基于DNA三向结构的电化学发光传感器对Hg^(2+)的高灵敏检测

Highly sensitive electrogenerated chemiluminescence detection of mercury(Ⅱ) based on three-way junction of DNA

利用T-Hg^(2+)-T碱基错配和Hg^(2+)诱导的DNA三向稳定结构,设计了一种高灵敏、高选择性的检测Hg^(2+)的信号增强型的电化学发光传感器。首先,将巯基化的捕获探针通过Au-S键自组装到预先处理干净的裸金电极表面,然后在此修饰电极上滴涂钌联吡啶衍生物标记的信号探针、辅助探针和Hg^(2+)的混和液,Hg^(2+)引起的T-Hg^(2+)-T碱基错配促使捕获探针、信号探针、辅助探针三条DNA链通过碱基配对形成了DNA三向结构,使电化学发光信号物质钌联吡啶衍生物固定在电极表面,从而产生电化学发光信号,以此为依据实现了对Hg^(2+)的高灵敏检测。在优化的实验条件下,增加的电化学发光峰值强度值与Hg^(2+)浓度的对数在1. 0×10-13～1. 0×10-8mol/L范围内呈良好的线性关系,检出限为5. 0×10-14mol/L。

A novel electrogenerated chemiluminescence （ECL） biosensor for highly sensitive and selective detection of mercury ion （ Hg2 ＋ ） in aqueous media has been developed. The method takes advantages of the highly selective thymine-Hg2＋-thymine （T-Hg2＋-T） coordination and the sensitive ＂signal-on＂ structure-switching three-way junction of DNA （DNA-TWJ）. The TWJ consisted of the capture probe that was self-assembled on the surface of a gold electrode through Au-S bond, the signal probe that was labeled with the ruthenium complex （ Rul ） and contained single T - T mismatch to capture probe, and an auxiliary probe for the formation of DNA-TWJ upon the presence of mercury （II）. This process caused the Rul tag approaching the electrode surface for fast electron transfer and thus increased the ECL intensity. The results showed that the increased ECL intensity was directly related to the logarithm of Hg2＋ concentrations in the range of 1.0 × 10 -13 mol/L to 1.0 × 10 -8moL/L, with a detection limit of 5.0 × 10 - 14 mol/L.