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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: POSTERS Single Molecules, Biopolymers, Membranes
CPP 9.2: Poster
Montag, 25. Februar 2008, 16:45–19:00, Poster A
Gold Nanoparticles Decorated with Oligo(ethylene glycol) Thiols: The Effect of Salt Nature on the Stability of Colloid-Protein Mixtures — •Fajun Zhang1, Maximilian W. A. Skoda1,2, Robert M. J. Jacobs2, Stefan Zorn1, Richard A. Martin3, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany — 2CRL, University of Oxford, UK — 3Department of Physics, University of Bath, UK
The stability of mixtures of oligo(ethylene glycol) (OEG) thiol self-assembled monolayer protected gold colloids and globular proteins in solution, depends strongly on the nature of added salts. UV-vis spectroscopy was used to study the stability of the mixtures by monitoring the time dependence of the flocculation [1]. It was shown that the OEG-protected gold colloid solution is stable in the presence of NaCl, NaSCN, MgCl2, but loses its stability on addition of Na2SO4. In the mixtures of colloid and protein, the colloids lose their stability and form aggregates upon adding protein above a critical concentration, c*, due to the depletion effect [1]. Adding NaCl or Na2SO4 to the mixtures enhances the colloid aggregation; NaSCN stabilizes the solution, and MgCl2 results in a long induction time before aggregation. The observed salt nature effects follow the ``Hofmeister series'' and are discussed based on the salting-in or salting-out effect as well as the ion-absorption effect. The salt nature effect is planned to be further studied by SAXS. [1] F. Zhang, et al., J. Phys. Chem. B. 2007, 111, 251. J. Phys. Chem. A. 2007, DOI: 10.1021/jp074293v. Euro. Biophys. J. Submitted.