Zhang Cuiping, Lin Bixia, Cao Yujuan, Guo Manli, Yu Ying
School of Chemistry and Environment, Guangzhou Key Laboratory of Analytical Chemistry for Biomedicine, South China Normal University , Guangzhou 510006, P. R. China.
J Agric Food Chem. 2017 Apr 12;65(14):3065-3073. doi: 10.1021/acs.jafc.7b00166. Epub 2017 Apr 3.
Omethoate is a frequently used organophosphorus pesticide, and the establishment of a sensitive, selective, and simple method to determine omethoate is very important for food safety. In this paper, a dual strategy was applied to improve the detection sensitivity of omethoate. In the first strategy, graphene quantum dots (GQDs) were doped with nitrogen to increase the fluorescence quantum yield to 30%. By coupling N-GQDs with omethoate aptamer, an N-GQDs-aptamer probe was synthesized. The fluorescence of the N-GQDs-aptamer probe was turned off by graphene oxide (GO), but recovered by omethoate. Based on this principle, the fluorescence method for detecting omethoate was established with a detection limit of 0.041 nM. To further improve the detection sensitivity, the fluorescence polarization analysis method was applied as another strategy based on the polarization signal of GQDs. The detection limit was decreased to 0.029 pM by using the fluorescence polarization method. The detection limits in this paper were lower than those in other reports. The imaging of omethoate on plant leaves showed that the probe could be used for visual semiquantitative determination of omethoate.
氧乐果是一种常用的有机磷农药，建立一种灵敏、选择性好且简便的氧乐果测定方法对于食品安全至关重要。本文采用双重策略提高氧乐果的检测灵敏度。在第一种策略中，对石墨烯量子点（GQDs）进行氮掺杂，使其荧光量子产率提高到30%。通过将氮掺杂石墨烯量子点（N-GQDs）与氧乐果适配体偶联，合成了一种N-GQDs-适配体探针。该探针的荧光被氧化石墨烯（GO）淬灭，但可被氧乐果恢复。基于此原理，建立了检测氧乐果的荧光方法，检测限为0.041 nM。为进一步提高检测灵敏度，基于石墨烯量子点的偏振信号，采用荧光偏振分析方法作为另一种策略。采用荧光偏振法时，检测限降至0.029 pM。本文的检测限低于其他报道。氧乐果在植物叶片上的成像表明，该探针可用于氧乐果的可视化半定量测定。
