Insights into electron tunneling across hydrogen-bonded base-pairs in complete molecular circuits for single-stranded DNA sequencing.
Insights into electron tunneling across hydrogen-bonded base-pairs in complete molecular circuits for single-stranded DNA sequencing.
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DOI：
10.1088/0953-8984/21/3/035110
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发表时间：
2009-01-21
期刊：
影响因子：
--
通讯作者：
Sankey OF
中科院分区：
文献类型：
--
作者：
Lee MH;Sankey OF
我们报告了通过包含连接到金属电极的脱氧胞苷一磷酸（dCMP）的分子结的电子弹道传输的第一原理研究。胍离子和鸟嘌呤核碱基被束缚在相对侧的金电极上，与 dCMP 分子形成氢键，从而提供电路。该电路模仿了一种潜在装置的组件，用于对未修饰的单链 DNA 进行测序。分子电导通过 DFT Green 函数散射方法获得，并与从复杂能带结构获得的电子隧道衰减常数的估计值进行比较。结果是，“连接子((CH2)2)-胍-磷酸-脱氧核糖-胞嘧啶-鸟嘌呤”的完整分子 dCMP 电路具有非常低的电导（fS 量级），而氢键鸟嘌呤-胞嘧啶碱基对具有中等电导（数十到数百 nS 量级）。因此，虽然通过碱基配对的横向电子转移具有适度的传导性，但通过完整的分子 dCMP 电路的电子转移则不然。发现金费米能级与鸟嘌呤-胞嘧啶碱基对和完整分子 dCMP 电路的 HOMO 非常接近。氢键 dCMP 分子的两种不同合理几何形状的结果表明，电导从延伸结构的 fS 到轻微压缩结构的 pS 变化。
We report a first-principles study of electron ballistic transport through a molecular junction containing deoxycytidine-monophosphate (dCMP) connected to metal electrodes. A guanidinium ion and guanine nucleobase are tethered to gold electrodes on opposite sides to form hydrogen bonds with the dCMP molecule providing an electric circuit. The circuit mimics a component of a potential device for sequencing unmodified single-stranded DNA. The molecular conductance is obtained from DFT Green’s function scattering methods and is compared to estimates from the electron tunneling decay constant obtained from the complex band structure. The result is that a complete molecular dCMP circuit of ‘linker((CH2)2)–guanidinium–phosphate–deoxyribose–cytosine–guanine’ has a very low conductance (of the order of fS) while the hydrogen-bonded guanine–cytosine base-pair has a moderate conductance (of the order of tens to hundreds of nS). Thus, while the transverse electron transfer through base-pairing is moderately conductive, electron transfer through a complete molecular dCMP circuit is not. The gold Fermi level is found to be aligned very close to the HOMO for both the guanine–cytosine base-pair and the complete molecular dCMP circuit. Results for two different plausible geometries of the hydrogen-bonded dCMP molecule reveal that the conductance varies from fS for an extended structure to pS for a slightly compressed structure.
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3.7
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