title: High current density PQQ-dependent alcohol and aldehyde dehydrogenase bioanodes.
abstract: In this paper, we explore the bioelectrooxidation of ethanol using pyrroloquinoline quinone (PQQ)-dependent alcohol and aldehyde dehydrogenase (ADH and AldDH) enzymes for biofuel cell applications. The bioanode architectures were designed with both direct electron transfer (DET) and mediated electron transfer (MET) mechanisms employing high surface area materials such as multi-walled carbon nanotubes (MWCNTs) and MWCNT-decorated gold nanoparticles, along with different immobilization techniques. Three different polymeric matrices were tested (tetrabutyl ammonium bromide (TBAB)-modified Nafion; octyl-modified linear polyethyleneimine (C8-LPEI); and cellulose) in the DET studies. The modified Nafion membrane provided the best electrical communication between enzymes and the electrode surface, with catalytic currents as high as 16.8 ± 2.1 µA cm(-2). Then, a series of ferrocene redox polymers were evaluated for MET. The redox polymer 1,1'-dimethylferrocene-modified linear polyethyleneimine (FcMe2-C3-LPEI) provided the best electrochemical response. Using this polymer, the electrochemical assays conducted in the presence of MWCNTs and MWCNTs-Au indicated a Jmax of 781 ± 59 µA cm(-2) and 925 ± 68 µA cm(-2), respectively. Overall, from the results obtained here, DET using the PQQ-dependent ADH and AldDH still lacks high current density, while the bioanodes that operate via MET employing ferrocene-modified LPEI redox polymers show efficient energy conversion capability in ethanol/air biofuel cells.
authors.affiliation: Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil; Departments of Chemistry and Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, United States.
authors.forename: Sidney
authors.initials: S
authors.lastname: Aquino Neto
authors.affiliation: Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil.
authors.forename: David P
authors.initials: DP
authors.lastname: Hickey
authors.affiliation: Departments of Chemistry and Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, United States.
authors.forename: Ross D
authors.initials: RD
authors.lastname: Milton
authors.affiliation: Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil.
authors.forename: Adalgisa R
authors.initials: AR
authors.lastname: De Andrade
authors.affiliation: Departments of Chemistry and Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, United States. Electronic address: minteer@chem.utah.edu.
authors.forename: Shelley D
authors.initials: SD
authors.lastname: Minteer
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000444:Aldehyde Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001674:Bioelectric Energy Sources / Q000382:microbiology; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry; D005465:Fluorocarbon Polymers / Q000737:chemistry; D020576:Gluconobacter / Q000201:enzymology* / Q000378:metabolism; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry; D010084:Oxidation-Reduction; D045542:PQQ Cofactor / Q000378:metabolism*; D011094:Polyethyleneimine / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D005296:Ferrous Compounds; D005465:Fluorocarbon Polymers; D037742:Nanotubes, Carbon; C050099:1,1'-dimethylferrocene; C040402:perfluorosulfonic acid; D000431:Ethanol; D045542:PQQ Cofactor; D011094:Polyethyleneimine; D000426:Alcohol Dehydrogenase; D000444:Aldehyde Dehydrogenase
keywords: Alcoholic biofuel cell; Direct electron transfer; Ferrocene mediators; PQQ-dependent alcohol dehydrogenase; PQQ-dependent aldehyde dehydrogenase