Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Nanoparticles I

CPP 8.3: Talk

Monday, March 23, 2009, 11:00–11:15, ZEU 114

Kinetic study of binding of multivalent ligands on size selected gold nanoparticles — •Suguna Perumal, Andreas Hofmann, Christina Graf, and Eckart Rühl — Physikalische und Theoretische Chemie, Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin

A kinetics study of binding of multivalent ligands on different kinds of nanoparticles is presented. The enhanced binding of multiple ligands in one entity to multiple receptors is known as the multivalency effect. Flexible thiol functionalized multivalent ligands are synthesized by using reported procedures. Pyrene bound nanoparticles are prepared by wet colloidal chemistry and characterized by transmission electron microscopy. The multivalency effects are investigated by exchanging pyrene bound to gold nanoparticles with multivalent ligands and studying this process via fluorescence spectroscopy. The fluorescence of the pyrene moiety is completely quenched when it is directly bound to gold nanoparticles. It recovers completely after desorption from nanoparticles after an exchange with mono- or multivalent ligands. The change of the fluorescence intensity of the pyrene moiety is measured as a function of time. Multivalency effects are observed by comparing the rate constants of monovalent and di- or trivalent thiol ligands. However, no enhancement effects are observed between trivalent and divalent thiol ligands on gold nanoparticles. Hence, we assume that only two thiol groups are binding in case of the trivalent ligands. Further, the influence of the particle size on the exchange kinetics is discussed.