Functionally graded electrospun scaffolds with tunable mechanical properties for vascular tissue regeneration

Abstract

Electrospun tubular scaffolds (4 mm inner diameter) based on bio-artificial blends of polyglyconate (Maxon®) and proteins such as gelatin and elastin having a spatially designed multilayer structure were prepared for use as vascular tissue scaffolds. Scanning electron microscopy analysis of scaffolds showed a random nanofibrous morphology with fiber diameter in the range of 200–400 nm for protein-blended Maxon, which mimics the nanoscale dimensions of collagen (50–500 nm). The scaffolds have a well interconnected pore structure and porosity up to 82%, with protein blending and multi-layering in contrast to electrospun Maxon® scaffolds (67%). Fourier-transform infrared spectroscopy, x-ray diffraction and differential scanning calorimetry results confirmed the blended composition and crystallinity of fibers. Uniaxial tensile testing revealed a strength of 14.46 ± 0.42 MPa and a modulus of 15.44 ± 2.53 MPa with a failure strain of 322.5 ± 10% for a pure Maxon® scaffold. The blending of polyglyconate with biopolymers decreased the tensile properties in general, with an exception of the tensile modulus (48.38 ± 2 MPa) of gelatin/Maxon mesh, which was higher than that of the pure Maxon® scaffold. Trilayered tubular scaffolds of gelatin/elastin, gelatin/elastin/Maxon and gelatin/Maxon (GE-GEM-GM) that mimic the complex trilayer matrix structure of natural artery have been prepared by sequential electrospinning. Tensile testing under dry conditions revealed a tensile strength of 2.71 ± 0.2 MPa and a modulus of 20.4 ± 3 MPa with a failure strain of 140 ± 10%. However, GE-GEM-GM scaffolds tested under wet conditions after soaking in a phosphate buffered saline medium at 37 °C for 24 h exhibited mechanical properties (2.5 MPa tensile strength and 9 MPa tensile modulus) comparable to those of native femoral artery.