合成了一种新型的三维(3D)多孔氮-硫共掺杂碳(N-S-C)网格,并首次将其用作猝灭材料,构建了用于曲霉毒素A(OTA)检测的荧光传感器。通过使用cDNA作为启动子触发杂交链反应(HCR),开发了具有无酶信号扩增策略的荧光aptasensor,这有效地提高了这种aptasensor的灵敏度。在没有OTA的情况下,3D多孔N-S-C网可以吸附羧基荧光素FAM标记的发夹DNA1(H1-FAM)和发夹DNA2(H2),并猝灭FAM的荧光。在OTA面前,OTA特异性结合适体链并且DNA双链体经历解离。释放的cDNA又充当HCR的启动子,H1-FAM和H2的链组装由启动子触发,通过HCR产生长链DNA聚合物,导致荧光信号增加。在最优条件下,lgCOTA与荧光强度差异在0.01-500ng/mL范围内呈良好的线性关系(R2=0.993),检出限为2.7pg/mL。所设计的传感器平台用于测定花生中的加标OTA,小麦粉,玉米粉,红茶,和葡萄酒的回收率在94.4-119.6%之间。
A novel three-dimensional (3D) porous nitrogen-sulfur co-doped carbon (N-S-C) mesh was synthesized and used for the first time as the quenching material to construct a fluorescent aptasensor for ochratoxin A (OTA) detection. The fluorescent aptasensor with enzyme-free signal amplification strategy was developed by using cDNA as a promoter to trigger hybridization chain reaction (
HCR), which effectively improved the sensitivity of this aptasensor. In the absence of OTA, 3D porous N-S-C mesh can adsorb carboxyfluorescein FAM-labeled hairpin DNA1 (H1-FAM) and hairpin DNA2 (H2) and quench the fluorescence of FAM. In the presence of the OTA, the OTA specifically binds to the aptamer strand and the DNA duplex undergoes dissociation. The released cDNA in turn serves as a promoter for
HCR, and the strand assembly of H1-FAM and H2 is triggered by the promoter to generate long-strand DNA polymers via
HCR, resulting in an increasing fluorescent signal. Under optimal conditions, there was a good linear relationship between lgCOTA and fluorescence intensity difference in the range 0.01-500 ng/mL (R2 = 0.993), and the detection limit was 2.7 pg/mL. The designed sensor platform was applied to determine spiked OTA in peanut, wheat flour, corn flour, black tea, and wine with recoveries in the range of 94.4-119.6%.