Department of Chemistry, National Central University Chungli County, Taoyuan City 32001 Taiwan, ROC.
Langmuir. 2022 Mar 1;38(8):2495-2501. doi: 10.1021/acs.langmuir.1c02943. Epub 2022 Feb 15.
The adsorption of nucleobase at a gold electrode has been a model system to study the interaction between biomolecule and metal, which is relevant to the development of sensors and molecular electronics. The current study has employed in situ scanning tunneling microscopy (STM) and voltammetry to investigate the adsorption configuration and spatial structure of guanine (G) on a well-defined Au(111) electrode in perchloric acid (HClO) and neutral phosphate buffer solution (PBS) containing 50 μM G. Potential control had a profound effect on the adsorption of the G molecule on the Au(111) electrode. No adsorption of G was observed at a potential more negative than 0 V in HClO and -0.2 V (versus Ag/AgCl) in PBS; shifting potential positively triggered a rapid adsorption of G to yield a well-ordered G array. Different spatial structures of G admolecules were imaged with STM in HClO and PBS, suggesting that ions in the electrolyte were important in this adsorption event. Shifting potential positively caused a more compact G adlayer with molecules adopting a tilted orientation. Meanwhile, G molecules continued to deposit on the Au(111) electrode leading to a multilayer G film. These processes were reversible to the potential modulation. G admolecules on the Au(111) electrode could be irreversibly oxidized in 0.1 M PBS, which resulted in a prominent peak at 0.74 V in the voltammogram. This oxidation process could be used to analyze the G molecule in a sample.
碱基在金电极上的吸附一直是研究生物分子与金属相互作用的模型体系，这与传感器和分子电子学的发展息息相关。本研究采用原位扫描隧道显微镜（STM）和伏安法，在高氯酸（HClO）和中性磷酸盐缓冲溶液（PBS）中，研究了浓度为 50 μM 的鸟嘌呤（G）在金电极上的吸附构象和空间结构。在 HClO 中，电位控制对 G 分子在 Au(111)电极上的吸附有很大的影响，电位比 0 V 更负时，G 分子不发生吸附；在 PBS 中，电位比-0.2 V（相对于 Ag/AgCl）更正时，G 分子迅速吸附，形成有序的 G 分子阵列。在 HClO 和 PBS 中，STM 可以成像不同空间结构的 G 分子，这表明电解质中的离子在吸附过程中起着重要作用。正移电位会导致 G 分子层更加紧密，分子呈倾斜取向。同时，G 分子继续在 Au(111)电极上沉积，形成多层 G 膜。这些过程可以通过电位调制来实现可逆性。在 0.1 M PBS 中，G 分子在 Au(111)电极上可以不可逆地被氧化，这导致在伏安图中出现 0.74 V 的明显峰值。这个氧化过程可用于分析样品中的 G 分子。
