In situ synthesized TiO-polyurethane nanocomposite for bypass graft application: In vitro endothelialization and degradation.

The in vitro endothelial response of human umbilical vein endothelial cells was investigated on a poly (caprolactone)-based polyurethane surface vs an in situ TiO-polyurethane nanocomposite surface, which has been produced as scaffolds for artificial vascular graft. The in situ synthesis of TiO nanoparticles in polyurethane provided surface properties that facilitated cellular adhesion, cell sensing, cell probing and especially cell migration. Cells on the nanocomposite surface have elongated morphology and were able to produce more extracellular matrix. All of these advantages led to an increase in the rate of endothelialization of the nanocomposite scaffold surface vs pure polyurethane. The presence of TiO nanoparticles with very good distribution in polyurethane increased the degradability of the scaffolds by increasing the phase separation and hydrophilicity in the nanocomposite film. The results showed that the degradation mechanism of nanocomposite films prompted the interconnectivity of spaces inside structures that probably could give extra chances to improve migration and proliferation of cells, as well as, the delivery of nutrients and metabolites inside the pores of the scaffold. The outcomes revealed that the rate of endothelialization of the nanocomposite scaffold after 7 days of in vitro cell culture was 1.5 times and the rate of degradation of the nanocomposite film was 2 times after 8 weeks of immersion scaffolds in PBS compared to the polyurethane scaffolds. In addition, the nanocomposite scaffold possessed good mechanical properties. Despite its high modulus, it was flexible with a 500% elongation at break.