Abstract This work presents the first comparative study on syntheses, characterization, and applications of different clay/gold nanoparticle composites (clay/AuNPs) as acetylcholinesterase (AChE) carriers and modified-electrode materials to detect chlorpyrifos, an organophosphate pesticide. The selected based-clays were plate-like kaolinite (Kaol; 1:1 aluminum phyllosilicate), globular montmorillonite (Mt; 2:1 aluminum phyllosilicate), globular bentonite (Bent; 2:1 aluminum phyllosilicate), and fibrous sepiolite (Sep; 2:1 inverted ribbons of magnesium phyllosilicate). The clay/AuNPs were synthesized using in situ chemical reduction of the gold precursor with anchoring 3-aminopropyl triethoxysilane (APTES) on the clay surfaces. The studied materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier transformed infrared (FTIR) spectroscopy, thermogravimetric analyzer (TGA), zeta-potential analysis, and electrochemical impedance spectroscopy (EIS). Surface area, surface charges, and hydrophilic/hydrophobic nature of based-clays and the clay/AuNPs played major roles on AChE loading, residual activity, and sensor storage stability. The Mt/AuNPs was determined, among the studied clays, as the best supports for AChE loading and residual activities due to its high specific surface area and weak electrostatic interaction with the immobilized enzyme. Since apparent catalytic efficiencies kcatapp/KMappof the immobilized AChE in the four clay/AuNPs were found statistically similar, Mt/AuNPs which contained the highest enzyme loading was the favorite modified-electrode material. For chlorpyrifos detection, Kaol/AuNPs-based sensors resulted in the lowest detection limit, presumably due to the strong hydrophobic surface that helps to concentrate the nonpolar pesticide to the vicinity of the immobilized enzyme. Unfortunately, the highest electrostatic repulsion between the Kaol/AuNPs and AChE, and the dehydrated Kaol surface resulted in the lowest storage stability of the AChE pesticide sensors. Overall, Mt/AuNPs showed the highest potential as the AChE carrier and the modified electrode material for chlorpyrifos determination.

中文翻译：

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粘土/金纳米颗粒复合材料作为乙酰胆碱酯酶载体和修饰电极材料：一项比较研究

摘要 这项工作首次比较研究了不同粘土/金纳米颗粒复合材料（粘土/金纳米粒子）作为乙酰胆碱酯酶 (AChE) 载体和修饰电极材料检测毒死蜱（一种有机磷农药）的合成、表征和应用。选定的基粘土为片状高岭石（Kaol；1:1 铝页硅酸盐）、球状蒙脱石（Mt；2:1 铝页硅酸盐）、球状膨润土（Bent；2:1 铝页硅酸盐）和纤维状海泡石（Sep； 2:1 的页硅酸镁倒置带）。粘土/AuNPs 是使用金前体的原位化学还原合成的，并将 3-氨基丙基三乙氧基硅烷 (APTES) 锚定在粘土表面。所研究的材料通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X 射线衍射 (XRD)、氮吸附/解吸、傅里叶变换红外 (FTIR) 光谱、热重分析仪 (TGA)、zeta 电位分析和电化学阻抗光谱 (EIS)。基粘土和粘土/AuNPs 的表面积、表面电荷和亲水/疏水性质对 AChE 负载、残留活性和传感器储存稳定性起着重要作用。在所研究的粘土中，Mt/AuNPs 被确定为 AChE 负载和残留活性的最佳支持物，因为它具有高比表面积和与固定化酶的弱静电相互作用。由于发现四种粘土/金纳米粒子中固定化 AChE 的表观催化效率 kcatapp/KMapp 在统计上相似，因此含有最高酶负载的 Mt/AuNPs 是最受欢迎的修饰电极材料。对于毒死蜱检测，基于 Kaol/AuNPs 的传感器产生最低检测限，大概是由于强疏水表面有助于将非极性农药集中到固定化酶附近。不幸的是，Kaol/AuNPs 和 AChE 之间的最高静电排斥以及脱水的 Kaol 表面导致 AChE 农药传感器的储存稳定性最低。总体而言，Mt/AuNPs 作为 AChE 载体和用于毒死蜱测定的修饰电极材料显示出最高的潜力。Kaol/AuNPs 和 AChE 之间的静电斥力最高，脱水的 Kaol 表面导致 AChE 农药传感器的储存稳定性最低。总体而言，Mt/AuNPs 作为 AChE 载体和用于毒死蜱测定的修饰电极材料显示出最高的潜力。Kaol/AuNPs 和 AChE 之间的静电斥力最高，脱水的 Kaol 表面导致 AChE 农药传感器的储存稳定性最低。总体而言，Mt/AuNPs 作为 AChE 载体和用于毒死蜱测定的修饰电极材料显示出最高的潜力。