The special geometry and unique properties of carbonnanotubes offer great potential applications, including nanoelectronic devices, energy storage, chemical probes and sensors, field emission displays, etc. . The electronic properties of single-wallcarbonnanotubes (SWNTs) can be considerably affected by the presence of adsorbed molecules. This has important consequences for device applications that use SWNTs as the bases of chemical sensors. Advantages of carbonnanotubes (CNTs) over other materials as good sensors are due to their small size, high strength, high electrical and thermal conductivity, and high specific area. The effects of absorbance of gas on SWNTs were studied theoretically and experimentally [2– 6].
We report the synthesis and characterization of one-dimensional silver nanostructures using single-wallcarbonnanotubes (SWCNT) as a template material. Transmission electron microscopy and scanning tunneling microscopy are consistent with the formation of a one-dimensional array of silver particles on SWCNT. We observe evidence for the excitation of the longitudinal silver plasmon mode in the optical absorption spectra of Ag-SWCNT dispersions, even in the lowest silver concentrations employed. The results indicate that silver deposits on SWCNT may be candidates for light-to-energy conversion through the coupling of the electric field excited in arrays of plasmonic particles.
Carbonnanotubes are of great research interest because they are used in physical, chemical, and nanotechnological applications since the discovery of singlewallcarbonnanotubes (SWCNTs) [1, 2]. Due to specific chemical and physical properties of carbonnanotubes, their practical applications have been extended in design of sensors, energy storage, electrochemical and electronic devices  and advanced technological innovation . The electrical characteristic of SWCNTs depends on their chirality (n, m) and tube diameter . The length and the sidewall curvature have influence on electronic structure and energetics of a nanotube [5- 9]. Due to large current carrying capacity and thermal stability of metallic carbon
Lack of control on the chirality or diameter of single-wallcarbonnanotubes (SWCNTs) during synthesis is a major impediment in the path of their widespread commercialization. We demonstrate that the humble technique of catalytic chemical vapor deposition of methane, without any sophisticated catalyst preparation, can provide significant control on the diameter of the synthesized SWCNTs. The catalyst used is a solid solution of the bimetals Fe-Mo or Co-Mo in MgO. The radial breathing modes (RBMs) in the Raman spectra of SWCNTs were used to find out the diameters. Kataura plot along with RBMs was used to study the chirality of the tubes. High concentration of the catalysts (Co:Mo:MgO = 1:0.5:15 and Fe:Mo:MgO = 1:0.5:30) resulted in high yields. However, most of these carbonaceous materials were impurities. Reducing the concentration not only improved the purity and crystallinity (I D /I G ratio ~ 0.1), but
This tool simulates electron transport in single-walled carbonnanotubes using an up winding discretization of the Boltzmann transport equation in the relaxation time approximation . Users can select chirality and length of the nanotube, as well as the applied voltage across the tube and the temperature of the environment. The simulator can also be adjusted by setting the number of points in the discretization. Simulation is performed in both space and momentum, represented by the number of points Nx and Nk in the x-direction (space) and k- direction (momentum). The length of the simulation depends on the size of the time step, and the number of steps taken in the simulation. The maximum size of the time step is limited by stability criteria, and the tool will warn the user and adjust the step to achieve stability if it is set too large. The simulator  can be run in three distinct modes: single voltage, voltage sweep, and length sweep.
Abstract: The clinical management of bone defects caused by trauma or nonunion fractures remains a challenge in orthopedic practice due to the poor integration and biocompatibility properties of the scaffold or implant material. In the current work, the osteogenic properties of carboxyl-modified single-walled carbonnanotubes (COOH–SWCNTs) were investigated in vivo and in vitro. When human preosteoblasts and murine embryonic stem cells were cultured on coverslips sprayed with COOH–SWCNTs, accelerated osteogenic differentiation was manifested by increased expression of classical bone marker genes and an increase in the secretion of osteocalcin, in addition to prior mineralization of the extracellular matrix. These results predicated COOH–SWCNTs’ use to further promote osteogenic differentiation in vivo. In contrast, both cell lines had difficulties adhering to multi-walled carbon nanotube-based scaffolds, as shown by scanning electron microscopy. While a suspension of SWCNTs caused cytotoxicity in both cell lines at levels 20 μ g/mL, these levels were never achieved by release from sprayed SWCNTs, warranting the approach taken. In vivo, human allografts formed by the combination of demineralized bone matrix or cartilage particles with SWCNTs were implanted into nude rats, and ectopic bone formation was analyzed. Histological analysis of both types of implants showed high permeability and pore connectivity of the carbon nanotube-soaked implants. Numerous vascularization channels appeared in the formed tissue, additional progenitor cells were recruited, and areas of de novo ossification were found 4 weeks post-implantation. Induction of the expression of bone-related genes and the presence of secreted osteopontin protein were also confirmed by quantitative polymerase chain reaction analysis and immunofluores- cence, respectively. In summary, these results are in line with prior contributions that highlight the suitability of SWCNTs as scaffolds with high bone-inducing capabilities both in vitro and in vivo, confirming them as alternatives to current bone-repair therapies.
Females receiving up to 10 μg/mouse of PEG- SWCNTs did not carry any abnormal fetus nor displayed tissue histological alterations. By contrast, at the highest concentration tested we observed fetal abnormalities in one in ten dams (1/10) exposed to a single injection of 30 μg/mouse (1 malformed embryo) and in 2 out of 10 dams exposed to the three refracted doses of 10 μg/ mouse each (5 malformed embryos). In both groups similar fetal malformations were observed, consisting in delayed development of the paws and head abnormal- ities. In 4 fetuses out of 6, these malformations were as- sociated with reduced length (around 1.2-1.3 cm), which was out of two standard deviations in comparison to our internal growth reference curves. The main results of these experiments are summarized in Table 1.
For proper utilization of either AC or SWNT, they must be characterized for structural properties and surface chemistry. For the former, adsorption of nitrogen or argon at their respective boiling points is commonly used. As alternative to these common molecular probes, we believe water could also be used and it is more economical because adsorption of water can be carried out at ambient temperature while argon and nitrogen are used under cryogenic conditions. However the limitation of using water lies in the fact that water does not fill mesopores, and therefore its use is limited to the determination of micropores. Since ACs are mainly microporous, the use of water for characterization should be established and validated with a wide range of microporous samples. While adsorption of non-polar gases, such as argon, and weakly polar gases, such as nitrogen, is well studied both theoretically and experimentally , water adsorption exhibits a different behavior because of the strong adsorbate-adsorbate interactions (hydrogen bonding) . For a carbon surface, the interaction between a water molecule and a graphene surface is much weaker than the intermolecular interaction of water, and therefore water adsorption in porous carbon only occurs when its surfaces contain functional groups. Therefore, the aim of this paper is to use graphitic slit pores with functional groups to model AC and bundles of SWNT with functional group to investigate the mechanism of water adsorption, and the isotherms obtained for different pore sizes are then used as a kernel to determine micropore size distributions of ACs and SWNTs.
Iijima  found after his electron diffraction analysis that carbonnanotubes ranging 4 to 30 nanometers (nm) in diameter have helical multi-walled structures. Single- wall nanotube (SWNT) has about one nanometer in di- ameter and micrometers (μm) in length. Ebbesen et al.  measured the electrical conductivity of individual carbonnanotubes and found that varies depending of the temperature T, the tube radius r and the pitch p. Ex- periments show that SWNT can be either semiconducting or metallic, depending on how they are rolled up from the graphene sheets . In the present work we shall present a microscopic theory of the electrical conductiv- ity of semiconducting SWNT, starting with a graphene honeycomb lattice, developing a Bloch electron dynam- ics based on a rectangular cell model , and using ki- netic theory. A SWNT can be formed by rolling a gra- phene sheet into a circular cylinder. The graphene which forms a honeycomb lattice is intrinsically anisotropic as we shall explain it in more detail later in Section 2. Mo- riyama et al.  fabricated 12 SWNT devices from one chip, and observed that two of the SWNT samples are semiconducting and the other 10 are metallic. The semi- conducting SWNT samples show an activated-state tem-
Recently, we have demonstrated a novel modification approach, plasma treatment, to modify the polystyrene microspheres surface with hydroxyl groups . In this whole modification process, no more solvent and chemicals are involved, which simplifies the modification process, reduces the preparation cost, and decreases the hazard to environment. Herein, we explored this simple, low-cost, and green protocol to introduce the hydroxyl groups on the side walls of singlewallcarbonnanotubes (SWCNTs) and use these surface-modified SWCNTs as substrate to fabri- cate SiO 2 -coated SWCNTs (SWCNT@SiO 2 ) nanocom-
In this work, using quantum mechanics, the interaction of drug carvedilol with (5, 5) COOH functionalized singlewallcarbonnanotubes (SWNT) have been studied. All of the calculations have been performed using a hybrid density functional method (B3LYP) in gas and solution phases. Two possible modes of covalent interaction of carvedilol onto COOH functionalized SWNT were investigated. Quantum molecular descriptors and frontier orbital analysis in the drug- nanotube systems were studied. It was found that bonding of carvedilol to COOH functionalized carbonnanotubes through hydroxyl group is stronger than amino group.
sults extracted from tests on different combinations. Burke studied on the electrical properties of nano- tubes at high frequency by extracting the electrical equivalent circuit of singlewallcarbonnanotubes [43, 44]. Within the recent decade, considering the simple structure of singlewallcarbonnanotubes comparing to double and multiwall ones, these types of carbonnanotubes have received more attentions. Consider- able advancements in this context ultimately resulted in accessing to functional specifications of a singlewallcarbon nanotube and bundle of singlewallcarbonnanotubes [44, 45]. For instance, researches have been performed to establish equivalent circuit of a SWCNT [44, 46] and ultimately resulted in functional predic- tions of SWCNT connections . In some papers, the dependence of nanotubes diameter for connection and Ohmic resistances of a bundle of SWCNT which are very important for implementation of nanotubes connections, have been evaluated . The maximum value of conductive channel per cross-section area is required to reach the maximum conductivity in the applications of CNTs interconnections. Naeemi and Meindl  examined and calculated the number of conductive channels available in MWCNT by the ap- proximate method and also presented a physical mod- el of MWCNT.
Abstract: The aim of this study was to explore whether single-wallcarbonnanotubes (SWCNTs) can be used as artery tissue-engineering materials by promoting vascular adventitial fibroblasts (VAFs) to transform into myofibroblasts (MFs) and to find the signal pathway involved in this process. VAFs were primary cultured and incubated with various doses of SWCNTs suspension (0, 0.8, 3.2, 12.5, 50, and 200 µg/mL). In the present study, we used three methods (MTT, WST-1, and WST-8) at the same time to detect the cell viability and immunofluorescence probe technology to investigate the effects of oxidative injury after VAFs incubated with SWCNTs. Immunocytochemical staining was used to detect SM 22 -α expression to confirm whether VAFs transformed into MFs. The protein levels were detected by western blotting. The results of immunocytochemical staining showed that SM 22 -α was expressed after incubation with 50 µg/mL SWCNTs for 96 hours, but with oxidative damage. The mRNA and protein levels of SM 22 -α, C-Jun N-terminal kinase, TGF-β 1 , and TGF-β receptor II in VAFs increased with the dose of
We report here the development of a resistive singlewallcarbonnanotubes (SWCNTs) sensor, based on a CMOS substrate that responds at ambient temperature to ppm levels of ammonia. The power efficient CMOS micro- hotplate is a thin membrane structure and comprises metal heater with an interdigitated electrode. The SWCNTs film was prepared first by treatment with aqua regia solution, followed by washing with distilled water, and then treated with ascorbic acid at 95°C. The film was deposited by simply dipping the chip into the solution. The SWCNTs showed good response to ammonia in a humid nitrogen atmosphere.
Singlewallcarbonnanotubes (SWCNTs) are being investigated for many power generation and storage technologies which rely on amorphous carbon/graphite for conductive electrodes including Li + batteries 14, 24 , proton exchange membrane fuel cells 25 , and super capacitors 15 . Of the prevalent approaches used to produce SWCNTs for these applications, laser vaporization synthesis presents certain advantages, including tunable SWCNT chirality distributions 26 and well established purification processes 13 . The intent to increase SWCNT yield during the laser synthesis process has resulted in various studies on the experimental parameters’ including reactor temperature, pressure, and catalyst composition 27-31 . However, until recently, the lack of a calibrated purity assessment method precluded these early reports from validating the degree of change that these parameters had on the purity (defined as the total mass fraction of SWCNTs, w SWCNTs ) of SWCNTs contained in a sample. Although empirical analysis has suggested that a
the classical electrodynamics and a semi-classical kinetic theory, they derived the dispersion relation of surface wave in CN’s. They found out that the CNs can be used as a waveguide for controlling electromagnetic wave propagation in specified frequency ranges (examples are infrared and optical). They also presented a general quantum mechanical theory of the conductivity of a singlewallcarbonnanotubes with interband transitions.
History of carbon is difficult to trace although it is as old as human civilization. Charcoal was used for water purification and adsorbent by ancient Hindus in India, and wood charcoal as an adsorbent and purifying agent by Egyptians and Sumerians as early as 3750 to 1500BC . ‘Indian inks’ made from soot were used in the oldest Egyptian herioglyps on papyrus. Although activated charcoal, an allotrope of carbon is generally used as decolorizing agent in metallurgical operation, the use of carbon nanomaterials has been recognised in the re- cent years. A wide variety of carbon-based nanomater- ials such as fullerene, fullerene cages, single-wallcarbonnanotubes (SWCNTs) and multi-wallcarbonnanotubes (MWCNTs) have been prepared. Diameters of SWCNTs and MWCNTs are typically between 0.8 to 2 nm and, 5 to 20 nm respectively, although MWCNTs diameters can exceed 100 nm. CNTs length ranges from less than 100 nm to several cm, thereby bridging molecular and macroscopic scales. Fullerenes are cage-like structures comprising of twelve 5-member carbon and unspecified 6-member rings in defect-free form. Even though an
Micrographs of mesenchymal stem cells differentiated to adipocytes on circularly patterned SAMs with varying diameters (top row) and durations (left column). …………………………………………………. (Top) Three-dimensional plot comparing differentiation rate versus time versus cell circular pattern size. From the data, there is no significant change in the differentiation rate by increasing the circular pattern size and therefore increasing the cell population. The data were normalized to 1.0 for fully differentiated cells after 10 days. (Bottom) Gel comparison example of the rate of adipogenic differentiation via gene expression for 220 μm circles. An adipose-specific gene, liproprotein lipase (Lpl), and a control gene, β2-microglobulin (β2mg), were used to ensure equal loading of the DNA. hMSCs were cultured until confluent and then induced to adipose and monitored. Total RNA was extracted and analyzed by reverse transcription PCR. Lane 1, control cells; lanes 2-6, days of induced differentiation. ……………………………………. Representative micrographs of mesenchymal stem cells differentiated to adipocytes on varying geometrical patterns and durations………………. Three-dimensional plot comparing differentiation rate versus time versus geometry…………………………………………………………………. Scheme of tailoring gold nanorods with an electroactive chemoselective immobilization strategy. ………………………………………………… Electrochemical characterization on gold nanorods……………………... Scanning electron micrograph images of cells on gold nanorods……….. Comparison of phase contrast images of mesenchymal stem cells on flat gold and nanorods surfaces……………………………………………… Strategy to chemoselectively tailor singlewallcarbonnanotubes (CNT) by combining π-π stacking and electroactive immobilization…………… Eelctrochemical characterization of ligand immobilization to the electroactive hydroquinone carbon nanotube (H 2 Q-CNT) ………………