Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University.
Anal Sci. 2021 Jun 10;37(6):833-838. doi: 10.2116/analsci.20P306. Epub 2020 Oct 9.
A fluorometric aptasensor based on Escherichia coli O157:H7 (E. coli O157:H7) aptamer labeled aminated carbon quantum dots (NH-CQDs) and graphene oxide (GO) for the determination of E. coli O157:H7 was developed. In this research, carboxyl group (-COOH) terminated E. coli O157:H7 aptamer was steadily labeled to NH-CQDs by amidation reaction, and played the role of energy donor and was responsible for chemical recognition. Correspondingly, GO served as an energy acceptor. The introduction of NH-CQDs not only made the aptamer bond stably through covalent bond, but also significantly enhanced the fluorescence intensity compared with general CQDs. The NH-CQDs-aptamer is adsorbed on the surface of GO through π-π stacking and hydrophobic interaction. The fluorescence of NH-CQDs-aptamer was quenched via fluorescence resonance energy transfer (FRET) between NH-CQDs and GO. After adding E. coli O157:H7, the specific binding affinity between NH-CQDs-aptamer and E. coli O157:H7 lead to desorption of NH-CQDs-aptamer from GO, and recovery of the fluorescence intensity of NH-CQDs-aptamer. Under the optimal conditions, the increased fluorescence intensity showed a good linear relationship to concentrations of E. coli O157:H7 in the range 10 - 10 cells/mL, with a detection limit of 89 cells/mL. Furthermore, the developed method was successfully applied to the determination of E. coli O157:H7 in commercial milk samples.
基于大肠杆菌 O157:H7（E. coli O157:H7）适配体标记的氨基化碳量子点（NH-CQDs）和氧化石墨烯（GO）的荧光适配体传感器用于测定大肠杆菌 O157:H7。在这项研究中，通过酰胺反应将羧基（-COOH）末端的大肠杆菌 O157:H7 适配体稳定标记到 NH-CQDs 上，其充当能量供体并负责化学识别。相应地，GO 充当能量受体。引入 NH-CQDs 不仅通过共价键使适配体键合稳定，而且与普通 CQDs 相比，还显著增强了荧光强度。NH-CQDs-aptamer 通过π-π堆积和疏水相互作用吸附在 GO 表面上。NH-CQDs-aptamer 的荧光通过 NH-CQDs 和 GO 之间的荧光共振能量转移（FRET）被猝灭。加入大肠杆菌 O157:H7 后，NH-CQDs-aptamer 与大肠杆菌 O157:H7 之间的特异性结合亲和力导致 NH-CQDs-aptamer 从 GO 上解吸，并恢复 NH-CQDs-aptamer 的荧光强度。在最佳条件下，增加的荧光强度与 10 - 10 细胞/mL 范围内大肠杆菌 O157:H7 的浓度呈良好的线性关系，检测限为 89 个细胞/mL。此外，该方法成功应用于商业牛奶样品中大肠杆菌 O157:H7 的测定。
