The effect of terminal globular domains on the response of recombinant mini-spidroins to fiber spinning triggers

AbstractSpider silk spidroins consist of long repetitive protein strands, flanked by globular terminal domains. The globular domains are often omitted in recombinant spidroins, but are thought to be essential for the spiders’ natural spinning process. Mimicking this spinning process could be an essential step towards producing strong synthetic spider silk. Here we describe the production of a range of mini-spidroins with both terminal domains, and characterize their response to a number of biomimetic spinning triggers. Our results suggest that the inclusion of the terminal domains is needed to match the response to shear that native spidroins exhibit. Our results also suggest that a pH drop alone is insufficient to trigger assembly in a wet-spinning process, and must be combined with salting-out for effective fiber formation. With these insights, we applied these assembly triggers for relatively biomimetic wet spinning. This work adds to the foundation of literature for developing improved biomimetic spinning techniques, which ought to result in synthetic silk that more closely approximates the unique properties of native spider silk.

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Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1810203115 ◽

2018 ◽

Vol 115 (45) ◽

pp. 11507-11512 ◽

Cited By ~ 14

Author(s):

Lucas R. Parent ◽

David Onofrei ◽

Dian Xu ◽

Dillan Stengel ◽

John D. Roehling ◽

...

Keyword(s):

Liquid Crystalline ◽

Spider Silk ◽

Fiber Spinning ◽

Fiber Formation ◽

Natural Material ◽

Physical Form ◽

Spinning Process ◽

Black Widow Spiders ◽

Spider Silks

Many natural silks produced by spiders and insects are unique materials in their exceptional toughness and tensile strength, while being lightweight and biodegradable–properties that are currently unparalleled in synthetic materials. Myriad approaches have been attempted to prepare artificial silks from recombinant spider silk spidroins but have each failed to achieve the advantageous properties of the natural material. This is because of an incomplete understanding of the in vivo spidroin-to-fiber spinning process and, particularly, because of a lack of knowledge of the true morphological nature of spidroin nanostructures in the precursor dope solution and the mechanisms by which these nanostructures transform into micrometer-scale silk fibers. Herein we determine the physical form of the natural spidroin precursor nanostructures stored within spider glands that seed the formation of their silks and reveal the fundamental structural transformations that occur during the initial stages of extrusion en route to fiber formation. Using a combination of solution phase diffusion NMR and cryogenic transmission electron microscopy (cryo-TEM), we reveal direct evidence that the concentrated spidroin proteins are stored in the silk glands of black widow spiders as complex, hierarchical nanoassemblies (∼300 nm diameter) that are composed of micellar subdomains, substructures that themselves are engaged in the initial nanoscale transformations that occur in response to shear. We find that the established micelle theory of silk fiber precursor storage is incomplete and that the first steps toward liquid crystalline organization during silk spinning involve the fibrillization of nanoscale hierarchical micelle subdomains.

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Tough synthetic spider-silk fibers obtained by titanium dioxide incorporation and formaldehyde cross-linking in a simple wet-spinning process

Biochimie ◽

10.1016/j.biochi.2020.05.003 ◽

2020 ◽

Vol 175 ◽

pp. 77-84

Author(s):

Hongnian Zhu ◽

Yuan Sun ◽

Tuo Yi ◽

Suyang Wang ◽

Junpeng Mi ◽

...

Keyword(s):

Titanium Dioxide ◽

Spider Silk ◽

Wet Spinning ◽

Cross Linking ◽

Silk Fibers ◽

Spinning Process

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New Approach to Preparation of Heat-Resistant “Lola-M” Fiber

Materials ◽

10.3390/ma12213490 ◽

2019 ◽

Vol 12 (21) ◽

pp. 3490 ◽

Cited By ~ 1

Author(s):

Igor I. Ponomarev ◽

Ivan Y. Skvortsov ◽

Yulia A. Volkova ◽

Ivan I. Ponomarev ◽

Lydia A. Varfolomeeva ◽

...

Keyword(s):

Energy Efficient ◽

Ternary Mixture ◽

Average Diameter ◽

Fiber Spinning ◽

Wet Spinning ◽

New Approach ◽

Elongation At Break ◽

Heat Resistant ◽

Polymer Reaction ◽

Spinning Process

A new approach to the synthesis of polynaphthoylenebenzimidazoles and heat resistant fiber spinning has been developed using an environmentally friendly and energy efficient method, which operates with solutions of pre-polymers based on 3,3’,4,4’-tetraaminodiphenyl ether and 1,4,5,8-naphthalenetetracarboxylic acid dianhydride in N-methylpyrrolidone. Rheological properties of polymer reaction solutions and appropriate coagulant mixtures were investigated for further wet spinning process. The coagulation process was investigated through microscopic observation of solution droplets which imitate jet/fiber cross section surrounded with coagulants of different composition. For the case of the most optimal viscoelastic properties of dopes the best coagulant was found to be a ternary mixture ethanol/water/NMP (20/10/70). Fibers were prepared through the wet spinning from pre-polymers of various molecular weight characterized by intrinsic viscosity. As a result, complex yarns were spun, and their morphology was characterized and mechanical properties were measured. The strength of ~300 MPa and elastic modulus of ~2 GPa and elongation at break of ~20% were reached for the best fibers at average diameter of ~20 µm. After heat treatment “Lola-M” fibers do not burn and do not support combustion in open flame.

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Compositions Based on PAN Solutions Containing Polydimethylsiloxane Additives: Morphology, Rheology, and Fiber Spinning

Polymers ◽

10.3390/polym12040815 ◽

2020 ◽

Vol 12 (4) ◽

pp. 815

Author(s):

Valery G. Kulichikhin ◽

Ivan Y. Skvortsov ◽

Lydia A. Varfolomeeva

Keyword(s):

Phase Separation ◽

Continuous Medium ◽

Viscosity Ratio ◽

Fiber Spinning ◽

Wet Spinning ◽

Diffusion Front ◽

Molecular Weights ◽

Effect Of Additives ◽

Coalescence Rate ◽

Spinning Process

The effect of additives of polydimethylsiloxanes (PDMS) with various molecular weights on the morphology and rheological behavior of polyacrylonitrile (PAN) solutions in dimethyl sulfoxide has been analyzed. It was shown that only partial compatibility of the PDMS with the lowest molecular weight member of the homologous series studied—hexamethyldisiloxane—with PAN solution takes place. All other PDMS samples form emulsions with PAN solutions. The coalescence rate of PDMS drops depends on the viscosity ratio of the disperse phase and the continuous medium, which determines both the duration of dispersion preparation and the conditions for processing emulsions into fibers and films. An anomalous change in viscosity for a series of emulsions with different concentrations of additives, associated with the slippage, was detected. The relaxation properties of emulsions “feel” macro-phase separation. Modeling of the wet spinning process has shown that the morphology of the deposited solution drop reflects the movement of the diffusion front, leading to the gathering droplets in the center of the deposited formulation drop or to their localization in a certain arrangement. It was shown that the emulsion jets upon stretching undergo phase separation.

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Structural Basis of Oligomerization of N-Terminal Domain of Spider Aciniform Silk Protein

International Journal of Molecular Sciences ◽

10.3390/ijms21124466 ◽

2020 ◽

Vol 21 (12) ◽

pp. 4466 ◽

Cited By ~ 1

Author(s):

Rusha Chakraborty ◽

Jing-song Fan ◽

Chong Cheong Lai ◽

Palur Venkata Raghuvamsi ◽

Pin Xuan Chee ◽

...

Keyword(s):

Spider Silk ◽

Homology Modelling ◽

Fiber Formation ◽

Water Soluble ◽

Silk Protein ◽

Structural Basis ◽

Formation Mechanisms ◽

Resonance Spectroscopy ◽

Silk Proteins ◽

Terminal Domains

Spider silk is self-assembled from water-soluble silk proteins through changes in the environment, including pH, salt concentrations, and shear force. The N-terminal domains of major and minor ampullate silk proteins have been found to play an important role in the assembly process through salt- and pH-dependent dimerization. Here, we identified the sequences of the N-terminal domains of aciniform silk protein (AcSpN) and major ampullate silk protein (MaSpN) from Nephila antipodiana (NA). Different from MaSpN, our biophysical characterization indicated that AcSpN assembles to form large oligomers, instead of a dimer, upon condition changes from neutral to acidic pH and/or from a high to low salt concentration. Our structural studies, by nuclear magnetic resonance spectroscopy and homology modelling, revealed that AcSpN and MaSpN monomers adopt similar overall structures, but have very different charge distributions contributing to the differential self-association features. The intermolecular interaction interfaces for AcSp oligomers were identified using hydrogen–deuterium exchange mass spectrometry and mutagenesis. On the basis of the monomeric structure and identified interfaces, the oligomeric structures of AcSpN were modelled. The structural information obtained will facilitate an understanding of silk fiber formation mechanisms for aciniform silk protein.

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Theoretical and experimental investigation of the wet-spinning process for mechanically strong carbon nanotube fibers

Chemical Engineering Journal ◽

10.1016/j.cej.2021.128650 ◽

2021 ◽

Vol 412 ◽

pp. 128650

Author(s):

Hyeon Dam Jeong ◽

Seo Gyun Kim ◽

Gyeong Min Choi ◽

Minji Park ◽

Bon-Cheol Ku ◽

...

Keyword(s):

Experimental Investigation ◽

Carbon Nanotube ◽

Wet Spinning ◽

Spinning Process ◽

Carbon Nanotube Fibers

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Cribellate thread production as model for spider’s spinneret kinematics

Journal of Comparative Physiology A ◽

10.1007/s00359-020-01460-4 ◽

2021 ◽

Author(s):

Margret Weissbach ◽

Marius Neugebauer ◽

Anna-Christin Joel

Keyword(s):

Molecular Structure ◽

Mechanical Properties ◽

Fibre Type ◽

Material Science ◽

Spider Silk ◽

Functional Unit ◽

Material Strength ◽

Spinning Process ◽

Fibre Spinning ◽

House Spider

AbstractSpider silk attracts researchers from the most diverse fields, such as material science or medicine. However, still little is known about silk aside from its molecular structure and material strength. Spiders produce many different silks and even join several silk types to one functional unit. In cribellate spiders, a complex multi-fibre system with up to six different silks affects the adherence to the prey. The assembly of these cribellate capture threads influences the mechanical properties as each fibre type absorbs forces specifically. For the interplay of fibres, spinnerets have to move spatially and come into contact with each other at specific points in time. However, spinneret kinematics are not well described though highly sophisticated movements are performed which are in no way inferior to the movements of other flexible appendages. We describe here the kinematics for the spinnerets involved in the cribellate spinning process of the grey house spider, Badumna longinqua, as an example of spinneret kinematics in general. With this information, we set a basis for understanding spinneret kinematics in other spinning processes of spiders and additionally provide inspiration for biomimetic multiple fibre spinning.

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