Herein, we propose rapid, precise acetylcholinesterase (AChE) inhibition-based sensing strategy for malathion detection in the presence of Ag-GO and acetylthiocholine (ATCh). The biosensing method was developed with a nanocomposite of citrate stabilized AgNPs anchored on the GO sheets (Ag-GO). The physical and chemical properties of the prepared Ag-GO composite were analyzed with various characterization techniques, including XRD, FT-IR, XPS, UV-Visible spectroscopy, and HR-TEM. The positively charged thiocholine (TCh) produced by enzyme hydrolysis triggers the AgNPs aggregation on GO sheets, which ultimately decreases the intensity of the corresponding SPR absorption peak. While the addition of malathion into the sensing system hindered the AChE activity and limited the TCh production, and thus inhibits the decrease in the SPR band intensity. The designed sensing system displayed linearity in the broad range of malathion concentrations (0.01 pM-1000 pM) with a limit of detection and the limit of quantification values of 0.01 pM, and 0.035 pM, respectively. The application of the designed biosensing system was extended to determine the malathion in actual samples namely, tap water, agricultural runoff water, lake water, and grape extract, which resulted in almost 100% recovery rates in all the spiked samples.

中文翻译：

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使用银纳米颗粒-氧化石墨烯 (Ag-GO) 纳米复合材料对马拉硫磷进行超灵敏和选择性的基于 AChE 的比色检测

在此，我们提出了一种快速、精确的基于乙酰胆碱酯酶 (AChE) 抑制的传感策略，用于在存在 Ag-GO 和乙酰硫代胆碱 (ATCh) 的情况下检测马拉硫磷。生物传感方法是用固定在 GO 片（Ag-GO）上的柠檬酸盐稳定的 AgNPs 纳米复合材料开发的。使用各种表征技术分析了制备的 Ag-GO 复合材料的物理和化学性质，包括 XRD、FT-IR、XPS、UV-可见光谱和 HR-TEM。酶水解产生的带正电荷的硫代胆碱 (TCh) 会触发 GO 片上的 AgNPs 聚集，最终降低相应 SPR 吸收峰的强度。而在传感系统中加入马拉硫磷会阻碍 AChE 活性并限制 TCh 的产生，从而抑制 SPR 带强度的降低。设计的传感系统在广泛的马拉硫磷浓度范围内（0.01 pM-1000 pM）显示线性，检测限和定量值分别为 0.01 pM 和 0.035 pM。将设计的生物传感系统的应用扩展到测定实际样品中的马拉硫磷，即自来水、农业径流水、湖水和葡萄提取物，使所有加标样品的回收率几乎达到 100%。