Amperometric cholesterol and alcohol biosensors based on conducting polymers

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Kimya Bölümü, Türkiye

Tezin Onay Tarihi: 2010

Öğrenci: ÖZLEM TÜRKARSLAN

Danışman: LEVENT KAMİL TOPPARE

Özet:

Cholesterol and ethanol biosensors based on conducting polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-ethylenedioxypyrrole) (PEDOP) were constructed. Cholesterol oxidase (ChOx, from Pseudomonas fluorescens) and alcohol oxidase (AlcOx, from Pichia pastoris) were physically entrapped during electropolymerization of the monomers (Py, EDOT, EDOP) in phosphate buffer containing sodium dodecylsulfate (SDS) as the supporting electrolyte. The amperometric responses of the enzyme electrodes were measured monitoring oxidation current of H2O2 at +0.7 V in the absence of a mediator. Kinetic parameters, such as Km and Imax, operational and storage stabilities, effects of pH and temperature were determined for all entrapment supports. Based on Michaelis-Menten (Km) constants, it can be interpreted that both enzymes immobilized in PEDOT showed the highest affinities towards their substrates. Before testing the alcohol biosensors on alcoholic beverages, effects of interferents (glucose, acetic acid, citric acid, L-ascorbic acid) which might be present in beverages were determined. The alcohol content of the distilled beverages (vodka, dry cin, whisky, rakı) was measured with these biosensors. A good match with the chromatography results (done by the companies) was observed.