扫描电化学显微镜
单层
电化学
显微镜
离子
扫描隧道显微镜
化学
灵敏度(控制系统)
扫描探针显微镜
分析化学(期刊)
扫描离子电导显微镜
材料科学
纳米技术
化学工程
电极
色谱法
物理化学
扫描共焦电子显微镜
光学
有机化学
物理
工程类
电子工程
作者
Na Li,Ximing Huang,Huibo Shao
出处
期刊:Langmuir
[American Chemical Society]
日期:2023-04-28
卷期号:39 (18): 6529-6538
被引量:1
标识
DOI:10.1021/acs.langmuir.3c00469
摘要
Insights into the chemical essence of weak interactions on the surface of biomacromolecules may help to regulate biological processes. In this work, the pH sensitivity of ion-pair interactions occurring on a cysteine self-assembled monolayer (Cys SAM) that simulates the local surface of a protein was probed by scanning electrochemical microscopy (SECM). Cys SAM and the ion-pair interactions subsequently formed with the introduced aspartic acid (Asp) were both pH-sensitive, as confirmed by the tip current changes in the feedback mode. After continuous pH measurements, the most significant negative feedback was observed at pH 5.50, indicating the most robust ion-pair interactions, which were simultaneously identified by voltammetry. In this case, the extra addition of the inorganic cation (i.e., Ca2+) did not disrupt the existing ion-pair interactions, and the binding constant (K) and Gibbs free energy (ΔGo) of the ion pair were finally determined to be 6.44 × 105 M-1 and -33.14 kJ mol-1, respectively. Overall, the pH sensitivity of ion-pair interactions was found to be mainly attributable to pH-induced changes in the deprotonated/protonated states of the α-amino acid moieties, which may provide insights into the artificial manipulation of complex binding events at the molecular level on the biological surface.
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