| Project/Area Number |
17540382
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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 | Kyoto University |
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Principal Investigator |
SETO Hideki Kyoto University, Graduate School of Science, Associate Professor (60216546)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKAWA Kenichi Kyoto University, Graduate School of Science, Professor (80110823)
KITAHATA Hiroyuki Kyoto University, Graduate School of Science, Assistant Professor (20378532)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,810,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | amphiphilic membrane / lipid membrane / giant vesicle / unbinding transition / small-angle x-ray scattering / anomalous swelling / neutron spin echo / bending modulus / リン脂質 / 中性子スピンエコー / ラメラ-ラメラ相分離 / ベシクル / 静置水和法 / 時分割X線小角散乱 / AFM / 位相差顕微鏡 / unbinding転移 |
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| Research Abstract |
Biomembrane is mainly comprised of phospholipid molecules. Due to the amphiphilic property of phospholipid, these molecules assemble into bilayers in water to form vesicles. To investigate a model cell system, it is important to establish a method for creating giant vesicles (GVs) with a diameter above 1 micro-meter, which are comparable in size to living cells.
A natural swelling method, in which GVs are spontaneously formed by hydrating multi-stacked phospholipid dry film on a solid substrate, would be quite useful for creating a model cell because no physical or chemical stresses are applied to GVs. In this method, each lipid bilayer should peel off nom the stack of bilayers on a substrate and form a vesicle. Thus, we investigated the hydration process of multi-stacked phospholipid bilayers to form GVs by time-resolved small-angle X-ray scattering. The result indicated that the hydration proceeds in three stages. In the early stage, water molecules penetrate between lipid bilayers, and in the intermediate stage the lipid bilayers swell and reach a quasi-stable state. In the late stage, lipid bilayers gradually peel off from the stack. The kinetics of the peeling-off is discussed in terms of Kramers' broiling Only the outermost bilayers is unbound due to thermal fluctuations, and giant uni-lamellar vesicles will be formed.
Next, we investigated membrane fluctuations of lipid membranes by means of neutron spin echo spectroscopy. The hardening of a lipid bilayer upon approaching the main transition point in the anomalous swelling regime was observed, which naturally connects the bending modulus in the gel phase belog the main transition temperature.
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