title: Synergistic effect of mediator-carbon nanotube composites for dehydrogenases and peroxidases based biosensors.
abstract: Very sensitive, low cost and reliable NADH and H(2)O(2) sensors were realised and used for development of enzyme based biosensors. The active surface of the electrodes was modified with a nanocomposite obtained by modification of SWNT with a proper mediator: Meldola Blue (for NADH) and Prussian Blue (for H(2)O(2)). Low applied potential of -50 mV vs. Ag/AgCl reference electrode proved the synergistic effect of nanocomposite materials towards NADH and H(2)O(2) detection. Biosensors for malic acid and alkylphenols have been developed, using mediator-functionalized-SWNT-based electrodes and two different classes of enzymes: NAD(+)-dependent dehydrogenases and peroxidases. Immobilization of the enzymes was realised using a series of different procedures - adsorption, Nafion membrane, sol-gel and glutaraldehyde, in order to find the best configuration for a good operational stability. A higher sensitivity comparing with other reported biosensors of about 12.41 mA/M.cm(2) was obtained for l-malic acid biosensor with enzyme immobilised in Nafion membrane. Phenol, 4-t-octylphenol and 4-n-nonylphenol were used as standard compounds for HRP based biosensor. Fast biosensor response and comparable detection limit with HPLC methods were achieved.
authors.affiliation: Laboratory of Quality Control and Process Monitoring, University of Bucharest, 4-12 Regina Elisabeta, 030018 Bucharest, Romania.
authors.forename: Adina
authors.initials: A
authors.lastname: Arvinte
authors.forename: Lucian
authors.initials: L
authors.lastname: Rotariu
authors.forename: Camelia
authors.initials: C
authors.lastname: Bala
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Gurban
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002138:Calibration; D002384:Catalysis; D004563:Electrochemistry; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D005295:Ferrocyanides / Q000737:chemistry / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D009243:NAD / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry / Q000378:metabolism; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010636:Phenols / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D004800:Enzymes, Immobilized; D005295:Ferrocyanides; D008293:Malates; D037742:Nanotubes, Carbon; D010078:Oxazines; D010636:Phenols; D009243:NAD; C005559:Meldola blue; C030298:malic acid; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D006735:Horseradish Peroxidase; C000170:ferric ferrocyanide