Effects of free radical initiators on polyethylene glycol dimethacrylate hydrogel properties and biocompatibility

• Published in: Journal of biomedical materials research. Part A 2017-11, Vol.105 (11), p.3059-3068
• Main Authors: Wilems, Thomas S., Lu, Xi, Kurosu, Yuki E., Khan, Zara, Lim, Hyun Ju, Smith Callahan, Laura A.
• Format: Article
• Language: English
• Subjects: Ammonium; Ammonium peroxodisulfate; Ammonium Sulfate - chemistry; Ammonium Sulfate - toxicity; Animals; Biocompatibility; Biocompatible Materials - chemistry; Biocompatible Materials - toxicity; Cell Line; Cell Survival - drug effects; Cells, Immobilized - cytology; Cells, Immobilized - drug effects; Chain transfer; cytocompatibility; Dithiothreitol; Elastic Modulus; Embryo cells; fenton chemistry; free radical initiator; Free radicals; Free Radicals - chemistry; Free Radicals - toxicity; Gelation; human induced pluripotent stem cell; Humans; hydrogel; Hydrogel, Polyethylene Glycol Dimethacrylate - chemistry; Hydrogel, Polyethylene Glycol Dimethacrylate - toxicity; Hydrogels; Induced Pluripotent Stem Cells - cytology; Induced Pluripotent Stem Cells - drug effects; Initiators; Mechanical properties; Mice; Modulus of elasticity; Mouse Embryonic Stem Cells - cytology; Mouse Embryonic Stem Cells - drug effects; Neural stem cells; Neural Stem Cells - cytology; Neural Stem Cells - drug effects; Oxidation; Pluripotency; Polyethylene glycol; Polyethylenes; Polymerization; Propane - analogs & derivatives; Propane - chemistry; Propane - toxicity; Redox reactions; Shear modulus; Spinal cord; Stem cell transplantation; Stem cells; Thiols; Tissue engineering; Ultraviolet radiation
• ISSN: 1549-3296; 1552-4965
• DOI: 10.1002/jbm.a.36160

Many studies have utilized Irgacure 2959 photopolymerized poly(ethylene glycol) (PEG) hydrogels for tissue engineering application development. Due to the limited penetration of ultraviolet light through tissue, Irgacure 2959 polymerized hydrogels are not suitable for use in tissues where material injection is desirable, such as the spinal cord. To address this, several free radical initiators (thermal initiator VA044, ammonium persulfate (APS)/TEMED reduction–oxidation reaction, and Fenton chemistry) are evaluated for their effects on the material and mechanical properties of PEG hydrogels compared with Irgacure 2959. To emulate the effects of endogenous thiols on in vivo polymerization, the effects of chain transfer agent (CTA) dithiothreitol on gelation rates, material properties, Young's and shear modulus, are examined. Mouse embryonic stem cells and human induced pluripotent stem cell derived neural stem cells were used to investigate the cytocompatibility of each polymerization. VA044 and Fenton chemistry polymerization of PEG hydrogels both had gelation rates and mechanical properties that were highly susceptible to changes in CTA concentration and showed poor cytocompatibility. APS/TEMED polymerized hydrogels maintained consistent gelation rates and mechanical properties at high CTA concentration and had a similar cytocompatibility as Irgacure 2959 when cells were encapsulated within the PEG hydrogels. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3059–3068, 2017.