title: Unexpected bilayer formation in Langmuir films of nucleolipids.
abstract: Langmuir monolayers have been extensively investigated by various experimental techniques. These studies allowed an in-depth understanding of the molecular conformation in the layer, phase transitions, and the structure of the multilayer. As the monolayer is compressed and the surface pressure is increased beyond a critical value, usually occurring in the minimal closely packed molecular area, the monolayer fractures and/or folds, forming multilayers in a process referred to as collapse. Various mechanisms for monolayer collapse and the resulting reorganization of the film have been proposed, and only a few studies have demonstrated the formation of a bilayer after collapse and with the use of a Ca(2+) solution. In this work, Langmuir isotherms coupled with imaging ellipsometry and polarization modulation infrared reflection absorption spectroscopy were recorded to investigate the air-water interface properties of Langmuir films of anionic nucleolipids. We report for these new molecules the formation of a quasi-hexagonal packing of bilayer domains at a low compression rate, a singular behavior for lipids at the air-water interface that has not yet been documented.
authors.affiliation: Université Bordeaux, CBMN, UMR 5248, Pessac, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Desbat
authors.forename: Nessim
authors.initials: N
authors.lastname: Arazam
authors.forename: Salim
authors.initials: S
authors.lastname: Khiati
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tonelli
authors.forename: Wilfrid
authors.initials: W
authors.lastname: Neri
authors.forename: Philippe
authors.initials: P
authors.lastname: Barthélémy
authors.forename: Laurence
authors.initials: L
authors.lastname: Navailles
mesh_terms: D002021:Buffers; D002118:Calcium / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D002021:Buffers; D008051:Lipid Bilayers; D002118:Calcium