Polyurethanes are microphase separated polymers, containing hard and soft segments. The hard, rigid segments are produced by a reaction between diisocyanate and chain extender while polyether, polyester or polycarbonate diol comprises the soft segments. Hard domains act as reinforcing filler in the soft matrix. The hard segment content influences the degree of the phase separation, which further affects the physical and mechanical properties and biocompatibility. By varying the composition of the polyurethanes their properties can be tuned to use in many areas of tissue engineering, either for reconstruction of soft tissue or for cartilage and bone regeneration.

The objective of this study was to develop polyurethane scaffolds with optimal hard segment content for human osteoblast culture. The aliphatic poly (ester-urethanes) were synthesized from poly(ε-caprolactone) diol with different molecular mass, cycloaliphatic diisocyanate 4, 4’-methylenebis(cyclohexyl isocyanate) and ethylene glycol as a chain extender. The structure-property relationships and behavior of Human Bone Derived Cells (HBDCs) in direct contact with the solid segmented polyurethanes containing from 22 to 70% (w/w) of the hard segments were investigated. Tensile strength and hardness of the polyurethanes were in the range of 1.6 - 48 MPA and 22- 61 Sh D, respectively. Increasing content of the hard segments results in an increasing surface hydrophilicity determined by contact angle measurements. Crystalline phase of polyurethane was characterized by differential scanning calorimetry and chemical structure by infrared spectroscopy. The best biocompatibility of HBDCs cultured in vitro demonstrates polyurethane containing 50% (w/w) of hard segments. This type of polyurethane was selected for porous scaffold fabrication.

Acknowledgements

This work was supported by the Ministry of Science and Higher Education, grant R13 01901.