title: Mixed-valence compound-based biosensor.
abstract: A cobalt(II)hexacyanoferrate-based biosensor has been prepared simply by codeposition of an enzyme, together with the electrochemical formation of a cobalt (II)hexacyanoferrate compound electrochemically. The compound can be generated at a constant potential of -0.05 V (vs. Ag/AgCl). This compound possesses the catalytic property of reducing hydrogen peroxide to water at the operating potential of 0.0 V vs. Ag/AgCl. The mixed-valence compound-based biosensor possesses an unique interference-independent feature, which is important for biomedical application; this feature is attributed to the low overvoltage characteristic of cobalt (II)hexacyanoferrate. The electrochemical glucose biosensor responds to a series of glucose injections with linearity up to 5 mM (with correlation coefficient R = 0.9999) and the sensitivity of the linear portion is 733 nA/(cm2 x mM). The detection limit is 2 x 10(-6)M (S/N = 3). Both the potential-dependent electron transfer rate constant and the apparent Michaelis-Menten constant were studied in rotating disk experiments. The apparent Michaelis-Menten constant, Km' calculated from the slope of the "Lineweaver-Burke" type reciprocal plot is 28 mM. A fast-response characteristic is observed in the rotating disk experiment and the 95% response time is 14.5 sec. No response was observed from the addition of either 2 x 10(-4)M galactose, acetaminophen, ascorbic acid, uric acid, cysteine, tyrosine, dopamine, or 1,4-dihydroxyquinone in the absence and/or in the presence of 5 x 10(-4)M glucose.
authors: Department of Chemistry, Tamkang University, Tamsui, Taiwan, 25137. mslin@mail.tku.edu.tw
authors: M S
authors: MS
authors: Lin
authors: Y C
authors: YC
authors: Wu
authors: B I
authors: BI
authors: Jan
mesh_terms: D015374:Biosensing Techniques; D001709:Biotechnology; D003035:Cobalt; D004563:Electrochemistry; D004579:Electron Transport; D005295:Ferrocyanides; D005947:Glucose / Q000032:analysis; D007700:Kinetics
chemical_list: D005295:Ferrocyanides; D003035:Cobalt; D005947:Glucose