In a new study, the team from the Federal Polytechnic School of Lausanne EPFL gave those bacteria a boost by inserting carbon nanotubes are small coiled sheets of graphene, a material known for its conductivity. Bacteria with the technical implementation of nanotubes could produce 15 times more electricity than their unmodified counterparts from the same amount of sunlight.

Placing nanotubes in bacteria is no easy task, the researchers say, but they did it by decorating their surface with positively charged proteins. This attracts them to the outer membranes of the bacteria, which are negatively charged. It worked on two types of bacteria, Synechocystis and nostocwhich have very different shapes.

But perhaps most intriguingly, when the bacteria divide, they transfer the carbon nanotubes—and thus better electrical properties—to new cells. However, this decreases over time as the concentration of carbon nanotubes is distributed across more and more cells, but it is an interesting proof of concept for what the team calls legacy nanobionics.

“It’s like an artificial limb that gives you capabilities beyond what you can achieve naturally.”said Professor Ardemis Boghossian, author of the study. “Now imagine that your children could inherit these traits from you when they are born. Not only have we given bacteria this artificial behavior, this behavior is also inherited by their offspring. This is our first demonstration of legacy nanobionics.”.

The team says that, in addition to producing new photovoltaic devices, this method of introducing carbon nanotubes could also be useful for monitoring the inner workings of bacteria or for tracking lineage between generations in a population.

The study was: published In the magazine Nature Nanotechnology.

Source: EPFL.