A Novel Optosensor for Rapid Detection of Difenoconazole Using Molecularly Imprinted Polymers

A novel molecularly imprinted fluorescent sensor (MIFS) based on glutathione-modified CdTe quantum dots (QDs) was fabricated to detect and determine difenoconazole (DFZ) in agricultural products. Initially, glutathione-modified CdTe QDs were synthesized via the refluxing method. The MIFS was then synthesized by fixing a molecularly imprinted polymer layer on the surface of QDs through a sol-gel process. Transmission electron microscopy, fluorescence spectrometry, dynamic light scattering analysis, X-ray diffraction analysis, and Fourier transform infrared spectroscopy were finally employed to characterize the QDs and the fabricated sensor. In this MIFS, the selectivity of molecular imprinting techniques and the sensitivity of QDs were combined to fabricate for the first time a simple and inexpensive sensor of high selectivity and sensitivity for the detection of DFZ. Fluorescence quenching was observed to occur so that the fluorescence intensity of the MIFS decreases linearly with increasing DFZ concentration in the range of 2.5-124.5 ng/mL with a detection limit of 0.5 ng/mL. Finally, the MIFS was employed to measure DFZ in agricultural products. Good recoveries ranging from 90.1% to 112.2% were obtained, indicating the successful and highly accurate determination of DFZ in agricultural products by the MIFS.