Single molecules in soft matter : a study of biomolecular conformation, heterogeneity and plasmon enhanced fluorescence

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Single molecules in soft matter : a study of biomolecular conformation, heterogeneity and plasmon enhanced fluorescence

Title: Single molecules in soft matter : a study of biomolecular conformation, heterogeneity and plasmon enhanced fluorescence
Author: Yuan, Haifeng
Publisher: Molecular Nano Optics and Spins Group, Leiden Institute of Physics (LION), Faculty of Science, Leiden University
Issue Date: 2013-10-29
Keywords: Temperature cycle
Single molecules
FRET
Dynamical heterogeneity
Glass transition
Glass-forming liquids
Rotational diffusion
Gold nanorods
Plasmon-enhanced fluorescence
Nucleation
Abstract: We study the dynamics of single molecules and individual gold nanorods in glycerol at variable temperatures. We demonstrate temperature-cycle microscopy on FRET-labeled polyproline and double-stranded DNA molecules to access micro-second dynamics of single molecules, and reveal the influences of dye-dye interaction at short interdye distances on the observed FRET values. We use neutron-scattering techniques to examine the origin of solid-like structures suggested in previous reports and the influence of the thermal history. We find that crystal nucleation takes place in glycerol at temperatures very close to the glass transition temperature. This observation suggests that the thermal history of the glycerol sample needs to be controlled for studying dynamical heterogeneity in supercooled liquids. For the first time, we demonstrate gold nanorods as local viscosity reporter to study heterogeneity in supercooled liquids. Following rotational dynamics of individual gold nanorods in glycerol upon cooling below 226K, we start to observe deviations of local viscosity from the bulk viscosity of glycerol. Our observation suggests heterogeneity on relatively large length scale exists at surprisingly high temperatures. In the end, we demonstrate gold nanorods for enhancing fluorescence from single molecules and for fluorescence correlation spectroscopy at micromolar concentrations with single-molecule sensitivity.
Description: Promotor: M.A.G.J. Orrit
With Summary in Dutch
Faculty: Faculteit der Wiskunde en Natuurwetenschappen
Citation: Yuan, H., 2013, Doctoral Thesis, Leiden University
Series/Report no.: Casimir PhD Series;2013-23
ISBN: 9789085931645
Sponsor: ERC advanced grant "SiMoSoMa"
Handle: http://hdl.handle.net/1887/22072
 

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