Using the long-range nature of electrostatic forces to create defined lateral molecular distributions in langmuir-blodgett films

Fluorescence microscopic observations with lipid monolayers in the fluid/ordered phase coexistence range are reviewed to conclude on the interplay of nucleation kinetics, line tension and long-range electrostatic forces. The latter arise from the orientation of molecular dipoles at the interface and cause periodic lamellar or hexagonal superstructures. They enable manipulation of lipid domains in electric fields and may be responsible for instabilities of phase boundaries. Due to these forces also J-aggregates formed by adsorption from the subphase are shown to form periodic superstructures. For a ternary system existing of the protein concanavalin A and two lipid phases a phase separation is demonstrated with the lateral distribution of the phases determined by electrostatic forces. The ordered lipid phases are shown to exhibit long-range orientational and short-range positional order.