Emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers

Abstract

The conditions required for the emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers are assessed through an experimental approach that combines the spinning of regenerated fibers with controlled properties and their characterization by 13C solid-state nuclear magnetic resonance (NMR). Both supercontracting and non-supercontracting regenerated fibers are produced using the straining flow spinning (SFS) technique from 13C labeled cocoons. The short-range microstructure of the fibers is assessed through 13C CP/MAS in air and 13C DD/MAS in water, and the main microstructural features are identified and quantified. The mechanical properties of the regenerated fibers and their microstructures are compared with those of natural silkworm silk. The combined analysis highlights two possible key elements as responsible for the emergence of supercontraction: (1) the existence of an upper and a lower limit of the amorphous phase compatible with supercontraction, and (2) the existence of two ordered phases, β-sheet A and B, which correspond to different packing arrangements of the protein chains.

Tensegrity Modelling and the High Toughness of Spider Dragline Silk

“…Here, is the volume fraction of β-sheet crystals. The yielding of the tendons is assumed to occur when the local engineering strain reaches a threshold value The incremental response the post-yielding regime, up to tensile failure, is described by a reduced tangent elastic modulus < [ 32 ] ( Figure 2 C).…”

“…The true stress is instead obtained by dividing the total pulling force by the deformed cross section area . Finally, the true strain is linked to through the equation: [ 32 ].…”

Microstructure Transitions and Dry-Wet Spinnability of Silk Fibroin Protein from Waste Silk Quilt

“…By simulating the spinning method of silkworms, people have expected to prepare superior regenerated silk fibroin fibers with an adjustable morphology and specific structure; further exploring the forming process and mechanisms of natural silk fibers could also promote significant development in the field of silk fibroin materials. Nevertheless, the performance of regenerated silk fibroin fibers developed based on current technical methods is still no match for that of natural silk fibroin fibers [10,11,12]. The relevant research on bionic protein fibers shows the importance of studying the relationship between protein conformation and function and the mechanism of the conformation transformation.…”

Structural investigations of polyurethane and silk‐polyurethane composite fiber studied by 13C solid‐state NMR spectroscopy

“…We have used these chemical shift data to monitor the conformation and also packing states of SF chains. [52][53][54][55][56] Namely, Ala carbon chemical shifts of SF give a good indicator of the conformation, that is, 19.6 and 21.7 ppm (Ala Cβ), 48.9 ppm (Ala Cα) and 172.0 ppm (Ala C O), respectively, for anti-parallel (AP) β-sheet structure, and 16.8 ppm (Ala Cβ), 50.0 ppm (Ala Cα) and 175.5 ppm (Ala C O), respectively, for random coil conformation. 52,53 Thus, the conformation of the regenerated SF fiber without PU1 prepared by the device wet spinning method is concluded to be mainly AP β-sheet structure (Figure 7(a)).…”