School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou, 215009, People's Republic of China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, People's Republic of China.
Mikrochim Acta. 2021 Mar 9;188(4):118. doi: 10.1007/s00604-020-04684-y.
Saxitoxin (STX) is a major marine toxin from shellfish, and it is responsible for paralytic shellfish poisoning (PSP). In this study, a highly sensitive and rapid aptamer assay was developed for STX detection by combining fluorescence resonance energy transfer (FRET) and nuclease-assisted target recycling signal amplification. The aptamer STX-41 conjugated with graphene quantum dots (GQDs) was adsorbed on magnetic reduced graphene oxide (MRGO) to establish a fluorescence quenching system. Then, the binding between STX and aptamer induced the desorption of GQD-aptamer from MRGO and the restoring of fluorescence for the fluorescent determination of STX. The digestion of the target bound aptamer by DNase I could release the target for recycling thus achieving signal amplification. Under the optimized conditions, the aptamer assay showed a wide detection range (0.1-100 ng·mL), low detection limit (LOD of 0.035 ng·mL), high specificity, good recovery (86.75-94.08% in STX-spiked clam samples) and repeatability (RSD of 4.27-7.34%). Combined with fluorescent detection technology, signal amplification technology, and magnetic separation technology, the proposed method can be used to detect STX in seafood products successfully.
石房蛤毒素（STX）是贝类中的一种主要海洋毒素，可引发麻痹性贝类中毒（PSP）。在本研究中，我们通过将荧光共振能量转移（FRET）与核酸酶辅助的靶标循环信号放大相结合，开发了一种用于 STX 检测的高灵敏度和快速适体分析方法。将与石墨烯量子点（GQDs）偶联的适体 STX-41 吸附在磁性还原氧化石墨烯（MRGO）上，以建立荧光猝灭系统。然后，STX 与适体之间的结合会诱导 GQD-适体从 MRGO 上解吸，并恢复荧光，从而实现对 STX 的荧光测定。DNase I 对结合靶标的适体的消化可以释放出靶标，从而实现信号放大。在优化条件下，适体分析表现出较宽的检测范围（0.1-100 ng·mL）、较低的检测限（LOD 为 0.035 ng·mL）、高特异性、良好的回收率（在贝类样本中 STX 加标回收率为 86.75-94.08%）和重现性（RSD 为 4.27-7.34%）。该方法结合荧光检测技术、信号放大技术和磁分离技术，可成功用于海产品中 STX 的检测。
