College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China.
Anal Bioanal Chem. 2021 Jan;413(3):901-909. doi: 10.1007/s00216-020-03044-2. Epub 2020 Nov 12.
We developed a fluorescent aptamer/graphene oxide (GO)-based biosensor to detect sulfamethazine (SMZ) residues in animal-derived foods. The SMZ-bound aptamers were identified and screened with an improved GO-SELEX technique using non-immobilizing ssDNA library. After seven rounds of selection, six SMZ aptamers were sequenced and analyzed for secondary structure, and their affinity and specificity were assessed by binding assays. The truncated aptamer (SMZ1S: 5'-CGTTAGACG-3') with a unique stem-loop structure showed the highest affinity (K = 24.6 nM) to SMZ and was used to develop a GO-based fluorescent aptasensor. The binding mechanism between SMZ1S and SMZ was further analyzed by molecular docking. Under optimal conditions, the fluorescent aptasensor showed low detection limits (0.35 ng/mL) and a wide dynamic linear range (from 2 to 100 ng/mL). The aptasensor was also validated against real samples spiked with SMZ, which showed a fluorescence recovery from 93.9 to 108.8% and a coefficient of variation of < 12.7%. Taken together, these results suggest that this novel aptasensor can be used to sensitively, selectively, and accurately detect SMZ residues in foods. Schematic illustration of fluorescent aptasensor based on aptamer/graphene oxide complex detection of of SMZ.
我们开发了一种基于荧光适体/氧化石墨烯（GO）的生物传感器，用于检测动物源性食品中的磺胺甲恶唑（SMZ）残留。采用改进的 GO-SELEX 技术，使用非固定化的 ssDNA 文库，鉴定和筛选与 SMZ 结合的适体。经过七轮筛选，对六个 SMZ 适体进行测序和二级结构分析，并通过结合试验评估其亲和力和特异性。具有独特茎环结构的截断适体（SMZ1S：5'-CGTTAGACG-3'）对 SMZ 表现出最高的亲和力（K = 24.6 nM），并用于开发基于 GO 的荧光适体传感器。通过分子对接进一步分析了 SMZ1S 与 SMZ 之间的结合机制。在最佳条件下，荧光适体传感器的检测限低（0.35 ng/mL），动态线性范围宽（2-100 ng/mL）。该适体传感器还对添加 SMZ 的实际样品进行了验证，荧光恢复率为 93.9%至 108.8%，变异系数<12.7%。综上所述，这些结果表明，这种新型适体传感器可用于灵敏、选择性和准确地检测食品中的 SMZ 残留。基于适体/氧化石墨烯复合物检测磺胺甲恶唑的荧光适体传感器示意图。
