Amperometric glucose sensing with polyaniline/poly(acrylic acid) composite film bearing covalently-immobilized glucose oxidase: A novel method combining enzymatic glucose oxidation and cathodic O2 reduction

The film of polyaniline/poly(acrylic acid) composite was prepared by electrochemical polymerization of aniline in the presence of poly(acrylic acid). An enzyme electrode was fabricated with the composite film by immobilizing glucose oxidase covalently on its surface. Amperometric glucose sensing was carried out with the enzyme electrode by monitoring O2 consumption accompanying enzymatic glucose oxidation. Prior to the glucose sensing, the electrochemical properties of the composite film were investigated with respect to cathodic O2 reduction. On the basis of the result, the glucose sensing was conducted at applied potential of −0.3 V vs. SCE in a phosphate buffer solution of pH 7.0. The current response was found to increase linearly with an increase in glucose concentration up to 1.1 mM. The sensitivity was 29.9 ± 5.1 μA mM−1 cm−2 with the detection limit of 0.06 ± 0.02 mM (S/N = 3). The response was not affected by such coexisting electroactive compounds as ascorbic acid and acetaminophen.