A dual-mode ratiometric aptasensor for ultrasensitive detection of zearalenone via aptamer-mediated signal switching

The escalating global concern over mycotoxin contamination in agricultural products necessitates advanced biosensing technologies for on-site monitoring. This research presents a compact microfluidic ratiometric biosensor that addresses the constraints of traditional systems which depend on large instruments and photoactive materials that are sensitive to wavelength or potential changes. The platform employs a dual-signal self-calibration strategy, integrating a signal-on PEC response from a hematene/ZnO heterojunction with a signal-off electrochemical (EC) signal mediated by methylene blue (MB)-tagged aptamers. Target-induced zearalenone (ZEN) binding triggers aptamer conformational changes: MB detachment attenuates the EC signal, while reduced steric hindrance enhances electron transfer efficiency, restoring PEC activity. This synergistic mechanism autonomously corrects environmental interferences (e.g., light intensity fluctuations, buffer variations) without auxiliary equipment. A suction-driven microfluidic chip automates fluid handling with <10 μL sample consumption. This biosensor demonstrates a linear detection range from 1 × 10 −6  ng/mL to 100 ng/mL, a 5.3 × 10 −6  ng/mL detection limit (S/N = 3). By harmonizing ratiometric self-calibration, nanomaterial-enhanced photoactivity, and lab-on-a-chip automation, this research proposes a deployable model for decentralized biosensing, merging laboratory-level precision with practical point-of-need application in food safety and clinical diagnostics.