A simple process for dry spinning of regenerated silk fibroin aqueous solution


The conventional process for preparing dry spinnable regenerated silk fibroin (RSF) aqueous solution needs not only an addition of Ca2+ but also an adjustment of pH value. In this work, an RSF dry spinning dope was prepared by using a simplified method with solely adding Ca2+. Compared with the conventional RSF solution, the simply prepared aqueous solution showed similar content of β-sheet conformation and diameter of RSF aggregates but lower viscosity. Furthermore, the posttreated RSF fiber dry-spun from this simply prepared solution showed higher crystallinity and crystalline orientation, smaller crystallite size, and better mechanical properties. It could be concluded that Ca2+ played a much more important role than pH value in improving the structures and properties of RSF spinning solution and fibers. Therefore, the step of adjusting pH value could be excluded in the process of preparing high performance RSF fibers.

This is a preview of subscription content, access via your institution.

We’re sorry, something doesn't seem to be working properly.

Please try refreshing the page. If that doesn't work, please contact support so we can address the problem.

FIG. 1.
FIG. 2.
FIG. 3.
FIG. 4.
FIG. 5.
FIG. 6.


  1. 1.

    Z.Z. Shao and F. Vollrath: Surprising strength of silkworm silk. Nature 418, 741 (2002).

    CAS  Article  Google Scholar 

  2. 2.

    C. Vepari and D.L. Kaplan: Silk as a biomaterial. Prog. Polym. Sci. 32, 991 (2007).

    CAS  Article  Google Scholar 

  3. 3.

    R. Kanekatsu: New regenerated fibers composed of silk fibroins and cellulose. Sen-I Gakkaishi 60, 21 (2004).

    Article  Google Scholar 

  4. 4.

    G.Q. Zhou, X. Chen, and Z.Z. Shao: The artificial spinning based on silk proteins. Prog. Chem. 18, 933 (2006).

    CAS  Google Scholar 

  5. 5.

    Y. Kawahara, A. Nakayama, N. Matsumura, T. Yoshioka, and M. Tsuji: Structure for electro-spun silk fibroin nanofibers. J. Appl. Polym. Sci. 107, 3681 (2008).

    CAS  Article  Google Scholar 

  6. 6.

    K. Matsumoto, H. Uejima, T. Iwasaki, Y. Sano, and H.J. Sumino: Studies on regenerated protein fibers. 3. Production of regenerated silk fibroin fiber by the self-dialyzing wet spinning method. J. Appl. Polym. Sci. 60, 503 (1996).

    CAS  Article  Google Scholar 

  7. 7.

    I.C. Um, H.Y. Kweon, K.G. Lee, D.W. Ihm, J.H. Lee, and Y.H. Park: Wet spinning of silk polymer—I. Effect of coagulation conditions on the morphological feature of filament. Int. J. Biol. Macromol. 34, 89 (2004).

    CAS  Article  Google Scholar 

  8. 8.

    I.C. Um, H.Y. Kweon, K.G. Lee, D.W. Ihm, J.H. Lee, and Y.H. Park: Wet spinning of silk polymer—II. Effect of drawing on the structural characteristics and properties of filament. Int. J. Biol. Macromol. 34, 107 (2004).

    CAS  Article  Google Scholar 

  9. 9.

    G.Q. Zhou, Z.Z. Shao, D.P. Knight, J.P. Yan, and X. Chen: Silk fibers extruded artificially from aqueous solutions of regenerated Bombyx mori silk fibroin are tougher than their natural counterparts. Adv. Mater. 20, 1 (2008).

    Article  Google Scholar 

  10. 10.

    J.X. Zhu, Y.P. Zhang, H.L. Shao, and X.C. Hu: Electrospinning and rheology of regenerated Bombyx mori silk fibroin aqueous solutions: The effects of pH and concentration. Polymer 49, 2880 (2008).

    CAS  Article  Google Scholar 

  11. 11.

    W. Wei, Y.P. Zhang, H.L. Shao, and X.C. Hu: Posttreatment of the dry-spun fibers obtained from regenerated silk fibroin aqueous solution in ethanol aqueous solution. J. Mater. Res. 26, 1100 (2011).

    CAS  Article  Google Scholar 

  12. 12.

    W. Wei, Y.P. Zhang, Y.M. Zhao, H.L. Shao, and X.C. Hu: Studies on the post-treatment of the dry-spun fibers from regenerated silk fibroin solution: Post-treatment agent and method. Mater. Des. 36, 816 (2012).

    CAS  Article  Google Scholar 

  13. 13.

    W. Wei, Y.P. Zhang, Y.M. Zhao, H.L. Shao, and X.C. Hu: Bio-inspired capillary dry spinning of regenerated silk fibroin aqueous solution. Mater. Sci. Eng., C 31, 1602 (2011).

    CAS  Article  Google Scholar 

  14. 14.

    M.J. Sun, Y.P. Zhang, Y.M. Zhao, J. Luo, H.L. Shao, and X.C. Hu: The structure–property relationships of artificial silk fabricated by dry-spinning process. J. Mater. Chem. 22, 18372 (2012).

    CAS  Article  Google Scholar 

  15. 15.

    L. Zhou, X. Chen, Z.Z. Shao, Y.F. Huang, and D.P. Knight: Effect of metallic ions on silk formation the mulberry silkworm, Bombyx mori. J. Phys. Chem. B 109, 16937 (2005).

    CAS  Article  Google Scholar 

  16. 16.

    A. Glisovic and T.J. Salditt: Temperature dependent structure of spider silk by X-ray diffraction. Appl. Phys. A 87, 63 (2007).

    CAS  Article  Google Scholar 

  17. 17.

    Y. Shen, M.A. Johnson, and D.C. Martin: Microstructural characterization of Bombyx mori silk fibers. Macromolecules 31, 8857 (1998).

    CAS  Article  Google Scholar 

  18. 18.

    C.W.P. Foo, E. Bini, J. Hensman, D.P. Knight, R.V. Lewis, and D.L. Kaplan: Role of pH and charge on silk protein assembly in insects and spiders. Appl. Phys. A 82, 223 (2006).

    CAS  Article  Google Scholar 

  19. 19.

    J.Z. Shao, J.H. Zheng, J.Q. Liu, and C.M. Carr: Fourier transform Raman and Fourier transform infrared spectroscopy studies of silk fibroin. J. Appl. Polym. Sci. 96, 1999 (2005).

    CAS  Article  Google Scholar 

  20. 20.

    P. Monti, G. Freddi, A. Bertoluzza, N. Kasai, and M. Tsukada: Raman spectroscopic studies of silk fibroin from Bombyx mori. J. Raman Spectrosc. 29, 297 (1998).

    CAS  Article  Google Scholar 

  21. 21.

    P. Zhou, X. Xie, F. Deng, Z. Ping, X. Xun, and D. Feng: Effects of pH and calcium ions on the conformational transitions in silk fibroin using 2D Raman correlation spectroscopy and C-13 solid-state NMR. Biochemistry 43, 11302 (2004).

    CAS  Article  Google Scholar 

  22. 22.

    A. Nagano, H. Sato, Y. Tanioka, Y. Nakazawa, D. Knight, and T. Asakura: Characterization of a Ca binding-amphipathic silk-like protein and peptide with the sequence (Glu)(8)(Ala-Gly-Ser-Gly-Ala-Gly)(4) with potential for bone repair. Soft Matter 8, 741 (2012).

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Huili Shao.

Additional information

Address all correspondence to this author.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Jin, Y., Zhang, Y., Hang, Y. et al. A simple process for dry spinning of regenerated silk fibroin aqueous solution. Journal of Materials Research 28, 2897–2902 (2013). https://doi.org/10.1557/jmr.2013.276

Download citation