Linking naturally and unnaturally spun silks through the forced reeling of Bombyx mori.

The forced reeling of silkworms offers the potential to produce a spectrum of silk filaments, spun from natural silk dope and subjected to carefully controlled applied processing conditions. Here we demonstrate that the envelope of stress-strain properties for forced reeled silks can encompass both naturally spun cocoon silk and unnaturally processed artificial silk filaments. We use dynamic mechanical thermal analysis (DMTA) to quantify the structural properties of these silks. Using this well-established mechanical spectroscopic technique, we show high variation in the mechanical properties and the associated degree of disordered hydrogen-bonded structures in forced reeled silks. Furthermore, we show that this disorder can be manipulated by a range of processing conditions and even ameliorated under certain parameters, such as annealing under heat and mechanical load. We conclude that the powerful combination of forced reeling silk and DMTA has tied together native/natural and synthetic/unnatural extrusion spinning. The presented techniques therefore have the ability to define the potential of Bombyx-derived proteins for use in fibre-based applications and serve as a roadmap to improve fibre quality via post-processing.

[1]  David L. Kaplan,et al.  Dynamic Protein−Water Relationships during β-Sheet Formation , 2008 .

[2]  C. Holland,et al.  Forced reeling of Bombyx mori silk: separating behavior and processing conditions. , 2013, Biomacromolecules.

[3]  M. Elices,et al.  Effect of degumming on the tensile properties of silkworm (Bombyx mori) silk fiber , 2002 .

[4]  Markus J Buehler,et al.  Effect of sodium chloride on the structure and stability of spider silk's N-terminal protein domain. , 2013, Biomaterials science.

[5]  D. Porter,et al.  Spider silk as a model biomaterial , 2006 .

[6]  Y. Saegusa,et al.  Physical properties and structure of silk. XI. Glass transition temperature of wild silk fibroins , 1986 .

[7]  Y. Tanabe,et al.  Structure of oriented polystyrene monofilaments and its relationship to brittle-to-ductile transition , 1978 .

[8]  M. Elices,et al.  Tensile properties of silkworm silk obtained by forced silking , 2001 .

[9]  Z. Shao,et al.  Extended wet-spinning can modify spider silk properties. , 2005, Chemical communications.

[10]  Z. Shao,et al.  Investigation of rheological properties and conformation of silk fibroin in the solution of AmimCl. , 2012, Biomacromolecules.

[11]  Yi Liu,et al.  Relationships between supercontraction and mechanical properties of spider silk , 2005, Nature materials.

[12]  C. Viney,et al.  Sample selection, preparation methods, and the apparent tensile properties of silkworm (B. mori) cocoon silk , 2012, Biopolymers.

[13]  Shigeo Nakamura,et al.  Physical properties and structure of silk. III. The glass transition and conformational changes of tussah silk fibroin , 1977 .

[14]  Z. Shao,et al.  Effect of metallic ions on silk formation in the Mulberry silkworm, Bombyx mori. , 2005, The journal of physical chemistry. B.

[15]  David L Kaplan,et al.  Silk-based biomaterials. , 2003, Biomaterials.

[16]  D. Porter,et al.  Silks cope with stress by tuning their mechanical properties under load , 2012 .

[17]  D. Porter,et al.  Two mechanisms for supercontraction in Nephila spider dragline silk. , 2011, Biomacromolecules.

[18]  P. Zhou,et al.  Toughness of Spider Silk at High and Low Temperatures , 2005 .

[19]  Fujia Chen,et al.  Structure and physical properties of silkworm cocoons , 2012, Journal of The Royal Society Interface.

[20]  Z. Shao,et al.  Using solvents with different molecular sizes to investigate the structure of Antheraea pernyi silk. , 2013, Biomacromolecules.

[21]  D. Porter.  Group Interaction Modelling of Polymer Properties , 1995 .

[22]  T. Asakura,et al.  Elucidating Silk Structure Using Solid‐State NMR , 2014 .

[23]  A. Ajji,et al.  Biaxial orientation behavior of polystyrene: Orientation and properties , 2003 .

[24]  Z. Shao,et al.  Wet-spinning of regenerated silk fiber from aqueous silk fibroin solution: discussion of spinning parameters. , 2010, Biomacromolecules.

[25]  Fritz Vollrath,et al.  Thermally induced changes in dynamic mechanical properties of native silks. , 2013, Biomacromolecules.

[26]  Y. Tanabe,et al.  Brittle-to-ductile transition based upon amorphous orientation of polystyrene monofilaments , 1978 .

[27]  Z. Shao,et al.  Enhancing the toughness of regenerated silk fibroin film through uniaxial extension. , 2010, Biomacromolecules.

[28]  Chris Holland,et al.  Natural and unnatural silks , 2007 .

[29]  Hu Tao,et al.  Silk Materials – A Road to Sustainable High Technology , 2012, Advanced materials.

[30]  Fritz Vollrath,et al.  Spider silk as archetypal protein elastomer. , 2006, Soft matter.

[31]  David L. Kaplan,et al.  Role of pH and charge on silk protein assembly in insects and spiders , 2006 .

[32]  Z. Shao,et al.  Silk Fibers Extruded Artificially from Aqueous Solutions of Regenerated Bombyx mori Silk Fibroin are Tougher than their Natural Counterparts , 2009 .

[33]  J. Magoshi,et al.  Physical properties and structure of silk. II. Dynamic mechanical and dielectric properties of silk fibroin , 1975 .

[34]  Thomas Hesselberg,et al.  The impact behaviour of silk cocoons , 2013, Journal of Experimental Biology.

[35]  F. Vollrath,et al.  Beta-silks: enhancing and controlling aggregation. , 2006, Advances in protein chemistry.

[36]  G. Freddi,et al.  Structure and molecular conformation of tussah silk fibroin films treated with water-methanol solutions : Dynamic mechanical and thermomechanical behavior , 1998 .

[37]  Jinrong Yao,et al.  Kinetics of thermally-induced conformational transitions in soybean protein films , 2010 .

[38]  W. Park,et al.  Time-resolved structural investigation of regenerated silk fibroin nanofibers treated with solvent vapor. , 2006, International journal of biological macromolecules.

[39]  Shigeo Nakamura,et al.  Studies on physical properties and structure of silk. Glass transition and crystallization of silk fibroin , 1975 .

[40]  Z. Shao,et al.  Concentration state dependence of the rheological and structural properties of reconstituted silk. , 2009, Biomacromolecules.

[41]  S. Hudson,et al.  Structural characteristics and properties of the regenerated silk fibroin prepared from formic acid. , 2001, International journal of biological macromolecules.

[42]  I. Um,et al.  Thermal behavior of regenerated Antheraea pernyi silk fibroin film treated with aqueous methanol , 2000 .

[43]  F Vollrath,et al.  X-ray diffraction on spider silk during controlled extrusion under a synchrotron radiation X-ray beam. , 2000, Biomacromolecules.

[44]  Graham Williams,et al.  Anelastic and Dielectric Effects in Polymeric Solids , 1991 .

[45]  Michael G. Sehorn,et al.  Spidroin N-terminal Domain Promotes a pH-dependent Association of Silk Proteins during Self-assembly* , 2010, The Journal of Biological Chemistry.

[46]  Z. Shao,et al.  Copper in the silk formation process of Bombyx mori silkworm , 2003, FEBS letters.

[47]  David L. Kaplan,et al.  Determining Beta-Sheet Crystallinity in Fibrous Proteins by Thermal Analysis and Infrared Spectroscopy , 2006 .

[48]  Fritz Vollrath,et al.  Materials: Surprising strength of silkworm silk , 2002, Nature.

[49]  Mikihiko Miura,et al.  Structural characteristics and properties of Bombyx mori silk fiber obtained by different artificial forcibly silking speeds. , 2008, International journal of biological macromolecules.

[50]  C. Craig,et al.  Evolution of arthropod silks. , 1997, Annual review of entomology.

[51]  James L White,et al.  Structure development in biaxially stretched polystyrene film: Part I. Property-orientation correlation , 1989 .

[52]  Fritz Vollrath,et al.  Silk as a Biomimetic Ideal for Structural Polymers , 2009 .

[53]  Fritz Vollrath,et al.  There are many more lessons still to be learned from spider silks , 2011 .

[54]  Jinrong Yao,et al.  Correlation between structural and dynamic mechanical transitions of regenerated silk fibroin , 2010 .

[55]  I. Ward,et al.  The crystal modulus and structure of oriented poly(ethylene terephthalate) , 1988 .

[56]  Ray Gunawidjaja,et al.  Mechanical Properties of Robust Ultrathin Silk Fibroin Films , 2007 .

[57]  David L. Kaplan,et al.  Mechanism of silk processing in insects and spiders , 2003, Nature.

[58]  C. Migliaresi,et al.  Regenerated silk fibroin films: Thermal and dynamic mechanical analysis , 2002 .

[59]  D. Kaplan,et al.  Silk self-assembly mechanisms and control from thermodynamics to kinetics. , 2012, Biomacromolecules.

[60]  T. Asakura,et al.  Some observations on the structure and function of the spinning apparatus in the silkworm Bombyx mori. , 2007, Biomacromolecules.

[61]  Z. Shao,et al.  Further investigation on potassium-induced conformation transition of Nephila spidroin film with two-dimensional infrared correlation spectroscopy. , 2005, Biomacromolecules.

[62]  Fritz Vollrath,et al.  Spider silk protein refolding is controlled by changing pH. , 2004, Biomacromolecules.

[63]  M. Knight,et al.  Beta transition and stress-induced phase separation in the spinning of spider dragline silk. , 2000, International journal of biological macromolecules.

[64]  Fritz Vollrath,et al.  Small angle neutron scattering of native and reconstituted silk fibroin , 2010 .

[65]  C. Siviour,et al.  In situ tensile tests of single silk fibres in an environmental scanning electron microscope (ESEM) , 2013, Journal of Materials Science.

[66]  D. Porter,et al.  Predictive nonlinear constitutive relations in polymers through loss history , 2009 .

[67]  K. Ohgo,et al.  Preparation and characterization of regenerated Bombyx mori silk fibroin fiber with high strength , 2008 .