An effective ratiometric electrochemical sensor for highly selective and reproducible detection of ochratoxin A: Use of magnetic field improved molecularly imprinted polymer

Ochratoxin A (OTA) can cause various diseases due to its severe toxicity, so its detection in foods is very important. Herein, a ratiometric electrochemical sensor based on molecularly imprinted polymer (RECS-MIP) has been developed for OTA detection. The MIP is prepared by cyclic voltammetry; during electropolymerization a magnetic field is introduced to regulate the MIP orientation for improving molecular recognition efficiency. A gold nanoparticles, ploy(ionic liquid) and flavin mononucleotide decorated carbon nanotubes - MoS2 nanosheet composite (Au NPs/PIL-FMNS/CNT-MoS2) is used as substrate to amplify signal and to provide reference signal. The peak current of Au NPs/PIL-FMNS/CNT-MoS2 decreases with the increase of OTA concentration, while the peak current of OTA oxidation product increases. The ratio of the peak currents changes linearly with OTA concentration variation and is used for OTA quantification. Under the optimized conditions, the linear response range is 0.5–15 μM and the low limit of detection is 14 nM (S/N = 3). The sensor displays high selectivity and reproducibility and has good application potential; it has been applied for the OTA detection in spiked samples and satisfactory results are achieved.