Electron Transfer-Induced Blinking in Ag Nanodot Fluorescence

Patel, Sandeep; Cozzuol, Matteo; Hales, Joel M.; Richards, Christopher J.; Sartin, Matthew M.; Hsiang, Jung-Cheng; Vosch, Tom; Perry, Joseph W.; Dickson, Robert M.

doi:10.1021/jp9079537

Cited by 143 publications

(200 citation statements)

References 55 publications

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“…20,29,41,42 Longer-range, multi-base interactions are deduced from the sequence-encoded formation of spectrally-diverse clusters and from the base-dependence of the excited state dynamics. 16,17,19,26,43 Further perspective on the global DNA matrix is gained by pH coupling of the cluster emission and DNA folding in a conjugate that mimics an i-motif construct. 33 Two studies provide context for the central thesis of this work: the nucleobase environment for particular clusters can be redirected through base pairing.…”

Section: Discussionmentioning

confidence: 99%

Optical Sensing by Transforming Chromophoric Silver Clusters in DNA Nanoreactors

et al. 2011

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Bifunctional DNA oligonucleotides serve as templates for chromophoric silver clusters and as recognition sites for target DNA strands, and communication between these two components is the basis of an oligonucleotide sensor. Few-atom silver clusters exhibit distinct electronic spectra spanning the visible and near-infrared region, and they are selectively synthesized by varying the base sequence of the DNA template. In these studies, a 16-base cluster template is adjoined with a 12-base sequence complementary to the target analyte, and hybridization induces structural changes in the composite sensor that direct the conversion between two spectrally and stoichiometrically distinct clusters. Without its complement, the sensor strand selectively harbors ~7 silver atoms that absorb at 400 nm and that fold the DNA host. Upon association of the target with its recognition site, the sensor strand opens to expose the cluster template that has the binding site for ~11 silver atoms, and absorption at 720 nm with relatively strong emission develops in lieu of the violet absorption. Variations in the length and composition of the recognition site and the cluster template indicate that these types of dual component sensors provide a general platform for near infrared-based detection of oligonucleotides in challenging biological environments.

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Section: Discussionmentioning

confidence: 99%

Optical Sensing by Transforming Chromophoric Silver Clusters in DNA Nanoreactors

et al. 2011

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“…[ 11,47,48 ] This blinking process can be studied at the single molecule level by performing an autocorrelation analysis on the fl uorescence intensity trajectory. [ 49 ] Second order autocorrelation functions (ACF) were generated from the fl uorescence traces and most C24-AgNCs showed autocorrelation curves that could be fi tted with a two exponential model (The second, longer time component usually has a very small amplitude and was therefore not analyzed in detail).…”

Section: Single Molecule Measurements: Blinkingmentioning

confidence: 99%

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

Hooley

Paolucci

Liao

et al. 2015

Advanced Optical Materials

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In this paper, single molecule spectroscopy is used to probe the photophysical heterogeneity of near‐infrared emitting silver nanoclusters stabilized in single stranded DNA containing 24 cytosines (C24‐AgNCs). Focusing on this subset of emitters allows us to address and correlate their photophysical parameters. The results suggest that for these near‐infrared emitting C24‐AgNCs, the broad range of observed photophysical properties is due to the spectral heterogeneity of two species, one of which has a broad range of emission maxima and decay times. This conclusion is drawn by analyzing the results of a large number of single C24‐AgNCs where, for the first time, emission maxima, fluorescence decay times, fluorescence intensity, blinking, and photon antibunching are determined simultaneously. The single molecule measurements also reveal that some of the C24‐AgNCs can change their spectral properties during the measurement, while photon antibunching measurements verified that all the analyzed C24‐AgNCs behave as single emitters. While the overall spectral heterogeneity can be related to the immobilization in the polymer film and/or intrinsic heterogeneity of the C24‐AgNCs emitters, the exact origin of the dynamical changes has not been fully determined. However, changes in the AgNCs geometry, local environment, or changes in the DNA conformation are possible explanations.

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“…8,16 Third, weakly coupled dark states minimize intermittent fluorescence and thus increase net signal. 17,18 Furthermore, small steady state populations reside in these dark states and can be optically redirected to produce more emission. 19 Fourth, specific chromophores are encoded by the sequence of their DNA templates and are conveniently synthesized by reducing DNA-bound Ag + .…”

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confidence: 99%

A Silver Cluster–DNA Equilibrium

et al. 2013

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DNA encapsulates silver clusters, and these hybrid nanomaterials form molecular sensors. We discuss a silver cluster-oligonucleotide sensor with four characteristics. First, a specific reporting cluster forms within a single-stranded DNA. This template uses the 5’ cluster domain CCCCAACTCCTT with different 3’ recognition sites for complementary oligonucleotides. The modular composite strand exclusively forms a cluster with λmax = 400 nm and with low emission. Conjugates were chromatographically purified, and their elemental analysis measured a cluster adduct with ~11 silver atoms. Second, hybridization transforms the cluster. Size exclusion chromatography shows that the 3’ recognition sites of the single-stranded conjugates hybridize with their complements. This secondary structural change both shifts cluster absorption from 400 to 490 nm and develops emission at 550 nm. Third, cluster size remains intact. Like their violet predecessors, purified blue-green clusters have ~11 silver atoms. Cluster integrity is further supported by extracting the complement from the blue-green conjugate and reversing the spectral changes. Fourth, the cluster transformation is an equilibrium. Complementary strands generate an isosbestic point and thus directly link single-stranded hosts for the violet cluster and their hybridized analogs for the blue-green cluster. This equilibrium shifts with temperature. A van’t Hoff analysis shows that longer and more stable duplexes favor the blue-green cluster. However, hybridized cluster hosts are less stable than their native DNA counterparts, and stability further degrades when short complements expose nucleobases within S1-S2. Duplex instability suggests that unpaired nucleobases coordinate the violet cluster and favor the single-stranded sensor. A balance between innate hybridization and exogenous folding highlights a distinct feature of silver clusters for sensing – they are both chromophoric reporters and ligands that modulate analyte-sensor interactions.

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Electron Transfer-Induced Blinking in Ag Nanodot Fluorescence

Cited by 143 publications

References 55 publications

Optical Sensing by Transforming Chromophoric Silver Clusters in DNA Nanoreactors

Optical Sensing by Transforming Chromophoric Silver Clusters in DNA Nanoreactors

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

A Silver Cluster–DNA Equilibrium

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