Electron energy-loss spectroscopy of carbon onions

Tomita, Satoshi; Fujii, Minoru; Hayashi, Shinji; Yamamoto, Keiichi

doi:10.1016/s0009-2614(99)00374-7

Cited by 90 publications

(42 citation statements)

References 14 publications

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“…D, TEM image of hyperfullerenes. The so-called onions were fabricated via transformation of the nanodiamond in a TEM (19). The diameters of the larger nanostructures were determined directly through TEM images.…”

Section: Fig 1 Types Of Nanostructures Investigated In This Studymentioning

confidence: 99%

Single-walled Carbon Nanotubes Are a New Class of Ion Channel Blockers

Park¹,

Chhowalla

Iqbal

et al. 2003

Journal of Biological Chemistry

298

209

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Here we identify a novel class of biological membrane ion channel blockers called single-walled carbon nanotubes (SWNTs). SWNTs with diameter distributions peaked at ϳ0.9 and 1.3 nm, C 60 fullerenes, multi wall nanotubes (MWNTs), and hyperfullerenes (nano-"onions") were synthesized by several techniques and applied to diverse channel types heterologously expressed in mammalian cells. External as-fabricated and purified SWNTs blocked K ؉ channel subunits in a dose-dependent manner. Blockage was dependent on the shape and dimensions of the nanoparticles used and did not require any electrochemical interaction. SWNTs were more effective than the spherical fullerenes and, for both, diameter was the determining factor. These findings postulate new uses for SWNTs in biological applications and provide unexpected insights into the current view of mechanisms governing the interaction of ion channels with blocking molecules.Because of the physiological role they play, ion channels exhibit unique structures, including the pore that provides the physical pathway for ion movements across the plasma membrane and several charged domains that attract and/or repel ions (1). These characteristics make ion channels easy targets for external agents such as natural toxins and synthetic drugs that react with them by establishing electrochemical interactions. Thus, blocking agents have been used not only as the basic components for commercial pesticides and potential therapeutic drugs but also to infer functional information (1).The identification of new classes of molecules to target ionchannels is of significant interest in biological research, and, therefore, we sought to explore the possibility of using novel materials such as selected single-walled carbon nanotubes (SWNTs), 1 as ion channel blockers. In recent years there have been several attempts to use nanotubes for biological purposes because of their unique mechanical, chemical, and electrical properties (2). For example, nanotubes have been successfully used for the helical crystallization of proteins (3) and the growth of embryonic rat brain neurons (4) and as potential biosensors and bioreactors (5, 6). Here we show that SWNTs of certain diameters can efficiently block K ϩ channels. MATERIALS AND METHODSNanotubes and Fullerene Synthesis-SWNTs, with a diameter distribution peaked in the 0.8 -0.9 nm range, were grown by chemical vapor deposition (CVD) in a horizontal tube reactor using a three-stage process. In the first stage, the catalyst/support system was obtained via wet mixing followed by combustive calcination. Magnesium nitrate hexahydrate, cobalt nitrate hexahydrate, ammonium heptamolybdate tetrahydrate, and citric acid (the latter to induce combustion) were mixed with enough distilled water to give a clear solution, which was heated to 550°C for 5-10 min in air. The resulting powder of general composition MgO (1-x-y) Co x Mo y (where nanoscale Co-Mo is the catalyst in a typical molybdenum/cobalt atomic ratio of 1:4, and MgO is the catalyst support) was taken out,...

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Section: Fig 1 Types Of Nanostructures Investigated In This Studymentioning

confidence: 99%

Single-walled Carbon Nanotubes Are a New Class of Ion Channel Blockers

Park¹,

Chhowalla

Iqbal

et al. 2003

Journal of Biological Chemistry

298

209

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“…30 OLC also demonstrates high selectivity and catalytic activity in the oxidative dehydrogenation of ethyl benzene to styrene. 31 The properties of OLC produced by annealing ND have been investigated by x-ray emission spectroscopy, 32 Raman spectroscopy, 33 electron energy-loss spectroscopy, 34 electron-spin resonance, 35 x-ray diffraction, 36 and ultraviolet-visible absorption spectroscopy. 37 A photoemission study of potassium intercalated polygonal hollow onions produced at 2140 K showed that these carbon onions behave as small graphite crystals and hence display bulklike rather than molecularlike behavior.…”

Section: Introductionmentioning

confidence: 99%

Photoemission study of onionlike carbons produced by annealing nanodiamonds

et al. 2005

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“…Laboratory experiments have shown that fullerenes and buckyonions are highly stable molecules that can survive the harsh conditions of interstellar space more easily than other carbon aggregates. Within the fullerene family, buckyonions composed of concentric spherical shells are the most stable (Tománek et al 1993;Tomita et al 1999). They can be part of two icosahedral families 60n 2 and 180n 2 with , 2, … .…”

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confidence: 99%

Fullerenes and Buckyonions in the Interstellar Medium

Iglesias‐Groth

2004

ApJ

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We show that photoabsorption by fullerenes and buckyonions (multishell fullerenes) explain the shape, width, and peak energy of the most prominent feature of interstellar absorption, the UV bump at 2175 . The predicted A optical and near-infrared transitions for these molecules also offer a potential explanation for the long-standing problem of the identity of the diffuse interstellar bands. The implied ubiquitous distribution of fullerenes may also account for the anomalous galactic microwave emission detected by cosmic microwave background experiments. Comparing theoretical cross sections and astronomical data, we estimate a density of fullerenes in the diffuse interstellar medium of 0.1-0.2 parts per million, consistent with the findings in meteorites. Fullerenebased molecules appear to be a major carbon reservoir in the interstellar medium.

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Electron energy-loss spectroscopy of carbon onions

Cited by 90 publications

References 14 publications

Single-walled Carbon Nanotubes Are a New Class of Ion Channel Blockers

Single-walled Carbon Nanotubes Are a New Class of Ion Channel Blockers

Photoemission study of onionlike carbons produced by annealing nanodiamonds

Fullerenes and Buckyonions in the Interstellar Medium

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