Background

Ochratoxin A (OTA) is a serious food contaminant, not easily degradable, and capable of causing irreversible damage to the human body. Therefore, it is of great practical significance to establish a sensitive and efficient OTA detection method. The electrochemical aptasensor has a broad development prospect in OTA detection with its advantages of fast response speed and low cost.

Results

Herein, a cascade signal amplification strategy based on AuPt NPs/Zr-MOF and π-structure bipedal DNA walker-triggered hybridization chain reaction (HCR) was designed for the detection of ochratoxin A (OTA). AuPt NPs/Zr-MOF was employed as the electrode modification material, providing a large number of active sites and high conductivity, achieving 1.47 times signal amplification. Interestingly, bipedal DNA walker binds to hairpin 1 (H1) to form the π-structure. Under the activation of Pb²⁺, one bipedal DNA walker can simultaneously bind and cleave two H1. It exhibits a wide walking range and high recognition efficiency. After H1 is cleaved, the trigger sequence was exposed to trigger HCR and a large amount of methylene blue was loaded on the electrode. Under the optimal conditions, the linear range of the determined OTA is 1 × 10^-3 ∼ 500 ng/mL, and the limit of detection is as low as 0.525 pg/mL.

Significance

The experimental results demonstrate that the constructed electrochemical aptasensor is a sensitive and efficient platform for OTA monitoring. The applicability in food samples was also confirmed, and the strategy was efficiently selective and reproducible for different analytes. This provides ideas for subsequent food safety testing.

中文翻译：

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一种基于 π 结构双足 DNA walker 触发的杂交链式反应和 AuPt NPs/Zr-MOF 的无标记电化学传感器，用于 OTA 检测

 背景

赭曲霉毒素 A （OTA） 是一种严重的食品污染物，不易降解，能够对人体造成不可逆转的损害。因此，建立灵敏高效的 OTA 检测方法具有重要的现实意义。电化学适配体传感器具有响应速度快、成本低等优点，在OTA检测中具有广阔的发展前景。

 结果

在此，设计了一种基于 AuPt NPs/Zr-MOF 和 π 结构双足 DNA walker 触发的杂交链反应 （HCR） 的级联信号放大策略，用于检测赭曲霉毒素 A （OTA）。采用 AuPt NPs/Zr-MOF 作为电极改性材料，提供大量活性位点和高导电性，实现 1.47 倍的信号放大。有趣的是，双足 DNA walker 与发夹 1 （H1） 结合形成 π 结构。在 Pb²⁺ 激活下，一个双足 DNA 走动器可以同时结合和切割两个 H1。它表现出较宽的行走范围和高识别效率。H1 裂解后，触发序列暴露于触发 HCR，并在电极上加载大量亚甲蓝。在最佳条件下，测定的 OTA 的线性范围为 1 × ^10-3 ∼ 500 ng/mL，检测限低至 0.525 pg/mL。

 意义

实验结果表明，构建的电化学适配体传感器是一种灵敏高效的 OTA 监测平台。该策略在食品样品中的适用性也得到了证实，并且该策略对不同的分析物具有高效的选择性和重现性。这为后续的食品安全检测提供了思路。