Regensburg 2013 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 14: Biomaterials and Biopolymers I (joint with CPP)
BP 14.4: Vortrag
Dienstag, 12. März 2013, 10:30–10:45, H34
Response of major ampullate silk of Nephila pilipes to pressure and tensile stress as measured by FTIR spectroscopy — •Markus Anton1, Wilhelm Kossack1, Christof Gutsche1, Roxana Figuli2, Periklis Papadopoulos3, and Friedrich Kremer1 — 1Universität Leipzig, Institut für Experimental Physik I, Linnéstraße 5, 04103 Leipzig, Germany — 2Karlsruher Institut für Technologie, Institut für Technische Chemie und Polymerchemie, Engesserstraße 18, 76128 Karlsruhe, Germany — 3Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
Nanocrystals composed mainly of β-sheet polyalanine are reposonsible for the high toughness of major ampullate (dragline) spider silk. Fourier-Transform infrared (FTIR) spectroscopy is employed to study their response to (i) uniaxial stress and (ii) hydrostatic pressure. In the former a red shift and in the latter a blue shift of the vibration of polyalanine β-sheets at 965 cm−1 is observed. In both cases a linear dependence is evident, which bends off for hydrostatic pressure greater than 1.4 GPa and is fully reversible up to 7 GPa. The seamless connection of negative and positive pressure regimes corroborate quantitatively our structural model of spider silk [P. Papadopoulos et al., Eur. Phys. J. E 24 (2007) 193, P. Papadopouloset al., Colloid Polym. Sci. 287 (2009) 231, R. Ene et al., Soft Matter 5 (2009) 4568] as composed of pre-stressed alanine-rich nanocrystals embedded in a glycine-rich amorphous matrix. It is also confirmed that nanocrystals withstand high pressures without undergoing structural transition or deteriorating their mechanical properties.