ISSN:
1040-0397
Keywords:
1,1′-dimethylferrocene-2-hydroxypropyl-β-cyclodextrin
;
Inclusion complex
;
Mediator
;
Glucose
;
Glucose oxidase
;
Diffusion
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The mediation of the glucose oxidase (GOx): glucose reaction by 1,1′-dimethylferrocene (DMF) solubilized in 2-hydroxypropyl-β-cyclodextrin (hpβCD) was studied. Cyclic voltammetry (CV) was used to examine the effects of complexation with hpβCD on the oxidation potential of DMF through the analysis of half-wave potentials. This indicated a one-to-one complex between DMF and hpβCD, with a formation constant of (1.2 ± 0.3) × 103 M-1 The working potential for electrodes using the mediator complex could be reduced by minimizing the hpβCD concentration, though a lower limit of 2.5 mM was observed for the 0.5 mM DMF solutions used in this work, below which the DMF became insoluble, and its electrochemistry was not well behaved.Cyclic voltammetry measurements at different scan rates were used to determine kinetic-parameters, resulting in a second-order rate constant for the reaction of oxidized DMF with reduced GOx of 3.4 × 104 M-1 s-1 to 1.9 × 104 M-1 s-1 for solutions containing 4 mM to 10 mM hpβCD. These values are on the order of one-quarter the literature value for free DMF and are in the range reported for ferrocene, indicating that the complexed DMF is able to function as an efficient mediator. The rate constant determined for 2.5 mM hpβCD was anomalously high and probably indicated insolubility of the DMF at this hpβCD concentration. A rate constant versus the hpβCD concentration plot was used as an indication of the lower limit of hpβCD concentration at which reproducible results could be obtained.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elan.1140060506
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