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A Filter-based Surface Enhanced Raman Spectroscopic Assay for Rapid Detection of Chemical Contaminants
Published on: February 19, 2016
A ratiometric molecularly imprinted electrochemical sensor based on fluorine-doped ferric oxyhydroxide nanorods for
Jifan Chen1, Xuhua Li2, Xiangyu Li1
1Key Laboratory of Chemical Additives for China National Light Industry, Xi'an Key Laboratory of Advanced Performance Materials and Polymers, Shaanxi University of Science & Technology, Xuefu Road, Weiyang District, Xi'an, 710021, China.
Background:
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.
Results:
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.
Significance:
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.
