Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks

Lucas R. Parent, David Onofrei, Dian Xu, Dillan Stengel, John D. Roehling, J. Bennett Addison, Christopher Forman, Samrat A. Amin, Brian Cherry, Jeffery Yarger, Nathan C. Gianneschi, Gregory P. Holland

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)11507-11512
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number45
DOIs
StatePublished - Nov 6 2018

Keywords

  • Biomimetic materials
  • Hierarchical micelles
  • Natural protein nanostructures
  • Spider silk formation

ASJC Scopus subject areas

  • General

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    Parent, L. R., Onofrei, D., Xu, D., Stengel, D., Roehling, J. D., Bennett Addison, J., Forman, C., Amin, S. A., Cherry, B., Yarger, J., Gianneschi, N. C., & Holland, G. P. (2018). Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks. Proceedings of the National Academy of Sciences of the United States of America, 115(45), 11507-11512. https://doi.org/10.1073/pnas.1810203115