Silver atom and strand numbers in fluorescent and dark Ag:DNAs

Schultz, Danielle M.; Gwinn, E. G.

doi:10.1039/c2cc17675k

Cited by 127 publications

(210 citation statements)

References 24 publications

(14 reference statements)

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“…The second HPLC round used 1,1,1,3,3,3 hexafluoro-2-propanol/triethylamine as the ion-pairing agent to ensure sufficient ionization rates for high sensitivity MS. 32 MS confirms that the cluster stabilized by the modified Ag 15 -DNA host strand contains 15 silver atoms ( Figure S4, Supporting Information). The eluting Ag 15 -DNA is estimated to be g70 ( 1% pure.…”

Section: Resultssupporting

confidence: 75%

Atomically Precise Arrays of Fluorescent Silver Clusters: A Modular Approach for Metal Cluster Photonics on DNA Nanostructures

et al. 2015

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The remarkable precision that DNA scaffolds provide for arraying nanoscale optical elements enables optical phenomena that arise from interactions of metal nanoparticles, dye molecules, and quantum dots placed at nanoscale separations. However, control of ensemble optical properties has been limited by the difficulty of achieving uniform particle sizes and shapes. Ligand-stabilized metal clusters offer a route to atomically precise arrays that combine desirable attributes of both metals and molecules. Exploiting the unique advantages of the cluster regime requires techniques to realize controlled nanoscale placement of select cluster structures. Here we show that atomically monodisperse arrays of fluorescent, DNA-stabilized silver clusters can be realized on a prototypical scaffold, a DNA nanotube, with attachment sites separated by <10 nm. Cluster attachment is mediated by designed DNA linkers that enable isolation of specific clusters prior to assembly on nanotubes and preserve cluster structure and spectral purity after assembly. The modularity of this approach generalizes to silver clusters of diverse sizes and DNA scaffolds of many types. Thus, these silver cluster nano-optical elements, which themselves have colors selected by their particular DNA templating oligomer, bring unique dimensions of control and flexibility to the rapidly expanding field of nano-optics.

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Section: Resultssupporting

confidence: 75%

Atomically Precise Arrays of Fluorescent Silver Clusters: A Modular Approach for Metal Cluster Photonics on DNA Nanostructures

et al. 2015

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“…Recent studies have identified dimeric strand-cluster conjugates by electrospray ionization mass spectrometry. 63 While droplet evaporation might promote strand association through solute concentration, our studies indicate that such species are stable in dilute solution conditions.…”

Section: Discussionmentioning

confidence: 74%

“…Recent mass spectral studies have also identified cluster-DNA conjugates with similar amounts of silver. 63 …”

Section: Resultsmentioning

confidence: 99%

Silver Clusters as Both Chromophoric Reporters and DNA Ligands

et al. 2013

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Molecular silver clusters conjugated with DNA act as analyte sensors. Our studies evaluate a type of cluster-laden DNA strand whose structure and silver stoichiometry changes with hybridization. The sensor strand integrates two functions: the 3′ region binds target DNA strands through base recognition while the 5′ sequence C3AC3AC3TC3A favors formation of a near infrared absorbing and emitting cluster. This precursor form exclusively harbors an ~11 silver atom cluster that absorbs at 400 nm and that condenses its single-stranded host. The 3′ recognition site associates with a complementary target strand, thereby effecting a 330 nm red-shift in cluster absorption and a background-limited recovery of cluster emission at 790 nm. One factor underlying these changes is sensor unfolding and aggregation. Variations in salt and oligonucleotide concentrations control cluster development by influencing DNA association. Structural studies using fluorescence anisotropy, fluorescence correlation spectroscopy, and size exclusion chromatography show that the sensor-cluster conjugate opens and subsequently dimerizes with hybridization. A second factor contributing to the spectral and photophysical changes is cluster transformation. Empirical silver stoichiometries are preserved through hybridization, so hybridized, dimeric near infrared conjugates host twice the amount of silver in relation to their violet absorbing predecessors. These DNA structure and net silver stoichiometry alterations provide insight into how DNA-silver conjugates recognize analytes.

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“…20 74,75 Analogously, reduced silver clusters with near-infrared absorption and emission cross-link two cytosine-rich strands and form intermolecular dimers in dilute solutions with 500 nM oligonucleotide concentrations. 31,76,77 On the other hand, DNA strands mold their silver cluster adducts. The nucleobases anchor silver clusters, and cytosine forms the strongest complexes.…”

Section: ■ Discussionmentioning

confidence: 99%

Ten-Atom Silver Cluster Signaling and Tempering DNA Hybridization

et al. 2015

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Silver clusters with ∼10 atoms are molecules, and specific species develop within DNA strands. These molecular metals have sparsely organized electronic states with distinctive visible and near-infrared spectra that vary with cluster size, oxidation, and shape. These small molecules also act as DNA adducts and coordinate with their DNA hosts. We investigated these characteristics using a specific cluster-DNA conjugate with the goal of developing a sensitive and selective biosensor. The silver cluster has a single violet absorption band (λ(max) = 400 nm), and its single-stranded DNA host has two domains that stabilize this cluster and hybridize with target oligonucleotides. These target analytes transform the weakly emissive violet cluster to a new chromophore with blue-green absorption (λ(max) = 490 nm) and strong green emission (λ(max) = 550 nm). Our studies consider the synthesis, cluster size, and DNA structure of the precursor violet cluster-DNA complex. This species preferentially forms with relatively low amounts of Ag(+), high concentrations of the oxidizing agent O2, and DNA strands with ≳20 nucleotides. The resulting aqueous and gaseous forms of this chromophore have 10 silvers that coalesce into a single cluster. This molecule is not only a chromophore but also an adduct that coordinates multiple nucleobases. Large-scale DNA conformational changes are manifested in a 20% smaller hydrodynamic radius and disrupted nucleobase stacking. Multidentate coordination also stabilizes the single-stranded DNA and thereby inhibits hybridization with target complements. These observations suggest that the silver cluster-DNA conjugate acts like a molecular beacon but is distinguished because the cluster chromophore not only sensitively signals target analytes but also stringently discriminates against analogous competing analytes.

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Silver atom and strand numbers in fluorescent and dark Ag:DNAs

Cited by 127 publications

References 24 publications

Atomically Precise Arrays of Fluorescent Silver Clusters: A Modular Approach for Metal Cluster Photonics on DNA Nanostructures

Atomically Precise Arrays of Fluorescent Silver Clusters: A Modular Approach for Metal Cluster Photonics on DNA Nanostructures

Silver Clusters as Both Chromophoric Reporters and DNA Ligands

Ten-Atom Silver Cluster Signaling and Tempering DNA Hybridization

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