In vitro and in vivo degradation behavior of n-HA/PCL-Pluronic-PCL polyurethane composites

Scaffolds for bone tissue engineering applications should have suitable degradability in favor of new bone ingrowth after implantation into bone defects. In this study, degradation behavior of polyurethane composites composed of triblock copolymer poly(caprolactone)-poluronic-poly(caprolactone) (PCL-Pluronic-PCL, PCFC) and nanohydroxyapatite (n-HA) was investigated. The water contact angle and water absorption were measured to reveal the effect of n-HA content on the surface wettability and swelling behavior of the n-HA/PCFC composites, respectively. The weight loss in three degradation media with pH value of 4.0, 7.4, and 9.18 was also studied accordingly. Fourier transform infrared analysis, differential scanning calorimeter, X-ray diffraction, thermal-gravimetric analysis, and scanning electron microscopy were used to investigate the change of chemical structure and micromorphology after the n-HA/PCFC composite with 30% HA was degraded for different time intervals. Meanwhile, in vivo degradation was conducted by subcutaneous implantation. The weight loss and morphology change during observation periods were also studied.