ISSN:
0952-3499
Keywords:
ferrocene
;
cyclodextrin
;
inclusion complex
;
biosensor
;
glucose oxidase
;
biocatalysis
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Inclusion complexes of 1,1′-dimethylferrocene (DMFe) with α-, 2-hydroxypropyl-β- or γ- cyclodextrins were formed in aqueous systems. For the first time, the interacting DMFe-cyclodextrin systems have been characterized using cyclic voltammetry which enabled the estimation of the complexation order, the formation constant and the diffusivity. Cyclic voltammetry was performed at a stationary electrode, yielding complexation ration of 1:2 for DMFe with α-cyclodextrin and 1:1 with the other two cyclodextrins, as expected from the known cavity dimensions for the cyclodextrins. Formation constants of 4.4 × 104 M-2, 1.2 × 103 M-1 and 2.9 × 102 M-2 were than determined for the complexes between DMFe and the α-, β-, and γ-cyclodextrins, respectively, in relative agreement with the literature. The maximum complexation efficiency, diffusivity and solubility were observed for the DMFe:2-hydroxypropyl-β-cyclodextrin inclusion complex, which, combined with cost factors, resulted in the selection of this form for bioelectrocatalysis studies. The efficiency of the complex as a mediator for the glucose: glucose oxidase system was determined by measuring the rate constant (kS) for reaction of the oxidized DMFe with the reduced enzyme. The kS value decreased from 3.4 × 104 M-1 s-1 to 1.9 × 104 M-1 s-1 with an increase in 2-hydroxypropyl-β-cyclodextrin concentration from 4mM. In this range, the ks value is similar to that of free ferrocene, implying a high efficiency of the DMFe:2-hydroxypropyl-β-cyclodextrin inclusion complex.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmr.300080123
