A magnetic beads (MBs)–assisted fluorescence aptasensing approach based on dual DNA tweezers and magnetic separation was established for the detection of ochratoxin A (OTA) and fumonisin B₁ (FB₁). A dual DNA tweezers structure with four ends linked with fluorophores (FAM, ROX) and quenchers (BHQ₁, BHQ₂) was designed, and produced the high initial fluorescence signals because of the long spatial distance between FAM and BHQ₁, ROX, and BHQ₂. Bio-aptamer/anti-aptamer of OTA and bio-aptamer/anti-aptamer of FB₁ were respectively annealed to form dsDNA, and immobilized to MBs coated with streptavidin (SA). With the existence of OTA and FB₁, OTA and FB₁ preferentially bound with their respective bio-aptamers, which made anti-aptamers dissociate from dsDNA coupled on MBs. After magnetic separation, the dissociated anti-aptamers reacted with dual DNA tweezers, respectively, which made DNA tweezers close and the fluorescence was quenched. The linear ranges of approach for OTA and FB₁ detection were 0.05–20 ng/mL and 0.1–40 ng/mL, respectively. The limit of detection for OTA and FB₁ was 0.029 ng/mL and 0.061 ng/mL. The prepared MBs-assisted fluorescence aptasensing approach was applied to detect OTA and FB₁ in spiked red wine and corn samples, which showed good recoveries between 92 and 106%.

建立了一种基于双 DNA 镊子和磁分离的磁珠 (MB) 辅助荧光适配传感方法，用于检测赭曲霉毒素 A (OTA) 和伏马菌素 B ₁ (FB ₁ )。设计了一种双 DNA 镊子结构，其四个末端与荧光团（FAM、ROX）和猝灭剂（BHQ ₁、BHQ ₂）相连，由于 FAM 和 BHQ ₁、ROX 和 ROX之间的空间距离长，因此产生了高初始荧光信号总部₂ . OTA 的生物适体/抗适体和 FB _{1 的}生物适体/抗适体分别退火形成 dsDNA，并固定到涂有链霉亲和素 (SA) 的 MBs 上。随着OTA和FB ₁的存在, OTA 和 FB ₁优先与它们各自的生物适配体结合，这使得抗适配体与偶联在 MB 上的 dsDNA 分离。磁分离后，解离的抗适配体分别与双DNA镊子反应，使DNA镊子闭合，荧光猝灭。OTA 和 FB ₁检测方法的线性范围分别为 0.05-20 ng/mL 和 0.1-40 ng/mL。OTA 和 FB ₁的检测限为 0.029 ng/mL 和 0.061 ng/mL。制备的 MBs 辅助荧光适配传感方法用于检测加标红酒和玉米样品中的OTA 和 FB ₁，其回收率在 92% 到 106% 之间。