Structure and performance of nano-hydroxyapatite filled biodegradable poly((1,2-propanediol-sebacate)-citrate) elastomers

Novel nano-hydroxyapatite (n-HAp)/poly((1,2-propanediol-sebacate)-citrate) (PPSC) composites, with varying the amount of n-HAp (5-20 wt%), for potential use in the soft tissue engineering were developed in the present work. The structure of composites was characterized by FT-IR and 13C NMR, the micromorphology of n-HAp and the dispersion property of n-HAp in n-HAp/PPSC composites were characterized by SEM and TEM. The experimental results showed that no obvious chemical bonds generated between n-HAp and PPSC matrix. Homogeneous distribution of nanoparticles in the polymer matrix was validated. DSC and DMA indicated that the Tg of the composites decreased with increasing the n-HAp content, as the chemical cross-linking density of the composites decreased. The mechanical properties of the composites were prominently improved, when the amount of n-HAp increased up to 20 wt%, the modulus of the composites increased 11.4 times, and the tensile strength of the composites increased 8.2 times. The hydrophilicity, water absorption, and degradation rate of composites can be tuned through varying the concentration of n-HAp. In vitro cytotoxicity was evaluated by the MTT assay with the L929 cell. The cell relative growth rates of the composites with the amount of n-HAp more than 10 wt% exceeded 75% after 7 days of incubation.