title: Kinetics study of the binding of multivalent ligands on size-selected gold nanoparticles.
abstract: The effect of ligand multivalency and nanoparticle size on the binding kinetics of thiol ligands on gold nanoparticles is investigated by exchanging monovalently bound pyrene on gold nanoparticles against flexible mono- and multivalent thiol ligands. Variable-sized gold nanoparticles of 2.2 ± 0.4, 3.2 ± 0.7, and 4.4 ± 0.9 nm diameter are used as substrates. The particles are coated by thiol functionalized pyrene ligands and the binding kinetics of the thiol ligands is studied by time-resolved fluorescence spectroscopy. The effect of multivalency on the binding kinetics is evaluated by comparing the rate constants of ligands of different valency. This comparison reveals that the multivalent ligands are exchanging substantially more rapidly than the monovalent ones. A particle size dependence of the rate constants is also observed, which is used to derive structural information on the binding of the mono- and multivalent ligands to the nanoparticle surface.
authors.affiliation: Physikalische und Theoretische Chemie, Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany.
authors.forename: Suguna
authors.initials: S
authors.lastname: Perumal
authors.forename: Andreas
authors.initials: A
authors.lastname: Hofmann
authors.forename: Norman
authors.initials: N
authors.lastname: Scholz
authors.forename: Eckart
authors.initials: E
authors.lastname: Rühl
authors.forename: Christina
authors.initials: C
authors.lastname: Graf
mesh_terms: D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011721:Pyrenes; D013050:Spectrometry, Fluorescence; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D008024:Ligands; D011721:Pyrenes; D013438:Sulfhydryl Compounds; D006046:Gold; C030984:pyrene