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SYMR: Symposium Nuclear Magnetic Resonance: from Applications in Condensed-Matter Physics to New Frontiers

SYMR 7: Biopolymers and Biomaterials

SYMR 7.8: Vortrag

Mittwoch, 24. März 2010, 16:15–16:30, H37

Real-time in-situ study of oligo(ethylene glycol) reordering dynamics and immersion effects using PMIRRAS — •Stefan Zorn, Alexander Gerlach, and Frank Schreiber — Institut für Angewandte Physik, Universität Tübingen, Germany

Owing to their high importance in biological and medical applications, e.g. as tethering group for specific binding or, importantly, for passivation of surfaces against unspecific protein absorption, oligo(ethylene glycols) have been the subject of extensive studies. SFG and IR studies revealed strong interactions of water and SAM and strong conformational changes [1]. However, the exact mechanism of protein repulsion is still not fully understood. Here we present a real-time in-situ study of the reordering of the SAM structure during its growth in solution. Using a home build liquid cell with a very thin solution layer (ca. 1 um) we were able to monitor changes in conformation in real time in aqueous environment. With increasing surface coverage there is a change from an amorphous structure with mixed all-trans und helical conformation to a high ordered structure with predominantly helical conformation. A comparison with spectra measured in air shows differences in conformation due to the interaction with water which are more pronounced for lower surface coverage. We also monitored the stability of the SAM over long periods of time and the change in conformation with increasing temperature in solution. Our results shed new light onto the role of water on the structure and protein resistance of OEG SAMs and help to explain the conflicting results in various recent studies.

[1] M.W.A. Skoda et al., Langmuir 23 (2007) 970.