Bioelectrocatalysis is a green, sustainable, efficient method to produce value-added chemicals, clean biofuels and degradable materials. As an alternative approach to modern biomanufacturing technology, bioelectrocatalysis fully combines the merits of both biocatalysis and electrocatalysis to realize the green, efficient production of target products from electricity. Here, we review the development status of bioelectrocatalysis, discussing the current challenges and looking toward future development directions. First, we detail the structure, function and modification methods of bioelectrocatalysis. Next, we describe the mechanism of electron transfer, including mediated electron transfer and directed electron transfer. Third, we discuss the impact of the electrode on bioelectrocatalysis. Then we analyse and summarize the application of bioelectrocatalysis methods in the production of chemicals, biofuels and materials. Finally, we detail future developments and perspectives on bioelectrocatalysis for electrosynthesis. Electrochemical reactions can provide necessary redox equivalents for biocatalysis. In this Review, Minteer and co-workers summarize the current status and challenges of enzymatic and microbial bioelectrocatalysis for the green and efficient production of target products using electricity.

The progress and outlook of bioelectrocatalysis for the production of chemicals, fuels and materials

This article introduces a carbon electrode designed to achieve efficient enzymatic electrolysis by exploiting a hierarchical pore structure based on macropores for efficient mass transfer and mesopores for high enzyme loading. Magnesium oxide-templated mesoporous carbon (MgOC, mean pore diameter 38 nm) was used to increase the effective specific surface area for enzyme immobilization. MgOC particles were deposited on a current collector by an electrophoretic deposition method to generate micrometer-scale macropores to improve the mass transfer of glucose and electrolyte (buffer) ions. To create a glucose bioanode, the porous-carbon-modified electrode was further coated with a biocatalytic hydrogel composed of a conductive redox polymer, deglycosylated flavin adenine dinucleotide-dependent glucose dehydrogenase (d-FAD-GDH), and a cross-linker. Carbohydrate chains on the peripheral surfaces of the FAD-GDH molecules were removed by periodate oxidation before cross-linking. The current density for the oxidati...

Exceptionally High Glucose Current on a Hierarchically Structured Porous Carbon Electrode with “Wired” Flavin Adenine Dinucleotide-Dependent Glucose Dehydrogenase

Enzymatic biofuel cells generate electrical energy from renewable sources with high selectivity and environmental benefits compared to lithium batteries and traditional fuel cells For enzymatic fuel cells to become competitive, major improvements in electrode design are required to enhance power density, voltage output, and stability Here we have developed a freestanding paper biofuel cell comprising redox molecule embedded multiwalled carbon nanotube papers for electrical wiring of enzymes The drop-coat and one-pot fabrication methods provide flexibility and permit easy scalability of functionalized bioelectrodes via commercially available materials Buckypaper functionalized with 1,10-phenanthroline-5,6-dione (PLQ) as an efficient electron mediator for fungal-derived FAD-dependent glucose dehydrogenase (FADGDH) shows very high steady-state current densities for glucose oxidation of Imax = 538 ± 054 mA cm–2 at 015 V vs SCE at neutral pH When coupled with a bioinspired protoporphyrin IX buckypaper 

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A High Power Buckypaper Biofuel Cell: Exploiting 1,10-Phenanthroline-5,6-dione with FAD-Dependent Dehydrogenase for Catalytically-Powerful Glucose Oxidation

The flavoenzymes flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) and oxidase (FAD-GOx) do not undergo direct electron transfer (DET) at conventional electrodes, because the flavin adenine dinucleotide (FAD) cofactor is buried deeply (∼1.4 nm) below the protein surface. We present a mediator-less DET between oxygen-insensitive FAD-GDH and single-walled carbon nanotubes (SWCNTs). A glucose-concentration-dependent current (GCDC) is observed at the electrode with the combination of glycosylated FAD-GDH and debundled SWCNTs; the GCDC, because of an increase in the polarized potential during potential sweep voltammetry, increases steeply (+0.1 V of onset, 1.2 mA cm–2 at +0.6 V 48 mM glucose) without the appearance of the FAD redox peak at −0.45 V. In the control experiment, the GCDC is not observed at the counterpart with either bundled SWCNTs or debundled multiwalled carbon nanotubes (MWCNTs). In the control experiment, the GCDC is observed at an analogous electrode based on oxygen-sensit...

Mediatorless Direct Electron Transfer between Flavin Adenine Dinucleotide-Dependent Glucose Dehydrogenase and Single-Walled Carbon Nanotubes

Dawson-type polyoxometalate nanoclusters confined in a carbon nanotube matrix as efficient redox mediators for enzymatic glucose biofuel cell anodes and glucose biosensors.

Glucose oxidation catalyzed by FAD-dependent glucose dehydrogenase within Os complex-tethered redox polymer hydrogel

An amphiphilic aryl-ether AB2-type dendron（1）bearing oligo ethylene glycol（OEG）chains exhibited lower critical solution temperature behavior in aqueous solutions. In the presence of the salting-out salts（Na2SO4, NaCl, and NaBr）, the cloud points of 1 decreased linearly with increasing salt concentration. The slope of the linear decrease changed with the anion type in the order, SO42－ > Cl－ > Br－. In the presence of the salting-in salts（NaSCN and NaI）, the cloud points of 1 increased non linearly with increasing salt concentration. The shape of these curves can be well fitted by adding a Langmuir binding isotherm to the linear term used for the salting-out salts. When monohydric alcohols（ethanol and 1-propanol）were added to the aqueous solutions of 1, the cloud points barely changed but were reduced after adding polyhydric alcohols（ethylene glycol, xylitol, and D-sorbitol）. The salt effect on the cloud points of 1 was negligible in the aqueous polyhydric alcohol solutions. Conversely, the addition of monohydric alcohols to the aqueous solutions could amplify the salt effect on the cloud points. The alkyl groups of monohydric alcohols could be hydrated by water molecules accompanied by the formation of a hydration shell with a clathrate-like structure. Hence, free water molecules are consumed by adding monohydric alcohols to the aqueous solutions. Overall, the amplifi cation of the salt eff ect on the clouding points of 1 could be deduced by increasing the salt concentration around 1. 

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Aya Matsunaga

Papers

Glucose oxidation catalyzed by FAD-dependent glucose dehydrogenase within Os complex-tethered redox polymer hydrogel

LCST behavior of amphiphilic aryl-ether AB-type dendron bearing OEG chains