Conductivity-Based Catechol Sensor Using Tyrosinase Immobilized in Porous Silicon

A conductivity-based catechol biosensor was developed using porous silicon as an immobilization matrix for enzyme tyrosinase. The enzyme was extracted from plant source Amorphophallus companulatus and immobilized in an electrochemically etched surface of p-type silicon. The presence of enzyme in a porous structure and the retention of enzyme activity were confirmed by scanning electron microscopy and spectrophotometric studies, respectively. The principle of the sensor is based on the change in the conductivity of the tyrosinase-entrapped porous silicon matrix. When the entrapped tyrosinase interacted with catechol, the change in the current voltage (I-V) characteristics was obtained, which was proportional to analyte concentration. The analytical characteristics of the sensor including response time, linearity range, lower detection limit, reusability, and storage stability were studied.