Enhancement of Electricity Production of Microbial Fuel Cells by Using DNA Nanostructures as Electron Mediator Carriers

Abstract

Microbial fuel cells (MFCs) are recognized as eco-friendly technology to convert chemical energy from waste into electricity by biocatalytic microorganisms and biomass as fuel feedstocks. Here, a three-dimensional DNA origami nanostructure serving as electron mediator-methylene blue (MB) carriers was first employed to enhance the electron production and transfer in the anode compartment of Escherichia coli system-based MFCs. By loading MB molecules on DNA origami nanostructures, the MFC with the MB/DNA origami-modified carbon felt (CF) electrode showed the highest voltage production (64 mV) and power density (5.78 mW/m²) compared to bare CF and MB-modified CF electrodes. The enhanced MFC performance was attributed to the larger interface area of DNA origami-assisted MB loading and a biocompatible bacterial growth environment on the anode, which led to E. coli adhesion and fast electron transfer. Furthermore, the MFC with MB/DNA origami modifications could stably operate for three cycles (20 days) with constant voltage discharge without further addition of media. These results show that DNA origami is a promising material serving as an electron mediator carrier for sustainable energy systems, which could get over the drawbacks of carrier-free MFCs, such as short lifetime, continuously adding supplies, and toxicity to both the microorganisms and the natural environment.