In the present work, colloidal cerium oxide nanoparticles (nanoceria) and graphene quantum dots (GQDs) were firstly synthesized by sol-gel method and pyrolysis respectively, which all have a uniform nano-size and significant fluorescence emission. Due to the fluorescence emission spectrum of nanoceria overlapped the absorption spectrum of GQDs, fluorescence resonance energy transfer (FRET) between nanoceria and GQDs could occur effectively by the electrostatic interaction. Based on it, a sensitive ratiometric fluorescence aptasensor for the determination of ochratoxin A (OTA), a small molecular mycotoxin produced by Aspergillus and Penicillium strains, has been successfully constructed. In which, probe DNA1@nanoceria and DNA2@GQD were designed to complementary with OTA aptamer, both could adsorb each other, leading to the occur of FRET. After adding of OTA aptamer and then introducing of OTA, the FRET would be interrupted/recovered due to the specific affinity of OTA and its aptamer, the fluorescence recovery value would increase with the addition of OTA. Under the optimal experimental conditions (pH 7, mGQD/nanoceria 2, captamer 100 nM, incubation time 30 min), the constructed ratiometric fluorescence aptasensor exhibited a satisfying linear range (0.01-20 ng mL-1), low limit of detection (2.5 pg mL-1) and good selectivity towards OTA, and has been successfully applied for the analysis of real sample peanuts with good accuracy of the recoveries ranged from 90 to 110%.

中文翻译：

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用于测定赭曲霉毒素 A 的纳米氧化铈和石墨烯量子点之间的荧光共振能量转移适体传感器

在目前的工作中，胶体氧化铈纳米粒子（nanoceria）和石墨烯量子点（GQDs）首先分别通过溶胶-凝胶法和热解合成，它们都具有均匀的纳米尺寸和显着的荧光发射。由于纳米氧化铈的荧光发射光谱与 GQDs 的吸收光谱重叠，纳米氧化铈和 GQDs 之间的荧光共振能量转移 (FRET) 可以通过静电相互作用有效地发生。在此基础上，成功构建了一种用于测定赭曲霉毒素A（OTA）这一由曲霉属和青霉属菌株产生的小分子真菌毒素的灵敏比例荧光适体传感器。其中，探针 DNA1@nanoceria 和 DNA2@GQD 被设计为与 OTA 适配体互补，两者可以相互吸附，导致 FRET 的发生。添加OTA适配体后，再引入OTA，由于OTA与其适配体的特异性亲和力，FRET会被中断/恢复，荧光恢复值会随着OTA的加入而增加。在最佳实验条件下（pH 7，mGQD/nanoceria 2，captamer 100 nM，孵育时间30 min），构建的比率荧光适体传感器表现出令人满意的线性范围（0.01-20 ng mL-1），检测下限（2.5 pg mL-1) 和对 OTA 的良好选择性，并已成功应用于实际花生样品的分析，回收率准确度在 90% 到 110% 之间。