2005 Fiscal Year Final Research Report Summary
Dielectric spectroscopy and SAXS investigations on self-organization mechanism of biologically-originated systems
| Project/Area Number |
16540372
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics/Chemical physics
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| Research Institution | Waseda University |
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Principal Investigator |
SATO Takaaki Waseda University, Faculty of Science and Engineering, Lecturer, 理工学術院, 講師 (20373029)
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| Project Period (FY) |
2004 – 2005
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| Keywords | dielectric spectroscopy / small angle scattering (SAXS) / amphiphilic polymer / hydrogen-bond liquid / protein / hydration / micelle / structure factor |
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| Research Abstract |
The main goal of this study is to clarify self-organization mechanisms of biologically-originated amphiphilic polymers in water, where an interplay between static structures, such as particle structure and interparticle interaction potential, and dynamical aspects like high-frequency dynamics of solvents and hydration behavior has been scrutinized by elaborately combined spectroscopic and scattering techniques, e.g., dielectric spectroscopy and small-angle X-ray scattering (SAXS).
A general rule that can consistently explain relation between dielectric and Raman spectra of hydrogen-bond liquids has been for the first time elucidated ; the collective relaxation process, i.e., the main contribution to the dielectric spectrum specific to hydrogen-bond liquids involving a long range dipole-dipole interaction, is virtually not Raman active. The results will lay the foundation for complete understanding microscopic-macroscopic correlation in hydrogen-bond liquid dynamics.
We have examined stat
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ic structures and molecular dynamics of a nano-assembly (in particular, a micelle) that is formed by biologically-originated as well as synthetic amphihilie in water. We have found that an accurate static structure factor analysis by GIFT (generalized indirect Fourier transformation) technique combined with dynamic hydration number analysis by dielectric spectroscopy can quantitatively explain the effects of hydrated water on excluded volume of micelles and its contribution to isothermal compressibility of the system. Our SAXS and rheology data clearly demonstrate that phase behavior of sugar-based surfactant microemulsions are closely linked with elongation of a micelle into rodlike or wormlike ones due to free-energy optimization.
Furthermore, we have attempted to construct a new approach to the calculation of the radial distribution functions (RDFs) and/or pair correlation functions from experimental static structure factor, introducing the so-called SQ-IFT (structure factor indirect Fourier transformation) method, and confirmed its versatile applicability. To calculate the RDFs of molecular liquids from liquid diffraction data, a conventionally utilized scattering vector-weighted structure function is no longer required. Simultaneously, SQ-IFT can provide potential model-free real space information on protein-protein spatial correlations in solution. Less
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