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ABSTRACT: Carbon nanotubules, such as nanotubes and nanohorns, are potentially useful as drug delivery or hyperthermia agents for cancer therapy. However, the biokinetics of variously sized nanocarbons are important for their medical application and risk assessment. To examine the time course of the biodistribution of carbon nanohorns (CNHs) in mice, CNH aggregates of 100 nm (L-CNHs) or CNHs of 30-50 nm (S-CNHs) were dispersed with lipid polyethylene glycol and administered to mice through tail vein injection. Histological observation revealed that S-CNHs accumulated more slowly than L-CNHs in the liver and spleen. The accumulation of L- and S-CNHs in spleen reached saturation within 1 and 48 hours, respectively, and the accumulation in liver reached saturation within 48 hours and >7 days, respectively. CNHs did not accumulate appreciably in lung, skin, or kidney. Histologic, hematologic, and immunologic (IL-6, TNF-α, and IFN-γ) tests did not reveal obvious toxicologic lesions at any time point.
Nanomedicine: nanotechnology, biology, and medicine 01/2013; · 5.44 Impact Factor
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ABSTRACT: For applications in standard optical devices, single-wall carbon nanotubes (SWCNTs) exhibiting emissions near 1500 nm are potentially feasible because silicon semiconductors efficiently transmit the light in this region. However, techniques to extract such semiconducting SWCNTs have not been reported thus far. In this study, using poly(9,9-dioctylfluorene-alt-pyridine) (PFOPy) as a dispersant in organic solvent, we succeeded in selectively dispersing SWCNTs which show near-infrared fluorescence around 1500 nm. On the basis of optical absorption and photoluminescence excitation spectroscopy, we revealed that the outstanding tube-structure preference of PFOPy can be interpreted by a characteristic "wavy" conformation of PFOPy on the tube wall.
ACS Applied Materials & Interfaces 12/2012; · 4.53 Impact Factor
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ABSTRACT: Amphiphilic lipid-poly(ethylene glycol) (LPEG) is widely used for the noncovalent functionalization of graphene nanomaterials (GNMs) to improve their dispersion in aqueous solutions for biomedical applications. However, not much is known about the detachment of LPEGs from GNMs and macrophage uptake of dispersed GNMs in relation to the alkyl chain coverage, the PEG coverage, and the linker group in LPEGs. In this study we examined these relationships using single walled carbon nanohorns (SWCNHs). The high coverage of PEG rather than that of alkyl chains was dominant in suppressing the detachment of LPEGs from SWCNHs in protein-containing physiological solution. Correspondingly, the quantity of LPEG-covered SWCNHs (LPEG-SWCNHs) taken up by macrophages decreased at a high PEG coverage. Our study also demonstrated an effect of the ionic group in LPEG on SWCNH uptake into macrophages. A phosphate anionic group in the LPEG induced lower alkyl chain coverage and easy detachment of the LPEG, however, the negative surface charge of LPEG-SWCNHs reduced the uptake of SWCNHs by macrophages.
Acta biomaterialia 09/2012; · 3.98 Impact Factor
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ABSTRACT: Identification of individual atoms and examination of their electronic properties in materials are the ultimate goal of all microscopy-based analytical techniques. Here, we demonstrate successful single-atom imaging and spectroscopy in low-dimensional materials using (scanning) transmission electron microscopy together with electron energy-loss spectroscopy (EELS). Edges and point defects in single-layered materials such as graphene, hexagonal boron nitride and WS(2) nanoribbons are investigated by annular dark-field imaging and EELS fine-structure analysis. Individual dopant atoms are unambiguously identified in nano-peapods. It is noteworthy that irradiation damage and specimen contamination even at the single-atom level are crucial issues in these experiments.
Journal of electron microscopy 07/2012; 61(5):285-91. · 1.31 Impact Factor
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ABSTRACT: Carbon nanotubes perform well in preclinical tests for drug delivery and diagnostic imaging, but controlling the size at less than 100 nm to avoid nonspecific uptake by reticuloendothelial systems while targeting delivery to cells of interest via receptor-mediated endocytosis is difficult, which currently limits their widespread use. Herein, 20-50-nm graphene tubules, small-sized single-walled carbon nanohorns (S-SWNHs), are obtained with a yield of 20% or higher by an oxidative exfoliation of 100 nm pristine SWNH aggregates. S-SWNHs are highly hydrophilic and remarkably resistant to cellular uptake by macrophages (RAW 264.7 cells), tumor cells (HeLa or KB), or normal cells (FHs 173We). The nonstimulatory property to cell membranes therefore makes cellular uptake control of S-SWNHs by functionalization easy. By attaching phospholipid polyethylene glycol, the cellular internalization of S-SWNHs is almost completely inhibited in RAW 264.7 macrophages. When functionalized with tumor-targeting folic acid (FA), FA-S-SWNHs are taken up by FA receptor-overexpressing KB cells but not by normal human embryonic cells (FHs 173We), which do not express the FA receptor. With a high rate of stealth and targeting in vitro, S-SWNHs are one of the most promising nanoparticles for medical use.
Small 06/2012; 8(16):2524-31. · 8.35 Impact Factor
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ABSTRACT: It has been reported that single wall carbon nanohorns (SWCNHs) with holes opened by slow air oxidation have few carbonaceous
dusts inside nanohorns, which is advantageous for storing materials inside the inner nanospaces of SWCNHs. However, the number
of carboxyl groups of air-oxidized SWCNHs is small, which is disadvantageous for chemical functionalization. We show in this
report that the double oxidation, namely the slow air-oxidation followed by treatment with hydrogen peroxide at room temperature
for 4 days successfully formed the holes in walls of SWCNHs without few carbonaceous dusts and with many carboxyl groups.
Applied Physics A 04/2012; 100(2):379-383. · 1.63 Impact Factor
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ABSTRACT: Aiming at improving the dispersion state of single wall carbon nanohorns (SWNHs) in highly salted aqueous environment for
potential biological applications, we compared the dispersion ability of different PEG-based dispersants in this work. We
have found that ceramide-conjugated poly(ethylene glycol) (CPEG) dispersed SWNHs better than phospholipid-conjugated PEG (DPEG)
in both water and phosphate buffer saline (PBS), which was evidenced by the measurements of particle sizes and dispersion
stability. The large zeta potentials, according to the high surface charges, did not fully explain the high dispersion ability
of CPEG for SWNHs. We propose that the more neutral linker group between alkyl and PEG chains in CPEG, in contrast to the
charged phosphoethanolamino group in DPEG, resulted in the larger number of CPEG molecules attaching on SWNHs, and those PEG
molecules enhanced the dispersion of SWNHs in water and PBS. In addition, for the first time we reported the adverse effect
of the amino terminal group of PEG chain on the dispersion ability, compared with the methyl terminal group.
Applied Physics A 04/2012; 99(1):15-21. · 1.63 Impact Factor
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ABSTRACT: The stability of open edged multi-walled carbon nanotubes has been investigated by using in situ high resolution transmission
electron microscopy at elevated temperatures. Formation of inter-shell structures was experimentally observed for the first
time and attributed to a robust interaction between adjacent concentric shells (so-called lip-lip interaction). The fl uctuating
behavior of the inter-shell structures suggests a mechanism by which the carbon atoms can pass in or out through the inter-shell
edges during carbon nanotube growth or shrinkage processes.
KeywordsMulti-walled carbon nanotubes-lip-lip interaction-in situ transmission electron microscopy
Nano Research 04/2012; 1(5):434-439. · 6.97 Impact Factor
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ABSTRACT: Cellular responses to graphene-based, nanometer-sized materials, such as carbon nanotubes and single-walled carbon nanohorns (SWNHs), have previously been studied at low-uptake levels. Here, by exploiting the availability of large quantities of SWNHs, cytotoxicity and the immunological responses induced by the abundant uptake of these structures were studied in RAW 264.7 murine macrophages. As much as half the cell interior was pigmented black by SWNHs, which were preferentially localized to lysosomes. High-uptake was shown to destabilize lysosomal membranes and generate reactive oxygen species that resulted in apoptotic, as well as necrotic, cell death. Despite these dramatic responses, only low levels of cytokines were released. The results will be interesting for future studies of the nanocarbon toxicity mechanisms and for medical applications of nanocarbons, especially those relying on lysosomes as target organelles for drug delivery or imaging.
Biomaterials 12/2011; 33(9):2762-9. · 7.40 Impact Factor
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ABSTRACT: Prednisolone (PSL), an anti-inflammatory glucocorticoid drug, was adsorbed on oxidized single-walled carbon nanohorns (oxSWNHs) in ethanol-water solvent. The quantity of adsorbed PSL on the oxSWNHs was 0.35-0.54 g/g depending on the sizes and numbers of holes on the oxSWNHs. PSL was adsorbed on both the outside and the inside of the oxSWNHs, and released quickly in a couple of hours and slowly within about one day from the respective places. The released quantity in culture medium strongly depended on the concentration of the PSL-oxSWNH complexes, suggesting that PSL adsorbing on oxSWNHs and PSL in the culture medium were in concentration equilibrium. The local injection of PSL-oxSWNHs into the tarsal joint of rats with collagen-induced arthritis (CIA) slightly retarded the progression of the arthritis compared with controls. By histological analysis of the ankle joint, the anti-inflammatory effect of PSL-oxSWNHs was also observed.
Nanotechnology 11/2011; 22(46):465102. · 3.98 Impact Factor
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ABSTRACT: A soluble hybrid nanomaterial that combines fullerenes and carbon nanohorns (CNHs) has been prepared and fully characterized. Electrochemical investigations revealed that the CNHs modify the electron accepting ability of C(60) in the hybrid material.
Chemical Communications 11/2011; 47(48):12771-3. · 6.17 Impact Factor
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ABSTRACT: Semiconducting single-wall carbon nanotubes (SWCNTs) having large diameters (d(t) > 1.3 nm) are successfully extracted in toluene by fluorene-based polymers. In particular, poly(9,9-dioctylfluorene-alt-benzothiadiazole) shows excellent selectivity for (15,4) SWCNTs. Although the importance of structural matching between the fluorene backbone and the tube surface has already been discussed, the present photoluminescence studies reveal that matching the energy levels between fluorene-based polymers and SWCNTs is crucial for selective nanotube extractions.
Journal of the American Chemical Society 08/2011; 133(31):11908-11. · 9.91 Impact Factor
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ABSTRACT: Single-walled carbon nanohorns (SWNHs) intravenously administered to mice did not show severe toxicity during a 26-week test period, which was confirmed by normal gross appearance, normal weight gain and the lack of abnormality in the tissues on histological observations of the mice. SWNH biodistribution was influenced by chemical functionalization. Accumulation of SWNH in the lungs reduced as SWNH hydrophilicity increased; however, the most hydrophilic SWNHs modified with bovine serum albumin (BSA) were most likely to be trapped in the lungs, suggesting that the BSA moiety enhanced macrophage phagocytosis in the lungs. Clearance of some of the hydrophobic SWNHs from the lungs was observed, the mechanism of which is briefly discussed.
Nanotechnology 07/2011; 22(26):265106. · 3.98 Impact Factor
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Haruka Kyakuno,
Kazuyuki Matsuda,
Hitomi Yahiro,
Yu Inami,
Tomoko Fukuoka,
Yasumitsu Miyata,
Kazuhiro Yanagi,
Yutaka Maniwa,
Hiromichi Kataura,
Takeshi Saito,
Motoo Yumura, Sumio Iijima
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ABSTRACT: Studies on confined water are important not only from the viewpoint of scientific interest but also for the development of new nanoscale devices. In this work, we aimed to clarify the properties of confined water in the cylindrical pores of single-walled carbon nanotubes (SWCNTs) that had diameters in the range of 1.46 to 2.40 nm. A combination of x-ray diffraction (XRD), nuclear magnetic resonance, and electrical resistance measurements revealed that water inside SWCNTs with diameters between 1.68 and 2.40 nm undergoes a wet-dry type transition with the lowering of temperature; below the transition temperature T(wd), water was ejected from the SWCNTs. T(wd) increased with increasing SWCNT diameter D. For the SWCNTs with D = 1.68, 2.00, 2.18, and 2.40 nm, T(wd) obtained by the XRD measurements were 218, 225, 236, and 237 K, respectively. We performed a systematic study on finite length SWCNT systems using classical molecular dynamics calculations to clarify the effect of open ends of the SWCNTs and water content on the water structure. It was found that ice structures that were formed at low temperatures were strongly affected by the bore diameter, a = D - σ(OC), where σ(OC) is gap distance between the SWCNT and oxygen atom in water, and the number of water molecules in the system. In small pores (a < 1.02 nm), tubule ices or the so-called ice nanotubes (ice NTs) were formed irrespective of the water content. On the other hand, in larger pores (a > 1.10 nm) with small water content, filled water clusters were formed leaving some empty space in the SWCNT pore, which grew to fill the pore with increasing water content. For pores with sizes in between these two regimes (1.02 < a < 1.10 nm), tubule ice also appeared with small water content and grew with increasing water content. However, once the tubule ice filled the entire SWCNT pore, further increase in the water content resulted in encapsulation of the additional water molecules inside the tubule ice. Corresponding XRD measurements on SWCNTs with a mean diameter of 1.46 nm strongly suggested the presence of such a filled structure.
The Journal of chemical physics 06/2011; 134(24):244501. · 3.09 Impact Factor
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Koki Urita,
Yuichi Shiga,
Toshihiko Fujimori,
Taku Iiyama,
Yoshiyuki Hattori,
Hirofumi Kanoh,
Tomonori Ohba,
Hideki Tanaka,
Masako Yudasaka, Sumio Iijima,
Isamu Moriguchi,
Fujio Okino,
Morinobu Endo,
Katsumi Kaneko
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ABSTRACT: An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition of KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that KI nanocrystals doped in the nanotube spaces of SWCNHs at pressures below 0.1 MPa had the super-high-pressure B2 phase structure, which is induced at pressures above 1.9 GPa in bulk KI crystals. This finding of the supercompression function of the carbon nanotubular spaces can lead to the development of a new compression-free route to precious materials whose syntheses require the application of high pressure.
Journal of the American Chemical Society 06/2011; 133(27):10344-7. · 9.91 Impact Factor
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ABSTRACT: Edge structures and atomic defects can significantly affect the physical and chemical properties of low-dimensional materials, such as nanoribbons, and therefore merit a thorough investigation at the atomic scale. Here, we successfully discriminate single atoms on a monolayered tungsten disulphide nanoribbon by means of time-resolved annular dark-field imaging and spatially resolved electron energy-loss spectroscopy. We unambiguously identify and successfully visualize in motion atomic defects, such as vacancies and edge atoms, using scanning transmission electron microscopy. We also report a direct observation of slip deformation in the nanoribbons and present evidence demonstrating that the deformation process involves the migration of vacancies and rearrangement of tungsten atoms. Single-atom defects are successfully observed for the first time during plastic deformation.
Nature Communications 03/2011; 2:213. · 7.40 Impact Factor
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Angewandte Chemie International Edition 03/2011; 50(21):4853-7. · 13.45 Impact Factor
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ABSTRACT: A novel composite is presented as a supercapacitor electrode with a high maximum power rating (990 kW/kg; 396 kW/l) exceeding power performances of other electrodes. The high-power capability of the electrode stemmed from its unique meso-macro pore structure engineered through the utilization of single-walled carbon nanotubes (20 wt %) as scaffolding for single-walled carbon nanohorns (80 wt %). The novel composite electrode also exhibited durable operation (6.5% decline in capacitance over 100 000 cycles) as a result of its monolithic chemical composition and mechanical stability. The novel composite electrode was benchmarked against another high-power electrode made from single-walled carbon nanotubes (Bucky paper electrode). While the composite electrode had a lower surface area compared to the Bucky paper electrode (280 vs 470 m(2)/g from nitrogen adsorption), it had a higher meso-macro pore volume (2.6 vs 1.6 mL/g from mercury porosimetry) which enabled the composite electrode to retain more electrolyte, ensuring facile ion transport, hence achieving a higher maximum power rating (970 vs 400 kW/kg).
ACS Nano 02/2011; 5(2):811-9. · 10.77 Impact Factor
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ABSTRACT: The microwave-assisted functionalization of carbon nanohorns (CNHs) via [2+1] nitrenes cycloaddition, providing well dispersible hybrid materials possessing aziridino-rings covalently grafted onto the graphitic network of CNHs, was accomplished, while condensation of hydroxy-functionalized CNHs with thioctic acid, furnishing an endocyclic disulfide bond extended from the aziridino-rings, allowed the stabilization of Au nanoparticles.
Chemical Communications 02/2011; 47(5):1604-6. · 6.17 Impact Factor
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ABSTRACT: A recent study showed that carbon nanohorns (CNHs) have biocompatibility and possible medical uses such as in drug delivery systems. It was reported that some kinds of carbon nanomaterials such as carbon nanotubes were useful for bone formation. However, the effect of CNHs on bone tissue has not been clarified. The purpose of this study was to evaluate the effect of CNHs on bone regeneration and their possible application for guided bone regeneration (GBR). CNHs dispersed in ethanol were fixed on a porous polytetrafluoroethylene membrane by vacuum filtration. Cranial defects were created in rats and covered by a membrane with/without CNHs. At two weeks, bone formation under the membrane with CNHs had progressed more than under that without CNHs and numerous macrophages were observed attached to CNHs. At eight weeks, there was no significant difference in the amount of newly formed bone between the groups and the appearance of macrophages was decreased compared with that at two weeks. Newly formed bone attached to some CNHs directly. These results suggest that macrophages induced by CNHs are related to bone regeneration. In conclusion, the present study indicates that CNHs are compatible with bone tissue and effective as a material for GBR.
Nanotechnology 02/2011; 22(6):065102. · 3.98 Impact Factor
