摘要：食品安全逐渐成为社会的热点问题并受到越来越多的人们关注，其中赭曲霉毒素A（OTA）是由青霉属菌和曲霉属菌产生的一种主要真菌毒素，它存在于多种食品和食物链中并对其产生污染，比如谷物、咖啡、可可豆、调料、啤酒、红酒、葡萄汁和干果等。因此人们迫切地需要发展新颖、快速、高灵敏和可靠的分析方法对一些重要的真菌毒素进行检测。本论文提出了一种基于激子-等离子体激元相互作用（EPI）的新型光电化学适配体传感的制备方法，实现了赭曲霉毒素A的高灵敏度检测。为了构建该光电化学分析平台，我们通过逐步修饰分别制备了CdS/ITO电极、DNA/CdS/ITO电极和Au/aptamer-DNA/CdS/ITO电极，并使用扫描电镜对该修饰过程进行了表征。特别地，金纳米通过适配体和探针DNA杂交的方式桥接于CdS量子点表面并相隔合适的距离，从而激发激子-等离子体激元相互作用，随后CdS量子点的光电流因为发生能量转移而迅速降低。当加入目标物OTA后，目标物与适配体发生强相互作用，这一竞争反应使得适配体与探针DNA的杂交受到破坏，造成金纳米脱离电极表面，同时EPI能量转移系统发生改变，光电流迅速恢复。在最优化实验条件下，我们深入研究了光电流恢复值与目标物OTA浓度之间的关系，绘制标准曲线，线性范围为0.1pg/mL-100ng/mL，检测限可达到0.05pg/mL。该方法不仅为食品安全检测提供了一种高灵敏的检测手段，而且为食品安全管控提供了一个多样化的分析平台。

关键词：赭曲霉毒素A；光电化学；适配体传感器；激子-等离子体激元相互作用

Abstract：Food safety is nowadays a social hot spot and has become an increasingly serious problem which attracts more and more people’s attention. Ochratoxin A (OTA) represents a major mycotoxin produced by several species of the genera Aspergillus and Penicillium, it exists in and contaminates a variety of food products and food supply chains including cereals, coffee, cocoa, spices, beer, wine, grape juice, and dried fruits. Consequently, it is necessary and urgent to develop novel, fast, sensitive and reliable analytical methods to detect these specific mycotoxins. Herein, a new exciton-plasmon interactions (EPI) -based photoelectrochemical (PEC) aptasenor for ultrasensitive detection of OTA was fabricated. To construct this PEC platform, stepwise modification method was used to obtain the CdS/ITO, DNA/CdS/ITO, and Au/aptamer-DNA/CdS/ITO electrodes, which were also characterized by scanning electron microscopic (SEM). Specifically, Au nanoparticles (Au NPs) were bridged to CdS quantum dots (CdS QDs) for the stimulation of EPI by the hybridization of aptamer and probe DNA in this PEC system, the subsequent photocurrent of the CdS QDs would be greatly quenched via the energy transfer process when the interparticle distance had been adjusted to the appropriate range. In the presence of OTA, it could be captured by OTA aptamer to form complex, and then the hybridization between aptamer and probe DNA would be broken because of the competitive reaction of active sites, this result led to the detachment of Au NPs, the destruction of EPI-PEC system, and the recovery of photocurrent. So the relationship between the photocurrent recovering effect and the OTA concentration were deeply studied under the optimally experimental conditions, such as the layers of CdS QDs, the concentration of probe DNA, and the incubating time. The developed PEC platform displayed a linear range from 0.1 pg/mL - 100 ng/mL and the detection limit was experimentally found to be of 0.05 pg/mL. This work not only provided a highly sensitive PEC aptasensor but also offered a versatile platform for routine quality control of food safety.

Keywords: Ochratoxin A; Photoelectrochemistry; Aptasensor, Excition-Plasmon Interactions

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