Study Of Silk Fibroin/Poly(ε-caprolactone) Blend Nanofibers By Electrospinning

The blend nano-fibers of silk fibroin (Bombyx mori)/poly(ε-caprolactone)(PCL) were prepared by electro-spinning the blending regenerated SF and PCL solution. Trying to use PCL to overcome the defects of the pure electro-spun SF materials with a small fracture elongation, while obtain good biocompatible materials, trying to provide a new material for blood vessels and nervous tissue repairing and a preparation for follow-up study of the application.The silk films which were prepared by casting SF solution on a polyethylene plate and PCL were mixed according to different proportions dissolved in hexafluoro- isopropanol (HFIP), using self-designed electro-spinning device spun blending nano-fibers. The morphology changed with different content of PCL, solution concentration, voltage, distance and the flow rate of the solution of collected SF fiber mats were observed using scanning electron microscope (SEM). The fiber diameter and its distribution were observed, as well as the morphological changes of regeneration of SF/PCL nano-fiber after ethanol treatment. The results showed that the solution become viscous with the increase of PCL content, while the jet with high concentration wasn't fully differentiation, so the fiber diameter gradually increase thicken. The regenerated SF / PCL nano-fiber diameter increases with the concentration of mixed solution increase. The fibers dry thoroughly, when the flow rate of the solution was less than l.5ml/h. With the voltage increasing to 15 kV the fiber becomes uniform, when the distance between the syringe tip and the collecting target was less than 10 cm, many beaded fibers and droplet appeared due to solvent not fully evaporation, in the contrary the distance become too larger more than 12 cm and the diameter increase. When the SF/PCL blend ratio is 70:30, the concentration 6 wt%, voltage 15 kV, distance 10 cm, it can get uniform fibers and the average diameter was about 450 nm.The conformational structure of blend nano-fibers was characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy and DTG. The water solubility, broken tensile strength of blend nano-fibers were tested and analyzed. XRD curve didn't appear new crystallization peak. FT-IR and RS spectra indicated that the absorption peaks showed a certain offset with the PCL content increase, especially at 50% content, while the rate of heat loss also confirmed that blend nano-fibers were almost insoluble. PCL possesses high tensile and elongation properties, so the flexibility and elongation at break of blend nano-fibers had improved. The elongation at break increased from 44.94% to 150.25% with the content of PCL increased. After ethanol treatment, the conformation of silk changed from silkⅠto silkⅡ, and the tensile strength increased, while the elongation at break increased slightly.The results indicated that: the SF / PCL materials which were prepared by blending methods have good elongation at break. PCL can significantly overcome the shortcomings of low elongation at break of the pure SF materials. When the SF / PCL blending ratio was 70:30, the breaking elongation rate has reached 100%. The blending materials provide a potential candidate for tissue engineering scaffold.