2007 Fiscal Year Final Research Report Summary
Development of Functional Liposomes Modified with Hydrophilic Porphyrins Based on Electrostatic Force
| Project/Area Number |
17550138
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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 |
Functional materials chemistry
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| Research Institution | Waseda University (2007)
Tokyo University of Science (2005-2006) |
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Principal Investigator |
OYAIZU Kenichi Waseda University, Department of Applied Chemistry, Associate Professor (90277822)
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| Project Period (FY) |
2005 – 2007
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| Keywords | porphyrin / liposome / electrostatic interaction / active oxygen species / catalyst / disproportionation / surface modification / nanoparticle |
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| Research Abstract |
The present study aimed at development of functionality of liposomes by surface modification with metal complexes using electrostatic interaction, thereby employing the functional liposomes to a variety of catalytic reactions that proceed at the surface of the liposome surface. Hydrophilic metal complexes such as cationic porphyrins substituted with pyridinium, sulfonium, and thophenium groups were synthesized. The metal complexes of these porphyrins with Fe and Mn were immobilized at the surface of the anionic liposomes by electrostatic interaction. The porphyrin complexes were exposed at the surface of the liposomes, in contrast to those reported for many types of porphyrin-bearing liposomes which typically employed hydrophobic complexes to accommodate the porphyrins in the lipid bilayers. The proposed porphyrin-modified liposomes proved to be a new type of functional nanoparticles. For example, the Fe-porphyrin modified liposome underwent catalytic disproportionation reaction of superoide anion radical according to 2O_2+2H^+→H_2O_2+O_2, and also catalyzed the Fenton reation of hydrogen peroxide according to H_2O_2→2OH・. The liposome was sufficientluy small in diameter to be delivered to cells, where it underwent the catalytic reaction related to the active oxygen species, producing the hydroxyl radical HO・to effectively induce apoptosis of the targeted cell. The porphyrin-modified liposome based on the electrostatic effect was shown to be an effective antitumor agent with high tumor cell selectivity.
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