Material Storage Mechanism in Porous Nanocarbon

Ajima, Kumiko; Yudasaka, Masako; Suenaga, Kazu; Kasuya, D.; Azami, Takeshi; Iijima, Sumio

doi:10.1002/adma.200306142

Cited by 85 publications

(97 citation statements)

References 17 publications

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“…[60]Fullerene quickly enters the internal space of oxNH580 through the holes (22,23), and we exploited this property of fullerene to show that the clusters form on most of the hole openings. Thus, oxNH580 was first treated with methanolic Gd(OAc) 3 , as described above, followed by a toluene solution of [60]fullerene: TEM observation of several of the dahlia aggregates (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The sample was sucked dry quickly by filtration paper and analyzed by TEM. Details of the method have been described (22,23).…”

Section: Treatment Of Gdoxnh580 With [60]mentioning

confidence: 99%

“…The NH is a conical tubule closed by caps and assembles radially into dahlia-like aggregates (see Figs. 1, 2, and 3, which is published as supporting information on the PNAS web site), which possess a number of end caps and structural defects on the side of the tubules, through which we can pierce holes by oxidation (21)(22)(23). This structural diversity permits us to simultaneously investigate the properties of a variety of hole structures for a single sample, an opportunity unavailable for the studies on structurally homogeneous NT samples.…”

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confidence: 99%

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Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn

Hashimoto

Yorimitsu

Ajima

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

104

105

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Selective synthesis of particles of angstrom to nanometer size consisting of one to many metal atoms is instrumental in various applications, but it has been hampered by the tendency of the metal atom to form large clusters. We found, as studied by the state-of-the-art electron microscopic technique, a strategy to produce metal-containing nanoparticles isolated from each other by depositing metal atoms in a hydrophilic hole on or in the interior of a carbon nanotube as demonstrated by the reaction of Gd(OAc) 3 with oxidized single-wall nanohorns. Besides the potential utilities of the deposited metal clusters, the metal deposition protocol provides a method to control permeation of molecules through such openings.carbon nanotube ͉ metal nanoparticle ͉ self-assembly ͉ metal deposition A s has been amply demonstrated in chemistry by way of metal-catalysis, metal-complexation should immensely widen the scope of carbon cluster science (1-5). Thus, metalcontaining hollow carbon clusters, such as endohedral metallofullerenes (6, 7) and carbon nanotube (NT) filled with metal atoms (3,4,(8)(9)(10)(11)(12), have been suggested as promising materials. However, the methodology to rationally control the size and the location of the metal clusters and to ensure high-yield production of the material on a large scale has been lacking. We report here a method for forming a one-to multiatom metal cluster specifically at the hydrophilic hole opening of a NT (8,13,14) as demonstrated by deposition of Gd(OAc) 3 in single-wall carbon nanohorns (NHs), a new variety of single-wall NTs (15). The hole-selective deposition of the Gd atoms allows atomic-scale detection of the structural defect in the graphitic materials, and, on a bulk scale, controls the permeability of molecules through the holes. The result would find use for modulation of the electronic properties of NTs (16).Attachment of one atom or a multiatomic cluster onto a selected location of the surface of materials is intellectually challenging and practically useful. Because the oxidized edge of NT is rich in hydrophilic functional groups, such as hydroxy and carboxyl groups (8,13,14,(17)(18)(19), and hence creates a ''locally amphiphilic'' structure (20) on a graphene sheet, we considered that selective accumulation of hydrophilic metal ions, one by one through self-assembly, onto a small hole of a partially oxidized graphene sheet should be possible. We report that treatment of single-wall NH possessing hole openings of several angstroms to Ϸ2-nm diameter with methanolic Gd(OAc) 3 ⅐(H 2 O) 4 permits selective deposition of one to several Gd(III) atoms in an opening at the tip of the tube, or a cluster of an average 1.6-nm diameter in the interior of an opening on the sidewall. The valence and the number of the deposited metal atoms were determined by high-resolution transmission electron microscopy (TEM) and quantitative electron energy-loss spectrometry (EELS) with atomic sensitivity in a dedicated scanning TEM (STEM) with 0.5-nm spatial resolution. With this analytical ...

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Section: Resultsmentioning

confidence: 99%

“…The sample was sucked dry quickly by filtration paper and analyzed by TEM. Details of the method have been described (22,23).…”

Section: Treatment Of Gdoxnh580 With [60]mentioning

confidence: 99%

mentioning

confidence: 99%

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Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn

Hashimoto

Yorimitsu

Ajima

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

104

105

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“…Thousands of SWNHox partially coalesce to form an 80-to 100-nm spherical aggregate (2), and this aggregate is expected to have enhanced permeability and retention properties (26,27) that make SWNHox effective for passive delivery of drugs to tumors. The holes of SWNHox observed with transmission electron microscopy (TEM) are 1-3 nm in diameter (28), and their pore sizes distributed in a range of 1-5 nm, showing a maximum at Ϸ2 nm (29), so that ZnPc [size: Ϸ1.4 nm (30)], similar to other molecules (7,8,(31)(32)(33), can pass into the SWNHox tubules. The edges of the SWNHox holes have many carboxyl groups that can be used to attach biological materials, such as proteins, to enhance the biocompatibility of SWNHox (34).…”

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confidence: 99%

Fabrication of ZnPc/protein nanohorns for double photodynamic and hyperthermic cancer phototherapy

Zhang

Murakami

Ajima

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

252

186

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Multifunctionalization of carbon nanotubules is easily achieved by attaching functional molecules that provide specific advantages for microscopic applications. We fabricated a double photodynamic therapy (PDT) and photohyperthermia (PHT) cancer phototherapy system that uses a single laser. Zinc phthalocyanine (ZnPc) was loaded onto single-wall carbon nanohorns with holes opened (SWNHox), and the protein bovine serum albumin (BSA) was attached to the carboxyl groups of SWNHox. In this system, ZnPc was the PDT agent, SWNHox was the PHT agent, and BSA enhanced biocompatibility. The double phototherapy effect was confirmed in vitro and in vivo. When ZnPc-SWNHox-BSA was injected into tumors that were subcutaneously transplanted into mice, the tumors almost disappeared upon 670-nm laser irradiation. In contrast, the tumors continued to grow when only ZnPc or SWNHox-BSA was injected. We conclude that carbon nanotubules may be a valuable new tool for use in cancer phototherapy.carbon nanotubules ͉ drug carrier ͉ drug delivery system ͉ nanoparticle ͉ photohyperthermia

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“…We have tested inserting or doping C60 molecules into nanocarbon materials, namely carbon nanohorns, which is similar to SCNTs. The doping was carried out in solution instead of conventional vapor phase that is not applicable to drugs [4]. We have confirmed that after oxidizing properly as-grown carbon nanohorns, we doped them with C60 and examined adsorption and release characteristics of them.…”

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confidence: 80%

The Role of Catalytic Nano-particles in Nano-Carbon Technology

Iijima

2005

MAM

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Single walled carbon nanotubes (SCNTs) are generated consistently in chemical vapor deposition method by using appropriate nano-sized metal particles as nucleation sites for the tubule growth.Under controlled conditions we have demonstrated that SCNTs can grow vertically on a silicon substrate with several millimeters height. A key factor here was to control precisely small amount of water in the reaction gas during the growth. The method is available for making patterned growth on a substrate. Some of our recent results will be presented with emphasis on providing the samples including fabricated ones upon request ( Fig. 1)[1].Traditionally, catalyst particles are examined with HRTEM and STEM with EELS spectroscopy. Platinum particles supported on carbon are one of key materials for the development of fuel cell electrodes. One of examples of HRTEM observation on Pt particles will be discussed [2]. Here we introduce the recent development of characterization of such particles in terms of energy filtered imaging of metal particles. They were placed at specially prepared surfaces of CNTs and also their hollow inside. The result demonstrates that our technique enables to image individual metal particles as small as a single atom. It will be emphasized here that the success is to use nano-spaces of single-walled nanotubes as supporting containers for metal particles. The tubes provide with noiseless film for TEM observations (Fig. 2) [3].Lastly, I will present the way to store nano-particles in the hollows of nanotubes. This study is aimed at developing a carrier for drug delivery systems. We have tested inserting or doping C60 molecules into nanocarbon materials, namely carbon nanohorns, which is similar to SCNTs. The doping was carried out in solution instead of conventional vapor phase that is not applicable to drugs [4]. We have confirmed that after oxidizing properly as-grown carbon nanohorns, we doped them with C60 and examined adsorption and release characteristics of them. The experiment has been applied to one of real drugs, Dexamethasone, and confirmed that the dopant drugs were stored inside the tubes and released under certain conditions [5].

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Material Storage Mechanism in Porous Nanocarbon

Cited by 85 publications

References 17 publications

Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn

Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn

Fabrication of ZnPc/protein nanohorns for double photodynamic and hyperthermic cancer phototherapy

The Role of Catalytic Nano-particles in Nano-Carbon Technology

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