Physical mechanisms of the interaction between lipid membranes in the aqueous environment

We review various mechanisms underlying the interaction between biological membranes in their aqueous environment. In the first part we describe van der Waals interactions, derive generally-applicable density functional expressions for solute-mediated interactions with a focus on electrostatic interactions across aqueous electrolytes, and discuss interaction mechanisms involving the overlap of structured interfacial water layers. We then turn our attention to the long-debated hydration repulsion and review its quantitative investigation using classical molecular dynamics simulations.