Department of Chemistry, Seoul National University, Seoul 151-747, South Korea.
Analyst. 2009 Sep;134(9):1857-62. doi: 10.1039/b908457f. Epub 2009 Jun 25.
We have developed a selective, sensitive, and re-usable electrochemical sensor for Hg2+ ion detection. This sensor is based on the Hg2+-induced conformational change of a single-stranded DNA (ssDNA) which involves an electroactive, ferrocene-labeled DNA hairpin structure and provides strategically the selective binding of a thymine-thymine mismatch for the Hg2+ ion. The ferrocene-labeled DNA is self-assembled through S-Au bonding on a polycrystalline gold electrode surface and the surface blocked with 3-mercapto-1-propanol to form a mixed monolayer. The modified electrode showed a voltammetric signal due to a one-step redox reaction of the surface-confined ferrocenyl moiety. The 'signal-on' upon mercury binding could be attributed to a change in the conformation of ferrocene-labeled DNA from an open structure to a restricted hairpin structure. The differential pulse voltammetry (DPV) of the modified electrode showed a linear response of the ferrocene oxidation signal with increase of Hg2+ concentration in the range between 0.1 and 2 microM with a detection limit of 0.1 microM. The molecular beacon mercury(II) ion sensor was amenable to regeneration by simply unfolding the ferrocene-labeled DNA in 10 microM cysteine, and could be regenerated with no loss in signal gain upon subsequent mercury(II) ion binding.
我们开发了一种用于 Hg2+离子检测的选择性、灵敏性和可重复使用的电化学传感器。该传感器基于单链 DNA（ssDNA）的 Hg2+诱导构象变化，涉及电活性、标记有二茂铁的 DNA 发夹结构，并为 Hg2+离子提供了胸腺嘧啶-胸腺嘧啶错配的选择性结合。标记有二茂铁的 DNA 通过 S-Au 键自组装在多晶金电极表面上，并通过 3-巯基-1-丙醇进行表面封闭以形成混合单层。修饰电极由于表面受限的二茂铁部分的一步氧化还原反应而显示出伏安信号。Hg 结合后的“信号开启”可归因于标记有二茂铁的 DNA 构象从开放结构到受限发夹结构的变化。修饰电极的差分脉冲伏安法（DPV）显示，随着 Hg2+浓度在 0.1 至 2 microM 范围内的增加，二茂铁氧化信号呈线性响应，检测限为 0.1 microM。分子信标汞（II）离子传感器可通过简单地在 10 microM 半胱氨酸中展开标记有二茂铁的 DNA 进行再生，并且在随后结合 Hg（II）离子后可以再生，而不会损失信号增益。
