title: 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.
authors.affiliation: Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba , 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Tsujimura
authors.forename: Kazuki
authors.initials: K
authors.lastname: Murata
authors.forename: Wataru
authors.initials: W
authors.lastname: Akatsuka
mesh_terms: D002244:Carbon / Q000737:chemistry* / Q000378:metabolism; D004566:Electrodes; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry* / Q000378:metabolism; D005947:Glucose / Q000737:chemistry* / Q000378:metabolism; D042843:Glucose 1-Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D016062:Porosity; D013499:Surface Properties
chemical_list: D005182:Flavin-Adenine Dinucleotide; D002244:Carbon; D042843:Glucose 1-Dehydrogenase; D005947:Glucose