Xue Jinling, Ji Mingyu, Lu Yuanyuan, Pan Dan, Yang Xiao, Yang Xiaoning, Xu Zhijun
College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
Zhangjiagang Institute of Nanjing Tech University, Zhangjiagang 215699, China.
Phys Chem Chem Phys. 2024 Mar 13;26(11):8704-8715. doi: 10.1039/d3cp05669d.
Despite extensive studies on the thermodynamic mechanism governing molecular adsorption at the solid-water interface, a comprehensive understanding of the crucial role of interface properties in mediating the entropy-enthalpy compensation during adsorption is lacking, particularly at a quantitative level. Herein, we employed two types of surface models (hydroxyapatite and graphene) along with a series of amino acids to successfully elucidate how distinct interfacial features dictate the delicate balance between entropy and enthalpy variations. The adsorption of all amino acids on the hydroxyapatite surface is an enthalpy-dominated process, where the water-induced enthalpic component of the free energy and the surface-adsorbate electrostatic interaction term alternatively act as the driving force for adsorption in different regions of the surface. Although favorable interactions are observed between amino acids and the graphene surface, the entropy-enthalpy compensation exhibits dependence on the molecular size of the adsorbates. For small amino acids, favorable enthalpy changes predominantly determine their adsorption behavior; however, larger amino acids tend to bind more tightly with the graphene surface, which is thermodynamically dominated by the entropy variations despite the structural characteristics of amino acids. This study reveals specific entropy-enthalpy mechanisms underlying amino acid adsorption at the solid-liquid interface, providing guidance for surface design and synthesis of new biomolecules.
尽管对控制分子在固 - 水界面吸附的热力学机制进行了广泛研究，但仍缺乏对界面性质在吸附过程中介导熵 - 焓补偿的关键作用的全面理解，尤其是在定量层面。在此，我们采用了两种类型的表面模型（羟基磷灰石和石墨烯）以及一系列氨基酸，成功阐明了不同的界面特征如何决定熵变和焓变之间的微妙平衡。所有氨基酸在羟基磷灰石表面的吸附是一个以焓为主导的过程，其中水诱导的自由能焓分量和表面 - 吸附质静电相互作用项在表面的不同区域交替充当吸附的驱动力。尽管观察到氨基酸与石墨烯表面之间存在有利的相互作用，但熵 - 焓补偿表现出对吸附质分子大小的依赖性。对于小氨基酸，有利的焓变主要决定其吸附行为；然而，较大的氨基酸倾向于与石墨烯表面更紧密地结合，尽管氨基酸具有结构特征，但在热力学上这主要由熵变主导。这项研究揭示了氨基酸在固 - 液界面吸附背后的特定熵 - 焓机制，为新型生物分子的表面设计和合成提供了指导。
