Characterizing Hydration Properties Based on the Orientational Structure of Interfacial Water Molecules

Shin, Sungwon; Willard, Adam P.

doi:10.1021/acs.jctc.7b00898

Cited by 39 publications

(60 citation statements)

References 30 publications

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“…S13). Although not pursued here, we expect that other estimates of local surface hydrophilicity (34,35) will provide qualitatively similar results.…”

Section: Orientation-specific Surface−water Interactions Drive Mobilimentioning

confidence: 81%

Computational discovery of chemically patterned surfaces that effect unique hydration water dynamics

Monroe

Shell

2018

Proc. Natl. Acad. Sci. U.S.A.

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The interactions of water with solid surfaces govern their apparent hydrophobicity/hydrophilicity, influenced at the molecular scale by surface coverage of chemical groups of varied nonpolar/polar character. Recently, it has become clear that the precise patterning of surface groups, and not simply average surface coverage, has a significant impact on the structure and thermodynamics of hydration layer water, and, in turn, on macroscopic interfacial properties. Here we show that patterning also controls the dynamics of hydration water, a behavior frequently thought to be leveraged by biomolecules to influence functional dynamics, but yet to be generalized. To uncover the role of surface heterogeneities, we couple a genetic algorithm to iterative molecular dynamics simulations to design the patterning of surface functional groups, at fixed coverage, to either minimize or maximize proximal water diffusivity. Optimized surface configurations reveal that clustering of hydrophilic groups increases hydration water mobility, while dispersing them decreases it, but only if hydrophilic moieties interact with water through directional, hydrogen-bonding interactions. Remarkably, we find that, across different surfaces, coverages, and patterns, both the chemical potential for inserting a methane-sized hydrophobe near the interface and, in particular, the hydration water orientational entropy serve as strong predictors for hydration water diffusivity, suggesting that these simple thermodynamic quantities encode the way surfaces control water dynamics. These results suggest a deep and intriguing connection between hydration water thermodynamics and dynamics, demonstrating that subnanometer chemical surface patterning is an important design parameter for engineering solid-water interfaces with applications spanning separations to catalysis.

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“…S13). Although not pursued here, we expect that other estimates of local surface hydrophilicity (34,35) will provide qualitatively similar results.…”

Section: Orientation-specific Surface−water Interactions Drive Mobilimentioning

confidence: 81%

Computational discovery of chemically patterned surfaces that effect unique hydration water dynamics

Monroe

Shell

2018

Proc. Natl. Acad. Sci. U.S.A.

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“…As described in Ref. 36, this order parameter is capable of distinguishing hydrophobic and hydrophilic surfaces based only on the effect of these surfaces on aqueous interfacial molecular structure. Furthermore, δλ phob can be formulated as a local order parameter to generate spatially resolved maps of water's interfacial molecular structure.…”

Section: A Disordered Model Surface With Tunable Hydrophilicitymentioning

confidence: 99%

Water’s Interfacial Hydrogen Bonding Structure Reveals the Effective Strength of Surface–Water Interactions

Shin

Willard

2018

J. Phys. Chem. B

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The interactions of a hydrophilic surface with water can significantly influence the characteristics of the liquid water interface. In this manuscript, we explore this influence by studying the molecular structure of liquid water at a disordered surface with tunable surface-water interactions. We combine all-atom molecular dynamics simulations with a mean field model of interfacial hydrogen bonding to analyze the effect of surface-water interactions on the structural and energetic properties of the liquid water interface. We find that the molecular structure of water at a weakly interacting (i.e., hydrophobic) surface is resistant to change unless the strength of surface-water interactions is above a certain threshold. We find that below this threshold water's interfacial structure is homogeneous and insensitive to the details of the disordered surface, however, above this threshold water's interfacial structure is heterogeneous. Despite this heterogeneity, we demonstrate that the equilibrium distribution of molecular orientations can be used to quantify the energetic component of the surface-water interactions that contribute specifically to modifying the interfacial hydrogen bonding network. We identify this specific energetic component as a new measure of hydrophilicity, which we refer to as the intrinsic hydropathy.

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“…Such definitions overlook the physical nature of interactions between macromolecule and water and the ability of water molecules to mediate binding based on its location around the macromolecule (e.g., Ikura et al, 2004 ). This also overlooks the fact that the hydrophobic surface patches or cavities are naturally not very hydrated, while the hydrophilic patches are (Barnes et al, 2017 ; Yang et al, 2017 ; Shin and Willard, 2018 ). Therefore, a physically sound protocol that delivers a MS should not only account for the geometry but also consider the physio-chemical properties of a macromolecular surface.…”

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confidence: 99%

Gaussian-Based Smooth Dielectric Function: A Surface-Free Approach for Modeling Macromolecular Binding in Solvents

Chakravorty

Jia

Peng

et al. 2018

Front. Mol. Biosci.

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Conventional modeling techniques to model macromolecular solvation and its effect on binding in the framework of Poisson-Boltzmann based implicit solvent models make use of a geometrically defined surface to depict the separation of macromolecular interior (low dielectric constant) from the solvent phase (high dielectric constant). Though this simplification saves time and computational resources without significantly compromising the accuracy of free energy calculations, it bypasses some of the key physio-chemical properties of the solute-solvent interface, e.g., the altered flexibility of water molecules and that of side chains at the interface, which results in dielectric properties different from both bulk water and macromolecular interior, respectively. Here we present a Gaussian-based smooth dielectric model, an inhomogeneous dielectric distribution model that mimics the effect of macromolecular flexibility and captures the altered properties of surface bound water molecules. Thus, the model delivers a smooth transition of dielectric properties from the macromolecular interior to the solvent phase, eliminating any unphysical surface separating the two phases. Using various examples of macromolecular binding, we demonstrate its utility and illustrate the comparison with the conventional 2-dielectric model. We also showcase some additional abilities of this model, viz. to account for the effect of electrolytes in the solution and to render the distribution profile of water across a lipid membrane.

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Characterizing Hydration Properties Based on the Orientational Structure of Interfacial Water Molecules

Cited by 39 publications

References 30 publications

Computational discovery of chemically patterned surfaces that effect unique hydration water dynamics

Computational discovery of chemically patterned surfaces that effect unique hydration water dynamics

Water’s Interfacial Hydrogen Bonding Structure Reveals the Effective Strength of Surface–Water Interactions

Gaussian-Based Smooth Dielectric Function: A Surface-Free Approach for Modeling Macromolecular Binding in Solvents

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