School of Health Science and Engineering, Shanghai Engineering Research Center for Food Rapid Detection, University of Shanghai for Science and Technology, Shanghai 200093, China.
School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou 215009, China.
J Agric Food Chem. 2022 Aug 31;70(34):10662-10668. doi: 10.1021/acs.jafc.2c03626. Epub 2022 Aug 8.
Ochratoxin A (OTA) contamination of corn has received significant attention due to the wide distribution and high toxicity of OTA. The maximum residue limit standard of OTA in corn has been established by the Chinese Government and other unions. Nanoparticle-based fluorescence resonance energy transfer (FRET) assays are promising methods for the sensitive and fast detection of OTA. However, satisfactory detection sensitivity is commonly achieved with complicated signal amplification processes or specific nanoparticle morphologies, which means that these assays are not conducive to fast detection. This study proposes a simple and novel strategy to improve the sensitivity of FRET aptasensors. In this strategy, a DNA tetrahedron was first used in gold nanorod-based FRET aptasensors. DNA tetrahedron-modified gold nanorods are used as fluorescent acceptors, and Cy5-modified complementary sequences of the OTA aptamer are used as fluorescent donors. The aptamers of OTA are embedded in the DNA tetrahedrons, and FRET occurs when the aptamers hybridize with the Cy5-modified complementary sequences. The aptamer-integrated DNA tetrahedron modified on the surface of gold nanorods acts as an anchor, thus avoiding the crowding and entanglement of aptamers. Due to the competitive combination between the OTA aptamers and complementary sequences, the greater the amount of OTA, the less the amount of Cy5-modified complementary sequences that bind with the aptamers and the less the amount of Cy5 that is quenched. Thus, the fluorescence intensity is positively related to the OTA concentration. In this study, in the concentration range of 0.01-10 ng/mL, the fluorescence intensity was found to be linearly related to the logarithmic concentration of OTA. The limit of detection was calculated to be 0.005 ng/mL. The specificity of the developed biosensor was demonstrated to be efficient. The accuracy and stability of the developed aptasensor were also tested, and the method exhibited good performance in real samples.
OTA（赭曲霉毒素 A）污染玉米受到了广泛关注，这是因为 OTA 分布广泛且毒性很强。中国政府和其他联盟已经制定了玉米中 OTA 的最大残留限量标准。基于纳米粒子的荧光共振能量转移（FRET）分析是一种很有前途的检测 OTA 的灵敏、快速的方法。然而，通常需要复杂的信号放大过程或特定的纳米粒子形态才能达到令人满意的检测灵敏度，这意味着这些分析方法不利于快速检测。本研究提出了一种简单而新颖的策略来提高 FRET 适体传感器的检测灵敏度。在该策略中，首先在基于金纳米棒的 FRET 适体传感器中使用了 DNA 四面体。DNA 四面体修饰的金纳米棒被用作荧光受体，而 OTA 适体的 Cy5 修饰互补序列被用作荧光供体。OTA 适体被嵌入到 DNA 四面体中，当适体与 Cy5 修饰的互补序列杂交时发生 FRET。金纳米棒表面修饰的整合有适体的 DNA 四面体作为一种锚定物，从而避免了适体的拥挤和缠结。由于 OTA 适体与互补序列之间的竞争结合，OTA 的量越大，与适体结合的 Cy5 修饰互补序列的量就越少，被猝灭的 Cy5 的量就越少。因此，荧光强度与 OTA 浓度呈正相关。在本研究中，在 0.01-10ng/mL 的浓度范围内，荧光强度与 OTA 的对数浓度呈线性关系。检测限计算为 0.005ng/mL。所开发的生物传感器的特异性被证明是有效的。还测试了所开发的适体传感器的准确性和稳定性，该方法在实际样品中表现出了良好的性能。
