In the current study, a rapid and novel biomimetic nano-enzymelinked immunosorbent assay has been established for the detection of sulfadiazine (SDZ) using Au@SiO 2 nanoparticles labelling as a marker. In this system, gold nanoparticles exhibited intrinsic peroxidase and activity with excellent water-solubility, and the SiO 2 nanoparticles as ideal carries possessed a large surface area and ease of surface functionalization. The molecularly imprinted polymer films were selected as bionic antibody because of its advantages of selective recognition and reusability. Combine the above advantages, the method exhibited good stability, recognition capability and sensitivity. Under the optimal condition, the limit of detection of the immunosorbent assay was 0.2 mg/L. Beef sample spiked with SDZ was analysed, and the recoveries were in the 78.00% to 90.96% range. The assay could be used to detect SDZ residues in pork and chicken samples, and the results were not significantly different from those obtained by highperformance liquid chromatography.

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The excessive use and ingestion of residues of sulfonamides harm the human body and the environment. To meet the requirements of the maximum residue limit specified by the Ministry of Agriculture of China, a rapid detection method urgently needs to be developed. In the present study, a molecularly imprinted polymer (MIP) that could selectively recognize sulfadiazine (SDZ) was prepared using SDZ as the template molecule and methacrylic acid as the functional monomer. Using MIP as biomimetic antibody and Au@Pt@SiO2 nanozyme as a marker, a new biomimetic immunoassay was developed to detect sulfadiazine. Under the optimal conditions, the limit of detection (IC15) and sensitivity (IC50) of this method were 0.09 and 6.1 mg/L, respectively. To determine the accuracy of this method, honey and milk samples spiked with sulfadiazine were analyzed, with recoveries in the range of 70.8%-90.2%. The method was also used for the quantitative analysis of sulfadiazine residues in milk powder and milk samples, producing results which correlated well with those obtained by high-performance liquid chromatography.

This study reports a fluorescence ratio immunosensor method for detecting dibutyl phthalate (DBP) sensitively and specifically using dual-emission carbon quantum dots labelled with amino-modified nucleic acid aptamers. Under optimal experimental conditions, the linearity range of the method for detecting DBP was from 12.5 to 1500 μg/L, with a limit of detection of 5.0 μg/L. Compared with detection results for two structural analogues, this method showed good specificity for DBP. Liquor samples spiked with DBP measured by this method exhibited a standard recovery of 93.2% to 112.4% with a relative standard deviation of 1.59% to 4.54%. The method was used to determine the DBP content in edible oil samples, providing results not significantly different from those obtained by gas chromatography. Compared with the single wavelength emission method, this method had a stronger antiinterference ability and provided more accurate results, so can be used for highly sensitive detection of DBP in food samples.

In this study, a molecularly imprinted polymer (MIP)-fluorescent probe based on hydrophobic CdSe/ZnS quantum dots (CdSe/ZnS@MIP) was designed and synthesized by bulk polymerization for detecting methamidophos (MAP). The CdSe/ ZnS@MIP was characterized by Fourier-transform infrared spectroscopy, thermo-gravimetric analysis and adsorption properties, and it exhibited good adsorption capacity and fluorescent stability, and excellent selectivity. Under optimal conditions, the fluorescence showed a good linear decrease in the range of 3.50 × 10 −7 -0.71 × 10 −3 mol/L with a correlation coefficient of 0.995. The limit of detection of the fluorescent probe was 9.16 × 10 −8 mol/L, and the relative standard deviation of the method for nine replicate analyses of 4.0 × 10 −6 mol/L MAP was 4.1%. Apple and pear samples spiked with MAP at three levels were extracted and determined by the presented method with good recoveries (89.7%-94.9%). The accuracy of the method was verified by gas chromatography for the detection of kidney beans, leek and cucumber samples, and no significant difference was observed for the results of two methods. K E Y W O R D Sfluorescent probe, methamidophos, molecular imprinting, quantum dot How to cite this article: Liu X, Liu Q, Kong F, Qiao X, Xu Z. Molecularly imprinted fluorescent probe based on hydrophobic CdSe/ZnS quantum dots for the detection of methamidophos in fruit and vegetables. Adv Polym