Fabrication and Characterization of Electrospun Thermoplastic Polyurethane/Fibroin Small-Diameter Vascular Grafts for Vascular Tissue Engineering

Abstract The demand for small-diameter blood vessel substitutes has been increasing due to a shortage of autograft vessels and problems with thrombosis and intimal hyperplasia with synthetic grafts. In this study, hybrid small-diameter vascular grafts made of thermoplastic polyurethane (TPU) and silk fibroin, which possessed a hybrid fibrous structure of an aligned inner layer and a random outer layer, were fabricated by the electrospinning technique using a customized striated collector that generated both aligned and random fibers simultaneously. A methanol post-treatment process induced the transition of fibroin protein conformation from the water-soluble, amorphous, and less ordered structures to the water-insoluble β-sheet structures that possessed robust mechanical properties and relatively slow proteolytic degradation. The methanol post-treatment also created crimped fibers that mimicked the wavy structure of collagen fibers in natural blood vessels. Ultrafine nanofibers and nanowebs were found on ...