title: Mediated glucose enzyme electrodes by cross-linking films of osmium redox complexes and glucose oxidase on electrodes.
abstract: Here, we report on a novel, versatile approach for the preparation of mediated enzyme electrodes, demonstrated using cross-linked films of glucose oxidase and a range of functionalised osmium complexes on graphite electrodes. Response of enzyme electrodes are optimised by evaluation of glucose response as a function of variation in ratios of [Os(2,2'-bipyridine)2(4-aminomethyl pyridine)Cl](+) redox mediator, polyallylamine support and glucose oxidase enzyme cross-linked using a di-epoxide reagent in films on graphite. Lowering of the redox potential required to mediate glucose oxidation is achieved by synthesis of complexes using (4,4'-dimethyl-2,2'-bipyridine) or (4,4'-dimethoxy-2,2'-bipyridine) as a ligand instead of (2,2'-bipyridine). Enzyme electrodes prepared using the complexes based on dimethoxy- or dimethyl-substituted bipyridines provide glucose oxidation current densities of 30 and 70 μA cm(-2) at 0.2 and 0.35 V applied potential compared to 120 μA cm(-2) at 0.45 V for the initial enzyme electrode, under pseudo-physiological conditions in 5 mM glucose, with stability of signals proving inadequate for long-term operation. Current output and stability may be improved by selection of alternate anchoring and cross-linking methodology, to provide enzyme electrodes capable for application to long-term glucose biosensors and anodes in enzymatic fuel cells.
authors.affiliation: School of Chemistry & Ryan Institute, National University of Ireland Galway, Galway, Ireland.
authors.forename: Peter
authors.initials: P
authors.lastname: Ó Conghaile
authors.forename: Sirisha
authors.initials: S
authors.lastname: Kamireddy
authors.forename: Domhnall
authors.initials: D
authors.lastname: MacAodha
authors.forename: Paul
authors.initials: P
authors.lastname: Kavanagh
authors.forename: Dónal
authors.initials: D
authors.lastname: Leech
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D056831:Coordination Complexes / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005947:Glucose / Q000032:analysis; D005949:Glucose Oxidase / Q000737:chemistry*; D009992:Osmium / Q000737:chemistry*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry
chemical_list: C560551:4,4'-dimethyl-2,2'-bipyridine; D056831:Coordination Complexes; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D011725:Pyridines; D009992:Osmium; D005949:Glucose Oxidase; D005947:Glucose