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This paper provides a method combining eco-friendly supercritical CO2 microcellular foaming and polymer leaching to fabricate small-diameter vascular tissue engineering scaffolds.

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Biodegradable ϕ4 mm tubular porous poly(ε-caprolactone)/poly(L-lactide-co-ε-caprolactone) (PCL/PLCL) scaffolds are fabricated successfully via one-step microcellular supercritical carbon dioxide foaming process. The effect of blending ratio on the rheology, pore structures, mechanical property, wettability, and biocompatibility of PCL/PLCL blends tubular scaffold are reported. Rheological results show that PCL matrix and PLCL dispersed phase has good compatibility. The melt strength of PCL can be enhanced obviously by adding PLCL. With an increase of PLCL content from 10 to 30 wt%, the pore size increases from 7.6 to 24.9 μm due to the homogeneous nucleation effect. The maximum open-cell content can reach 77% for PCL/PLCL foamed sample. Cyclical tensile and compliance tests show that few content of dispersed PLCL (10-20 wt%) improves the flexibility and recoverability. Cell viability results demonstrate that human umbilical vein endothelial cells (HUVECs) cultured on all PCL/PLCL porous scaffolds exhibit a typical spindle-like cell morphology. Moreover, HUVECs have a higher density and spreading areas on surface of 10% PLCL scaffold. The results gathered in this paper may open a new perspective for the fabrication of small-diameter vascular tissue engineering scaffold.

The properties of polymeric nanofibers are determined by their internal structure. Although electrospun nanofibers have been widely applied in many fields, their internal structure is still not extensively reported, especially for amorphous nanofibers, which cannot be analyzed by studying the morphology of the crystal lamellar such as the crystalline nanofibers. In this study, the internal structure of electrospun amorphous polycarbonate (PC) nanofibers is investigated. The phase contrast and transmission electron microscopy images show that PC nanofibers exhibit a cylinder‐like structure composed of molecular chains that are highly oriented along the fiber axis. This interesting cylinder‐like internal structure may be the result of evaporation‐induced phase separation in the polymer solution jet and the high strain rate in the electrospinning process. The variation of mechanical properties of PC nanofibers agrees well with the varied internal structure of the nanofibers with different fiber diameters. Due to the high degree of molecular orientation, as‐spun PC nanofibers exhibit superior elastic modulus (6.2 GPa) and strength (780 MPa). The cylinder‐like structure provides an insight into the internal structure of an amorphous electrospun nanofiber, which helps optimize the mechanical performance of amorphous nanofibers and fiber‐based devices.