Simulations of water at the interface with hydrophilic self-assembled monolayers

Simulations of water at hydrophilic self-assembled monolayer (SAM) surfaces are especially relevant for biological interfaces. Well-defined, atomically smooth surfaces that can be continuously varied are possible with SAMs. These characteristics enable more accurate measurements than many other surfaces with the added advantage of tailoring the surface to treat specific chemical groups. A fundamental question is how solid surfaces affect the structure and dynamics of water. Measurements of the structure and dynamics of water at solid surfaces have improved significantly, but there remain differences among the experiments. In this article, the authors review simulations of water at the interface with hydrophilic SAMs. These simulations find that while the interfacial water molecules are slower than the bulk water molecules, the interfacial dynamics remains that of a liquid. A major biological application of SAMs is for making coatings resistant to protein adsorption. SAMs terminated with ethylene glycol monomers have proven to be excellent at resisting protein adsorption. Understanding the mechanisms behind this resistance remains an unresolved issue. Recent simulations suggest a new perspective of the role of interfacial water and the inseparable interplay between the SAM and the water.