Zhang Jiaxin, Ma Xian, Chen Wenhua, Bai Yifan, Xue Pengli, Chen Kehan, Chen Wang, Bian Liujiao
College of Life Science, Northwest University, Xi'an, 710069, Shaanxi, China.
College of Life Science and Technology, Shaanxi University of Technology, Hanzhong, 723001, Shaanxi, China.
Anal Chim Acta. 2021 Mar 22;1151:338258. doi: 10.1016/j.aca.2021.338258. Epub 2021 Jan 30.
A novel bifunctional oligonucleotide (OND) probe with single fluorescent group HEX labelled at 5'-end was designed for detecting trace Ag(I) and Pb(II) in real samples. In the presence of Ag(I), the hairpin structure originating from Ag(I) induced cytosine-Ag(I)-cytosine mismatches causes the proximity of the HEX to the consecutive guanine bases (G) at 3'-terminal, resulting in the fluorescence quenching of the HEX. While in the presence of Pb(II), the G-quadruplex structure originating from two G-quartet planes by the intramolecular hydrogen bond with Pb(II) also causes the HEX approaching the (G) terminal and consequently the fluorescence quenching. The results showed the quantitative detection of trace Ag(I) and Pb(II) both in the linear response ranges of 1.0-20.0 × 10 mol L with no visible interferences of other 11 metal ions observed. And the detection limits were 82 × 10 mol L for Ag(I), 92 × 10 mol L for Pb(II), respectively. The fluorescence quenching mechanism of the (G) to HEX was verified to be the photoinduced electron transfer in the aspect of thermodynamics. This method provided a feasible application for sensitive and selective detection of Pb(II) and Ag(I) in water and Chinese traditional herbs with convenient operation.
设计了一种新型双功能寡核苷酸（OND）探针，其5'-端标记有单个荧光基团HEX，用于检测实际样品中的痕量Ag(I)和Pb(II)。在Ag(I)存在下，由Ag(I)诱导的胞嘧啶-Ag(I)-胞嘧啶错配产生的发夹结构使HEX靠近3'-末端的连续鸟嘌呤碱基（G），导致HEX荧光猝灭。而在Pb(II)存在下，由与Pb(II)的分子内氢键形成的两个G-四重平面产生的G-四链体结构也使HEX靠近（G）末端，从而导致荧光猝灭。结果表明，在1.0-20.0×10⁻⁶mol/L的线性响应范围内，痕量Ag(I)和Pb(II)均可进行定量检测，未观察到其他11种金属离子的明显干扰。Ag(I)的检测限为82×10⁻⁹mol/L，Pb(II)的检测限为92×10⁻⁹mol/L。从热力学角度验证了（G）对HEX的荧光猝灭机制为光诱导电子转移。该方法为水和中药中Pb(II)和Ag(I)的灵敏选择性检测提供了一种可行的应用，操作简便。
