Analytical Sciences

Application of Polyammonium Cations to Enzyme-immobilized Electrode: Voltammetric Behavior of Polycation-hexacyanoferrate Anion Complexes and Applicability as Electron-Transfer Mediator

Hajime KATANO,* Hirosuke TATSUMI,** Takao HIBI,* Tokuji IKEDA,* and Toshihide TSUKATANI***

* Department of Bioscience, Fukui Prefectural University, Eiheiji-cho, Fukui 910-1195, Japan
** International Young Researchers Empowerment Center, Shinshu University, Matsumoto 390-8621, Japan
*** Research and Development Division, Nicca Chemical, Co. Ltd., Bunkyo, Fukui 910-8670, Japan

Cyclic voltammograms of the aqueous solution containing polyammonium cations and the [Fe(CN)₆]^4-. anion at a plastic-formed carbon or platinum electrode were recorded. Polyammonium salts comprising quaternary ammonium in the main chain or sub chain and those comprising primary ammonium were tested. Under certain conditions, well-developed anodic and cathodic peak currents with the midpoint potentials different from that when the polyammonium cation is absent, that is, the midpoint potential of [Fe(CN)₆]^3- + e^- = [Fe(CN)₆]^4- were exhibited, indicating that the [Fe(CN)₆]^4-/3- anionic species associate with the polyammonium cations tested to form the polycation-[Fe(CN)₆]^4-/3- complex species. The polycation complex species can be easily localized around the electrode surface with a dialysis membrane. An application of the polycation complex species as an electron-transfer mediator in the catalytic electrode with a redox enzyme was examined.

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