title: Interaction of the biosurfactant, Surfactin with betaines in aqueous solution.
abstract: The interactions between the lipopeptide Surfactin and four betaines, N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SDDAB), N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (STDAB), N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SHDAB), and N-dodecyl-N,N-dimethyl-2-ammonio-acetate (C12BE) are studied by surface tension and small-angle neutron scattering (SANS). SDDAB, STDAB, and SHDAB have the same headgroup but different hydrophobic chains. C12BE has different headgroup but the same hydrophobic chain with SDDAB. According to the interfacial parameters calculated from surface tension, the synergism between Surfactin and betaine is relevant with the molecule structure of betaine and the mole ratio of them. For betaines, the optimum alkyl chain length (STDAB) and long enough separation between positive charge and negative charge in headgroup are responsible for highest synergetic interaction with Surfactin. The aggregates of individual Surfactin and the mixtures of Surfactin and sulfopropyl betaines are predicted to be spherical based on the packing parameter (pp) and the average packing parameter (P(av)), which is in close qualitative agreement with SANS data analysis, while Surfactin/C12BE forms ellipsoidal micelles due to the smaller headgroup of C12BE.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Jingwen
authors.initials: J
authors.lastname: Xiao
authors.forename: Vasil M
authors.initials: VM
authors.lastname: Garamus
authors.forename: László
authors.initials: L
authors.lastname: Almásy
authors.forename: Regine
authors.initials: R
authors.lastname: Willumeit
authors.forename: Bozhong
authors.initials: B
authors.lastname: Mu
authors.forename: Aihua
authors.initials: A
authors.lastname: Zou
mesh_terms: D001622:Betaine / Q000737:chemistry*; D004347:Drug Interactions; D055666:Lipopeptides / Q000737:chemistry*; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D055666:Lipopeptides; D010456:Peptides, Cyclic; D013501:Surface-Active Agents; C009365:surfactin peptide; D001622:Betaine