| POLYMERS Vol.60 No.2 |
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COVER STORY
Single-Molecule Spectroscopy: A New Window to the Nanoworld of Polymers |
| COVER STORY: Highlight Reviews |
| Nanoscale Dynamics of 3D Network Formation in Polymeric Materials: Evaluation by Tracking Individual Motions of Guest Dyes | Syoji ITO and Hiroshi MIYASAKA |
| <Abstract> Network
formation in polymer materials drastically affects their various properties.
In the present article, we focus on recent investigations of thermal
/ photo-induced crosslinking processes in polymer systems by means of
wide-field single-molecule fluorescence imaging (WF-SMI) and tracking
(SMT). Translational and rotational motions of individual guest molecules,
obtained by SMT with ca. 10-nm spatial resolution, directly provide information
on the time evolution of the network formation accompanied with the spatial
heterogeneity and temporal hierarchy in molecular motions; e.g., for
the crosslinking in a thermo-curable poly(2-hydroxyethylacrylate) based
material, it was revealed that the translational diffusion of guest molecules
was inhibited at the early stage of the crosslinking while keeping the
rotational diffusion still active, the fraction of translationally immobilized
dyes increased with increasing number of crosslinking points, and at
the last stage both the translational and rotational motions stopped.
By introducing several experimental results, we discussed the advantage
of single molecule detections in these investigations. Keywords: Single Molecule Tracking / Network Formation / Crosslinking / Fluorescence Detection |
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| Structural Conformation and Photophysical Properties of Conjugated Polymer Molecules | Satoshi HABUCHI and Martin VACHA |
| <Abstract> Conjugated
polymers are an important class of materials for optoelectronic applications.
Due to their conformational diversity, intrinsic photophysical properties
of these molecules are hidden in the ensemble average. In this review
article, we introduce single-molecule microscopy research which reveal
static and dynamic disorder of conjugated polymers. Especially, we focus
on relationship between structural conformation and photophysical properties
of individual conjugated polymer molecules. Keywords: Conjugated Polymer / Single Molecule / Fluorescence Microscopy / Conformatioin / Exciton Migration / 3 Dimensional Anisotropy / Super Resolution Microscopy |
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| Learning Glass Transition Using Single-Molecule Fluorescence Spectroscopy | Hiroshi UJI-I |
| <Abstract> Polymer
relaxation dynamics are complex processes. While polymers look homogeneous,
they are in fact temporally and spatially heterogeneous at molecular
level. Single-molecule spectroscopy (SMS) is an ideal tool to address
such heterogeneity. This contribution will introduce the use of SMS to
study the relaxation dynamics of polymers near the glass temperature. Keywords: Polymer / Glass Temperature / Glass Transition / Glass Temperature / Single-Molecule / Defocused Imaging |
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| Structural Analysis of an Individual Polymer Chain by Single Molecule Detection | Hiroyuki AOKI |
| <Abstract> The
real-space observation of the conformation of a single polymer chain
would provide us with the indispensable information to understand the
structure and dynamics of polymer materials. The development of novel
optical imaging methods overcomes the diffraction barrier and it enables
the direct observation of individual chains. This paper describes the
principle of the recent high resolution optical microscopy and its application
in the structural analysis of polymer systems. Keywords: Single Molecule / Single Polymer Chain / Conformation / Fluorescence / Super-Resolution Technique / Near-Field Optical Microscopy |
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| Conformational Change Dynamics of DNA and Protein Studied by Single-Molecule Fluorescence Spectroscopy | Jungkweon CHOI and Tetsuro MAJIMA |
| <Abstract> In
order to understand the unique features of biomolecules such as DNA and
a protein, it is important to exactly elucidate their conformational
changes and dynamics occurring under physiological conditions. Recent
advances in optical imaging and biomechanical techniques offer opportunities
to observe the dynamic behavior of a single biomolecule and to determine
reaction mechanisms at the single-molecule level. Moreover it enables
us to investigate the heterogeneity in the reaction mechanisms observed
between the single-molecule level and in the bulk phase. In this review,
we provide a brief introduction to the single-molecule fluorescence spectroscopy. Keywords: Single-Molecule Fluorescence Spectroscopy / Conformational Change Dynamics / DNA / Charge Transfer / Protein Folding / Protein-Protein Interaction |
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| COVER STORY:Topics and Products |
| A Single-Molecule Photoswitch Using Fluorescent Photochromic Molecules | Tsuyoshi FUKAMINATO and Masahiro IRIE |
| <Abstract> Fluorescent
photochromic molecules, which have both photochromic and fluorescent
chromophores in a molecule, have attracted increasing interest because
of their potential applications to optical memories, molecular switches,
fluorescent biological markers and super-high resolution fluorescence
imaging. Here, we report on the progress of our research to detect and
analyze the fluorescent photoswitching at a single-molecule level. Keywords: Photochromism / Diarylethene / Fluorescence / Photoswitching |
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| Elucidation of the Primary Events of Cell Signaling Favored by Quantum-Dot Single Molecule Imaging | Mitsuru ISHIKAWA and Vasudevanpillai BIJU |
| <Abstract> Here
we highlight a recent achievement of revealing association of two EGF-EGFR
to form (EGF-EGFR)2 and dissociation of (EGF-EGFR)2 into each EGF-EGFR
in a reversible manner. This observation is favoured by the use of quantum
dot labeling persistent against photobleaching, shedding light on the
cell signaling mechanism activated by (EGF-EGFR)2. Keywords: EGFR / EGF / Fluorescence / Single Molecule / Quantum Dot |
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| Single-Photon Emission Behavior form Single Conjugated Polymer Chains | Sadahiro MASUO |
| <Abstract> The
relationship of molecular weight (MW) and chain conformation to single-photon
emission from single conjugated polymer chains was investigated. We demonstrated
that the probability of single-photon emission increased with decrease
in the spatial size of the polymer chain. Keywords: Conjugated Polymer / Single-Photon / Antibunching / Single Molecule |
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| Single-Molecule Spectroscopy of a Structural Change of a Protein | Hiroyuki OIKAWA, Satoru FUJIYOSHI, Takehisa
DEWA, Mamoru NANGO, and Michio MATSUSHITA |
| <Abstract> Temperature
dependence between 5 and 18 K of the spectral jump of individual B800
pigments in a light-harvesting 2 complex, revealed structural change
of the complex occurring at a rate independent of temperature. The process
is ascribed to tunneling of a proton of hydrogen bond at the pigment
binding site. Keywords: Single-Molecule Spectroscopy / Spectral Jump / Proton Tunneling / Hydrogen Bond / Binding Site / Light-Harvesting 2 Complex |
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| Growing Polymers: A Personal Account |
| Ethos Fosters Serendipity | Takayuki KUROKAWA |
| <Abstract> In order to foster serendipity of students, what can professors do? |
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| Load to Educator | Tsuyohiko FUJIGAYA |
| <Abstract> I was dreaming to bring up young students since I was a student. And, luckily, 10-years’ training led to my dream at the west end of Japan. The story is about the precious meetings with my seniors and small stories about my works. |
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| Front-Line Polymer Science |
| Simulation for Dynamics of Polymers | Yuichi MASUBUCHI |
| <Abstract> A
review on the state-of-the-art in simulation of polymer dynamics is given,
with the particular focus on coarse-graining techniques, rare-event simulations,
multi-scale simulations and special purpose hardwares. The number of
publications on polymer simulations has been being constantly increasing
reflecting the progress in the modeling and the computational technology.
Indeed, the coarse-graining is essential for polymer simulations for
the reduction of calculation costs. Further, as a recent development
the coexistence of particles with different level of coarse-graining
has been realized. The modeling for rare-event simulations has also been
developed for some problems, which cannot be dealt with the coarse-graining
techniques. In combination with the coarse-graining, the multi-scale
simulation (which utilizes couples of simulations in different descriptions
of the system) is another key concept to cover the broad temporal and
spatial range of the problems in polymer science. The use of special
hardware such as GPU is a new trend in computational technology and is
being imported to polymer simulations. Keywords: Polymer Dynamics / Simulations / Coarse-Graining / Multi-Scale Simulations |
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| Copyright(C) 2011 The Society of Polymer Science, Japan All Rights Reserved. |