title: A DNA--silver nanocluster probe that fluoresces upon hybridization.
abstract: DNA-templated silver nanoclusters (DNA/Ag NCs) are an emerging set of fluorophores that are smaller than semiconductor quantum dots and can have better photostability and brightness than commonly used organic dyes. Here we find the red fluorescence of DNA/Ag NCs can be enhanced 500-fold when placed in proximity to guanine-rich DNA sequences. On the basis of this new phenomenon, we have designed a DNA detection probe (NanoCluster Beacon, NCB) that "lights up" upon target binding. Since NCBs do not rely on Forster energy transfer for quenching, they can easily reach high (>100) signal-to-background ratios (S/B ratios) upon target binding. Here, in a separation-free assay, we demonstrate NCB detection of an influenza target with a S/B ratio of 175, a factor of 5 better than a conventional molecular beacon probe. Since the observed fluorescence enhancement is caused by intrinsic nucleobases, our detection technique is simple, inexpensive, and compatible with commercial DNA synthesizers.
authors.affiliation: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Hsin-Chih
authors.initials: HC
authors.lastname: Yeh
authors.forename: Jaswinder
authors.initials: J
authors.lastname: Sharma
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Han
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Martinez
authors.forename: James H
authors.initials: JH
authors.lastname: Werner
mesh_terms: D001667:Binding, Competitive; D004247:DNA / Q000737:chemistry*; D015335:Molecular Probes; D049329:Nanostructures; D009693:Nucleic Acid Hybridization; D012834:Silver / Q000737:chemistry*
chemical_list: D015335:Molecular Probes; D012834:Silver; D004247:DNA