Dual-Mode sensing platform for zearalenone determination based on HCR signal amplification and magnetic separation using Spectrophotometry and electrochemistry

Zearalenone (ZEN) is a highly dangerous mycotoxin that is lethal to both humans and animals. Herein, a dual-mode biosensor with electrochemical and colorimetric features was proposed for ZEN detection using hybrid chain reaction (HCR) and streptavidin-modified magnetic beads (SA-MBs) as signal amplifier. Among them, the biotin-modified ZEN-cDNA was enriched by the SA-MBs through the specific binding of streptavidin and biotin. When the target is present, ZEN-Apt binds to the target and releases the ZEN-cDNA to trigger HCR. Methylene blue can be inserted into dsDNA as a signaling molecule, so the higher the concentration of the target, the more HCR is triggered, producing more double-stranded DNA and amplifying the signal. Conversely, the more HCR is triggered, the less DNA remains in the solution, resulting in lower absorbance. Therefore, the concentration of the detected substance is proportional to the electrochemical signal and inversely proportional to the photochemical signal. Under optimized conditions, the electrochemical detection range is 1.0 × 10⁻⁹ mol/L − 5.0 × 10⁻⁷ mol/L. In short, the dual-mode biosensor boasts distinct advantages, such as operational simplicity, cost efficiency, signal stability, and considerable potential for broad applications in food safety and environmental monitoring.