Analytical Sciences

Electrochemical Detection of Biotin Using an Interaction between Avidin and Biotin Labeled with Ferrocene at a Perfluorosulfonated Ionomer Modified Electrode

Shunitz TANAKA* * , Kazuyo YOSHIDA*, Hideki KURAMITZ*, Kazuharu SUGAWARA** and Hiroshi NAKAMURA*

*Division of Material Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
**Kitami Institute of Technology, Kitami, Hokkaido, 090-8507, Japan

The electrochemical behavior of biotin labeled with ferrocene was investigated at a perfluorosulfonated ionomer (Nafion^(R)) film-coated glassy carbon electrode (GCE). The electrode response of the labeled biotin (LB) was improved by about fifty-fold in sensitivity by using a Nafion^(R)-coated GCE, compared with a plain GCE. It was found by a solid-phase avidin-biotin binding assay that the labeling with ferrocene hardly affected the affinity of a biotin moiety in the labeled biotin to avidin. The avidin-biotin interaction was estimated from the change of the electrode response caused by the formation of a complex with avidin and the labeled biotin. Furthermore, the detection of biotin was performed by a competitive reaction between the labeled biotin and unlabeled biotin for the limited binding sites of avidin. (Keywords: Avidin-biotin interaction, labeled biotin with biotin, Nafion^(R)-coated glassy carbon electrode)

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