title: Metal-enhanced single-molecule fluorescence on silver particle monomer and dimer: coupling effect between metal particles.
abstract: We prepared silver particle dimers with single Cy5 molecules localized between coupled metal particles. The silver particles with a 20 nm diameter were chemically bound with single-stranded oligonucleotides. The dimers were formed by hybridization with double-length single-stranded oligonucleotides that contained single Cy5 molecules. The image analysis revealed that the single-molecule fluorescence was enhanced 7-fold on the metal monomer and 13-fold on the metal dimer relative to the free Cy5-labeled oligonucleotide in the absence of metal. The lifetimes were shortened on the silver monomers and further shortened on the silver dimers, demonstrating the near-field interaction mechanism of fluorophore with the metal substrate. Finite-difference time-domain (FDTD) calculations were employed to study the distribution of electric field near the metal monomer and dimer. The coupling effect of metal particle on the fluorescence enhancement was discussed.
authors.affiliation: Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, Maryland 21201, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Fu
authors.forename: Mustafa H
authors.initials: MH
authors.lastname: Chowdhury
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D001483:Base Sequence; D002232:Carbocyanines; D019281:Dimerization; D005456:Fluorescent Dyes; D053768:Metal Nanoparticles; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D012834:Silver; D008625:Tiopronin
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D009841:Oligonucleotides; C085321:cyanine dye 5; D012834:Silver; D008625:Tiopronin