title: Biohybrid glycopolymer capable of ionotropic gelation.
abstract: Ionotropic gelation is particularly appealing for the formation of hydrogels because it takes place under mild conditions, is not thermoreversible, and does not involve toxic chemicals. A well-known example is the gelation of alginate in the presence of calcium ions, which is at the base of numerous applications involving this polymer. In this study, alginate-derived oligosaccharides were converted into acrylamide- and methacrylamide-type macromonomers in two steps without resorting to protective group chemistry. They were then copolymerized with 2-hydroxyethylmethacrylamide in aqueous solution to yield high molar mass biohybrid glycopolymers containing between 25 and 52% by mass of oligosaccharide graft chains. A comparative kinetic study showed that both acrylamide- and methacrylamide-type macromonomers reacted since the early stages of the copolymerization, but that the mole fraction in the polymer was smaller than in the feed up to 50-60% conversion and increased markedly afterward. This effect was slighter for the methacrylamide-type macromonomer though. Copolymers carrying oligosaccharide chains with 16-20 repeating units were synthesized and used for a gelation experiment: When dialyzed against CaCl(2) 0.5 mol L(-1), the polymer carrying (1→4)-α-l-guluronan residues led to a soft isotropic self-standing transparent hydrogel, while the polymer carrying (1→4)-β-d-mannuronan residues gave a loose opaque gel. This study demonstrates that alginate-extracted oligosaccharides and aqueous radical polymerization can be combined for the flexible design of biohybrid glycopolymers capable of ionotropic gelation under very mild conditions.
authors.affiliation: Centre de Recherches sur les Macromolécules Végétales, Grenoble, France.
authors.forename: Ali
authors.initials: A
authors.lastname: Ghadban
authors.forename: Luca
authors.initials: L
authors.lastname: Albertin
authors.forename: Marguerite
authors.initials: M
authors.lastname: Rinaudo
authors.forename: Alain
authors.initials: A
authors.lastname: Heyraud
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000178:Acrylamides; D005782:Gels; D009844:Oligosaccharides; D011108:Polymers; C045985:methacrylamide; D002118:Calcium