title: Monolayers (Langmuir films) behavior of multi-component systems composed of a bile acid with different sterols and with their 1:1 mixtures.
abstract: Different physicochemical properties of Langmuir films (monolayers) composed of 10 mixed systems of a bile acid, deoxycholic acid (DC) with various plant sterols, such as stigmasterol (Stig), beta-sitosterol (Sito) and campesterol (Camp) and a stanol, cholestanol (Chsta) in addition to an animal sterol, cholesterol (Ch) [these sterols and Chsta are abbreviated as St] and DC with 1:1 St mixtures; (Ch+Chsta), (Ch+Stig), (Stig+Chsta), (Ch+Sito) and (Ch+Camp) on the substrate of 5M aqueous NaCl solution (pH 1.2) at 25 degrees C, were investigated in terms of mean surface area per molecule (A(m)), the partial molecular area (PMA), surface excess Gibbs energy (DeltaG((ex))), interaction parameter (I(p)) as well as activity coefficients (f(1) and f(2)) in 2-D phase of each binary (or ternary) component system and elasticity (Cs(-1)) of formed films; these were analyzed on the basis of the respective surface pressure (pi) versus A(m) isotherms as a function of mole fraction of Sts (X(st)) in the DC/St(s) mixtures at discrete surface pressures. Notable findings are: (i) all the binary component systems did form patched film type monolayers consisting of (a) DC-dominant film solubilizing a trace amount of St molecules and (b) St dominant film dissolving a small amount of DC molecules, (ii) DC in 2-D phase exhibited a transition from LE film to LC film at a constant pressure (pi(C)(1)) accompanied by compression and (iii) DeltaG((ex)) as well as I(p) was found to be greatly dependent on (a) the combinations of DC with different St species and (b) to be markedly varied by a difference in mixing ratio of DC to Sts. Compressibility (or elasticity) analyses and fluorescence microscopy images could support the above findings as well as interpretation.
authors.affiliation: Department of Chemistry, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan.
authors.forename: Shigemi
authors.initials: S
authors.lastname: Nagadome
authors.forename: Nozomi S
authors.initials: NS
authors.lastname: Suzuki
authors.forename: Yauko
authors.initials: Y
authors.lastname: Mine
authors.forename: Takeo
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Nakahara
authors.forename: Osamu
authors.initials: O
authors.lastname: Shibata
authors.forename: Chien-Hsiang
authors.initials: CH
authors.lastname: Chang
authors.forename: Gohsuke
authors.initials: G
authors.lastname: Sugihara
mesh_terms: D002784:Cholesterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000502:physiology; D003840:Deoxycholic Acid / Q000737:chemistry* / Q000502:physiology; D010840:Phytosterols / Q000737:chemistry*; D012855:Sitosterols / Q000737:chemistry* / Q000378:metabolism; D053835:Unilamellar Liposomes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010840:Phytosterols; D012855:Sitosterols; D053835:Unilamellar Liposomes; D003840:Deoxycholic Acid; C021273:campesterol; C025473:gamma-sitosterol; D002784:Cholesterol