The corresponding biosensors are based on the bi-enzyme system containing two enzymes, protease and oxidase. Recently, Freeman et al. developed a chemically modified-ISFET fabricated by incorporating 3-aminophenylboronic acid for analyzing the behaviours of dopamine and tyrosinase (TR) [71].
Upon formation of the boronate–dopamine complex on the gate surface, variations in the electrical potential were clearly observed, and then the detection limit of 7 × 10−5 M was determined, showing good performance of this system for the monitoring of dopamine and TR.