American Chemical Society
bm900712j_si_001.pdf (178.71 kB)

Photo-Cross-Linked Hydrogels from Thermoresponsive PEGMEMA-PPGMA-EGDMA Copolymers Containing Multiple Methacrylate Groups: Mechanical Property, Swelling, Protein Release, and Cytotoxicity

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journal contribution
posted on 2009-10-12, 00:00 authored by Hongyun Tai, Daniel Howard, Seiji Takae, Wenxin Wang, Tina Vermonden, Wim E. Hennink, Patrick S. Stayton, Allan S. Hoffman, Andreas Endruweit, Cameron Alexander, Steven M. Howdle, Kevin M. Shakesheff
Photo-cross-linked hydrogels from thermoresponsive polymers can be used as advanced injectable biomaterials via a combination of physical interaction (in situ thermal gelation) and covalent cross-links (in situ photopolymerization). This can lead to gels with significantly enhanced mechanical properties compared to non-photo-cross-linked thermoresponsive hydrogels. Moreover, the thermally phase-separated gels have attractive advantages over non-thermoresponsive gels because thermal gelation upon injection allows easy handling and holds the shape of the gels prior to photopolymerization. In this study, water-soluble thermoresponsive copolymers containing multiple methacrylate groups were synthesized via one-step deactivation enhanced atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, Mn = 475), poly(propylene glycol) methacrylate (PPGMA, Mn = 375), and ethylene glycol dimethacrylate (EGDMA) and were used to form covalent cross-linked hydrogels by photopolymerization. The cross-linking density was found to have a significant influence on the mechanical and swelling properties of the photo-cross-linked gels. Release studies using lysozyme as a model protein demonstrated a sustained release profile that varied dependent on the copolymer composition, cross-linking density, and the temperature. Mouse C2C12 myoblast cells were cultured in the presence of the copolymers at concentrations up to 1 mg/mL. It was found that the majority of the cells remained viable, as assessed by Alamar Blue, lactate dehydrogenase (LDH), and Live/Dead cell viability/cytotoxicity assays. These studies demonstrate that thermoresponsive PEGMEMA-PPGMA-EGDMA copolymers offer potential as in situ photopolymerizable materials for tissue engineering and drug delivery applications through a combination of facile synthesis, enhanced mechanical properties, tunable cross-linking density, low cytotoxicity, and accessible functionality for further structure modifications.