Mechanism of the counterion binding at soft interface controlled by ion hydration and interfacial curvature

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14507
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 28040:Nanobioscience-related
• Research Institution: Kyushu University
• Principal Investigator: Imai Yosuke 九州大学, 基幹教育院, 助教 (90738816)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 水溶液表面 / 多価対イオン / 水和

Outline of Final Research Achievements

The purpose of this research is to elucidate the molecular mechanism of counterion bonding to molecular assemblies with different curvatures formed by surfactants. The interaction between divalent cation Ca (2+) and sulfonate group (SO3-) were investigated by hydration structure analysis of Ca(2+) through total reflection, transmission, and fluorescence XAFS, for octylbenzenesulfonic acid adsorbed films (planar) and micelles (spherical). There was no significant difference in the shape of the XAFS spectra of Ca(2+) among adsorbed films, micelles,the bulk solution.Thus, the hydration structure of Ca ions on the micelle surface and adsorption film was similar to that in the bulk solution. These data are expected to verify previous theories such as the Collins law of counterion bonding.

Free Research Field

界面物理化学

Academic Significance and Societal Importance of the Research Achievements

界面の官能基と相互作用するCaなどの軽元素の多価イオンの水和構造については、配位数や配位距離などの構造パラメーターを実験的に定量した実験データがこれまでに報告されておらず、その方法論を確立した点に本申請課題の学術的意義がある。脂質細胞膜やDNAやたんぱく質などに対するCaイオンの効果など、生体分子へのイオン効果について、水和レベルから分子メカニズムを明らかにする応用研究の進展が期待される。