Cryogenic toughness of natural silk and a proposed structure–function relationship

Fu, Chengjie; Wang, Yushu; Guan, Juan; Chen, Xin; Vollrath, Fritz; Shao, Zhengzhong

doi:10.1039/c9qm00282k

Cited by 25 publications

(35 citation statements)

References 46 publications

(64 reference statements)

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“…One observes that it results in

at the centre of the fibre (

, and

at the boundary of the fibre’s core

). The assumption of a piecewise constant distribution of

with the radial coordinate allows us to simplify the packing of the fibrils across the fibre; while the assumed piecewise linear variation of

with

leads us to capture the crack deflection effect between adjacent grains [ 6 ]. We also neglect the load carrying capacity of the matrix in between the fibrils material [ 6 , 36 ].…”

Section: Tensegrity Modellingmentioning

confidence: 99%

“…Our proposed tensegrity model not only replicates Poisson’s effect under longitudinal stretching [ 12 , 13 , 14 ], but also accurately reproduces the experimental stress vs. strain response of the fibre under tensile loading and captures the enhanced toughness of the material through crack-deflection [ 6 ] and crack-stopper [ 21 ] mechanisms. The given model relates such mechanisms to regional-dependent deformation modes of the fibrils, and scale effects for the fibrils’ ductility [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

“…It is generally accepted that the remarkable mechanical performance of spider silk dragline originates from a hierarchical organization of proteins into a hydrogen bonded structure of ordered crystalline β-sheets, embedded in a disordered amorphous matrix [ 1 , 2 , 3 , 4 , 5 , 6 ]. However, at the mesoscale, it has also been shown that silk assembles into nanofibrils with diameters ranging from ~30 nm [ 3 ] to more than 100 nm [ 2 , 5 ] and that a fibre has structurally and functionally distinct regions; a load bearing core (consisting of inner (1800–2300 nm), and outer (300–400 nm) sections [ 2 , 7 , 8 ]) surrounded by protective lipid (10–20 nm), glycol (40–100 nm), and skin (50–100 nm) layers [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Whilst there have been several concerted modelling efforts to relate silk’s structures to its mechanical properties [ 3 , 4 , 5 , 6 , 7 , 8 , 18 , 19 ], accounting for the precise contributions of each of these structural elements on a fibre’s mechanical response has been inconclusive. Consider, e.g., the role played by the interfaces between the fibrils, which some studies define as mechanically weak and responsible for easy slippage of adjacent fibrils [ 6 ], while other studies observe the presence of heterogeneous protrusions along such surfaces determining a non-slip kinematics and energy dissipation due to interlocking effects [ 20 ]. In addition, while the literature to-date is populated by a number of multiscale and hierarchical approaches to the mechanics of the dragline silk [ 1 , 2 , 3 , 4 , 5 , 6 , 18 ], and there is experimental evidence of the partitioning of the spider silk fibres into layers with different mechanical behaviours [ 7 , 8 ], one observes that the grading of the mechanical properties along the radial coordinate of silk fibres has not been extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

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Tensegrity Modelling and the High Toughness of Spider Dragline Silk

et al. 2020

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This work establishes a tensegrity model of spider dragline silk. Tensegrity systems are ubiquitous in nature, being able to capture the mechanics of biological shapes through simple and effective modes of deformation via extension and contraction. Guided by quantitative microstructural characterization via air plasma etching and low voltage scanning electron microscopy, we report that this model is able to capture experimentally observed phenomena such as the Poisson effect, tensile stress-strain response, and fibre toughness. This is achieved by accounting for spider silks’ hierarchical organization into microfibrils with radially variable properties. Each fibril is described as a chain of polypeptide tensegrity units formed by crystalline granules operating under compression, which are connected to each other by amorphous links acting under tension. Our results demonstrate, for the first time, that a radial variability in the ductility of tensegrity chains is responsible for high fibre toughness, a defining and desirable feature of spider silk. Based on this model, a discussion about the use of graded tensegrity structures for the optimal design of next-generation biomimetic fibres is presented.

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“…One observes that it results in

at the centre of the fibre (

, and

at the boundary of the fibre’s core

). The assumption of a piecewise constant distribution of

with the radial coordinate allows us to simplify the packing of the fibrils across the fibre; while the assumed piecewise linear variation of

with

leads us to capture the crack deflection effect between adjacent grains [ 6 ]. We also neglect the load carrying capacity of the matrix in between the fibrils material [ 6 , 36 ].…”

Section: Tensegrity Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tensegrity Modelling and the High Toughness of Spider Dragline Silk

et al. 2020

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Bioengineered Protein Fibers with Anti‐Freezing Mechanical Behaviors

Zhang

Sun

et al. 2022

Adv Funct Materials

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Most biological protein fibers exhibit extraordinary mechanical performance at room temperatures but inferior freezing resistance. Maintaining fiber's high strength and toughness under subzero conditions remains a great challenge. Herein, a class of freezing tolerant protein fibers is reported with favorable ice-phobic capacity and cryogenic mechanical performance by genetic engineering. Inspired by nature, chimeric recombinant proteins consist of highly ordered structural protein domains and antifreeze protein (AFP) modules, showing excellent ice recrystallization inhibition activity. Such features endow the resulting protein fibers with remarkable mechanical properties and good mechanical stability in subzero environments. In stark contrast to conventional fibers, the engineered protein fibers maintain high cryogenic stiffness and toughness even at −20 and −40 °C. The synergistic contribution of structural protein and AFP plays an important role for the extraordinary anti-freezing mechanical behaviors. Thus, this study pioneers an engineering approach for the next generation of biological fibers with tailored applications in extreme settings.

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Hierarchically Structured Bioinspired Fibers Shaped by Liquid Droplets

Liu,

Zhang,

2023

Adv Funct Materials

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Nature has a remarkable ability to create multifunctional fibers, such as spider silk, by precisely controlling structures across various scales. However, replicating this in high‐speed spun synthetic fibers is challenging due to the absence of life‐specific forces and interactions required for manipulating composition, gradients, and structures. Here, a novel droplet‐coupled pultrusion spinning technique is demonstrated for industrial‐scale production of microfibers with hierarchical structures. Droplets spontaneously form on the surface of high‐speed spun fibers to tailor multiscale hierarchical structures, resulting in a nonlinear viscoelastic core embedded with anharmonic nanosprings consisting of amorphous and crystalline domains and a periodically reinforced nanofiber skin. These structural hierarchies enable unique mechanical property combinations including nonlinear viscoelasticity, large extensibility (613%), record‐high toughness (536 MJ m−3), highly efficient impact energy absorption, vibration damping and wide temperature adaptability (−67.4 to 278.9 °C). Additionally, the structured bioinspired fibers exhibit low‐frequency phononic bandgap and anomalous dispersion of mechanical waves. The droplet‐based approach allows precise control over heterogeneity at multiple scales within the identical components leading to impressive mechanical performance and additional functionalities, and is consider that it could be applied to the design of the next era of hierarchically structured nanocomposites for a wide range of applications.

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Cryogenic toughness of natural silk and a proposed structure–function relationship

Abstract: A highly aligned and relatively independent nanofibril structure contributes to the cryogenic toughness of natural silk.

Cited by 25 publications

References 46 publications

Tensegrity Modelling and the High Toughness of Spider Dragline Silk

Tensegrity Modelling and the High Toughness of Spider Dragline Silk

Bioengineered Protein Fibers with Anti‐Freezing Mechanical Behaviors

Hierarchically Structured Bioinspired Fibers Shaped by Liquid Droplets

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