State Key Laboratory for Chemo/biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, PR China.
Biosens Bioelectron. 2010 Jan 15;25(5):1025-31. doi: 10.1016/j.bios.2009.09.017. Epub 2009 Sep 17.
A novel electrochemical sensor has been developed for sensitive and selective detection of mercury (II) based on target-induced structure-switching DNA. A 33-mer oligonucleotide 1 with five self-complementary base pairs separated by seven thymine-thymine mismatches was first immobilized on the electrode via self-assembly of the terminal thiol moiety and then hybridized with a ferrocene-tagged oligonucleotide 2, leading to a high redox current. In the presence of Hg(2+), mercury-mediated base pairs (T-Hg(2+)-T) induced the folding of the oligonucleotide 1 into a hairpin structure, resulting in the release of the ferrocene-tagged oligonucleotide 2 from the electrode surface with a substantially decreased redox current. The response characteristics of the sensor were thoroughly investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The effect of the reaction temperature on the response of the sensor was also studied in detail. The results revealed that the sensor showed sensitive response to Hg(2+) in a concentration range from 0.1 nM to 5 microM with a detection limit of 0.06 nM. In addition, this strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions, which was superior to that of previous anodic stripping voltammetry (ASV)-based techniques. The excellent sensitivity and selectivity signified the potential of the sensor for Hg(2+) detection in real environmental samples.
一种基于目标诱导结构转换 DNA 的新型电化学传感器已被开发用于灵敏和选择性检测汞（II）。首先，通过末端硫醇基团的自组装将具有五个自身互补碱基的 33 个碱基的寡核苷酸 1 固定在电极上，然后与带有二茂铁标记的寡核苷酸 2 杂交，导致高氧化还原电流。在存在 Hg(2+) 的情况下，汞介导的碱基（T-Hg(2+)-T）诱导寡核苷酸 1 折叠成发夹结构，导致带有二茂铁标记的寡核苷酸 2 从电极表面释放，氧化还原电流大大降低。使用循环伏安法（CV）、差分脉冲伏安法（DPV）和电化学阻抗谱（EIS）彻底研究了传感器的响应特性。还详细研究了反应温度对传感器响应的影响。结果表明，该传感器在 0.1 nM 至 5 μM 的浓度范围内对 Hg(2+)表现出灵敏的响应，检测限为 0.06 nM。此外，与先前基于阳极溶出伏安法（ASV）的技术相比，该策略对 Hg(2+)具有出色的选择性。出色的灵敏度和选择性表明该传感器在实际环境样品中检测 Hg(2+)的潜力。
