We developed a highly sensitive and selective method for double-signal analysis (fluorescence and ultraviolet–visible spectrophotometry) of organophosphorus pesticides (OPs), based on reversible quenching of graphene quantum dots (GQDs; fluorophores) with silver nanoparticles (AgNPs; absorbers). We used acetylcholinesterase to catalytically convert acetylthiocholine into thiocholine. In turn, by competitive binding to the AgNPs, the produced thiocholine displaces AgNPs from the GQDs and thus induces fluorescence recovery. However, OP analytes inhibit the activity of acetylcholinesterase and, in so doing, retain the silver–graphene nanoparticle complex and fluorescence quenching. The degree of quenching is proportional to the concentration of OPs; the detection limit is as low as 0.017 μg/L. The ultraviolet–visible absorption of GQDs/AgNPs at 390 nm decreases—because of AgNP aggregation that occurs after desorption from the GQDs—and the absorbance is linearly proportional to the OP concentration. Our system has good selectivity to substances that are commonly present in water and vegetables. We successfully applied our method to OP analysis in water, apple, and carrot samples.

我们基于石墨烯量子点（GQD；荧光团）与银纳米颗粒（AgNP；吸收剂）的可逆猝灭，开发了一种高灵敏度和选择性的方法，用于有机磷农药（OP）的双信号分析（荧光和紫外可见分光光度法）。我们使用乙酰胆碱酯酶将乙酰基硫代胆碱催化转化为硫代胆碱。反过来，通过竞争性结合到AgNPs，产生的硫代胆碱从GQDs取代了AgNPs，从而诱导了荧光的恢复。但是，OP分析物会抑制乙酰胆碱酯酶的活性，并因此保留了银-石墨烯纳米颗粒复合物和荧光猝灭。淬灭程度与OP的浓度成正比。检出限低至0.017μg/ L。GQDs / AgNPs在390 nm处的紫外-可见光吸收减少-因为从GQDs解吸后发生AgNP聚集-吸光度与OP浓度成线性比例。我们的系统对水和蔬菜中常见的物质具有良好的选择性。我们成功地将我们的方法应用于水，苹果和胡萝卜样品中的OP分析。