Thermal self-regulatory intelligent biosensor based on carbon-nanotubes-decorated phase-change microcapsules for enhancement of glucose detection

Enzyme-based biosensors are sensitive to temperature due to their strong temperature dependency of catalytic activity. Aiming at enhancing biosensing detection for glucose assay over a wide range of applicable temperatures, we designed a thermal self-regulatory intelligent biosensor through an innovative integration of phase change material (PCM) and bioelectrocatalytic substances. An electroactive phase-change microcapsule system was firstly fabricated by microencapsulating n-docosane as a PCM core in the SiO2 shell, followed by depositing polydopamine along with carbon nanotubes as an electroactive layer on the surface of SiO2 shell. The resultant microcapsules showed a regularly spherical morphology and well-defined core-shell microstructure. They also exhibited a satisfactory latent heat capacity of around 137 J/g for implementing temperature regulation with a good working stability. An electrochemical biosensing system was constructed with the resultant electroactive microcapsules together with glucose oxidase as a redox enzyme, achieving a thermal self-regulation capability to enhance the biosensing detection of glucose under in-situ thermal management at higher temperatures. With a high sensitivity of 5.95 μA⋅mM-1⋅cm-2 and a lower detection limit of 13.11 μM at 60 °C, the intelligent biosensor developed by this study demonstrated a superior determination capability and better detection performance toward glucose than conventional biosensors in a high temperature region thanks to effective regulation of microenvironment temperature in the electrode system. This study provides a promising strategy for the development of thermal self-regulatory smart biosensors with an enhanced identification ability to detect various chemical substances over a wide range of applicable temperatures.