title: Enzyme-mediated redox initiation for hydrogel generation and cellular encapsulation.
abstract: A rapid, water-soluble enzyme-mediated radical chain initiation system involving glucose oxidase and Fe(2+) generated hydrogels within minutes at 25 degrees C and in ambient oxygen. The initiation components were evaluated for their effect on polymerization rates of hydroxyethyl acrylate-poly(ethylene glycol)(575) diacrylate comonomer solutions using near-infrared spectroscopy. Increasing glucose concentration increased polymerization rates until reaching a rate plateau above 1 x 10(-3) M of glucose. A square root dependence of the initial polymerization rate on Fe(2+) concentration was observed between 1.0 x 10(-4) M and 5.0 x 10(-4) M of Fe(2+), whereupon excess Fe(2+) reduced final acrylate conversions. The glucose oxidase-mediated initiation system was employed for encapsulation of fibroblasts (NIH3T3s) into a poly(ethylene glycol) tetra-acrylate (M(n) approximately 20000) hydrogel scaffold demonstrating 96% (+/-3%) viability at 24 h postencapsulation. This first use of enzyme-mediated redox radical chain initiation for cellular encapsulation demonstrates polymerization of hydrogels in situ with kinetic control, minimal oxygen inhibition issues, and utilization of low initiator concentrations.
authors.affiliation: Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Leah M
authors.initials: LM
authors.lastname: Johnson
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Fairbanks
authors.forename: Kristi S
authors.initials: KS
authors.lastname: Anseth
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Bowman
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D057075:Enzyme Assays / Q000379:methods*; D005949:Glucose Oxidase / Q000502:physiology; D020100:Hydrogels / Q000138:chemical synthesis* / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction
chemical_list: D020100:Hydrogels; D005949:Glucose Oxidase