Regensburg 2007 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 35: SYBM Bioinspired Materials
MM 35.19: Poster
Thursday, March 29, 2007, 18:45–20:45, H16
Grazing-incidence X-ray scattering investigation on the structure of thin films of recombinant spider silk proteins — •E. Metwalli1, U. Slotta2, C. Darko1, S. Roth3, T. Scheibel2, and C. Papadakis1 — 1Physikdepartment E13, TU München, 85747 Garching — 2Chemiedepartment, TU München — 3HASYLAB at DESY, Hamburg
Protein immobilization on solid supports is important for many potential applications such as protein microarrays. Recombinant spider silk proteins offer the possibility to control the molecular sequence and thus the material properties [1]. Spin-coating was used to prepare films of synthetic spider silk protein derived from the garden spider's (Araneus diadematus) dragline silk protein ADF-4. A transition from alfa-helix to beta-sheet rich structures upon methanol treatment of the films has been detected by IR and circular dichroism spectroscopies [2]. We present here direct evidence for this structural transformation. We have observed crystalline domains within the films after treatment and could determine their size and shape using grazing-incidence X-ray diffraction (GIXD) and small-angle scattering (GISAXS). GIXD showed Bragg peaks from beta-sheet poly-alanine crystallites having a size of 8 nm. GISAXS confirmed the presence of crystallites of this size. We conclude that the protein film structure after the methanol treatment consists mainly of crystalline beta-sheet rich regions embedded in an amorphous matrix. [1] Scheibel T., Current Opinion in Biotechnology 16, 427 (2005). [2] Hummerich D., Slotta U., and Scheibel T., Applied Phys. A-Materials Sci. & Processing 82, 219 (2006).