Huang Yi-Ting, Chen Jia-Yin, Hsieh Chiao-An, Ezhumalai Yamuna, Huang Chun-Jen, Yau Shuehlin
Department of Chemistry, National Central University, Chungli County, Taoyuan City 32049, Taiwan ROC.
Department of Chemical and Materials Engineering, National Central University, Chungli County, Taoyuan City 32049, Taiwan ROC.
ACS Omega. 2024 Sep 10;9(38):39827-39835. doi: 10.1021/acsomega.4c05080. eCollection 2024 Sep 24.
11-acryloylamino undecanoic acid (AAUA) is a versatile polymerizable surfactant that has been applied to coat medical devices, and these applications can benefit from a fundamental understanding of its interaction with a metal substrate. Cyclic voltammetry and scanning tunneling microscopy (STM) were used to examine the adsorption configuration of AAUA molecules on an ordered Au(111) electrode and their mutual interactions, as AAUA was adsorbed from a methanol dosing solution. In addition to the van der Waals force between the aliphatic groups, the hydrogen bonding between the carboxylic acid and acrylamide groups was also important to guide the spatial arrangement of AAUA admolecules on the Au electrode. The -COOH group of AAUA admolecule likely dissociated in neutral media to -COO, which formed hydrogen bonds with HPO in phosphate buffer solution (PBS). This interaction between the AAUA admolecules and ions in the electrolyte resulted in different electrochemical characteristics observed in phosphate buffer solution (PBS) and potassium sulfate (KSO). Molecular-resolution STM imaging revealed distinctly different AAUA spatial structures on the Au electrode in PBS and KSO. Shifting the potential positively to 0.5 V (versus Ag/AgCl) led to lifting of the reconstructed Au(111) to the (1 × 1) phase and the dissolution of the ordered AAUA film, suggesting that the orientation of the AAUA admolecule was altered. The ordered AAUA adlayer could be partially recovered by shifting the potential negatively.
11-丙烯酰氨基十一烷酸（AAUA）是一种用途广泛的可聚合表面活性剂，已被应用于医疗设备涂层，而这些应用可受益于对其与金属基材相互作用的深入理解。采用循环伏安法和扫描隧道显微镜（STM）研究了AAUA分子从甲醇给药溶液中吸附到有序Au(111)电极上的吸附构型及其相互作用。除了脂肪族基团之间的范德华力外，羧酸基团和丙烯酰胺基团之间的氢键对于引导AAUA吸附分子在金电极上的空间排列也很重要。AAUA吸附分子的-COOH基团在中性介质中可能解离为-COO，其在磷酸盐缓冲溶液（PBS）中与HPO形成氢键。AAUA吸附分子与电解质中离子之间的这种相互作用导致在磷酸盐缓冲溶液（PBS）和硫酸钾（KSO）中观察到不同的电化学特性。分子分辨率STM成像揭示了在PBS和KSO中Au电极上明显不同的AAUA空间结构。将电位正向移动到0.5 V（相对于Ag/AgCl）导致重构的Au(111)转变为(1×1)相并使有序的AAUA膜溶解，这表明AAUA吸附分子的取向发生了改变。通过将电位负向移动，有序的AAUA吸附层可以部分恢复。
