Breakthrough Sensor Technology for Ultra-Precise Chemical Detection

Electrochemical sensors offer high sensitivity for detecting analytes at ultralow concentrations (nM-pM) but have limited specificity towards target molecules. Nanomaterial modifications are employed to enhance conductivity and catalytic activity. Critically, molecularly imprinted polymers (MIP) provide a solution for specificity by creating selective recognition cavities complementary to the target analyte. Furthermore, dual-signal ratiometric strategies are indispensable to intrinsically correct for matrix effects and environmental fluctuations, ensuring reliable quantification. For the fungicide carbendazim (CBD), crucial for food safety, reliable on-site detection demands overcoming these combined limitations. We thus developed a ratiometric sensor integrating conductivity-enhanced fluorine-doped β-FeOOH nanorods (F-β-FeOOH NRs) with a CBD-specific MIP layer. A novel ratiometric sensor was fabricated by growing F-β-FeOOH NRs on carbon cloth (CC) via one-step hydrothermal synthesis. F-doping was strategically employed to facilitate the electron transfer and enhance the redox reaction of [Fe(CN)6]3-∕4-. A MIP layer was electropolymerized on F-β-FeOOH NRs/CC using CBD as the template and resorcinol/nicotinamide as dual monomers, thereby creating selective recognition sites. The ratiometric mode utilized the CBD oxidation peak (analyte-specific response) and the internal reference signal from [Fe(CN)6]3-∕4- (internal reference). This dual-signal strategy achieved a wide linear range from 1 to 1000 nM with a low detection limit of 25.6 nM. Real-sample analysis in fruits showed a strong correlation with high performance liquid chromatography (HPLC) results, with recoveries ranging between 98.4 % and 105.9 %, confirming its accuracy in complex matrices. This work pioneers the integration of fluorine-doped β-FeOOH NRs with MIP-based ratiometric sensing, significantly enhancing sensitivity and anti-interference capability for pesticide monitoring. The sensor's portability, low cost, and reliability in real samples highlight its practicality for on-site detection of CBD residues in agriculture and food safety. The design strategy paves the way for adapting this platform to detect other environmental contaminants using tailored MIP.