Herein, a novel colorimetric aptasensor was introduced for detection of cocaine based on the formation of three-way junction pockets on the surfaces of gold nanoparticles (AuNPs) and the catalytic activity of the surfaces of AuNPs. Simplicity and detection of cocaine in a short time (only 35 min) are some of the unique features of the proposed sensing strategy. In the presence of cocaine, triple-fragment aptamer (TFA) forms on the surfaces of AuNPs, leading to a significant decrease of the catalytic activity of AuNPs and the color of samples remains yellow. In the absence of target, TFA does not form on the surfaces of AuNPs and 4-Nitrophenol, as a colorimetric agent, has more access to the surfaces of AuNPs, resulting in the reduction of 4-Nitrophenol and the color of sample changes from yellow to colorless. The sensing strategy showed good specificity, a limit of detection (LOD) of 440 pM and a dynamic range over 2-100 nM. The sensing method was also successfully applied to detect cocaine in spiked human serum samples with recovery of 94.71-98.63%.

中文翻译：

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基于在金纳米粒子表面形成三通连接袋的新型比色适体传感器用于超灵敏检测可卡因

在此，基于金纳米粒子 (AuNPs) 表面三路连接袋的形成和 AuNPs 表面的催化活性，引入了一种新型比色适体传感器来检测可卡因。在短时间内（仅 35 分钟）检测可卡因的简单性和检测是所提出的传感策略的一些独特之处。在可卡因存在下，AuNPs 表面形成三片段适体（TFA），导致 AuNPs 的催化活性显着降低，样品颜色保持黄色。在没有target的情况下，TFA不会在AuNPs表面形成，4-Nitrophenol作为比色剂，更接近AuNPs表面，导致4-Nitrophenol减少，样品颜色由黄色变为黄色到无色。传感策略显示出良好的特异性、440 pM 的检测限 (LOD) 和超过 2-100 nM 的动态范围。该传感方法还成功应用于检测加标人血清样品中的可卡因，回收率为 94.71-98.63%。