title: Modular degradable hydrogels based on thiol-reactive oxanorbornadiene linkers.
abstract: Oxanorbornadiene dicarboxylate (OND) reagents are potent Michael acceptors, the adducts of which undergo fragmentation by retro-Diels-Alder reaction at rates that vary with the substitution pattern on the OND moiety. Rapid conjugate addition between thiol-terminated tetravalent PEG and multivalent ONDs yielded self-supporting hydrogels within 1 min at physiological temperature and pH. Erosion of representative hydrogel formulations occurred with predictable and pH-independent rates on the order of minutes to weeks. These materials could be made non-degradable by epoxidation of the OND linkers without slowing gelation. Hydrogels prepared with OND linkers of equal valence had comparable physical properties, as determined by equilibrium swelling behavior, indicating similar internal network structure. Diffusion and release of entrained cargo varied with both the rate of degradation of PEG-OND hydrogels and the hydrodynamic radius of the entrained species. These results highlight the utility of OND linkers in the preparation of degradable network materials with potential applications in sustained release.
authors: †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.
authors: Cody J
authors: CJ
authors: Higginson
authors: Seung Yeon
authors: SY
authors: Kim
authors: Miguel
authors: M
authors: Peláez-Fernández
authors: Alberto
authors: A
authors: Fernández-Nieves
authors: †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.
authors: M G
authors: MG
authors: Finn
mesh_terms: D004852:Epoxy Compounds / Q000737:chemistry*; D057446:Hydrodynamics; D020100:Hydrogels / Q000737:chemistry*; D015394:Molecular Structure; D009636:Norbornanes / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004852:Epoxy Compounds; D020100:Hydrogels; D009636:Norbornanes; D013438:Sulfhydryl Compounds