Development Of Carbon Nanotubes Research Articles

Single-wall carbon nanotubes based anticancer drug delivery system

Conventional administration of chemotherapeutic agents is compromised by their lack of selectivity which is the cause of a lethal effect accomplishment on healthy tissues. Since therapeutic and diagnostic agents could functionalize the structure of carbon nanotubes (CNTs), the development of CNTs as drug containers would pave the way to their employment as nanovectors into the cells. Here a study on cisplatin (Cis-Diamminedichloroplatinum (CDDP) – a platinum-based chemotherapy drug) embedding to single-wall CNTs (SWCNTs) is shown.Being sure that the anticancer drug discharge occurred, in vitro analysis have been performed. The inhibition of prostate cancer cells (PC3 and DU145) viability from tubes encapsulating cisplatin proved the efficiency of the produced delivery system.

Influence of oxygen on the growth of carbon nanotubes by the SiC surface decomposition method

The influence of oxygen on the development of carbon nanotubes (CNTs) during the annealing process of the surface decomposition method on SiC(000−1) surfaces was investigated. In the case of annealing a SiC substrate under ultra-high vacuum conditions, carbon nanofibers (CNFs) form between the CNT layer and the substrate. However, CNTs form without CNFs by annealing the substrate in an oxygen atmosphere. The mean length of CNTs is longer than those formed without an oxygen atmosphere. From cross-sectional transmission electron microscopy images, it was found that oxygen plays an important role in CNT growth by the surface composition method.

Development of carbon nanotubes and nanofluids based microbial fuel cell

In the present study, the construction of a novel microbial fuel cell (MFC) using novel electron mediators and carbon nanotube (CNT) based electrodes has been discussed. The novel mediators are nanofluids which were prepared by dispersing nanocrystalline platinum anchored carbon nanotubes (CNTs) in water. A cation selective membrane separates the two chambers of the MFC with hexacyanoferrate as the ultimate electron acceptor in the cathode compartment. Performance of the new Escherichia coli based MFC was compared to the previously reported E. coli based microbial fuel cells with Neutral Red (NR) and Methylene Blue (MB) electron mediators. The performance of the MFC using CNT based nanofluids and CNT based electrodes has been compared against plain graphite electrode-based MFC. CNT based electrodes showed as high as ∼6-fold increase in the power density (2470 mW/m 2) compared to graphite electrodes (386 mW/m 2). The present work demonstrates the potential of noble metal nanoparticles dispersed on CNTs based MFC for the generation of high energies from even simple bacteria like E. coli.

Preparation and properties of natural rubber composites reinforced with pretreated carbon nanotubes

AbstractIn order to achieve dramatic improvements in the performance of rubber materials, the development of carbon nanotube (CNT)‐reinforced rubber composites was attempted. The CNT/natural rubber (NR) nanocomposite was prepared through solvent mixing on the basis of pretreatment of CNTs. Thermal properties, vulcanization characteristics, and physical and mechanical properties of the CNT/NR nanocomposites were characterized in contrast to the carbon black (CB)/NR composite. Through the addition of the CNTs treated using acid bath followed by ball milling with HRH (hydrated silica, resorcinol, and hexamethylene tetramine) bonding systems, the crystallization melting peak in differential scanning calorimetry (DSC) curves of NR weakened and the curing rate of NR slightly decreased. Meanwhile, the over‐curing reversion of CNT/NR nanocomposites was alleviated. The dispersion of the treated CNTs in the rubber matrix and interfacial bonding between them were rather good. The mechanical properties of the CNT‐reinforced NR showed a considerable increase compared to the neat NR and traditional CB/NR composite. At the same time, the CNT/NR nanocomposites exhibited better rebound resilience and dynamic compression properties. The storage modulus of the CNT/NR nanocomposites greatly exceeds that of neat NR and CB/NR composites under all temperature regions. The thermal stability of NR was also obviously improved with the addition of the treated CNTs. Copyright © 2008 John Wiley & Sons, Ltd.

CVD oriented growth of carbon nanotubes using AlPO4-5 and L type zeolites

Control over single wall carbon nanotube structure, positioning and orientation is one of the main challenges for the development of carbon nanotube based electronics. A novel approach consists in ...

Characterization and compression properties of injection molded carbon nanotube composites

AbstractSince the development of carbon nanotubes (CNTs) in 1991, they have received much attention with improved mechanical, thermal, and electrical properties of their composites compared to common polymer composites. The CNTs are currently used to increase the modulus of common thermoplastics and thermosets, including urethanes and epoxies. The CNTs are difficult to disperse within any media because of limited chemical reactivity and potential agglomeration in their “as grown” state. This study evaluated the effect of incorporating bundled and unbundled CNTs at different concentrations into Polyurethane/CNT/woven fiber reinforced composites. Optical microscopy and atomic force microscopy (AFM) characterized the dispersion of CNTs within the polymer matrix in injection molded CNT/polyurethane composites. Polyurethane/CNT/woven fiber reinforced composite plaques were prepared and then characterized by mechanical compression testing. Optical microscopy and AFM qualitatively determined a decreased agglomerate size resulting in improved mechanical properties. Results of this study show significant differences in yield stress, stress at failure, and modulus of elasticity within the various treatments. No significant differences were found for yield strain, strain at failure, and toughness. However, the conservativeness of the statistical model warrants further investigation for strain at failure and toughness with possible interaction effects of CNT concentration for each composite. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Development of Carbon Nanotube based radiation detectors

Multi Wall Carbon NanoTubes (MWCNT) are one-dimensional structures with diameters ranging between 5 and 30 nm and lengths up to hundreds of micrometers. They show a metallic-like behaviour and enhanced field emission capability; their sensitivity to the radiation is very peculiar, depending on their diameter and chirality. The wide range of their bandgaps (from 0.4 to ≈ 6 eV) makes these devices very suitable for fabrication of sensors of electromagnetic radiation, from UV to IR. This opens the possibility to build wide sensitive range radiation detectors for space researches and environmental controls. Preliminary tests have been performed by exposing a prototype detector made up of a MWCNT carpet grown by the CVD technique between two gold electrodes on a 500 micrometer thick silicon substrate to pulsed UV, visible and IR radiation. First results on the charge generated by pulsed laser are reported.

Carbon Nanotube–Magnetite Composites, With Applications to Developing Unique Magnetorheological Fluids

The development of carbon nanotube (CNT) based technology is limited in part by the lack of effective bulk methods for precisely manipulating and aligning nanotubes at the very fine scale. Moreover, the innate hydrophobic and inert nature of the CNT surface limits their compatibility with aqueous systems and flexibility for surface chemistry functionalization. This paper assesses the variety of methods developed to couple magnetically susceptible components such as ferromagnetic material with CNTs in order to overcome these limitations. In addition to reviewing the past 16 years of relevant literature, our own methods for noncovalent surface coating of CNT’s with magnetite nanoparticles are described. The application of such composites is then explored within the framework of a magnetorheological (MR) fluid. It is found that the addition of magnetite nanoparticles to a MR fluid enriches the available MR response, resulting, in some cases, in an increased sedimentation stability, larger saturation critical stresses, and faster response to time varying magnetic fields. Finally, our own composite based MR fluid is discussed, and shown to possess a field dependent response that is a hybrid between that observed in ferrofluids and conventional MR fluids.

Development of carbon nanotube and carbon xerogel supported catalysts for the electro-oxidation of methanol in fuel cells

Multiwalled carbon nanotubes and high surface area mesoporous carbon xerogel were prepared and used as supports for monometallic Pt and bimetallic Pt–Ru catalysts. In order to assess the influence of the oxygen surface groups of the support, the mesoporous carbon xerogel was also oxidized with diluted oxygen before impregnation. Various reduction protocols were tested, the best results corresponding to reduction with sodium borohydride. High dispersion catalysts were obtained, which showed quite good performance in the electro-oxidation of methanol. In particular, a remarkable increase in the activity was observed when the Pt–Ru catalysts were supported on the oxidised xerogel. This effect was explained in terms of the metal oxidation state, as shown by XPS. It has been shown that the oxidised support helps to maintain the metals in the metallic state, as required for the electro-oxidation of methanol. This effect was negligible in the case of the Pt catalysts.

Lower hepatitis C virus infections in seropositive patients between 1999 and 2003

Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer CNTs. To pursue safety by design, the redox potential in reactions with CNTs has been contemplated recently. However, the chemical reactivity of CNTs has not been explored kinetically, so that there is no scheme to express a redox reaction with CNTs, though it has been investigated and reported. In addition, the reactivity of CNTs is discussed with regard to impurities that consist of transition metals in CNTs, which obfuscates the contribution of CNTs to the reaction. The present work aimed at modeling CNT scavenging in aqueous solution using a kinetic approach and a simple first-order reaction scheme. The results show that CNTs follow the redox reaction assumption in a simple chemical system. As a result, the reaction with multiwalled CNTs is semiquantitatively denoted as redox potential, which suggests that their biological reactions may also be evaluated using a redox potential scheme.

Ultrasound-induced Functionalization and Solubilization of Carbon Nanotubes for Potential Nanotextiles Applications

AbstractA simple sonochemical method has been employed for the surface functionalization of carbon nanotubes. Pristine single-walled carbon nanotubes (SWNTs) were irradiated by ultrasound in methyl methacrylate monomer. Polymer grafted carbon nanotubes were easily prepared by in situ sonochemically initiated radical polymerization of methyl methacrylate. FT-IR, TGA, SEM and TEM were used to characterize the polymethyl methacrylate (PMMA) grafted SWNTs. The surface-modified SWNTs afforded are then dispersible in good solvents for PMMA, such as dichloromethane and chloroform. The ‘green’ value involved in this simplifying processing contains low hazard, clean operation, reduced chemical consumption and short time, which undoubtedly generate profound impact on the development of carbon nanotube based nanochemistry and large scale nanotextiles application.