A new tyrosinase biosensor based on covalent immobilization of enzyme on N-(3-aminopropyl) pyrrole polymer film

A conducting polymer film of N-amino substituted pyrrole monomer has been prepared for covalent immobilization of enzyme for biosensing applications, illustrated by tyrosinase (PPO). The tyrosinase enzyme retains its bioactivity when being immobilized on N-substituted pyrrole polymer film by covalent bonding. The enzyme electrode was characterized by UV-Vis and infrared spectroscopy. Phenolic compounds were quantitatively estimated by the direct electrochemical reduction of enzymatically liberated quinone species at −0.2 V vs. Ag/AgCl. The results of amperometric response measurements conducted on enzyme electrode show sensitivity of 57.6, 71.4 and 45.8 mA M−1 cm−2 and a linear response range of 1.8-170.2, 1.3-110.1 and 2.1-168 μM for phenol, catechol and p-cresol, respectively. The biosensor exhibits a lowest detection limit of 0.9, 0.7 and 1.1 μM, for phenol, catechol and p-cresol, respectively and a period of stable sensitivity of 3 months at 4-5 °C.