scholarly journals Photoreflectance/scattering measurements of spider silks informed by standard optics

2020 ◽  
Vol 7 (4) ◽  
pp. 192174
Author(s):  
Sean J. Blamires ◽  
Douglas J. Little ◽  
Thomas E. White ◽  
Deb M. Kane
Keyword(s):  
Optical Properties ◽  
Optical Materials ◽  
Spider Silk ◽  
Nephila Clavipes ◽  
Optical Elements ◽  
Scattering Spectrum ◽  
Modern Species ◽  
Uv Reflectance ◽  
Argiope Keyserlingi ◽  
Spider Silks

The silks of certain orb weaving spiders are emerging as high-quality optical materials. This motivates study of the optical properties of such silk and particularly the comparative optical properties of the silks of different species. Any differences in optical properties may impart biological advantage for a spider species and make the silks interesting for biomimetic prospecting as optical materials. A prior study of the reflectance of spider silks from 18 species reported results for three species of modern orb weaving spiders ( Nephila clavipes, Argiope argentata and Micrathena Schreibersi ) as having reduced reflectance in the UV range. (Modern in the context used here means more recently derived.) The reduced UV reflectance was interpreted as an adaptive advantage in making the silks less visible to insects. Herein, a standard, experimental technique for measuring the reflectance spectrum of diffuse surfaces, using commercially available equipment, has been applied to samples of the silks of four modern species of orb weaving spiders: Phonognatha graeffei , Eriophora transmarina , Nephila plumipes and Argiope keyserlingi . This is a different technique than used in the previous study. Three of the four silks measured have a reduced signal in the UV. By taking the form of the silks as optical elements into account, it is shown that this is attributable to a combination of wavelength-dependent absorption and scattering by the silks rather than differences in reflectance for the different silks. Phonognatha graeffei dragline silk emerges as a very interesting spider silk with a flat ‘reflectance'/scattering spectrum which may indicate it is a low UV absorbing dielectric micro-fibre. Overall the measurement emerges as having the potential to compare the large numbers of silks from different species to prospect for those which have desirable optical properties.

scholarly journals Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy

Nanophotonics ◽  
2017 ◽  
Vol 6 (1) ◽  
pp. 341-348 ◽  
Author(s):  
Douglas J. Little ◽  
Deb M. Kane
Keyword(s):  
Refractive Index ◽  
Electromagnetic Scattering ◽  
Spider Silk ◽  
Transverse Optical ◽  
Graded Index ◽  
Argiope Keyserlingi ◽  
Wavelength Scale ◽  
Index Contrast ◽  
Spider Silks ◽  
Optical Structure

AbstractThe transverse optical structure of two orb-weaver (family Araneidae) spider dragline silks was investigated using a variant of the inverse-scattering technique. Immersing the silks in a closely refractive index-matched liquid, the minimum achievable image contrast was greater than expected for an optically homogeneous silk, given what is currently known about the optical absorption of these silks. This “excess contrast” indicated the presence of transverse optical structure within the spider silk. Applying electromagnetic scattering theory to a transparent double cylinder, the minimum achievable irradiance contrast for the Plebs eburnus and Argiope keyserlingi dragline silks was determined to be consistent with step index refractive index contrasts of 1−4×10−4 and 6–7×10−4, respectively, supposing outer-layer thicknesses consistent with previous TEM studies (50 nm and 100 nm, respectively). The possibility of graded index refractive index contrasts within the spider silks is also discussed. This is the strongest evidence, to date, that there is a refractive index contrast associated with the layered morphology of spider silks and/or variation of proportion of nanocrystalline components within the spider silk structure. The method is more generally applicable to optical micro-fibers, including those with refractive index variations on a sub-wavelength scale.

Description of Test Setup and Approach to Measure Thermal Properties of Natural and Synthetic Spider Silks at Cryogenic Temperatures

2013 ◽  
Author(s):  
Troy Munro ◽  
Changhu Xing ◽  
Andrew Marquette ◽  
Heng Ban ◽  
Cameron Copeland ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Conformational Changes ◽  
Spider Silk ◽  
Protein Structures ◽  
Cryogenic Temperatures ◽  
Nephila Clavipes ◽  
Silk Fibers ◽  
Spider Silks ◽  
Better Than ◽  
Natural And Synthetic

Spider silk is well-known for its exceptional mechanical properties, such as strength, elasticity and flexibility. Recently, it has been reported that dragline silk from a Nephila clavipes also has an exceptionally high thermal conductivity, comparable to copper when the fiber is stretched. Synthetic spider silks have been spun from spider silk proteins produced in transgenic sources, and their production process has the optimization potential to have properties similar to or better than the natural spider silk. There is interest to measure the thermal properties of natural and synthetic silk at cryogenic temperatures for use of spider silk fibers as heat conduits in systems where component weight is an issue, such as in spacecraft. This low temperature measurement is also of particular interest because of the conformational changes in protein structures, which affect material properties, that occurs at lower temperatures for some proteins. A measurement system has been designed and is being tested to characterize the thermal properties of natural and synthetic spider silks by means of a transient electrothermal method.

Nephila Clavipes Dragline Silk: Approaches to a Recombinantly Produced Silk Protein

1993 ◽  
Vol 330 ◽  
Author(s):  
Charlene M. Mello ◽  
Steven Arcidiacono ◽  
Richard Beckwitt ◽  
John Prince ◽  
Kris Senecal ◽  
...  
Keyword(s):  
High Performance ◽  
Spider Silk ◽  
Recombinant Dna ◽  
Electromagnetic Spectrum ◽  
Nephila Clavipes ◽  
Natural Function ◽  
High Performance Fiber ◽  
Recombinant Dna Techniques ◽  
Clone And Express ◽  
Spider Silks

Spider silks exhibit an unusual combination of strength and toughness that distinguishes them from other natural and synthetic fibers. Silk proteins perform a key natural function as structural fibers, to absorb impact energy from flying insects without breaking. They dissipate energy over a broad area and balance stiffness, strength and extensibility (1,2). In addition to their unusual mechanical properties and visual lustre, silks also exhibit interesting interference patterns within the electromagnetic spectrum (3), unusual viscometric patterns related to processing (4), and piezoelectric properties (3,5,6). These properties suggest they would be good candidates for high performance fiber and composite applications. However, the spider is not capable of producing sufficient quantities of proteins to enable thorough evaluation of their potential. Consequently, we are pursuing recombinant DNA techniques to clone and express adequate quantities of recombinant spider silk for these studies.

Structural/Property Relationships for Optical Materials

1993 ◽  
Vol 329 ◽  
Author(s):  
Vivien D.
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Composition ◽  
Field Strength ◽  
Optical Materials ◽  
Site Occupancy ◽  
Laser Materials ◽  
Crystal Field Strength ◽  
The Matrix

AbstractIn this paper the relationships between the crystal structure, chemical composition and electronic structure of laser materials, and their optical properties are discussed. A brief description is given of the different laser activators and of the influence of the matrix on laser characteristics in terms of crystal field strength, symmetry, covalency and phonon frequencies. The last part of the paper lays emphasis on the means to optimize the matrix-activator properties such as control of the oxidation state and site occupancy of the activator and influence of its concentration.

scholarly journals Nephila clavipes Flagelliform Silk-Like GGX Motifs Contribute to Extensibility and Spacer Motifs Contribute to Strength in Synthetic Spider Silk Fibers

2013 ◽  
Vol 14 (6) ◽  
pp. 1751-1760 ◽  
Author(s):  
Sherry L. Adrianos ◽  
Florence Teulé ◽  
Michael B. Hinman ◽  
Justin A. Jones ◽  
Warner S. Weber ◽  
...  
Keyword(s):  
Spider Silk ◽  
Nephila Clavipes ◽  
Silk Fibers

The mechanical design of spider silks: from fibroin sequence to mechanical function

1999 ◽  
Vol 202 (23) ◽  
pp. 3295-3303 ◽  
Author(s):  
J.M. Gosline ◽  
P.A. Guerette ◽  
C.S. Ortlepp ◽  
K.N. Savage
Keyword(s):  
Mechanical Design ◽  
Polymer Network ◽  
Nephila Clavipes ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Clear Link ◽  
Silk Fibroins ◽  
Araneus Diadematus ◽  
Spider Silks ◽  
Β Sheet

Spiders produce a variety of silks, and the cloning of genes for silk fibroins reveals a clear link between protein sequence and structure-property relationships. The fibroins produced in the spider's major ampullate (MA) gland, which forms the dragline and web frame, contain multiple repeats of motifs that include an 8–10 residue long poly-alanine block and a 24–35 residue long glycine-rich block. When fibroins are spun into fibres, the poly-alanine blocks form (β)-sheet crystals that crosslink the fibroins into a polymer network with great stiffness, strength and toughness. As illustrated by a comparison of MA silks from Araneus diadematus and Nephila clavipes, variation in fibroin sequence and properties between spider species provides the opportunity to investigate the design of these remarkable biomaterials.

scholarly journals Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks

2018 ◽  
Vol 115 (45) ◽  
pp. 11507-11512 ◽  
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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