title: Fluorescence enhancement of fluorophores tethered to different sized silver colloids deposited on glass substrate.
abstract: We studied fluorescence enhancements of fluorescein tethered to silver colloids of different size. Thiolated 23-mer oligonucleotide (ss DNA-SH) was bound selectively to silver colloids deposited on 3-aminopropyltriethoxysilane (APS)-treated quartz slides. Fluorescein-labeled complementary oligonucleotide (ss Fl-DNA) was added in an amount significantly lower than the amount of unlabeled DNA tethered to the colloids. The hybridization kinetics, observed as an increase in fluorescence emission, on small (30-40 nm) and large (> 120 nm) colloids were similar. However, the final fluorescence intensity of the sample with large colloids was about 50% higher than that observed for the sample with small colloids. The reference sample without ss DNA-SH was used to estimate the fluorescence enhancements of fluorescein tethered to the small colloids (E = 2.7) and to the large colloids (E = 4.1) due to its steady fluorescence signal. The proposed method, based on controlled hybridization with minimal amount of fluorophore labeled ss DNA, can be used to reliably estimate the fluorescence enhancements on any silver nanostructures.
authors.affiliation: Center for Fluorescence Spectroscopy, University of Maryland at Baltimore, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201, USA. joanna@cfs.umbi.umd.edu
authors.forename: Joanna
authors.initials: J
authors.lastname: Lukomska
authors.forename: Joanna
authors.initials: J
authors.lastname: Malicka
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Zoya
authors.initials: Z
authors.lastname: Leonenko
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D003102:Colloids; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000648:ultrastructure; D005456:Fluorescent Dyes; D005898:Glass; D018625:Microscopy, Atomic Force; D012680:Sensitivity and Specificity; D012834:Silver; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D003102:Colloids; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D012834:Silver