2001 Fiscal Year Final Research Report Summary
MRI contrast agents based on water-soluble Gd-metallofullere
| Project/Area Number |
12554026
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
機能・物性・材料
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| Research Institution | Nagoya University |
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Principal Investigator |
SHINOHARA Hisanori Nagoya University, Department of Chemistry Professor, 大学院・理学研究科, 教授 (50132725)
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| Co-Investigator(Kenkyū-buntansha) |
MIKAWA Masato Jaapan Schering Co.LTD., Head Resarch, 基礎研究部, 主任研究員
OKAZAKI Toshiya Nagoya University, Reserch Associate, 大学院・理学研究科, 助手 (90314054)
SUGAI Toshiki Nagoya University, Reserch Associate, 物質科学国際研究センター, 助手 (50262845)
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| Project Period (FY) |
2000 – 2001
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| Keywords | fullerenols / MRI / Contrast Agents / Gd / Relaxivity / water |
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| Research Abstract |
The relaxivities of each Gd-Merenols (pure ; Rl=62 mM-1 sec-1 , R2=69 mM-1 sec-1 , mixture ; Rl=56 rnM-1 sec-1, R2=67 mM-1 sec-1) were much higher than that of a commercial MRI contrast agent, MagnevistR (Rl=3.8 mM-1 sec-1, R2=4.3 mM-1 sec-1).
Gd-fullerenols showed high Rl throughout the range of magnetic fields. Further, the peak of Rl appeared nearby 1T. This field strength coincides with the range of common clinical MRI.
A Gd3+ ion with 7 unpaired electrons in half filled 4f orbital has been known to exhibit a strong relaxation capability of proton nuclear spin of nearby water molecules. The conventional MRI contrast agents consisting of the Gd3+ -chejate complexes have one direct coordination window to a water molecule that rapidly exchanges with the bulk water molecules surrounding the Gd3+ ion, which leads to an efficient nuclear spin relaxation of solvent water molecules. In contrast, in the Gd-fullerenols, there are no water molecules which can form a direct coordination to the encaged Gd3+ ion. Although the details of the electronic and magnetic properties of the current Gd-fullerenols is not known at present, it is probable that Gd@C82(OH)p has the paramagnetic property due to three electron transfer from Gd to the fullerene cage [ Gd3+@C82(OH)n3-] resulting in seven unpaired electrons in the Gd-4f orbitals inside the C82 cage and one on the cage.
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