Behavior of water in contact with model hydrophobic cavities and tunnels and carbon nanotubes

Schulz, Erica P.; Alarcón, L. M.; Appignanesi, Gustavo A.

doi:10.1140/epje/i2011-11114-8

Cited by 23 publications

(21 citation statements)

References 20 publications

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“…While it is generally believed that small protein cavities are empty [9], there is no general consensus on whether large protein cavities are filled or empty and certain experimental results on the subject are contradictory (even when certain large cavities seem to indeed present small clusters of confined water molecules) [9,8]. In turn, it has been shown that subnanometric nonpolar cavities (spherical pores) remain empty, whereas water penetrates nanometric size ones [8,14,15]. This behavior is due to the reluctance of the water molecules to resign hydrogen bond coordination with other water molecules (only nanometric size cavities allow penetration retaining the coordination typical at surfaces).…”

Section: Introductionmentioning

confidence: 99%

Hydrophobicity and geometry: Water at curved graphitic-like surfaces and within model pores in self-assembled monolayers

Alarcón

Accordino

et al. 2014

Fluid Phase Equilibria

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Section: Introductionmentioning

confidence: 99%

Hydrophobicity and geometry: Water at curved graphitic-like surfaces and within model pores in self-assembled monolayers

Alarcón

Accordino

et al. 2014

Fluid Phase Equilibria

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“…Thus, since in complex realistic systems both geometry and chemistry affect its hydration properties, it becomes convenient to first separate them by focusing in simple systems to study the role of geometry to then consider more realistic contexts like, for example, proteins and phospholipid membranes. In this section we review our computational work on model hydrophobic surfaces: a graphene sheet, single-walled carbon nanotubes of different radii and C 60 and C 20 fullerenes (Malaspina et al 2010;Alarcón et al 2011;Accordino et al 2011aAccordino et al , 2012aGelman Constantin et al 2011;Schulz et al 2011). Given the chemical similarity between the three kinds of systems under study, the hydration of the graphene sheet should constitute the limit of infinite curvature radius for both the nanotubes and the fullerenes.…”

Section: Hydration and Geometrymentioning

confidence: 99%

“…However, the picture of (nano) confined water is still far from being complete (Giovambattista et al 2012;Rasaiah et al 2008;Berne et al 2009;Schulz et al 2011;Alarcón et al 2014). This issue is not only crucial from an intrinsic, fundamental level, but also from its far reaching implications (Fernández 2010;Qvist et al 2008;Berne et al 2009;Young et al 2007;Wang et al 2011;Kulp III et al 2011;Accordino et al 2011aAccordino et al , 2012aAccordino et al , b, c, 2013Schulz et al 2011;Sierra et al 2013;Alarcón et al 2014;Bogan and Thorn 1998;Li and Liu 2009). For example, being water the matrix of life, a full understanding of its behavior in the nano and mesoscales would be essential to understand biology at the molecular level.…”

Section: Introductionmentioning

confidence: 99%

Hydration and Nanoconfined Water: Insights from Computer Simulations

Alarcón

Fris

Morini

et al. 2015

Subcellular Biochemistry

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The comprehension of the structure and behavior of water at interfaces and under nanoconfinement represents an issue of major concern in several central research areas like hydration, reaction dynamics and biology. From one side, water is known to play a dominant role in the structuring, the dynamics and the functionality of biological molecules, governing main processes like protein folding, protein binding and biological function. In turn, the same principles that rule biological organization at the molecular level are also operative for materials science processes that take place within a water environment, being responsible for the self-assembly of molecular structures to create synthetic supramolecular nanometrically-sized materials. Thus, the understanding of the principles of water hydration, including the development of a theory of hydrophobicity at the nanoscale, is imperative both from a fundamental and an applied standpoint. In this work we present some molecular dynamics studies of the structure and dynamics of water at different interfaces or confinement conditions, ranging from simple model hydrophobic interfaces with different geometrical constraints (in order to single out curvature effects), to self-assembled monolayers, proteins and phospholipid membranes. The tendency of the water molecules to sacrifice the lowest hydrogen bond (HB) coordination as possible at extended interfaces is revealed. This fact makes the first hydration layers to be highly oriented, in some situations even resembling the structure of hexagonal ice. A similar trend to maximize the number of HBs is shown to hold in cavity filling, with small subnanometric hydrophobic cavities remaining empty while larger cavities display an alternation of filled and dry states with a significant inner HB network. We also study interfaces with complex chemical and geometrical nature in order to determine how different conditions affect the local hydration properties. Thus, we show some results for protein hydration and, particularly, some preliminary studies on membrane hydration. Finally, calculations of a local hydrophobicity measure of relevance for binding and self-assembly are also presented. We then conclude with a few words of further emphasis on the relevance of this kind of knowledge to biology and to the design of new materials by highlighting the context-dependent and non-additive nature of different non-covalent interactions in an aqueous nanoenvironment, an issue that is usually greatly overlooked.

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“…Even when recognized as central to main research fields like protein stability, protein folding, protein binding, and biological function, the understanding of the structure and behavior of hydration water is still far from being complete [1][2][3][4][5][6][7][8][9][10]. To this end, molecular dynamics simulations have played an important role and both the hydration of simple model surfaces (where geometry would be the main determinant) and of proteins have been studied [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…To this end, molecular dynamics simulations have played an important role and both the hydration of simple model surfaces (where geometry would be the main determinant) and of proteins have been studied [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Such studies are bringing in a picture in which the first layers of hydration water tend to be more structured than the bulk and (depending on the kind of surface) possibly assuming preferential orientations with respect to the surface normal.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the structure of protein hydration water and the liquid-liquid transition

et al. 2012

Self Cite

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We study the temperature dependence of the structure and orientation of the first hydration layers of the protein lysozyme and compare it with the situation for a model homogeneous hydrophobic surface, a graphene sheet. We show that in both cases these layers are significantly better structured than bulk water. The geometrical constraint of the interface makes the water molecules adjacent to the surface lose one water-water hydrogen bond and expel the fourth neighbors away from the surface, lowering local density. We show that a decrease in temperature improves the ordering of the hydration water molecules, preserving such a geometrical effect. For the case of graphene, this favors an ice Ih-like local structuring, similar to the water-air interface but in the opposite way along the c axis of the basal plane (while the vicinal water molecules of the air interface orient a hydrogen atom toward the surface, the oxygens of the water molecules close to the graphene plane orient a lone pair in such a direction). In turn, the case of the first hydration layers of the lysozyme molecule is shown to be more complicated, but still displaying signs of both kinds of behavior, together with a tendency of the proximal water molecules to hydrogen bond to the protein both as donors and as acceptors. Additionally, we make evident the existence of signatures of a liquid-liquid transition (Widom line crossing) in different structural parameters at the temperature corresponding to the dynamic transition incorrectly referred to as "the protein glass transition."

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Behavior of water in contact with model hydrophobic cavities and tunnels and carbon nanotubes

Cited by 23 publications

References 20 publications

Hydrophobicity and geometry: Water at curved graphitic-like surfaces and within model pores in self-assembled monolayers

Hydrophobicity and geometry: Water at curved graphitic-like surfaces and within model pores in self-assembled monolayers

Hydration and Nanoconfined Water: Insights from Computer Simulations

Temperature dependence of the structure of protein hydration water and the liquid-liquid transition

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