X-ray diffraction study of nanocrystalline and amorphous structure within major and minor ampullate dragline spider silks

Sampath, Sujatha; Isdebski, Thomas; Jenkins, Janelle E.; Ayon, Joel; Henning, Robert; Orgel, Joseph P. R. O.; Antipoa, Olga; Yarger, Jeffery L.

doi:10.1039/c2sm25373a

Cited by 120 publications

(191 citation statements)

References 47 publications

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“…Figure 3b shows that the diffusion halo in Figure 3a turns into two dependent diffusion rings, and the corresponding one dimension diffracto-gram illustrated in Figure 3g shows two obvious diffraction peaks at the location of the (120-reflection plane with d = 4.36 Angstroms) and the (211-reflection plane with d = 3.73 Angstroms). These data are in harmony with those obtained for spider dragline silk by Sampath et al [32]. One can attribute the improvement of RSDSs properties to the homogeneity of crystal structure occurred by drying treatment and longitudinal mechanical stresses.…”

Section: Structure Of Recombinant-spider Dragline Silkssupporting

confidence: 77%

“…This crystalline formation is confirmed from data on Figure 3d and 3f where crystalline domains were directed longitudinally through the RSDS after the mechanical stretching treatment. In addition, one can notice the presence of semi-crystalline structure with nano crystallites inlayed through the amorphous regions [32]. spider dragline silk have the fibrillary structure.…”

Section: Structure Of Recombinant-spider Dragline Silksmentioning

confidence: 99%

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Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques

Abdalla¹,

Obaid²,

Al-Marzouki³

et al. 2017

J Material Sci Eng

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Spider silk (SS) is naturally tough; however, it turns soft when wet by water. Spiders produce high-quality silk threads by adjusting the molecular assemblage of SS-proteins and the arrangements structure of threads and recombinant spider dragline silk (RSDS). The general wet spinning techniques for producing recombinant spidroins results in uncorrected explanation to the natural spinning technique. In this study, we use tailored-SS with relative low molecular weight of 47 kD to produce a water-soluble RSDS protein. We built a microfluidic ship and used it to spun SS using aqueous solutions-micro-technique (wet spinning). This was done in order to mimic the spider-spinning processes using a steady post-spin drawing process. We succeeded to produce assemblies of spidroins with fibril structure. Then, compact constituting of micro-threads followed these wet spinning processes. Wet spinning was followed by improving the orientation, crystalline structure, and fibril melting of the hierarchical structure. The initial mechanical characterization (tensile strength) of the RSDSs attained about 510 MPa with respective extension 44%.

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Section: Structure Of Recombinant-spider Dragline Silkssupporting

confidence: 77%

Section: Structure Of Recombinant-spider Dragline Silksmentioning

confidence: 99%

Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques

Abdalla¹,

Obaid²,

Al-Marzouki³

et al. 2017

J Material Sci Eng

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show abstract

“…Analysis by solid state NMR spectroscopy or Raman microspectroscopy suggests levels of 30 -40%, [29][30][31] as opposed to about 20% identified by XRD. 32 Computer simulations of the crystalline components of silk suggest that the poly-alanine sections align anti-parallel in the H-bonding direction with parallel stacking in the side-chain direction to stabilize the β-sheets. 33,34 The high strength of silk materials is mainly attributed to the nanoconfined crystals (4-6 nm), while the breaking elongation is mainly attributed to the unfolding amorphous region.…”

Section: Silk Structure After Spinningmentioning

confidence: 99%

Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly

2016

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Spiders spin their silk from an aqueous solution to a solid fiber in ambient conditions. However, to date the assembly mechanism in the spider silk gland has not been satisfactorily explained. In this paper, we use molecular dynamics simulations to model N. clavipes MaSp1 dragline silk formation under shear flow and determine the secondary structure transitions leading to the experimentally observed fiber structures. While no experiments are performed on the silk fiber itself, insights from this polypeptide model can be transferred to the fiber scale. The novelty of this study lies in the calculation of the shear stress (300-700 MPa) required for fiber formation and identification of the amino acid residues involved in the transition. This is the first time that the shear stress has been quantified in connection with a secondary structure transition. By study of molecules containing varying numbers of contiguous MaSp1 repeats we identified the smallest molecule size that gives rise to a 'silk-like' structure contains six poly-alanine repeats.Through a probability analysis of the secondary structure we identify specific amino acids that transition from α-helix to β-sheet. In addition to portions of the poly-alanine section these amino acids include glycine, leucine and glutamine. Stability of β-sheet structures appears to arise from a close proximity in space of helices in the initial spidroin state. Our results are in agreement with the forces exerted by spiders in the silking process and the experimentally determined global secondary structure of spidroin and pulled MaSp1 silk. Our study emphasizes the role of shear in the assembly process of silk and can guide the design of microfluidic devices that attempt to mimic the natural spinning process and predict molecular requirements for the next generation of silk-based functional materials.

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“…To date, computational calculations 4 , X-ray diffraction 5 , nuclear magnetic resonance 6 , polarized light microscopy 7 , scanning electron microscopy 7,8 , transmission electron microscopy 9 , Raman spectromicroscopy 10 and, more recently, atomic force microscopy (AFM) [11][12][13][14][15][16][17] have been the most commonly used techniques to study the nanoarrangements of silk fibre domains. However, the details of the size, topology, mechanical features and fractional composition of the crystalline and amorphous domains remain to be clarified.…”

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confidence: 99%

Unravelling the biodiversity of nanoscale signatures of spider silk fibres

Silva

Rech

2013

Nat Commun

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Living organisms are masters at designing outstanding self-assembled nanostructures through a hierarchical organization of modular proteins. Protein-based biopolymers improved and selected by the driving forces of molecular evolution are among the most impressive archetypes of nanomaterials. One of these biomacromolecules is the myriad of compound fibroins of spider silks, which combine surprisingly high tensile strength with great elasticity. However, no consensus on the nano-organization of spider silk fibres has been reached. Here we explore the biodiversity of spider silk fibres, focusing on nanoscale characterization with high-resolution atomic force microscopy. Our results reveal an evolution of the nanoroughness, nanostiffness, nanoviscoelastic, nanotribological and nanoelectric organization of microfibres, even when they share similar sizes and shapes. These features are related to unique aspects of their molecular structures. The results show that combined nanoscale analyses of spider silks may enable the screening of appropriate motifs for bioengineering synthetic fibres from recombinant proteins.

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X-ray diffraction study of nanocrystalline and amorphous structure within major and minor ampullate dragline spider silks

Cited by 120 publications

References 47 publications

Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques

Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques

Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly

Unravelling the biodiversity of nanoscale signatures of spider silk fibres

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