Ishii Kosuke, Ueki Takeshi, Nakanishi Jun, Akutsu-Suyama Kazuhiro, Yamada Norifumi L, Yokoyama Yuko, Sakka Tetsuo, Nishi Naoya
Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510, Japan.
Research Center for Macromolecules & Biomaterials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Langmuir. 2025 Jul 15;41(27):17973-17981. doi: 10.1021/acs.langmuir.5c01819. Epub 2025 Jul 1.
Protein nanolayers (PNLs) formed at an electrochemical liquid|liquid interface between water (W) and a fluorous solvent (F) were examined by using interfacial rheological measurement (IRM) and neutron reflectometry (NR) under the externally controlled condition of the phase boundary potential differences (= φ - φ + const.), where F contained a hydrophobic ionic liquid (IL) as a supporting electrolyte and W, whose pH was 7.4, contained a protein, bovine serum albumin (BSA). The IRM and NR results illuminated that both static and dynamic properties of the PNL at the electrochemical F|W interface were varied by applying . NR found minimal dependence on the adsorption amount of BSA in the PNL. In contrast, IRM revealed that although the interfacial shear loss moduli ″ of the PNL was constant regardless of , the interfacial shear storage ' of the PNL increased dramatically at more negative , showing a more elastic response. This difference between static and dynamic properties results from the increase in intermolecular and intramolecular interactions between BSA molecules in the PNL at more negative due to the accelerated denaturation of negatively charged BSA that formed complexes with IL cations accumulated on the F side of the F|W interface. The ' and ″ reversibly responded to switching between different potentials (a positive and a negative ). These IRM results unveiled that the viscoelasticity of the PNL at the electrochemical F|W interface is reversibly potential-switchable. The present interface-specific method using the potential control is a new promising method to diversify and switch the PNL structure reversibly. The reversible structural control of the PNL would enable us to perform real-time observation of cells reacting to environmental changes at liquid|liquid interfaces.
通过界面流变测量（IRM）和中子反射测量（NR），在相界电位差（= φ - φ +常数）的外部控制条件下，研究了在水（W）和含氟溶剂（F）之间的电化学液 - 液界面形成的蛋白质纳米层（PNL）。其中，F含有疏水性离子液体（IL）作为支持电解质，pH为7.4的W含有蛋白质牛血清白蛋白（BSA）。IRM和NR结果表明，通过施加 ，电化学F|W界面处PNL的静态和动态特性都会发生变化。NR发现对PNL中BSA的吸附量依赖性最小。相比之下，IRM显示，尽管PNL的界面剪切损耗模量 ″ 与 无关保持恒定，但PNL的界面剪切储能模量 ' 在更负的 时急剧增加，表现出更具弹性的响应。静态和动态特性之间的这种差异是由于在F|W界面F侧积累的IL阳离子与带负电荷的BSA形成复合物，导致带负电荷的BSA加速变性，从而使PNL中BSA分子之间的分子间和分子内相互作用增加。' 和 ″ 对不同电位（正电位和负电位）之间的切换具有可逆响应。这些IRM结果表明，电化学F|W界面处PNL的粘弹性是可逆电位可切换的。目前使用电位控制的界面特异性方法是一种新的有前途的方法，可使PNL结构可逆地多样化和切换。PNL的可逆结构控制将使我们能够实时观察细胞在液 - 液界面处对环境变化的反应。
