Inhibition of benzoic acid on the polyaniline–polyphenol oxidase biosensor

A polyaniline–polyphenol oxidase (PANI–PPO) biosensor for detecting benzoic acid is reported. The biosensor is based on the inhibition of benzoic acid on the biocatalytic activity of the polyphenol oxidase (PPO). The Michaelis–Menten constant ( k ′ m ) and maximum response current (Imax) in both the absence and presence of benzoic acid are also evaluated. The kinetic analyses show that the inhibition of benzoic acid on the PPO activity is reversible and competitive with an inhibition constant of 28.7 μmol dm−3. A limit of detection of 0.3 μmol dm−3 benzoic acid is obtained. The I0.5 value is estimated to be 35 μmol dm−3. The biosensor has good sensitivity and high stability. So it can be used as a new approach for the detecting benzoic acid.