title: Effects of Bile Salt Sodium Glycodeoxycholate on the Self-Assembly of PEO-PPO-PEO Triblock Copolymer P123 in Aqueous Solution.
abstract: A comprehensive experimental study on the interaction between the PEO-PPO-PEO block copolymer P123 (EO20PO68EO20) and the anionic bile salt sodium glycodeoxycholate (NaGDC) in water has been performed. The work was aimed at investigating the suitability of using P123 as bile salt sequestrant beside the fundamental aspects of PEO-PPO-PEO block copolymer-bile salt interactions. Various experimental techniques including dynamic and static light scattering, small-angle X-ray scattering, and differential scanning calorimetry (DSC) were employed in combination with electrophoretic mobility measurements. The system was investigated at a constant P123 concentration of 1.74 mM and with varying bile salt concentrations up to approximately 250 mM NaGDC (or a molar ratio n(NaGDC)/n(P123) = 144). In the mixed P123-NaGDC solutions, the endothermic process related to the self-assembly of P123 was observed to gradually decrease in enthalpy and shift to higher temperatures upon progressive addition of NaGDC. To explain this effect, the formation of NaGDC micelles carrying partly dehydrated P123 unimers was proposed and translated into a stoichiometric model, which was able to fit the experimental DSC data. In the mixtures at low molar ratios, NaGDC monomers associated with the P123 micelle forming a charged "P123 micelle-NaGDC" complex with a dehydrated PPO core. These complexes disintegrated upon increasing NaGDC concentration to form small "NaGDC-P123" complexes visualized as bile salt micelles including one or a few P123 copolymer chains.
authors.affiliation: Division of Physical Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Solmaz
authors.initials: S
authors.lastname: Bayati
authors.affiliation: Department of Chemistry, Sapienza University of Rome , P. le A. Moro 5, 00185 Rome, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Galantini
authors.affiliation: Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller, Norway.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Knudsen
authors.affiliation: Division of Physical Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Schillén
mesh_terms: D001647:Bile Acids and Salts / Q000737:chemistry*; D006002:Glycodeoxycholic Acid / Q000737:chemistry*; D015394:Molecular Structure; D011060:Poloxalene / Q000138:chemical synthesis* / Q000737:chemistry*; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D001647:Bile Acids and Salts; D012996:Solutions; D014867:Water; C464484:pluronic block copolymer P123; D006002:Glycodeoxycholic Acid; D011060:Poloxalene