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The production of single-wall carbon nanotubes with controlled diameter distributions by laser ablation is enabled by simple introduction of Fe into a conventional NiCo catalyst. The Fe helps increase the aggregation rate of metal in laser ablation and enlarges the crystal lattice constant of metal catalysts because of a change in the crystal structure from Ni to Ni3Fe, NiFe2, which then results in the enlargement of metal particles and the growth of larger diameter SWNTs.

We incorporated cisplatin inside single-wall carbon nanohorns (NHs) and revealed that 70% of the cisplatin was released from NHs having holes with hydrogen-terminated edges when they were immersed in phosphate-buffered saline (PBS). However, only 15% was released from NHs having holes with oxygen-containing functional groups at the hole edges (NHox). Elemental analysis indicated that −COOH and −OH groups at the hole edges of NHox changed mainly to −COONa and −ONa groups by immersion in PBS. These groups decreased the practical hole diameters, which resulted in hindering the cisplatin release from NHox. This means that the release of the material from inside NHox would be controlled by chemically modifying the functional groups attached to the hole edges of NHox; thus the potential applicability of NHox to a material carrier would be enhanced. [ABSTRACT FROM AUTHOR]

Due to the simplicity of the process, holes in the graphene walls of single-wall carbon nanotubes (SWNTs) and single-wall carbon nanohorns (SWNHs) have often been opened using O2 gas at high temperatures, even though this contaminates the nanotubes with carbonaceous dust (C-dust). To open holes with less C-dust contamination, we found that a slow temperature increase of 1 °C/min or less, in air, was effective. We also found that SWNHs having little C-dust could store a large quantity of materials inside the tubes. We infer that the local temperature increase due to the exothermic reaction of combustion may have been suppressed in the slow combustion process, which was effective in reducing the C-dust. [ABSTRACT FROM AUTHOR]

The large diameter of single-wall carbon nanohorns (SWNHs) allows various molecules to be easily incorporated in hollow nanospaces. In this report, we prove that the nanospaces of SWNHs even work as the chemical reaction field at high temperature; that is, Gd-acetate clusters inside SWNHs were transformed into ultrafine Gd2O3 nanoparticles with their particle size retained even after heat-treatment at 700 °C. This indicates that the confinement of the Gd-acetate clusters in a deep potential well of the SWNH nanospaces prevented a migration to form larger particles, giving rise to ultrafine Gd2O3 nanoparticles of 2.3 nm in average diameter, which is much smaller than the case without SWNHs. The Gd2O3 nanoparticles thus obtained were demonstrated to be actually useful to the magnetic resonance imaging. We believe that the presented effectiveness of the inner hollow spaces of SWNHs, therefore, also those of the carbon nanotubes, for high-temperature chemical reactions should be highlighted, and that the thus produced novel nanomaterials are promising to expand the fields of nanoscience. [ABSTRACT FROM AUTHOR]