title: Towards a fully-synthetic substitute of alginate: development of a new process using thermal gelation and chemical cross-linking.
abstract: We have previously described a gelation process based on the occurrence of both physical and a chemical mechanisms ('tandem process'), in which a telechelic linear poly(propylene glycol)-bl-poly(ethylene glycol)-bl-poly(propylene glycol) is first thermally gelled and subsequently covalently cross-linked by the reaction of polymer end groups at the termini of the copolymer. The quick kinetics of the reverse thermal gelation and the harmless character of the Michael-type addition between two sets of terminal groups, acrylates on one set and thiols on the other, allows irreversibly cross-linked hydrogels to be obtained in a rapid and biocompatible fashion, even when gelation was conducted in direct contact with cells. This allows in principle for an application of the tandem process in cell encapsulation. In the present work, we have optimized the macromolecular architecture and functionality of the precursors for allowing the use of the tandem process in encapsulation devices designed for calcium alginate. The mechanical, diffusional and biocompatibility properties of these materials were characterized; the comparison of mass transport properties of the tandem gels with those of calcium alginate suggests a similar or even better immunoisolation effect.
authors.affiliation: Department of Materials, Swiss Federal Institute of Technology, 8044 Zurich, Switzerland.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cellesi
authors.forename: Nicola
authors.initials: N
authors.lastname: Tirelli
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hubbell
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D018929:Cell Culture Techniques / Q000379:methods*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000737:chemistry; D005347:Fibroblasts / Q000166:cytology*; D020723:Glucuronic Acid / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011409:Propylene Glycols / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013696:Temperature
chemical_list: D000179:Acrylates; D000464:Alginates; D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D006603:Hexuronic Acids; D020100:Hydrogels; D011108:Polymers; D011409:Propylene Glycols; D013438:Sulfhydryl Compounds; C012504:polypropylene glycol; D011092:Polyethylene Glycols; D020723:Glucuronic Acid; C005732:thioacetic acid