Development and mechanical characterization of bilayer tubular scaffolds for vascular tissue engineering applications

Poly(l-lactide-co-ε-caprolactone) (PLCL) is a potential material to fabricate scaffolds for vascular tissue engineering. In this work, scaffolds with a multilayered structure comprising a combination of porous and fibrous structures were developed. PLCL was used to fabricate the inner layer of the tubular scaffolds using the freeze-drying technique. The inner layer was then covered by an outer layer fabricated by the melt-spinning technique. The morphology and physical structure of the scaffolds were evaluated through SEM micrographs. The freeze-drying technique formed a porous structure, while the melt-spinning method formed a fibrous structure for the bilayer scaffolds. Physicochemical properties were also investigated by DSC and FTIR measurements; no new functional groups were found to have formed during the freeze-drying or melt-spinning processes. Mechanical properties and fracture mechanism under a tensile loading condition were carefully analyzed to characterize the deformation and fracture behaviors. It was found that the bilayer scaffolds exhibited better mechanical properties than single-layer scaffolds with higher maximum stress at 675.41 kPa, strain at maximum stress at 69.42%, fracture energy at 412.45 kJ/m3 and burst pressure at 147.93 kPa. Porosity, swelling ratio and in vitro biodegradation were measured to ensure its suitability for vascular tissue applications. The bilayer scaffolds with both porous and fibrous structures meet the requirements for vascular tissue engineering.