An Electrochemiluminescence Biosensor for the Determination of Mercury Ion via Dual-Amplification Strategy

A novel dual-signal amplificatory electrochemiluminescence (ECL) deoxyribonucleic acid (DNA) biosensor was designed for the determination of Hg2+. One amplification unit was gold nanoparticles (AuNPs) modified on a glassy carbon electrode, and the other was single-stranded DNA (ssDNA) (with amino at the 3’ terminal and thiol at the 5’ terminal) labeled with a carboxyl-functionalized Ru@SiO2 nanoparticles (Ru1@SiO2) as a nanoprobe. The ECL biosensor was obtained through a strong gold-sulfur bond between Au on AuNPs modified electrode and thiol in the nanoprobe. In the presence of Hg2+, the ECL signal reduced because the T-Hg2+-T existed between the ECL nanoprobe and the complementary DNA (c-DNA), which exhibited a sensing platform for the detection of Hg2+. The results revealed that the reduced ECL intensity was linearly proportional to the logarithm of the Hg2+ concentration in the range of 1.0 pmol L-1-100 nmol L-1 with limit of detection 0.02 pmol L-1. The proposed method was applied for the analysis of Hg2+ in the river water and the results were in good agreement with that obtained by atomic fluorescence spectroscopy.

本研究设计了一种新型双信号放大型电化学发光（electrochemiluminescence, ECL）脱氧核糖核酸（DNA）生物传感器，用于汞离子（Hg²+）的检测。该传感器包含两个放大单元：其一为修饰于玻碳电极表面的金纳米颗粒（AuNPs）；其二为以羧基功能化Ru@SiO₂纳米颗粒（Ru@SiO₂）标记的、3'端带氨基、5'端带巯基的单链DNA（ssDNA）纳米探针。通过修饰电极上AuNPs的金与纳米探针中巯基之间的强金硫键，制备得到该ECL生物传感器。当体系中存在Hg²+时，ECL信号会发生衰减，这是因为ECL纳米探针与互补DNA（c-DNA）之间会形成T-Hg²+-T特异性结合结构，由此构建出用于Hg²+检测的传感平台。实验结果表明，在1.0 pmol·L⁻¹~100 nmol·L⁻¹的浓度范围内，ECL强度的衰减值与Hg²+浓度的对数呈良好线性关系，检测限可达0.02 pmol·L⁻¹。将所提出的方法应用于河水中Hg²+的检测，所得结果与原子荧光光谱法的检测结果具有良好的一致性。