School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, 210093, China.
Analyst. 2012 Apr 7;137(7):1680-91. doi: 10.1039/c2an15716k. Epub 2012 Feb 17.
In this article we investigate the effect of monovalent cations (Li(+), Na(+), K(+), Cs(+)) on self-assembly of thiol-modified double-stranded DNA (ds-DNA) and single-stranded DNA (ss-DNA) on gold electrodes. Electrochemical characteristics (surface coverage, ion penetration and charge transfer) of ds-DNA and ss-DNA self-assembled monolayers (SAMs) formed with different monovalent cations are inspected based on six important interfacial parameters including surface coverage (Γ(m)), interfacial capacitance (C), phase angle (Φ(1 Hz)), ion transfer resistance (R(it)), current density difference (Δj) and charge transfer resistance (R(ct)) from chronocoulometry (CC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Three sections are included: (1) Investigation of the relationships of parameters (Γ(m), C, Φ(1 Hz), R(it), Δj and R(ct)) for ds-DNA-SAMs and ss-DNA-SAMs with cation types and concentrations; (2) confirmation and explanation of our experimental results combined with our recently proposed simple DNA model and literature reports; (3) exploration of the mechanism for the orders of monovalent cations (Li(+), Na(+), K(+), Cs(+)) on availing the adsorption of ds-DNA and ss-DNA molecules on gold based on their physicochemical parameters (ion size, solvation free energy and enthalpy, ion-water bond length and water exchange rate) and possible binding modes with DNA molecules. This work might provide a useful reference for understanding interactional mechanism of cations with DNA molecules.
在本文中，我们研究了单价阳离子（Li(+)、Na(+)、K(+)、Cs(+)）对巯基修饰的双链 DNA（ds-DNA）和单链 DNA（ss-DNA）在金电极上自组装的影响。基于包括表面覆盖率（Γ(m)）、界面电容（C）、相位角（Φ(1 Hz)）、离子转移电阻（R(it)）、电流密度差（Δj）和电荷转移电阻（R(ct)）在内的六个重要界面参数，检查了用不同单价阳离子形成的 ds-DNA 和 ss-DNA 自组装单层（SAM）的电化学特性（表面覆盖率、离子渗透和电荷转移）。本文包括三个部分：（1）研究参数（Γ(m)、C、Φ(1 Hz)、R(it)、Δj 和 R(ct)）与阳离子类型和浓度的关系；（2）结合我们最近提出的简单 DNA 模型和文献报道，对实验结果进行确认和解释；（3）根据单价阳离子（Li(+)、Na(+)、K(+)、Cs(+)）的物理化学参数（离子大小、溶剂化自由能和焓、离子-水键长和水交换率）和与 DNA 分子的可能结合模式，探索阳离子在促进 ds-DNA 和 ss-DNA 分子在金上吸附的顺序的机制。这项工作可能为理解阳离子与 DNA 分子的相互作用机制提供有用的参考。
