Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Progress in Materials Science

Volumn 76, Issue , 2016, Pages 229-318

  Wang, Bin ^a   Yang, Wen ^a   McKittrick, Joanna ^a   Meyers, Marc André ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

Biochemistry; Bioinspiration; Filament matrix structure; Keratins and keratinous materials; Mechanical property

Indexed keywords

EID: 84944936702     PISSN: 00796425     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.pmatsci.2015.06.001     Document Type: Review

References (317)

1. M. Sarikaya An introduction to biomimetics: a structural viewpoint Microsc Res Tech 27 5 1994 360 375
2. A.V. Srinivasan, G.K. Haritos, and F.L. Hedberg Biomimetics: advancing man-made materials through guidance from nature Appl Mech Rev 44 11 1991 463
3. G. Mayer, and M. Sarikaya Rigid biological composite materials: structural examples for biomimetic design Exp Mech 42 4 2002 395 403
4. E. Baer, A. Hiltner, and R.J. Morgan Biological and synthetic hierarchical composites Phys Today 45 10 1992 60
5. M.A. Meyers, P.-Y. Chen, A.Y.-M. Lin, and Y. Seki Biological materials: structure and mechanical properties Prog Mater Sci 53 1 2008 1 206
6. M.A. Meyers, J. McKittrick, and P.-Y. Chen Structural biological materials: critical mechanics-materials connections Science 339 6121 2013 773 779
7. J.F.V. Vincent Structural biomaterials revised ed. 1990 Princeton University Press
8. M.A. Meyers, and P.-Y. Chen Biological materials science 2014 Cambridge University Press Cambridge, UK
9. A. Miserez, C. Weaver, and O. Chaudhuri Biological materials and molecular biomimetics - filling up the empty soft materials space for tissue engineering applications J Mater Chem B: Mater Biol Med 3 1 2015 13 24
10. M.F. Ashby, L.J. Gibson, U. Wegst, and R. Olive The mechanical properties of natural materials. I. Material property charts Proc R Soc A: Math Phys Eng Sci 450 1938 1995 123 140
11. P.A. Coulombe, and M.B. Omary 'Hard' and 'soft' principles defining the structure, function and regulation of keratin intermediate filaments Curr Opin Cell Biol 14 1 2002 110 122
12. J. McKittrick, P.Y. Chen, S.G. Bodde, W. Yang, E.E. Novitskaya, and M.A. Meyers The structure, functions, and mechanical properties of keratin JOM 64 4 2012 449 468
13. U.G.K. Wegst, and M.F. Ashby The mechanical efficiency of natural materials Philos Mag 84 21 2004 2167 2186
14. L.J. Szewciw, D.G. de Kerckhove, G.W. Grime, and D.S. Fudge Calcification provides mechanical reinforcement to whale baleen alpha-keratin Proc Biol Sci 277 1694 2010 2597 2605
15. E.H. Mercer Keratin and keratinization: an essay in molecular biology 1961 Pergamon
16. R.D.B. Fraser, T.P. MacRae, and G.E. Rogers Keratins: their composition, structure and biosynthesis 1972 Charles C Thomas
17. M. Feughelman Mechanical properties and structure of alpha-keratin fibers: wool, human hair and related fibers 1997 University of New South Wales Press
18. A. Miserez, and P.A. Guerette Phase transition-induced elasticity of α-helical bioelastomeric fibres and networks Chem Soc Rev 42 5 2013 1973 1995
19. H. Herrmann, and U. Aebi Intermediate filaments: molecular structure, assembly mechanism, and integration into functionally distinct intracellular scaffolds Annu Rev Biochem 73 2004 749 789
20. J. Schweizer, P.E. Bowden, P.A. Coulombe, L. Langbein, E.B. Lane, T.M. Magin, and et al. New consensus nomenclature for mammalian keratins J Cell Biol 174 2 2006 169 174
21. R.I.C. Spearman On the nature of the horny scales of the pangolin J Linn Soc Zool 46 310 1967 267 273
22. W.T. Astbury, and A. Street X-ray studies of the structure of hair, wool, and related fibres. I. General Philos Trans R Soc Lond A 230 681-693 1932 75 101
23. W.T. Astbury, and H.J. Woods X ray studies of the structure of hair, wool, and related fibres. II. The molecular structure and elastic properties of hair keratin Philos Trans R Soc Lond B 114 788 1934 314 316
24. R.D.B. Fraser, T.P. MacRae, D.A.D. Parry, and E. Suzuki The structure of beta-keratin Polymer 10 1969 810 826
25. R.D.B. Fraser, and T.P. MacRae The structure of α-keratin Structure 14 September 1973 61 67
26. R.D.B. Fraser, and D.A.D. Parry The structural basis of the filament-matrix texture in the avian/reptilian group of hard β-keratins J Struct Biol 173 2 2011 391 405
27. Parry DAD. Personal communications; 2014.
28. H. Lodish, A. Berk, S.L. Zipursky, P. Matsudaira, D. Baltimore, and J. Darnell Molecular cell biology 4th ed. 2000 W.H. Freeman and Company New York
29. R.S. Bear, and H.J. Rugo The results of X-ray diffraction studies on keratin fibers Ann N Y Acad Sci 53 3 1951 627 648
30. B. Busson, F. Briki, and J. Doucet Side-chains configurations in coiled coils revealed by the 5.15 - a meridional reflection on hard alpha-keratin X-ray diffraction patterns J Struct Biol 125 1 1999 1 10
31. P.Y. Chen, J. McKittrick, and M.A. Meyers Biological materials: functional adaptations and bioinspired designs Prog Mater Sci 57 8 2012 1492 1704
32. A. Giroud, and C.P. Leblond The keratinization of epidermis and its derivatives, especially the hair, as shown by X-ray diffraction and histochemical studies Ann N Y Acad Sci 53 3 1951 613 626
33. L. Alibardi, L. Dalla Valle, A. Nardi, and M. Toni Evolution of hard proteins in the sauropsid integument in relation to the cornification of skin derivatives in amniotes J Anat 214 4 2009 560 586
34. Strasser B, Mlitz V, Hermann M, Rice RH, Richard A. Evolutionary origin and diversification of epidermal barrier proteins in amniotes; 2014.
35. J. Squire, P.J. Vibert, and A. Elliott Fibrous protein structure 1987 Academic Press San Diego, US
36. J.M. Gillespie The proteins of hair and other hard α-keratins R.D. Goldman, P.M. Steinert, Cellular and molecular biology of intermediate filaments 1990 Springer US 95 128
37. L. Alibardi, L. Dalla Valle, V. Toffolo, and M. Toni Scale keratin in lizard epidermis reveals amino acid regions homologous with avian and mammalian epidermal proteins Anat Rec - Part A Discov Mol Cell Evol Biol 288 7 2006 734 752
38. L.N. Jones, M. Simon, N.R. Watts, F.P. Booy, A.C. Steven, and D.A.D. Parry Intermediate filament structure: hard α-keratin Biophys Chem 68 1-3 1997 83 93
39. D.A.D. Parry Hard α-keratin intermediate filaments: an alternative interpretation of the low-angle equatorial X-ray diffraction pattern, and the axial disposition of putative disulphide bonds in the intra- and inter-protofilamentous networks Int J Biol Macromol 19 1 1996 45 50
40. D.L. Nelson, and M.M. Cox Lehninger principles of biochemistry 5th ed. 2008 W.H. Freeman and Company New York
41. F.H.C. Crick Is α-keratin a coiled coil? Nat Publ Gr 170 1952 882 883
42. F.H.C. Crick The packing of α-helices: simple coiled-coils Acta Crystallogr 6 1953 689 697
43. L. Pauling, R.B. Corey, and H.R. Branson The structure of proteins; two hydrogen-bonded helical configurations of the polypeptide chain Proc Natl Acad Sci USA 37 4 1951 205 211
44. J. McMurry, and R. Fay Biochemistry Chemistry 4th ed. 2003 Pearson Prentice Hall
45. D. Voet, J.G. Voet, and C.W. Pratt Biochemistry: life at the molecular level 3rd ed. 2008 John Wiley & Sons New York
46. C.-C. Chou, and M.J. Buehler Structure and mechanical properties of human trichocyte keratin intermediate filament protein Biomacromolecules 13 11 2012 3522 3532
47. R.D.B. Fraser, T.P. MacRae, L.G. Sparrow, and D.A.D. Parry Disulphide bonding in α-keratin Int J Biol Macromol 10 2 1988 106 112
48. C.-H. Lee, M.-S. Kim, B.M. Chung, D.J. Leahy, and P.A. Coulombe Structural basis for heteromeric assembly and perinuclear organization of keratin filaments Nat Struct Mol Biol 19 7 2012 707 715
49. S.V. Strelkov, H. Herrmann, N. Geisler, T. Wedig, R. Zimbelmann, U. Aebi, and et al. Conserved segments 1A and 2B of the intermediate filament dimer: their atomic structures and role in filament assembly EMBO J 21 6 2002 1255 1266
50. A.A. Chernyatina, S. Nicolet, U. Aebi, H. Herrmann, and S.V. Strelkov Atomic structure of the vimentin central-helical domain and its implications for intermediate filament assembly Proc Natl Acad Sci 109 34 2012 13620 13625
51. R. Moll, W.W. Franke, and D.L. Schiller The catalog of human cytokeratins: patterns of expression in normal epithelia, tumors and cultured cells Cell 31 November 1982 11 24
52. S.C. Tseng, M.J. Jarvinen, W.G. Nelson, J.W. Huang, J. Woodcock-Mitchell, and T.T. Sun Correlation of specific keratins with different types of epithelial differentiation: monoclonal antibody studies Cell 30 2 1982 361 372
53. Y.J. Wu, L.M. Parker, N.E. Binder, M.A. Beckett, J.H. Sinard, C.T. Griffiths, and et al. The mesothelial keratins: a new family of cytoskeletal proteins identified in cultured mesothelial cells and nonkeratinizing epithelia Cell 31 3 Pt 2 1982 693 703
54. R. Moll, M. Divo, and L. Langbein The human keratins: biology and pathology Histochem Cell Biol 129 6 2008 705 733
55. L.M. Dowling, W.G. Crewther, and D.A.D. Parry Secondary structure of component 8c-1 of alpha-keratin. An analysis of the amino acid sequence Biochem J 236 3 1986 705 712
56. R.D.B. Fraser, T.P. MacRae, D.A.D. Parry, and E. Suzuki Intermediate filaments in α-keratins Proc Natl Acad Sci USA 83 5 1986 1179 1183
57. R.D.B. Fraser, and D.A.D. Parry Molecular packing in the feather keratin filament J Struct Biol 162 1 2008 1 13
58. D.M. Lewis, and J.A. Rippon The coloration of wool and other keratin fibres 2013 John Wiley
59. P.M. Steinert, R.H. Rice, D.R. Roop, B.L. Trus, and A.C. Steven Complete amino acid sequence of a mouse epidermal keratin subunit and implications for the structure of intermediate filaments Nature 302 5911 1983 794 800
60. P.M. Steinert, and D.A.D. Parry Intermediate filaments: conformity and diversity of expression and structure Annu Rev Cell Biol 1 1985 41 65
61. W.G. Crewther, and L.M. Dowling 55-Effects of chemical modifications on the physical properties of wool: a model of the wool fiber J Text Inst Trans 51 12 1960 T775 T791
62. H.W. Harding, and G.E. Rogers ε-(γ-Glutamyl)lysine cross-linkage in citrulline-containing protein fractions from hair Biochemistry 10 4 1971 624 630
63. B. Milligan, L.A. Holt, and J.B. Caldwell The enzymic hydrolysis of wool for amino acid analysis Appl Poly Symp 18 1971 113 125
64. I.J. O'Donnell, and E.O.P. Thompson Studies on oxidized wool VI. Interactions between high and low-sulfur proteins and their significance in the purification of extracted wool proteins Aust J Biol Sci 15 1962 740 756
65. I.J. O'Donnell, and E.O.P. Thompson Studies on reduced wool IV. The isolation of a major component Aust J Biol Sci 17 1964 973 978
66. P. Alexander, and C. Earland Structure of wool fibers. Isolation of an α- and β-protein in wool Nature 166 1950 396 397
67. J.M. Swan Thiols, disulphides and thiosulphates: some new reactions and possibilities in peptide and protein chemistry Nature 180 1957 643 645
68. D.R. Goddard, and L. Michaelis A study on keratin J Biol Chem 106 2 1934 605 614
69. B.S. Harrap, and E.F. Woods Soluble derivatives of feather keratin. 1. Isolation, fractionation and amino acid composition Biochem J 92 1 1964 8 18
70. A. Gennadios Protein-based films and coatings 2002 CRC Press
71. B.L.A. Holt, B. Milligan, and C.M. Roxburgh Aspartic acid, asparagine, glutamic acid, and glutamine contents of wool and two derived protein fractions Aust J Biol Sci 24 3 1971 509 514
72. E.O.P. Thompson, and I.J. O'Donnell Studies on reduced wool I. The extent of reduction of wool with increasing concentrations of thiol, and the extraction of proteins from reduced and alkylated wool Aust J Biol Sci 15 1962 757
73. B.S. Harrap, and E.F. Woods Soluble derivatives of feather keratin. 2. Molecular weight and conformation Biochem J 92 1 1964 19 26
74. P.A. Gerber, B.A. Buhren, H. Schrumpf, B. Homey, A. Zlotnik, and P. Hevezi The top skin-associated genes: a comparative analysis of human and mouse skin transcriptomes Biol Chem 395 6 2014 577 591
75. M.J. Greenwold, and R.H. Sawyer Molecular evolution and expression of archosaurian β-keratins: diversification and expansion of archosaurian β-keratins and the origin of feather β-keratins J Exp Zool Part B: Mol Dev Evol 320 6 2013 393 405
76. H. Padykula Control mechanisms in the expression of cellular phenotypes. In: Symposia of the international society for cell biology vol. 9 1970 Academic Press New York and London
77. G.E. Rogers The structure and biochemistry of keratin E.E. Bittar, N. Bittar, The biological basis of medicine 1969 Academic Press New York 21 57
78. R.C. Marshall, D.F. Orwin, and J.M. Gillespie Structure and biochemistry of mammalian hard keratin Electron Microsc Rev 4 1 1991 47 83
79. D.J. Kemp, P.Y. Dyer, and G.E. Rogers Keratin synthesis during development of the embryonic chick feather J Cell Biol 62 1 1974 114 131
80. K. Gregg, and G.E. Rogers Feather keratin: composition, structure and biogenesis J. Bereiter-Hahn, A.G. Matoltsy, K.S. Richards, Biology of the integument 1986 Springer Berlin, Heidelberg 666 694
81. D.J. Tomlinson, C.H. Mülling, and T.M. Fakler Invited review: formation of keratins in the bovine claw: roles of hormones, minerals, and vitamins in functional claw integrity J Dairy Sci 87 4 2004 797 809
82. C.K.W. Mülling Three-dimensional appearance of bovine epidermal keratinocytes in different stages of differentiation revealed by cell maceration and scanning electron microscopic investigation Folia Morphol (Warsz) 59 4 2000 239 246
83. Mülling C, Lischer CJ. New aspects of etiology and pathogenesis of laminitis in cattle. In: Recent advances in bovine medicine. World buriatrics conf; 2002. p. 2-13.
84. I. Brody The ultrastructure of the tonofibrils in the keratinization process of normal human epidermis J Ultrastruct Res 4 3-4 1960 264 297
85. S. Roth, and W.H. Clark Ultrastructural evidence related to the mechanism of keratin synthesis W. Montagna, W.C. Lobitz, The epidermis 1964 Academic Press Inc. New York 303
86. A.G. Matoltsy, and T. Huszar Keratinization of the reptilian epidermis: an ultrastructural study of the turtle skin J Ultrastruct Res 38 1 1972 87 101
87. A.G. Matoltsy Keratinization of the avian epidermis: an ultrastructural study of the newborn chick skin J Ultrastruct Res 29 5-6 1969 438 458
88. P.F.A. Maderson, W.J. Hillenius, U. Hiller, and C.C. Dove Towards a comprehensive model of feather regeneration J Morphol 270 10 2009 1166 1208
89. L. Alibardi, and M. Toni Cytochemical and molecular characteristics of the process of cornification during feather morphogenesis Prog Histochem Cytochem 43 1 2008 1 69
90. L. Alibardi Ultrastructure of the feather follicle in relation to the formation of the rachis in pennaceous feathers Anat Sci Int 85 2 2010 79 91
91. B.K. Filshie, and G.E. Gogers An electron microscope study of the fine structure of feather keratin J Cell Biol 13 1 1962 1 12
92. H.P. Baden, and P.F. Maderson Morphological and biophysical identification of fibrous proteins in the amniote epidermis J Exp Zool 174 2 1970 225 232
93. L. Alibardi Immunolocalization of alpha-keratins and feather beta-proteins in feather cells and comparison with the general process of cornification in the skin of mammals Ann Anat 195 2 2013 189 198
94. D.H. Matulionis Morphology of the developing down feathers of chick embryos. A descriptive study at the ultrastructural level of differentiation and keratinization Z Anat Entw Gesch 132 2 1970 107 157
95. L. Alibardi Keratinization and lipogenesis in epidermal derivatives of the zebrafinch, Taeniopygia guttata castanotis (Aves, Passeriformes, ploecidae) during embryonic development J Morphol 251 3 2002 294 308
96. E. Schmid, S. Tapscott, G.S. Bennett, J. Croop, S.a. Fellini, H. Holtzer, and et al. Differential location of different types of intermediate-sized filaments in various tissues of the chicken embryo Differentiation 15 1 1979 27 40
97. W. Meyer, and G. Baumgärtner Embryonal feather growth in the chicken J Anat 193 Pt 4 1998 611 616
98. L. Alibardi, and M.B. Thompson Epidermal differentiation during carapace and plastron formation in the embryonic turtle Emydura macquarii J Anat 194 Pt 4 1999 531 545
99. L. Alibardi Immunocytochemical observations on the cornification of soft and hard epidermis in the turtle Chrysemys picta Zoology (Jena) 105 1 2002 31 44
100. R.D.B. Fraser, and D.A.D. Parry The molecular structure of reptilian keratin Int J Biol Macromol 19 3 1996 207 211
101. E.G. Bendit The α-β transformation in keratin Nature 179 1957 535
102. J. Cao Is the α-β transition of keratin a transition of α-helices to β-pleated sheets. II. Synchrotron investigation for stretched single specimens J Mol Struct 607 1 2002 69 75
103. L. Kreplak, J. Doucet, P. Dumas, and F. Briki New aspects of the α-helix to β-sheet transition in stretched hard α-keratin fibers Biophys J 87 1 2004 640 647
104. F.G.E. Pautard Mineralization of keratin and its comparison with the enamel matrix Nature 199 1963 9531 9535
105. M. Feughelman A two-phase structure for keratin fibers Text Res J 29 3 1959 223 228
106. M. Feughelman A model for the mechanical properties of the α-keratin cortex Text Res J 64 4 1994 236 239
107. F.-J. Wortmann, and H. Zahn The stress/strain curve of α-keratin fibers and the structure of the intermediate filament Text Res J 64 12 1994 737 743
108. B.M. Chapman A review of mechanical properties of keratin fibres J Text Inst 60 5 1969 181 207
109. J.W.S. Hearle A critical review of the structural mechanics of wool and hair fibres Int J Biol Macromol 27 2 2000 123 138
110. B.M. Chapman A mechanical model for wool and other keratin fibers Text Res J 39 12 1969 1102 1109
111. R.D.B. Fraser, and T.P. MacRae Molecular structure and mechanical properties of keratins J.F.V. Vincent, J.D. Currey, The mechanical properties of biological materials (proceedings of the symposia of the society for experimental biology) 1980 Cambridge University Press Cambridge, UK 211 246
112. D.S. Fudge, K.H. Gardner, V.T. Forsyth, C. Riekel, and J.M. Gosline The mechanical properties of hydrated intermediate filaments: insights from hagfish slime threads Biophys J 85 3 2003 2015 2027
113. L. Kreplak, J. Doucet, and F. Briki Unraveling double stranded α-helical coiled coils: an X-ray diffraction study on hard α-keratin fibers Biopolymers 58 5 2001 526 533
114. M.A. Kasapi, and J.M. Gosline Micromechanics of the equine hoof wall: optimizing crack control and material stiffness through modulation of the properties of keratin J Exp Biol 202 Pt 4 1999 377 391
115. D.S. Fudge, and J.M. Gosline Molecular design of the alpha-keratin composite: insights from a matrix-free model, hagfish slime threads Proc Biol Sci 271 1536 2004 291 299
116. A. Miserez, S.S. Wasko, C.F. Carpenter, and J.H. Waite Non-entropic and reversible long-range deformation of an encapsulating bioelastomer Nat Mater 8 11 2009 910 916
117. M.A. Kasapi, and J.M. Gosline Strain-rate-dependent mechanical properties of the equine hoof wall J Exp Biol 199 Pt 5 1996 1133 1146
118. J.E. Gubernatis, E. Domany, J.A. Krumhansl, and M. Huberman The Born approximation in the theory of the scattering of elastic waves by flaws J Appl Phys 48 7 1977 2812 2819
119. E. Kjartansson Constant Q-wave propagation and attenuation J Geophys Res 84 B9 1979 4737
120. R.H.C. Bonser, and P.P. Purslow The Young's modulus of feather keratin J Exp Biol 1033 4 1995 1029 1033
121. T.L. Szabo, and J. Wu A model for longitudinal and shear wave propagation in viscoelastic media J Acoust Soc Am 107 5 2000 2437
122. M. Feughelman, and M.S. Robinson The relationship between some mechanical properties of single wool fibers and relative humidity Text Res J 37 6 1967 441 446
123. J.E. Bertram, and J.M. Gosline Functional design of horse hoof keratin: the modulation of mechanical properties through hydration effects J Exp Biol 130 1987 121 136
124. T.M. Winegard, and D.S. Fudge Deployment of hagfish slime thread skeins requires the transmission of mixing forces via mucin strands J Exp Biol 213 Pt 8 2010 1235 1240
125. A. Kitchener, and J.F.V. Vincent Composite theory and the effect of water on the stiffness of horn keratin J Mater Sci 22 4 1987 1385 1389
126. S.Z. Li Ben Cao Gang Mu 2005 The Time Literature & Art Press Changchun, China
127. J.G. Rouse, and M.E. Van Dyke A review of keratin-based biomaterials for biomedical applications Materials (Basel) 3 2 2010 999 1014
128. Hofmeier J. Horn-lime plastic masses from keratin substances. Ger pat no 184915; 1905.
129. H.N. Dale Keratin and other coatings for pills Pharmacol J 129 1932 494 495
130. Beyer C. The keratin or horny substance of the hair. Ger pat no 22643; 1907.
131. Fraser RDB, MacRae TP. Schematic diagram of the wool fibre. Commonwealth Scientific and Industrial Research Organisation. < http://www.csiropedia.csiro.au/display/CSIROpedia/Wool+fibre+structure >.
132. D. Rivett, C. Ward, L. Belkin, J. Ramshaw, and J. Wilshire Keratin and wool research The Lennox legacy: the history of the CSIRO Laboratory at 343 Royal Parade Parkville 1996 CSIRO Publishing Collingwood, VIC, Australia
133. J.M. Gillespie, and M.J. Frenkel The diversity of keratins Comp Biochem Physiol Part B: Comp Biochem 47 2 1974 339 346
134. Y. Kawano, and S. Okamoto Film and gels of keratin Kagaku to Seibutsu 13 5 1975 291 292
135. M. van de Locht Reconstitution of microfibrils from wool and filaments from epidermis proteins Melliand Textilberichte 10 1987 780 786
136. H. Ito, T. Miyamoto, H. Inagaki, and Y. Noishiki Biocompatibility of denatured keratins from wool Kobunshi Ronbunshu 39 4 1982 249 256
137. G. Schwinger, K. Zanger, and H. Greven Structural and mechanical aspects of the skin of Bufo marinus (Anura, Amphibia) Tissue Cell 33 5 2001 541 547
138. J.F.V. Vincent, and P. Owers Mechanical design of hedgehog spines and porcupine quills J Zool 210 1 1986 55 75
139. W. Yang, and J. McKittrick Separating the influence of the cortex and foam on the mechanical properties of porcupine quills Acta Biomater 9 11 2013 9065 9074
140. L. Farren, S. Shayler, and A.R. Ennos The fracture properties and mechanical design of human fingernails J Exp Biol 207 5 2004 735 741
141. A. Kitchener Fracture toughness of horns and a reinterpretation of the horning behaviour of bovids J Zool 213 4 1987 621 639
142. A. Kitchener Effect of water on the linear viscoelasticity of horn sheath keratin J Mater Sci Lett 6 3 1987 321 322
143. R.H.C. Bonser The mechanical performance of meduallary foam from feathers J Mater Sci Lett 20 2001 941 942 no. c
144. S.G. Bodde, M.A. Meyers, and J. McKittrick Correlation of the mechanical and structural properties of cortical rachis keratin of rectrices of the Toco toucan (Ramphastos toco) J Mech Behav Biomed Mater 4 5 2011 723 732
145. J. McKittrick, P.Y. Chen, L. Tombolato, E.E. Novitskaya, M.W. Trim, G.a. Hirata, and et al. Energy absorbent natural materials and bioinspired design strategies: a review Mater Sci Eng C 30 3 2010 331 342
146. G.E. Rogers Electron microscope studies of hair and wool Ann N Y Acad Sci 83 3 1959 378 399
147. G.E. Rogers Electron microscopy of wool J Ultrastruct Res 2 3 1959 309 330
148. W.E. Morton, and J.W. Hearle Physical properties of textile fibres 3rd ed. 1993 The Textile Institute Manchester, UK
149. K.S. Wu, W.W. Van Osdol, and R.H. Dauskardt Mechanical properties of human stratum corneum: effects of temperature, hydration, and chemical treatment Biomaterials 27 5 2006 785 795
150. S.F. Chou, and R.A. Overfelt Tensile deformation and failure of North American porcupine quills Mater Sci Eng C 31 8 2011 1729 1736
151. M.W. Trim, M.F. Horstemeyer, H. Rhee, H. El Kadiri, L.N. Williams, J. Liao, and et al. The effects of water and microstructure on the mechanical properties of bighorn sheep (Ovis canadensis) horn keratin Acta Biomater 7 3 2011 1228 1240
152. A.M. Taylor, R.H.C. Bonser, and J.W. Farrent The influence of hydration on the tensile and compressive properties of avian keratinous tissues J Mater Sci 39 3 2004 939 942
153. Y. Seki, M.S. Schneider, and M.A. Meyers Structure and mechanical behavior of a toucan beak Acta Mater 53 20 2005 5281 5296
154. M.C.G. Klein, J.K. Deuschle, and S.N. Gorb Material properties of the skin of the Kenyan sand boa Gongylophis colubrinus (Squamata, Boidae) J Comp Physiol A: Neuroethol Sensory Neural Behav Physiol 196 9 2010 659 668
155. Wang B, Yang W, Meyers MA. Unpublished results; 2014.
156. P.A. Coulombe, and P. Wong Cytoplasmic intermediate filaments revealed as dynamic and multipurpose scaffolds Nat Cell Biol 6 8 2004 699 706
157. Scanning electron micrograph of stratum corneum. < http://feleciaroselabs.com/wp-content/uploads/2012/05/SC.jpg >.
158. G. Plewig, and R.R. Marples Regional differences of cell sizes in the human stratum corneum. Part I J Invest Dermatol 54 1 1970 13 18
159. P. Ovaere, S. Lippens, P. Vandenabeele, and W. Declercq The emerging roles of serine protease cascades in the epidermis Trends Biochem Sci 34 9 2009 453 463
160. Y.S. Papir, K.H. Hsu, and R.H. Wildnauer The mechanical properties of stratum corneum: I. The effect of water and ambient temperature on the tensile properties of newborn rat stratum corneum Biochim Biophys Acta 399 1975 170 180
161. Y. Yuan, and R. Verma Measuring microelastic properties of stratum corneum Colloids Surf B: Biointerfaces 48 1 2006 6 12
162. K.S. Wu, M.M. Stefik, K.P. Ananthapadmanabhan, and R.H. Dauskardt Graded delamination behavior of human stratum corneum Biomaterials 27 34 2006 5861 5870
163. K. Biniek, K. Levi, and R.H. Dauskardt Solar UV radiation reduces the barrier function of human skin Proc Natl Acad Sci 109 42 2012 17111 17116
164. M. Feughelman, and a.R. Haly The mechanical properties of wool keratin and its molecular configuration Kolloid-Zeitschrift 168 2 1960 107 115
165. J. Fan, and W.D. Yu Fractal analysis of the ortho-cortex and para-cortex of wool fiber Adv Mater Res 197-198 2011 86 89
166. G.E. Rogers, and B.K. Filshie Some aspects of the ultrastructure of a-keratin, bacterial flagella, and feather keratin R. Borasky, Ultrastructure of protein fibres 1963 Academic Press Inc. New York 123 138
167. M.G. Dobb Electron-diffraction studies of keratin cells J Text Inst 61 5 1970 232 234
168. W.G. Crewter The effects of disaggregating agents on the stress-strain relationship for wool fibers Text Res J 42 2 1972 77 85
169. J.W.S. Hearle The structural mechanics of fibers J Polym Sci Part C: Polym Symp 20 1 1967 215 251
170. M. Feughelman Keratin Encyclopaedia of polymer science and engineering 2nd ed., vol. 8 1987 John Wiley and Son Inc. New York 566 600
171. E.G. Bendit A quantitative X-ray diffraction study of the alpha-beta transformation in wool keratin Text Res J 30 8 1960 547 555
172. L.R.G. Treloar The physics of rubber elasticity 1975 Clarendon Press Oxford
173. M.J. Harrington, S.S. Wasko, A. Masic, F.D. Fischer, H.S. Gupta, and P. Fratzl Pseudoelastic behaviour of a natural material is achieved via reversible changes in protein backbone conformation J R Soc Interface 9 76 2012 2911 2922
174. J.L. Woods, D.P. Harland, J.A. Vernon, G.L. Krsinic, and R.J. Walls Morphology and ultrastructure of antler velvet hair and body hair from red deer (Cervus elaphus) J Morphol 272 1 2011 34 49
175. Yu Y, Wang B, Meyers MA. Unpublished results; 2015.
176. G.N. Karam, and L.J. Gibson Biomimicking of animal quills and plant stems: natural cylindrical shells with foam cores Mater Sci Eng C 2 1-2 1994 113 132
177. G.N. Karam, and L.J. Gibson Elastic buckling of cylindrical shells with elastic cores - I. Analysis Int J Solids Struct 32 8-9 1995 1259 1283
178. G.N. Karam, and L.J. Gibson Elastic buckling of cylindrical shells with elastic cores - II. Experiments Int J Solids Struct 32 8-9 1995 1285 1306
179. W. Yang, C. Chao, and J. McKittrick Axial compression of a hollow cylinder filled with foam: a study of porcupine quills Acta Biomater 9 2 2013 5297 5304
180. B. Busson, P. Engström, and J. Doucet Existence of various structural zones in keratinous tissues revealed by X-ray microdiffraction J Synchrotron Radiat 6 5 1999 1021 1030
181. S.F. Chou, R.A. Overfelt, and M.E. Miller Anisotropic mechanical behavior of keratin tissue from quill shells of North American porcupine (Erethizon dorsatum) Mater Sci Eng A 557 2012 36 44
182. S. Timoshenko Theory of elastic stability 1936 McGraw-Hill New York
183. L.J. Gibson, and M.F. Ashby Cellular solids: structures and properties 1988 Pergamon Press New York, Oxford
184. V. Geist The evolution of horn-like organs Behavior 27 1 1955 175 214
185. L. Tombolato, E.E. Novitskaya, P.Y. Chen, F.A. Sheppard, and J. McKittrick Microstructure, elastic properties and deformation mechanisms of horn keratin Acta Biomater 6 2 2010 319 330
186. A.C. Kitchener Fighting and the mechanical design of horns and antlers P. Domenici, R.W. Blake, Biomechanics in animal behaviour 2000 BIOS Scientific Publishers Oxford
187. J.D. Currey Mechanical properties of bone tissues with greatly differing functions J Biomech 12 4 1979 313 319
188. J.E. Gordon Structures or why things don't fall down 1978 Penguin Books London
189. B.W. Li, H.P. Zhao, X.Q. Feng, W.W. Guo, and S.C. Shan Experimental study on the mechanical properties of the horn sheaths from cattle J Exp Biol 213 3 2010 479 486
190. F.L. Warburton Determination of the elastic properties of horn keratin J Text Inst Proc 39 7 1948 297 308
191. A. Kelly Strong solids 1973 Clarendon Press Oxford
192. M. Feughelman, and M.S. Robinson Some mechanical properties of wool fibers in the 'hookean' region from zero to 100% relative humidity Text Res J 41 6 1971 469 474
193. M.A. Kasapi, and J.M. Gosline Design complexity and fracture control in the equine hoof wall J Exp Biol 200 Pt 11 1997 1639 1659
194. R. Nickel Über den Bau der Hufröhrchen und seine Bedeutung für den Mechanismus des Pferdehufes Morph Jb 82 1938 119 160
195. M.L. Ryder Structure of rhinoceros horn Nature 193 1962 1199 1201
196. J.E. Bertram, and J.M. Gosline Fracture toughness design in horse hoof keratin J Exp Biol 125 1986 29 47
197. J. Cook, J.E. Gordon, C.C. Evans, and D.M. Marsh A mechanism for the control of crack propagation in all-brittle systems Proc R Soc Lond A: Math Phys Eng Sci 282 1391 1964 508 520
198. T.M. Wright, and W.C. Hayes Fracture mechanics parameters for compact bone-effects of density and specimen thickness J Biomech 10 7 1977 419 430
199. D.H. Leach The structure and function of equine hoof wall 1980 University of Saskatchewan
200. M.W. Hamrick Functional and adaptive significance of primate pads and claws: evidence from New World anthropoids Am J Phys Anthropol 106 2 1998 113 127
201. R. Caputo, G. Gasparini, and D. Contini A freeze-fracture study of the human nail plate Arch Dermatol Res 272 1982 117 125
202. J.C. Garson, F. Baltenneck, F. Leroy, C. Riekel, and M. Müller Histological structure of human nail as studied by synchrotron X-ray microdiffraction Cell Mol Biol 46 6 2000 1025 1034
203. G. Achten Histopathology of the nail M. Pierre, The nail 1981 Churchill Livingstone Edinburgh 1 14
204. H.P. Baden The physical properties of nail J Invest Dermatol 55 2 1970 115 122
205. L. Farran, A.R. Ennos, and S.J. Eichhorn The effect of humidity on the fracture properties of human fingernails J Exp Biol 211 Pt 23 2008 3677 3681
206. B.L. Lewis Microscopic studies of fetal and mature nail and surrounding soft tissue AMA Arch Derm Syphilol 70 1954 733 747
207. M. Ramrakhiani Indentation and hardness studies of human nails Indian J Biochem Biophys 15 4 1978 341 343
208. L. Farran, A.R. Ennos, M. Starkie, and S.J. Eichhorn Tensile and shear properties of fingernails as a function of a changing humidity environment J Biomech 42 9 2009 1230 1235
209. Whale baleen picture. < http://en.wikipedia.org/wiki/File:Baleen.jpg >.
210. Pautard F. Calcification of baleen. In: Calcified tissues. Proc second Europ symp; 1965. p. 347-57.
211. D.S. Fudge, L.J. Szewciw, and A.N. Schwalb Morphology and development of blue whale baleen: an annotated translation of Tycho Tullberg's classic 1883 paper Aquat Mamm 35 2 2009 226 252
212. D. Bardack First fossil lamprey: a record from the Pennsylvanian of Illinois Science 162 3859 1968 1265 1267
213. Hagfish. < http://www.ryanphotographic.com/myxinidae.htm >.
214. V. Zintzen, C.D. Roberts, M.J. Anderson, A.L. Stewart, C.D. Struthers, and E.S. Harvey Hagfish predatory behaviour and slime defence mechanism Sci Rep 1 2011 1 6
215. Hagfish slime and the threads. < http://bouncingideas.wordpress.com/2011/10/29/hagfish-slime-is-the-new-spiderweb-silk/ >.
216. D.S. Fudge, N. Levy, S. Chiu, and J.M. Gosline Composition, morphology and mechanics of hagfish slime J Exp Biol 208 Pt 24 2005 4613 4625
217. E.A. Koch, R.H. Spitzer, R.B. Pithawalla, F.A. Castillos, and D.A.D. Parry Hagfish biopolymer: a type I/type II homologue of epidermal keratin intermediate filaments Int J Biol Macromol 17 5 1995 283 292
218. H.P. Baden, L.A. Goldsmith, and L. Lee The importance of understanding the comparative properties of hair and other keratinized tissues in studying disorders of hair A.C. Brown, The first human hair symposium 1974 Medcom Press New York 388 398
219. S.S. Wasko, G.Z. Tay, A. Schwaighofer, C. Nowak, J.H. Waite, and A. Miserez Structural proteins from whelk egg capsule with long range elasticity associated with a solid-state phase transition Biomacromolecules 15 1 2014 30 42
220. T.A. Rawlings Adaptations to physical stresses in the intertidal zone: the egg capsules of neogastropod molluscs Am Zool 39 2 1999 230 243
221. M.W. Denny Biology and the mechanics of the wave-swept environment 1988 Princeton University Press Princeton, NJ
222. N.E. Flower, A.J. Geddes, and K.M. Rudall Ultrastructure of the fibrous protein from the egg capsules of the whelk Buccinum undatum J Ultrastruct Res 26 3 1969 262 273
223. L.J. Gathercole Studies on the protein of the egg capsule of whelks 1969 University of Leeds UK
224. K.J. Whiteley, and I.J. Kaplin The comparative arrangement of microfibrils in orth-, meso-, and paracortical cells of merinowool fibres J Text Inst 68 11 1977 384 386
225. P.A. Guerette, G.Z. Tay, S. Hoon, J.J. Loke, A.F. Hermawan, C.N.Z. Schmitt, and et al. Integrative and comparative analysis of coiled-coil based marine snail egg cases - a model for biomimetic elastomers Biomater Sci 2 5 2014 710
226. H.S. Rapoport, and R.E. Shadwick Mechanical characterization of an unusual elastic biomaterial from the egg capsules of marine snails (Busycon spp.) Biomacromolecules 3 1 2002 42 50
227. S.S. Wasko Biochemistry and structure-function relationships in the proteinaceous egg capsules of Busycotypus canaliculatus 2010 UC Santa Barbara US
228. K. Gregg, S.D. Wilton, D.A.D. Parry, and G.E. Rogers A comparison of genomic coding sequences for feather and scale keratins: structural and evolutionary implications EMBO J 3 1 1984 175 178
229. W.T. Astbury, and T.C. Marwick X-ray interpretation of the molecular structure of feather keratin Nature 130 3278 1932 309 310
230. K.M. Rudall X-ray studies of the distribution of protein chain types in the vertebrate epidermis Biochim Biophys Acta 1 1947 549 562
231. Leonardo da V. Codex on the flight of birds, held Bibl. R. Turin, Italy, 1505.
232. K.Y. Wang The swallows make nests by clay: birds and their breeding 1998 Changchun Press Changchun, China
233. T. Bachmann, J. Emmerlich, W. Baumgartner, J.M. Schneider, and H. Wagner Flexural stiffness of feather shafts: geometry rules over material properties J Exp Biol 215 3 2012 405 415
234. A. Ennos, J.R.E. Hickson, and A. Roberts Functional morphology of the vanes of the flight feathers of the pigeon Columba livia J Exp Biol 198 Pt 5 1995 1219 1228
235. A. Lucas, and P. Stettenheim Avian anatomy-integument 1972 US Department of Agriculture Washington, DC
236. P.P. Purslow, and J.F.V. Vincent Mechanical properties of primary feathers from the pigeon J Exp Biol 72 1978 251 260
237. F.B. Gill Ornithology 2nd ed. 1994 W.H. Freeman and Company New York
238. D.G. Crenshaw Design and materials of feather shafts: very light, rigid structures J Biomech 13 2 1980 199
239. T. Lingham-Soliar, R.H.C. Bonser, and J. Wesley-Smith Selective biodegradation of keratin matrix in feather rachis reveals classic bioengineering Proc Biol Sci 277 1685 2010 1161 1168
240. T. Lingham-Soliar, and N. Murugan A new helical crossed-fibre structure of β-keratin in flight feathers and its biomechanical implications PLoS ONE 8 6 2013
241. W. Corning, and A. Biewener In vivo strains in pigeon flight feather shafts: implications for structural design J Exp Biol 201 Pt 22 1998 3057 3065
242. J.R. Usherwood, T.L. Hedrick, C.P. McGowan, and A.A. Biewener Dynamic pressure maps for wings and tails of pigeons in slow, flapping flight, and their energetic implications J Exp Biol 208 Pt 2 2005 355 369
243. H. Hertel Structure, form, movement 1966 Reinhold Publishing Corp New York
244. G.D. Macleod Mechanical properties of contour feathers J Exp Biol 87 1980 65 71
245. A.H. Brush, and J.A. Wyld Molecular organization of avian epidermal structures Comp Biochem Physiol B 73 2 1982 313 325
246. C. Earland, P.R. Blakey, and J.G.P. Stell Molecular orientation of some keratins Nature 196 1962 1287 1291
247. C. Earland, P.R. Blakey, and J.G. Stell Studies on the structure of keratin. IV. The molecular structure of some morphological components of keratins Biochim Biophys Acta 6 1962 268 274
248. G.J. Cameron, T.J. Wess, and R.H.C. Bonser Young's modulus varies with differential orientation of keratin in feathers J Struct Biol 143 2 2003 118 123
249. S. Pabisch, S. Puchegger, H.O.K. Kirchner, I.M. Weiss, and H. Peterlik Keratin homogeneity in the tail feathers of Pavo cristatus and Pavo cristatus mut. alba J Struct Biol 172 3 2010 270 275
250. Z.Q. Liu, D. Jiao, M.A. Meyers, and Z.F. Zhang Structure and mechanical properties of naturally occurring lightweight foam-filled cylinder - the peacock's tail coverts shaft and its components Acta Biomater 17 2015 137 151
251. R.H. Bonser, and J.W. Farrent Influence of hydration on the mechanical performance of duck down feathers Br Poult Sci 42 2 2001 271 273
252. D.H. Clayton, and P. Cotgreave Relationship of bill to grooming behavior in birds Anim Behav 47 1 1994 195 201
253. A.U. Luester Manual of Pirrot behavior 2006 Wiley Blackwell Publishing
254. A.E. Rupley Manual de clínica aviária 1999 Português Brasileiro São Paulo
255. Y. Seki, B. Kad, D. Benson, and M.a. Meyers The toucan beak: structure and mechanical response Mater Sci Eng C 26 8 2006 1412 1420
256. Y. Seki, S.G. Bodde, and M.a. Meyers Toucan and hornbill beaks: a comparative study Acta Biomater 6 2 2010 331 343
257. A. Lin, and M.A. Meyers Growth and structure in abalone shell Mater Sci Eng A 390 1-2 2005 27 41
258. R.E. Chapman Hair, wool, quill, nail, claw, hoof and horn J. Bereither-Hahn, G.A. Matoltsy, K. Sylvia-Richards, Biology of the integument, vertebrates vol. 2 1986 Springer-Verlag Berlin/Heidelberg/New York 293 312
259. W.E. Clark The problem of the claw in primates Proc Zool Soc Lond 106 1 1936 1 24
260. E.E. Thorndike A microscopic study of the marmoset claw and nail Am J Phys Anthropol 28 3 1968 247 261
261. R.M. Alexander, G.M.O. Maloiy, R. Njau, and A.S. Jayes Mechanics of running of the ostrich (Struthio camelus) J Zool 187 2 2009 169 178
262. R.H.C. Bonser Hydration sensitivity of ostrich claw keratin J Mater Sci Lett 21 2002 1563 1564
263. R.H.C. Bonser The Young's modulus of ostrich claw keratin J Mater Sci Lett 19 2000 1039 1040
264. D.H. Leach, and G.C. Zoerb Mechanical properties of equine hoof wall tissue Am J Vet Res 44 11 1983 2190 2194
265. J.E. Douglas, C. Mittal, J.J. Thomason, and J.C. Jofriet The modulus of elasticity of equine hoof wall: implications for the mechanical function of the hoof J Exp Biol 199 Pt 8 1996 1829 1836
266. J.A. Wyld, and A.H. Brush Keratin diversity in the reptilian epidermis J Exp Zool 225 3 1983 387 396
267. J.A. Wyld, and A.H. Brush The molecular heterogeneity and diversity of reptilian keratins J Mol Evol 12 4 1979 331 347
268. P.F.A. Maderson Some developmental problems of the reptilian integument C. Gans, F. Billett, P.F.A. Maderson, Biology of the reptilia 1985 John Wiley & Sons 523 598
269. L. Landmann The skin of reptiles: epidermis and dermis J. Bereither-Hahn, G.A. Matoltsy, K. Sylvia-Richards, Biology of the integument, vertebrates vol. 2 1986 Springer-Verlag Berlin/Heidelberg/New York 150 187
270. R.H. Sawyer, T. Glenn, J.O. French, B. Mays, R.B. Shames, G.L. Barnes Jr, and et al. The expression of beta (β) keratins in the epidermal appendages of reptiles and birds Am Zool 40 4 2000 530 539
271. L. Alibardi, and R.H. Sawyer Immunocytochemical analysis of beta (β) keratins in the epidermis of chelonians, lepidosaurians, and archosaurians J Exp Zool 293 1 2002 27 38
272. B.K. Filshie, and G.E. Rogers The fine structure of α-keratin J Mol Biol 3 6 1961 784 786
273. N.J. Alexander Comparison of α and β keratin in reptiles Z Zellforsch 110 2 1970 153 165
274. L. Alibardi, and M. Toni Cytochemical, biochemical and molecular aspects of the process of keratinization in the epidermis of reptilian scales Prog Histochem Cytochem 40 2 2006 73 134
275. N.J. Alexander, and P.F. Parakkal Formation of α- and β-type keratin in lizard epidermis during the molting cycle Z Zellforsch 101 1 1969 72 87
276. M. Toni, and L. Alibardi Alpha- and beta-keratins of the snake epidermis Zoology 110 1 2007 41 47
277. R.I.C. Spearman The epidermis of the gopher tortoise Testudo polyphemus (Daudin) Acta Zool 50 1969 1 9
278. A.M. Bauer, A.P. Russell, and R.E. Shadwick Mechanical properties and morphological correlates of fragile skin in gekkonid lizards J Exp Biol 145 1989 79 102
279. M.-C.G. Klein, and S.N. Gorb Epidermis architecture and material properties of the skin of four snake species J R Soc Interface 9 76 2012 3140 3155
280. L. Landmann Keratin formation and barrier mechanisms in the epidermis of Natrix natrix (Reptilia: Serpentes): an ultrastructural study J Morphol 162 1 1979 93 126
281. R.Z. Wang, and S. Weiner Strain-structure relations in human teeth using Moiré fringes J Biomech 31 2 1998 135 141
282. H. Fong, M. Sarikaya, S.N. White, and M.L. Snead Nano-mechanical properties profiles across dentin-enamel junction of human incisor teeth Mater Sci Eng C 7 2 2000 119 128
283. R. Zangerl The turtle shell C. Gans, Biology of the reptilia: morphology A vol. 1 1969 Academic Press London, New York 311 339
284. G.O. Cherepanov Ontogenetic development of the shell in Trionix sinensis (Trionichidae, Testudinata) and some questions on the nomenclature of bony plates Russ J Herpetol 2 2 1995 129 133
285. S.F. Gilbert, G.A. Loredo, A. Brukman, and A.C. Burke Morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution Evol Dev 3 2 2001 47 58
286. L. Dalla Valle, F. Michieli, F. Benato, T. Skobo, and L. Alibardi Molecular characterization of alpha-keratins in comparison to associated beta-proteins in soft-shelled and hard-shelled turtles produced during the process of epidermal differentiation J Exp Zool Part B: Mol Dev Evol 320 2013 428 441
287. L. Alibardi Ultrastructural immunolocalization of alpha-keratins and associated beta-proteins (beta-keratins) suggests a new interpretation on the process of hard and soft cornification in turtle epidermis Micron 52-53 2013 8 15
288. B. Achrai, B. Bar-On, and H.D. Wagner Bending mechanics of the red-eared slider turtle carapace J Mech Behav Biomed Mater 30 2014 223 233
289. H. Rhee, M.F. Horstemeyer, Y. Hwang, H. Lim, H. El Kadiri, and W. Trim A study on the structure and mechanical behavior of the Terrapene carolina carapace: a pathway to design bio-inspired synthetic composites Mater Sci Eng C 29 8 2009 2333 2339
290. K. Balani, R.R. Patel, A.K. Keshri, D. Lahiri, and A. Agarwal Multi-scale hierarchy of Chelydra serpentina: microstructure and mechanical properties of turtle shell J Mech Behav Biomed Mater 4 7 2011 1440 1451
291. R. Damiens, H. Rhee, Y. Hwang, S.J. Park, Y. Hammi, H. Lim, and et al. Compressive behavior of a turtle's shell: experiment, modeling, and simulation J Mech Behav Biomed Mater 6 2012 106 112
292. B. Achrai, and H.D. Wagner Micro-structure and mechanical properties of the turtle carapace as a biological composite shield Acta Biomater 9 4 2013 5890 5902
293. W. Zhang, C. Wu, C. Zhang, and Z. Chen Numerical study of the mechanical response of turtle shell J Bionic Eng 9 3 2012 330 335
294. W. Zhang, C. Wu, C. Zhang, and Z. Chen Microstructure and mechanical property of turtle shell Theor Appl Mech Lett 2 1 2012 014009
295. R.I.C. Spearman The keratinization of epidermal scales, feathers and hairs Biol Rev 41 1 1966 59 96
296. M. Briggs, and P. Briggs The Encyclopedia of world wildlife 2006 Paragon Books
297. Pangolin, aomor function. < http://www.animal-space.net/2010/12/lion-vs-pangolin.html >.
298. Pangolin armor coat. < http://commons.wikimedia.org/wiki/File:Coat-of-Pangolin-scales.JPG?uselang=zh-cn >.
299. African tree pangolin. < http://commons.wikimedia.org/wiki/File:Manis-tricuspis-San-Diego-Zoo-03.2012.jpg >.
300. Chinese ground pangolin. < http://commons.wikimedia.org/wiki/File:Zoo-Leipzig---Tou-Feng.jpg >.
301. J. Tong, L.-Q. Ren, and B.-C. Chen Chemical constitution and abrasive wear behaviour of pangolin scales J Mater Sci Lett 14 20 1995 1468 1470
302. M.E. Heath Manis pentadactyla Am Soc Mammal 414 1992 1 6
303. J. Tong, Y.H. Ma, L.Q. Ren, and J.Q. Li Tribological characteristics of pangolin scales in dry sliding J Mater Sci Lett 19 7 2000 569 572
304. J.F.V. Vincent, O.A. Bogatyreva, N.R. Bogatyrev, A. Bowyer, and A.-K. Pahl Biomimetics: its practice and theory J R Soc Interface 3 9 2006 471 482
305. Web of Science. Increase of publications and citations for 'bioinspired materials' since 1996. Web of Science; 2015. < http://apps.webofknowledge.com/CitationReport.do?product=UA&search-mode=CitationReport&SID=3Btq3MDi5Rv8JF5oBG8&page=1&cr-pqid=1&viewType=summary >.
306. W. Yang, I.H. Chen, B. Gludovatz, E.A. Zimmermann, R.O. Ritchie, and M.A. Meyers Natural flexible dermal armor Adv Mater 25 1 2013 31 48
307. J. Banhart Aluminum foams: on the road to real applications MRS Bull 28 4 2003 290 295
308. V.P. Veedu, A. Cao, X. Li, K. Ma, C. Soldano, S. Kar, and et al. Multifunctional composites using reinforced laminae with carbon-nanotube forests Nat Mater 5 6 2006 457 462
309. V.M. Drakonakis, C.N. Velisaris, J.C. Seferis, and C.C. Doumanidis Feather-inspired carbon fiber reinforced polymers with nanofibrous fractal interlayer Polym Compos 2014
310. W.K. Cho, J.A. Ankrum, D. Guo, S.A. Chester, S.Y. Yang, A. Kashyap, and et al. Microstructured barbs on the North American porcupine quill enable easy tissue penetration and difficult removal Proc Natl Acad Sci USA 109 52 2012 21289 21294
311. Industrial wastewater filter technology inspired by nature. Filtrat Sep 2003; 40(1): 18-21.
312. Whalebone inspires filter technology. Filtrat Sep 2007; 44(2): 10.
313. Baleen Filters Pty Ltd. Baleen filters. < http://www.baleenfilters.com/ >.
314. Pinnacle Armor. The dragon skin bodyarmor. < https://en.wikipedia.org/wiki/Dragon-Skin#/media/File:PEO-soldier-Dragonskin.jpg >.
315. Cyclus Manufacture. Pangolin backpack. < http://www.pangolin.com.co/collections/main-collection >.
316. E.F. Banwell, E.S. Abelardo, D.J. Adams, M.A. Birchall, A. Corrigan, A.M. Donald, and et al. Rational design and application of responsive alpha-helical peptide hydrogels Nat Mater 8 7 2009 596 600
317. T. Fu, P.A. Guerette, R.Y. Tan, H. Zhao, L. Schefer, R. Mezzenga, and et al. Biomimetic self-assembly of recombinant marine snail egg capsule proteins into structural coiled-coil units J Mater Chem B 2015