Controlling the Carbon-Bio Interface via Glycan Functional Adlayers for Applications in Microbial Fuel Cell Bioanodes.

Alessandro Iannaci,Eoin M Scanlan,Frédéric Barrière,Timothé Philippon,Adam Myles,Paula E Colavita

doi:10.3390/molecules26164755

Abstract

Surface modification of electrodes with glycans was investigated as a strategy for modulating the development of electrocatalytic biofilms for microbial fuel cell applications. Covalent attachment of phenyl-mannoside and phenyl-lactoside adlayers on graphite rod electrodes was achieved via electrochemically assisted grafting of aryldiazonium cations from solution. To test the effects of the specific bio-functionalities, modified and unmodified graphite rods were used as anodes in two-chamber microbial fuel cell devices. Devices were set up with wastewater as inoculum and acetate as nutrient and their performance, in terms of output potential (open circuit and 1 kΩ load) and peak power output, was monitored over two months. The presence of glycans was found to lead to significant differences in startup times and peak power outputs. Lactosides were found to inhibit the development of biofilms when compared to bare graphite. Mannosides were found, instead, to promote exoelectrogenic biofilm adhesion and anode colonization, a finding that is supported by quartz crystal microbalance experiments in inoculum media. These differences were observed despite both adlayers possessing thickness in the nm range and similar hydrophilic character. This suggests that specific glycan-mediated bioaffinity interactions can be leveraged to direct the development of biotic electrocatalysts in bioelectrochemical systems and microbial fuel cell devices.

Highlights

The accumulation of greenhouse gases in the atmosphere coupled to the world’s energy consumption rate is fueling a scientific and economic drive to increase exploitation of alternative renewable and sustainable energy sources
Organic adlayers of phenyl-lactosides and phenyl-mannosides were immobilized on on conductive substrates using electrochemically from aqueous conductive substrates using electrochemically assisted assisted grafting grafting from aqueous solutions.soluThe aryldiazonium salts of 4-aminophenol-αD -mannopyranose (PhOMan) aryldiazonium salts of 4-aminophenol-αD-mannopyranose (PhOMan) and
These results are in agreement with trends in surface adsorption in the presence of wastewater inoculum observed via QCM measurements, which showed that adsorption is inhibited on phenyl-lactoside-modified surfaces when compared to phenyl-mannosides

Summary

Introduction

The accumulation of greenhouse gases in the atmosphere coupled to the world’s energy consumption rate is fueling a scientific and economic drive to increase exploitation of alternative renewable and sustainable energy sources. Population growth is contributing to carbon emissions, waste generation, and their associated energy demands. Microbial fuel cell (MFC) technologies could contribute new solutions, in the context of the NextGenerationEU program [6], as they enable sustainable utilization of resources and improved valorization of waste streams [7,8,9]. MFC devices exploit the ability of specific bacteria called exoelectrogens to oxidatively metabolize organic matter and transfer electrons during the respiration process outside their cellular membrane to Molecules 2021, 26, 4755 ability of specific bacteria called exoelectrogens to oxidatively metabolize organic matter and transfer electrons during the respiration process outside their cellular membrane to a solid electrode through a cascade of redox reactions [1,2,10].

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Conclusion