2001 Fiscal Year Final Research Report Summary
Magnetic-field promotion in structures and functions of organized molecular membranes: Magnetic transportation of molecules and magnetofusion and magnetodivision of membranes
| Project/Area Number |
12640555
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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 |
機能・物性・材料
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| Research Institution | Shinshu University |
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Principal Investigator |
OZEKI Sutnio Shinshu University, Science, Chemistry, Professor, 理学部, 教授 (60152493)
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| Co-Investigator(Kenkyū-buntansha) |
IIYAMA Taku Shinshu University, Science, Chemistry, Assistant Professor, 理学部, 助手 (30313828)
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| Project Period (FY) |
2000 – 2001
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| Keywords | magnetic field / lipid / bimolecular membrane / black membrane / liposome / membrane potential / molecular transportation across a membrane / membrane fusion |
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| Research Abstract |
The membrane potential potential and resistance of a bimolecular membrane of lipids responded sensitively to steady magnetic fields. The largest changes occurred at around 0.15T, which corresponded to the smallest fixed charge density of the membrane. The response results in molecular orientation due to magnetic fields. When a lipid molecule tilts under a magnetic field, the occupied molecular area increases monotonically with a tilt angle and thus the charge density would also decrease monotonically with MF. On the other hand, with increasing the tilt angle, the hydrocarbon/water interface at the membrane surface should increase and destabilize the tilted structure: The critical tilt angle must exist. Then, one possible way to increase the charge density at higher MF than 0.15T would be to introduce membrane deformation in and out of a plain surface, which would lead to a reduction of the hydrocarbon/water interfacial energy and to relax the orientational defects ( among domains havin
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g diflerent orientation at a tilt angle ), respectively. Thus, the addition of magnetically anisotropic molecules to a membrane led to membrane potential regulation.
Deformation in membranes of dipalmitoylphosphatidylcholine ( DPPC ) led to the fusion of its liposome and large changes in the membrane potential of its black membrane under high magnetic fields of up to 28 T. The magneto fusion of DPPC liposomes significantly depended on the particle size and aromatic compounds doped. Although a theory for the magnetic deformation of liposomes predicts magneto fusion and magnetodivision, only magneto fusion was experimentally observed There seem to be two discrete liposome sizes stabilized at 10T, 160 and 430 nm in radius. The changes in liposome size due to magneto fusion gives an estimation of the local curvature of the membrane. The membrane potential of black DPPC membranes markedly increased with high magnetic fields and doped molecules corresponding to magnetofusion. Undulation of a membrane due to high magnetic fields may relax any orientational defects in a black lipid membrane, leading to a ripple-like structure, which may cause the magnetoresponse in the membrane potential. Less
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Research Products
(4 results)
