ISSN:
1040-0397
Keywords:
Biosensor
;
Glucose
;
Glucose oxidase
;
Amperometric glucose electrode
;
Enzyme immobilization
;
α-Cyclodextrin polymer
;
Benzoquinone mediator
;
Tetrathiafulvddene mediator
;
Molecular inclusion
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A highly permeable film of the condensation α-cyclodextrin polymer (α-CDP) was used as a membrane for fabricating a “second-generation” glucose amperometric biosensor. Glucose oxidase (GOD) was covalently immobilized, whereas 1,4-benzoquinone (BQ), or tetrathiafulvalene (TTF) mediator molecules were included in the membrane by the α-cyclodextrin sites. A simple one-step procedure for the biosensor preparation was developed. It consisted of casting the membrane onto the surface of a glassy carbon, gold, or platinum disk substrate from an aqueous solution, pH 2.0 (HCl), containing equimolar quantities of a water-soluble α-cyclodextrin prepolymer, a glutaric dialdehyde cross-linking reactant, GOD, and the mediator. Cyclic voltammetry (CV) limiting currents for glucose biocatalytic electrooxidation were measured for different enzyme loadings and mediator dosings inside the membrane as well as for different glucose conoentrations in a (0.1 M phosphate buffer + 0.1 M NaClO4) pH 7.0 solution. The limiting-electrocatalytic currents at the (α-CDP)-GOD-TTF electrode were pH independent and occurred at E1/2 = 0.03 V (vs. SCE), i.e., at a favorably low potential value. The detectability of glucose was 10 μM for the (α-CDP)-GOD-BQ electrode at the 2 mg (18.5 unit) GOD loading and a signal-to-noise ratio of 3. The values of apparent Michaelis constant for glucose and the maximum limiting electrocatalytic current density, determined from the Michaelis-Menten analysis for the 1 mg (18.5 unit) GOD loading, were (4.5 ± 0.5) mM and (190 ± 20) μA cm-2 for the (α-CDP)-GOD-BQ electrode, and (5.6 ± 0.8) mM and (137 ± 16) μA cm-2 for the (α-CDP) GOD-TTF electrode, respectively. The sensor performance was examined with respect to the method of membrane preparation, membrane composition, and long-term stability. Miniaturization of the biosensor is facile if, for instance, a 10 μm Pt disk microelectrode substrate is used.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elan.1140061104
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