A thin shell and “sunny shape” molecular imprinted fluorescence sensor in selective detection of trace level pesticides in river

- A novel LC-imprinted fluorescence sensor based on the ZnO QDs was successfully prepared.
- The shape of the fluorescence sensor was “sunny shape” which could more effective in the adsorption to the LC.
- The “sunny shape” SiO2/ZnO/MIPs provided a new approach to the determination of LC.

This investigation presented a novel strategy for the preparation of hybrid structure silica/ZnO/molecularly imprinted polymers (SiO2/ZnO/MIPs) to fluorescence recognization and detection of the pyrethroids. Firstly, carboxylated SiO2 nanoparticles (Si-NPs) and amino-functionalized ZnO quantum dots (QDs) were linked together by the function of amination under the assistance of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxy-5-pyrrolidinedione (NHS). Next, the “sunny shape” molecular imprinted polymers (MIPs) layers were anchored on the surface of SiO2/ZnO QDs by the technique of atom transfer radical polymerization (ATRP) and surface molecular imprinting. The resulting nanoparticles were characterized by TEM, FT-IR, fluorescence spectra and the adsorptive properties were detected by the UV-vis spectrophotometer. Through the results, the strategy shortened the preparation time and presented more rapid and sensitive detection performance than the traditional methods. The fluorescence detection results demonstrated this material owned special recognition property to the templates, which contributed that the fluorescence intensity decreased linearly with the variation of pyrethroids in the concentration range 1.0-80 μmol L−1 under the optimized conditions and the detection limit was 0.13 μmol L−1. Moreover, the successful applications in practical samples indicated that the synthesis method in this investigation provided a novel way to the pyrethroids detection in river.

This investigation was focused on the application of ATRP in the preparation of fluorescence sensor. Fig. 1 illustrated the synthesis routes of fluorescence sensor. Firstly, the carboxylated Si-NPs were prepared by the modification of APTES and SA on the silica nanoparticles synthesized by Stöber method. Then, ZnO QDs were anchored on the surface of the SiO2 by the function of amidation reaction under the assistance of EDC/NHS. Next, the surface of SiO2/ZnO QDs was fabricated by the EBiB. Finally, the SiO2/ZnO/MIPs which owned specific recognition cavities were obtained in the presence of LC, Am, DVB, CuBr and 2,2′-Bipyridyl by the technique of ATRP and SMIT.155