title: Synthesis of amphiphilic 6-carboxypullulan ethers.
abstract: Hydrophobically modified polysaccharides that contain carboxyl groups possess exceptional features for drug delivery and other applications. Carboxyl groups were introduced at C-6 in the pullulan backbone by applying the well-established oxidation with TEMPO and NaOCl/NaBr. The oxidized product, 6-carboxypullulan, is even more water-soluble than pullulan. Consequently, further chemical modifications have been mainly restricted to reactions that can be performed in water or under heterogeneous conditions. We find that the TBA salt of 6-carboxypullulan is soluble in a range of organic solvents and can be reacted homogeneously with various alkyl halides in DMSO and sodium hydroxide at 40 °C to yield 6-carboxypullulan ethers. Complete substitution (DS 7 per trisaccharide repeat unit) was achieved upon reaction with iodoethane, while products from reaction with longer chain alkyl halides (propyl and butyl derivatives) achieved DS up to about 3. The amphiphilic products have impressive surfactant properties.
authors.affiliation: Macromolecules and Interfaces Institute, Virginia Tech, 240 ICTAS, Blacksburg, VA 24061, United States. Electronic address: junia@vt.edu.
authors.forename: Junia M
authors.initials: JM
authors.lastname: Pereira
authors.forename: Michelle
authors.initials: M
authors.lastname: Mahoney
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Edgar
mesh_terms: D060326:Chemistry Techniques, Synthetic; D003497:Cyclic N-Oxides / Q000737:chemistry; D004987:Ethers / Q000737:chemistry*; D005936:Glucans / Q000138:chemical synthesis* / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D010084:Oxidation-Reduction; D012995:Solubility
chemical_list: D003497:Cyclic N-Oxides; D004987:Ethers; D005936:Glucans; C003959:TEMPO
keywords: 6-Carboxypullulan; Amphiphilic; Drug delivery; Etherification; Oxidation; Regioselective synthesis; Surfactant