Origins of Nonexponential Decay in Single Molecule Measurements of Rotational Dynamics

Wei, Chia-Yin Joyce; Kim, Yeon Ho; Darst, Richard K.; Rossky, Peter J.; Bout, David A. Vanden

doi:10.1103/physrevlett.95.173001

Cited by 55 publications

(82 citation statements)

References 14 publications

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“…As for the ensemble, we fitted a single exponential to the autocorrelation function C A Ј(t) of the lineardichroism time trace to obtain the tumbling time in the given † A possible source of nonexponentiality is the nonspherical shape of the molecule. Wei et al (35) have shown that the associated high-order contributions to the correlation function are much reduced by collection over a finite solid angle and are therefore negligible in practice.…”

Section: Methodsmentioning

confidence: 99%

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules

Zondervan

Kulzer

Berkhout

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

147

180

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We probe the rotational diffusion of a perylene dye in supercooled glycerol, 5-25 K above the glass-transition temperature (T g ‫؍‬ 190 K) at the ensemble and the single-molecule level. The singlemolecule results point to a broad distribution of local viscosities that vary by a factor of five or more for different individual fluorophores at a given temperature. By following the same single molecules at various temperatures, we find that the distribution of local viscosities itself broadens upon approaching T g. This spatial heterogeneity is found to relax extremely slowly, persisting over hours or even days. These results convey a picture of heterogeneous liquid pockets separated by solid-like walls, which exist already well above the viscosimetric glass transition.fluorescence ͉ glass transition ͉ anisotropy ͉ correlation G lycerol is an archetypal molecular glass former. Although glycerol crystals can be grown from solution, the pure liquid readily supercools because of its high viscosity [10 3 times that of water at room temperature (1)], which is caused by the formation of a highly branched network of intermolecular hydrogen bonds. The viscosity of supercooled glycerol increases by 10 orders of magnitude between 291.8 K, the melting temperature of crystalline glycerol, and its viscosimetric glass-transition temperature T g ϭ 190 K. Throughout this range of temperatures, macroscopic rheology measurements seem consistent with the expected behavior of a Newtonian liquid, although they also reveal highly nonexponential kinetics (1-3).The necessity for cooperative motion at larger and larger scales on approaching the glass transition was recognized a long time ago by Adam and Gibbs (4). In their view, glass formation arises from dynamical arrest of cooperative domains, and their spread in sizes leads to an overall nonexponential relaxation. Indeed, spatially inhomogeneous dynamics (5) have been observed with a variety of techniques in many glass formers, including simple liquids (6-10) and polymers (11-15). Inhomogeneities have been found in the particular case of supercooled glycerol by dielectric hole burning (16), NMR (17), x-ray (18), light scattering (19), and stimulated Brillouin gain spectroscopy experiments (20, 21). These observations have to be reconciled with the common view of a supercooled liquid, which is supposed to remain a normal ergodic liquid until the glass transition. Heterogeneous regions with different relaxation dynamics are therefore expected to exchange with one another to restore ergodicity, by processes called environmental exchanges (6,9,10,12,(14)(15)(16). The typical mechanisms, length scales, and time scales of environmental exchanges remain largely unclear. NMR and dielectric relaxation point to times comparable to the molecular rotation times (16,22), whereas light scattering and fluorescence show inhomogeneities with exceedingly slow relaxation (9,12,(19)(20)(21).Single-molecule fluorescence is a well established method for studying rotational diffusion (23-26). Linear dichroism...

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Section: Methodsmentioning

confidence: 99%

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules

Zondervan

Kulzer

Berkhout

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

147

180

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“…[54][55] Fisz et al 54 and Wei et al 55 have discussed a detailed procedure for taking in account of this. However, for the sake of simplicity, we have used equation (1) as an approximation.…”

Section: Picosecond Time-resolved Fluorescence Decays Under a Micrmentioning

confidence: 98%

Intermittent Fluorescence Oscillations in Lipid Droplets in a Live Normal and Lung Cancer Cell: Time-Resolved Confocal Microscopy

2015

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Intermittent structural oscillation in the lipid droplets of live lung cells is monitored using time-resolved confocal microscopy. Significant differences are observed between the lung cancer cell (A549) and normal (nonmalignant) lung cell (WI38). For this study, the lipid droplets are covalently labeled with a fluorescent dye, coumarin maleimide (7-diethylamino-3-(4-maleimido-phenyl)-4-methylcoumarin, CPM). The number of lipid droplets in the cancer cell is found to be ∼20-fold higher than that in the normal (nonmalignant) cell. The fluctuation in the fluorescence intensity of the dye (CPM) is attributed to the red-ox processes and periodic formation/rupture of the S-CPM bond. The amount of reactive oxygen species (ROS) is much higher in a cancer cell. This is manifested in faster oscillations (0.9 ± 0.3 s) in cancer cells compared to that in the normal cells (2.8 ± 0.7 s). Solvation dynamics in the lipid droplets of cancer cells is slower compared to that in the normal cell.

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“…For a number of years, researchers have attempted to monitor relaxation processes in glass formers by embedding a single dye molecule in a polymer of interest. [90][91][92][93][94][95] The idea is that small rotational motions of the embedded dye would be able to report back on the relaxation process of the polymer under investigation. Several microscopy techniques have been developed over the last years to monitor the rotational motion of single molecules in three dimensions.…”

Section: Following Polymer Dynamics Near the Glass-transitionmentioning

confidence: 99%

The Rylene Colorant Family—Tailored Nanoemitters for Photonics Research and Applications

et al. 2010

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This Review summarizes the latest advances in the field of rylene dyes and rylene nanoemitters for applications in photonics, and describes the influence of the dye design on the optical properties, the self-assembly, the molecular interactions, as well as the labeling specificity of the compounds. The interplay between tailored (macro)molecular design and bulk/single-molecule spectroscopy enables complex processes to be explained, for example, the kinetics of energy-transfer processes or (bio)catalysis. Such investigations are essential for the ultimate design of optimized nanoemitters, and require a close cooperation between spectroscopists and preparative organic chemists.

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Origins of Nonexponential Decay in Single Molecule Measurements of Rotational Dynamics

Cited by 55 publications

References 14 publications

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules

Intermittent Fluorescence Oscillations in Lipid Droplets in a Live Normal and Lung Cancer Cell: Time-Resolved Confocal Microscopy

The Rylene Colorant Family—Tailored Nanoemitters for Photonics Research and Applications

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Origins of Nonexponential Decay in Single Molecule Measurements of Rotational Dynamics

Cited by 55 publications

References 14 publications

Local viscosity of supercooled glycerol near T g probed by rotational diffusion of ensembles and single dye molecules

Local viscosity of supercooled glycerol near T g probed by rotational diffusion of ensembles and single dye molecules

Intermittent Fluorescence Oscillations in Lipid Droplets in a Live Normal and Lung Cancer Cell: Time-Resolved Confocal Microscopy

The Rylene Colorant Family—Tailored Nanoemitters for Photonics Research and Applications

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Product

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About

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules

Local viscosity of supercooled glycerol near T _g probed by rotational diffusion of ensembles and single dye molecules