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

Abstract

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 oxidation of glucose was 100 mA cm(-2) at 25 °C and pH 7, with a hydrogel loading of 1.0 mg cm(-2). For the same hydrogel composition and loading, the current density on the MgOC-modified electrode was more than 30 times higher than that on a flat carbon electrode. On increasing the solution temperature to 45 °C, the catalytic current increased to 300 mA cm(-2), with a hydrogel loading of 1.6 mg cm(-2). Furthermore, the stability of the hydrogel electrode was improved by using the mesoporous carbon materials; more than 95% of the initial catalytic current remained after a 220-day storage test in 4 °C phosphate buffer, and 80% was observed after 7 days of continuous operation at 25 °C.

Redox-Polymers Enable Uninterrupted Day/Night Photo-Driven Electricity Generation in Biophotovoltaic Devices

“…S3 for longer-term performance) to the redox-polymer additions with consistent differences in electrical output throughout the length of the experiments, indicating lack of any toxicity effects and demonstrating the stability of the modifications over time (as previously demonstrated for >6 months in physiological solutions 24 ).…”

Multi-enzyme anode composed of FAD-dependent and NAD-dependent enzymes with a single ruthenium polymer mediator for biofuel cells

“…Recently, enormously high catalytic current densities were observed employing an FAD-GDH modified electrode with magnesium oxide-templated mesoporous carbon particles and a redox hydrogel [15].…”

Effect of Pore Size of MgO-templated Carbon on the Direct Electrochemistry of <small>D</small>-fructose Dehydrogenase

“…We have reported the use of MgOCs with a pore diameter of 38 nm as the enzyme electrode scaffold for glucose anodes using glucose dehydrogenase and glucose oxidase in the presence of a redox mediator and an oxygen cathode using bilirubin oxidase. [21][22][23] In the present study, the electrochemical oxidation reaction of D-fructose with FDH from Gluconobacter frateurii was examined. The effects of the pore size of MgOCs on the direct electron transfer (DET) reaction of FDH were investigated.…”