Bending–Spinning Produces Silkworm and Spider Silk with Enhanced Mechanical Properties

Abstract

Natural silk-spinning behavior endows freshly secreted (FS) silk with a bending angle. This phenomenon is universal among silkworms and spiders but remains unexplained. In this study, the angle of freshly secreted silkworm (FS-S) silk was revealed to be 70.23°–87.93° and that of freshly secreted spider major ampullate (FS-MA) silk to be 0°–50°. Furthermore, the mechanical properties of FS-S silk and FS-MA silk changed after bending, first increasing and then decreasing as the bending angle was increased (0°–360°). The angle corresponding to FS-S silk with the best mechanical properties is 67.5°–90°, and for FS-MA silk, it is 45°. Structural analysis showed that the β-sheet, crystallinity, and crystal size increased with bending angle and the orientation decreased with bending angle. Regular change of microstructure explains the trend for the mechanical property change with bending angle. These findings suggest that bending–spinning produces silkworm and spider silk with enhanced mechanical properties.

Identification and Functions of JHE 6 Specifically Expressed in Bombyx mori Silk Gland

“…Another possibility is that Bmjh6 is involved in the formation of cocoon silk fibrosis because Bmjh6 possesses CO esterase that can cleave esters into acids and alcohols through hydrolysis with the participation of H 2 O. During the process of neutral silk fibroin solution passing through the MSG and ASG from the PSG, it is heavily dehydrated and coagulated owing to the acidic environment of in the MSG and ASG, ultimately completing the cocoon silk fibrosis process [20,21]. Therefore, Bmjhe6 may not only decompose JH in the silk gland, but also participate in the process of cocoon silk fibrosis.…”

“…Silk fibroin secreted by the PSG is secreted into the gland lumen and transported to the MSG. In this region, Silk fibroin is encapsulate by sericin before being secreted out of the body via dehydration and external forces, resulting in silk formation [20,21].…”

Innovations in spider silk‐inspired artificial gel fibers: Methods, properties, strengthening, functionality, and challenges

“…Hence, the reeling and post-stretching processes are instrumental in shaping the spider silk fibers' mechanical properties. In addition, Peng et al 167 described how bending and spinning enhance the mechanical features of spider silk, and the angle associated with the optimal mechanical properties for major-ampullate silk is 45 • . Comparable findings were noted in fibers composed of flexible polymers, where drawing and subsequent post-draw stretching resulted in improved mechanical properties, such as increased tenacity, attributed to enhanced strain alignment.…”

“…Hence, the reeling and post‐stretching processes are instrumental in shaping the spider silk fibers’ mechanical properties. In addition, Peng et al 167 . described how bending and spinning enhance the mechanical features of spider silk, and the angle associated with the optimal mechanical properties for major‐ampullate silk is 45°.…”

Research Progress on Spider‐Inspired Tough Fibers†

“…[ 56 ] Recent research indicates that by altering the micro‐molecular structure, the spinning bending angle can also impact the mechanical characteristics of spider silk. [ 57 ] Therefore, the current state of spider silk production can be improved in line with the modification of spinning circumstances and mechanical machinery.…”