ISSN:
1040-0397
Keywords:
Glucose
;
Organic-phase biosensors
;
Osmium redox centers
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Glucose oxidase (GOx) electrodes were constructed by complexing GOx with the redox osmium macromolecule, [Os(bpy)2(PVP)20Cl]Cl (abbreviated Os-Polymer). The biosensor produced high catalytic current densities in response to β-D-glucose in solvent media that were up to 100% in acetonitrile. The sensor, which functions by relaying electrons between GOx flavin adenine dinucleotide redox sites {GOx(FAD/FADH2)} and the electrode, showed great improvement in its organic-phase responses in the presence of certain amounts of water. Cyclic voltammograms were analyzed for the elucidation of reaction mechanism and determination of the formal electrode potential (E°′). The electrode potential E°′ decreased as water content of the medium increased. Steady-state responses of the sensor in CH3CN/H2O mixtures, 1 to 35% v/v in H2O, were observed at 450 mV. The kinetic analysis of the steady-state amperometric response of the biosensor was based on a rapid charge propagation within the polymer compared to the enzyme kinetics. Maximum steady-state current density jmax and apparent Michaelis-Menten constant KM were evaluated from electrochemical Eadie-Hofstee plots. Our results show that jmax reached an optimal value of 282 μA cm-2 in CH3CN/H2O (80 + 20% v/v). There was no drastic change in KM for the different CH3CN/H2O media. This indicates that CH3CN does not bind to, or act as a cosubstrate for, the immobilized GOx. Effect of water on sensor response in the polar organic solvent has been explained on the basis of its role in increasing the flexibility of the immobilized GOx active site environment.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elan.1140061111
Permalink
