Synthesis, characterization, and in vitro cell culture viability of degradable poly(N-isopropylacrylamide-co-5,6-benzo-2-methylene-1,3-dioxepane)-based polymers and crosslinked gels

Authors

  • Daniel J. Siegwart,

    1. Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
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  • Sidi A. Bencherif,

    1. Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
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  • Abiraman Srinivasan,

    1. Bone Tissue Engineering Center, 125 Smith Hall, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213
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  • Jeffrey O. Hollinger,

    1. Bone Tissue Engineering Center, 125 Smith Hall, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213
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  • Krzysztof Matyjaszewski

    Corresponding author
    1. Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
    • Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
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Abstract

Poly(N-isopropylacrylamide-co-5,6-benzo-2-methylene-1,3-dioxepane) (poly(NIPAAm-co-BMDO)) was synthesized by atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. Using UV–vis spectroscopy, the lower critical solution temperature (LCST) of poly(NIPAAm) and poly(NIPAAm-co-BMDO) copolymers were measured, varying with respect to the amount of incorporated BMDO. This material is degradable and possesses a LCST above room temperature and below body temperature, making it a potential candidate for use as an injectable tissue engineering scaffold to enhance fracture repair. ATRP and RAFT enabled preparation of polymers with control over molecular weight up to Mn = 50,000 g/mol and Mw/Mn < 1.2. Degradation studies were performed in basic solution and in complete Dulbecco's modified Eagle medium. The cytotoxicity of the material and its degradation products were analyzed by in vitro cell culture analyses, including cytotoxicity live/dead and CyQUANT cell proliferation assays. Crosslinked scaffolds with degradable units within the polymer backbone and at the crosslinking sites were prepared using an ester-containing diacrylate crosslinker. Furthermore, incorporation of a GRGDS peptide sequence improved cell attachment to the gels. Controlled/living radical polymerization techniques allow for precise control over macromolecular structure and are poised to become powerful tools for tissue engineering scaffold synthesis. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008

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