Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 36: Poster: Nanoparticles and Composite Materials
CPP 36.21: Poster
Mittwoch, 16. März 2011, 17:00–19:00, P2
Gold Nanoparticles Decorated with oligo(ethylene glycol) Thiols: Surface Charges and their Influence on Protein Resistance — •Moritz Schollbach1, Maximilian W. A. Skoda2, Robert M. J. Jacobs3, Fajun Zhang1, and Frank Schreiber1 — 1IAP Universität Tübingen — 2ISIS Rutherford Appleton Laboratory UK — 3CRL University of Oxford UK
Protein resistant behavior of oligo(ethylene glycol) thiol self assembled monolayers (OEG SAM) on gold surfaces [1] makes them interesting for various applications. In previous studies we investigated the resistance to adsorption of bovine serum albumin (BSA) on a model system of OEG SAM coated gold nanoparticles (AuNP) [2]. Gold colloids allow easy observation because protein repulsion leads to aggregation via a depletion-attraction effect [3]. By extending this study to other proteins, we found that surface charges play a crucial role. Zeta potential (ζ) measurements of AuNP show negative values, corresponding to a low net negative surface charge. Added negatively charged protein (BSA) does not change ζ. The size distribution, obtained by dynamic light scattering (DLS), shows separate peaks for colloid and BSA. In contrast, adding the positive charged Lysozyme (LYZ) raises ζ, resulting in a charge inversion for higher LYZ concentrations. For samples with ζ ≈ 0 the size distribution shows aggregates of AuNP. These results indicate that LYZ can adsorb on the AuNP, neutralizing the surface charge and destabilizing the system. [1] F. Schreiber, J. Phys.: M. 16, 2004, R881. [2] F. Zhang et al. J. Phys. Chem. A, 111, 2007, 12229 [3] F. Zhang et al. Eur. Biophys. J., 37, 2008, 551