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Enzyme-Mediated Redox Initiation for Hydrogel Generation and Cellular Encapsulation

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journal contribution
posted on 09.11.2009, 00:00 by Leah M. Johnson, Benjamin D. Fairbanks, Kristi S. Anseth, Christopher N. Bowman
A rapid, water-soluble enzyme-mediated radical chain initiation system involving glucose oxidase and Fe2+ generated hydrogels within minutes at 25 °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 × 10−3 M of glucose. A square root dependence of the initial polymerization rate on Fe2+ concentration was observed between 1.0 × 10−4 M and 5.0 × 10−4 M of Fe2+, whereupon excess Fe2+ reduced final acrylate conversions. The glucose oxidase-mediated initiation system was employed for encapsulation of fibroblasts (NIH3T3s) into a poly(ethylene glycol) tetra-acrylate (Mn ∼ 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.