Comparative Characterization of Poly(Carbonate-Urethane)-Based Vascular Graft Before and After Preclinical Animal Implantation

Abstract

Three-layered biomimetic vascular grafts (VG) based on poly(carbonate-urethane) (PCU) have been developed and used in clinical trials in China. The durability of PCU and VG during preclinical animal implantation and artificial oxidation tests is of top consideration for the long-term service of implantable devices. After being removed from the sheep after 1 month of implantation, the changes in the microstructures of VG were analyzed and compared using SEM, FTIR, tensile tests, and in situ Wide-angle X-ray diffraction (WAXD) to evaluate the performance of PCU in resisting biodegradation in implantation and blood contact scenarios. Polyester fabrics on the VG could be degraded, while the PCU structures remained largely intact. The micropores on the inner membrane of the VG facilitate endothelialization. During artificial oxidation tests, CoCl₂ and H₂O₂ solution can erode the surface of the hot-pressed film of PCU after 2 weeks of immersion, and the soft segment was partially destroyed by hydrolytic cleavage, which was confirmed by the decrease in the FTIR band at 1256 cm⁻¹. However, the surface deterioration did not lead to a decrease in the tensile strength or elongation at break, even for PCU after four weeks of immersion.