title: Quenching and blinking of fluorescence of a single dye molecule bound to gold nanoparticles.
abstract: A fluorescein derivative (SAMSA) bound to gold nanoparticles of different diameters is investigated by time-resolved fluorescence at the single molecule level in a wide dynamic range, from nanosecond to second time scale. The significant decrease of both SAMSA excited state lifetime and fluorescence quantum yield observed upon binding to gold nanoparticles can be essentially traced back to an increase of the nonradiative deactivation rate, probably due to energy transfer, that depends on the nanoparticle size. A slow single molecule fluorescence blinking, in the ms time scale, has a marked dependence on the excitation intensity both under single and under two photon excitation. The blinking dynamics is limited by a low probability nonlinear excitation to a high energy state from which a transition to a dark state occurs. The results point out a strong coupling between the vibro-electronic configuration of the dye and the plasmonic features of the metal nanoparticles that provide dye radiationless deactivation channels on a wide dynamic range.
authors.affiliation: Laboratory for Advanced BioSpectroscopy (LABS), INFM-CNR, Physics Department, University of Milano-Bicocca, Milano I-20126, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Cannone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Chirico
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Bizzarri
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cannistraro
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D019793:Fluorescein / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D015394:Molecular Structure; D010316:Particle Size; D013050:Spectrometry, Fluorescence; D013387:Succinic Anhydrides / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D013387:Succinic Anhydrides; C024249:S-acetylmercaptosuccinic anhydride; D006046:Gold; D019793:Fluorescein