AbstractThe work describes a fluorescence-based study for mapping the highest affinity truncated aptamer from the full length sequence and its integration in a graphene oxide platform for the detection of Salmonella enteriditis. To identify the best truncated sequence, molecular beacons and a displacement assay design are applied. In the fluorescence displacement assay, the truncated aptamer was hybridized with fluorescein and quencher-labeled complementary sequences to form a fluorescence/quencher pair. In the presence of S. enteritidis, the aptamer dissociates from the complementary labeled oligonucleotides and thus, the fluorescein/quencher pair becomes physically separated. This leads to an increase in fluorescence intensity. One of the truncated aptamers identified has a 2-fold lower dissociation constant (3.2 nM) compared to its full length aptamer (6.3 nM). The truncated aptamer selected in this process was used to develop a fluorometric graphene oxide (GO) based assay. If fluorescein-labeled aptamer is adsorbed on GO via π stacking interaction, fluorescence is quenched. However, in the presence of target (S. enteriditis), the labeled aptamers is released from surface to form a stable complex with the bacteria and fluorescence is restored, depending on the quantity of bacteria being present. The resulting assay has an unsurpassed detection limit of 25 cfu·mL−1 in the best case. The cross reactivity to Salmonella typhimurium, Staphylococcus aureus and Escherichia coli is negligible. The assay was applied to analyze doped milk samples for and gave good recovery. Thus, we believe that the truncated aptamer/graphene oxide platform is a potential tool for the detection of S. Enteritidis. Graphical abstractFluorescently labelled aptamer against Salmonella enteritidis was adsorbed on the surface of graphene oxide by π-stacking interaction. This results in quenching of the fluorescence of the label. Addition of Salmonella enteritidis restores fluorescence, and this effect is used for quantification of this food-borne pathogen.

中文翻译：

---

使用截短的 DNA 适体基于荧光氧化石墨烯检测沙门氏菌肠炎

摘要这项工作描述了一项基于荧光的研究，用于从全长序列中绘制最高亲和力的截短适体，并将其整合到氧化石墨烯平台中，以检测肠炎沙门氏菌。为了确定最佳截断序列，应用了分子信标和置换分析设计。在荧光置换试验中，截短的适体与荧光素和淬灭剂标记的互补序列杂交，形成荧光/淬灭剂对。在肠炎沙门氏菌存在下，适体与互补的标记寡核苷酸分离，因此荧光素/猝灭剂对物理分离。这导致荧光强度增加。鉴定出的截短适体之一具有低 2 倍的解离常数 (3. 2 nM) 与其全长适体 (6.3 nM) 相比。在此过程中选择的截短适体用于开发基于荧光氧化石墨烯 (GO) 的测定。如果荧光素标记的适体通过 π 堆积相互作用吸附在 GO 上，荧光就会被淬灭。然而，在存在目标（肠炎沙门氏菌）的情况下，标记的适体从表面释放，与细菌形成稳定的复合物，荧光会恢复，具体取决于存在的细菌数量。在最佳情况下，所得到的检测具有无与伦比的检测限 25 cfu·mL-1。与鼠伤寒沙门氏菌、金黄色葡萄球菌和大肠杆菌的交叉反应性可以忽略不计。该测定用于分析掺杂的牛奶样品并得到良好的回收率。因此，我们相信截短的适体/氧化石墨烯平台是检测肠炎沙门氏菌的潜在工具。图形摘要针对肠炎沙门氏菌的荧光标记适体通过π-堆积相互作用吸附在氧化石墨烯表面。这导致标记的荧光猝灭。添加肠炎沙门氏菌可恢复荧光，这种效应可用于量化这种食源性病原体。