The interaction of polypeptides and proteins with an inorganic surface is intrinsically dependent on the interfacial behavior of amino acids and sensitive to solution conditions such as pH, ion type, and salt concentration. A faithful description of amino-acid adsorption remains a theoretical challenge from a molecular perspective due to the strong coupling of local thermodynamic nonideality and inhomogeneous ionization of both the adsorbate and substrate. Building upon a recently developed coarse-grained model for natural amino acids in bulk electrolyte solutions, here we report a molecular theory to predict amino-acid adsorption on ionizable inorganic surfaces over a broad range of solution conditions. In addition to describing the coupled ionization of amino acids and the underlying surface, the thermodynamic model is able to account for both physical binding and surface associations such as hydrogen bonding or bidentate coordination. It is applicable to all types of natural amino acids regardless of the solution pH, salt type and concentration. The theoretical predictions have been validated by extensive comparison with experimental data for the adsorption of acidic, basic, and neutral amino acids at rutile (α-TiO₂) surfaces.

中文翻译：

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无机表面氨基酸吸附的分子热力学

多肽和蛋白质与无机表面的相互作用本质上取决于氨基酸的界面行为，并且对溶液条件（如 pH 值、离子类型和盐浓度）敏感。由于局部热力学非理想性和吸附物和底物的不均匀电离的强耦合，从分子的角度来看，对氨基酸吸附的真实描述仍然是一个理论挑战。基于最近开发的散装电解质溶液中天然氨基酸的粗粒度模型，我们在此报告了一种分子理论来预测氨基酸在广泛的溶液条件下在可电离无机表面上的吸附。除了描述氨基酸和底层表面的耦合电离，热力学模型能够解释物理结合和表面结合，例如氢键或双齿配位。它适用于所有类型的天然氨基酸，无论溶液的 pH 值、盐的类型和浓度如何。通过与金红石（α-TiO₂）表面。