Electrospun anisotropic fiber reinforced composites for artificial heart valves.

Anisotropic composite valves that approximate natural heart valves are essential for the successful construction of tissue-engineered heart valves. In this work, anisotropic nylon (polyamides, PA) fiber membranes were prepared electrospinning and further composited with thermoplastic polyurethane (TPU) by the impregnation method to obtain anisotropic PA/TPU composite valves. Young's modulus of the PA/TPU composite valves in the axial and radial directions along the fibers was 85.07 ± 4.22 MPa and 28.72 ± 1.16 MPa, respectively. The anisotropic PA/TPU composite valve exhibited excellent anisotropy, and its anisotropy ratio was 3.03, which was close to that of natural valves. Besides, the anisotropic PA/TPU composite valve exhibits high transparency (∼87%). The experiments revealed that anisotropic PA/TPU composite valves have better resistance to calcification and good blood compatibility compared with anisotropic nylon fiber membranes. Moreover, the hydrophilicity presented by the anisotropic PA/TPU composite valve reduced the adhesion of calcified particles. The good anticoagulant properties exhibited by the anisotropic PA/TPU composite valve effectively reduced the formation of thrombus after implantation. Cellular experiments and subcutaneous implantation experiments in rats showed that anisotropic PA/TPU composite valves exhibit cellular nontoxicity and good biocompatibility, contributing to cellular differentiation and growth. This preparation method has great potential in preparing anisotropic composite valves.