Preparation of regenerated silk fibroin/silk sericin fibers by coaxial electrospinning

The coaxial electrospinning using the regenerated silk fibroin (SF) and silk sericin (SS) aqueous solutions as the core and shell spinning dopes, respectively, was carried out to prepare regenerated SF/SS composite fibers with components and core-shell structure similar to the natural silkworm silks. It was found from the scanning electron microscope (SEM) and transmission electron microscope (TEM) results that the core dope (SF aqueous solution) flow rate (Q(c)) and the applied voltage (V) had some effects on the morphology of the composite fiber. With an increase in Q(c), the diameter nonuniformity and eccentricity of the core fiber became serious, while the increasing V played an inverse role. In this work, the suitable Q(c) for the fiber formation with better electrospinnability was about 6 mu L/min, and the corresponding optimum V was 40 kV. Moreover, the results from Raman spectra analysis, modulated differential scanning calorimetry (MDSC), thermogravimetry (TG) measurement and mechanical property test showed that, compared with the pure SF fiber, the coaxially electrospun SF/SS fiber had more beta-sheet conformation, better thermostability and mechanical properties. This was probably because that SS played significant roles in dehydrating SF molecules and inducing the conformational transition of SF to beta-sheet structure. (C) 2012 Elsevier B.V. All rights reserved.