Abstract：
Development of a simple and convenient method for the rapid detection of organophosphorus pesticides (OPs) is particular important for the safety of environmental water and agriculture products. In this work, the water/liquid crystal (W/LC) emulsion is obtained via dispersing an aqueous solution of sodium dodecyl sulfate (SDS) and peroxidase from horseradish (HRP) into a water-immiscible nematic LC and employed as a sensing platform for the detection of dichlorvos (2, 2-dichlorovinyl dimethyl phosphate, DDVP) that is a typical OP with acute toxicity. Remarkably, the stepwise release of the encapsulated cargo HRP from the W/LC emulsion can be triggered upon the addition of the cationic surfactant myristoylcholine chloride (Myr) due to the strong interfacial charge interactions with the anionic surfactant SDS. The released HRP induces an obvious color change of the overlaying bulk aqueous solution via the H2O2-HRP-TMB reaction system. As Myr can be enzymatically cleaved by AChE, the detection of AChE is fulfilled successfully. This approach is also employed to detect DDVP that can irreversibly inhibit the activity of AChE. This assay shows a linear response between the absorbance of the oxidized TMB solution and the DDVP concentration in the range of 0.001-10 μg/mL (R2 = 0.99). The limit of detection (LOD) and the limit of quantity (LOQ) of DDVP are determined to be 1.9 ng/mL and 6.3 ng/mL, respectively. In addition, this strategy also demonstrates excellent performance for the DDVP detection in real samples, the detection recovery rate of DDVP in water samples (lake water and tap water) and vegetables (tomatoes and cole) by this method is 88.0 % ∼112.6 %, the relative standard deviation (RSD) ≤ 7.5 %. These results suggest the W/LC emulsion-based sensing platform shows great potential for visual detection of DDVP in real samples. In conclusion, the proposed approach is scalable for practical application in food safety as well as environmental monitoring fields, and will provide promising solutions for the assay of pesticide residues.
摘要：
开发一种简单方便的快速检测有机磷农药（OPs）的方法对于环境水和农产品的安全尤为重要。在这项工作中,水/液晶（W/LC）乳液是通过将十二烷基硫酸钠（SDS）和过氧化物酶的水溶液从辣根（HRP）分散到水不混溶的向列LC中获得的，并用作检测敌敌畏的传感平台（2，2-二氯乙烯基二甲基磷酸酯，DDVP）是一种典型的急性毒性OP。值得注意的是,由于与阴离子表面活性剂SDS的强界面电荷相互作用,在添加阳离子表面活性剂肉豆蔻酰胆碱氯化物(Myr)时,可以触发从W/LC乳液逐步释放包封的货物HRP。释放的HRP通过H2O2-HRP-TMB反应系统诱导覆盖的本体水溶液的明显颜色变化。由于Myr可以被AChE酶促裂解，AChE的检测成功完成。该方法还用于检测可以不可逆地抑制AChE活性的DDVP。该测定显示氧化的TMB溶液的吸光度与在0.001-10μg/mL(R2=0.99)范围内的DDVP浓度之间的线性响应。DDVP的检测限（LOD）和量限（LOQ）确定为1.9ng/mL和6.3ng/mL，分别。此外,这种策略也证明了在真实样品中DDVP检测的优异性能，该方法对水样(湖水和自来水)和蔬菜(番茄和油菜)中DDVP的检测回收率为88.0%~112.6%,相对标准偏差(RSD)≤7.5%。这些结果表明，基于W/LC乳液的传感平台在实际样品中显示出可视化检测DDVP的巨大潜力。总之,所提出的方法是可扩展的，适用于食品安全和环境监测领域的实际应用，并将为农药残留的测定提供有希望的解决方案。
