Ochratoxin A (OTA) is a hazardous food contaminant with significant health risks. Dual-channel OTA detection is noted for its cross-reference capability and high accuracy. Still, challenges in addressing in-system corrections and “signal off” related false positives and limited signal gains remain. Herein, we developed a dual-channel “signal on” aptasensor with one recognition process and two independent signal outputs for OTA analysis. The OTA aptamer binds to magnetic beads (MBs) and partially hybridizes with a complementary-trigger (cDNA-Trigger) sequence. Adding OTA disrupts the duplex sequence, leading to G-quadruplex (G4) formation and enrichment on the MBs, which then interacts with hemin to catalyze a color signal. Concurrently, the freed cDNA-Trigger catalyzes an enzyme-free DNA circuit, producing a fluorescence signal. The magnetic enrichment and signal amplification strategies make the proposed assay demonstrate excellent sensitivity toward OTA, with limits of detection (LOD) of 0.017 pM in the fluorescence channel and 48.1 pM in the colorimetric channel. Both channels have effectively detected OTA in grape juice and baijiu, demonstrating their applicability and reliability. Moreover, given the widespread use of smartphones globally, a mini-program with a self-correction function was designed to facilitate on-site colorimetric channel monitoring, making OTA detection more accessible and user-friendly.

中文翻译：

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比色和荧光独立的双“信号开启”生物传感器，用于基于适体触发的生物催化反应准确检测赭曲霉毒素 A

赭曲霉毒素 A (OTA) 是一种有害食品污染物，具有重大健康风险。双通道 OTA 检测以其交叉引用能力和高精度而闻名。尽管如此，解决系统内校正和“信号关闭”相关误报和有限信号增益的挑战仍然存在。在此，我们开发了一种双通道“信号开启”适体传感器，具有一个识别过程和两个独立的信号输出，用于 ​​OTA 分析。 OTA 适体与磁珠 (MB) 结合，并与互补触发 (cDNA-Trigger) 序列部分杂交。添加 OTA 会破坏双链体序列，导致 G-四链体 (G4) 形成并在 MB 上富集，然后与氯化血红素相互作用以催化颜色信号。同时，释放的 cDNA-Trigger 催化无酶 DNA 回路，产生荧光信号。磁性富集和信号放大策略使所提出的检测方法对 OTA 表现出优异的灵敏度，荧光通道中的检测限 (LOD) 为 0.017 pM，比色通道中的检测限为 48.1 pM。两个通道均已有效检测葡萄汁和白酒中的OTA，证明了其适用性和可靠性。此外，鉴于智能手机在全球的广泛使用，设计了具有自校正功能的小程序，以方便现场比色通道监控，使OTA检测更加便捷和人性化。