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Nanographite structure/metal nanoparticle composite

外国特許コード F110005522
整理番号 N051-09WO
掲載日 2011年9月7日
出願国 アメリカ合衆国
出願番号 76758307
公報番号 20100029910
公報番号 8017729
出願日 平成19年6月25日(2007.6.25)
公報発行日 平成22年2月4日(2010.2.4)
公報発行日 平成23年9月13日(2011.9.13)
優先権データ
  • 特願2004-374093 (2004.12.24) JP
  • 2005JP023675 (2005.12.22) WO
発明の名称 (英語) Nanographite structure/metal nanoparticle composite
発明の概要(英語) The present invention makes it possible to efficiently recognize carbon nanotubes, carbon nanohorns or modifiers thereof and to support functional compounds by fusing the ability of ferritin molecules capable of forming nanoparticles of inorganic metal atoms or inorganic metal compounds.
In addition, because ferritin molecules are capable of forming two-dimensional crystals at the interface, the present invention makes it possible to align carbon nanotubes, carbon nanohorns with the use of the molecular arrangement ability of ferritin fused with nanographite structure recognition peptides.
A nanographite structure/metal nanoparticle composite is constructed, wherein a nanoparticle of an inorganic metal atom or an inorganic metal compound is retained in an interior space of a protein in which a nanographite structure recognition peptide is fused or chemically bound to a surface of a cage protein such as ferritin, and wherein a plurality of nanoparticles of an inorganic metal atom or an inorganic metal compound are supported on a nanographite structure with the use of affinity of the nanographite structure recognition peptide to the nanographite structure.
従来技術、競合技術の概要(英語) BACKGROUND OF THE INVENTION
Diamond and graphite, as crystal structures of carbon, have been well known in the field.
C60 was found in 1985 by R. E. Smalley, R. F. Curl and H. W. Kroto et al. (for example, Nature, 318: 162-163, 1985), and has a soccer ball-like structure comprising 12 pentagons and 20 hexagons.
In addition to C60, there are other large basket-like molecules such as C70 and C76.
This series of molecules is called "fullerene." Carbon compounds with structures that were previously unknown, such as "carbon nanotube" (Nature, 354: 56-58, 1991; Japanese Laid-Open Patent Application No. 2001-64004) and "carbon nanohorn" (Chem. Phys. Lett., 309: 165-170, 1999; Japanese Laid-Open Patent Application No. 2001-64004), were successively discovered by Sumio Iijima, in 1991 and 1999, respectively.
All of these fullerenes, carbon nanotubes and carbon nanohorns comprise six- and five-membered rings of carbon atoms, and form nanometer-scale fine structures; therefore, they have recently attracted a lot of attention as "nanographite structures".
There are many reasons that nanographite structures are of particular interest in the field.
For example, "carbon nanotubes can have both properties of metal and semiconductor due to the difference in their chirality" (Nature, 391: 59-62), and "metal-doped fullerene exhibits superconductivity" (Nature, 350: 600-601).
Furthermore, nanographite structures attract attention because of the "selective gas storage capability shown by carbon nanohorns" (Nikkei Science, 42, August issue, 2002), the "ability of carbon nanohorn for the support and sustained release of pharmaceutical compounds" (Japanese Patent Application No. 2004-139247; Mol Pharmaceutics 1: 399), and the like.
With the use of these characteristic properties, nanographite structures may be applied to new electrical materials, catalysts, optical materials, and other fields; in particular, they may be used for wiring of semiconductors, fluorescent indicator tubes, fuel cells, gas storage, vectors for gene therapy, cosmetics, drug delivery systems, biosensors, etc.
The present inventors and others have isolated a peptide motif which binds to a carbon nanohorn, one of nanographite structures, by the phage display technique (Japanese Laid-Open Patent Application No. 2004-121154; Langmuir, 20, 8939-8941, 2004).
On the other hand, ferritin proteins have been well known as a protein which stores "molecules of 'iron,' which is an essential metal and is toxic at the same time" in living bodies.
Ferritin exists universally, from animals and plants to bacteria, and is deeply involved in the homeostasis of iron element in living bodies or in cells.
Ferritin from higher eukaryotes such as human and horse forms a spherical shell structure consisting of a 24-mer approximately 12 nm in diameter, formed from peptide chains whose molecular weight is about 20 kDa, and has an interior space of 7 to 8 nm.
Ferritin stores iron molecules in this interior space as a mass of nanoparticulate iron oxide.
With regard to 24 subunits which constitute a protein spherical shell (cage), there are two types (type H and type L), and the ratio of these types varies depending on organism species and tissues.
Ferritin stores iron nanoparticles inside it under natural circumstances.
However, under artificial circumstances, it has been revealed that ferritin can store the substances in addition to iron such as oxides of beryllium, gallium, manganese, phosphorus, uranium, lead, cobalt, nickel, chromium, etc., and nanoparticles of semiconductors, magnets such as cadmium selenide, zinc sulfide, iron sulfide and cadmium sulfide.
Consequently, applied research of ferritin in the fields of material engineering of semiconductors and health care has been actively conducted.
If it is possible to combine nanographite structures having excellent properties with metal-filled ferritin molecules, the development of composite materials having an unprecedented new function can be expected.
In this case, a technique for making ferritin molecules efficiently recognize and bind to nanographite structures such as carbon nanotubes and carbon nanohorns, is required.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.

特許請求の範囲(英語) [claim1]
1. A nanographite structure/metal nanoparticle composite, comprising: (a) a nanographite structure selected from carbon nanotube and carbon nanohorn;
(b) ferritin containing within its interior space a nanoparticle of an inorganic metal atom or an inorganic metal compound; and
(c) a nanographite structure recognition peptide consisting of an amino acid sequence shown by DYFSSPYYEQLF (SEQ ID NO: 1) and that is fused to an N-terminal site of the ferritin;
wherein a plurality of the nanoparticles is supported on the nanographite structure through the affinity of the nanographite structure recognition peptide to the nanographite structure.
[claim2]
2. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the ferritin is higher eukaryote-derived ferritin.
[claim3]
3. The nanographite structure/metal nanoparticle composite according to claim 2, wherein the higher eukaryote-derived ferritin is horse spleen-derived type L ferritin.
[claim4]
4. A nanographite structure/metal nanoparticle composite, comprising: (a) a nanographite structure selected from carbon nanotube and carbon nanohorn;
(b) ferritin containing within its interior space a nanoparticle of an inorganic metal atom or an inorganic metal compound; and
(c) a nanographite structure recognition peptide consisting of an amino acid sequence shown by YDPFHII (SEQ ID NO: 2) and that is fused to an N-terminal site of the ferritin;
wherein a plurality of the nanoparticles is supported on the nanographite structure through the affinity of the nanographite structure recognition peptide to the nanographite structure.
[claim5]
5. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the nanoparticle is a metal nanoparticle.
[claim6]
6. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the nanoparticle is a metal compound nanoparticle.
[claim7]
7. The nanographite structure/metal nanoparticle composite according to claim 6, wherein the metal compound nanoparticle is a metal oxide nanoparticle.
[claim8]
8. The nanographite structure/metal nanoparticle composite according to claim 6, wherein the metal compound nanoparticle is a magnetic material nanoparticle.
[claim9]
9. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the metal is iron, beryllium, gallium, manganese, phosphorus, uranium, lead, cobalt, nickel, zinc, cadmium or chromium.
[claim10]
10. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the nanoparticle is a nanoparticle of iron oxide, a nanoparticle of cadmium selenide, a nanoparticle of zinc selenide, a nanoparticle of zinc sulfide, or a nanoparticle of cadmium sulfide.
[claim11]
11. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the carbon nanotube or the carbon nanohorn is constituted of a carbon structure to which a functional group is added.
[claim12]
12. The nanographite structure/metal nanoparticle composite according to claim 1, wherein the nanographite structure is two-dimensionally aligned on a substrate.
[claim13]
13. A method for adding and retaining a nanoparticle of an inorganic metal atom or an inorganic metal compound in an interior space of a ferritin in which a nanographite structure recognition peptide consisting of the amino acid sequence shown by DYFSSPYYEQLF (SEQ ID NO: 1) is fused to an N-terminal site of the ferritin; and supporting a plurality of the nanoparticles on a nanographite structure selected from carbon nanotube and a carbon nanohorn with the use of affinity of the nanographite structure recognition peptide to the nanographite structure.
[claim14]
14. A method for producing a composite of a nanographite structure selected from carbon nanotube and a carbon nanohorn, and nanoparticles of an inorganic metal compound, comprising the steps of: (i) adding and retaining a nanoparticle of an inorganic metal atom or an inorganic metal compound in an interior space of a ferritin in which a nanographite structure recognition peptide consisting of the amino acid sequence shown by DYFSSPYYEQLF (SEQ ID NO: 1) is fused to an N-terminal site of the ferritin;
(ii) supporting a plurality of nanoparticles of an inorganic metal atom or an inorganic metal compound on the nanographite structure with the use of affinity of the nanographite structure recognition peptide to the nanographite structure; and
(iii) removing the ferritin by a heat treatment.
[claim15]
15. A method for producing a composite of a nanographite structure selected from carbon nanotube and a carbon nanohorn and nanoparticles of an inorganic metal compound, comprising the steps of: (i) adding and retaining a nanoparticle of an inorganic metal atom or an inorganic metal compound in an interior space of a ferritin in which a nanographite structure recognition peptide consisting of the amino acid sequence shown by DYFSSPYYEQLF (SEQ ID NO: 1) is fused to an N-terminal site of the ferritin;
(ii) supporting a plurality of nanoparticles of an inorganic metal atom or an inorganic metal compound on the nanographite structure with the use of affinity of the nanographite structure recognition peptide to the nanographite structure; and
(iii) removing the ferritin by an electron beam treatment.
  • 発明者/出願人(英語)
  • SHIBA KIYOTAKA
  • SANO KENICHI
  • IWAHORI KENJI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
米国特許分類/主・副
  • 530/328
  • 530/326
  • 530/327
  • 530/329
  • 530/330
参考情報 (研究プロジェクト等) CREST Creation of Novel Nano-material/System Synthesized by Self-organization for Medical Use AREA
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