Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, Canada N6A 5B7.
Analyst. 2010 Sep;135(9):2280-5. doi: 10.1039/c0an00184h. Epub 2010 Jul 29.
Electrochemical impedance spectroscopy (EIS) has been used as an ultrasensitive tool for label-free detection of single-nucleotide mismatches in double-stranded DNA (ds-DNA) films. In this study, we have explored the effects of the position and of the type of single-nucleotide mismatch in ds-DNA on gold surfaces and were able to distinguish mismatch positions and mismatch pairs. The single-nucleotide mismatches A-C, A-A and A-G were introduced at three positions within the sequence in bottom, middle and top positions of ds-DNA, the films were studied by EIS, and the impedance results were interpreted with the help of equivalent circuits. The DeltaR(ct), the difference in charge transfer resistance before and after the addition of Zn(2+), was used to distinguish single-nucleotide mismatch within the DNA sequences. Importantly, the mismatch pair is easily distinguishable at the middle position. A purine-pyrimidine mismatch can be distinguished from purine-purine mismatch by its lower DeltaR(ct) value. In addition, all ds-DNA films were studied by scanning electrochemical microscopy in the absence and presence of Zn(2+), allowing us to distinguish a range of mismatched films from matched ds-DNA film.
电化学阻抗谱（EIS）已被用作一种超灵敏的工具，用于无标记检测双链 DNA（ds-DNA）薄膜中的单碱基错配。在这项研究中，我们探讨了单碱基错配在 ds-DNA 中的位置和类型对金表面的影响，并能够区分错配位置和错配对。在 ds-DNA 的底部、中部和顶部三个位置处的序列中引入了单碱基错配 A-C、A-A 和 A-G，通过 EIS 研究了这些薄膜，并借助等效电路解释了阻抗结果。通过添加 Zn(2+)前后的电荷转移电阻的差异（DeltaR(ct)），可以区分 DNA 序列中的单碱基错配。重要的是，在中间位置很容易区分错配对。嘌呤-嘧啶错配与嘌呤-嘌呤错配可以通过其较低的 DeltaR(ct) 值来区分。此外，还通过在有无 Zn(2+)的情况下对所有 ds-DNA 薄膜进行扫描电化学显微镜研究，使我们能够从匹配的 ds-DNA 薄膜中区分出一系列错配的薄膜。
