Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 61: Plasmonics and Nanooptics VII: Applications and Other Aspects
HL 61.12: Vortrag
Mittwoch, 22. März 2017, 17:45–18:00, TRE Ma
Monitoring of structural changes of polypeptides using resonant surface enhanced infrared spectroscopy — •Rostyslav Semenyshyn1, Mario Hentschel1, Jochen Vogt2, Christian Huck2, Christoph Stanglmair3, Claudia Pacholski3, Frank Neubrech1,2, and Harald Giessen1 — 14th Physics Institute, University of Stuttgart — 2Kirchhoff Institute for Physics, University of Heidelberg — 3Max Planck Institute for Intelligent Systems, Stuttgart
Infrared (IR) vibrational spectroscopy is a powerful tool for the identification of chemical and structural composition of molecules. Its detection limit can be improved by several orders of magnitude using surface-enhanced IR absorption (SEIRA) with resonant nanoantennas. Here, we demonstrate the capability of SEIRA for the ultra-sensitive detection of minute amounts of a polypeptide, namely poly-L-lysine (PLL). Furthermore, we applied SEIRA to monitor structural changes of the molecules introduced by injecting sodium dodecyl sulfate as well as varying the pD value. For this purpose, we functionalized nanoantenna arrays with mercaptoundecanoic acid (MUA) and mercaptoundecanol (MUoL) in order to bind PLL molecules to the gold surface. The combination of MUA and MUoL ensures a sufficient flexibility, allowing for structural changes. Such changes are detected based on a detailed analysis of the amide-I vibrations. Hence, we tuned the plasmonic resonances of nanoantennas to the amide-I band of PLL and performed in-vitro SEIRA measurements in D2O based solutions. Following this approach, we monitored the reversible change between α-helix and β-sheet structural states of PLL in low concentrations.