Electrospun core-sheath fibers for integrating the biocompatibility of silk fibroin and the mechanical properties of PLCL

In the process of preparing core-sheath fibers via coaxial electrospinning, the relative evaporation rates of core and sheath solvents play a key role in the formation of the core-sheath structure of the fiber. Both silk fibroin (SF) and poly(lactide-co-epsilon-caprolactone) (PLCL) have good biocompatibility and biodegradability. SF has better cell affinity than PLCL, whereas PLCL has higher breaking strength and elongation than SF. In this work, hexafluoroisopropanol (HFIP)formic acid (volume ratio 8:2), HFIP and HFIP-dichloromethane (volume ratio 8:2) were used to dissolve PLCL as the core solutions, and HFIP was used to dissolve SF as the sheath solution. Then, core-sheath structured SF/PLCL (C-SF/PLCL) fibers were prepared by coaxial electrospinning with the core and sheath solutions. Transmission electron microscopy images indicated the existence of the core-shell structure of the fibers, and energy dispersive X-ray analysis results revealed that the fiber mat with the greatest content of core-shell structure fibers was obtained when the core solvent was HFIP-dichloromethane (volume ratio 8:2). Tensile tests showed that the C-SF/PLCL fiber mat displayed improved tensile properties, with strength and elongation that were significantly higher than those of the pure SF mat. The C-SF/PLCL fiber mat was further investigated as a scaffold for culturing EA.hy926 cells, and the results showed that the fiber mat permitted cellular adhesion, proliferation and spreading in a manner similar to that of the pure SF fiber mat. These results indicated that the coaxial electrospun SF/PLCL fiber mat could be considered a promising candidate for tissue engineering scaffolds for blood vessels. Copyright (c) 2014 John Wiley & Sons, Ltd.