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_d = 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.

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二甲嘧啶（SMZ）残留。鉴定出SMZ结合的适体，并使用非固定的ssDNA文库用改良的GO-SELEX技术进行筛选。经过七轮选择，对六个SMZ适体进行了测序并分析了二级结构，并通过结合测定评估了它们的亲和力和特异性。具有独特茎环结构的截短适体（SMZ1S：5'-CGTTAGACG-3'）显示出最高的亲和力（K _d = 24.6 nM）到SMZ，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和SMZ之间的结合机理。在最佳条件下，荧光适体传感器显示出低检测限（0.35 ng / mL）和宽动态线性范围（2至100 ng / mL）。aptasensor还针对掺有SMZ的真实样品进行了验证，该样品的荧光回收率从93.9提高至108.8％，变异系数<12.7％。综上所述，这些结果表明，该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。