title: Hydrophilic carotenoids: surface properties and aggregation of an astaxanthin-lysine conjugate, a rigid, long-chain, highly unsaturated and highly water-soluble tetracationic bolaamphiphile.
abstract: The surface and aggregation properties of a synthetic, highly water-soluble carotenoid, the tetracationic astaxanthin-lysine conjugate (Asly), have been examined through measurements of surface tension, optical absorption and dynamic light scattering. The following parameters were determined: critical aggregation concentration c(M), surface concentration Gamma, molecular area a(m), free energy of adsorption and aggregation (DeltaG(ad) degrees and DeltaG(M) degrees , respectively), and the aggregate size r(H). The compound forms true monomolecular solutions in water below c(M); aggregates emerge only at rather high concentrations (> or =2.18 mM).
authors.affiliation: Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.
authors.forename: Stine Nalum
authors.initials: SN
authors.lastname: Naess
authors.forename: Hans-Richard
authors.initials: HR
authors.lastname: Sliwka
authors.forename: Vassilia
authors.initials: V
authors.lastname: Partali
authors.forename: Thor Bernt
authors.initials: TB
authors.lastname: Melø
authors.forename: K
authors.initials: K
authors.lastname: Razi Naqvi
authors.forename: Henry L
authors.initials: HL
authors.lastname: Jackson
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Lockwood
mesh_terms: D000042:Absorption; D002338:Carotenoids / Q000737:chemistry*; D008239:Lysine / Q000031:analogs & derivatives* / Q000737:chemistry; D055095:Optics and Photonics; D012542:Scattering, Radiation; D012995:Solubility; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D024341:Xanthophylls / Q000737:chemistry
chemical_list: D013501:Surface-Active Agents; D024341:Xanthophylls; C523360:astaxanthin-lysine conjugate Asly; D014867:Water; D002338:Carotenoids; C005948:astaxanthine; D008239:Lysine