Electrochemical biosensor based on tyrosinase-immobilized phase-change microcapsules for ultrasensitive detection of phenolic contaminants under in situ thermal management

Abstract

Aiming at enhancing the detection of phenolic contaminants in high-temperature environments, we developed a thermoregulatory electrochemical biosensor based on the tyrosinase-immobilized electroactive phase-change microcapsules. The microcapsules were fabricated by engulfing n-eicosane as a phase-change material core in a TiO2 shell, followed by depositing with an electroactive hybrid layer comprising the polypyrrole matrix and tyrosinase-immobilized Fe3O4 nanoparticles. The resultant microcapsules show a well-defined core–shell microstructure and a regular spherical morphology, together with the desired chemical compositions and structures. Acting as a biosensing electrode material, the microcapsules exhibit a high latent heat capacity of around 150 J/g to implement microenvironmental temperature regulation for the biosensor through reversible phase transitions of their n-eicosane core. This enables the developed biosensor to obtain a higher enzyme activity and more sensitive biosensing performance at high assay temperatures when compared to conventional tyrosinase biosensors, resulting in a high sensitivity of 0.102 (µA·L)/µmol and a lower detection limit of 3.409 µmol/L for catechol detection. Based on a unique integration of phase-change microcapsules and immobilized tyrosinase in the working electrode, the electrochemical biosensor developed in this study has found a practical application for high-sensitive reorganization and high-accurate determination of phenolic contaminants in industrial wastewaters over a wide working temperature range.