Optimization of the structure of polyurethanes for bone tissue engineering applications.

Polyurethanes containing 22-70 wt.% hard segments were developed and evaluated for bone tissue engineering applications. Aliphatic poly(ester-urethanes) were synthesised from poly(epsilon-caprolactone) diol with different molecular masses (M= approximately 530, 1250 and 2000 Da), cycloaliphatic diisocyanate 4,4'-methylenebis(cyclohexyl isocyanate) and ethylene glycol as a chain extender. Changes in macromolecule order with increasing hard segment content were observed via modulated differential scanning calorimetry. Depending on the hard segment content, a gradual variation in polyurethane surface properties was revealed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and static contact angle measurements. As the hard segments content increased the polyurethane surface exhibited more phase separation, a higher content of urethane moieties and higher hydrophilicity. The biocompatibility results indicated that proliferation of human bone-derived cells (HBDC) cultured in vitro improved with increasing hard segment content while the osteogenic potential of HBDC decreased with increasing hard segment content. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.