title: Redox hydrogel based bienzyme electrode for L-glutamate monitoring.
abstract: Amperometric bienzyme electrodes based on coupled L-glutamate oxidase (GlOx) and horseradish peroxidase (HRP) were constructed for the direct monitoring of L-glutamate in a flow injection (FI)-system. The bienzyme electrodes were constructed by coating solid graphite rods with a premixed solution containing GlOx and HRP crosslinked with a redox polymer formed of poly(1-vinylimidazole) complexed with (osmium (4-4'-dimethylbpy)2 Cl)II/III. Poly(ethylene glycol) diglycidyl ether (PEGDGE) was used as the crosslinker and the modified electrodes were inserted as the working electrode in a conventional three electrode flow through amperometric cell operated at -0.05 V versus Ag¿AgCl (0.1 M KCl). The bienzyme electrode was optimized with regard to wire composition, Os-loading of the wires, enzyme ratios, coating procedure, flow rate, effect of poly(ethyleneimine) addition, etc. The optimized electrodes were characterized by a sensitivity of 88.36 +/- 0.14 microA mM(-1) cm(-2), a detection limit of 0.3 microM (calculated as three times the signal-to-noise ratio), a response time of less than 10 s and responded linearly between 0.3 and 250 microM (linear regression coefficient = 0.999) with an operational stability of only 3% sensitivity loss during 8 h of continuous FI operation at a sample throughput of 30 injections h(-1).
authors.affiliation: Department of Chemistry, Addis Ababa University, Ethiopia.
authors.forename: A
authors.initials: A
authors.lastname: Belay
authors.forename: A
authors.initials: A
authors.lastname: Collins
authors.forename: T
authors.initials: T
authors.lastname: Ruzgas
authors.forename: P T
authors.initials: PT
authors.lastname: Kissinger
authors.forename: L
authors.initials: L
authors.lastname: Gorton
authors.forename: E
authors.initials: E
authors.lastname: Csöregi
mesh_terms: D000594:Amino Acid Oxidoreductases; D015374:Biosensing Techniques; D018698:Glutamic Acid / Q000032:analysis*; D006108:Graphite; D006735:Horseradish Peroxidase; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007202:Indicators and Reagents; D008839:Microelectrodes; D009474:Neurons / Q000737:chemistry; D010084:Oxidation-Reduction; D011199:Potentiometry
chemical_list: D007202:Indicators and Reagents; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D018698:Glutamic Acid; D006108:Graphite; D006735:Horseradish Peroxidase; D000594:Amino Acid Oxidoreductases; C023061:L-glutamate oxidase