(448b) Structure and Dynamics of Water near the Interface with Oligo(Ethylene Oxide) Self-Assembled Monolayers

We performed molecular dynamics simulations of the oligo(ethylene oxide) (OEO) self-assembled monolayers in water to determine the nature of the systems' interfacial structure and dynamics. The density profiles, hydrogen bonding, and water dynamics are calculated as a function of the area per molecule A of the OEO. At the highest coverages, the interface is hydrophobic and a density drop is found at the interface. The interfacial region becomes more like bulk water as A increases. The OEO and water become progressively more mixed and hydrogen bonding increases within the interfacial region. Water mobility is slower within the interfacial region, but not substantially. The implications of our results on the resistance of OEO SAMs to protein adsorption are discussed. Our principal result is that as A increases the increasingly water-like interfacial region provides a more protein-resistant surface. This finding supports recent experimental measurements that protein resistance is maximal for less than full coverage on Au.rage on Au.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract No. DE-AC04-94AL85000.