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Electrospinning solutions containing native silk fibrils with varied diameter and length were firstly achieved by dissolving silk in CaCl2/Formic acid solvents. The structure of nanofibrils significantly improved the spinnability of electrospinning solution. The diameter of electrospun silk fibroin (SF) nanofibers increased from 40 nm to 1.8 μm, which could be achieved through increasing the solution concentration from 2 to 10%, implying a good size control over a wide range in this process. The structure of SF nanofibers transferred from random coil to beta‐sheet, before and after ethanol treatment, respectively. The mechanical properties of the SF nanofibers were improved significantly with stress and strain at break of 11.15 MPa and 7.66% in dry state, and 3.32 MPa and 174.0% in wet state. The strategy for preparing SF nanofibers with improved mechanical properties and fiber diameter control over a wide range provides benefits for the application of this material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41236.

Regenerated silk fibroin films are normally produced by increasing the Silk II structure (β‐sheet content). In the present study, silk fibroin films were prepared by controlling the environmental temperature and humidity, resulting in the formation of silk films with a predominant Silk I structure instead of Silk II structure. Wide angle X‐ray diffraction indicated that when the relative humidity was 55%, the silk films prepared were mainly composed of Silk I structure, whereas silk films formed on other relative humidity had a higher Silk II structure. Fourier transform infrared analysis (FTIR) results also conformed that the secondary structure of silk fibroin can be controlled by changing the humidity of the films formed process. Thermal analysis results revealed Silk I structure was a stable crystal, and the degradation peak increased to 320°C, indicating a greater thermal stability of these films formed under the 55% relative humidity conditions. Atomic force microscopy (AFM) results depicted silk fibroin in the fresh solution had many nanospheres existing with 20–50 nm diameters and mainly maintained a random coil structure without specific nanostructures. At the same time, it also illustrated the self‐assembly process of silk fibroin in the aqueous solution without any human intervention. In addition, this present study also provided additional support for self‐assembly mechanism of silk fibroin films formation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Porous silk fibroin/sodium alginate hybrid scaffolds were prepared through lyophilization method. Hybrid scaffolds were characterized for morphological and functional properties related to different mixture ratios between silk fibroin and sodium alginate. The silk fibroin/sodium alginate hybrid scaffolds showed a thin-layer structure and much more irregular rod-like structure appeared at the layer surface after adding 50% sodium alginate. The results of wide-angle X-ray diffraction and Fourier transform infrared analysis confirmed that the crystal structure of silk fibroin was not influenced by adding the different contents of sodium alginate, exhibiting the random coil structure in the hybrid scaffolds. The thermal behavior of the hybrid scaffolds exhibited major change with containing 30% sodium alginate or more. The porosity of the scaffolds varied between 92 and 94% with a favorable compressive modulus and stress. The mechanical properties results depicted the hybrid scaffolds containing 10% sodium alginate, with a porosity of 94.0 6 0.10%, attained the highest compressive modulus and stress for 41 6 6 and 44 6 3 kPa, respectively. In addition, mineralization results showed hydroxyapatite crystal growing on the surface of the scaffold. This hybrid biomaterial should offer new and important options to the needs related to biomineralization and tissue engineering, in general. POLYM. ENG. SCI., 54:129-136, 2014.

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