Nanotubes and bilayers in a model peptide system

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title = "Nanotubes and bilayers in a model peptide system",
abstract = "The trifluoroacetate (tfa) salt of the peptide (ala)(6)lys self-assembles in water into very long, hollow nanotubes with a radius R = 26 nm, above a critical aggregation concentration (volume fraction), phi(cac) = 0.10. The peptides carry a net positive charge that ensures colloidal stability of the self-assembly structures through a long-range electrostatic repulsion. There is only a weak temperature dependence of phi(cac) from which an enthalpy of aggregation of -k(B)T per molecule is estimated. SAXS data show that the thickness of the nanotube wall, delta, is less than 1 nm indicating that the peptides form a monolayer in the nanotube wall. The nanotubes have a very large aspect ratio and form an ordered nematic or hexagonal phase. Because of the low delta/R ratio, the nanotube volume fraction grows very rapidly with increasing peptide concentration, phi, and reaches close packing already at phi = 0.15. When increasing the concentration further, there is a phase transition to a novel lamellar phase where the peptide molecules form bilayers consisting of two, presumably oppositely oriented, monolayers.",
author = "Celen Cenker and Seyda Bucak and Ulf Olsson",
year = "2011",
doi = "10.1039/c0sm01186j",
language = "English",
volume = "7",
pages = "4868--4875",
journal = "Soft Matter",
issn = "1744-6848",
publisher = "Royal Society of Chemistry",
number = "10",