Open AccessLiquid Crystalline Granules Align in a Hierarchical Structure To Produce Spider Dragline Microfibrils
Author(s) -
TingYu Lin,
Hiroyasu Masunaga,
Ryota Sato,
Ali D. Malay,
Kiminori Toyooka,
Takaaki Hikima,
Keiji Numata
Publication year - 2017
Publication title -
biomacromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.689
H-Index - 220
eISSN - 1526-4602
pISSN - 1525-7797
DOI - 10.1021/acs.biomac.7b00086
Subject(s) - silk , materials science , spider silk , spinning , microfibril , chemical engineering , homogeneous , granule (geology) , polymer chemistry , composite material , cellulose , physics , thermodynamics , engineering
The spider silk spinning process converts spidroins from an aqueous form to a tough fiber. This spinning process has been investigated by numerous researchers, and micelles or liquid crystals of spidroins have been reported to form silk fibers, which are bundles of silk microfibrils. However, the formation process of silk microfibrils has not been clarified previously. Here, we report that silk microfibrils are generated through the formation, homogenization, and linkage of liquid crystalline granules without micelle-like structures. Heterogeneous granules on the submicron to micron scale were observed in the storage sac, whereas homogeneous granules with diameters of approximately 100 nm were aligned along the tapering duct. In the spun fibers, the homogeneous granules were connected along the fiber axis. This is the first clear description of the formation of granule-based microfibrils in the spinning process, which is the key conversion process leading to the unique hierarchical structure of spider dragline.