Journal of Nanoparticle Research

, Volume 9, Issue 5, pp 885–900 | Cite as

Formation of silk fibroin nanoparticles in water-miscible organic solvent and their characterization

  • Yu-Qing ZhangEmail author
  • Wei-De Shen
  • Ru-Li Xiang
  • Lan-Jian Zhuge
  • Wei-Jian Gao
  • Wen-Bao Wang


When Silk fibre derived from Bombyx mori, a native biopolymer, was dissolved in highly concentrated neutral salts such as CaCl2, the regenerated liquid silk, a gradually degraded peptide mixture of silk fibroin, could be obtained. The silk fibroin nanoparticles were prepared rapidly from the liquid silk by using water-miscible protonic and polar aprotonic organic solvents. The nanoparticles are insoluble but well dispersed and stable in aqueous solution and are globular particles with a range of 35–125 nm in diameter by means of TEM, SEM, AFM and laser sizer. Over one half of the ɛ-amino groups exist around the protein nanoparticles by using a trinitrobenzenesulfonic acid (TNBS) method. Raman spectra shows the tyrosine residues on the surface of the globules are more exposed than those on native silk fibers. The crystalline polymorph and conformation transition of the silk nanoparticles from random-coil and α-helix form (Silk I) into anti-parallel β-sheet form (Silk II) are investigated in detail by using infrared, fluorescence and Raman spectroscopy, DSC, 13C CP-MAS NMR and electron diffraction. X-ray diffraction of the silk nanoparticles shows that the nanoparticles crystallinity is about four fifths of the native fiber. Our results indicate that the degraded peptide chains of the regenerated silk is gathered homogeneously or heterogeneously to form a looser globular structure in aqueous solution. When introduced into excessive organic solvent, the looser globules of the liquid silk are rapidly dispersed and simultaneously dehydrated internally and externally, resulting in the further chain–chain contact, arrangement of those hydrophobic domains inside the globules and final formation of crystalline silk nanoparticles with β-sheet configuration. The morphology and size of the nanoparticles are relative to the kinds, properties and even molecular structures of organic solvents, and more significantly to the looser globular substructure of the degraded silk fibroin in aqueous solution. It is possible that the silk protein nanoparticles are potentially useful in biomaterials such as cosmetics, anti-UV skincare products, industrial materials and surface improving materials, especially in enzyme/drug delivery system as vehicle.


silk fibroin nanoparticles organic solvents biomaterials drug delivery colloids 


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We are grateful to Associate Professor Wang-Fang Shen for her help in the preparation of this manuscript. This work was partly supported by the National Basic Research Program of China (2005CB121000), the University Natural Science Funds of Jiangsu Province (04KJB180122) and Natural Science Funds of Jiangsu Province (BK2006053), P. R. China


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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Yu-Qing Zhang
    • 1
    Email author
  • Wei-De Shen
    • 1
  • Ru-Li Xiang
    • 1
  • Lan-Jian Zhuge
    • 2
  • Wei-Jian Gao
    • 2
  • Wen-Bao Wang
    • 2
  1. 1.Silk Biotechnol. Lab., School of Life ScienceSoochow University702-303 Room, No. 1 Hengyi Road, Dushuhu Higher Education Town, Suzhou, 215123P.R. China
  2. 2.Analytical CenterSoochow UniversitySuzhouP.R. China

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