| Project/Area Number |
09558115
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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 |
Biomedical engineering/Biological material science
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
MARUYAMA Atsushi Assis.Prof., Dept.of Bio-molecular Engineering, TOKYO INSTITUTE OF TECHNOLOGY, 生命理工学部, 助手 (40190566)
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| Co-Investigator(Kenkyū-buntansha) |
AKAIKE Toshihiro Prof., Dept.of Biomolecular Engineering, TOKYO INSTITUTE OF TECHNOLOGY, 生命理工学部, 教授 (30101207)
MIWA Naoto Head of Basic Research Institute, Nihon Schering K.K., 基礎研究部(研究職), 部長
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | magnetic resonance imaging / contrast agent / polyion complex / pH response / gadolinium / tumor / 水素イオン濃度 / 環境応答性 / インテリジェントマテリアル / T1 緩和能 |
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| Research Abstract |
The purpose of this study was to establish a novel imaging concept which depict micro-environmental differences in pathological and/or physiological states between normal and damaged tissues. For the purpose we newly designed an intelligent contrast agent whose signal intensity is activated only at the lower pH.MRI contrast agents consisting of Gd ions shorten the T1 relaxation time of protons of its surrounding water molecules to enhance MRI signals. The signal enhancement activity of Gd ions is closely related with hydration behavior of the agent. Thus, one can modify the signal enhancement activity of Gd ions by regulating its hydration behavior. We employed polyion complex composed of a couple of weakly acidic and basic polymers to design pH-sensitive contrast agents. These oppositely charged polyions form stable polyion complex accompanying with release of water molecules when the charge in the complex is electrostatically equivalent. But it adsorbs water molecules when the charge balance is disordered by pH variation, In this study, pH-sensitive polyion complex containing Gd ions was prepared as an intelligent contrast agent and its pH-dependent enhancement in MRI signal was evaluated.
From the results of this study, this novel MRI contrast agent can specifically enhance MRI signal only at lower pH, even if it might be equally distributed. This reversible pH-dependent signal switching behavior of our newly designed MRI contrast agent will be an excellent tool for cancer diagnosis, since the extracellular fluid of tumor is more acidic than normal tissue and blood stream.
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