| Project/Area Number |
11650935
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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 |
高分子構造・物性(含繊維)
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| Research Institution | Waseda University |
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Principal Investigator |
KOMATSU Teruyuki Waseda University, Advanced Research Institute for Science and Engineering, Lecturer, 理工学総合研究センター, 講師 (30298187)
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| Co-Investigator(Kenkyū-buntansha) |
YANAGIMOTO Tetsuya Waseda University, Faculty of Science and Engineering, Research Associate, 理工学部, 助手 (70318781)
TSUCHIDA Eishun Waseda University, Faculty of Science and Engineering, Professor, 理工学部, 教授 (90063461)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Lipidporphyrin / Molecular Assembly / Porphyrin Molecular Fiber / Dioxygen Coordination / Phorpholipid Vesicle / Electronic Process / Photoreduction / LMCT Absorption / リピドポルフィリン鉄 / 自己組織化 / ポルフィリン分子繊維 / LMCT / ヒアルロン酸 / 過渡吸収スペクトル / 量子収率 / リピドポルフィリン |
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| Research Abstract |
In order to revive the dioxygen-coordination ability of the self-organized lipidporphyrinatoiron assemblies, two non-enzymatic systems to reduce the oxidized ferric metal centers have been constructed, and their mechanisms were studied.
First, a new lipidporphyrin with a covalently bound axial imidazole has been synthesized. It was self-organized in aqueous media to give fibrous aggregate (10 nm width). The AFM measurement in liquid phase revealed that four porphyrin molecules continuously aligned at the fiber's core, which can reversibly bind and release dioxygen under physiological conditions. The resonance Raman spectroscopy showed the coordination structure of the dioxygen, and the dioxygen-binding affinity and dioxygen association and dissociation rate constants were also measured.
Photoirradiation of phospholipid vesicle embedding lipidporphyrinatoiron(III) and lipidporphyrinato-zinc(II) (30-40 nmφ) induced electron transfer from the excited zinc(II) center to the Fe(III) complex. Under the coexistence of triethanolamine, the ratio of the ferrous complex increased and it can bind dioxygen.
On the other hand, saline solution of lipidporphyrinatoiron(III) showed a ligand-to-metal charge transfer (LMCT) absorption band at 362 nm. Under the presence of small amount of saccharides (hyaluronic acid, glucose, etc.), LMCT irradiation (365 nm) led to reduction of the central ferric iron(III), giving ferrous high-spin complex. This photoreduction involves fast intramolecular electron transfer, and the saccharide itself is oxidized to prevent the back electron transfer reaction. The result of the laser-flash photolysis showed that the formation of the ferrous high-spin complex occurred within 100 ns. The obtained Fe(II) complex formed a stable dioxygen adduct complex.
Furthermore, this photoreduction system could be applied to the albumin-porphyrinatoiron(III) hybrid, in which albumin played the role of the electron donner.
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