酸素添加酵素担持ポリアニリン/ポリアクリル酸複合膜によるプロトカテク酸のアンペロメトリックセンシング

抄録

Conducting composite films of polyaniline/poly(acrylic acid) were prepared by electrochemical polymerization of aniline in the presence of poly(acrylic acid). An enzyme electrode was fabricated with the composite film by covalently immobilizing protocatechuate 3,4-dioxygenase on its surface. Amperometric sensing of protocatechuic acid (PCA) was carried out with the enzyme electrode by monitoring O₂ consumption accompanying enzymatic PCA oxidation. The sensing was conducted at an applied potential of −0.3 V vs. SCE in a phosphate buffer solution at pH 7.0. The current response was found to increase linearly with an increase in PCA concentration up to 0.55 mM. The sensitivity was 155 µA mM⁻¹ cm⁻² with the detection limit of 5 µM. The enzyme electrode gave no response to phenolic compounds other than PCA and to electroactive species such as ascorbic acid and acetaminophen. This high selectivity can be attributed to the substrate specificity of protocatechuate 3,4-dioxygenase and the low potential for amperometry.