基于T-T碱基错配的荧光传感器特异性检测汞离子

在本文中，我们研制了一种基于T-T碱基错配特异性键合汞离子的荧光传感器用于汞离子的检测。该传感器由两条分别标记了荧光基团（F）和淬灭基团（Q）的DNA探针组成，并且含有两对用于结合汞离子的T-T错配碱基。当汞离子存在时，两条探针之间形成T-Hg2+-T结构，作用力增强，从而拉近了荧光基团与淬灭基团之间的距离，发生能量转移，使荧光信号在一定程度上被淬灭。在优化的条件下，我们使用该传感器对汞离子进行检测，动力学响应范围为50nM到1000nM，线性相关方程为y= 5281.13 - 1650.56 lgHg2+] ( R2 = 0.985)，检测下限为79nM。此外，我们还考察了该传感器的选择性，当用其它干扰离子（浓度都为1.0µM）代替待测离子进行实验时，没有发生明显的荧光淬灭，说明该传感器具有较高的选择性。该传感器的构建为汞离子的检测提供了一条快速、简便的新途径。

An Oligonucleotide‐based Fluorescence Sensor for Mercury(II) in Aqueous Solutions

A highly selective fluorescence sensor was developed for Hg(II) ion detection in aqueous solutions based on the selective binding of Hg(II) ions with a pair of thymine‐thymine mismatch. The sensor consists of two DNA probes functionalized with a fluorophore (fluorescein, F) and a quencher (tetramethyl rhodamine, Q) moiety separately. This pair of DNA probes contains two pairs of thymine‐thymine mismatches used to detect Hg(II) ions. In the presence of Hg(II) ions, thymine‐Hg²⁺‐thymine was formed between thymine residues of probes. From that, the interaction of the two DNA probes increased. Thus, the DNA probes formed a double‐stranded structure. Both the fluorophore and quencher were brought close to each other leading to the fluorescence resonance energy transfer (FRET) between F and Q. Under the optimum conditions, the sensor was used to detect the Hg(II) ions from 50 to 1000 nmol·L^?1 with a regression equation y=5281.13?1650.56 lgHg²⁺] (R²=0.985). The linear range covers 100 to 500 nmol·L^?1, and the limit of detection (LOD) is 79 nmol·L^?1. The disturbance of some co‐existing metal ions was explored, and no significant fluorescence quenching in the presence of 1.0 μmol·L^?1 other metal ions was observed. The fluorescence sensor has good sensitivity and selectivity for Hg(II) ions providing a rapid, simple and low cost method for the detection of mercury(II) ions in aqueous solutions.