基于电化学寡核苷酸传感器的痕量汞离子检测

Trace Mercury Ions Detection Based on the Electrochemical Oligonucleotide Sensor

水环境中的重金属汞污染日益严重,对生态环境和人类健康造成了不容忽视的威胁。因此,现场监测痕量汞离子具有极其重要的意义。构建了一种基于胸腺嘧啶-Hg^2+-胸腺嘧啶(T-Hg^2+-T)特异性配位结构的无标记型电化学寡核苷酸传感器,用于检测痕量Hg^2+。将末端修饰巯基的富T寡核苷酸链(Oligo)自组装到金电极表面,当存在Hg^2+时,Oligo探针将捕获Hg^2+而发生构象变化,形成"发卡型"结构。利用电化学阻抗谱对金电极表面自组装膜的构象变化进行表征,发现电子转移阻抗RCT随Hg^2+浓度的升高而减小,建立两者间的线性关系,从而实现对Hg^2+的定量检测。本传感器在0.5 nmol/L^500 nmol/L范围内具有良好线性关系,检出限为0.2 nmol/L,特异性实验表明该传感器对Hg^2+选择性极好。该传感器为水环境中痕量汞离子的准确、定量检测提供了一种有效的手段。

The heavy metal pollution in aquatic environment is becoming daily serious,which poses a threat to the ecological environment and human health. Thus on-site monitoring of trace heavy metal ions is extremely important. An unlabeled electrochemical oligonucleotide sensor based on thymine-Hg^2+-thymidine(T-Hg^2+-T)specific coordination structure was constructed for the detection of trace Hg^2+. The T-rich oligonucleotide(Oligo)with a terminally modified thiol group was self-assembled onto the surface of the gold electrode. In the presence of Hg^2+,the Oligo will capture it and undergo a conformational change to form a hairpin type structure. The conformational change of self-assembled film on the surface of gold electrode was characterized by electrochemical impedance spectroscopy. It was found that the electron transfer impedance RCT decreased with the increase of Hg^2+ concentration,and the linear relationship between the two was established to realize the quantitative detection of Hg^2+. The sensor has a good linear relationship in the range of 0.5 nmol/L^500 nmol/L,and the detection limit is 0.2 nmol/L. The specific experiment also showed that the sensor had the excellent selectivity to Hg^2+.