The detection of bifenthrin is closely related to the adsorption of SERS substrates. In this study, superparamagnetic Fe3O4@Au MNPs coated with GO were used to detect the adsorption and enrichment of bifenthrin molecules with benzene rings. Firstly, the thermal solvent method synthesized Fe3O4magnetic nanoparticles (MNPs) with a particle size of ~250 nm. Next, polyethylene imide (PEI) was used as an intermediate layer to modify the surface of Fe3O4to form a positively charged ultra-thin polymer middle layer. Next, the gold shell was developed by adsorption of ~20 nm AuNPs, without affecting the magnetic properties. Then, the additional amount of colloidal gold and GO on SERS performance was systematically studied. Using crystal violet (CV) as the probe, we investigated the SERS performance of composite nanomaterials. The lowest detected concentration reached 10−8mol/L, confirming that the composite functional material had good SERS activity and magnetic properties. Finally, the substrate was used to detect bifenthrin in an acetone solution, and the lowest detection concentration was 10−8mol/L. These results showed that the prepared GO/Fe3O4@Au MNPs were efficient SERS substrates that could detect bifenthrin pesticide residue with high sensitivity.
Xuelian Wu,Xiaodong Lv,Jixiang Wang,Lin Sun,Yongsheng Yan
Based on the room-temperature phosphorescence (RTP) peculiarity of Mn-doped ZnS quantum dots (QDs), a bifenthrin sensor was fabricated by coupling molecular imprinted polymers (MIPs) on the surface of silane modified QDs via atom transfer radical polymerization (ATRP). The stepwise synthesis was realized with ZnS QDs-NH2-Br as the initiator, methacrylic acid (MAA) as the functional monomer, divinylbenzene (DVB) as the cross-linker, CuBr as the catalyst and 2,2′-bipyridine as the complexant. The smart RTP probe for bifenthrin was gained by surface molecular imprinting technology (SMIT) that can not only produce the stable RTP intensity of Mn-doped ZnS QDs, but can also enable more efficient recognition of the target molecule. The results presented show that the detection limit of the probe was 16.7 μg L−1. The RTP stability, selectivity and sensitivity of the bifenthrin sensor were evaluated by using a spectrophotometer. The high sensitivity was due to an electron-transfer mechanism between the target and the QDs, and the particular selectivity was due to SMIT. Therefore, this novel strategy combines RTP of Mn-doped ZnS QDs with ATRP to use the best aspects of both. It offers the advantages of straightforward preparation and processing, fast response, low toxicity and optical stability, so it is very promising for the detection of bifenthrin.
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