title: Micelle-like association of polysaccharides with hydrophobic end groups.
abstract: New dextran derivatives with hydrophobic end groups were synthesized by reductive amination of dextran chain ends, followed by chemical modification of the dextran main chain by attachment of cationic groups and/or by crosslinking. Properties of the aggregates formed by hydrophobic association of the end groups were studied by fluorescence, dynamic light scattering, atomic force microscopy and transmission electron microscopy and depended on the length of the dextran chain (6, 10, 25 kDa) and the hydrophobicity of the end group (alkyl, dialkyl, bile acid). All neutral derivatives were able to form micelle-like aggregates above a critical aggregation concentration (0.008-0.159 g/dL). Polarity of the micelle hydrophobic core was close to or lower than that of neutral low molecular surfactants (polarity parameter I1/I3≈0.8-1.13), aggregation number was 20-30 and hydrodynamic radius 20-30 nm. Attachment of cationic groups to the dextran main chain increased critical aggregation concentration and core polarity, but cationic polymeric surfactants with good association ability could be obtained by an appropriate choice of the content and hydrophobicity of the cationic groups. Cross-linking of the micelle shell with divinylsulfone increased micelle stability to dilution.
authors.affiliation: "Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700457 Iasi, Romania. Electronic address: nichifor@icmpp.ro.
authors.forename: Marieta
authors.initials: M
authors.lastname: Nichifor
authors.affiliation: "Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700457 Iasi, Romania.
authors.forename: Georgeta
authors.initials: G
authors.lastname: Mocanu
authors.affiliation: "Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700457 Iasi, Romania.
authors.forename: Magdalena C
authors.initials: MC
authors.lastname: Stanciu
mesh_terms: D002412:Cations / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002412:Cations; D003432:Cross-Linking Reagents; D003911:Dextrans; D008823:Micelles; D013501:Surface-Active Agents
keywords: Dextran; Micelle; Polysaccharide; Semi-telechelic; Surfactant