Analytical Sciences

Amperometric Glucose Sensors Fabricated by ElectrochemicalPolymerization of Phenols on Carbon Paste Electrodes Containing Ferroceneas an Electron Transfer Mediator

Yasuo NAKABAYASHI* , *** , Masako WAKUDA* and HiromuIMAI*

*Faculty of Engineering, Kansai University, Yamate, Suita, Osaka564-8680, Japan
**HRC, Kansai University, Yamate, Suita, Osaka 564-8680, Japan

A non-conducting polymer film of phenol and itsderivatives, in which glucose oxidase (GOx) was immobilized, has beenprepared on a carbon paste electrode containing ferrocene byelectrochemical polymerization. Five phenol derivatives (phenol,3-aminophenol, 3-methylphenol, 3-nitrophenol, and 1,3-dihydroxybenzene)were examined; 3-aminophenol was found to be the most suitable monomer forthe fabrication of amperometric glucose sensors. The maximum currentdeltai_max obtained from the Eadie-Hofstee form of theMichaelis-Menten equation decreased with increasing the substituentconstant sigmam; a plot of deltai_max vs.sigmamgave a straight line except for 3-aminophenol. In the case of3-aminophenol, both hydroxyl and amino groups participated in theelectropolymerization and consequently larger amounts of GOx may beimmobilized in this polymer film. This behavior resulted in the highersensitivity to glucose. The response currents of Fc,CP/GOx/PAPO, which wasfabricated by cycling between 0.20 and 1.40 V vs. Ag/AgCl for theelectropolymerization of 3-aminophenol, changed little within a period of40 d. In addition, this glucose sensor could minimize contributions fromthe easily oxidizable compounds, uric acid and L-ascorbicacid. (Keywords: Non-conducting polymer, phenol derivatives, amperometricglucose sensor, carbon paste, ferrocene)

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