Study On Upconversion Fluorescence Labeling Immunological Assay For The Detection Of Nitenpyram

An upconversion immunization assay for the detection of nitenpyram was developed.The NaYF4:Er3+, Yb3+(OA-UCNPs) which was hydrophobic and had uniform particle size was synthesized through hydrothermal method firstly. In order to form the water-soluble PAA-UCNPs, we used the polyacrylic acid (PAA) to modify and activate the OA-UCNPs through ligand exchange pathway at high temperature.The signal probe was obtained by the nitenpyram polyclonal antibody which was purified through Protein A-epharose4B coupling to the surface of PAA-UCNPs; The sensing probe was obtained through the nitenpyram coating antigen binding to the surface of polystyrene microspheres similarly. Moreover, the addition amount of polyclonal antibody and coating antigen was optimized respectively, which was0.5mg per5mg PAA-UCNPs and0.2mg per2.5mg polystyrene microspheres. We established the standard curve of proposed method when the addition of sensing probe was100μL and incubation reaction time was50min. In addition to, The limit of quantification was1ng/mL and the linear range of1ng/mL-10000ng/mL. Meanwhile the cross-reactivity of nitenpyram with other3neonicotinoids and7different types of pesticides were low, indicating that the assay showed high specificity. The assay was used to detect4spiked vegetable samples (tomato, cabbage, cucumber, Chinese cabbage),4spiked juice samples (tomato juice, orange juice, apple juice, grape juice) and4spiked water samples (pure water, tap water, river water, lake water). We obtained a simple and practical method of sample preparation by optimizing the conditions. The recoveries of vegetable samples was70%-100%, the CV was1.91%-9.40%; The recoveries of juice samples was90%-110%, the CV was1.32%-8.39%; The recoveries of water samples was80%-110%, the CV was2.10%-6.42%respectively, which indicated the proposed method has good accuracy and precision.Through gas chromatography analysis method, we discussed the accuracy of the proposed method finally. The result showed that the consistency of two methods is very good, which indicates the high reliability of the method.The proposed method shows a series of advantages, such as short time-consuming, strong specificity, high sensitivity, small background interference and so on, besides it is suitable for the detection of nitenpyram in agricultural and environmental samples.