Passive pumping field-effect transistor microfluidic chip for ultratrace and portable detection of multiple biotoxins...

The coexposure of various biotoxins in aquatic environments poses significant ecological and public health risks. However, detecting multiple biotoxins simultaneously is challenging because of labour-intensive workflows, reliance on bulky equipment, and slow processing and portability and sensitivity, hindering their applicability for on-site monitoring. Herein, we introduce an integrated passive pumping carbon nanotube-based field-effect transistor (CNT-FET) microfluidic chip that combines selective probe functionalisation and detection of various biotoxins with autonomous fluid handling, eliminating the need for external pumps or valves. This platform allows the direct, portable, label free, rapid and sensitive analysis of various biotoxins including okadaic acid, ochratoxin A, zearalenone, gliotoxin and ricin in lake water. It exhibits a broad dynamic range (1 fg/mL to 100 ng/mL), ultralow limit of detection (2.6-9.6 fg/mL) and high recovery rates (88.3 %-116 %). Validation using standard analytical methods such as enzyme-linked immunosorbent assay and high-performance liquid chromatography confirmed the high accuracy and reliability of the proposed microfluidic system. Combining the CNT-FET array with a passive pumping microfluidics chip provides a practical approach for swift on-site biotoxin monitoring, offering wide implications for safeguarding environmental safety and public health. The chip design is modular and easily customisable, allowing do-it-yourself adaptation for analysing other environmental contaminants through autonomous control of specific functional reagent modifications.