AVS 49th International Symposium
    Biomaterials Tuesday Sessions
       Session BI-TuP

Paper BI-TuP1
Computer Simulation of Water Near Structureless Model Surfaces and Self-assembled Monolayers: Interfacial Behavior and Hydration Forces

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Biointerfaces and Surfaces I
Presenter: T. Hayashi, Heidelberg Universität, Germany
Authors: T. Hayashi, Heidelberg Universität, Germany
A.J. Pertsin, Heidelberg Universität, Germany
M. Grunze, Heidelberg Universität, Germany
Correspondent: Click to Email
The hydration forces between both structureless and structured surfaces are calculated using the grand canonical Monte Carlo technique. Primary attention is given to large surface-to-surface separations (40 Å and more), where the oscillations of the hydration force have practically decayed. For simulations of structureless surfaces, both orientation independent and strongly directional potentials are employed. Our results show that water confined between hydrophobic surfaces experiences a capillary evaporation at surface-to-surface separations less than about 58 Å. At larger separations, hydrophobic attraction due to a density depression in the confined region is observed. In cases of hydrophilic surfaces, the sign and magnitude of hydration force are found to be strongly dependent on the presence of orientation dependent terms in the water-surface potential. Simulations of structured surfaces were performed with methoxy tri(ethylene glycol) terminated alkane thiol self-assembled monolayers (SAMs) on the Au(111) and Ag(111) substrates. Although both of the SAMs show a typical hydrophobic behavior similar to that observed with structureless hydrophobic surfaces, there are substantial differences in their interaction with water. The simulation results are discussed in the context of the experimentally observed protein adsorption properties and surface force behavior between the SAMs.