Phenols monitoring and Hill coefficient evaluation using tyrosinase-based amperometric biosensors

Sensitive amperometric biosensors for phenols compounds, based on tyrosinase (polyphenoloxidase, PPO) immobilized on a Pt electrode in an electropolymerized poly-amphiphilic pyrrole matrix or cross-linked with glutaraldehyde, were constructed and compared. Steady-state amperometric measurements, performed at −50 mV vs. SCE in aqueous phosphate buffer containing LiClO4 0.1 M (pH 7) as well as in a chloroform solution containing 0.1 M C6H5CH2N(CH3)3Cl, were used in order to compare the electroanalytical and kinetic parameters of the investigated amperometric biosensors in aqueous and nonaqueous media. It was established that the polypyrrole matrix has a higher efficiency for enzyme retention resulting in higher bioelectrode sensitivity, both in aqueous buffer (690 μA M−1) and in chloroform (149 μA M−1).