Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks

Journal Article · Mon Oct 22 00:00:00 EDT 2018 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.1810203115· OSTI ID:1478447

Parent, Lucas R. ^[1]; Onofrei, David ^[2]; Xu, Dian ^[3]; Stengel, Dillan ^[2]; Roehling, John D. ^[4]; Addison, J. Bennett ^[2]; Forman, Christopher ^[1]; Amin, Samrat A. ^[3]; Cherry, Brian R. ^[3]; Yarger, Jeffery L. ^[3]; Gianneschi, Nathan C. ^[1]; Holland, Gregory P. ^[2]

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1. Department of Chemistry, Northwestern University, Evanston, IL 60208,, Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208,, Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208,
2. Department of Chemistry and Biochemistry, San Diego State University (SDSU), San Diego, CA 92182,
3. School of Molecular Sciences, Arizona State University, Tempe, AZ 85287,, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287,
4. Materials Science Division, Lawrence Livermore National Laboratory, Livermore, CA 94551

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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1478447
• Alternate ID(s): OSTI ID: 1488786
• Report Number(s): LLNL-JRNL-748285
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 115 Journal Issue: 45; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of Sciences
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE