巯基修饰单链DNA在纳米金薄膜电极上自组装、杂交和取向的电化学交流阻抗谱

利用电化学交流阻抗技术对SH-ssDNA在纳米金薄膜电极表面的自组装、杂交和取向进行了系统表征。 探讨了SH-ssDNA的组装时间、浓度和链长对其自组装的影响，自组装15 h时电荷传递电阻Rct最大，表面覆盖率最高；研究了SH-ssDNA的浓度、链长以及与互补DNA的杂交方式对杂交反应的影响。 结果发现，随着单链浓度的增加，杂交后R_ct的变化值逐渐降低，当SH-ssDNA为5 μmol/L时Rct值比杂交前增加了16%。 通过对阻抗谱数据模拟和分析，表明SH-ssDNA以垂直竖立取向在金电极表面形成均匀致密单分子层，杂交效率与SH-ssDNA的覆盖率密切相关。

Electrochemical Impedance Spectroscopy Study of SH-ssDNA Self-Assembling, Hybridization and Orientation on Thin-film Nana-gold Electrode

The self-assembling， hybridization and orientation of SH-ssDNA on the surface of thin-film nano-gold electrodes were characterized systematically by means of the electrochemical impedance technique. The effects of assembling time, concentration and the length of SH-ssDNA on its self-assembling were investigated. The Rct and surface coverage reached the highest values when assembling time was 15 h. The influences of the concentration and length of SH-ssDNA and its hybridization method with complementary DNA on the hybridization reaction were also studied. The result shows the change of R_ct decreases with the increase of the SH-ssDNA concentration. The R_ct was increased by 16% when the concentration of SH-ssDNA was 5 μmol/L. The data simulation and analysis of impedance spectroscopy indicated that a unique self-assembled monolayer of SH-ssDNA was formed with an upright orientation on the nano-Au electrode surface. The result shows the hybridization efficiency is closely associated with the coverage of SH-ssDNA.