Synergy of titanium dioxide nanotubes and polyurethane properties for bypass graft application: Excellent flexibility and biocompatibility

Abstract

A flexible, porous and biocompatible titanium dioxide nanotubes (TNT) - polyurethane (PU) film has been produced as a new scaffold for artificial vascular grafts. Synergistic improvements in the properties of vertical TNT and PU was reached, including enhancements in their biocompatibility, mechanical strength, flexibility and porosity. Open-ended (OE) TNT-PU and close-ended (CE) TNT-PU films were synthesized and their mechanical and biological properties were compared with their pure PU counterparts. TNT were attached to PU with a new strategy. The resulting flexible structure was hydrophilic and super hydrophilic in OE-TNT-PU and CE-TNT-PU scaffolds, respectively. The gas leakage during the attachment of polymers and nanotubes led to an interconnected porous structure of the polymer. The results revealed that the rate of endothelialization of the OE-TNT-PU scaffold vs pure PU scaffolds was 2 times greater after 5 days of in vitro cell culture. In addition, the number of platelets and their agglomeration on the newly designed scaffolds were much lower than those of PU scaffolds. In OE-TNT-PU film, the elongation at break was 881% and the ultimate tensile strength was more than 3 times greater compared to PU. The Young modulus of these scaffolds was greater than150 MPa.

Keywords

• Biomaterials
• Flexible composites
• Polyurethane
• Titanium dioxide nanotubes
• Bypass grafts