School of Food Science and Engineering, Foshan University, Foshan, 528000, China; Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangzhou, 510650, China.
School of Food Science and Engineering, Foshan University, Foshan, 528000, China.
Talanta. 2020 Jan 15;207:120258. doi: 10.1016/j.talanta.2019.120258. Epub 2019 Aug 14.
Utilizing G-quadruplex as the signal report probe, an ultrasensitive and label-free autocatalytic DNA circuit for Hg detection on the basis of exonuclease III (Exo III)-assisted cascade signal amplification has been proposed. In the absence of Hg, the hairpin A and the DNA1 cannot hybridize due to the thymine-thymine (T-T) mismatches. Therefore, hairpin probes with the 3'-protruding terminus can be resistant to Exo III digestion, preventing the G-rich sequence to be released. In the presence of Hg, the combination of the DNA1 with the 3' end-extruding hairpin A via T-Hg-T coordination chemistry triggers the digestion reaction of Exo III, leading to the release of the DNA1 and the sequence with domains c, d, and e. Both of the DNA1 and the sequence with domains c, d, and e can combine with other hairpin probes and activate another round of the cleavage reaction. The produced G-rich sequence can form G-quadruplex structure by binding with N-Methyl mesoporphyrin IX (NMM). The biosensor exhibits excellent selectivity and high sensitivity for Hg. The linear range of this biosensor is from 10 fM to 100 nM, and the linear equation can be expressed as: F = 1.3 × 10 Lg C + 7.40 × 10 (R = 0.998), in which F is the fluorescence intensity at 610 nm, C represents the Hg concentrations, and Lg is the logarithm of 10. The detection limit is 10 fM. The biosensor is robust and can be applied to the detection of Hg in water samples. By substituting the target-recognition elements, this sensing system can also be used for the detection of other metal ions.
利用 G-四链体作为信号报告探针，提出了一种基于外切酶 III（Exo III）辅助级联信号放大的超灵敏、无标记的自动催化 DNA 电路，用于 Hg 的检测。在没有 Hg 的情况下，发夹 A 和 DNA1 由于胸腺嘧啶-胸腺嘧啶（T-T）错配而不能杂交。因此，带有 3'-突出末端的发夹探针可以抵抗 Exo III 的消化，防止富含 G 的序列被释放。在存在 Hg 的情况下，DNA1 通过 T-Hg-T 配位化学与 3'端突出的发夹 A 结合，触发 Exo III 的消化反应，导致 DNA1 和具有域 c、d 和 e 的序列被释放。DNA1 和具有域 c、d 和 e 的序列都可以与其他发夹探针结合并激活另一轮切割反应。产生的富含 G 的序列可以通过与 N-甲基甲川卟啉 IX（NMM）结合形成 G-四链体结构。该生物传感器对 Hg 具有优异的选择性和高灵敏度。该生物传感器的线性范围为 10 fM 至 100 nM，线性方程可表示为：F = 1.3×10 Lg C + 7.40×10（R = 0.998），其中 F 是在 610 nm 处的荧光强度，C 代表 Hg 浓度，Lg 是 10 的对数。检测限为 10 fM。该生物传感器稳健且可用于水样中 Hg 的检测。通过替换靶识别元件，该传感系统还可用于其他金属离子的检测。
