Amperometric glucose sensing with polyaniline/poly(acrylic acid) composite film bearing glucose oxidase and catalase based on competitive oxygen consumption reactions

Abstract

For the purpose of avoiding interference with glucose biosensing caused by coexisting easily oxidizable compounds, the sensing was attempted with an enzyme electrode (PANI/PAA-GOx/Cat) that was fabricated by co-immobilizing glucose oxidase (GOx) and catalase (Cat) on polyaniline/poly(acrylic acid) (PANI/PAA) composite films. The glucose sensing was carried out by monitoring the decrease in the O2 reduction current resulted from competitive consumption of dissolved O2 caused by electrochemical O2 reduction and enzymatic glucose oxidation. It was found that the immobilized Cat reproduced O2 from H2O2 accompanying GOx-catalytic glucose oxidation. As a result, the enzyme electrode gave a wide linear range (up to 1.6 ± 0.0 mM glucose) and a high sensitivity (49.3 ± 0.6 μA cm−2 mM−1) in the glucose sensing due to increased O2 concentration in the vicinity of the enzyme electrode. The linear range and sensitivity of the electrode are obviously higher than those of the enzyme electrode without Cat (PANI/PAA-GOx). In contrast, despite the complexity of the electrode reaction, the detection limit of the PANI/PAA-GOx/Cat (26.5 ± 5.2 μM) was almost same as that of the PANI/PAA-GOx. Moreover, high glucose selectivity was achieved by adopting a bioelectrochemical system which functions at a low potential to avoid the interference of coexisting easily oxidizable compounds.