writer：Dang, QQ; Lu, SD; Yu, S; Sun, PC
keywords：Silk fibroin, Nanocomposite, Conformation, Dispersion, NMR
source：期刊
specific source：Biomacromolecules2010, 11, 1796–1801
Issue time：2010年
By adjusting the solution pH value below the isoelectric point (pI) of silk fibroin (SF) protein, the SF was in the cation state and it could interact strongly with unmodified anionic montmorillonite (MMT) surface. In this way, novel SF-MMT nanocomposites with good clay dispersion were successfully obtained, which were confirmed by
X-ray diffraction and transmission electron microscopy. Further 1H CRAMPS and 13C CP/MAS NMR experimental results revealed that
-sheet content of SF was remarkably enhanced for nanocomposite prepared below the pI of  SF (SF-MMTA) due to the strong interaction between MMT and SF. In SF-MMTA nanocomposite, clay layers
acting as an efficient nucleator could efficiently enhance the
-sheet crystallization. On the contrary, SF preserved the native random coil conformation in SF-MMTN nanocomposites due to the weak interaction between MMT and SF. A tentative model was suggested and used to explain the mechanism of clay dispersion and conformational transition of silk protein.