Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Poster: Biopolymers and Biomaterials

CPP 28.5: Poster

Wednesday, March 24, 2010, 17:30–19:00, Poster C

Hierarchies in the structural organization of spider silk - A quantitative combined model — •Roxana Ene, Periklis Papadopoulos, and Friedrich Kremer — Institut für Experimentelle Physik I, Leipzig, Germany

Combined time-resolved mechanical and polarized Fourier-transform infrared measurements allow us to determine the interconnection of the nanocrystal and amorphous phases in major ampullate spider silk in the native and supercontracted state [1]. Crystal stress can be measured from the frequency shift of main-chain vibrations. The results show that in both states of silk a serial arrangement between the crystalline and amorphous phase dominates the nanostructure. However, supercontracted silk shows a different behavior before being stretched because a hydrogen-bonded network is formed in the amorphous phase, due to release of pre-stress and hydrophobic effects. A three-component combined model of crystals in serial arrangement with amorphous chains and a fraction of chains bypassing them can describe all states of spider silk, assuming hydrogen bonding of worm-like chains at low pre-strain [2]. Additionally water permeability of dragline silk is studied by measuring changes in amide deuteration [3]. The results show that the chemical exchange of amide hydrogen occurs in a large fraction of amino acids, including b-sheeted alanine residues, suggesting that also the crystalline regions are accessible to water. [1] P. Papadopoulos, R. Ene, I. Weidner, F. Kremer Macromol. Rapid Commun 30, 851-857 (2009). [2] R. Ene, P. Papadopoulos, F. Kremer, Soft Matter 5, 4568-4574 (2009) [3] R.Ene, P. Papadopoulos, F. Kremer (in preparation)