Tailoring silver nanodots for intracellular staining

Choi, Sungmoon; Yu, Junhua; Patel, Sandeep; Tzeng, Yih-Ling; Dickson, Robert M.

doi:10.1039/c0pp00263a

Cited by 127 publications

(152 citation statements)

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“…and/or the surface-bound OH radicals, it can be regenerated by e CB -just after the h VB ? /OH radical transfer [38]. This HA-mediated null cycle should be favored at low pH conditions where its adsorption reaches a Effects of TiO 2 surface fluorination 137 maximum, and hindered at alkaline pH range where the adsorption is low, leading to faster PCD.…”

Section: Photocatalysis Of Humic Acidmentioning

confidence: 99%

“…MB was known to be degraded by surface-bound and/or surface-free OH radicals due to insignificant adsorption on the TiO 2 surface at circum-neutral pH [34][35][36], whereas HA was strongly adsorbed at the TiO 2 surface, thereby being degraded by the h VB ? and/or surface-bound OH radicals [37,38]. Surface fluorination of TiO 2 was found to have dual effects: it altered the adsorption behaviors of MB and HA, and enhanced OH radical-mediated oxidation.…”

Section: Introductionmentioning

confidence: 96%

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Effects of TiO2 surface fluorination on photocatalytic degradation of methylene blue and humic acid

2010

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Photocatalytic degradation (PCD) reactions of cationic methylene blue (MB) and anionic humic acid (HA) were studied in naked TiO 2 and fluorinated TiO 2 (F-TiO 2 ) suspensions in order to investigate how the modification of the TiO 2 surface functional group influenced PCD reactions. Adsorption behaviors of MB and HA in the naked TiO 2 followed a typical pH-dependent electrostatic interaction mechanism. On the other hand, those in the F-TiO 2 were markedly changed and even showed a reversed dependence in specific pH ranges due to surface fluoride interrupting the interaction of substrates and surface titanol groups. PCD rates of MB (k MB ) and its N-demethylation (Dk max ) were significantly increased by surface fluorination below circum-neutral pH range, in particular, by a factor of 12 and 54 at pH 2, respectively. In the case of HA, the fluorination had an insignificant effect on its degradation rate but appeared to change its degradation behavior. It has been suggested that, although the primary effect of fluorination enhances the photocatalytic production of hydroxyl radicals, the change in electrostatic interaction with substrates could affect PCD as well.

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Section: Photocatalysis Of Humic Acidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Effects of TiO2 surface fluorination on photocatalytic degradation of methylene blue and humic acid

2010

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“…Examples of some of the wide range of spectrally pure Ag cluster emitters that can be made changing buffer conditions and DNA sequences (From Ref. 39 - Reproduced by permission of The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC). Emission maxima (sequence) from left to right: 523 nm (C 20 ), 562 nm (AATTC 12 ), 590 nm (CGAAC 12 ), 615 nm (CGCGC 12 ), 635 nm (ATATC 8 ), 670 nm (GGGGC 8 ).…”

Section: Figurementioning

confidence: 99%

“…Red and green-emitting clusters are targeted to mitochondria and heparin sulfate (cell surface) within the same fixed cell by coupling different DNA sequences to the different antibodies. 39 …”

Section: Figurementioning

confidence: 99%

DNA-Templated Molecular Silver Fluorophores

Petty

Story

Hsiang

et al. 2013

J. Phys. Chem. Lett.

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134

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Conductive and plasmon-supporting noble metals exhibit an especially wide range of sizedependent properties, with discrete electronic levels, strong optical absorption, and efficient radiative relaxation dominating optical behavior at the ~10-atom cluster scale. In this Perspective, we describe the formation and stabilization of silver clusters using DNA templates and highlight the distinct spectroscopic and photophysical properties of the resulting hybrid fluorophores. Strong visible to near-IR emission from DNA-encapsulated silver clusters ranging in size from 5-11 atoms has been produced and characterized. Importantly, this strong Ag cluster fluorescence can be directly modulated and selectively recovered by optically controlling the dark state residence, even when faced with an overwhelming background. The strength and sequence sensitivity of the oligonucleotide-Ag interaction suggests strategies for fine tuning and stabilizing cluster-based emitters in a host of sensing and biolabeling applications that would benefit from brighter, more photostable, and quantifiable emitters in high background environments. KeywordsNoble metals; clusters; modulation; fluorescence; biolabel; imaging; photophysics Few-atom metal clusters exhibit distinctive, size-dependent behaviors along the transition from bulk to molecular scales. For example, as electron mean free path and Fermi screening length scales are approached, the excellent conductivity and optical reflectivity characterizing bulk metals morph into shape-dependent plasmon excitations, size-dependent redox potentials and chemical/biological reactivities, with discrete optical transitions emerging at even smaller sizes. [1][2][3][4] Resulting from their relative inertness and highly polarizable electronic transitions, molecular-scale noble metals have emerged as a promising class of fluorophores for materials and biological imaging. Characterized by excellent brightness and photostability, gold and silver clusters encapsulated by coordinating ligands feature strong optical transitions that vary not only with stoichiometry, charge, and geometry, but can also be strongly influenced by interactions with their encapsulating matrix. [5][6][7][8] As the molecular size scale is approached, few-atom metallic cluster sizes exhibit an insufficient density of states to close the "band gap" as occurs in bulk or nanoparticulate metals, leading to strong size-dependent optical and catalytic properties that in many cases are well-explained by the nuclear shell model for free electron energies and magic cluster sizes. [9][10][11] This approach has led to the extended atom description of metallic clusters and an effective expansion of the periodic table with size-dependent cluster behaviors when metalmetal interactions dominate cluster stability. 12, 13 * dickson@chemistry.gatech.edu. Although the protoplasmonic electronic structure of metal clusters is best observed in bare, unsolvated and isolated clusters, 9, 10, 14 ligands are essential to constrain growth, stabilize, an...

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“…47 Finally, 3 many AgNCs have relatively low photostability. 44,48,49 In this work, we take the advantage that AgNCs of different emission colors can be produced using different DNA sequences and prepared a total of eight AgNCs. We show that AgNCs have different sensitivity to Hg 2+ and different photostability.…”

Section: Introductionmentioning

confidence: 99%