Single‐Molecule Characterization of Near‐Infrared‐Emitting Silver Nanoclusters

Hooley, E.; Paolucci, Valentina; Liao, Zhiyu; Carro‐Temboury, Miguel R.; Vosch, Tom

doi:10.1002/adom.201500048

Cited by 15 publications

(12 citation statements)

References 54 publications

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“…Cytosine dominates this sequence with 11 of the 14 nucleobases, but they must be separated to avoid a mixture of clusters (Figure S4). , We suggest that the three cytosine tracts in C 4 AC 4 TC 3 G are collective subunits. When only a single cytosine is eliminated or replaced in any of the tracts, the 490 nm absorption is extinguished, so the cluster binding site is compromised (Figures A and S3).…”

Section: Discussionmentioning

confidence: 76%

A DNA-Encapsulated Silver Cluster and the Roles of Its Nucleobase Ligands

et al. 2018

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Silver clusters consisting of ∼10 atoms are readily bound by and encapsulated within DNA strands to yield strong absorption and emission. The coordination environments, however, are poorly understood, so cluster adducts can only be empirically tuned. This work describes the C4AC4TC3G strand that templates a particular cluster adduct. Its sequence has three types of nucleobases with distinct rolestracts of cytosines that collectively coordinate the cluster, thymine acting as a junction in the overall strand, and the adenine/guanine pair that exclusively forms the cluster. In relation to the native oligonucleotide, the DNA–silver cluster complex diffuses faster and is more compact, thus suggesting that the strands fold because of the cluster. The Ag10 6+ adduct emits with λex/λem = 490/540 nm, a 19% quantum yield, and a biexponential 1.1/2.1 ns lifetime. The electronic environment for the cluster is controlled by the heteroatoms in the adenine and guanine. Most significantly, the N7 and the N2 in the guanine change the fluorescence quantum yield by 60-fold and shift the fluorescence lifetime by ∼3.8 ns. Thus, our studies discern distinct spectroscopic and structural roles for the nucleobase ligands in C4AC4TC3G, and these findings may help develop new DNA templates for other silver cluster adducts.

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Section: Discussionmentioning

confidence: 76%

A DNA-Encapsulated Silver Cluster and the Roles of Its Nucleobase Ligands

et al. 2018

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“…As a result, changes to the emission transition dipole on a faster time scale may be concealed or averaged out, especially if these changes are small, dim, or short-lived. To overcome this, we conducted polarized confocal microscopy on the C24-AgNC sample, in order to obtain spectral information along with polarization data at higher time resolution in order to investigate a potential correlation between the spectral fluctuations observed in a previous paper and orientation changes …”

Section: Results and Discussionmentioning

confidence: 99%

Probing the Absorption and Emission Transition Dipole Moment of DNA Stabilized Silver Nanoclusters

2017

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Using single molecule polarization measurements, we investigate the excitation and emission polarization characteristics of DNA stabilized silver nanoclusters (C24-AgNCs). Although small changes in the polarization generally accompany changes to the emission spectrum, the emission and excitation transition dipoles tend to be steady over time and aligned in a similar direction, when immobilized in PVA. The emission transition dipole patterns, observed for C24-AgNCs in defocused wide field imaging, match that of a single emitter. The small changes to the polarization and spectral shifting that were observed could be due to changes to the conformation of the AgNC or the DNA scaffold. Although less likely, an alternative explanation could be that several well aligned spectrally similar emitters are present within the DNA scaffold which, due to Förster resonance energy transfer (FRET) processes such as energy hopping, energy transfer, and singlet-singlet annihilation, behave as a single emitter. The reported results can provide more insight in the structural and photophysical properties of DNA-stabilized AgNCs.

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“…Using simple emission spectroscopy in isolation makes it very difficult to observe this effect, as emission peaks are only shied marginally from one another in these red-emitting cluster species. 26,36,37 Separation of Ag x (SG) Y mixture The use of high performance liquid chromatography has been instrumental in separating and characterizing metal clusters, including many different gold nanocluster species. 38 Herein, we have shown the utility of reverse-phase HPLC in separating these silver cluster species.…”

Section: Synthesis and Stabilitymentioning

confidence: 99%