title: Influence of pH on the micelle-to-vesicle transition in aqueous mixtures of sodium dodecyl benzenesulfonate with histidine.
abstract: Small unilamellar vesicles (approximately 100 nm in diameter) form spontaneously in aqueous mixtures of histidine and sodium dodecyl benzenesulfonate. By manipulating pH, a gradual transition from micelles to vesicles to bilayers to precipitate is observed. The self-assembly of vesicles occurs over a wide range of compositions when the solution pH is lower than 6.0, the pKa of the imidazole moiety on the histidine molecule. This phenomenon is likely the result of attractive interactions between the negatively charged benzenesulfonate headgroups and the positively charged imidazole group in the amino acid. Similar results are obtained when imidazole salt itself is used.
authors.affiliation: Center for Molecular Engineering and Thermodynamics, University of Delaware, Newark, Delaware 19716, USA.
authors.forename: Yamaira I
authors.initials: YI
authors.lastname: González
authors.forename: Hisanori
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Maria
authors.initials: M
authors.lastname: Stjerndahl
authors.forename: Eric W
authors.initials: EW
authors.lastname: Kaler
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D017666:Deuterium Oxide / Q000737:chemistry; D006639:Histidine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D008823:Micelles; D044367:Phase Transition; D014867:Water / Q000737:chemistry
chemical_list: D001557:Benzenesulfonates; D007093:Imidazoles; D008823:Micelles; D014867:Water; D006639:Histidine; C001114:dodecylbenzenesulfonic acid; C029899:imidazole; D017666:Deuterium Oxide