title: Light-responsive iron(III)-polysaccharide coordination hydrogels for controlled delivery.
abstract: Visible-light responsive gels were prepared from two plant-origin polyuronic acids (PUAs), alginate and pectate, coordinated to Fe(III) ions. Comparative quantitative studies of the photochemistry of these systems revealed unexpected differences in the photoreactivity of the materials, depending on the polysaccharide and its composition. The roles that different functional groups play on the photochemistry of these biomolecules were also examined. Mannuronic-rich alginates were more photoreactive than guluronic acid-rich alginate and than pectate. The microstructure of alginates with different mannuronate-to-guluronate ratios changed with polysaccharide composition. This influenced the gel morphology and the photoreactivity. Coordination hydrogel beads were prepared from both Fe-alginate and Fe-pectate. The beads were stable carriers of molecules as diverse as the dye Congo Red, the vitamin folic acid, and the antibiotic chloramphenicol. The photoreactivity of the hydrogel beads mirrored the photoreactivity of the polysaccharides in solution, where beads prepared with alginate released their cargo faster than beads prepared with pectate. These results indicate important structure-function relationships in these systems and create guidelines for the design of biocompatible polysaccharide-based materials where photoreactivity and controlled release can be tuned on the basis of the type of polysaccharide used and the metal coordination environment.
authors.affiliation: Center for Photochemical Sciences and Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States.
authors.forename: Giuseppe E
authors.initials: GE
authors.lastname: Giammanco
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Sosnofsky
authors.forename: Alexis D
authors.initials: AD
authors.lastname: Ostrowski
mesh_terms: D000464:Alginates / Q000737:chemistry* / Q000528:radiation effects; D003692:Delayed-Action Preparations / Q000737:chemistry* / Q000528:radiation effects; D020723:Glucuronic Acid / Q000737:chemistry / Q000528:radiation effects; D006603:Hexuronic Acids / Q000737:chemistry / Q000528:radiation effects; D020100:Hydrogels / Q000737:chemistry* / Q000528:radiation effects; D007501:Iron / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008422:Materials Testing; D010368:Pectins / Q000737:chemistry* / Q000528:radiation effects; D011134:Polysaccharides / Q000737:chemistry / Q000528:radiation effects
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D006603:Hexuronic Acids; D020100:Hydrogels; D011134:Polysaccharides; D010368:Pectins; D020723:Glucuronic Acid; D007501:Iron; C003181:polygalacturonic acid
keywords: controlled release; coordination hydrogels; photochemistry; polysaccharides; stimuli-responsive materials