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Sample records for carbon nanotubes modified

  1. Photothermal effects of immunologically modified carbon nanotubes

    Science.gov (United States)

    Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

    2013-02-01

    Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

  2. Modified carbon nanotubes and methods of forming carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  3. Improved Composites Using Crosslinked, Surface-Modified Carbon Nanotube Materials

    Science.gov (United States)

    Baker, James Stewart

    2014-01-01

    Individual carbon nanotubes (CNTs) exhibit exceptional tensile strength and stiffness; however, these properties have not translated well to the macroscopic scale. Premature failure of bulk CNT materials under tensile loading occurs due to the relatively weak frictional forces between adjacent CNTs, leading to poor load transfer through the material. When used in polymer matrix composites (PMCs), the weak nanotube-matrix interaction leads to the CNTs providing less than optimal reinforcement.Our group is examining the use of covalent crosslinking and surface modification as a means to improve the tensile properties of PMCs containing carbon nanotubes. Sheet material comprised of unaligned multi-walled carbon nanotubes (MWCNT) was used as a drop-in replacement for carbon fiber in the composites. A variety of post-processing methods have been examined for covalently crosslinking the CNTs to overcome the weak inter-nanotube shear interactions, resulting in improved tensile strength and modulus for the bulk sheet material. Residual functional groups from the crosslinking chemistry may have the added benefit of improving the nanotube-matrix interaction. Composites prepared using these crosslinked, surface-modified nanotube sheet materials exhibit superior tensile properties to composites using the as received CNT sheet material.

  4. Nanocomposite fibers and film containing polyolefin and surface-modified carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Chu,Benjamin (Setauket, NY); Hsiao, Benjamin S. (Setauket, NY)

    2010-01-26

    Methods for modifying carbon nanotubes with organic compounds are disclosed. The modified carbon nanotubes have enhanced compatibility with polyolefins. Nanocomposites of the organo-modified carbon nanotubes and polyolefins can be used to produce both fibers and films having enhanced mechanical and electrical properties, especially the elongation-to-break ratio and the toughness of the fibers and/or films.

  5. Carbon nanotube nanocomposite-modified paper electrodes for supercapacitor applications

    Science.gov (United States)

    Korivi, Naga S.; Vangari, Manisha; Jiang, Li

    2017-02-01

    This paper describes the evaluation of carbon paper electrodes for supercapacitor applications. The electrodes are based on carbon micro-fiber paper modified with active material consisting of layers of silver nano-particulate ink and a nanocomposite of multi-walled carbon nanotubes and silver nano-particulate ink. The electrodes were characterized microscopically and electrically. Current-voltage studies revealed a consistent Ohmic behavior of the electrode when modified with different nanostructured active material. Among the active materials incorporated into the electrode, a nanocomposite of carbon nanotubes and silver nano-particulate ink significantly improved capacitance. The paper electrodes can be used for lightweight and ultrathin supercapacitors and other portable energy applications.

  6. Carbon nanotube nanocomposite-modified paper electrodes for supercapacitor applications

    Science.gov (United States)

    Korivi, Naga S.; Vangari, Manisha; Jiang, Li

    2016-12-01

    This paper describes the evaluation of carbon paper electrodes for supercapacitor applications. The electrodes are based on carbon micro-fiber paper modified with active material consisting of layers of silver nano-particulate ink and a nanocomposite of multi-walled carbon nanotubes and silver nano-particulate ink. The electrodes were characterized microscopically and electrically. Current-voltage studies revealed a consistent Ohmic behavior of the electrode when modified with different nanostructured active material. Among the active materials incorporated into the electrode, a nanocomposite of carbon nanotubes and silver nano-particulate ink significantly improved capacitance. The paper electrodes can be used for lightweight and ultrathin supercapacitors and other portable energy applications.

  7. ELECTROANALYTICAL APPLICATIONS OF CARBOXYL-MODIFIED CARBON NANOTUBE FILM ELECTRODES

    Institute of Scientific and Technical Information of China (English)

    C.G. Hu; W.L. Wang; K.J. Liao; W. Zhu

    2003-01-01

    The electrochemical behavior of a carboxyl-modified carbon nanotube films was investigated to explore its possibility in electroanalytical applicaton. Cyclic voltammetry of quinone was conducted in 1mol/L Na2SO4, which showed a stable, quasi-reversible voltammetric response for quinone / hydroquinone, and the anodic and the cathodic peak potentials were 0.657V and -0.029V (vs. SCE) at a scan rate of 0.1V.s-1, respectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.01-0. 5 V.s-1, which suggested that the process of the electrode reactions was diffusion-controlled. Carboxyl-modified carbon nanotube electrodes made it possible to determine low level of dopamine selectively in the presence of a large excess of ascorbic acid in acidic media using derivative voltammetry.The results obtained were discussed in details. This work demonstrates the potential of carboxyl-modified carbon nanotube electrodes for electroanalytical applications.

  8. Investigation of bioresistant dry building mixes modified by carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Korolev Evgeniy Valer'evich

    2015-04-01

    Full Text Available Dry construction mixes are today a product of high technologies. Depending on the purpose and requirements to the properties it is easy to produce dry construction mixes with different compositions and operating indicators in plant conditions using the necessary modifying additives. Cement, gypsum and other mineral binders are used in the construction mixes. Different types of cement are more heavily used in dry construction mixes. Such dry mixes are believed to be more effective materials comparing to traditional cement-sandy solutions of centralized preparation. The authors present the results of the investigations on obtaining biocidal cement-sand compositions. It was established, that introduction of sodium sulfate into the composition provides obtaining the materials with funginert and fungicide properties. The strength properties of the mixes modified by carbon nanotubes and biocide additive were investigated by mathematical planning methods. The results of the investigations showed that the modification of cement stone structure by carbon nanotubes positively influences their strength and technological properties. Nanomodifying of construction composites by introducing carbon nanotubes may be effectively used at different stages of structure formation of a construction material.

  9. Carbon nanoparticle-modified multi-wall carbon nanotubes with fast adsorption kinetics for water treatment

    Science.gov (United States)

    Wang, Guan; Ren, Wei; Tan, Hui Ru; Liu, Ye

    2017-02-01

    Carbon nanoparticle-modified multi-wall carbon nanotubes were prepared using a dehydration of carbohydrate compound method. The structural change was characterized by transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett and Teller measurement. Fast adsorption kinetics was observed for multi-wall carbon nanotubes with modification, as demonstrated by the adsorption of the model compound methylene blue. This work provides a novel facile engineering strategy to equip multi-wall carbon nanotubes with fast adsorption kinetics, which is promising for efficient water purification.

  10. Voltammetric Response of Epinephrine at Carbon Nanotube Modified Glassy Carbon Electrode and Activated Glassy Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    WANG Juan; TANG Ping; ZHAO Fa-qiong; ZENG Bai-zhao

    2005-01-01

    The electrochemical behavior of epinephrine at activated glassy carbon electrode and carbon nanotube-coated glassy carbon electrode was studied. Epinephrine could exhibit an anodic peak at about 0.2 V (vs. SCE) at bare glassy carbon electrode, but it was very small.However, when the electrode was activated at certain potential (i. e. 1.9V) or modified with carbon nanotube, the peak became more sensitive,resulting from the increase in electrode area in addition to the electrostatic attraction. Under the selected conditions, the anodic peak current was linear to epinephrine concentration in the range of 3.3 × 10-7-1.1 × 10-5mol/L at activated glassy carbon electrode and in the range of 1.0 × 10-6-5.0 × 10-5 mol/L at carbon nanotube-coated electrode. The correlation coefficients were 0. 998 and 0. 997, respectively. The determination limit was 1.0 × 10-7 mol/L. The two electrodes have been successfully applied for the determination of epinephrine in adrenaline hydrochloride injection with recovery of 95%-104%.

  11. Electrical Resistance and Magnetoresistance of Modified Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    T.A. Len

    2014-11-01

    Full Text Available The paper presents the results of the experimental studies of the magnetoresistance and electrical resistance of carbon nanotubes modified with iron and iron oxide. A comprehensive study of the processes, which act with change in the temperature of modified CNTs, is performed. Joint analysis of the structural studies and electrical transport characteristics is enabled to explain new and interesting results. It is established that modification with iron has little effect on the electrical resistance. On the other hand, modification is strongly reflected on the ferromagnetic resistance anisotropy. It is shown that the localization mechanism and anisotropic magnetoresistance are manifested in magnetoresistance. Anisotropic magnetoresistance arises due to the features of magnetization of ferromagnetic phase in an external magnetic field.

  12. Preparation and Characterization of Polycarbonate Modified Multiple-walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    YU Jin-Gang; HUANG Ke-Long; LIU Su-Qin; TANG Jin-Chun

    2008-01-01

    To prepare polymer/carbon nanotube composites, polycarbonate was chosen to modify multiple-walled carbon nanotubes. Poly[(propylene oxide)-(carbon dioxide)-(ε-caprolactone)], poly(butylene-co-ε-caprolactone carbonate),and poly[(propylene oxide)-co-(carbon dioxide)-co-(maleic anhydride)] were the polycarbonates which were used to modify multiple-walled carbon nanotubes, but only soluble poly[(propylene oxide)-(carbon dioxide)-(ε-caprolactone)] modified multiple-walled carbon nanotubes could be obtained. Thermogravimetric analysis clearly indicated that more polycarbonates were attached to soluble poly[(propylene oxide)-(carbon dioxide)-(ε-caprolactone)] modified multiple-walled carbon nanotubes. The formation of surface functional groups and changes of nanotube structures and morphology were monitored by infrared spectroscopy, scanning electron microscopy and transmission electron microscopy, respectively. Because of their solubility and bioactive moieties,poly[(propylene oxide)-(carbon dioxide)-(ε-caprolactone)] modified multiple-walled carbon nanotubes may find their potential use in drug delivery.

  13. Reprogramming cellular signaling machinery using surface-modified carbon nanotubes.

    Science.gov (United States)

    Zhang, Yi; Wu, Ling; Jiang, Cuijuan; Yan, Bing

    2015-03-16

    Nanoparticles, such as carbon nanotubes (CNTs), interact with cells and are easily internalized, causing various perturbations to cell functions. The mechanisms involved in such perturbations are investigated by a systematic approach that utilizes modified CNTs and various chemical-biological assays. Three modes of actions are (1) CNTs bind to different cell surface receptors and perturb different cell signaling pathways; (2) CNTs bind to a receptor with different affinity and, therefore, strengthen or weaken signals; (3) CNTs enter cells and bind to soluble signaling proteins involved in a signaling pathway. Understanding of such mechanisms not only clarifies how CNTs cause cytotoxicity but also demonstrates a useful method to modulate biological/toxicological activities of CNTs for their various industrial, biomedical, and consumer applications.

  14. Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

    2011-02-01

    An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

  15. Strain-modified RKKY interaction in carbon nanotubes

    DEFF Research Database (Denmark)

    Gorman, P. D.; Duffy, J. M.; Power, Stephen R.

    2015-01-01

    For low-dimensionalmetallic structures, such as nanotubes, the exchange coupling between localized magnetic dopants is predicted to decay slowly with separation. The long-range character of this interaction plays a significant role in determining the magnetic order of the system. It has previously...... been shown that the interaction range depends on the conformation of the magnetic dopants in both graphene and nanotubes. Here we examine the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in carbon nanotubes in the presence of uniaxial strain for a range of different impurity configurations. We show...... that strain is capable of amplifying or attenuating the RKKY interaction, significantly increasing certain interaction ranges, and acting as a switch: effectively turning on or off the interaction. We argue that uniaxial strain can be employed to significantly manipulate magnetic interactions in carbon...

  16. Direct Electrochemistry of Catalase on Single Wall Carbon Nanotubes Modified Glassy Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    Qiang ZHAO; Lun Hui GUAN; Zhen Nan GU; Qian Kun ZHUANG

    2005-01-01

    Direct electrochemistry of catalase (Ct) has been studied on single wall carbon nanotubes (SWNTs) modified glassy carbon (GC) electrode. A pair of well-defined nearly reversible redox peaks is given at --0.48 V (vs. SCE) in 0.1 mol/L phosphate solution (pH 7.0).The peak current in cyclic voltammogram is proportional to the scan rate. The peak potential of catalase is shifted to more negative value when the pH increases. Catalase can adsorb on the SWNTs modified electrode.

  17. Hall Measurements on Carbon Nanotube Paper Modified With Electroless Deposited Platinum

    Directory of Open Access Journals (Sweden)

    Iwuoha Emmanuel

    2009-01-01

    Full Text Available Abstract Carbon nanotube paper, sometimes referred to as bucky paper, is a random arrangement of carbon nanotubes meshed into a single robust structure, which can be manipulated with relative ease. Multi-walled carbon nanotubes were used to make the nanotube paper, and were subsequently modified with platinum using an electroless deposition method based on substrate enhanced electroless deposition. This involves the use of a sacrificial metal substrate that undergoes electro-dissolution while the platinum metal deposits out of solution onto the nanotube paper via a galvanic displacement reaction. The samples were characterized using SEM/EDS, and Hall-effect measurements. The SEM/EDS analysis clearly revealed deposits of platinum (Pt distributed over the nanotube paper surface, and the qualitative elemental analysis revealed co-deposition of other elements from the metal substrates used. When stainless steel was used as sacrificial metal a large degree of Pt contamination with various other metals was observed. Whereas when pure sacrificial metals were used bimetallic Pt clusters resulted. The co-deposition of a bimetallic system upon carbon nanotubes was a function of the metal type and the time of exposure. Hall-effect measurements revealed some interesting fluctuations in sheet carrier density and the dominant carrier switched from N- to P-type when Pt was deposited onto the nanotube paper. Perspectives on the use of the nanotube paper as a replacement to traditional carbon cloth in water electrolysis systems are also discussed.

  18. Hall measurements on carbon nanotube paper modified with electroless deposited platinum.

    Science.gov (United States)

    Petrik, Leslie; Ndungu, Patrick; Iwuoha, Emmanuel

    2009-09-18

    Carbon nanotube paper, sometimes referred to as bucky paper, is a random arrangement of carbon nanotubes meshed into a single robust structure, which can be manipulated with relative ease. Multi-walled carbon nanotubes were used to make the nanotube paper, and were subsequently modified with platinum using an electroless deposition method based on substrate enhanced electroless deposition. This involves the use of a sacrificial metal substrate that undergoes electro-dissolution while the platinum metal deposits out of solution onto the nanotube paper via a galvanic displacement reaction. The samples were characterized using SEM/EDS, and Hall-effect measurements. The SEM/EDS analysis clearly revealed deposits of platinum (Pt) distributed over the nanotube paper surface, and the qualitative elemental analysis revealed co-deposition of other elements from the metal substrates used. When stainless steel was used as sacrificial metal a large degree of Pt contamination with various other metals was observed. Whereas when pure sacrificial metals were used bimetallic Pt clusters resulted. The co-deposition of a bimetallic system upon carbon nanotubes was a function of the metal type and the time of exposure. Hall-effect measurements revealed some interesting fluctuations in sheet carrier density and the dominant carrier switched from N- to P-type when Pt was deposited onto the nanotube paper. Perspectives on the use of the nanotube paper as a replacement to traditional carbon cloth in water electrolysis systems are also discussed.

  19. A Multiwall Carbon Nanotube-chitosan Modified Electrode for Selective Detection of Dopamine in the Presence of Ascorbic Acid

    Institute of Scientific and Technical Information of China (English)

    Ling Yan JIANG; Chuan Yin LIU; Li Ping JIANG; Guang Han LU

    2005-01-01

    A novel multiwall carbon nanotube-chitosan modified electrode has been prepared.The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peak by 212 mY. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine can be determined selectively with the carbon nanotube-chitosan modified electrode. The electrode shows good sensitivity, selectivity and stability.keywords: Nanotube-chitosan modified electrode, dopamine, ascorbic acid.

  20. Carbon Nanotube Coating on Titanium Substrate Modified with TiO2 Nanotubes

    Institute of Scientific and Technical Information of China (English)

    BAI Yu; PARK Ilsong; BAE Taesung; KLM Kyounga; WATARI Fumio; UO Motohiro; LEE Minho

    2011-01-01

    A combination of carbon nanotubes (CNTs) and titanium (Ti) modified with TiO2 nanotubes (TiO2 NTs) was fulfilled with the aim of improving bioactivity of Ti implant.First,well-ordered TiO2 NTs were prepared by the electrochemical anodization of Ti in an ethylene glycol electrolyte containing 1 wt% NH4F and 10 wt% H2O at 20 V for 50 min,followed by annealing.Then,the carboxylated CNTs were coated onto the TiO2NTs using electrophoretic deposition (EPD) technique.The growth of hydroxyapatite (HA) on the samples was investigated by soaking them in simulated body fiuid (SBF).The result showed the CNTs-coated Ti with the modification of TiO2 NTs (CNTs-TiO2 NTs) was more efficient to induce HA formation than the CNTs-coated smooth Ti (CNTs-Ti).The vitro cell response was evaluated using osteoblast cells (MC3T3-El).The good cell proliferation and strong cell adhesion could be obtained on the CNTs-TiO2 NTs.These results indicated that CNT coating on the Ti modified with TiO2 NTs could be potentially useful for the periodontal ligament combination on dental implants.

  1. A study of single-walled carbon nanotubes modified by organics of the phthalocyanine category

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Organics of the phthalocyanine category have very good nonlinear optical properties. The single-walled carbon nanotubes were modified by using the phenoxy phthalocyanine. Characterization analysis was made by means of the transmission electron microscope (TEM), ultraviolet visible absorptive spectra, fluorescent spectra and Raman spectra. Under the TEM, it was observed that the composite looked like sugarcoated haws. By comparing the ultraviolet visible absorptive spectra before and after absorption, it was disclosed that the spectral intensity and the intensity of the peaks in the fluorescent spectra dropped remarkably. This shows that the single-walled carbon nanotubes have absorbed a large number of phenoxy phthalocyanines. Raman analysis revealed that in the Raman spectra, the position of the main peaks of the single-walled carbon nanotubes after absorption moved in the direction of long waves. The analysis suggests that the movement of the Raman spectra results from the change in the state of the single-walled carbon nanotubes before and after absorption.

  2. Carbon nanotube-nucleobase hybrids: nanorings from uracil-modified single-walled carbon nanotubes.

    Science.gov (United States)

    Singh, Prabhpreet; Toma, Francesca Maria; Kumar, Jitendra; Venkatesh, V; Raya, Jesus; Prato, Maurizio; Verma, Sandeep; Bianco, Alberto

    2011-06-06

    Single-walled carbon nanotubes (SWCNTs) have been covalently functionalized with uracil nucleobase. The hybrids have been characterized by using complementary spectroscopic and microscopic techniques including solid-state NMR spectroscopy. The uracil-functionalized SWCNTs are able to self-assemble into regular nanorings with a diameter of 50-70 nm, as observed by AFM and TEM. AFM shows that the rings do not have a consistent height and thickness, which indicates that they may be formed by separate bundles of CNTs. The simplest model for the nanoring formation likely involves two bundles of CNTs interacting with each other via uracil-uracil base-pairing at both CNT ends. These nanorings can be envisaged for the development of advanced electronic circuits.

  3. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Huiying Wang

    2013-11-01

    Full Text Available A versatile strategy for electrochemical determination of glycoalkaloids (GAs was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

  4. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    Science.gov (United States)

    Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

    2013-01-01

    A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors. PMID:24287539

  5. Linear polymer separation using carbon-nanotube-modified centrifugal filter units.

    Science.gov (United States)

    Krawczyk, Tomasz; Marian, Karolina; Pawlyta, Mirosława

    2016-02-01

    The separation of linear polymers such as polysaccharides and polyethylene glycol was performed with modified commercial centrifugal filter units. The deposition of a 0.16-0.35 μm layer of modified carbon nanotubes prevented permeation of linear polymers of molecular weight higher than 20 000 Da through the membrane. It allowed facile purification of solution of 0.1 g of polymer samples from small molecules within 25 min by using a bench-top centrifuge. The structure of modified carbon nanotubes was optimized in order to achieve good adhesion to the low binding regenerated cellulose surface and low solubility in aqueous solutions after deposition. The best modification of carbon nanotubes was oxidation and subsequent amide formation of diethanolamine. Introduction of acetic acid groups using sodium chloroacetate worked equally well. The modified filter could be used multiple times without the decrease of the efficiency. The carbon nanotubes layer was stable in aqueous solutions in a pH range of 1-7. The proposed method provides a convenient way of purification of modified polymers in research areas such as drug delivery or macromolecular probes synthesis.

  6. Design of Dendrimer Modified Carbon Nanotubes for Gene Delivery

    Institute of Scientific and Technical Information of China (English)

    PAN Bi-feng; BAO Chen-chen; GAO Feng; HE Rong; SHU Meng-jun; MA Yong-jie; CUI Da-xiang; XU Ping; CHEN Hao; LIU Feng-tao; LI Qing; HUANG Tuo; YOU Xiao-gang; SHAO Jun

    2007-01-01

    Objective: To investigate the efficiency of polyamidoamine dendrimer grafted carbon nanotube (dendrimer-CNT) mediated entrance of anti-survivin oligonucleotide into MCF-7 cells, and its effects on the growth of MCF-7 cells. Methods: Antisense survivin oligonucleotide was anchored onto polyamidoamine dendrimer grafted carbon nanotubes to form dendrimer-CNT-asODN complex and the complex was characterized by Zeta potential, AFM, TEM, and 1% agarose gel electrophoresis analysis. Dendrimer-CNT-asODN complexes were added into the medium and incubated with MCF-7 cells. MTT method was used to detect the effects of asODN and dendrimer-CNT-asODN on the growth of MCF-7 cells. TEM was used to observe the distribution of dendrimer-CNT-asODN complex within MCF-7 cells. Results: Successful synthesis of dendrimer-CNT-asODN complexes was proved by TEM, AFM and agarose gel electrophoresis. TEM showed that the complexes were located in the cytoplasm, endosome, and lysosome within MCF-7 cells. When dendrimer-CNT-asODN (1.0 μmol/L) and asODN (1.0 μmol/L) were used for 120 h incubation, the inhibitory rates of MCF-7 cells were (28.22±3.5)% for dendrimer-CNT-asODN complex group, (9.23±0.56)% for only asODN group, and (3.44±0.25)% for dendrimer-CNT group. Dendrimer-CNT-asODN complex at 3.0 μmol/L inhibited MCF-7 cells by (30.30±10.62)%, and the inhibitory effects were in a time- and concentration- dependent manner. Conclusion: Dendrimer-CNT nanoparticles may serve as a gene delivery vector with high efficiency, which can bring foreign gene into cancer cells, inhibiting cancer cell proliferation and markedly enhancing the cancer therapy effects.

  7. Organic modification of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The organic modification of carbon nanotubes is a novel research field being developed recently. In this article, the history and newest progress of organic modification of carbon nanotubes are reviewed from two aspects:organic covalent modification and organic noncovalent modification of carbon nanotubes. The preparation and properties of organic modified carbon nanotubes are discussed in detail. In addition, the prospective development of organic modification of carbon nanotubes is suggested.

  8. Novel estradiol sensors based on carbon nanotube multilayer modified gold hair microelectrodes

    Institute of Scientific and Technical Information of China (English)

    Jun Hui Xu; Cheng Guo Hu; Sheng Shui Hu

    2009-01-01

    Multi-walled carbon nanotube multilayers were modified onto a newly proposed gold hair microelectrode via a simple layer-by-layer assembling method. The resulting electrode showed a sensitive oxidation response to estradiol with detection limit as low as 1.0×10~(-8) mol/L, foreseeing a promising approach to the fabrication of high-sensitive microsensors.

  9. Thermal desorption of deuterium from modified carbon nanotubes and its correlation to the microstructure

    NARCIS (Netherlands)

    Lisowski, W.; Keim, E.G.; Berg, van den A.H.J.; Smithers, M.A.

    2006-01-01

    The process of deuterium desorption from single-wall carbon nanotubes (SWNTs) modified by atomic (D) and molecular (D2) deuterium treatment was investigated in an ultrahigh vacuum environment using thermal desorption mass spectroscopy (TDMS). Microstructural and chemical analyses of SWNT material, m

  10. Improvement of the LiBH{sub 4} hydrogen desorption by confinement in modified carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.T.; Wan, C.B.; Meng, X.H.; Ju, X., E-mail: jux@ustb.edu.cn

    2015-10-05

    Highlights: • The desorption kinetics for LiBH{sub 4} greatly promoted using melt infiltration method. • The LiBH{sub 4} confined in modified MWCNTs shows the best desorption kinetics. • The crystal structure of MWCNTs and SWCNTs is unchanged after ball milling. • Ball milling introduces a great amount of structural defects in the CNTs. • Nano-confinement is dominant on improving the hydrogen desorption of LiBH{sub 4}. - Abstract: The dehydrogenation kinetics of LiBH{sub 4} incorporated within various carbon nanotubes has been studied. It is demonstrated that the desorption kinetics of LiBH{sub 4} could be greatly promoted using a simple melt infiltration method and LiBH{sub 4} confined in modified multi-walled carbon nanotubes (MWCNTs) shows the best desorption kinetics. The structural properties of carbon nanotubes and confined samples are demonstrated by means of transmission electron microscopy, powder X-ray diffraction and Raman spectroscopy. The crystal structure of MWCNTs and single-walled carbon nanotubes (SWCNTs) are almost unchanged after ball milling. But high energy ball milling leads to a decrease in the average nanotube length and introduces a great amount of local disorder and structural defects in the CNTs, which may provide a considerable kinetic improvement.

  11. A carbon monoxide gas sensor using oxygen plasma modified carbon nanotubes

    Science.gov (United States)

    Zhao, Weiyun; Fam, Derrick Wen Hui; Yin, Zongyou; Sun, Ting; Tan, Hui Teng; Liu, Weiling; Iing Yoong Tok, Alfred; Boey, Yin Chiang Freddy; Zhang, Hua; Hng, Huey Hoon; Yan, Qingyu

    2012-10-01

    Carbon monoxide (CO) is a highly toxic gas that can be commonly found in many places. However, it is not easily detected by human olfaction due to its colorless and odorless nature. Therefore, highly sensitive sensors need to be developed for this purpose. Carbon nanotubes (CNTs) have an immense potential in gas sensing. However, CNT-based gas sensors for sensing CO are seldom reported due to the lack of reactivity between CO and CNTs. In this work, O2 plasma modified CNT was used to fabricate a CNT gas sensor. The plasma treated CNTs showed selectively towards CO, with the capability of sensing low concentrations of CO (5 ppm) at room temperature, while the pristine CNTs showed no response. UV spectra and oxygen reduction reaction provided evidence that the difference in sensing property was due to the elimination of metallic CNTs and enhancement of the oxygen reduction property.

  12. Electrooxidation of DNA at glassy carbon electrodes modified with multiwall carbon nanotubes dispersed in polyethylenimine

    Energy Technology Data Exchange (ETDEWEB)

    Luque, Guillermina L.; Ferreyra, Nancy F. [INFIQC, Departamento de Fisico Quimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Granero, Adrian [INFIQC, Departamento de Fisico Quimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Departamento de Quimica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Rio Cuarto (Argentina); Bollo, Soledad [Laboratorio de Bioelectroquimica, Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile, P.O. Box 233, Santiago (Chile); Rivas, Gustavo A., E-mail: grivas@fcq.unc.edu.ar [INFIQC, Departamento de Fisico Quimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2011-10-30

    This work reports the electrochemical response of the complex between dsDNA and PEI formed in solution and at the surface of glassy carbon electrodes (GCE) modified with a dispersion of multi-walled carbon nanotubes in polyethylenimine (CNT-PEI). Scanning Electron Microscopy and Scanning Electrochemical Microscopy demonstrate that the dispersion covers the whole surface of the electrode although there are areas with higher density of CNT and, consequently, with higher electrochemical reactivity. The adsorption of DNA at GCE/CNT-PEI is fast and it is mainly driven by electrostatic forces. A clear oxidation signal is obtained either for dsDNA or a heterooligonucleotide of 21 bases (oligoY) at potentials smaller than those for the oxidation at bare GCE. The comparison of the behavior of DNA before and after thermal treatment demonstrated that the electrochemical response highly depends on the 3D structure of the nucleic acid.

  13. Surface characteristics of modified carbon nanotubes and its application in lead adsorption from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Carbon nanotubes (CNT) were modified by nitric acid oxidation. Infrared spectroscopy (IR) demonstrated that hydroxyl (-OH) and carbonyl (-C== O) functional groups were introduced to the surface of modified CNT. Micrometrics ASAP 2000 measurement showed that the surface area of modified CNT was slightly increased. Furthermore, the Pb2+ adsorption behavior on the surface of modified CNT has been investigated. The results indicate that the modified CNT has an exceptional adsorption capability for Pb2+ removal. The adsorption isotherms are well described by the Langmuir equation under test temperatures and the kinetics level is three.

  14. Electroanalysis of some common pesticides using conducting polymer/multiwalled carbon nanotubes modified glassy carbon electrode.

    Science.gov (United States)

    Manisankar, P; Sundari, Pl Abirama; Sasikumar, R; Palaniappan, Sp

    2008-09-15

    The cyclic voltammetric behaviour of three common pesticides such as isoproturon (ISO), voltage (VOL) and dicofol (DCF) was investigated at glassy carbon electrode (GCE), multiwalled carbon nanotubes modified GCE (MWCNTs/GCE), polyaniline (PANI) and polypyrrole (PPY) deposited MWCNT/GCE. The modified electrode film was characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The electroactive behaviour of the pesticides was realized from the cyclic voltammetric studies. The differential pulse voltammetric principle was used to analyze the above-mentioned pesticides using MWCNT/GCE, PANI/MWCNT/GCE and PPY/MWCNT/GCE. Effects of accumulation potential, accumulation time, Initial scan potential, amplitude and pulse width were examined for the optimization of stripping conditions. The PANI/MWCNT/GCE performed well among the three electrode systems and the determination range obtained was 0.01-100 mgL(-1) for ISO, VOL and DCF respectively. The limit of detection (LOD) was 0.1 microgL(-1) for ISO, 0.01 microgL(-1) for VOL and 0.05 microgL(-1) for DCF on PANI/MWCNT/GCE modified system. It is significant to note that the PANI/MWCNT/GCE modified system results in the lowest LOD in comparison with the earlier reports. Suitability of this method for the trace determination of pesticide in spiked samples was also realized.

  15. Removal of Chromium (III from Water by Using Modified and Nonmodified Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Muataz Ali Atieh

    2010-01-01

    Full Text Available This study was carried out to evaluate the environmental application of modified and nonmodified carbon nanotubes through the experiment removal of chromium trivalent (III from water. The aim was to find the optimal condition of the chromium (III removal from water under different treatment conditions of pH, adsorbent dosage, contact time and agitation speed. Multi wall carbon nanotubes (MW-CNTs were characterized by field emission scanning electron microscopy (FE-SEM and transmission electron microscopy (TEM. The diameter of the carbon nanotubes produced varied from 20–40 nm with average diameter of 24 nm and 10 micrometer in length. Adsorption isotherms were used to model the adsorption behavior and to calculate the adsorption capacity of the absorbents. The results showed that, 18% of chromium (III removal was achieved using modified carbon nanotubes (M-CNTs at pH 7, 150 rpm, and 2 hours for a dosage of 150 mg of CNTs. The removal of Cr (III is mainly attributed to the affinity of chromium (III to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

  16. Electrochemical capacitor improvement fabricated by carbon microfiber composite with admicellar-modified carbon nanotube

    Science.gov (United States)

    Pongprayoon, Thirawudh; Ayutthaya, Montira Seneewong-Na; Poochai, Chatwarin

    2017-02-01

    Conventional electrochemical capacitors are usually made from activated carbon microfiber electrode, which has relatively low electrochemical capacitance. To improve performance of electrochemical capacitor, carbon nanotube (CNT) was used to incorporate in carbon microfiber. Firstly, CNT was coated with ultra-thin polyacrylonitrile (PAN) film coating using the admicellar polymerization technique to improve its dispersion in PAN matrix. Secondly, the mix solution of admicellar-modified CNT (Ad-CNT) and PAN in N,N-dimethylformamide (DMF) was prepared to produce microfiber by electrospinning. Lastly, microfiber was collected as a sheet, which was then stabilized and carbonized to be used as an electrode. The fabricated electrode using Ad-CNT/PAN was analyzed by SEM and TEM. SEM images show that the microfiber was uniform with approximately 2 μm average diameter. TEM images display well alignment and good dispersion of Ad-CNT in the matrix. The electrode made from Ad-CNT/PAN exhibited a high specific capacitance of 125 F g-1 at a scan rate of 3 mV s-1 (based on cyclic voltammetry) and 82 F g-1 at a specific current of 1 A g-1 (based on galvanostatic charge/discharge). The percentage of relative specific capacitance retention of the prepared electrode was 70% after 1000 cycles. The results clearly show that the Ad-CNT played an effective role in improving dispersion in electrode leading to increase in electrical conductivity as well as electrical capacitance of the capacitor.

  17. Enhanced Growth and Redox Characteristics of Some Conducting Polymers on Carbon Nanotube Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    R.Saraswathi

    2007-01-01

    1 Results Recent studies on the electrochemistry of a number of active compounds at carbon nanotube electrodes have proved beyond doubt their excellent electrocatalytic properties.Particularly,the advancements accomplished towards the functionalization of carbon nanotubes resulting in their enhanced solubilization in aqueous solutions have helped in the preparation of stable carbon nanotube electrodes.Glassy carbon has been invariably the preferred substrate for casting carbon nanotube electrodes.Such c...

  18. Electrocatalytic oxidation of deferiprone and its determination on a carbon nanotube-modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yadegari, H. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Karimian, K. [Arasto Pharmaceutical Chemicals Inc., Tehran (Iran, Islamic Republic of); Khodadadi, A. [Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2008-02-15

    The electrochemical behavior of the anti-thalassemia and anti-HIV replication drug, deferiprone, was investigated on a carbon nanotube-modified glassy carbon (GC-CNT) electrode in phosphate buffer solution, pH 7.40 (PBS). During oxidation of deferiprone, two irreversible anodic peaks, with E{sub 1}{sup 0}=452 and E{sub 2}{sup 0}=906mV, appeared, using GC-CNT. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that deferiprone is oxidized via two two-electron steps. The results revealed that carbon nanotube (CNT) promotes the rate of oxidation by increasing the peak current, so that deferiprone is oxidized at lower potentials, which thermodynamically is more favorable. This result was confirmed by impedance measurements. The diffusion coefficient, electron-transfer coefficient and heterogeneous electron-transfer rate constant of deferiprone were found to be 1.49 x 10{sup -6} cm{sup 2} s{sup -1}, 0.44, and 3.83 x 10{sup -3} cm s{sup -1}, respectively. A sensitive, simple and time-saving differential-pulse voltammetric procedure was developed for the analysis of deferiprone. Using the proposed method, deferiprone can be determined with a detection limit of 5.25 x 10{sup -7} M. The applicability of the method to direct assays of spiked human serum and urine fluids is described.

  19. Synthesization of SnO2-modified carbon nanotubes and their application in microbial fuel cell

    Science.gov (United States)

    Wang, Zi-Bo; Xiong, Shi-Chang; Guan, Yu-Jiang; Zhu, Xue-Qiang

    2016-03-01

    The aim of this work was to study the synthesization of SnO2-modified carbon nanotubes and their application in microbial fuel cell. With the chemical vapor deposition technique, carbon nanotubes growing in situ on a carbon felt are obtained. A SnO2 sol was applied to the carbon felt to prepare a SnO2-modified carbon nanotubes. X-ray diffraction and energy-dispersive X-ray analysis confirmed that SnO2 existed in the prepared samples. Using the prepared samples as anode electrodes, flexible graphite as cathode, and glucose solution as substrate in microbial fuel cell, the effects of the temperature, substrate concentration, and electrodes on removal rates for chemical oxygen demand and the performance of microbial fuel cell have been analyzed. With substrate concentration of 1500 mg L-1, the microbial fuel cell had an optimal output voltage of 563 mV and a removal rate of 78 % for chemical oxygen demand at 311 K. The composite electrodes are stable and reusable.

  20. Microstructure and mechanical performance of modified mortar using hemp fibres and carbon nanotubes

    KAUST Repository

    Hamzaoui, Rabah

    2014-04-01

    Mechanical performance of modified mortar using hemp fibres is studied following various processing conditions. Hemp fibres combined with carbon nanotubes (CNT) are introduced in mortar and their effect is studied as function of curing time. The cement phase is replaced by different percentages of dry or wet hemp fibres ranging from 1.1. wt% up to 3.1. wt% whereas carbon nanotubes are dispersed in the aqueous solution. Our experimental results show that compressive and flexural strengths of wet fibres modified mortar are higher than those for dry hemp-mortar material. The achieved optimal percentage of wet hemp fibres is 2.1. wt% allowing a flexural strength higher than that of reference mortar. The addition of an optimal CNT concentration (0.01. wt%) combined with wet hemp has a reinforcing effect which turns to be related to an improvement of compressive and flexural strengths by 10% and 24%, respectively, in comparison with reference condition. © 2013 Elsevier Ltd.

  1. Electrochemical investigation of NO at single-wall carbon nanotubes modified electrodes

    Indian Academy of Sciences (India)

    Tingliang Xia; Hongmei Bi; Keying Shi

    2010-05-01

    The NO electro-oxidation was investigated at various single-wall carbon nanotubes (SWCNTs) modified electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the glassy carbon electrode, the SWCNTs modified electrodes possess higher electro-catalytic activity to NO electro-oxidation. CV results indicate that the peak current density of NO electro-oxidation at the SWCNT-COOH (SWCNTs with carboxyl groups) modified electrode is the highest and the peak potential is the most negative among the four kinds of electrodes. EIS indicates that the charge transfer resistance of NO electro-oxidation at the SWCNT-COOH modified electrode is the least. The determined factors (charge transfer and mass transfer of diffusion) of NO electro-oxidation are different in varied potential region. The mechanism of NO electro-oxidation reaction at the SWCNTs modified electrodes is also discussed.

  2. A Novel Cholesterol Oxidase Biosensor Based on Pt-nanoparticle /Carbon Nanotube Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    Qiao Cui SHI; Tu Zhi PENG

    2005-01-01

    A Pt-nanoparticle/carbon nanotube modified graphite electrode immobilized with cholesterol oxidase/sol-gel layer was developed for monitoring cholesterol. Using this electrode,cholesterol concentration (4.0×10-6 to 1.0×10 mol/L) could be determined accurately in the presence of ascorbic or uric acid, and the response time was rapid (< 20 s). This biosensor has high sensitivity and selectivity.

  3. A study of single-walled carbon nanotubes modified by organics of the phthalocyanine category

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Organics of the phthalocyanine category have very good nonlinear optical properties. The single-walled carbon nanotubes were modified by using the phenoxy phthalocyanine. Characterization analysis was made by means of the transmission electron microscope (TEM), ultraviolet visible absorptive spectra, fluorescent spectra and Raman spectra. Under the TEM, it was observed that the composite looked like sugarcoated haws. By comparing the ultraviolet visible absorptive spectra before and after absorption, it was...

  4. Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jessica E. [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Pillai, Shreekumar [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States); Ram, Manoj Kumar, E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Singh, Shree R. [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States)

    2011-07-20

    Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

  5. Hydrogen storage: a comparison of hydrogen uptake values in carbon nanotubes and modified charcoals

    Science.gov (United States)

    Miao, H.-Y.; Chen, G. R.; Chen, D. Y.; Lue, J. T.; Yu, M. S.

    2010-11-01

    We compared the hydrogen uptake weight percentages (wt.%) of different carbonized materials, before and after modification, for their application in hydrogen storage at room temperature. The Sievert's method [T.P. Blach, E. Mac, A. Gray, J. Alloys Compd. 446-447, 692 (2007)] was used to measure hydrogen uptake values on: (1) Taiwan bamboo charcoal (TBC), (2) white charcoal (WC), (3) single-walled carbon nanotubes (SWCNTs) bought from CBT Inc. and (4) homemade multi-walled carbon nanotubes (MWCNTs) grown on TBC. Modified samples were coated with a metal catalyst by dipping in KOH solutions of different concentrations and then activated in a high temperature oven (800 °C) under the atmospheric pressure of inert gas. The results showed that unmodified SWCNTs had superior uptake but that Taiwan bamboo charcoal, after modification, showed enhanced uptake comparable to the SWCNTs. Due to TBC's low cost and high mass production rate, they will be the key candidate for future hydrogen storage applications.

  6. Electrocatalytic Study of Paracetamol at a Single-Walled Carbon Nanotube/Nickel Nanocomposite Modified Glassy Carbon Electrode

    OpenAIRE

    Koh Sing Ngai; Wee Tee Tan; Zulkarnain Zainal; Ruzniza Mohd Zawawi; Joon Ching Juan

    2015-01-01

    A rapid, simple, and sensitive method for the electrochemical determination of paracetamol was developed. A single-walled carbon nanotube/nickel (SWCNT/Ni) nanocomposite was prepared and immobilized on a glassy carbon electrode (GCE) surface via mechanical attachment. This paper reports the voltammetry study on the effect of paracetamol concentration, scan rate, pH, and temperature at a SWCNT/Ni-modified electrode in the determination of paracetamol. The characterization of the SWCNT/Ni/GCE w...

  7. Modifying the electronic properties of single-walled carbon nanotubes using designed surfactant peptides.

    Science.gov (United States)

    Samarajeewa, Dinushi R; Dieckmann, Gregg R; Nielsen, Steven O; Musselman, Inga H

    2012-08-07

    The electronic properties of carbon nanotubes can be altered significantly by modifying the nanotube surface. In this study, single-walled carbon nanotubes (SWCNTs) were functionalized noncovalently using designed surfactant peptides, and the resultant SWCNT electronic properties were investigated. These peptides have a common amino acid sequence of X(Valine)(5)(Lysine)(2), where X indicates an aromatic amino acid containing either an electron-donating or electron-withdrawing functional group (i.e. p-amino-phenylalanine or p-cyano-phenylalanine). Circular dichroism spectra showed that the surfactant peptides primarily have random coil structures in an aqueous medium, both alone and in the presence of SWCNTs, simplifying analysis of the peptide/SWCNT interaction. The ability of the surfactant peptides to disperse individual SWCNTs in solution was verified using atomic force microscopy and ultraviolet-visible-near-infrared spectroscopy. The electronic properties of the surfactant peptide/SWCNT composites were examined using the observed nanotube Raman tangential band shifts and the observed additional features near the Fermi level in the scanning tunneling spectroscopy dI/dV spectra. The results revealed that SWCNTs functionalized with surfactant peptides containing electron-donor or electron-acceptor functional groups showed n-doped or p-doped altered electronic properties, respectively. This work unveils a facile and versatile approach to modify the intrinsic electronic properties of SWCNTs using a simple peptide structure, which is easily adaptable to obtain peptide/SWCNT composites for the design of tunable nanoscale electronic devices.

  8. Synthesis, pharmacokinetics, and biological use of lysine-modified single-walled carbon nanotubes.

    Science.gov (United States)

    Mulvey, J Justin; Feinberg, Evan N; Alidori, Simone; McDevitt, Michael R; Heller, Daniel A; Scheinberg, David A

    2014-01-01

    We aimed to create a more robust and more accessible standard for amine-modifying single-walled carbon nanotubes (SWCNTs). A 1,3-cycloaddition was developed using an azomethine ylide, generated by reacting paraformaldehyde and a side-chain-Boc (tert-Butyloxycarbonyl)-protected, lysine-derived alpha-amino acid, H-Lys(Boc)-OH, with purified SWCNT or C60. This cycloaddition and its lysine adduct provides the benefits of dense, covalent modification, ease of purification, commercial availability of reagents, and pH-dependent solubility of the product. Subsequently, SWCNTs functionalized with lysine amine handles were covalently conjugated to a radiometalated chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). The (111)In-labeled construct showed rapid renal clearance in a murine model and a favorable biodistribution, permitting utility in biomedical applications. Functionalized SWCNTs strongly wrapped small interfering RNA (siRNA). In the first disclosed deployment of thermophoresis with carbon nanotubes, the lysine-modified tubes showed a desirable, weak SWCNT-albumin binding constant. Thus, lysine-modified nanotubes are a favorable candidate for medicinal work.

  9. Biosafety of non-surface modified carbon nanocapsules as a potential alternative to carbon nanotubes for drug delivery purposes.

    Directory of Open Access Journals (Sweden)

    Alan C L Tang

    Full Text Available BACKGROUND: Carbon nanotubes (CNTs have found wide success in circuitry, photovoltaics, and other applications. In contrast, several hurdles exist in using CNTs towards applications in drug delivery. Raw, non-modified CNTs are widely known for their toxicity. As such, many have attempted to reduce CNT toxicity for intravenous drug delivery purposes by post-process surface modification. Alternatively, a novel sphere-like carbon nanocapsule (CNC developed by the arc-discharge method holds similar electric and thermal conductivities, as well as high strength. This study investigated the systemic toxicity and biocompatibility of different non-surface modified carbon nanomaterials in mice, including multi-walled carbon nanotubes (MWCNTs, single-walled carbon nanotubes (SWCNTs, carbon nanocapsules (CNCs, and C ₆₀ fullerene (C ₆₀. The retention of the nanomaterials and systemic effects after intravenous injections were studied. METHODOLOGY AND PRINCIPAL FINDINGS: MWCNTs, SWCNTs, CNCs, and C ₆₀ were injected intravenously into FVB mice and then sacrificed for tissue section examination. Inflammatory cytokine levels were evaluated with ELISA. Mice receiving injection of MWCNTs or SWCNTs at 50 µg/g b.w. died while C ₆₀ injected group survived at a 50% rate. Surprisingly, mortality rate of mice injected with CNCs was only at 10%. Tissue sections revealed that most carbon nanomaterials retained in the lung. Furthermore, serum and lung-tissue cytokine levels did not reveal any inflammatory response compared to those in mice receiving normal saline injection. CONCLUSION: Carbon nanocapsules are more biocompatible than other carbon nanomaterials and are more suitable for intravenous drug delivery. These results indicate potential biomedical use of non-surface modified carbon allotrope. Additionally, functionalization of the carbon nanocapsules could further enhance dispersion and biocompatibility for intravenous injection.

  10. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    Science.gov (United States)

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  11. ABTS-modified multiwalled carbon nanotubes as an effective mediating system for bioelectrocatalytic reduction of oxygen.

    Science.gov (United States)

    Karnicka, Katarzyna; Miecznikowski, Krzysztof; Kowalewska, Barbara; Skunik, Magdalena; Opallo, Marcin; Rogalski, Jerzy; Schuhmann, Wolfgang; Kulesza, Pawel J

    2008-10-01

    The ability of such a common redox mediator as 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) to undergo sorption on carbon surfaces is explored here to convert multiwalled carbon nanotubes (CNTs) into a stable colloidal solution of ABTS-modified carbon nanostructures, the diameters of which are approximately 10 nm (as determined by transmission electron microscopy). Subsequently, inks composed of fungal laccase (Cerrena unicolor) mixed with the dispersion of ABTS-modified CNTs and stabilized with Nafion, were deposited on glassy carbon and successfully employed to the reduction of oxygen in McIlvain buffer at pH 5.2. For comparison, the systems utilizing only ABTS-free CNTs and laccase as well as ABTS-modified CNTs did not show appreciable activity toward the oxygen reduction. The three-dimensionally distributed ABTS-modified CNTs are expected to improve the film's overall conductivity and to facilitate electrical connection between the electrode and the enzyme. The network film of ABTS-modified CNTs is rigid, and it is characterized by charge propagation capabilities comparable to the conventional redox polymers. The whole concept of utilization of CNTs modified with ultrathin films of redox mediators in the preparation of efficient bioelectrocatalytic films seems to be of general importance to electroanalytical chemistry and to the development of biosensors.

  12. Thermal property of regioregular poly(3-hexylthiophene)/nanotube composites using modified single-walled carbon nanotubes via ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Adhikari, A R [College of Nanoscale Science and Engineering, State University of New York, Albany, NY 12203 (United States); Huang, M [College of Nanoscale Science and Engineering, State University of New York, Albany, NY 12203 (United States); Bakhru, H [College of Nanoscale Science and Engineering, State University of New York, Albany, NY 12203 (United States); Chipara, M [Department of Physics and Geology, University of Texas Pan American, Edinburg, TX 78541-2999 (United States); Ryu, C Y [Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Ajayan, P M [Department of Material Science and Engineering, Rensselaer Polytechnic Institute, Troy and Rensselaer Nanotechnology Center, NY 12180 (United States)

    2006-12-28

    The effects of radiation-induced modifications on the thermal stability and phase transition behaviour of composites made of 1% pristine or ion irradiated single-walled carbon nanotubes (SWNTs) and poly(3-hexylthiophene) (P3HT) are reported. Thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy and electron spin resonance (ESR) were used to investigate the radiation-induced functionalization of carbon nanotubes and to assess the effect of ionizing radiation on the adhesion between macromolecular polymer and carbon nanotubes. Irradiation was used to introduce defects in a controlled way solely within pristine nanotubes before composite synthesis. The addition of irradiated SWNTs to a polymer matrix was found to enhance thermo-oxidative stability and phase transition behaviour. Further, ESR studies demonstrate the electronic interaction through charge transfer between filler and matrix. These results could have immense applications in nanotube composite processing. Based on the experimental data, a model for the interaction between polymeric chains and carbon nanotubes is proposed.

  13. Voltammetric determination of theophylline at a Nafion/multi-wall carbon nanotubes composite film-modified glassy carbon electrode

    Indian Academy of Sciences (India)

    Suling Yang; Ran Yang; Gang Li; Jianjun Li; Lingbo Qu

    2010-11-01

    A Nafion/multi-wall carbon nanotubes (MWNTs) composite film-modified electrode was fabricated and applied to the sensitive and convenient determination of theophylline (TP). Multi-wall carbon nanotubes (MWNTs) were easily dispersed homogeneously into 0.1% Nafion methanol solution by sonication. Appropriate amount of Nafion/MWNTs suspension was coated on a glassy carbon electrode. After evaporating methanol, a Nafion/MWNTs composite film-modified electrode was achieved. TP could effectively accumulate at Nafion/MWNTs composite film-modified electrode and cause a sensitive anodic peak at around 1180 mV (vs SCE) in 0.01 mol/L H2SO4 medium (pH 1.8). In contrast with the bare glassy carbon electrode, Nafion film-modified electrode, Nafion/MWNTs film-modified electrode could remarkably increase the anodic peak current and decreased the overpotential of TP oxidation. Under the optimized conditions, the anodic peak current was proportional to TP concentration in the range of 8.0 × 10-8-6.0 × 10-5 mol/L, with a detection limit of 2.0 × 10-8 mol/L. This newly developed method was used to determine TP in drug samples with good percentage of recoveries.

  14. Adsorptive stripping voltammetric determination of nitroimidazole derivative on multiwalled carbon nanotube modified electrodes: influence of size and functionalization of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jara-Ulloa, Paola; Canete-Rosales, Paulina; Nunez-Vergara, Luis J; Squella, Juan A., E-mail: asquella@ciq.uchile.c [University of Chile, Santiago (Chile). Chemical and Pharmaceutical Sciences Faculty. Bioelectrochemistry Lab.

    2011-07-01

    1-Methyl-4-nitro-2-bromine methylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified electrode thus permitting the implementation of an adsorptive stripping voltammetric (ASV) method. We have used 4-NimMeBr as a prototype electroactive nitro compound to study the effect of both the size of the nanotubes and its functionalization by oxidation. The oxidized MWCNT forms better dispersions than the non-oxidized, producing electrode surface with higher density of MWCNT as was determined by electrochemical mapping using scanning electrochemical microscopy (SECM). Under the optimized conditions, the peak current was proportional to the concentration of 4-NimMeBr in the range of 10{sup -6} mol L{sup -1} to 10{sup -4} mol L{sup -1} with detection and quantification limits of 4.41 x 10{sup -6} mol L{sup -1} and 6.21 x 10{sup -6} mol L{sup -1}, respectively. The sensibility of bare electrode was 0.01 {mu}A per mmol L{sup -1}, which was lower than the value of 5.34 and 6.97 mA per mmol L{sup -1} obtained using short and large oxidized MWCNT, respectively. (author)

  15. Modifying the electronic properties of single-walled carbon nanotubes using designed surfactant peptides

    Science.gov (United States)

    Samarajeewa, Dinushi R.; Dieckmann, Gregg R.; Nielsen, Steven O.; Musselman, Inga H.

    2012-07-01

    The electronic properties of carbon nanotubes can be altered significantly by modifying the nanotube surface. In this study, single-walled carbon nanotubes (SWCNTs) were functionalized noncovalently using designed surfactant peptides, and the resultant SWCNT electronic properties were investigated. These peptides have a common amino acid sequence of X(Valine)5(Lysine)2, where X indicates an aromatic amino acid containing either an electron-donating or electron-withdrawing functional group (i.e. p-amino-phenylalanine or p-cyano-phenylalanine). Circular dichroism spectra showed that the surfactant peptides primarily have random coil structures in an aqueous medium, both alone and in the presence of SWCNTs, simplifying analysis of the peptide/SWCNT interaction. The ability of the surfactant peptides to disperse individual SWCNTs in solution was verified using atomic force microscopy and ultraviolet-visible-near-infrared spectroscopy. The electronic properties of the surfactant peptide/SWCNT composites were examined using the observed nanotube Raman tangential band shifts and the observed additional features near the Fermi level in the scanning tunneling spectroscopy dI/dV spectra. The results revealed that SWCNTs functionalized with surfactant peptides containing electron-donor or electron-acceptor functional groups showed n-doped or p-doped altered electronic properties, respectively. This work unveils a facile and versatile approach to modify the intrinsic electronic properties of SWCNTs using a simple peptide structure, which is easily adaptable to obtain peptide/SWCNT composites for the design of tunable nanoscale electronic devices.The electronic properties of carbon nanotubes can be altered significantly by modifying the nanotube surface. In this study, single-walled carbon nanotubes (SWCNTs) were functionalized noncovalently using designed surfactant peptides, and the resultant SWCNT electronic properties were investigated. These peptides have a common amino

  16. Removal of diclofenac from aqueous solution with multi-walled carbon nanotubes modified by nitric acid☆

    Institute of Scientific and Technical Information of China (English)

    Xiang Hu; Zhao Cheng

    2015-01-01

    Modified multi-walled carbon nanotubes (MWCNTs) were used as adsorbents for removal of diclofenac. The re-action conditions were examined. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models were applied to determine appropriate equilibrium expression. The results show that the experimental data fit the Freundlich equation well. Thermodynamic parameters show that the adsorption process is spontaneous and exothermic. The kinetic study indicates that the adsorption of diclofenac can be well described with the pseudo-second-order kinetic model and the process is controlled by multiple steps.

  17. Quinoline Group Modified Carbon Nanotubes for the Detection of Zinc Ions

    Directory of Open Access Journals (Sweden)

    Dong Zhengping

    2009-01-01

    Full Text Available Abstract Carbon nanotubes (CNTs were covalently modified by fluorescence ligand (glycine-N-8-quinolylamide and formed a hybrid material which could be used as a selective probe for metal ions detection. The anchoring to the surface of the CNTs was carried out by the reaction between the precursor and the carboxyl groups available on the surface of the support. Fourier transform infrared spectroscopy (FTIR and Thermogravimetric analysis (TGA unambiguously proved the existence of covalent bonds between CNTs and functional ligands. Fluorescence characterization shows that the obtained organic–inorganic hybrid composite is highly selective and sensitive (0.2 μM to Zn(II detection.

  18. Reversible electrochemistry of DNA on multi-walled carbon nanotube modified electrode

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues,respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.(C) 2007 Hong Xia Luo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  19. Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue

    Institute of Scientific and Technical Information of China (English)

    Shu Ping Zhang; Lian Gang Shan; Zhen Ran Tian; Yi Zheng; Li Yi Shi; Deng Song Zhang

    2008-01-01

    The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes(MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase(ACHE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected byusing i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrodewith 0.01U activity value and the detection limit of carbaryl is 10-12 g L-1 so the enzyme biosensor showed good properties forpesticides residue detection.2008 Shu Ping Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  20. Optical properties of carbon nanostructures produced by laser irradiation on chemically modified multi-walled carbon nanotubes

    Science.gov (United States)

    Santiago, Enrique Vigueras; López, Susana Hernández; Camacho López, Marco A.; Contreras, Delfino Reyes; Farías-Mancilla, Rurik; Flores-Gallardo, Sergio G.; Hernández-Escobar, Claudia A.; Zaragoza-Contreras, E. Armando

    2016-10-01

    This research focused on the nanosecond (Nd: YAG-1064 nm) laser pulse effect on the optical and morphological properties of chemically modified multi-walled carbon nanotubes (MWCNT). Two suspensions of MWCNT in tetrahydrofuran (THF) were prepared, one was submitted to laser pulses for 10 min while the other (blank) was only mechanically homogenized during the same time. Following the laser irradiation, the suspension acquired a yellow-amber color, in contrast to the black translucent appearance of the blank. UV-vis spectroscopy confirmed this observation, showing the blank a higher absorption. Additionally, photoluminescence measurements exhibited a broad blue-green emission band both in the blank and irradiated suspension when excited at 369 nm, showing the blank a lower intensity. However, a modification in the excitation wavelength produced a violet to green tuning in the irradiated suspension, which did not occur in the blank. Lastly, the electron microscopy analysis of the treated nanotubes showed the abundant formation of amorphous carbon, nanocages, and nanotube unzipping, exhibiting the intense surface modification produced by the laser pulse. Nanotube surface modification and the coexistence with the new carbon nanostructures were considered as the conductive conditions for optical properties modification.

  1. Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

    Science.gov (United States)

    Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

    2017-02-01

    The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

  2. Development of electrochemical oxidase biosensors based on carbon nanotube-modified carbon film electrodes for glucose and ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Gouveia-Caridade, Carla; Pauliukaite, Rasa; Brett, Christopher M.A. [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra (Portugal)

    2008-10-01

    Functionalised multi-walled carbon nanotubes (MWCNTs) were cast on glassy carbon (GC) and carbon film electrodes (CFE), and were characterised electrochemically and applied in a glucose-oxidase-based biosensor. MWCNT-modified carbon film electrodes were then used to develop an alcohol oxidase (AlcOx) biosensor, in which AlcOx-BSA was cross-linked with glutaraldehyde and attached by drop-coating. The experimental conditions, applied potential and pH, for ethanol monitoring were optimised, and ethanol was determined amperometrically at -0.3 V vs. SCE at pH 7.5. Electrocatalytic effects of MWCNT were observed with respect to unmodified carbon film electrodes. The sensitivity obtained was 20 times higher at carbon film/MWCNT-based biosensors than without MWCNT. (author)

  3. Multi-walled Carbon Nanotubes/Graphite Nanosheets Modified Glassy Carbon Electrode for the Simultaneous Determination of Acetaminophen and Dopamine.

    Science.gov (United States)

    Zhang, Susu; He, Ping; Zhang, Guangli; Lei, Wen; He, Huichao

    2015-01-01

    Graphite nanosheets prepared by thermal expansion and successive sonication were utilized for the construction of a multi-walled carbon nanotubes/graphite nanosheets based amperometric sensing platform to simultaneously determine acetaminophen and dopamine in the presence of ascorbic acid in physiological conditions. The synergistic effect of multi-walled carbon nanotubes and graphite nanosheets catalyzed the electrooxidation of acetaminophen and dopamine, leading to a remarkable potential difference up to 200 mV. The as-prepared modified electrode exhibited linear responses to acetaminophen and dopamine in the concentration ranges of 2.0 × 10(-6) - 2.4 × 10(-4) M (R = 0.999) and 2.0 × 10(-6) - 2.0 × 10(-4) M (R = 0.998), respectively. The detection limits were down to 2.3 × 10(-7) M for acetaminophen and 3.5 × 10(-7) M for dopamine (S/N = 3). Based on the simple preparation and prominent electrochemical properties, the obtained multi-walled carbon nanotubes/graphite nanosheets modified electrode would be a good candidate for the determination of acetaminophen and dopamine without the interference of ascorbic acid.

  4. Synthesis, pharmacokinetics, and biological use of lysine-modified single-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Mulvey JJ

    2014-09-01

    Full Text Available J Justin Mulvey,1,2 Evan N Feinberg,1,3 Simone Alidori,1 Michael R McDevitt,4,5 Daniel A Heller,1,6 David A Scheinberg1,5,6 1Molecular Pharmacology and Chemistry Program, Sloan Kettering Institute, New York, NY, USA; 2Tri-Institutional MD-PhD Program, New York, NY, USA; 3Department of Applied Physics, Yale University, New Haven, CT USA; 4Department of Radiology and 5Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA; 6Weill Cornell Medical College, New York, NY, USA Abstract: We aimed to create a more robust and more accessible standard for amine-modifying single-walled carbon nanotubes (SWCNTs. A 1,3-cycloaddition was developed using an azomethine ylide, generated by reacting paraformaldehyde and a side-chain-Boc (tert-Butyloxycarbonyl-protected, lysine-derived alpha-amino acid, H-Lys(Boc-OH, with purified SWCNT or C60. This cycloaddition and its lysine adduct provides the benefits of dense, covalent modification, ease of purification, commercial availability of reagents, and pH-dependent solubility of the product. Subsequently, SWCNTs functionalized with lysine amine handles were covalently conjugated to a radiometalated chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA. The 111In-labeled construct showed rapid renal clearance in a murine model and a favorable biodistribution, permitting utility in biomedical applications. Functionalized SWCNTs strongly wrapped small interfering RNA (siRNA. In the first disclosed deployment of thermophoresis with carbon nanotubes, the lysine-modified tubes showed a desirable, weak SWCNT-albumin binding constant. Thus, lysine-modified nanotubes are a favorable candidate for medicinal work. Keywords: fullerene, cycloaddition, azomethine, DOTA, thermophoresis, 111In

  5. Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

    Science.gov (United States)

    Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

    2015-07-01

    In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

  6. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    Science.gov (United States)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  7. Carbon Nanotube Purification and Functionalization

    Science.gov (United States)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  8. Synthesis and Characterizations of Poly(3-hexylthiophene and Modified Carbon Nanotube Composites

    Directory of Open Access Journals (Sweden)

    Mohammad Rezaul Karim

    2012-01-01

    Full Text Available Poly(3-hexylthiophene and modified (functionalized and silanized multiwall carbon nanotube (MWNT nanocomposites have been prepared through in situ polymerization process in chloroform medium with FeCl3 oxidant at room temperature. The composites are characterized through Fourier transfer infrared spectroscopy (FT-IR, Raman, and X-ray diffraction (XRD measurements to probe the nature of interaction between the moieties. Optical properties of the composites are measured from ultraviolet-visible (UV-Vis and photoluminescence (PL spectroscopy. Conductivity of the composites is followed by four probe techniques to understand the conduction mechanism. The change (if any in C=C symmetric and antisymmetric stretching frequencies in FT-IR, the shift in G band frequencies in Raman, any alterations in λmax of UV-Vis, and PL spectroscopic measurements are monitored with modified MWNT loading in the polymer matrix.

  9. Monitoring of dopamine release in single cell using ultrasensitive ITO microsensors modified with carbon nanotubes.

    Science.gov (United States)

    Shi, Bao-Xian; Wang, Yu; Zhang, Kai; Lam, Tin-Lun; Chan, Helen Lai-Wa

    2011-02-15

    The study of single cell dynamics has been greatly adapted in biological and medical research and applications. In this work a novel microfluidic electrochemical sensor with carbon nanotubes (CNTs) modified indium tin oxide (ITO) microelectrode was developed for single cells release monitoring. The sensitivity of the electrochemical sensor after CNTs surface modification was improved by 2.5-3 orders of magnitude. The developed CNTs modified ITO sensor was successfully employed to monitor the dopamine release from single living rat pheochromocytoma (PC 12) cells. Its ultrahigh sensitivity, transparency and need for fewer agents enable this smart electrochemical sensor to become a powerful tool in recording dynamic release from various living tissues and organs optically and electrically.

  10. Electrochemical properties of seamless three-dimensional carbon nanotubes-grown graphene modified with horseradish peroxidase.

    Science.gov (United States)

    Komori, Kikuo; Terse-Thakoor, Trupti; Mulchandani, Ashok

    2016-10-01

    Horseradish peroxidase (HRP) was immobilized through sodium dodecyl sulfate (SDS) on the surface of a seamless three-dimensional hybrid of carbon nanotubes grown at the graphene surface (HRP-SDS/CNTs/G) and its electrochemical properties were investigated. Compared with graphene alone electrode modified with HRP via SDS (HRP-SDS/G electrode), the surface coverage of electroactive HRP at the CNTs/G electrode surface was approximately 2-fold greater because of CNTs grown at the graphene surface. Based on the increase in the surface coverage of electroactive HRP, the sensitivity to H2O2 at the HRP-SDS/CNTs/G electrode was higher than that at the HRP-SDS/G electrode. The kinetics of the direct electron transfer from the CNTs/G electrode to compound I and II of modified HRP was also analyzed.

  11. Direct Electrochemistry of Glucose Oxidase at a Gold Electrode Modified with Single-Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yuan Zhuobin

    2003-12-01

    Full Text Available The direct electrochemistry of glucose oxidase (GOD was accomplished at a gold electrode modified with single-wall carbon nanotubes (SWNTs. A pair of welldefined redox peaks was obtained for GOD with the reduction peak potential at –0.465 V and a peak potential separation of 23 mV at pH 7.0. Both FT-IR spectra and the dependence of the reduction peak current on the scan rate revealed that GOD adsorbed onto the SWNT surfaces. The redox wave corresponds to the redox center of the flavin adenine dinucleotide(FAD of the GOD adsorbate. The electron transfer rate of GOD redox reaction was greatly enhanced at the SWNT-modified electrode. The peak potential was shown to be pH dependent. Verified by spectral methods, the specific enzyme activity of GOD adsorbates at the SWNTs appears to be retained.

  12. Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

    Directory of Open Access Journals (Sweden)

    FATEMEH KARIMI

    2009-12-01

    Full Text Available A chemically modified carbon paste electrode (MCPE containing ferrocene (FC and carbon nanotubes (CNT was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD in phosphate buffer solution (PBS. A linear concentration range of 5 to 600 μM CD, with a detection limit of 3.6±0.17 μM CD, was obtained. The diffusion coefficient of CD and the transfer coefficient ( were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples.

  13. Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode.

    Science.gov (United States)

    Teixeira, Meryene C; Tavares, Elisângela de F L; Saczk, Adelir A; Okumura, Leonardo L; Cardoso, Maria das Graças; Magriotis, Zuy M; de Oliveira, Marcelo F

    2014-07-01

    We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).

  14. Voltammetric determination of carbidopa and folic acid using a modified carbon nanotubes paste electrode

    Directory of Open Access Journals (Sweden)

    Keshtkar Nasrin

    2015-01-01

    Full Text Available A novel electrochemical sensor for the selective and sensitive detection of carbidopa in presence of large excess of folic acid at physiological pH was developed by the bulk modification of carbon paste electrode (CPE with carbon nanotubes (CNTs and vinylferrocene. Large peak separation, good sensitivity and stability allow this modified electrode to analyze carbidopa individually and simultaneously along with folic acid. Applying square wave voltammetry (SWV, a linear dynamic range of 1.0×10-6- 7.0×10-4 M with detection limit of 2.0×10-7 M was obtained for carbidopa. Finally, the proposed method was applied to the determination of carbidopa and folic acid in urine sample.

  15. Amine-modified single-walled carbon nanotubes protect neurons from injury in a rat stroke model

    Science.gov (United States)

    Lee, Hyun Jung; Park, Jiae; Yoon, Ok Ja; Kim, Hyun Woo; Lee, Do Yeon; Kim, Do Hee; Lee, Won Bok; Lee, Nae-Eung; Bonventre, Joseph V.; Kim, Sung Su

    2011-02-01

    Stroke results in the disruption of tissue architecture and is the third leading cause of death in the United States. Transplanting scaffolds containing stem cells into the injured areas of the brain has been proposed as a treatment strategy, and carbon nanotubes show promise in this regard, with positive outcomes when used as scaffolds in neural cells and brain tissues. Here, we show that pretreating rats with amine-modified single-walled carbon nanotubes can protect neurons and enhance the recovery of behavioural functions in rats with induced stroke. Treated rats showed less tissue damage than controls and took longer to fall from a rotating rod, suggesting better motor functions after injury. Low levels of apoptotic, angiogenic and inflammation markers indicated that amine-modified single-walled carbon nanotubes protected the brains of treated rats from ischaemic injury.

  16. Characteristics of a novel calix[8]arene modified with carbon nanotubes thin films for metal cations detection

    Science.gov (United States)

    Supian, Faridah Lisa; Bakar, Suriani Abu; Azahari, Noor Azyyati; Richardson, Tim H.

    2013-05-01

    This study focuses on the properties of a novel calix[8]arene that have been modified with carbon nanotubes (CNT) as ion sensor application. Calix[8]arene modified with carbon nanotubes were done by mixing CNT (Calix8A-CNT) with a novel calix[8]arene in a long ultrasonication process. This study is interesting due to the process on the attaching of the functionalization of the calixarene on the carbon nanotubes outer wall. Morphological and spectroscopic studies of Calix8A-CNT were done using Π-A isotherm, Surface Potential Probe (S-Pot), Field mission scanning electron microscopy (FE-SEM) and Raman spectroscopy in order to understand the behavior in the molecular level. This water-soluble supramolecular hybrid materials have potential as metal cations detection and nanoelectronics applications, yet the CNT provide the thermal stability to the polymers.

  17. Synthesis and characterization of carbon modified TiO{sub 2} nanotube and photocatalytic activity on methylene blue under sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yinchang [Faculty of Material Science and Chemistry, China University of Geoscience, Wuhan 430074 (China); Wang, Yongqian, E-mail: cugwyq@126.com [Faculty of Material Science and Chemistry, China University of Geoscience, Wuhan 430074 (China); Zhejiang Research Institute, China University of Geosciences, Hanzhou 311305 (China); Kong, Junhan; Jia, Hanxiang; Wang, Zhengshu [Faculty of Material Science and Chemistry, China University of Geoscience, Wuhan 430074 (China)

    2015-07-30

    Graphical abstract: Tentative photo-degradation mechanism diagram of the MB on the surface of carbon modified TNT. When the TiO{sub 2} was under ultraviolet light irradiation, the electrons were excited and transferred from the valence band (VB) to the conduction band (CB), leaving the holes on VB. The electrons were trapped by O{sub 2} and formed superoxide anion (O{sub 2}{sup −}). H{sub 2}O around the TiO{sub 2} was oxidized by the holes leaved on VB to hydroxyl radicals (OH·). When the TiO{sub 2} was modified by carbon, the same is that the electrons of C{sup 4+} would be excited from ground state to 2P orbital under visible light irradiation. The electrons and holes can also lead to the generation of the O{sub 2}{sup −} and OH·. The oxidability of O{sub 2}{sup −} and OH· created around the carbon modified TNT is strong, and could oxidize the MB to CO{sub 2} and H{sub 2}O. - Highlights: • The TNT was successfully modified by carbon, its amount is about 4.95%. • The carbon modified TNT has a great enhancement of visible light absorption. • The photocatalytic ability of carbon modified TNT is higher than pristine TNT. • A tentative photo-degradation mechanism of carbon modified TNT is proposed. - Abstract: Carbon modified TiO{sub 2} nanotube was successfully synthesized via anodic oxidation method and its photocatalytic activity was evaluated by photodegrading methylene blue. The full width at half maximum of carbon modified TiO{sub 2} nanotube is smaller than that of pristine TiO{sub 2} nanotube, indicating the fact that carbon modifying leads to the increase of TiO{sub 2} crystallinity. TiO{sub 2} nanotube modified by carbon has a great enhancement on visible light absorption while contrasting with the pristine TiO{sub 2} nanotube. A tentative mechanism for the enhancement of sunlight absorption is proposed.

  18. New Electrochemically-Modified Carbon Paste Inclusion β-Cyclodextrin and Carbon Nanotubes Sensors for Quantification of Dorzolamide Hydrochloride

    Directory of Open Access Journals (Sweden)

    Nawal Ahmad Alarfaj

    2016-12-01

    Full Text Available The present article introduces a new approach to fabricate carbon paste sensors, including carbon paste, modified carbon paste inclusion β-cyclodextrin, and carbon nanotubes for the quantification of dorzolamide hydrochloride (DRZ. This study is mainly based on the construction of three different carbon paste sensors by the incorporation of DRZ with phosphotungstic acid (PTA to form dorzolamide-phosphotungstate (DRZ-PT as an electroactive material in the presence of the solvent mediator ortho-nitrophenyloctyl ether (o-NPOE. The fabricated conventional carbon paste sensor (sensor I, as well as the other modified carbon paste sensors using β-cyclodextrin (sensor II and carbon nanotubes (sensor III, have been investigated. The sensors displayed Nernstian responses of 55.4 ± 0.6, 56.4 ± 0.4 and 58.1 ± 0.2 mV·decade−1 over concentration ranges of 1.0 × 10−5–1.0 × 10−2, 1.0 × 10−6–1.0 × 10−2, and 5.0 × 10−8–1.0 × 10−2 mol·L−1 with lower detection limits of 5.0 × 10−6, 5.0 × 10−7, and 2.5 × 10−9 mol·L−1 for sensors I, II, and III, respectively. The critical performance of the developed sensors was checked with respect to the effect of various parameters, including pH, selectivity, response time, linear concentration relationship, lifespan, etc. Method validation was applied according to the international conference on harmonisation of technical requirements for registration of pharmaceuticals for human use ICH guidelines. The developed sensors were employed for the determination of DRZ in its bulk and dosage forms, as well as bio-samples. The observed data were statistically analyzed and compared with those obtained from other published methods.

  19. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2013-01-01

    Full Text Available The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR. The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM and transmission electron microscope (TEM. It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques.

  20. Application of multi-walled carbon nanotubes modified carbon ionic liquid electrode for electrocatalytic oxidation of dopamine.

    Science.gov (United States)

    Li, Yonghong; Liu, Xinsheng; Liu, Xiaoying; Mai, Nannan; Li, Yuandong; Wei, Wanzhi; Cai, Qingyun

    2011-11-01

    A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0×10(-8) to 2.0×10(-4) mol L(-1) and the detection limit was 1.0×10(-8) mol L(-1).

  1. Carbon nanotube composite materials

    Energy Technology Data Exchange (ETDEWEB)

    O' Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  2. Electroanalysis of NADH Using Conducting and Redox Active Polymer/Carbon Nanotubes Modified Electrodes-A Review

    Directory of Open Access Journals (Sweden)

    Shen-Ming Chen

    2008-01-01

    Full Text Available Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the potential uses of electrogenerated polymer modified electrodes and polymer/carbon nanotubes composite modified electrodes for electroanalysis of reduced form of nicotinamide adenine dinuceltoide (NADH. In addition, carbon electrodes modified with organic and inorganic materials as modifier have been discussed in detail for the quantification of NADH based on mediator or mediator-less methods.

  3. Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

    Directory of Open Access Journals (Sweden)

    Sushil Kumar

    2012-05-01

    Full Text Available Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA by square-wave voltammetry (SWV. The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd. Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047–5.0 mmol/L and displayed good linearity (R2 = 0.994. The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96–104% with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99–104%. The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05.

  4. Simultaneous determination of nitrophenol isomers at the single-wall carbon nanotube compound conducting polymer film modified electrode

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; WANG Zhenhui; ZHOU Shuping

    2005-01-01

    Based on the molecular recognition ability of conductive polymer and the peculiar properties of carbon nanotubes, a novel single wall nanotubes (SWNTs) compound poly(4- aminopyridine) modified electrode (SWNTs/POAPE) is prepared at glass carbon electrode (GCE). The electrochemistry response of nitrophenol isomers is studied at the SWNTs/POAPE. The result indicates that o-, m- and p-nitrophenol are separated entirely at the SWNTs/POAPE interface. The electrode present here can be easily used to determine nitrophenol isomers simultaneously with higher sensitivity.

  5. Mechanical, Rheological and Thermal Properties of Polystyrene/1-Octadecanol Modified Carbon Nanotubes Nanocomposites

    KAUST Repository

    Amr, Issam Thaher

    2014-09-04

    The results of the studies on the functionalization of multi-walled carbon nanotubes (MWCNT) with 1-octadecanol and its usage as reinforcing filler in the bulk polymerization of styrene are reported in this article. Both unmodified and modified CNTs were utilized in different loadings, however, without any initiator. The resulting composites were characterized by using mechanical testing, differential scanning calorimetry, thermogravimetric analysis and melt rheology. The tensile tests show the addition of 0.5wt% of CNT-C18 results in 19.5% increment of Young\\'s modulus. The DSC study shows a decrease in T-g values of prepared PS/CNT nanocomposite. The rheological study was conducted at 190 degrees C and shows that addition of pure CNT increased the viscoelastic behavior of the PS matrices, while the CNT-C18 act as plasticizer. Thermogravimetric analysis shows that the incorporation of CNT into PS enhanced the thermal properties significantly.

  6. Carbon nanotubes modified with SnO{sub 2} rods for levofloxacin detection

    Energy Technology Data Exchange (ETDEWEB)

    Cesarino, Vivian [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Escola de Engenharia; Cesarino, Ivana; Moraes, Fernando C.; Machado, Sergio A.S., E-mail: ivana@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Mascaro, Lucia H. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica

    2014-03-15

    A new sensor based on multi-walled carbon nanotubes modified with SnO{sub 2} rods for the electrochemical determination of levofloxacin has been investigated. The morphology, the structure, and the electrochemical performance of the composite electrode were characterised by scanning electron microscopy, energy dispersive X-ray spectroscopy, and cyclic voltammetry, respectively. Differential pulse voltammetry in phosphate buffer solution at pH 6.0, allowed the application of a method to determine levofloxacin levels in a range of 1.0-9.9 μmol L{sup -1}, with a limit of detection calculated at 0.2 μmol L{sup -1} (72.0 mg L{sup -1}). (author)

  7. Microstructure and activation characteristics of Mg-Ni alloy modified by multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Aminorroaya, Sima; Liu, Hua Kun [Institute for Superconducting and Electronic Materials, University of Wollongong, Fairy Meadow, NSW 2522 (Australia); CSIRO National Hydrogen Materials Alliance, CSIRO Energy Centre, 10 Murray Dwyer Circuit, Steel River Estate, Mayfield West, NSW 2304 (Australia); Cho, Younghee; Dahle, Arne [CSIRO National Hydrogen Materials Alliance, CSIRO Energy Centre, 10 Murray Dwyer Circuit, Steel River Estate, Mayfield West, NSW 2304 (Australia); Materials Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2010-05-15

    An Mg-6 wt% Ni alloy was fabricated by a casting technique and the drilled chips ball-milled by high energy ball milling to be examined for their hydrogenation modified with multi-walled carbon nanotubes (MWCNTs). The activation characteristics of ball-milled alloy are compared with those of the materials obtained by ball milling with 5 wt% MWCNTs for 0.5, 1, 2, 5 and 10 h. MWCNTs enhanced the absorption kinetics considerably in all cases. The hydrogen content of the modified powder with MWCNTs reached maximum hydrogen capacity within 2 min of exposure to hydrogen at 370 C and 2 MPa pressure. X-ray diffraction analysis provided evidence that no carbon-containing phase was formed during milling. However, milling with MWCNTs reduced the crystallite size, even if the milling was carried out for only an hour. The rate-controlling steps of the hydriding reactions at different milling times were determined by fitting the respective kinetic equations. Evidence is provided that nucleation and growth of hydrides are accelerated drastically by a homogenous distribution of MWCNTs on the surface of the ball-milled powders. We show that MWCNTs are very effective at promoting the hydriding/dehydriding kinetics, as well as in increasing the hydrogen capacity of the magnesium alloy. (author)

  8. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Uicab, O. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Avilés, F., E-mail: faviles@cicy.mx [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Gonzalez-Chi, P.I; Canché-Escamilla, G.; Duarte-Aranda, S. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Yazdani-Pedram, M. [Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, S. Livingstone 1007, Independencia, Santiago (Chile); Toro, P. [Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Beauchef 850, Santiago (Chile); Gamboa, F. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Mérida, Depto. de Física Aplicada, Km. 6 Antigua Carretera a Progreso, 97310 Mérida, Yucatán (Mexico); Mazo, M.A.; Nistal, A.; Rubio, J. [Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid (Spain)

    2016-11-01

    Highlights: • The surface of aramid fibers was functionalized by two acid treatments. • The treatment based on HNO{sub 3}/H{sub 2}SO{sub 4} reduced the mechanical properties of the fibers. • CNTs were deposited on the aramid fibers, reaching electrical conductivity. • Homogeneous CNT distribution was achieved by using pristine fibers or chlorosulfonic acid. - Abstract: Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating (“sizing”), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  9. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Science.gov (United States)

    Rodríguez-Uicab, O.; Avilés, F.; Gonzalez-Chi, P. I.; Canché-Escamilla, G.; Duarte-Aranda, S.; Yazdani-Pedram, M.; Toro, P.; Gamboa, F.; Mazo, M. A.; Nistal, A.; Rubio, J.

    2016-11-01

    Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating ("sizing"), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  10. Direct Electrochemical Oxidation of NADPH at a Low Potential on the Carbon Nanotube Modified Glassy Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    CHEN, Jing(陈静); CAI, Chen-Xin(蔡称心)

    2004-01-01

    NADPH can be directly oxidized on a carbon nanotube modified glassy carbon (CNT/GC) electrode in phosphate buffer solution (pH=6.0) with a diminution of the overpotential of more than 700 mV. The anodic peak currents increase linearly with the increase of concentration of NADPH in the range of 5×10-7 to 1×10-3 mol/L with a detection limit of about 1×10-7 mol/L. The CNT/GC electrode exhibits high sensitivity, low potential and stability in detecting NADPH and thus might be used in biosensors to study the electrocatalytic reaction of important dehydrogenase-based biological systems.

  11. Pristine multi-walled carbon nanotubes/SDS modified carbon paste electrode as an amperometric sensor for epinephrine.

    Science.gov (United States)

    Thomas, Tony; Mascarenhas, Ronald J; D' Souza, Ozma J; Detriche, Simon; Mekhalif, Zineb; Martis, Praveen

    2014-07-01

    An amperometric sensor for the determination of epinephrine (EP) was fabricated by modifying the carbon paste electrode (CPE) with pristine multi-walled carbon nanotubes (pMWCNTs) using bulk modification followed by drop casting of sodium dodecyl sulfate (SDS) onto the surface for its optimal potential application. The modified electrode showed an excellent electrocatalytic activity towards EP by decreasing the overpotential and greatly enhancing the current sensitivity. FE-SEM images confirmed the dispersion of pMWCNTs in the CPE matrix. EDX analysis ensured the surface coverage of SDS. A comparative study of pMWCNTs with those of oxidized MWCNTs (MWCNTsOX) modified electrodes reveals that the former is the best base material for the construction of the sensor with advantages of lower oxidation overpotential and the least background current. The performance of the modified electrode was impressive in terms of the least charge transfer resistance (Rct), highest values for diffusion coefficient (DEP) and standard heterogeneous electron transfer rate constant (k°). Analytical characterization of the modified electrode exhibited two linear dynamic ranges from 1.0×10(-7) to 1.0×10(-6)M and 1.0×10(-6) to 1.0×10(-4)M with a detection limit of (4.5±0.18)×10(-8)M. A 100-fold excess of serotonin, acetaminophen, folic acid, uric acid, tryptophan, tyrosine and cysteine, 10-fold excess of ascorbic acid and twofold excess of dopamine do not interfere in the quantification of EP at this electrode. The analytical applications of the modified electrode were demonstrated by determining EP in spiked blood serum and adrenaline tartrate injection. The modified electrode involves a simple fabrication procedure, minimum usage of the modifier, quick response, excellent stability, reproducibility and anti-fouling effects.

  12. Sol-gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces.

    Science.gov (United States)

    Maho, Anthony; Detriche, Simon; Delhalle, Joseph; Mekhalif, Zineb

    2013-07-01

    Carbon nanotubes used as fillers in composite materials are more and more appreciated for the outstanding range of accessible properties and functionalities they generate in numerous domains of nanotechnologies. In the framework of biological and medical sciences, and particularly for orthopedic applications and devices (prostheses, implants, surgical instruments, …), titanium substrates covered by tantalum oxide/carbon nanotube composite coatings have proved to constitute interesting and successful platforms for the conception of solid and biocompatible biomaterials inducing the osseous regeneration processes (hydroxyapatite growth, osteoblasts attachment). This paper describes an original strategy for the conception of resistant and homogeneous tantalum oxide/carbon nanotubes layers on titanium through the introduction of carbon nanotubes functionalized by phosphonic acid moieties (-P(=O)(OH)2). Strong covalent C-P bonds are specifically inserted on their external sidewalls with a ratio of two phosphonic groups per anchoring point. Experimental results highlight the stronger "tantalum capture agent" effect of phosphonic-modified nanotubes during the sol-gel formation process of the deposits compared to nanotubes bearing oxidized functions (-OH, -C=O, -C(=O)OH). Particular attention is also paid to the relative impact of the rate of functionalization and the dispersion degree of the carbon nanotubes in the coatings, as well as their wrapping level by the tantalum oxide matrix material. The resulting effect on the in vitro growth of hydroxyapatite is also evaluated to confirm the primary osseous bioactivity of those materials. Chemical, structural and morphological features of the different composite deposits described herein are assessed by X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission (TEM) electronic microscopies, energy dispersive X-rays analysis (EDX) and peeling tests.

  13. A multiwall carbon nanotubes film-modified carbon fiber ultramicroelectrode for the determination of nitric oxide radical in liver mitochondria.

    Science.gov (United States)

    Wang, Yazhen; Li, Qing; Hu, Shengshui

    2005-02-01

    A novel chemically modified electrode based on the multiwall carbon nanotubes (MWNTs) film-coated carbon fiber ultramicroelectrode (CFUE) has been described for the determination of nitric oxide radical (.NO). The electrochemical behaviors of MWNTs-modified CFUE have been characterized in 0.2 mmol L(-1) K(4)Fe(CN)(6) and 0.1 mol L(-1) KCl solution. The Nafion film was used to avoid some electroactive interferences. The amount of Nafion was optimized, and some possible interferents [such as nitrite (NO(2)(-)), nitrate (NO(3)(-)), ascorbate, dopamine (DA), l-arginine (l-Arg), etc.] were tested and evaluated. The oxidation peak current of .NO increases significantly at the MWNT/Nafion-modified CFUE, in contrast to that at the bare and the Nafion-modified CFUE, and the oxidation peak potential is at 0.78 V (vs. SCE), which can be used for the detection of .NO. The oxidation peak current is linearly with the concentration of .NO from 2x10(-7) to 8.6x10(-5) mol L(-1), and the detection limit is 2x10(-8) mol L(-1). The liver mitochondria in Carassius auratus were isolated and .NO release from mitochondria was monitored by using this ultramicroelectrode system.

  14. Electrochemical sensors and biosensors based on redox polymer/carbon nanotube modified electrodes: a review.

    Science.gov (United States)

    Barsan, Madalina M; Ghica, M Emilia; Brett, Christopher M A

    2015-06-30

    The aim of this review is to present the contributions to the development of electrochemical sensors and biosensors based on polyphenazine or polytriphenylmethane redox polymers together with carbon nanotubes (CNT) during recent years. Phenazine polymers have been widely used in analytical applications due to their inherent charge transport properties and electrocatalytic effects. At the same time, since the first report on a CNT-based sensor, their application in the electroanalytical chemistry field has demonstrated that the unique structure and properties of CNT are ideal for the design of electrochemical (bio)sensors. We describe here that the specific combination of phenazine/triphenylmethane polymers with CNT leads to an improved performance of the resulting sensing devices, because of their complementary electrical, electrochemical and mechanical properties, and also due to synergistic effects. The preparation of polymer/CNT modified electrodes will be presented together with their electrochemical and surface characterization, with emphasis on the contribution of each component on the overall properties of the modified electrodes. Their importance in analytical chemistry is demonstrated by the numerous applications based on polymer/CNT-driven electrocatalytic effects, and their analytical performance as (bio) sensors is discussed.

  15. Polyethylene-glycol-modified single-walled carbon nanotubes for intra-articular delivery to chondrocytes.

    Science.gov (United States)

    Sacchetti, Cristiano; Liu-Bryan, Ru; Magrini, Andrea; Rosato, Nicola; Bottini, Nunzio; Bottini, Massimo

    2014-12-23

    Osteoarthritis (OA) is a common and debilitating degenerative disease of articular joints for which no disease-modifying medical therapy is currently available. Inefficient delivery of pharmacologic agents into cartilage-resident chondrocytes after systemic administration has been a limitation to the development of anti-OA medications. Direct intra-articular injection enables delivery of high concentrations of agents in close proximity to chondrocytes; however, the efficacy of this approach is limited by the fast clearance of small molecules and biomacromolecules after injection into the synovial cavity. Coupling of pharmacologic agents with drug delivery systems able to enhance their residence time and cartilage penetration can enhance the effectiveness of intra-articularly injected anti-OA medications. Herein we describe an efficient intra-articular delivery nanosystem based on single-walled carbon nanotubes (SWCNTs) modified with polyethylene glycol (PEG) chains (PEG-SWCNTs). We show that PEG-SWCNTs are capable to persist in the joint cavity for a prolonged time, enter the cartilage matrix, and deliver gene inhibitors into chondrocytes of both healthy and OA mice. PEG-SWCNT nanoparticles did not elicit systemic or local side effects. Our data suggest that PEG-SWCNTs represent a biocompatible and effective nanocarrier for intra-articular delivery of agents to chondrocytes.

  16. Chronocoulometry of wine on multi-walled carbon nanotube modified electrode: Antioxidant capacity assay.

    Science.gov (United States)

    Ziyatdinova, Guzel; Kozlova, Ekaterina; Budnikov, Herman

    2016-04-01

    Phenolic antioxidants of wine were electrochemically oxidized on multi-walled carbon nanotubes modified glassy carbon electrode (MWNT/GCE) in phosphate buffer solution. Three oxidation peaks were observed at 0.39, 0.61 and 0.83V for red dry wine and 0.39, 0.80 and 1.18 V for white dry wine, respectively, using differential pulse voltammetry at pH 4.0. The oxidation potentials for individual phenolic antioxidants confirmed the integral nature of the analytical signals for the wines examined. A one-step chronocoulometric method at 0.83 and 1.18 V for red and white wines, respectively, has been developed for the evaluation of wine antioxidant capacity (AOC). The AOC is expressed in gallic acid equivalents per 1L of wine. The AOC of white wine was significantly less than red wine (386 ± 112 vs. 1224 ± 184, pwine and total antioxidant capacity, based on coulometric titration with electrogenerated bromine (r=0.8957 at n=5 and r=0.8986 at n=4 for red and white wines, respectively).

  17. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  18. Cobalt oxide nanoparticle-modified carbon nanotubes as an electrocatalysts for electrocatalytic evolution of oxygen gas

    Indian Academy of Sciences (India)

    Jahan Bakhsh Raoof; Fereshteh Chekin; Vahid Ehsani

    2015-02-01

    A simple procedure was developed to prepare cobalt oxide nanoparticles (nano-CoO) on multiwall carbon nanotube-modified glassy carbon electrode (MWNT/GCE). Scanning electron microscopy revealed the electrodeposition of nano-CoO with an average particle size of 25 nm onto MWNT/GCE. Also, the presence of nano-CoO was revealed by energy dispersive X-ray spectra. The electrocatalytic activity of nano-CoO and MWNT composite-modified GCE (CoO–MWNT/GCE) has been examined towards the oxygen evolution reaction (OER) by linear sweep voltammetry. The OER is significantly enhanced at CoO–MWNT/GCE, as demonstrated by a negative shift in the polarization curves at the CoO–MWNT/GCE compared with that obtained at the CoO–GCE and GCE. Optimization of the operating experimental conditions (i.e., solution pH and loading level of nano-CoO) has been achieved to maximize the electrocatalytic activity of CoO–MWNT/GCE. The maximum electrocatalytic activity towards the OER was obtained in alkaline media (pH = 13). The electrocatalytic activity of CoO–MWNT/GCE increased with the number of potential cycles employed for the CoO deposition till a certain loading (20 cycles) beyond which an adverse effect is observed. The fabricated CoO–MWNT/GCE exhibited a good stability and durability. The value of energy saving per gram of oxygen gas at a current density of 10 mA cm-2 is 19.3 kWh kg-1.

  19. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small si

  20. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium

    Energy Technology Data Exchange (ETDEWEB)

    Afkhami, Abbas, E-mail: afkhami@basu.ac.ir; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-02-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03–200 μmol L{sup −1}. The lower detection limits were found to be 0.02 μmol L{sup −1}. The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility. - Highlights: • GCE was modified with multiwalled carbon nanotube and gold nanoparticles. • AuNP/MWCNT/GCE was used for the determination of diclofenac sodium. • Modified electrode was characterized by SEM, EDS and EIS. • The proposed method showed excellent analytical figures of merit. • This sensor was used for the determination of diclofenac sodium in real samples.

  1. Synthesis of carbon nanotubes.

    Science.gov (United States)

    Awasthi, Kalpana; Srivastava, Anchal; Srivastava, O N

    2005-10-01

    Carbon nanotubes play a fundamental role in the rapidly developing field of nanoscience and nanotechnology because of their unique properties and high potential for applications. In this article, the different synthesis methods of carbon nanotubes (both multi-walled and single-walled) are reviewed. From the industrial point of view, the chemical vapor deposition method has shown advantages over laser vaporization and electric arc discharge methods. This article also presents recent work in the controlled synthesis of carbon nanotubes with ordered architectures. Special carbon nanotube configurations, such as nanocoils, nanohorns, bamboo-shaped and carbon cylinder made up from carbon nanotubes are also discussed.

  2. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium.

    Science.gov (United States)

    Afkhami, Abbas; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-02-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03-200μmolL(-1). The lower detection limits were found to be 0.02μmolL(-1). The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility.

  3. Amperometric sensing of anti-HIV drug zidovudine on Ag nanofilm-multiwalled carbon nanotubes modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Afraz, Ahmadreza

    2014-06-01

    The zidovudine (ZDV) is the first drug approved for the treatment of HIV virus infection. The detection and determination of this drug are very importance in human serum because of its undesirable effects. A new ZDV sensor was fabricated on the basis of nanocomposite of silver nanofilm (Ag-NF) and multiwalled carbon nanotubes (MWCNTs) immobilized on glassy carbon electrode (GCE). The modified electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) techniques. Results showed that the electrodeposited silver has a nanofilm structure and further electrochemical studies showed that the prepared nanocomposite has high electrocatalytic activity and is appropriate for using in sensors. The amperometric technique under optimal conditions is used for the determination of ZDV ranging from 0.1 to 400 ppm (0.37 μM–1.5 mM) with a low detection limit of 0.04 ppm (0.15 μM) (S/N = 3) and good sensitivity. The prepared sensor possessed accurate and rapid response to ZDV and shows an average recovery of 98.6% in real samples. - Highlights: • New anti-HIV drug sensor was fabricated on the basis of nanomaterials composite. • The GCE modified by prepared hydrophilic MWCNT silver nanoparticles. • Silver nanofilm electrodeposited on MWCNT/GCE and characterized by SEM, EDX, CV and LSV • Response of electrode to ZDV was thoroughly investigated by electrochemical techniques.

  4. Carbon nanotubes paste sensor modified with bismuth film for determination of metallic ions in ethanol fuel

    Directory of Open Access Journals (Sweden)

    Felipe Augusto Gorla

    2015-05-01

    Full Text Available In the present study an anodic stripping voltammetric method using a bismuth film modified carbon nanotubes paste electrode for simultaneous determination of metals Zn2+, Cd2+and Pb2+in ethanol fuel is described. The metallic ions were preconcentrated on the bismuth film in the time and deposition potential of 500 s and -1.2 V and the stripping step was carried out by square wave voltammetry (frequency of 15 Hz, pulse amplitude of 25 mV and potential step of 5 mV. Acetate buffer at 0.1 mol L-1concentration and pH 4.5 was used as support electrolyte. The method showed linearity including the analytical blank up to 48.39 ?g L-1 for the metals and the obtained limits of detection were 3.36, 0.32 and 0.47 ?g L-1for Zn2+, Cd2+and Pb2+, respectively. The proposed method was applied in ethanol fuel samples.

  5. Catalytic performance of heteroatom-modified carbon nanotubes in advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    João Restivo; Raquel P. Rocha; Adrián M. T. Silva; José J. M. Órfão; Manuel F. R. Pereira; José L. Figueiredo

    2014-01-01

    Multi-walled carbon nanotubes (CNTs) were submitted to chemical and thermal treatments in or-der to incorporate different heteroatoms on the surface. O-, S-and N-containing groups were suc-cessfully introduced onto the CNTs without significant changes of the textural properties. The cata-lytic activity of these heteroatom-modified CNTs was studied in two liquid phase oxidation pro-cesses:catalytic ozonation and catalytic wet air oxidation (CWAO), using oxalic acid and phenol as model compounds. In both cases, the presence of strongly acidic O-containing groups was found to decrease the catalytic activity of the CNTs. On the other hand, the introduction of S species (mainly sulfonic acids) enhanced the removal rate of the model compounds, particularly in the CWAO of phenol. Additional experiments were performed with a radical scavenger and sodium persulfate, in order to clarify the reaction mechanism. Nitrogen functionalities improve the catalytic performance of the original CNTs, regardless of the process or of the pollutant.

  6. Multifunctional hybrid nanocomposites based on carbon nanotubes and chemically modified graphene

    OpenAIRE

    Bosch Navarro, Concepcion

    2013-01-01

    La Tesis trata del desarrollo de materiales híbridos multifuncionales basados en nanotubos de carbono y grafeno con interés en magnetismo molecular y electrónica molecular This Thesis deals with the chemistry and development of new hybrid multifunctional systems based on carbon nanotubes (CNTs) and graphene (G). To introduce both types of carbon nanoforms a brief historical overview of these systems has been briefly given at the Preface. Next and prior to the presentation of ...

  7. Electrocatalytic oxidation and determination of homocysteine at carbon nanotubes modified paste electrode using dopamine as a mediator

    OpenAIRE

    Mohammadzadeh Safoora; Fouladgar Masoud

    2013-01-01

    A carbon paste electrode modified with multiwall carbon nanotubes (MWCNTPE) was prepared to study the electrocatalytic activity of dopamine (DP) in the presence of homocysteine (HCy) and it was used for determination of HCy. The diffusion coefficient of HCy (D = 6.79×10−6 cm2 s−1), and the kinetic parameters of its oxidation such as electron transfer coefficient (α = 0.46), and rate constant (kh = 7.44×102 dm3 mol-1 s-1) were also determined using electroch...

  8. Determination of Patulin Using Amperometric Tyrosinase Biosensors Based on Electrodes Modified with Carbon Nanotubes and Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    R.M. Varlamova

    2016-06-01

    Full Text Available New amperometric biosensors based on platinum screen printed electrodes modified with multi-walled carbon nanotubes, gold nanoparticles, and immobilized enzyme – tyrosinase have been developed for determination of patulin in the concentrations of 1·10–6 – 8·10–12 mol/L with an error of no more than 0.063. The best conditions for obtaining gold nanoparticles have been chosen. The conditions for immobilization of multi-walled carbon nanotubes and gold nanoparticles on the surface of the planar electrode have been revealed. The conditions for functioning of the proposed biosensors have been identified. The results have been used to control the content of patulin in food products within and lower than the maximum allowable levels.

  9. Carbon-Pt nanoparticles modified TiO2 nanotubes for simultaneous detection of dopamine and uric acid.

    Science.gov (United States)

    Mahshid, Sara; Luo, Shenglian; Yang, Lixia; Mahshid, Sahar Sadat; Askari, Masoud; Dolati, Abolghasem; Cai, Qingyun

    2011-08-01

    The present work describes sensing application of modified TiO2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO2 nanotubes modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents of dopamine and uric acid were linearly related to the concentration over a wide range of 3.5 x 10(-8) M to 1 x 10(-5) M and 1 x 10(-7) M to 3 x 10(-5) M respectively. The limit of detection was determined as 2 x 10(-10) M for dopamine at signal-to-noise ratio of 3. The interference of uric acid was also investigated. Electro-oxidation currents of dopamine in the presence of fix amount of uric acid represented a linear behaviour towards successive addition of dopamine in range of 1 x 10(-7) M to 1 x 10(-5) M. Furthermore, in a solution containing dopamine, uric acid and ascorbic acid the overlapped oxidation peaks of dopamine and ascorbic acid could be easily separated by using C-Pt-TiO2 nanotubes modified electrode.

  10. Determination of oleuropein using multiwalled carbon nanotube modified glassy carbon electrode by adsorptive stripping square wave voltammetry.

    Science.gov (United States)

    Cittan, Mustafa; Koçak, Süleyman; Çelik, Ali; Dost, Kenan

    2016-10-01

    A multi-walled carbon nanotube modified glassy carbon electrode was used to prepare an electrochemical sensing platform for the determination of oleuropein. Results showed that, the accumulation of oleuropein on the prepared electrode takes place with the adsorption process. Electrochemical behavior of oleuropein was studied by using cyclic voltammetry. Compared to the bare GCE, the oxidation peak current of oleuropein increased about 340 times at MWCNT/GCE. Voltammetric determination of oleuropein on the surface of prepared electrode was studied using square wave voltammetry where the oxidation peak current of oleuropein was measured as an analytical signal. A calibration curve of oleuropein was performed between 0.01 and 0.70µM and a good linearity was obtained with a correlation coefficient of 0.9984. Detection and quantification limits of the method were obtained as 2.73 and 9.09nM, respectively. In addition, intra-day and inter-day precision studies indicated that the voltammetric method was sufficiently repeatable. Finally, the proposed electrochemical sensor was successfully applied to the determination of oleuropein in an olive leaf extract. Microwave-assisted extraction of oleuropein had good recovery values between 92% and 98%. The results obtained with the proposed electrochemical sensor were compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

  11. Amperometric uric acid biosensor based on poly(vinylferrocene)-gelatin-carboxylated multiwalled carbon nanotube modified glassy carbon electrode.

    Science.gov (United States)

    Erden, Pınar Esra; Kaçar, Ceren; Öztürk, Funda; Kılıç, Esma

    2015-03-01

    In this study, a new uric acid biosensor was constructed based on ferrocene containing polymer poly(vinylferrocene) (PVF), carboxylated multiwalled carbon nanotubes (c-MWCNT) and gelatin (GEL) modified glassy carbon electrode (GCE). Uricase enzyme (UOx) was immobilized covalently through N-ethyl-N'-(3-dimethyaminopropyl) carbodiimide (EDC) and N-hydroxyl succinimide (NHS) chemistry onto c-MWCNT/GEL/PVF/GCE. The c-MWCNT/GEL/PVF composite was characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Various experimental parameters such as pH, applied potential, enzyme loading, PVF and c-MWCNT concentration were investigated in detail. Under the optimal conditions the dynamic linear range of uric acid was 2.0×10(-7) M-7.1×10(-4) M (R=0.9993) with the detection limit low to 2.3×10(-8) M. With good selectivity and sensitivity, the biosensor was successfully applied to determine the uric acid in human serum. The results of the biosensor were in good agreement with those obtained from standard method. Therefore, the presented biosensor could be a good promise for practical applications in real samples.

  12. Synergistic effect of plasma-modified halloysite nanotubes and carbon black in natural rubber-butadiene rubber blend

    NARCIS (Netherlands)

    Poikelispaa, Minna; Das, Amit; Dierkes, Wilma; Vuorinen, Jyrki

    2013-01-01

    Halloysite nanotubes (HNTs) were investigated concerning their suitability for rubber reinforcement. As they have geometrical similarity with carbon nanotubes, they were expected to impart a significant reinforcement effect on the rubber compounds but the dispersion of the nanofillers is difficult.

  13. Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine

    Institute of Scientific and Technical Information of China (English)

    Xiao-ping HONG; Yah ZHU; Yan-zhen ZHANG

    2012-01-01

    A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(CoⅡTAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described.This electrode showed a very attractive performance by combining the advantages of Co11TAPc,MWCNTs,and Nafion.Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode,the electrocatalytic activity of poly(CoⅡTAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential,high current responses,and good anti-fouling performance.The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L.

  14. Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

    Science.gov (United States)

    Stiebra, L.; Cabulis, U.; Knite, M.

    2016-04-01

    In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples - 200 ± 10 kg/m3. Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated.

  15. Attachment of Gold Nanoparticles to Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng MA; Ning LUN; Shu Lin WEN

    2005-01-01

    Carbon nanotubes were initially chemically modified with an H2SO4-HNO3 treatment,and subsequently activated with Pd-Sn catalytic nuclei via a one-step activation approach. These activated nanotubes were used as precursors for obtaining gold nanoparticles-attached nanotubes via simple electroless plating. This approach provides an efficient method for attachment of metal nanostructures to carbon nanotubes. Such novel hybrid nanostructures are attractive for many applications.

  16. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    OpenAIRE

    Hayati Filik; Asiye Aslıhan Avan; Sevda Aydar

    2016-01-01

    In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs) were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified e...

  17. Synergic effect of multi-walled carbon nanotubes and gold nanoparticles towards immunosensing of ricin with carbon nanotube-gold nanoparticles-chitosan modified screen printed electrode.

    Science.gov (United States)

    Suresh, Srinivasan; Gupta, Manish; Kumar, Gupta Ajay; Rao, Vepa Kameswara; Kumar, Om; Ghosal, Partha

    2012-09-07

    An amperometric immunosensor for the specific detection of Ricinus communis is reported. Screen printed electrodes (SPEs) were modified with gold nanoparticles (GNPs) loaded multiwalled carbon nanotubes (MWCNTs)-chitosan (Ch) film. The ratio of MWCNT and GNP was optimised to get best electrochemically active electrode. Sandwich immunoassay format was used for the immunosensing of ricin. The revealing antibodies tagged with the enzyme alkaline phosphatase (ALP) converts the substrate 1-naphthyl phosphate into 1-naphthol that was determined with the amperometric technique. The amperometric current obtained was correlated with the concentration of ricin. The prepared GNP-MWCNT-Ch-SPE showed high stability due to the Ch film, short response time with good reproducibility and increased shelf life of the electrodes immobilised with antibodies. The electrochemical activity of the electrode improved because of optimization of composition of CNTs and gold nanoparticles. Under the optimal conditions, the modified electrode showed a wide linear response to the concentration of ricin in the range of 2.5-25 ng mL(-1) with a limit of detection of 2.1 ng mL(-1) and with a relative standard deviation of 5.1% and storage life of 32 days.

  18. Modified Sol-Gel Synthesis of Carbon Nanotubes Supported Titania Composites with Enhanced Visible Light Induced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Quanjie Wang

    2016-01-01

    Full Text Available Multiwalled carbon nanotube (MWCNT enhanced MWCNT/TiO2 nanocomposites were synthesized by surface coating of carbon nanotube with mixed phase of anatase and rutile TiO2 through a modified sol-gel approach using tetrabutyl titanate as raw material. The morphological structures and physicochemical properties of the nanocomposites were characterized by FT-IR, XRD, DTA-TG, TEM, and UV-Vis spectra. The results show that TiO2 nanoparticles with size of around 15 nm are closely attached on the sidewall of MWCNT. The nanocomposites possess good absorption properties not only in the ultraviolet but also in the visible light region. Under irradiation of ultraviolet lamp, the prepared composites have the highest photodegradation efficiency of 83% within 4 hours towards the degradation of Methyl Orange (MO aqueous solution. The results indicate that the carbon nanotubes supported TiO2 nanocomposites exhibit high photocatalytic activity and stability, showing great potentials in the treatment of wastewater.

  19. Carbon nanotube filled with magnetic iron oxide and modified with polyamidoamine dendrimers for immobilizing lipase toward application in biodiesel production

    Science.gov (United States)

    Fan, Yanli; Su, Feng; Li, Kai; Ke, Caixia; Yan, Yunjun

    2017-01-01

    Superparamagnetic multi-walled carbon nanotubes (mMWCNTs) were prepared by filling multi-walled carbon nanotubes (MWCNTs) with iron oxide, and further modified by linking polyamidoamine (PAMAM) dendrimers (mMWCNTs-PAMAM) on the surface. Then, mMWCNTs-PAMAM was employed as the carrier and successfully immobilized Burkholderia cepacia lipase (BCL) via a covalent method (BCL-mMWCNTs-G3). The maximum activity recovery of the immobilized lipase was 1,716% and the specific activity increased to 77,460 U/g-protein, 17-fold higher than that of the free enzyme. The immobilized lipase displayed significantly enhanced thermostability and pH-resistance, and could efficiently catalyze transesterification to produce biodiesel at a conversion rate of 92.8%. Moreover, it possessed better recycling performance. After 20 cycles of repeated used, it still retained ca. 90% of its original activity, since the carbon nanotube−enzyme conjugates could be easily separated from the reaction mixture by using a magnet. This study provides a new perspective for biotechnological applications by adding a magnetic property to the unique intrinsic properties of nanotubes. PMID:28358395

  20. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  1. Simultaneous electrochemical determination of dopamine and paracetamol on multiwalled carbon nanotubes/graphene oxide nanocomposite-modified glassy carbon electrode.

    Science.gov (United States)

    Cheemalapati, Srikanth; Palanisamy, Selvakumar; Mani, Veerappan; Chen, Shen-Ming

    2013-12-15

    In the present study, multiwalled carbon nanotubes (MWCNT)/graphene oxide (GO) nanocomposite was prepared by homogenous dispersion of MWCNT and GO and used for the simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA). The TEM results confirmed that MWCNT walls were wrapped well with GO sheets. The MWCNT/GO nanocomposite showed superior electrocatalytic activity towards the oxidation of DA and PA, when compared with either pristine MWCNT or GO. The major reason for the efficient simultaneous detection of DA and PA at nanocomposite was the synergistic effect between MWCNT and GO. The electrochemical oxidation of DA and PA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The nanocomposite modified electrode showed electrocatalytic oxidation of DA and PA in the linear response range from 0.2 to 400 µmol L(-1) and 0.5 to 400 µmol L(-1) with the detection limit of 22 nmol L(-1) and 47 nmol L(-1) respectively. The proposed sensor displayed good selectivity, sensitivity, stability with appreciable consistency and precision.

  2. Influence of Organo-Modified Laponite on the Percolation Behavior of the Systems Based on Polyethylene Glycol and Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    E.A. Lysenkov

    2016-11-01

    Full Text Available The electric properties of the systems based on polyethylene glycol (PEG, carbon nanotubes (CNT and laponite is studied using methods of impedance spectroscopy and optical microscopy. It is rotined that at introduction to the system of organo-modified laponite (OLP leads to the shift of the percolation threshold to the area of lower concentrations of CNT. The modeling of impedance spectrums by the method of equivalent circuits is conducted for the systems based on PEG. It is set that the introduction of OLP more than 0,4 % in the system results in the considerable decrease of electrical conductivity. This effect is explained that the platelets of OLP hinder the formation of direct contacts between nanotubes.

  3. Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory.

    Science.gov (United States)

    Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi

    2013-01-01

    The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.

  4. Simultaneous determination of cysteamine and folic acid in pharmaceutical and biological samples using modified multiwall carbon nanotube paste electrode

    Institute of Scientific and Technical Information of China (English)

    Ali Taherkhani; Hassan Karimi-Maleh; Ali A.Ensafi; Hadi Beitollahi; Ahmad Hosseini; Mohammad A.Khalilzadeh; Hassan Bagheri

    2012-01-01

    A carbon paste electrode (CPE) chemically modified with multiwall carbon nanotubes and ferrocene (FC) was used as a selective electrochemical sensor for the simultaneous determination of trace amounts of cysteamine (CA) and folic acid (FA).This modified electrode showed very efficient electrocatalytic activity for the anodic oxidation of CA.The peak current of differential pulse voltammograms of CA and FA increased linearly with their concentration in the ranges of 0.7-200 μmol/L CA and 5.0-700 μmol/L FA.The detection limits for CA and FA were 0.3 μmol/L and 2.0 μ mol/L,respectively.The diffusion coefficient (D) and transfer coefficient (α) of CA were also determined.These conditions are sufficient to allow determination of CA and FA both individually and simultaneously.

  5. Carbon nanotube embedded poly 1,5-diaminonapthalene modified pyrolytic graphite sensor for the determination of sulfacetamide in pharmaceutical formulations.

    Science.gov (United States)

    Yadav, Saurabh K; Choubey, Pravir K; Agrawal, Bharati; Goyal, Rajendra N

    2014-01-01

    An electrochemically conductive single-walled carbon nanotube (SWCNT) embedded poly 1,5-diaminonapthalene (DAN) modified sensor has been developed for the determination of sulfacetamide (SFA). The surface morphology of the modified sensor has been characterized by FE-SEM, which revealed good dispersion of the carbon nanotube in polymer matrix. SFA was quantified using square wave voltammetry in phosphate buffer of pH 7.2, which acted as supporting electrolyte during analysis. The modified sensor exhibited an effective catalytic response towards the oxidation of SFA with excellent reproducibility and stability. The peak current of SFA was found to be linear in the concentration range of 0.005-1.5 mM and detection limit and sensitivity of 0.11 μM (S/N=3) and 23.977 µA mM(-1), respectively were observed. The analytical utility of method was checked by determining the SFA in various pharmacological dosage forms. The results obtained from the voltammetry were validated by comparing the results with those obtained from HPLC. The proposed method is sensitive, simple, rapid and reliable and is useful for the routine analysis of SFA in pharmaceutical laboratories.

  6. Analysis of polyphenols in white wine by CZE with amperometric detection using carbon nanotube-modified electrodes.

    Science.gov (United States)

    Moreno, Mónica; Arribas, Alberto Sánchez; Bermejo, Esperanza; Zapardiel, Antonio; Chicharro, Manuel

    2011-04-01

    A method for the simultaneous detection of five polyphenols (caffeic, chlorogenic, ferulic and gallic acids and (+)-catechin) by CZE with electrochemical detection was developed. Separation of these polyphenols was performed in a 100 mM borate buffer (pH 9.2) within 15 min. Under optimized separation conditions, the performance of glassy carbon (GC) electrodes modified with multiwalled carbon nanotube layer obtained from different dispersions was examined. GC electrode modified with a dispersion of multi-walled carbon nanotubes (CNT) in polyethylenimine has proven to be the most suitable CNT-based electrode for its application as amperometric detector for the CZE separation of the studied compounds. The excellent electrochemical properties of this electrode allowed the detection of the selected polyphenols at +200 mV and improved the efficiency and the resolution of their CZE separation. Limits of detection below 3.1 μM were obtained with linear ranges covering the 10⁻⁵ to 10⁻⁴  M range. The proposed method has been successfully applied for the detection (ferulic, caffeic and gallic acids and (+)-catechin) and the quantification (gallic acid and (+)-catechin) of polyphenols in two different white wines without any preconcentration step. A remarkable signal stability was observed on the electrode performance despite the presence of potential fouling substances in wine.

  7. Electrocatalytic oxidation and determination of homocysteine at carbon nanotubes modified paste electrode using dopamine as a mediator

    Directory of Open Access Journals (Sweden)

    Mohammadzadeh Safoora

    2013-01-01

    Full Text Available A carbon paste electrode modified with multiwall carbon nanotubes (MWCNTPE was prepared to study the electrocatalytic activity of dopamine (DP in the presence of homocysteine (HCy and it was used for determination of HCy. The diffusion coefficient of HCy (D = 6.79×10−6 cm2 s−1, and the kinetic parameters of its oxidation such as electron transfer coefficient (α = 0.46, and rate constant (kh = 7.44×102 dm3 mol-1 s-1 were also determined using electrochemical approaches. Under the optimum pH of 5.0, the peak current of oxidation of HCy at MWCNTPE in the presence of DP occurs at a potential about 530 mV and the results showed that the oxidation peak current of HCy at the modified carbon nanotubes electrode was higher than on unmodified electrode. The peak current of differential pulse voltammograms of HCy solutions increased linearly in the range of 3.0-600.0 μM HCy with the detection limit of 2.08 μM HCy. This method was also examined for determination of HCy in physiological serum and urine samples.

  8. Internal length parameter and buckling analysis of carbon nanotubes using modified couple stress theory and Timoshenko beam model

    Science.gov (United States)

    Khajueenejad, F.; Ghanbari, J.

    2015-10-01

    The internal length parameter of the modified couple stress theory for single walled carbon nanotubes (CNTs) is determined in this paper. Buckling of CNTs have been studied using Timoshenko beam model and modified couple stress theory. The governing equations for three different end conditions, simple-simple, clamped-clamped and clamped-free, are solved using variational methods and an exact solution is provided for the buckling load. The effects of the internal length parameter on the buckling load of various CNT length and diameters are studied. It is observed that the internal length parameter has larger influence on the higher modes of buckling and for shorter nanotubes. A method presented to obtain the internal length parameter of higher order theories. By correlating the obtained results with the more accurate molecular dynamics simulations, the internal length parameter has been calculated for zigzag and armchair nanotubes. It is observed that the internal length parameter has slight dependency on the size of the CNTs and an average value is provided.

  9. Phosphate-modified carbon nanotubes in the oxidative dehydrogenation of isopentanes.

    Science.gov (United States)

    Huang, Rui; Liu, Hong Yang; Zhang, Bing Sen; Sun, Xiao Yan; Liang, Chang Hai; Su, Dang Sheng; Zong, Bao Ning; Rong, Jun Feng

    2014-12-01

    Ketonic/quinonic C=O groups on the surface of a carbon matrix are capable of abstracting hydrogen in C=H bonds from hydrocarbons and enable them to selectively convert into corresponding unsaturated hydrocarbons; this process is the oxidative dehydrogenation (ODH) reaction. However, a variety of inevitable defects or graphene edges and other oxygen-containing groups on the carbon matrix are detrimental to the selective production of alkenes due to their high activity towards overoxidation. Herein, we show that phosphate can not only impede the total oxidation but also cover the selective C=O groups, hence allowing its use as a modulator to defects and oxygen-containing functional groups on the multiwalled carbon nanotubes, regulating the distribution of active sites and related catalytic targets.

  10. Chemiresistive sensor based on polythiophene-modified single-walled carbon nanotubes for detection of NO2

    Science.gov (United States)

    Gaikwad, Sumedh; Bodkhe, Gajanan; Deshmukh, Megha; Patil, Harshada; Rushi, Arti; Shirsat, Mahendra D.; Koinkar, Pankaj; Kim, Yun-Hae; Mulchandani, Ashok

    2015-03-01

    In the present investigation, a chemiresistive sensor based on conducting polythiophene-modified single-walled carbon nanotubes (SWNTs) for NO2 detection has been reported. The SWNTs were aligned across 3 μm gap between two gold microelectrodes on Si/SiO2 substrate. Alignment of SWNTs was carried out by using AC dielectrophoretic technique and it was confirmed by current-voltage (I-V) measurement. Aligned SWNTs were modified by conducting polythiophene using charge controlled potentiostatic deposition and it was confirmed by field-effect transistor (FET) and electrochemical measurements. Polythiophene-modified SWNT devices were used for the NO2 detection in chemiresistive modality. This sensor exhibited very good linear response range from 10 ppb to 10 ppm.

  11. Reinforcement of semicrystalline polymers with collagen-modified single walled carbon nanotubes

    Science.gov (United States)

    Bhattacharyya, Sanjib; Salvetat, Jean-Paul; Saboungi, Marie-Louise

    2006-06-01

    We report on the enhancement of the mechanical properties of single wall carbon nanotube (SWNT)-polyvinyl alcohol (PVA) composites through functionalization of SWNTs with denatured collagen. In addition to improving compatibility with the matrix, the denatured collagen layer was found to increase the PVA matrix crystallinity, which results in a dramatic enhancement of the Young's modulus (260%), tensile strength (300%), and toughness (700%) well above what can be expected with the classical rule of mixture. A supramolecular organization at the interface is associated with an increase of PVA crystallinity as shown by the x-ray diffraction and differential scanning calorimetry.

  12. Adsorption of carbon dioxide on amine-modified TiO2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    Fujiao Song; Yunxia Zhao; Qin Zhong

    2013-01-01

    TiO2 nanotubes (TiNT) were prepared by a hydrothermal treatment and modified by three kinds of amines,namely ethylenediamine,polyetherimide and tetraethylenepentamine (TEPA),to study their CO2 adsorption properties from gas streams.The resultant samples were characterized by X-ray diffraction,transmission electron microscopy,and infrared spectroscopy,as well as low temperature N2adsorption.CO2 capture was investigated in a dynamic packed column at 30℃.TEPA-modified TiO2 nanotubes showed the highest adsorption capacity of 167.64 mg/g because it had the highest amino-group content among the three amines.CO2 fixation on TiNT impregnated by TEPA was investigated at 30,50,and 70℃C,and the adsorption capacity increased slightly with temperature.Following the adsorption step,the sorbents were regenerated by temperature programmed desorption,and the TiNT-TEPA sample,as CO2 sorbent,was found to be readily regenerated and energy-efficient.The cycle test also revealed that the TiNT-TEPA adsorbent is fairly stable,with only a 5% drop in the adsorption capacity after 10 adsorption/desorption cycles.In addition,the CO2 adsorption behavior was investigated with the deactivation model,and which showed an excellent prediction for the TiNT-TEPA breakthrough curves.

  13. Analytical applications of a carbon nanotubes composite modified with copper microparticles as detector in flow systems.

    Science.gov (United States)

    Arribas, Alberto Sánchez; Bermejo, Esperanza; Chicharro, Manuel; Zapardiel, Antonio; Luque, Guillermina L; Ferreyra, Nancy F; Rivas, Gustavo A

    2006-09-08

    In this work we report on the successful use of a composite prepared by dispersion of multi-wall carbon nanotubes (1-5 microm length, 20-50 nm diameter) and copper microparticles within mineral oil as detector for amino acids quantification in flow injection analysis and capillary electrophoresis. The resulting electrode displays a highly sensitive amperometric detection of amino acids, based on the copper dissolution facilitated by the strong activity of amino acids as ligands of Cu(II). The sensor makes possible the detection of amino acids, electroactive or not, at very low potentials (0.000 V) and physiological pH. A correlation between the sensitivity for the amino acids and the amount of copper within the composite is observed, demonstrating the importance of the metal in the sensor response. The best analytical performance is obtained for the electrode containing 12.0% (w/w) copper. The excellent results obtained with the carbon nanotube paste electrodes containing copper (CNTPE-Cu) as detector in flow systems makes them an interesting alternative for further analytical applications involving different bioanalytes.

  14. Facile fabrication of robust superhydrophobic multilayered film based on bioinspired poly(dopamine)-modified carbon nanotubes.

    Science.gov (United States)

    Wang, Jin-lei; Ren, Ke-feng; Chang, Hao; Zhang, Shi-miao; Jin, Lie-jiang; Ji, Jian

    2014-02-21

    Thin organic films containing carbon nanotubes (CNTs) have received increasing attention in many fields. In this study, a robust thin superhydrophobic film has been created by using layer-by-layer assembly of the carbon nanotubes wrapped by poly(dopamine) (CNT@PDA) and poly(ethyleneimine) (PEI). UV-vis spectroscopy, ellipsometry, and quartz crystal microbalance with dissipation (QCM-D) measurements confirmed that the sequential deposition of PEI and CNT@PDA resulted in a linear growth of the (PEI-CNT@PDA) film. This thin film contained as much as 77 wt% CNTs. Moreover, a very stable and flexible free-standing (PEI-CNT@PDA) film could be obtained by employing cellulose acetate (CA) as a sacrificial layer. The film could even withstand ultrasonication in saturated SDS aqueous solution for 30 min. SEM observations indicated that the ultrathin film consisted of nanoscale interpenetrating networks of entangled CNTs and exhibited a very rough surface morphology. The (PEI-CNT@PDA) film turned superhydrophobic after being coated with a low-surface-energy compound. The superhydrophobic films showed excellent resistance against the adhesion of both platelets and Escherichia coli (E. coli). The (PEI-CNT@PDA) films and the proposed methodology may find applications in the area of medical devices to reduce device-associated thrombosis and infection.

  15. LDRD final report on carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  16. High-Flux Positively Charged Nanocomposite Nanofiltration Membranes Filled with Poly(dopamine) Modified Multiwall Carbon Nanotubes.

    Science.gov (United States)

    Zhao, Feng-Yang; Ji, Yan-Li; Weng, Xiao-Dan; Mi, Yi-Fang; Ye, Chun-Chun; An, Quan-Fu; Gao, Cong-Jie

    2016-03-01

    The poor dispensability of pristine carbon nanotubes in water impedes their implications in thin-film nanocomposite membranes for crucial utilities such as water purification. In this work, high-flux positively charged nanocomposite nanofiltration membranes were exploited by uniformly embedding poly(dopamine) modified multiwall carbon nanotubes (PDA-MWCNTs) in polyamide thin-film composite membranes. With poly(dopamine) modification, fine dispersion of MWCNTs in polyethyleneimine (PEI) aqueous solutions was achieved, which was interracially polymerized with trimesoyl chloride (TMC) n-hexane solutions to prepare nanocomposite membranes. The compatibility and interactions between modified MWCNTs and polyamide matrix were enhanced, attributed to the poly(dopamine) coatings on MWCNT surfaces, leading to significantly improved water permeability. At optimized conditions, pure water permeability of the PEI/PDA-MWCNTs/TMC nanofiltration membrane (M-4) was 15.32 L m(-2) h(-1) bar(-1), which was ∼1.6 times increased compared with that of pristine PEI/TMC membranes. Salt rejection of M-4 to different multivalent cations decreased in the sequence ZnCl2 (93.0%) > MgCl2 (91.5%) > CuCl2 (90.5%) ≈ CaCl2, which is well-suited for water softening and heavy metal ion removal.

  17. Modification of carbon nanotubes and synthesis of polymeric composites involving the nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Badamshina, E R; Gafurova, M P; Estrin, Yakov I [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2010-12-29

    The results of studies, mainly published in recent years, on modification of carbon nanotubes and design of composites with these nanotubes for the manufacture of new-generation materials are generalized and analyzed. The methods of modification of the nanotubes by low- and high-molecular compounds and methods of polymer modification by carbon nanotubes are considered. Data on the properties of modified nanotubes are presented. The current and potential applications of materials based on the nanotubes are indicated.

  18. Nanomechanics of carbon nanotubes.

    Science.gov (United States)

    Kis, Andras; Zettl, Alex

    2008-05-13

    Some of the most important potential applications of carbon nanotubes are related to their mechanical properties. Stiff sp2 bonds result in a Young's modulus close to that of diamond, while the relatively weak van der Waals interaction between the graphitic shells acts as a form of lubrication. Previous characterization of the mechanical properties of nanotubes includes a rich variety of experiments involving mechanical deformation of nanotubes using scanning probe microscopes. These results have led to promising prototypes of nanoelectromechanical devices such as high-performance nanomotors, switches and oscillators based on carbon nanotubes.

  19. Electrochemical detection of hydrogen peroxide at a waxed graphite electrode modified with platinum-decorated carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    SHI Qiao-cui; ZENG Wen-fang; ZHU Yunu

    2009-01-01

    Platinum-decorated carbon nanotubes (CNT-Pt) were produced by the chemical reduction method. A novel modified electrode was fabricated by intercalated CNT-Pt in the surface of waxed graphite, which provided excellent electro-catalytic activity and selectivity for both oxidation and reduction of hydrogen peroxide. The current response of the modified electrode for hydrogen peroxide was very rapid and the detection limits in amperometry are 2.5×10-6 mol/L at reduction potential and 4.8×10-6 mol/L at oxidation potential. It was desmonstrated that the electrode with high electro-activity was a suitable basic electrode for preparing enzyme electrode.

  20. Overoxidized polypyrrole/multi-walled carbon nanotubes composite modified electrode for in vivo liquid chromatography-electrochemical detection of dopamine.

    Science.gov (United States)

    Wen, Jingxia; Zhou, Li; Jin, Litong; Cao, Xuni; Ye, Bang-Ce

    2009-07-01

    Overoxidized polypyrrole/multi-walled carbon nanotubes (OPPy/MWNTs) modified electrode has been developed for sensitively detecting dopamine (DA). OPPy films developed outside MWNTs might have a porous morphology. Thus, OPPy/MWNTs films developed by this method do not reject ascorbic acid (AA). However, OPPy/MWNTs modified electrode shows largely enhancing oxidative current responses of DA. When combined with liquid chromatography, it not only obtains a low detection limit of 7.5 x 10(-10) mol L(-1) for DA, but also improves the selectivity of DA detection. Mechanisms for the enhancement are also well discussed in this paper. With this approach, microdialysis has been employed for successful assessment of DA in rat striatum.

  1. Glucose biosensor based on a glassy carbon electrode modified with polythionine and multiwalled carbon nanotubes.

    Directory of Open Access Journals (Sweden)

    Wenwei Tang

    Full Text Available A novel glucose biosensor was fabricated. The first layer of the biosensor was polythionine, which was formed by the electrochemical polymerisation of the thionine monomer on a glassy carbon electrode. The remaining layers were coated with chitosan-MWCNTs, GOx, and the chitosan-PTFE film in sequence. The MWCNTs embedded in FAD were like "conductive wires" connecting FAD with electrode, reduced the distance between them and were propitious to fast direct electron transfer. Combining with good electrical conductivity of PTH and MWCNTs, the current response was enlarged. The sensor was a parallel multi-component reaction system (PMRS and excellent electrocatalytic performance for glucose could be obtained without a mediator. The glucose sensor had a working voltage of -0.42 V, an optimum working temperature of 25°C, an optimum working pH of 7.0, and the best percentage of polytetrafluoroethylene emulsion (PTFE in the outer composite film was 2%. Under the optimised conditions, the biosensor displayed a high sensitivity of 2.80 µA mM(-1 cm(-2 and a low detection limit of 5 µM (S/N = 3, with a response time of less than 15 s and a linear range of 0.04 mM to 2.5 mM. Furthermore, the fabricated biosensor had a good selectivity, reproducibility, and long-term stability, indicating that the novel CTS+PTFE/GOx/MWCNTs/PTH composite is a promising material for immobilization of biomolecules and fabrication of third generation biosensors.

  2. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

    Energy Technology Data Exchange (ETDEWEB)

    Li Xinchun [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Chen Zuanguang, E-mail: chenzg@mail.sysu.edu.cn [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Zhong Yuwen, E-mail: yu0106@163.com [Center for Disease Control and Prevention of Guangdong Province, 176 Xingangxi, Guangzhou 510300 (China); Yang Fan; Pan Jianbin; Liang Yajing [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. Black-Right-Pointing-Pointer Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. Black-Right-Pointing-Pointer An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. Black-Right-Pointing-Pointer Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 {mu}M (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and

  3. Growth of Ag nanoparticles using plasma-modified multi-walled carbon nanotubes.

    Science.gov (United States)

    Tseng, Chun-Hao; Chen, Chuh-Yung

    2008-01-23

    This study presents a novel method for preparing multi-walled carbon nanotubes (MWNTs) grafted with a poly(2-hydroxyethyl methacrylate) (HEMA)-silver complex (CNTs-HEMA-Ag complex) through plasma-induced grafting polymerization. The characteristics of the MWNTs after being grafted with HEMA polymer are monitored by Fourier transform infrared (FT-IR) spectroscopy. The chelating groups in the HEMA polymer grafted on the surface of the CNTs-HEMA are the coordination sites for chelating silver ions, and are further used as nanotemplates for the growing of Ag nanoparticles (quantum dots). Transmission electron microscopy (TEM) reveals that the particle size of Ag nanoparticles on the CNT surfaces increases with the Ag(+) chelating concentration, reaction time, and reaction temperature. Moreover, the crystalline phase of Ag nanoparticles is identified by using x-ray diffraction (XRD). In addition, high-resolution x-ray photoelectron spectroscopy (XPS) is used to characterize the functional groups on the surface of the MWNTs after chemical modification through plasma treatment; it demonstrates that the growing amount of the Ag nanoparticles on the nanotubes increases with the Ag(+) chelating concentration due to the blocking effect of the Ag particles forming on the MWNTs.

  4. Direct electrochemistry and electrochemical catalysis of myoglobin-TiO2 coated multiwalled carbon nanotubes modified electrode.

    Science.gov (United States)

    Zhang, Lei; Tian, Dan-Bi; Zhu, Jun-Jie

    2008-11-01

    TiO(2) nanoparticles were homogeneously coated on multiwalled carbon nanotubes (MWCNTs) by hydrothermal deposition, and this nanocomposite might be a promising material for myoglobin (Mb) immobilization in view of its high biocompatibility and large surface. The glassy carbon (GC) electrode modified with Mb-TiO(2)/MWCNTs films exhibited a pair of well-defined, stable and nearly reversible cycle voltammetric peaks. The formal potential of Mb in TiO(2)/MWCNTs film was linearly varied in the range of pH 3-10 with a slope of 48.65 mV/pH, indicating that the electron transfer was accompanied by single proton transportation. The electron transfer between Mb and electrode surface, k(s) of 3.08 s(-1), was greatly facilitated in the TiO(2)/MWCNTs film. The electrocatalytic reductions of hydrogen peroxide were also studied, and the apparent Michaelis-Menten constant is calculated to be 83.10 microM, which shows a large catalytic activity of Mb in the TiO(2)/MWCNTs film to H(2)O(2). The modified GC electrode shows good analytical performance for amperometric determination of hydrogen peroxide. The resultant Mb-TiO(2)/MWCNTs modified glassy carbon electrode exhibited fast amperometric response to hydrogen peroxide reduction, long term life and excellent stability. Finally the activity of the sensor for nitric oxide reduction was also investigated.

  5. Assembly of Modified Ferritin Proteins on Carbon Nanotubes and its Electrocatalytic Activity for Oxygen Reduction

    Science.gov (United States)

    Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol

    2012-01-01

    Highly effective dispersions of carbon nanotubes (CNTs) can be made using a commercially available buffer solution. Buffer solutions of 3-(N-morpholino)-propanesulfonic acid (MOPS), which consists of a cyclic ring with nitrogen and oxygen heteroatoms, a charged group, and an alkyl chain greatly enhance the dispersibility and stability of CNTs in aqueous solutions. Additionally, the ability of biomolecules, especially cationized Pt-cored ferritins, to adhere onto the well-dispersed CNTs in the aqueous buffer solution is also improved. This was accomplished without the use of surfactant molecules, which are detrimental to the electrical, mechanical, and other physical properties of the resulting products. The assembled Pt-cored ferritin proteins on the CNTs were used as an electrocatalyst for oxygen reduction

  6. Adsorption on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    DING Yi; YANG Xiao-bao; NI Jun

    2006-01-01

    Adsorption on single walled carbon nanotubes (SWCNTs) is a subject of growing experimental and theoretical interest.The possible adsorbed patterns of atoms and molecules on the single-walled carbon nanotubes vary with the diameters and chirality of the tubes due to the confinement.The curvature of the carbon nanotube surface enlarges the distance of the adsorbate atoms and thus enhances the stability of high coverage structures of adsorbate.There exist two novel high-coverage stable structures of potassium adsorbed on SWCNTs,which are not stable on graphite.The electronic properties of SWCNTs can be modified by adsorbate atoms and metal-semiconductor and semiconductor-semi-conductor transitions can be achieved by the doping of alkali atoms.

  7. Anti-tumor response induced by immunologically modified carbon nanotubes and laser irradiation using rat mammary tumor model

    Science.gov (United States)

    Acquaviva, Joseph T.; Hasanjee, Aamr M.; Bahavar, Cody F.; Zhou, Fefian; Liu, Hong; Howard, Eric W.; Bullen, Liz C.; Silvy, Ricardo P.; Chen, Wei R.

    2015-03-01

    Laser immunotherapy (LIT) is being developed as a treatment modality for metastatic cancer which can destroy primary tumors and induce effective systemic anti-tumor responses by using a targeted treatment approach in conjunction with the use of a novel immunoadjuvant, glycated chitosan (GC). In this study, Non-invasive Laser Immunotherapy (NLIT) was used as the primary treatment mode. We incorporated single-walled carbon nanotubes (SWNTs) into the treatment regimen to boost the tumor-killing effect of LIT. SWNTs and GC were conjugated to create a completely novel, immunologically modified carbon nanotube (SWNT-GC). To determine the efficacy of different laser irradiation durations, 5 minutes or 10 minutes, a series of experiments were performed. Rats were inoculated with DMBA-4 cancer cells, a highly aggressive metastatic cancer cell line. Half of the treatment group of rats receiving laser irradiation for 10 minutes survived without primary or metastatic tumors. The treatment group of rats receiving laser irradiation for 5 minutes had no survivors. Thus, Laser+SWNT-GC treatment with 10 minutes of laser irradiation proved to be effective at reducing tumor size and inducing long-term anti-tumor immunity.

  8. Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties

    Directory of Open Access Journals (Sweden)

    H. F. Xie

    2012-09-01

    Full Text Available Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN. The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg, mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM. DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.

  9. Electroless deposition of bis(4'-(4-Pyridyl)-2,2':6',2''-terpyridine)iron(II) thiocyanate complex onto carbon nanotubes modified glassy carbon electrode: application to simultaneous determination of ascorbic acid, dopamine and uric acid

    OpenAIRE

    Kamyabi,M. A; Narimani,O; Monfared,H. H

    2011-01-01

    A glassy carbon (GC) electrode modified by multi-walled carbon nanotubes (MWNTs) and bis(pyterpy)iron(II) thiocyanate complex (pyterpy = 4'-(4-pyridyl)-2,2':6',2''-terpyridine) was investigated by voltammetric methods in acetate buffer solution (pH 5). Performances of the iron(II)-complex/MWNTs modified electrode were evaluated with differential pulse voltammetry and scanning electron microscopy (SEM). The modified glassy carbon electrode shows an excellent electrochemical response for ascorb...

  10. Magnetic particle-based sandwich sensor with DNA-modified carbon nanotubes as recognition elements for detection of DNA hybridization.

    Science.gov (United States)

    Hu, Po; Huang, Cheng Zhi; Li, Yuan Fang; Ling, Jian; Liu, Yu Ling; Fei, Liang Run; Xie, Jian Ping

    2008-03-01

    In this contribution, we design a visual sensor for DNA hybridization with DNA probe-modified magnetic particles (MPs) and multiwalled carbon nanotubes (MWNTs) without involving a visual recognition element such as fluorescent/chemiluminescent reagents. It was found that DNA probe-modified MWNTs, which could be dispersed in aqueous medium and have strong light scattering signals under the excitation of a light beam in the UV-vis region, could connect with DNA probe-modified MPs together in the presence of perfectly complementary target DNA and form a sandwich structure. In a magnetic field, the formed MP-MWNT species can easily be removed from the solution, resulting in a decrease of light scattering signals. Thus, a magnetic particle-based sandwich sensor could be developed to detect DNA hybridization by measuring the light scattering signals with DNA-modified MWNTs as recognition elements. Experiments showed that the DNA-modified MPs sensor could be reused at least 17 times and was stable for more than 6 months.

  11. Study of Carbon Nanotube-Substrate Interaction

    Directory of Open Access Journals (Sweden)

    Jaqueline S. Soares

    2012-01-01

    Full Text Available Environmental effects are very important in nanoscience and nanotechnology. This work reviews the importance of the substrate in single-wall carbon nanotube properties. Contact with a substrate can modify the nanotube properties, and such interactions have been broadly studied as either a negative aspect or a solution for developing carbon nanotube-based nanotechnologies. This paper discusses both theoretical and experimental studies where the interaction between the carbon nanotubes and the substrate affects the structural, electronic, and vibrational properties of the tubes.

  12. Immobilization of trypsin on water-soluble dendrimer-modified carbon nanotubes for on-plate proteolysis combined with MALDI-MS analysis.

    Science.gov (United States)

    Zhang, Ying; Cao, Weiman; Liu, Minbo; Yang, Shiping; Wu, Huixia; Lu, Haojie; Yang, Pengyuan

    2010-08-01

    A novel on-plate digestion method combined with MALDI-MS analysis is reported, using trypsin-linked dendrimer-modified carbon nanotubes (dCNTs) as the enzyme immobilization probe. Excellent digestion performance was achieved in a short time without any complicated reduction and alkylation procedures.

  13. Liquid composite molding-processing and characterization of fiber-reinforced composites modified with carbon nanotubes

    Science.gov (United States)

    Zeiler, R.; Khalid, U.; Kuttner, C.; Kothmann, M.; Dijkstra, D. J.; Fery, A.; Altstädt, V.

    2014-05-01

    The increasing demand in fiber-reinforced plastics (FRPs) necessitates economic processing of high quality, like the vacuum-assisted resin transfer molding (VARTM) process. FRPs exhibit excellent in-plane properties but weaknesses in off-plane direction. The addition of nanofillers into the resinous matrix phase embodies a promising approach due to benefits of the nano-scaled size of the filler, especially its high surface and interface areas. Carbon nanotubes (CNTs) are preferable candidates for resin modification in regard of their excellent mechanical properties and high aspect ratios. However, especially the high aspect ratios give rise to withholding or filtering by fibrous fabrics during the impregnation process, i.e. length dependent withholding of tubes (short tubes pass through the fabric, while long tubes are restrained) and a decrease in the local CNT content in the laminate along the flow path can occur. In this study, hybrid composites containing endless glass fiber reinforcement and surface functionalized CNTs dispersed in the matrix phase were produced by VARTM. New methodologies for the quantification of the filtering of CNTs were developed and applied to test laminates. As a first step, a method to analyze the CNT length distribution before and after injection was established for thermosetting composites to characterize length dependent withholding of nanotubes. The used glass fiber fabric showed no perceptible length dependent retaining of CNTs. Afterward, the resulting test laminates were examined by Raman spectroscopy and compared to reference samples of known CNT content. This Raman based technique was developed further to assess the quality of the impregnation process and to quantitatively follow the local CNT content along the injection flow in cured composites. A local decline in CNT content of approx. 20% was observed. These methodologies allow for the quality control of the filler content and size-distribution in CNT based hybrid

  14. Hydrogen peroxide sensor based on modified vitreous carbon with multiwall carbon nanotubes and composites of Pt nanoparticles-dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, C.; Orozco, G. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Verde, Y. [Instituto Tecnologico de Cancun, Av. Kabah Km. 3, C.P. 77500, Cancun, Quintana Roo (Mexico); Jimenez, S. [Unidad Queretaro Centro de Investigacion y de Estudios Avanzados del I.P.N., Juriquilla, Santiago de Queretaro (Mexico); Godinez, Luis A. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Juaristi, E. [Chemistry Department, Centro de Investigacion y de Estudios Avanzados del I.P.N., P.O. Box 14-740, C.P. 07360 Mexico, D.F. (Mexico); Bustos, E. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Chemistry Department, Centro de Investigacion y de Estudios Avanzados del I.P.N., P.O. Box 14-740, C.P. 07360 Mexico, D.F. (Mexico)], E-mail: ebustos@cideteq.mx

    2009-02-15

    Sensors using nanostructured materials have been under development in the last decade due to their selectivity for the detection and quantification of different compounds. The physical and chemical characteristics of carbon nanotubes provide significant advantages when used as electrodes for electronic devices, fuel cells and electrochemical sensors. This paper presents preliminary results on the modification of vitreous carbon electrodes with Multiwall Carbon Nanotubes (MWCNTs) and composites of Pt nanoparticles-dopamine (DA) as electro-catalytic materials for the hydrogen peroxide (H{sub 2}O{sub 2}) reaction. Chemical pre-treatment and consequent functionalization of MWCNTs with carboxylic groups was necessary to increase the distribution of the composites. In addition, the presence of DA was important to protect the active sites and eliminate the pasivation of the surface after the electro-oxidation of H{sub 2}O{sub 2} takes place. The proposed H{sub 2}O{sub 2} sensor exhibited a linear response in the 0-5 mM range, with detection and quantification limits of 0.3441 mM and 1.1472 mM, respectively.

  15. Analysis of total polyphenols in wines by FIA with highly stable amperometric detection using carbon nanotube-modified electrodes.

    Science.gov (United States)

    Arribas, Alberto Sánchez; Martínez-Fernández, Marta; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio; Chicharro, Manuel

    2013-02-15

    The use of glassy carbon electrodes (GCEs) modified with multi-walled carbon nanotube (CNT) films for the continuous monitoring of polyphenols in flow systems has been examined. The performance of these modified electrodes was evaluated and compared to bare GCE by cyclic voltammetry experiments and by flow injection analysis (FIA) with amperometric detection monitoring the response of gallic, caffeic, ferulic and p-coumaric acids in 0.050 M acetate buffer pH 4.5 containing 100 mM NaCl. The GCE modified with CNT dispersions in polyethyleneimine (PEI) provided lower overpotentials, higher sensitivity and much higher signal stability under a dynamic regime than bare GCEs. These properties allowed the estimation of the total polyphenol content in red and white wines with a remarkable long-term stability in the measurements despite the presence of potential fouling substances in the wine matrix. In addition, the versatility of the electrochemical methodology allowed the selective estimation of the easily oxidisable polyphenol fraction as well as the total polyphenol content just by tuning the detection potential at +0.30 or 0.70 V, respectively. The significance of the electrochemical results was demonstrated through correlation studies with the results obtained with conventional spectrophotometric assays for polyphenols (Folin-Ciocalteu, absorbance at 280 nm index and colour intensity index).

  16. Simultaneous Electrochemical Determination of Hydroquinone, Catechol and Resorcinol at Nitrogen Doped Porous Carbon Nanopolyhedrons-multiwall Carbon Nanotubes Hybrid Materials Modified Glassy Carbon Electrode

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Wu, Liang; Zhang, Xiaohua; Chen, Jinhua [Hunan Univ., Changsha (China)

    2014-01-15

    The nitrogen doped porous carbon nanopolyhedrons (N-PCNPs)-multi-walled carbon nanotubes (MWCNTs) hybrid materials were prepared for the first time. Combining the excellent catalytic activities, good electrical conductivities and high surface areas of N-PCNPs and MWCNTs, the simultaneous determination of hydroquinone (HQ), catechol (CC) and resorcinol (RE) with good analytical performance was achieved at the N-PCNPs-MWCNTs modified electrode. The linear response ranges for HQ, CC and RE are 0.2-455 μM, 0.7-440 μM and 3.0-365 μM, respectively, and the detection limits (S/N = 3) are 0.03 μM, 0.11 μM and 0.38 μM, respectively. These results are much better than that obtained on some graphene or CNTs-based materials modified electrodes. Furthermore, the developed sensor was successfully applied to simultaneously detect HQ, CC and RE in the local river water samples.

  17. The Application of Nafion Metal Catalyst Free Carbon Nanotube Modified Gold Electrode: Voltammetric Zinc Detection in Serum

    Science.gov (United States)

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2013-01-01

    Metal catalyst free carbon nanotube (MCFCNT) whiskers were first used as an electrode modification material on a gold electrode surface for zinc voltammetric measurements. A composite film of Nafion and MCFCNT whiskers was applied to a gold electrode surface to form a mechanically stable sensor. The sensor was then used for zinc detection in both acetate buffer solution and extracted bovine serum solution. A limit of detection of 53 nM was achieved for a 120 s deposition time. The zinc in bovine serum was extracted via a double extraction procedure using dithizone in chloroform as a zinc chelating ligand. The modified electrode was found to be both reliable and sensitive for zinc measurements in both matrices. PMID:24436574

  18. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  19. Magnetic multiwall carbon nanotubes modified with dual hydroxy functional ionic liquid for the solid-phase extraction of protein.

    Science.gov (United States)

    Chen, Jing; Wang, Yuzhi; Huang, Yanhua; Xu, Kaijia; Li, Na; Wen, Qian; Zhou, Yigang

    2015-05-21

    A novel adsorbent based on silica-coated magnetic multiwall carbon nanotubes (MWCNTs) surface modified by dual hydroxy functional ionic liquid (FIL) ([OH]-FIL-m-MWCNTs@SiO2) has been designed and used for the purification of lysozyme (Lys) by magnetic solid-phase extraction (MSPE). Fourier transform infrared spectroscopy (FTIR), a vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were employed to characterize [OH]-FIL-m-MWCNTs@SiO2. After extraction, the concentration of Lys was determined by a UV-Vis spectrophotometer at 278 nm. A series of single-factor experiments were carried out to identify the optimal conditions of the extraction and the extraction amount could reach up to 94.6 mg g(-1). The RSD of the precision, the repeatability and the stability experiments were 0.37% (n = 3), 0.47% (n = 3) and 0.52% (n = 3), respectively. Comparison of [OH]-FIL-m-MWCNTs@SiO2 with silica-coated magnetic Fe3O4 (Fe3O4@SiO2), silica-coated magnetic multiwall carbon nanotubes (m-MWCNTs@SiO2) and alkyl quaternary ammonium ionic liquid-modified on m-MWCNTs@SiO2 was carried out by extracting Lys. The extraction of bovine serum albumin (BSA), trypsin (Try) and ovalbumin (OVA) was also done by the proposed method. Desorption of Lys was carried out by 0.005 mol L(-1) Na2HPO4-1 mol L(-1) NaCl as the eluent solution and the desorption ratio reached 91.6%. Nearly 97.8% of the [OH]-FIL-m-MWCNTs@SiO2 could be recovered from each run, and the extraction amount decreased less after five runs. The circular dichroism spectral experiment analysis indicated that the secondary structure of Lys was unchanged after extraction.

  20. Electrochemical detection of E. coli O157:H7 using porous pseudo-carbon paste electrode modified with carboxylic multi-walled carbon nanotubes, glutaraldehyde and 3-aminopropyltriethoxysilane.

    Science.gov (United States)

    Xu, Lijian; Du, Jingjing; Deng, Yan; He, Nongyue

    2012-12-01

    Fabrication of three different electrodes based on functional porous pseudo-carbon paste electrodes (PPCPEs) was described. PPCPEs were modified with carboxylic multi-walled carbon nanotubes (PPCPE-COOH), glutaraldehyde (PPCPE-CHO) and 3-aminopropyltriethoxysilane (PPCPE-NH2). The modified electrodes were applied in detection of E. coli O157:H7, it was showed that the electrochemical signal of PPCPE-CHO was the strongest among those three kinds of electrodes. A linear relationship between the anodic stripping peak current and the concentration of E. coli O157:H7 from 1.0 x 10(3) to 1.0 x 10(7) cells/mL and a limit of detection as low as 8.0 x 10(2) cells/mL were obtained when PPCPE-CHO was used.

  1. Inkjet Printing of Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ryan P. Tortorich

    2013-07-01

    Full Text Available In an attempt to give a brief introduction to carbon nanotube inkjet printing, this review paper discusses the issues that come along with preparing and printing carbon nanotube ink. Carbon nanotube inkjet printing is relatively new, but it has great potential for broad applications in flexible and printable electronics, transparent electrodes, electronic sensors, and so on due to its low cost and the extraordinary properties of carbon nanotubes. In addition to the formulation of carbon nanotube ink and its printing technologies, recent progress and achievements of carbon nanotube inkjet printing are reviewed in detail with brief discussion on the future outlook of the technology.

  2. Preparation of glass carbon electrode modified with nanocrystalline nickel-decorated carbon nanotubes and electrocatalytic oxidation of methanol in alkaline solution

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nanocrystalline nickel with an average diameter of about 16 nm and a face-centered cubic (fcc)structure was uniformly attached to the surface of carbon nanotubes (CNT) by wet chemistry.The sample was characterized by X-ray powder diffraction and transmission electron microscopy (TEM).A glass carbon electrode modified with nickel-modified multi-wall carbon nanotubes (MWCNTs-Ni/GCE) was prepared.The electrochemical behavior of the MWCNTs-Ni/GCE and the electrocatalytic oxidation of methanol at the MWCNTsNi/GCE were investigated by cyclic voltammetry in 1.0 mol/L NaOH solution.The cyclic voltammograms showed that the electron transfer between β-Ni(OH)2 and β-NiOOH is mainly a diffusion-controlled quasireversible process,and that the electrode has high catalytic activity for the electrooxidation of methanol in alkaline medium,revealing its potential application in alkaline rechargeable batteries and fuel cells.

  3. Characterization and Hydrogen Storage of Surface-Modified Multiwalled Carbon Nanotubes for Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin

    2012-01-01

    Full Text Available The synthesis, identification, and H2 storage of multiwalled carbon nanotubes (MWCNTs have been investigated in the present work. MWCNTs were produced from the catalytic-assembly solvent (benzene-thermal (solvothermal route. Reduction of C6Cl6 with metallic potassium was carried out in the presence of Co/Ni catalyst precursors at 503–623 K for 12 h. XRD patterns indicated that the abstraction of Cl from hexachlorobenzene and the formation of KCl precipitates were involved in the early stage of the synthesis process of MWCNTs. This result offers further explanation for the formation of MWCNT structure and yield using the solvothermal route depending on the Co/Ni catalyst precursors. The diameter of MWCNTs ranged between 30 and 100 nm and the H2 storage capacity of MWCNTs improved when 2.7–3.8 wt% Pd or NaAlH4 were doped. The XANES/EXAFS spectra revealed that the Co/Ni catalyst precursors of the MWCNT synthesis were in metallic form and Pd atoms possessed a Pd–Pd bond distance of 2.78 Å with a coordination number of 9.08. Ti-NaAlH4 or Pd nanoparticles were dispersed on MWCNTs and facilitated to improve the H2 storage capacity significantly with the surface modification process.

  4. Physisorption of DNA molecules on chemically modified single-walled carbon nanotubes with and without sonication.

    Science.gov (United States)

    Umemura, Kazuo; Ishibashi, Yu; Oura, Shusuke

    2016-09-01

    We investigated the physisorption phenomenon of single-stranded DNA (ssDNA) molecules onto two types of commercially available chemically functionalized single-walled carbon nanotubes (SWNTs) by atomic force microscopy (AFM) and agarose gel electrophoresis. We found that DNA molecules can adsorb on the water-soluble SWNT surfaces without sonication, although sonication treatment has been used for hybridization of DNA and SWNTs in many previous studies. Using our method, damage of DNA molecules by sonication can be avoided. On the other hand, the amount of DNA molecules adsorbed on SWNT surfaces increased when the samples were sonicated. This fact suggests that the sonication is effective not only at debundling of SWNTs, but also at assisting DNA adsorption. Furthermore, DNA adsorption was affected by the types of functionalized SWNTs. In the case of SWNTs functionalized with polyethylene glycol (PEG-SWNT), physisorption of ssDNA molecules was confirmed only by agarose-gel electrophoresis. In contrast, amino-terminated SWNTs (NH2-SWNTs) showed a change in the height distribution profile based on AFM observations. These results suggest that DNA molecules tended to adsorb to NH2-SWNT surfaces, although DNA molecules can also adsorb on PEG-SWNT surfaces. Our results revealed fundamental information for developing nanobiodevices using hybrids of DNA and SWNTs.

  5. Preparation and properties of natural rubber reinforced with polydopamine-coating modified carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Y-L. Lu

    2017-01-01

    Full Text Available Multi-walled carbon nanotubes (MWCNTs were functionalized by polydopamine (PDA-coating and mixed with natural rubber (NR via latex compounding. Compared with pristine MWCNTs, the surface of MWCNT-PDA was covered by an amorphous and nanometer-scale PDA layer which had a large amount of oxygenic and nitric functional groups. So the MWCNT-PDA showed a perfect dispersion in NR matrix. The tensile strength of NR/MWCNT-PDA (5 phr composites is 28.6 MPa, compared with the pure NR, which increased by 42%. For the electrical properties, when the content of MWCNTPDA or MWCNTs is 2 phr, the volume resistivity of NR/MWCNT-PDA composites falls to about 2.7·109 Ω·cm, compared with 3.3·1013 Ω·cm of NR/MWCNT composites. The thermal conductivity of NR composites increased only by 28.2% when 5 phr MWCNT-PDA was added. A model proposed by Nan was used to calculate the thermal conductivity of NR/MWCNT composites, and the calculated values were compared with the experimental values, the results showed that the interface thermal resistance is the main reason why MWCNTs could not significantly increase the thermal conductivity of natural rubber.

  6. Direct Assembly of Modified Proteins on Carbon Nanotubes in an Aqueous Solution

    Science.gov (United States)

    Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol; Harrison, Joycelyn S.

    2007-01-01

    Carbon nanotubes (CNTs) have superior mechanical and electrical properties that have opened up many potential applications. However, poor dispersibility and solubility, due to the substantial van der Waals attraction between tubes, have prevented the use of CNTs in practical applications, especially biotechnology applications. Effective dispersion of CNTs into small bundles or individual tubes in solvents is crucial to ensure homogeneous properties and enable practical applications. In addition to dispersion of CNTs into a solvent, the selection of appropriate solvent, which is compatible with a desired matrix, is an important factor to improve the mechanical, thermal, optical, and electrical properties of CNT-based fibers and composites. In particular, dispersion of CNTs into an aqueous system has been a challenge due to the hydrophobic nature of CNTs. Here we show an effective method for dispersion of both single wall CNTs (SWCNTs) and few wall CNTs (FWCNTs) in an aqueous buffer solution. We also show an assembly of cationized Pt-cored ferritins on the well dispersed CNTs in an aqueous buffer solution.

  7. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    Science.gov (United States)

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood.

  8. Amperometric bienzyme glucose biosensor based on carbon nanotube modified electrode with electropolymerized poly(toluidine blue O) film

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wenju [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Wang Fang [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong)] [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Yao Yanli [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Hu Shengshui [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Shiu, Kwok-Keung, E-mail: kkshiu@hkbu.edu.h [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2010-09-30

    The amperometric bienzyme glucose biosensor utilizing horseradish peroxidase (HRP) and glucose oxidase (GOx) immobilized in poly(toluidine blue O) (PTBO) film was constructed on multi-walled carbon nanotube (MWNT) modified glassy carbon electrode. The HRP layer could be used to analyze hydrogen peroxide with toluidine blue O (TBO) mediators, while the bienzyme system (HRP + GOx) could be utilized for glucose determination. Glucose underwent biocatalytic oxidation by GOx in the presence of oxygen to yield H{sub 2}O{sub 2} which was further reduced by HRP at the MWNT-modified electrode with TBO mediators. In the absence of oxygen, glucose oxidation proceeded with electron transfer between GOx and the electrode mediated by TBO moieties without H{sub 2}O{sub 2} production. The bienzyme electrode offered high sensitivity for amperometric determination of glucose at low potential, displaying Michaelis-Menten kinetics. The bienzyme glucose biosensor displayed linear response from 0.1 to 1.2 mM with a sensitivity of 113 mA M{sup -1} cm{sup -2} at an applied potential of -0.10 V in air-saturated electrolytes.

  9. Detection of Carbofuran with Immobilized Acetylcholinesterase Based on Carbon Nanotubes-Chitosan Modified Electrode

    Directory of Open Access Journals (Sweden)

    Shuping Zhang

    2013-01-01

    Full Text Available A sensitive and stable enzyme biosensor based on efficient immobilization of acetylcholinesterase (AChE to MWNTs-modified glassy carbon electrode (GCE with chitosan (CS by layer-by-layer (LBL technique for rapid determination of carbofuran has been devised. According to the inhibitory effect of carbamate pesticide on the enzymatic activity of AChE, we use carbofuran as a model pesticide. The inhibitory effect of carbofuran on the biosensor was proportional to concentration of carbofuran in the range from  g/L to  g/L with a detection limit of  g/L. This biosensor is a promising new method for pesticide analysis.

  10. New Modified-Multiwall Carbon Nanotubes Paste Electrode for Electrocatalytic Oxidation and Determination of Hydrazine Using Square Wave Voltammetry

    Institute of Scientific and Technical Information of China (English)

    Ali A. ENSAF; Mahsa LOTFI; Hassan KARIMI-MALEH

    2012-01-01

    The application of p-aminophenol as a suitable mediator, as a sensitive and selective voltammetric sensor for the determination of hydrazine using square wave voltammetric method were described. The modified multiwall carbon nanotubes paste electrode exhibited a good electrocatalytic activity for the oxidation of hydrazine at pH = 7.0. The catalytic oxidation peak currents showed a linear dependence of the peaks current to the hydrazine concentrations in the range of 0.5–175 μmol/L with a correlation coefficient of 0.9975. The detection limit (S/N = 3) was estimated to be 0.3 μmol/L of hydrazine. The relative standard deviations for 0.7 and 5.0 μmol/L hydrazine were 1.7 and 1.1%, respectively. The modified electrode showed good sensitivity and selectivity. The diffusion coefficient (D = 9.5 × 10–4 cm2/s) and the kinetic parameters such as the electron transfer coefficient (α = 0.7) of hydrazine at the surface of the modified electrode were determined using electrochemical approaches. The electrode was successfully applied for the determination of hydrazine in real samples with satisfactory results.

  11. Electrocatalytic oxidation and determination of insulin at nickel oxide nanoparticles-multiwalled carbon nanotube modified screen printed electrode.

    Science.gov (United States)

    Rafiee, Banafsheh; Fakhari, Ali Reza

    2013-08-15

    Nickel oxide nanoparticles modified nafion-multiwalled carbon nanotubes screen printed electrode (NiONPs/Nafion-MWCNTs/SPE) were prepared using pulsed electrodeposition of NiONPs on the MWCNTs/SPE surface. The size, distribution and structure of the NiONPs/Nafion-MWCNTs were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD) and also the results show that NiO nanoparticles were homogeneously electrodeposited on the surfaces of MWCNTs. Also, the electrochemical behavior of NiONPs/Nafion-MWCNTs composites in aqueous alkaline solutions of insulin was studied by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS). It was found that the prepared nanoparticles have excellent electrocatalytic activity towards insulin oxidation due to special properties of NiO nanoparticles. Cyclic voltammetric studies showed that the NiONPs/Nafion-MWCNTs film modified SPE, lowers the overpotentials and improves electrochemical behavior of insulin oxidation, as compared to the bare SPE. Amperometry was also used to evaluate the analytical performance of modified electrode in the quantitation of insulin. Excellent analytical features, including high sensitivity (1.83 μA/μM), low detection limit (6.1 nM) and satisfactory dynamic range (20.0-260.0 nM), were achieved under optimized conditions. Moreover, these sensors show good repeatability and a high stability after a while or successive potential cycling.

  12. Fabrication of multiwalled carbon nanotubes/polyaniline modified Au electrode for ascorbic acid determination.

    Science.gov (United States)

    Chauhan, Nidhi; Narang, Jagriti; Pundir, C S

    2011-05-07

    An ascorbate oxidase (AsOx) (E.C.1.10.3.3) purified from Lagenaria siceraria fruit was immobilized covalently onto a carboxylated multiwalled carbon nanotubes and polyaniline (c-MWCNT/PANI) layer electrochemically deposited on the surface of an Au electrode. The diffusion coefficient of ascorbic acid was determined as 3.05 × 10(-4) cm(2) s(-1). The behavior of different electrolytes on electro-deposition was also studied. An ascorbate biosensor was fabricated using a AsOx/c-MWCNT/PANI/Au electrode as a working electrode, Ag/AgCl (3 M/saturated KCl) as standard and Pt wire as an auxiliary electrode connected through a potentiostat. Linear range, response time and detection limit were 2-206 μM, 2 s and 0.9 μM respectively. The biosensor showed optimum response at pH 5.8 and in a broader temperature range (30-45 °C), when polarized at +0.6 V. The biosensor was employed for determination of ascorbic acid level in sera, fruit juices and vitamin C tablets. The sensor was evaluated with 91% recovery of added ascorbic acid in sera and 6.5% and 11.4% within and between batch coefficients of variation respectively for five serum samples. There was a good correlation (r = 0.98) between fruit juice ascorbic acid values by the standard 2,6-dichlorophenolindophenol (DCPIP) method and the present method. The enzyme electrode was used 200 times over a period of two months, when stored at 4 °C. The biosensor has advantages over earlier enzyme sensors in that it has no leakage of enzyme, due to the covalent coupling of enzyme with the support, lower response time, wider working range, higher storage stability and no interference by serum substances.

  13. A hydrogen peroxide sensor based on a horseradish peroxidase/polyaniline/carboxy-functionalized multiwalled carbon nanotube modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Chen, Hsiao-Chien; Liu, Yin-Chih [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-10-30

    We have developed a polyaniline/carboxy-functionalized multiwalled carbon nanotube (PAn/MWCNTCOOH) nanocomposite by blending the emeraldine base form of polyaniline (PAn) and carboxy-functionalized multiwalled carbon nanotubes (MWCNT) in dried dimethyl sulfoxide (DMSO) at room temperature. The conductivity of the resulting PAn/MWCNTCOOH was 3.6 x 10{sup -3} S cm{sup -1}, mainly as a result of the protonation of the PAn with the carboxyl group and the radical cations of the MWCNT fragments. Horseradish peroxidase (HRP) was immobilized within the PAn/MWCNTCOOH nanocomposite modified Au (PAn/MWCNTCOOH/Au) electrode to form HRP/PAn/MWCNTCOOH/Au for use as a hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The adsorption between the negatively charged PAn/MWCNTCOOH nanocomposite and the positively charged HRP resulted in a very good sensitivity to H{sub 2}O{sub 2} and an increased electrochemically catalytical current during cyclic voltammetry. The HRP/PAn/MWCNTCOOH/Au electrode exhibited a broad linear response range for H{sub 2}O{sub 2} concentrations (86 {mu}M-10 mM). This sensor exhibited good sensitivity (194.9 {mu}A mM{sup -1} cm{sup -2}), a fast response time (2.9 s), and good reproducibility and stability at an applied potential of -0.35 V. The construction of the enzymatic sensor demonstrated the potential application of PAn/MWCNTCOOH nanocomposites for the detection of H{sub 2}O{sub 2} with high performance and excellent stability.

  14. Determination of Lead Ion by a Modified Carbon Paste Electrode Based on Multi-Walled Carbon Nanotubes (MWCNTs and Ligand (N-(4-Hydroxyphenyl Ethanamide

    Directory of Open Access Journals (Sweden)

    Marzieh Bagheri

    2015-06-01

    Full Text Available The preparation of a new modified carbon paste electrode (CPE to measure lead ion has been reported in this study. Lead is a highly toxic element which can have a negative impact on the environment. Therefore, measurement of lead in aquatic environments is very important. Although several methods have been developed for determination of lead ion in aquatic environments, there is no a cheap, simple, accurate and rapid method to measure this ion. Aim of this study is to develop a new method to measure the lead based on using multi walls carbon nanotubes (MWCNTs and Paracetamol as an ionophore for modification of a CPE. The optimum composition of modified CPE was determined as 64% of graphite powder, 20% of paraffin oil, 12% of nanotube and 4% of ionophore. This optimum composition was shown high selectivity, with appropriate Nernestian slope (-29.73 mV/decade, linear range (from 1.0×10-1to 1.0×10-8M, low lead concentration detection limit (7.5×10-9M and good response time (equal of 25 sec.The results of this study to introduce a cheap, accurate and simple method for determination of lead ion in aquatic environments.

  15. Determination of Lead Ion by a Modified Carbon Paste Electrode Based on Multi-Walled Carbon Nanotubes (MWCNTs andLigand (N-(4-Hydroxyphenyl Ethanamide

    Directory of Open Access Journals (Sweden)

    Marzieh Bagheri

    2015-06-01

    Full Text Available The preparation of a new modified carbon paste electrode (CPEto measure lead ion has been reported in this study. Lead is a highly toxic element which can have a negative impact on the environment. Therefore, measurement of lead in aquatic environments is very important. Although several methods have been developed for determination of lead ion in aquatic environments, there is no a cheap, simple, accurate and rapid method to measure this ion. Aim of this study is to develop a new method to measure the lead based on using multi walls carbon nanotubes (MWCNTs and Paracetamol as an ionophore for modificationof a CPE.The optimum composition of modified CPE was determined as 64% of graphite powder, 20% of paraffin oil, 12% of nanotube and 4% of ionophore.This optimum composition was shown high selectivity, with appropriate Nernestian slope (-29.73 mV/decade, linear range (from 1.0×10-1to 1.0×10-8M, low lead concentration detection limit (7.5×10-9M and good response time (equal of 25 sec.The results of this study to introduce a cheap, accurate and simple method for determination of lead ion in aquatic environments.

  16. Analytical applications of glassy carbon electrodes modified with multi-wall carbon nanotubes dispersed in polyethylenimine as detectors in flow systems.

    Science.gov (United States)

    Sánchez Arribas, Alberto; Bermejo, Esperanza; Chicharro, Manuel; Zapardiel, Antonio; Luque, Guillermina L; Ferreyra, Nancy F; Rivas, Gustavo A

    2007-07-23

    This work reports the advantages of using glassy carbon electrodes (GCEs) modified with multi-wall carbon nanotubes (CNT) dispersed in polyethylenimine (PEI) as detectors in flow injection and capillary electrophoresis. The presence of the dispersion of CNT in PEI at the electrode surface allows the highly sensitive and reproducible determination of hydrogen peroxide, different neurotransmitters (dopamine (D) and its metabolite dopac, epinephrine (E), norepinephrine (NE)), phenolic compounds (phenol (P), 3-chlorophenol (3-CP) and 2,3-dichlorophenol (2,3CP)) and herbicides (amitrol). Sensitivities enhancements of 150 and 140 folds compared to GCE were observed for hydrogen peroxide and amitrol, respectively. One of the most remarkable properties of the resulting electrode is the antifouling effect of the CNT/PEI layer. No passivation was observed either for successive additions (30) or continuous flow (for 30 min) of the compounds under investigation, even dopac or phenol. A critical comparison of the amperometric and voltammetric signal of these different analytes at bare- and PEI-modified glassy carbon electrodes and pyrolytic graphite electrodes is also included, demonstrating that the superior performance of CNT is mainly due to their unique electrochemical properties. Glassy carbon electrodes modified with CNT-PEI dispersion also show an excellent performance as amperometric detector in the electrophoretic separation of phenolic compounds and neurotransmitters making possible highly sensitive and reproducible determinations.

  17. Templated Growth of Carbon Nanotubes

    Science.gov (United States)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  18. A novel non-enzymatic hydrogen peroxide sensor based on single walled carbon nanotubes-manganese complex modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Abdollah, E-mail: absalimi@uok.ac.i [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Mahdioun, Monierosadat; Noorbakhsh, Abdollah [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Abdolmaleki, Amir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156/83111 (Iran, Islamic Republic of); Ghavami, Raoof [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2011-03-30

    A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single wall carbon nanotubes (SWCNTs) and phenazine derivative of Mn-complex. With immersing the GC/CNTs modified electrode into Mn-complex solution for a short period of time 20-100 s, a stable thin layer of the complex was immobilized onto electrode surface. Modified electrode showed a well defined redox couples at wide pH range (1-12). The surface coverages and heterogeneous electron transfer rate constants (k{sub s}) of immobilized Mn-complex were approximately 1.58 x 10{sup -10} mole cm{sup -2} and 48.84 s{sup -1}. The modified electrode showed excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Detection limit, sensitivity, linear concentration range and k{sub cat} for H{sub 2}O{sub 2} were, 0.2 {mu}M and 692 nA {mu}M{sup -1} cm{sup -2}, 1 {mu}M to 1.5 mM and 7.96({+-}0.2) x 10{sup 3} M{sup -1} s{sup -1}, respectively. Compared to other modified electrodes, this electrode has many advantageous such as remarkable catalytic activity, good reproducibility, simple preparation procedure and long term stability.

  19. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconduct

  20. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa.

    Science.gov (United States)

    Shoja, Yalda; Rafati, Amir Abbas; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH=7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol-gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more--NH2 reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N=3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility.

  1. Role of iron oxide impurities in electrocatalysis by multiwall carbon nanotubes: An investigation using a novel magnetically modified ITO electrodes

    Indian Academy of Sciences (India)

    Kanchan M Samant; Vrushali S Joshi; Kashinath R Patil; Santosh K Haram

    2014-04-01

    The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide (ITO) electrodes, without any chemical binders. The electro-catalytic oxidation of dopamine, and reduction of hydrogen peroxide have been studied by cyclic voltammetry on magnetically modified electrodes with (i) MWCNTs with occluded iron oxide impurities (Fe-MWCNTs), (ii) MWCNTs grown on iron oxide nanoparticle particulate films (Io-MWCNTs) and (iii) pristine iron oxide nanoparticle particulate film (Io-NPs). A shift towards less positive potentials for the oxidation of dopamine was observed which is in the order of Fe-MWCNTs < Io-MWCNTs < Io-NPs. Similarly, trend towards less negative potentials for the reduction of hydrogen peroxide was observed. Thus, the electrocatalytic activities displayed by MWCNTs have been attributed to the iron oxide impurities associated with it. The systematic variation was related to the nature of interaction of iron oxide nanoparticles with MWCNT surface.

  2. Gold Nanoparticle-based Layer-by-Layer Enhancement of DNA Hybridization Electrochemical Signal at Carbon Nanotube Modified Carbon Paste Electrode

    Institute of Scientific and Technical Information of China (English)

    Li Bo NIE; Jian Rong CHEN; Yu Qing MIAO; Nong Yue HE

    2006-01-01

    Colloid gold nanoparticle-based layer-by-layer amplification approach was applied to enhance the electrochemical detection sensitivity of DNA hybridization at carbon nanotube modified carbon paste electrodes (CNTPEs). Streptavidin was immobilized onto the surface of CNTPEs, and the conjugation of biotin labeled target oligonucleotides to the above immobilized streptavidin was performed, followed by the hybridization of target oligonucleotides with the gold nanoparticle-labeled DNA probe and then the layer-by-layer enhanced connection of gold nanoparticles, on which oligonucleotides complementary to the DNA probe were attached, to the hybridization system. The differential pulse voltammetry (DPV) signal of total gold nanoparticles was monitored. It was found that the layer-by-layer colloidal gold DPV detection enhanced the sensitivity by about one order of magnitude compared with that of one-layer detection. One-base mismatched DNA and complementary DNA could be distinguished clearly.

  3. A Novel Electrochemical Sensor for Probing Doxepin Created on a Glassy Carbon Electrode Modified with Poly(4-Amino- benzoic Acid/Multi-Walled Carbon Nanotubes Composite Film

    Directory of Open Access Journals (Sweden)

    Ji-Lie Kong

    2010-09-01

    Full Text Available A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid/multi-walled carbon nanotubes composite film [poly(4-ABA/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 ´ 10−9 to 1.0 ´ 10−6 M, and the detection limit obtained was 1.0 × 10−10 M. The poly(4-ABA/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay.

  4. Carbon nanotubes for supercapacitor.

    Science.gov (United States)

    Pan, Hui; Li, Jianyi; Feng, Yuanping

    2010-01-05

    As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  5. Carbon Nanotubes for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Li Jianyi

    2010-01-01

    Full Text Available Abstract As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  6. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Science.gov (United States)

    Hu, Jie; Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong; Lian, Kun

    2017-02-01

    In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM-1 cm-2 in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  7. Application of a Cu-chitosan/multiwalled carbon nanotube film-modified electrode for the sensitive determination of rutin.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila; Hosseinkhani, Hossein

    2016-01-15

    A new sensitive electrochemical sensor, a glassy carbon electrode modified with chemically cross-linked copper-complexed chitosan/multiwalled carbon nanotubes (Cu-CS/MWCNT/GCE), for rutin analysis was constructed. Experimental investigations of the influence of several parameters showed that the rutin can effectively accumulate on the surface of the Cu-CS/MWCNT/GCE, which accumulation caused a pair of well-defined redox peaks in the electrochemical signal when measurements were carried out in Britton-Robinson buffer solution (pH 3, 0.04 M). The surface of the Cu-CS/MWCNT/GCE was characterized by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry analysis. In a rutin concentration range of 0.05-100 μM and under optimized conditions, a linear relationship between the oxidation peak current of rutin and its concentration was obtained with a detection limit of 0.01 μM. The Cu-CS/MWCNT/GCE showed good selectivity, stability, and reproducibility. Moreover, the sensor was used to determine the presence of rutin in fruits with satisfactory results.

  8. Electrochemical performance of carbon nanotube-modified LiFePO_4 cathodes for Li-ion batteries

    Institute of Scientific and Technical Information of China (English)

    陈召勇; 朱华丽; 朱伟; 张建利; 李奇峰

    2010-01-01

    Carbon nanotubes (CNTs) and acetylene black (AB) were dispersed synchronously or separately between LiFePO4 (LFP) particles as conducting agents during the course of manufacture of LiFePO4 cathodes. The morphology and electrochemical performances of as-prepared LiFePO4 were evaluated by means of transmission electron microscopy (TEM), charge-discharge test, electrochemical impedance spectroscope (EIS) and cyclic voltammetry (CV). CNTs contribute to the interconnection of the isolated LiFePO4 or carbon particles. For the CNTs-modified LiFePO4, it exhibits excellent performance in terms of both specific capacity and cycle life. The initial discharge capacity is 147.9 mA·h/g at 0.2C rate and 134.2 mA·h/g at 1C rate, keeping a capacity retention ratio of 97% after 50 cycles. The results from EIS indicate that the impedance value of the solid electrolyte interface decreases. The cyclic voltammetric peak profiles is more symmetric and spiculate and there are fewer peaks. CNTs are promising conductive additives candidate for high-power Li-ion batteries.

  9. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa

    Energy Technology Data Exchange (ETDEWEB)

    Shoja, Yalda; Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH = 7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol–gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more −NH{sub 2} reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N = 3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility. - Highlights: • Glassy carbon electrode modified by a novel composite in which pPDA as nucleophile is chemically attached to MWCNTs. • The developed biosensor exhibited excellent electrocatalytic activity in electrochemically determination of L-Dopa. • The biosensor showed acceptable sensitivity, reproducibility, detection limit, selectivity and stability. • MWCNT-pPDA provides a good electrical conductivity and large effective surface area for enzyme immobilization.

  10. A simple and sensitive method for the determination of 4-n-octylphenol based on multi-walled carbon nanotubes modified glassy carbon electrode

    Institute of Scientific and Technical Information of China (English)

    Qiaoli Zheng; Ping Yang; He Xu; Jianshe Liu; Litong Jin

    2012-01-01

    A simple and sensitive electroanalytical method was presented for the determination of 4-n-octylphenol (OP) based on multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE).OP was directly oxidized on the MWCNTs/GCE,and the electrochemical oxidation mechanism was demonstrated by a one-electron and one-proton process in the reaction.The oxidation peak current of OP was significantly enhanced by the use of MWCNTs/GCE compared with those of bare glassy carbon electrode; suggesting that the modified electrode can remarkably improve the performance for OP determination.Factors influencing the detection processes were optimized.Under these optimal conditions,a linear relationship between concentration of OP and current response was obtained in the range of 5 × 10-8 to 1 × 10-5 mol/L with a detection limit of 1.5 × 10-8 mol/L and correlation coeffìcient 0.9986.The modified electrode showed good selectivity,sensitivity,reproducibility and high stability.

  11. Cost-effective flow injection amperometric system with metal nanoparticle loaded carbon nanotube modified screen printed carbon electrode for sensitive determination of hydrogen peroxide.

    Science.gov (United States)

    Reanpang, Preeyaporn; Themsirimongkon, Suwaphid; Saipanya, Surin; Chailapakul, Orawon; Jakmunee, Jaroon

    2015-11-01

    Various metal nanoparticles (NPs) decorated on carbon nanotube (CNT) was modified on the home-made screen printed carbon electrode (SPCE) in order to enhances sensitivity of hydrogen peroxide (H2O2) determination. The simple casting method was used for the electrode modification. The monometallic and bimetallic NPs modified electrodes were investigated for their electrochemical properties for H2O2 reduction. The Pd-CNT/SPCE is appropriated to measure the H2O2 reduction at a potential of -0.3 V, then this modified electrode was incorporated with a home-made flow through cell and applied in a simple flow injection amperometry (FI-Amp). Some parameters influencing the resulted modified electrode and the FI-Amp system were studied. The proposed detection system was able to detect H2O2 in the range of 0.1-1.0 mM, with detection limit of 20 µM. Relative standard deviation for 100 replicated injections of 0.6 mM H2O2 was 2.3%. The reproducibility of 6 electrodes preparing in 3 different lots was 8.2%. It was demonstrated for determination of H2O2 in disinfectant, hair colorant and milk samples. Recoveries in the range of 90-109% were observed. The developed system provided high stability, good repeatability, high sample throughput and low reagent consumption.

  12. Voltammetric behavior of dopamine at a glassy carbon electrode modified with NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes.

    Science.gov (United States)

    Ensafi, Ali A; Arashpour, B; Rezaei, B; Allafchian, Ali R

    2014-06-01

    Voltammetric behavior of dopamine was studied on a glassy carbon electrode (GCE) modified-NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes. Impedance spectroscopy and cyclic voltammetry were used to characterize the behavior of dopamine at the surface of modified-GCE. The modified electrode showed a synergic effect toward the oxidation of dopamine. The oxidation peak current is increased linearly with the dopamine concentration (at pH7.0) in wide dynamic ranges of 0.05-6.0 and 6.0-100μmolL(-1) with a detection limit of 0.02μmolL(-1), using differential pulse voltammetry. The selectivity of the method was studied and the results showed that the modified electrode is free from interference of organic compounds especially ascorbic acid, uric acid, cysteine and urea. Its applicability in the determination of dopamine in pharmaceutical, urine samples and human blood serum was also evaluated. The proposed electrochemical sensor has appropriate properties such as high selectivity, low detection limit and wide linear dynamic range when compared with that of the previous reported papers for dopamine detection.

  13. A multi-walled carbon nanotube-modified glassy carbon electrode as a new sensor for the sensitive simultaneous determination of paracetamol and tramadol in pharmaceutical preparations and biological fluids

    OpenAIRE

    Babaei, Ali; Taheri,Ali Reza; Afrasiabi,Mohammad

    2011-01-01

    A chemically modified electrode was constructed based on a multi-walled carbon nanotube-modified glassy carbon electrode (MWCNTs/GCE). It was demonstrated that this sensor can be used for the simultaneous determination of the pharmaceutically important compounds paracetamol (PAR) and tramadol (TRA). The measurements were carried out by the application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. Application of the DPV method demonstrated...

  14. Solid-phase extraction using bis(indolyl)methane-modified silica reinforced with multiwalled carbon nanotubes for the simultaneous determination of flavonoids and aromatic organic acid preservatives.

    Science.gov (United States)

    Wang, Na; Liao, Yuan; Wang, Jiamin; Tang, Sheng; Shao, Shijun

    2015-12-01

    A novel bis(indolyl)methane-modified silica reinforced with multiwalled carbon nanotubes sorbent for solid-phase extraction was designed and synthesized by chemical immobilization of nitro-substituted 3,3'-bis(indolyl)methane on silica modified with multiwalled carbon nanotubes. Coupled with high-performance liquid chromatography analysis, the extraction properties of the sorbent were evaluated for flavonoids and aromatic organic acid compounds. Under optimum conditions, the sorbent can simultaneously extract five flavonoids and two aromatic organic acid preservatives in aqueous solutions in a single-step solid-phase extraction procedure. Wide linear ranges were obtained with correlation coefficients (R(2) ) ranging from 0.9843 to 0.9976, and the limits of detection were in the range of 0.5-5 μg/L for the compounds tested. Compared with the silica modified with multiwalled carbon nanotubes sorbent and the nitro-substituted 3,3'-bis(indolyl)methane-modified silica sorbent, the developed sorbent exhibited higher extraction efficiency toward the selected analytes. The synergistic effect of nitro-substituted 3,3'-bis(indolyl)methane and multiwalled carbon nanotubes not only improved the surface-to-volume ratio but also enhanced multiple intermolecular interactions, such as hydrogen bonds, π-π, and hydrophobic interactions, between the new sorbent and the selected analytes. The as-established solid-phase extraction with high-performance liquid chromatography and diode array detection method was successfully applied to the simultaneous determination of flavonoids and aromatic organic acid preservatives in grape juices with recoveries ranging from 83.9 to 112% for all the selected analytes.

  15. Direct Electrochemistry of Hemoglobin Immobilized on a Functionalized Multi-Walled Carbon Nanotubes and Gold Nanoparticles Nanocomplex-Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Nader Sheibani

    2013-07-01

    Full Text Available Direct electron transfer of hemoglobin (Hb was realized by immobilizing Hb on a carboxyl functionalized multi-walled carbon nanotubes (FMWCNTs and gold nanoparticles (AuNPs nanocomplex-modified glassy carbon electrode. The ultraviolet-visible absorption spectrometry (UV-Vis, transmission electron microscopy (TEM and Fourier transform infrared (FTIR methods were utilized for additional characterization of the AuNPs and FMWCNTs. The cyclic voltammogram of the modified electrode has a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.270 ± 0.002 V (vs. Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks was evaluated to be 4.0 ± 0.2 s−1. The average surface concentration of electro-active Hb on the surface of the modified glassy carbon electrode was calculated to be 6.8 ± 0.3 × 10−10 mol cm−2. The cathodic peak current of the modified electrode increased linearly with increasing concentration of hydrogen peroxide (from 0.05 nM to 1 nM with a detection limit of 0.05 ± 0.01 nM. The apparent Michaelis-Menten constant (Kmapp was calculated to be 0.85 ± 0.1 nM. Thus, the modified electrode could be applied as a third generation biosensor with high sensitivity, long-term stability and low detection limit.

  16. Carbon nanotubes and graphene modified screen-printed carbon electrodes as sensitive sensors for the determination of phytochelatins in plants using liquid chromatography with amperometric detection.

    Science.gov (United States)

    Dago, Àngela; Navarro, Javier; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2015-08-28

    Nanomaterials are of great interest for the development of electrochemical sensors. Multi-walled carbon nanotubes and graphene were used to modify the working electrode surface of different screen-printed carbon electrodes (SPCE) with the aim of improving the sensitivity of the SPCE and comparing it with the conventional glassy carbon electrode. To assay the usability of these sensors, a HPLC methodology with amperometric detection was developed to analyze several phytochelatins in plants of Hordeum vulgare and Glycine max treated with Hg(II) or Cd(II) giving detection limits in the low μmolL(-1) range. Phytochelatins are low molecular weight peptides with the general structure γ-(Glu-Cys)n-Gly (n=2-5) which are synthesized in plants in the presence of heavy metal ions. These compounds can chelate heavy metal ions by the formation of complexes which, are transported to the vacuoles, where the toxicity is not threatening. For this reason phytochelatins are essential in the detoxification of heavy metal ions in plants. The developed HPLC method uses a mobile phase of 1% of formic acid in water with KNO3 or NaCl (pH=2.00) and 1% of formic acid in acetonitrile. Electrochemical detection at different carbon-based electrodes was used. Among the sensors tested, the conventional glassy carbon electrode offers the best sensitivity although modification improves the sensitivity of the SPCE. Glutathione and several isoforms of phytochelatin two were found in plant extracts of both studied species.

  17. Carbon nanotube filters

    Science.gov (United States)

    Srivastava, A.; Srivastava, O. N.; Talapatra, S.; Vajtai, R.; Ajayan, P. M.

    2004-09-01

    Over the past decade of nanotube research, a variety of organized nanotube architectures have been fabricated using chemical vapour deposition. The idea of using nanotube structures in separation technology has been proposed, but building macroscopic structures that have controlled geometric shapes, density and dimensions for specific applications still remains a challenge. Here we report the fabrication of freestanding monolithic uniform macroscopic hollow cylinders having radially aligned carbon nanotube walls, with diameters and lengths up to several centimetres. These cylindrical membranes are used as filters to demonstrate their utility in two important settings: the elimination of multiple components of heavy hydrocarbons from petroleum-a crucial step in post-distillation of crude oil-with a single-step filtering process, and the filtration of bacterial contaminants such as Escherichia coli or the nanometre-sized poliovirus (~25 nm) from water. These macro filters can be cleaned for repeated filtration through ultrasonication and autoclaving. The exceptional thermal and mechanical stability of nanotubes, and the high surface area, ease and cost-effective fabrication of the nanotube membranes may allow them to compete with ceramic- and polymer-based separation membranes used commercially.

  18. Carbon nanotubes for microelectronics?

    Science.gov (United States)

    Graham, Andrew P; Duesberg, Georg S; Seidel, Robert V; Liebau, Maik; Unger, Eugen; Pamler, Werner; Kreupl, Franz; Hoenlein, Wolfgang

    2005-04-01

    Despite all prophecies of its end, silicon-based microelectronics still follows Moore's Law and continues to develop rapidly. However, the inherent physical limits will eventually be reached. Carbon nanotubes offer the potential for further miniaturization as long as it is possible to selectively deposit them with defined properties.

  19. CO2 Removal from Biogas Using Carbon Nanotubes Mixed Matrix Membranes

    Directory of Open Access Journals (Sweden)

    Tutuk Djoko Kusworo

    2010-07-01

    Full Text Available A new type of mixed matrix membrane consisting of polyethersulfone (PES and carbon nanotubes (CNTs is prepared for biogas purification application. PES mixed matrix membrane with and without modification of carbon nanotubes were prepared by a dry/wet phase inversion technique using a pneumatically membrane casting machine system. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using acid treatment to allow PES chains to be grafted on carbon nanotubes surface. The results from the FESEM, DSC and FTIR analysis confirmed that chemical modification on carbon nanotubes surface had taken place. Meanwhile, the nanogaps in the interface of polymer and carbon nanotubes were appeared in the PES mixed matrix membrane with unmodified of carbon nanotubes. The modified carbon nanotubes mixed matrix membrane increases the mechanical properties and the permeability of all gases. For PES-modified carbon nanotubes mixed matrix membrane the maximum selectivity achieved for CO2/CH4 is 23.54

  20. Potentiometric stripping analysis of bismuth based on carbon paste electrode modified with cryptand [2.2.1]and multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Gadhari, Nayan S.; Sanghavi, Bankim J. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India); Karna, Shashi P. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, ATTN: RDRL-WM, Aberdeen Proving Ground, MD 21005-5069 (United States); Srivastava, Ashwini K., E-mail: aksrivastava@chem.mu.ac.i [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India)

    2010-12-30

    An electrochemical method based on potentiometric stripping analysis (PSA) employing a cryptand [2.2.1](CRY) and carbon nanotube (CNT) modified paste electrode (CRY-CNT-PE) has been proposed for the subnanomolar determination of bismuth. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). It was observed that by employing CRY-CNT-PE, a 9-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (s/V) was proportional to the Bi(III) concentration in the range of 5.55 x 10{sup -8} to 9.79 x 10{sup -11} M (r = 0.9990) with the detection limit (S/N = 3) of 3.17 x 10{sup -11} M. The practical analytical utilities of the modified electrode were demonstrated by the determination of bismuth in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the results obtained for bismuth analysis in commercial and real samples using CRY-CNT-PE and those obtained by atomic absorption spectroscopy (AAS) are in agreement at the 95% confidence level.

  1. Determination of Dopamine in the Presence of Ascorbic Acid by Nafion and Single-Walled Carbon Nanotube Film Modified on Carbon Fiber Microelectrode

    Directory of Open Access Journals (Sweden)

    Haesang Jeong

    2008-11-01

    Full Text Available Carbon fiber microelectrode (CFME modified by Nafion and single-walled carbon nanotubes (SWNTs was studied by voltammetric methods in phosphate buffer saline (PBS solution at pH 7.4. The Nafion-SWNTs/CFME modified microelectrode exhibited strongly enhanced voltammetric sensitivity and selectivity towards dopamine (DA determination in the presence of ascorbic acid (AA. Nafion-SWNTs film accelerated the electron transfer reaction of DA, but Nafion film as a negatively charged polymer restrained the electrochemical response of AA. Voltammetric techniques separated the anodic peaks of DA and AA, and the interference from AA was effectively excluded from DA determination. Linear calibration plots were obtained in the DA concentration range of 10 nM - 10 μM and the detection limit of the anodic current was determined to be 5 nM at a signal-to-noise ratio of 3. The study results demonstrate that DA can be determined without any interference from AA at the modified microelectrode, thereby increasing the sensitivity, selectivity, and reproducibility and stability.

  2. Determination of serotonin on a glassy carbon electrode modified by electropolymerization of meso-tetrakis(2-aminophenyl)porphyrin and single walled carbon nanotubes.

    Science.gov (United States)

    Kim, Seul Ki; Ahmed, Mohammad Shamsuddin; Jeong, Haesang; You, Jung-Min; Jeon, Seungwon

    2011-03-01

    A chemically modified electrode [poly(TAPP)-SWNT/GCE] was prepared by electropolymerization of meso-tetrakis(2-aminophenyl)porphyrin (TAPP)-single walled carbon nanotubes (SWNT) on the surface of a glassy carbon electrode (GCE). This modified electrode was employed as an electrochemical biosensor for the determination of serotonin concentration and exhibited a typical enhance effect on the current response of serotonin and lower oxidation overpotential. The biosensor was very effective to determined 5-HT in a mixture. The linear response was in the range 2.0 x 10(-7) to 1.0 x 10(-5) M, with a correlation coefficient of 0.999 [i(p)(microA) = 3.406 C (microM)+0.132] on the anodic current, with a detection limit of 1 x 10(-9) M. Due to the relatively low currents and different potentials in the electrochemical responses to ascorbic acid and dopamine, the modified electrode is a useful and effective sensing device for the selective and sensitive serotonin determination in the presence of ascorbic acid and dopamine.

  3. Methanol Oxidation over TiO2-modified Multi-walled Carbon Nanotubes Supported Pt-Mo Electrocatalyst

    Institute of Scientific and Technical Information of China (English)

    WANG Xiu-yu; JIANG Yuan-sheng; ZHU Hong; ZHANG Jing-chang

    2011-01-01

    In order to develop a novel and high-performance catalytic material for direct methanol fuel cells(DMFC),molybdenum oxide as a co-catalyst with Pt on multi-walled carbon nanotubes which were modified by titanium dioxide(denoted as CNTs@TiO2) was investigated. The physicochemical characterizations of the catalysts were carried out via X-ray diffraction(XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS).Cyclic voltammetry(CV) showed that the CO-tolerance performance increased in the sequence of Pt/CNTs<Pt/CNTs@TiO2<Pt-Mo/CNTs@TiO2. The improved CO-tolerance performance of the Pt-Mo/CNTs@TiO2 catalyst can be attributed to the combined beneficial effects of highly dispersed Pt nanoparticles on the CNTs, the existence of oxygen holes in the MoO3 layer structure and the oxidation capability of TiO2.

  4. Application of β-cyclodextrin-modified, carbon nanotube-reinforced hollow fiber to solid-phase microextraction of plant hormones.

    Science.gov (United States)

    Song, Xin-Yue; Ha, Wei; Chen, Juan; Shi, Yan-Ping

    2014-12-29

    A new, efficient, and environmental friendly solid-phase microextraction (SPME) medium based on β-cyclodextrin (β-CD)-modified carbon nanotubes (CNTs) and a hollow fiber (HF) was prepared. Functionalized β-CD was covalently linked to the surface of the carboxylic CNTs and then the obtained nanocomposite was immobilized into the wall pores of HFs under ultrasonic-assisted effect. The scanning electron microscope was used to inspect surface characteristics of fibers, demonstrating the presence of nanocomposites in their wall pores. The reinforced HF was employed in SPME, and its extraction performance was evaluated by analyzing 1-naphthaleneacetic acid (NAA) and 2-naphthoxyacetic acid (2-NOA) in vegetables. Without any tedious clean-up procedure, analytes were extracted from the sample to the adsorbent and organic solvent immobilized in HFs and then desorbed in acetonitrile prior to chromatographic analysis. Under the optimized extraction conditions, the method provided 275- and 283-fold enrichment factors of NAA and 2-NOA, low limits of detection and quantification (at an ngg(-1) level), satisfactory spiked recoveries, good inter-fiber repeatability, and batch-to-batch reproducibility. The selectivity of the developed fiber was investigated to three structurally similar compounds and two reference compounds with recognition coefficients up to 3.18. The obtained results indicate that the newly developed fiber is a feasible, selective, green, and cost-effective microextraction medium and could be successfully applied for extraction and determination of naphthalene-derived plant hormones in complex matrices.

  5. Selective detection of dopamine in the presence of ascorbic acid using carbon nanotube modified screen-printed electrodes.

    Science.gov (United States)

    Moreno, Mónica; Arribas, Alberto Sánchez; Bermejo, Esperanza; Chicharro, Manuel; Zapardiel, Antonio; Rodríguez, Marcela C; Jalit, Yamile; Rivas, Gustavo A

    2010-03-15

    This work reports on the performance of carbon nanotube modified screen-printed electrodes (SPE-MWCNT) for the selective determination of dopamine (DA) in the presence of ascorbic acid (AA) by adsorptive stripping voltammetry (AdSV). Several operating conditions and parameters were examined including the electrochemical pre-treatment and the previous AA interaction and DA accumulation in the presence AA at physiological conditions. Under the chosen conditions, DA peak current of differential pulse voltammograms increases linearly with DA concentration in the range of 5.0 x 10(-8) to 1.0 x 10(-6) mol L(-1) with a limit of detection of 1.5 x 10(-8) mol L(-1) in connection with 600s accumulation time. The sensitivity obtained for DA was independent from the presence or absence of AA; therefore, the proposed method can be readily applied to detect DA in real samples. The proposed methodology was successfully used for the quantification of DA in urine samples.

  6. Electrochemical Behavior and Determination of Chlorogenic Acid Based on Multi-Walled Carbon Nanotubes Modified Screen-Printed Electrode

    Directory of Open Access Journals (Sweden)

    Xiaoyan Ma

    2016-10-01

    Full Text Available In this paper, the multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs/SPE was prepared and the MWCNTs/SPE was employed for the electrochemical determination of the antioxidant substance chlorogenic acids (CGAs. A pair of well-defined redox peaks of CGA was observed at the MWCNTs/SPE in 0.10 mol/L acetic acid-sodium acetate buffer (pH 6.2 and the electrode process was adsorption-controlled. Cyclic voltammetry (CV and differential pulse voltammetry (DPV methods for the determination of CGA were proposed based on the MWCNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 0.17 to 15.8 µg/mL, and the linear regression equation was Ipa (µA = 4.1993 C (×10−5 mol/L + 1.1039 (r = 0.9976 and the detection limit for CGA could reach 0.12 µg/mL. The recovery of matrine was 94.74%–106.65% (RSD = 2.92% in coffee beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA.

  7. Electrochemical Behavior and Determination of Chlorogenic Acid Based on Multi-Walled Carbon Nanotubes Modified Screen-Printed Electrode

    Science.gov (United States)

    Ma, Xiaoyan; Yang, Hongqiao; Xiong, Huabin; Li, Xiaofen; Gao, Jinting; Gao, Yuntao

    2016-01-01

    In this paper, the multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs/SPE) was prepared and the MWCNTs/SPE was employed for the electrochemical determination of the antioxidant substance chlorogenic acids (CGAs). A pair of well-defined redox peaks of CGA was observed at the MWCNTs/SPE in 0.10 mol/L acetic acid-sodium acetate buffer (pH 6.2) and the electrode process was adsorption-controlled. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods for the determination of CGA were proposed based on the MWCNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 0.17 to 15.8 µg/mL, and the linear regression equation was Ipa (µA) = 4.1993 C (×10−5 mol/L) + 1.1039 (r = 0.9976) and the detection limit for CGA could reach 0.12 µg/mL. The recovery of matrine was 94.74%–106.65% (RSD = 2.92%) in coffee beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA. PMID:27801797

  8. Enhanced dielectric performance of three phase percolative composites based on thermoplastic-ceramic composites and surface modified carbon nanotube

    Science.gov (United States)

    Yang, Yang; Sun, Haoliang; Zhu, Benpeng; Wang, Ziyu; Wei, Jianhong; Xiong, Rui; Shi, Jing; Liu, Zhengyou; Lei, Qingquan

    2015-01-01

    Three-phase composites were prepared by embedding CaCu3Ti4O12(CCTO) nanoparticles and Multiwalled Carbon Nanotube (MWNT) into polyimide (PI) matrix via in-situ polymerization. The dependences of electric and dielectric properties of the resultant composites on volume fractions of filler and frequency were investigated. The dielectric permittivity of PI/CCTO-surface modified MWNT (MWNT-S) composite reached as high as 252 at 100 Hz at 0.1 vol. % filler (MWNT-S), which is about 63 times higher than that of pure PI. Also the dielectric loss is only 0.02 at 100 Hz. The results are in good agreement with the percolation theory. It is shown that embedding high aspect ratio MWNT-S in PI/CCTO composites is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  9. Design of a multiwalled carbon nanotube-Nafion-cysteamine modified tyrosinase biosensor and its adaptation of dopamine determination.

    Science.gov (United States)

    Canbay, Erhan; Akyilmaz, Erol

    2014-01-01

    In this work, a multiwalled carbon nanotube (MWCNT)-Nafion-cysteamine (CA) modified tyrosinase biosensor brings a new and original perspective to biosensor technology intended for the development of dopamine determination. Dopamine measurements were done at 0.2V with the amperometric method by the developed biosensor system. In addition, in this study dopamine determination was carried out by using the differential pulse voltammetry method between potentials of 0.4 and -0.15 V. In the optimization studies of the biosensor, some parameters such as optimal pH, optimal temperature, optimal enzyme amount, and effect of MWCNT concentration were investigated. Afterward, in the characterization studies, some parameters such as linearity and reproducibility were determined. In the reproducibility experiment, an average value of 1.026 μM, a standard deviation of ±0.03975, and a coefficient of variation of 3.8% were determined for a 1-μM dopamine concentration (n=15). Determination of dopamine was carried out in drug samples by the developed biosensor.

  10. Design and Analysis of New Modified Feedthrough Logic (MFTL Circuits Using Carbon Nanotube Field Effect Transistor (CNTFET

    Directory of Open Access Journals (Sweden)

    Sneha Meryn Thomas

    2014-08-01

    Full Text Available It is a challenging task for a VLSI design engineer to develop low power VLSI circuits, without sacrificing its performance. Feedthrough Logic (FTL is a new technology which could be considered better than the existing technologies for improving circuit efficiency. Modified Feedthrough Logic (MFTL, offers a better power factor than the FTL logic structures, and also shows an improvement in the speed factor. But the scenario again changes when the design extends to nano scales of device dimension, where many factors which were neglected otherwise need to be given more importance. To avoid or minimize problems like hot carrier effects, electro migration, drain induced barrier lowering and other issues that becomes prominent in nano scale MOSFET‟s, Carbon Nanotube Field Effect Transistor (CNTFET is considered to be a promising candidate in future integrated circuits. Hence this work extends the advantages of MFTL logic into nano level by incorporating CNTFETs in place of MOSFETs. The modifications have been implemented using CNTFETs of 16nm technology from HSPICE library on a 10 chain inverter stage, an 8 bit RCA and a Vedic multiplier and performance factors like PDP and ADP are compared to that of the conventional MOSFET circuits.

  11. Nitrogen doping in carbon nanotubes.

    Science.gov (United States)

    Ewels, C P; Glerup, M

    2005-09-01

    Nitrogen doping of single and multi-walled carbon nanotubes is of great interest both fundamentally, to explore the effect of dopants on quasi-1D electrical conductors, and for applications such as field emission tips, lithium storage, composites and nanoelectronic devices. We present an extensive review of the current state of the art in nitrogen doping of carbon nanotubes, including synthesis techniques, and comparison with nitrogen doped carbon thin films and azofullerenes. Nitrogen doping significantly alters nanotube morphology, leading to compartmentalised 'bamboo' nanotube structures. We review spectroscopic studies of nitrogen dopants using techniques such as X-ray photoemission spectroscopy, electron energy loss spectroscopy and Raman studies, and associated theoretical models. We discuss the role of nanotube curvature and chirality (notably whether the nanotubes are metallic or semiconducting), and the effect of doping on nanotube surface chemistry. Finally we review the effect of nitrogen on the transport properties of carbon nanotubes, notably its ability to induce negative differential resistance in semiconducting tubes.

  12. Thermo-sensitive liposomes loaded with doxorubicin and lysine modified single-walled carbon nanotubes as tumor-targeting drug delivery system.

    Science.gov (United States)

    Zhu, Xiali; Xie, Yingxia; Zhang, Yingjie; Huang, Heqing; Huang, Shengnan; Hou, Lin; Zhang, Huijuan; Li, Zhi; Shi, Jinjin; Zhang, Zhenzhong

    2014-11-01

    This report focuses on the thermo-sensitive liposomes loaded with doxorubicin and lysine-modified single-walled carbon nanotube drug delivery system, which was designed to enhance the anti-tumor effect and reduce the side effects of doxorubicin. Doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes was prepared by reverse-phase evaporation method, the mean particle size was 232.0 ± 5.6 nm, and drug entrapment efficiency was 86.5 ± 3.7%. The drug release test showed that doxorubicin released more quickly at 42℃ than at 37℃. Compared with free doxorubicin, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes could efficiently cross the cell membranes and afford higher anti-tumor efficacy on the human hepatic carcinoma cell line (SMMC-7721) cells in vitro. For in vivo experiments, the relative tumor volumes of the sarcomaia 180-bearing mice in thermo-sensitive liposomes group and doxorubicin group were significantly smaller than those of N.S. group. Meanwhile, the combination of near-infrared laser irradiation at 808 nm significantly enhanced the tumor growth inhibition both on SMMC-7721 cells and the sarcomaia 180-bearing mice. The quality of life such as body weight, mental state, food and water intake of sarcomaia 180 tumor-bearing mice treated with doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes were much higher than those treated with doxorubicin. In conclusion, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes combined with near-infrared laser irradiation at 808 nm may potentially provide viable clinical strategies for targeting delivery of anti-cancer drugs.

  13. Multi-walled carbon nanotube/poly(glycine) modified carbon paste electrode for the determination of dopamine in biological fluids and pharmaceuticals.

    Science.gov (United States)

    Thomas, Tony; Mascarenhas, Ronald J; Swamy, B E Kumara; Martis, Praveen; Mekhalif, Zineb; Sherigara, B S

    2013-10-01

    A modified carbon paste electrode (CPE) for the selective detection of dopamine (DA) in presence of large excess of ascorbic acid (AA) and uric acid (UA) at physiological pH has been fabricated by bulk modification of CPE with multi-walled carbon nanotubes (MWCNTs) followed by electropolymerization of glycine (Gly). The surface morphology is compared using SEM images. The presence of nitrogen was confirmed by the energy dispersion X-ray spectroscopy (EDS) indicating the polymerization of Gly on the surface of the modified electrode. The impedance study indicates a better charge transfer kinetics for DA at CPE modified with MWCNT/polyglycine electrode. The presence of MWCNTs in carbon paste matrix triggers the extent of electropolymerization of Gly and imparts more selectivity towards DA by electrochemically not sensing AA below a concentration of 3.1×10(-4)M. Due to the exclusion of the signal for AA, the interference of AA in the determination of DA is totally ruled out by DPV method which is used for its detection at lower concentrations. Large peak separation, good sensitivity, reproducibility and stability allow this modified electrode to analyze DA individually and simultaneously along with AA and UA. Detection limit of DA was determined from differential pulse voltammetric (DPV) study and found to be 1.2×10(-8)M with a linear dynamic range of 5.0×10(-7)M to 4.0×10(-5)M. The practical analytical application of this electrode was demonstrated by measurement of DA content in dopamine hydrochloride injection and human blood serum.

  14. The Toxicology of Carbon Nanotubes

    Science.gov (United States)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  15. Adsorption of mercury from water by modified multi-walled carbon nanotubes: adsorption behaviour and interference resistance by coexisting anions.

    Science.gov (United States)

    Chen, Paris Honglay; Hsu, Cheng-Feng; Tsai, David Dah-wei; Lu, Yen-Ming; Huang, Winn-Jung

    2014-08-01

    This investigation reports the use of modified multi-walled carbon nanotubes (MWCNTs) with various functional groups for adsorbing inorganic divalent mercury (Hg(II)) from water samples. To elucidate the behaviours and mechanisms of Hg(II) adsorption by modified MWCNTs, their adsorption capacity was studied by considering adsorption isotherms and kinetics. Particular attention was paid to interference of coexisting inorganic ions with Hg(II) adsorption. The results reveal that functionalization with oxygen-containing groups improved the Hg(II) adsorption capacity of the MWCNTs. Kinetic analysis demonstrated that the adsorption of Hg(II) by MWCNTs was closely described by the pseudo-second-order and Elovich models, suggesting that the adsorption of Hg(II) by MWCNTs was significantly affected by chemical adsorption. The kinetic results were also analysed using the intraparticle diffusion model, which revealed that intraparticle diffusion was not the only rate-controlling mechanism. The adsorption of Hg(II) on MWCNTs fell drastically as the ionic strength increased from 0 to 1.0mol/L chloride ions, and declined significantly as the pH increased from 2.2 to 10.5. The elemental maps obtained by energy-dispersive spectrometer (EDS) revealed the formation of surface complexes of chloride ions with functional groups on MWCNTs, which reduced the number of available sites for the adsorption of Hg(II) and strengthened the repulsive forces between Hg(II) and MWCNTs. The EDS results suggest that chloride ions are important in controlling Hg(II) speciation and adsorption on the surfaces of MWCNTs.

  16. Production of carbon nanotubes

    Science.gov (United States)

    Journet, C.; Bernier, P.

    Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar technique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposition of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

  17. An electrochemical sensor for rizatriptan benzoate determination using Fe3O4 nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples.

    Science.gov (United States)

    Madrakian, Tayyebeh; Maleki, Somayeh; Heidari, Mozhgan; Afkhami, Abbas

    2016-06-01

    In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles (Fe3O4/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe3O4 nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5-100.0 μmol L(-1) with a detection limit of 0.09 μmol L(-1) under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical.

  18. Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid.

    Science.gov (United States)

    Afraz, Ahmadreza; Rafati, Amir Abbas; Najafi, Mojgan

    2014-11-01

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450 μM, respectively, and with 120, 30 and 30 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine.

  19. Application of carbon nanotubes in modified oxidase biosensors%碳纳米管在修饰酶传感器中的应用

    Institute of Scientific and Technical Information of China (English)

    赵文秀; 董宏博; 张伟萍; 崔桂花

    2008-01-01

    碳纳米管是一种新兴的纳米材料,碳纳米管良好的电子传递能力使其可用于修饰电极,可以降低化学物质氧化还原反应的过电位,改善生物分子氧化还原可逆性;其大比表面积有利于酶的固定化,还能促进酶活性中心与电极表面的电子传递;功能化的碳纳米管还能与各种生物分子键合将其固定于电极表面.随着制备和纯化工艺的改进,碳纳米管将为生物传感器的发展开创更广阔的前景.本文总结和分析碳纳米管在生物传感器中的应用、研究现状和发展趋势.综述了吸附型、糊类、原位生长(阵列)型和共价键合型等几种类型碳纳米管修饰酶传感器及在DNA生物传感器中的应用,并对各种传感器的制备、特点和研究现状进行了述评.%Carbon nanotubes are a novel kind of nano-materials, and contribute to modify electrodes using their good capacity of electric transmission. Furthermore, carbon nanotubes may reduce the overpotential caused by the oxidation-reduction reaction of chemical materials, and ameliorate the oxidation-reduction reversibility of the biomolecules; Their wide specific surface area leads to enzyme immobilization and promote the electric transmission between enzyme active center and electrode surface; Functionalized carbon nanotubes bonding with various biomolecules will benefit to fix these biomolecules on the electrode surface. With the development of preparation and purification techniques, carbon nanotubes may widen the prospect of biosensors applied. The aim of this paper is to summarize and analyze the application, research status and development tendency of carbon nanotubes with regard to biosensors. Moreover, this paper reviews various carbon nanotubes modified oxidase biosensors, such as adsorption, paste, array and covalent bond, together with their application on DNA biosensor. The preparation, characteristics and research status of various sensors are also summarized.

  20. Preparation of electrochemically reduced graphene oxide/multi-wall carbon nanotubes hybrid film modified electrode, and its application to amperometric sensing of rutin

    Indian Academy of Sciences (India)

    Uling Yang; Gang Li; Meifang Hu; Lingbo Qu

    2014-07-01

    Through a facile electrochemical method, we prepared an electrochemically reduced graphene oxide (ERGO)/multi-wall carbon nanotubes (MWNTs) hybrid film modified glassy carbon electrode (GCE), and characterized it by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) The experimental results demonstrated that ERGO-MWNTs/GCE exhibited excellent electrocatalytic activity toward rutin as evidenced by the significant enhancement of redox peak currents in comparison with a bare GCE, ERGO/GCE and MWNTs/GCE. This method has been applied for the direct determination of rutin in real samples with satisfactory results.

  1. Carbon nanotube network varactor

    Science.gov (United States)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  2. Carbon Nanotube Thermoelectric Coolers

    Science.gov (United States)

    2015-02-06

    conductance. Inside thecentral section of the carbon nanotube, we obtained an impressive Peltier cooling 57 K down from the liquid nitrogentemperature. 15... trapped charges or dipoles) that occur either at the interface between the CNT and the gate dielectric (interface defects) or at some position within... liquid nitrogen temperature 77T  K up to hot 134 8T  K, or decreases from 77T  K down to about cold 20 6T  K, thus evidencing a strong

  3. Carbon nanotube biosensors

    OpenAIRE

    Tîlmaciu, Carmen-Mihaela; Morris, May C

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we pr...

  4. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  5. From Carbon Nanotube Crystals to Carbon Nanotube Flowers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhengjun; ZHAO Ye; ZHOU Ya

    2005-01-01

    We have investigated the very initial deposition stages of chemical vapor deposition (CVD) with ferrocene (Fe(C5H5)2) and xylene (C8H10) for growing carbon nanotubes, and made clear that the mechanism for the self-organization behaviors of nanotubes at different growth stages by this approach. For instance, the organization of nanotubes into flower-like structures at prolonged deposition is developed from the crystal-like structures formed at early growth stages, both of which are closely related to and determined by the very initial deposition stages of this CVD approach. Based on this approach, ways have been established to build up different architectures of carbon nanotubes, by controlling the initial deposition stages of the CVD process, with which we have realized the selective growth of self-organized carbon nanotube structures. This study provides a new idea for growing carbon nanotube architectures by CVD.

  6. p-toluene sulfonic acid doped polyaniline carbon nanotube composites: synthesis via different routes and modified properties

    OpenAIRE

    Sharma, Ashok K.; YASHPAL SHARMA

    2013-01-01

    Composites of polyaniline and carbon nanotube (CNT) were prepared by in-situ chemical polymerization method using various aniline concentrations in the initial polymerization solution with p-toluene sulfonic acid (PTS) as secondary dopant and mechanical mixing of the PANI and CNT using different weight ratios of PANI and CNTs. The structural characterizations of the composites were done by Fourier transform infrared (FTIR) and Ultra violet visible spectroscopy (UV-Visible). Scanning electron ...

  7. Reinforcing effect of plasma modified halloysite nanotubes in a carbon black filled natural rubber-butadien rubber matrix

    OpenAIRE

    Poikelispaa, Minna; Das, Amit; Dierkes, Wilma; Vuorinen, Jyrki

    2011-01-01

    Rubber composites are generally produced by the direct incorporation of fillers like carbon black and/or silica into the rubber matrix. The incorporation of different types of nanofillers is the subject of recent research with the aim of preparing composites with special compositions and properties. A successful application of such composites depends mainly on the degree of dispersion of the nano-sized fillers. Recently, a naturally occurring clay mineral, halloysite nanotubes (HNTs), is inve...

  8. Carbon Nanotubes Based Quantum Devices

    Science.gov (United States)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  9. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei;

    2014-01-01

    It is crucial to accurately describe the interaction between the surface functionality and the supported metal catalyst because it directly determines the activity and selectivity of a catalytic reaction. It is, however, challenging with a metal-carbon catalytic system owing to the ultrafine feat...

  10. Simultaneous determination of mycophenolate mofetil and its active metabolite, mycophenolic acid, by differential pulse voltammetry using multi-walled carbon nanotubes modified glassy carbon electrode.

    Science.gov (United States)

    Madrakian, Tayyebeh; Soleimani, Mohammad; Afkhami, Abbas

    2014-09-01

    A highly sensitive electrochemical sensor for the simultaneous determination of mycophenolate mofetil (MPM) and mycophenolic acid (MPA) was fabricated by multi-walled carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE). The electrochemical behavior of these two drugs was studied at the modified electrode using cyclic voltammetry and adsorptive differential pulse voltammetry. MPM and MPA were oxidized at the GCE during an irreversible process. DPV analysis showed two oxidation peaks at 0.87V and 1.1V vs. Ag/AgCl for MPM and an oxidation peak at 0.87V vs. Ag/AgCl for MPA in phosphate buffer solution of pH5.0. The MWCNTs/GCE displayed excellent electrochemical activities toward oxidation of MPM and MPA relative to the bare GCE. The experimental design algorithm was used for optimization of DPV parameters. The electrode represents linear responses in the range 5.0×10(-6) to 1.6×10(-4)molL(-1) and 2.5×10(-6)molL(-1) to 6.0×10(-5)molL(-1) for MPM and MPA, respectively. The detection limit was found to be 9.0×10(-7)molL(-1) and 4.0×10(-7)molL(-1) for MPM and MPA, respectively. The modified electrode showed a good sensitivity and stability. It was successfully applied to the simultaneous determination of MPM and MPA in plasma and urine samples.

  11. An amperometric hydrogen peroxide biosensor based on Co{sub 3}O{sub 4} nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kaçar, Ceren; Dalkiran, Berna; Erden, Pınar Esra, E-mail: erdenpe@gmail.com; Kiliç, Esma

    2014-08-30

    Highlights: • Hydrogen peroxide biosensor was constructed by combining the advantageous properties of MWCNTs and Co{sub 3}O{sub 4}. • Incorporating Co{sub 3}O{sub 4} nanoparticles into MWCNTs/gelatin film increased the electron transfer. • Co{sub 3}O{sub 4}/MWCNTs/gelatin/HRP/Nafion/GCE showed strong anti-interference ability. • Hydrogen peroxide was successfully determined in disinfector with an average recovery of 100.78 ± 0.89. - Abstract: In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co{sub 3}O{sub 4} nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co{sub 3}O{sub 4} nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at −0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10{sup −7}–1.9 × 10{sup −5} M with a detection limit of 7.4 × 10{sup −7}. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89.

  12. Synthesis and CO{sub 2} adsorption study of modified MOF-5 with multi-wall carbon nanotubes and expandable graphite

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, Sami, E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Bustam, M. A., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Shariff, A. M., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Elkhalifah, Ali E. I., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Murshid, G., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Riaz, Nadia, E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com [Research Center for Carbon Dioxide Capture, Dept. of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, Tronoh 31750 Perak (Malaysia)

    2014-10-24

    MOF-5 was synthesized by solvothermal method and its reactivation under anhydrous conditions. This research is conducted to investigate the effect of MOF-5 and MOF-5 modified with multi-wall carbon nanotubes (MWCNTs) and expandable graphite (EG) on the performance of CO{sub 2} adsorption. The synthesized MOFs were characterized using Field emission scanning electron microscopy (FESEM) for surface morphology, Thermogravimetric analysis (TGA) for thermal stability, X-ray diffraction (XRD) for crystals plane, Brunauer-Emmet-Teller (BET) for surface area and CO{sub 2} adsorption. The result had showed that the modified MOF-5 enhanced the CO{sub 2} adsorption compared to the pure MOF-5. The increment in the CO{sub 2} uptake capacities of MOF materials was attributed to the decrease in the pore size and enhancement of micropore volume of MOF-5 by multi-walled carbon nanotube and EG incorporation. The BET surface area of the synthesized MOF-5@MWCNTs is more than MOF-5. The CO{sub 2} sorption capacities of MOF-5 and MOF-5@MWCNTs were observed to increase from 0.00008 to 0.00048 mol g-1 at 298 K and 1 bar. The modified MOF-5@MWCNTs resulted in the highest CO{sub 2} adsorption followed by the modified MOF-5@ EG and lastly, MOF-5.

  13. Zeta Potential of Modified Multi-walled Carbon Nanotubes in Presence of poly (vinyl alcohol) Hydrogel

    OpenAIRE

    de la Cruz, EF; Zheng, Y.; Torres, E; Li, W.; Song, W; Burugapalli, K

    2012-01-01

    The main objective of this study is investigate the behavior of the Zeta Potential of the MWCNT modified with SDS(Sodium Dodecyl Sulfate) and CTAB(Cetyl Tetraethyl Ammonium Bromide) in presence of PVA. Full hydrolyzed PVA was used. As a result, adding PVA in the CNT solution led to decrease the Zeta Potential. The Zeta Potential of suspended colloid varied from 42.00mV to 6.48mV and -45.00mV to -6.4mV at 1.5% concentration of PVA; according with the changing pH, the Zeta Potential dropped to ...

  14. A miniature glucose/O{sub 2} biofuel cell with single-walled carbon nanotubes-modified carbon fiber microelectrodes as the substrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xianchan; Zhou, Haojie [Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100080 (China); Graduate School of CAS, Beijing 100049 (China); Yu, Ping; Su, Lei; Mao, Lanqun [Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100080 (China); Ohsaka, Takeo [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

    2008-06-15

    This study demonstrates a new kind of miniature glucose/O{sub 2} biofuel cells (BFCs) based on carbon fiber microelectrodes (CFMEs) modified with single-walled carbon nanotubes (SWNTs). SWNTs are used as a support both for stably confining the electrocatalyst (i.e., methylene green, MG) for the oxidation of NADH and the anodic biocatalyst (i.e., NAD{sup +}-dependent glucose dehydrogenase, GDH) for the oxidation of glucose and for efficiently facilitating direct electrochemistry of the cathodic biocatalyst (i.e., laccase) for the O{sub 2} reduction. The prepared micro-sized GDH-based bioanode and laccase-based biocathode exhibit good bioelectrocatalytic activity toward the oxidation of glucose and the reduction of oxygen, respectively. In 0.10 M phosphate buffer containing 10 mM NAD{sup +} and 45 mM glucose under ambient air, the power density of the assembled miniature compartment-less glucose/O{sub 2} BFC reaches 58 {mu}W cm{sup -2} at 0.40 V. The stability of the miniature glucose/O{sub 2} BFC is also evaluated. (author)

  15. Lithium interaction with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Nalimova, V.A. [Moskovskij Gosudarstvennyj Univ., Moscow (Russian Federation). Khimicheskij Fakul`tet; Sklovsky, D.E. [Moskovskij Gosudarstvennyj Univ., Moscow (Russian Federation). Khimicheskij Fakul`tet; Bondarenko, G.N. [Topcheiv Institute of Petrochemical Synthesis, Leninsky Prospekt, 29, Moscow (Russian Federation); Alvergnat-Gaucher, H. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France); Bonnamy, S. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France); Beguin, F. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France)

    1997-05-01

    Lithium interaction with catalytic carbon nanotubes under high-pressure conditions was studied. A large amount of Li (2Li/C) reacted with the carbon nanotubes forming an intercalation compound (I{sub c}{proportional_to}4.1 A) which follows from X-ray diffraction and IR spectroscopy data. We cannot exclude also the possibility of insertion of a part of Li into the channel of the nanotubes. (orig.)

  16. Carbon nanotube Archimedes screws.

    Science.gov (United States)

    Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

    2010-12-28

    Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ≈1 pAmp.

  17. Non-covalent functionalization of single-walled carbon nanotubes with modified polyethyleneimines for efficient gene delivery.

    Science.gov (United States)

    Behnam, Behzad; Shier, Wayne T; Nia, Azadeh Hashem; Abnous, Khalil; Ramezani, Mohammad

    2013-09-15

    Functionalized carbon nanotubes (CNTs) have been recently emerged as important class of vectors for delivery of DNA and other biomolecules into various cells. In this study, single-walled carbon nanotubes (SWNTs) were functionalized by non-covalent binding of hydrophobic moieties, which were covalently linked to polyethyleneimines (PEIs). PEIs of three molecular weights (25, 10 and 1.8kDa) were used. CNTs were functionalized with the PEI series either through phospholipid moiety (via a polyethyleneglycol linker) or through directly-attached long (18 carbons) or intermediate (10 carbons) hydrophobic alkyl moieties. All PEI-functionalized CNTs exhibited good stability and dispersibility in biological media. Visualizing of functionalized CNTs and lack of aggregation were confirmed by atomic force microscopy. The PEI derivatives bound to CNTs retained the ability to fully condense plasmid DNA at low N/P ratios and substantial buffering capacity in the endosomal pH range. PEI-functionalized CNTs exhibited increased transfection efficiency compared to underivatized PEIs up to 19-fold increase being observed in the functionalized CNT with the smallest PEI tested, the smallest hydrophobic attachment moiety tested and no linker. Also PEI-functionalized CNTs were effective gene delivery vectors in vivo following tail vein injection in mice with the largest expression occurring with the vector PEI-functionalized through a polyethyleneglycol linker.

  18. Covalently {beta}-cyclodextrin modified single-walled carbon nanotubes: a novel artificial receptor synthesized by 'click' chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Guo Zhen; Liang Li [Nankai University, State Key Laboratory and Institute of Elemento-Organic Chemistry (China); Liang Jiajie; Ma Yanfeng; Yang Xiaoying [Nankai University, Center for Nanoscale Science and Technology and Institute of Polymer Chemistry, College of Chemistry (China); Ren Dongmei [Nankai University, State Key Laboratory and Institute of Elemento-Organic Chemistry (China); Chen Yongsheng [Nankai University, Center for Nanoscale Science and Technology and Institute of Polymer Chemistry, College of Chemistry (China); Zheng Jianyu, E-mail: jyzheng@nankai.edu.c [Nankai University, State Key Laboratory and Institute of Elemento-Organic Chemistry (China)

    2008-08-15

    Novel {beta}-cyclodextrin covalently modified single-walled carbon nanotubes have been synthesized via a 'click' coupling reaction. The product was fully characterized with Raman, FTIR, XRD, UV-Vis-NIR spectra as well as TEM and TGA measurements. The effective functionalization via 'click' coupling has set up a facile and versatile route for modular preparation of SWNTs based functional materials. The inclusion complexation behavior of this artificial receptor with quinine has been investigated in aqueous solution by fluorescence spectroscopy.

  19. Voltammetric determination of isoproterenol using a 5-amino-2′,4′-dimethoxybiphenyl-2-ol modified carbon nanotube paste electrode

    Institute of Scientific and Technical Information of China (English)

    Hadi Beitollahi; Hojatollah Khabazzadeh; Hassan Karimi-Maleh; Ali Akbari

    2012-01-01

    A new electrochemical sensor for determination ofisoproterenol (IP) is described.The sensor is based on carbon paste electrode (CPE) modified with 5-amino-2',4'-dimethoxybiphenyl-2-ol (5ADMB) and takes the advantages of carbon nanotubes (CNTs).Under the optimum pH of 7.0,the oxidation of IP occurs at a potential about 210 mV less positive than that of the unmodified CPE.The oxidation currents increased linearly with two concentration intervals of IP,one is 0.09 to 20.0 μmol/L and,the other is 20.0 to 400.0 μmol/L.The detection limit (3σ) obtained by square wave voltammetry (SWV) was 39.0 nmol/L.The practical application of the modified electrode was demonstrated by determining IP in IP ampoule,urine and human blood serum samples.

  20. Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Afraz, Ahmadreza [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Najafi, Mojgan [Department of Materials Engineering, Hamedan University of Technology (HUT), 65169 Hamedan (Iran, Islamic Republic of)

    2014-11-01

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450 μM, respectively, and with 120, 30 and 30 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. - Highlights: • New method for simultaneous determination of AA, DA and UA was developed. • MWCNT/ionic liquid/cauliflower-like Au nanostructure was used for CPE modification. • Optimization of electrode composition was done by Design-Expert software. • The pH effect, peak separation mechanism and real samples was thoroughly studied.

  1. The Long-Term Fate and Toxicity of PEG-Modified Single-Walled Carbon Nanotube Isoliquiritigenin Delivery Vehicles in Rats

    Directory of Open Access Journals (Sweden)

    Bo Han

    2014-01-01

    Full Text Available Oxidized single-walled carbon nanotubes (o-SWNTs was modified by covalently and noncovalently linking PEG to the o-SWNTs. The influence of oxidation time, PEG molecular weight, and type of PEG linkage on the blood clearance time of PEG-modified single-walled carbon nanotubes (SWNTs was investigated. The toxicity profile of SWNTs covalently linked to PEG (c-PEG-o-SWNTs in rats has also been determined. The pharmacokinetics of c-PEG-o-SWNTs in rats and their distribution in vital organs were monitored by Raman spectroscopy, and the blood clearance of homogenate isoliquiritigenin (ISL was determined by HPLC. Photos of tissue and tissue sections were taken to evaluate the toxicity of c-PEG-o-SWNTs. We found that SWNTs which were covalently modified with PEG and have a molecular weight of 3500 had the longest blood clearance half-lives. However, SWNTs were toxic to the kidneys and the hearts. The high renal clearance of long-term fate SWNTs may occur because of impaired kidney filtration function. Therefore, we assume that while researchers study the long-term fate of SWNTs, the toxicity of SWNTs also needs to be taken into account.

  2. Sol-gel derived multiwalled carbon nanotubes ceramic electrode modified with molecularly imprinted polymer for ultra trace sensing of dopamine in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Bhim Bali, E-mail: prof.bbpd@yahoo.com [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India); Kumar, Deepak; Madhuri, Rashmi; Tiwari, Mahavir Prasad [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India)

    2011-08-01

    Highlights: > MWCNTs-CE was prepared by silane acrylate which provides a nanometer thin MIP film. > The sensor was modified by iniferter and MIP using 'surface grafting-from approach'. > A comparative study was performed between differentially designed ceramic electrodes. > The sensor can detect dopamine in real samples with LODs (0.143-0.154 ng mL{sup -1}). - Abstract: A new class of composite electrodes made of sol-gel derived ceramic-multiwalled carbon nanotubes is used for the growth of a nanometer thin film adopting 'surface grafting-from approach'. For this the multiwalled carbon nanotubes-ceramic electrode surface is first modified with an iniferter (benzyl N,N-diethyldithiocarbamate) and then dopamine imprinted polymer, under UV irradiation, for differential pulse anodic stripping voltammetric sensing of dopamine in aqueous, blood serum, cerebrospinal fluid, and pharmaceutical samples (detection limit 0.143-0.154 ng mL{sup -1}, 3{sigma}), without any cross reactivity, interferences and false-positive contributions. Such composite electrodes offer higher stability, electron kinetics, and renewable porous surface of larger electroactive area (with insignificant capacitance) than carbon ceramic electrodes. Additional cyclic voltammetry (stripping mode) and chronocoulometry experiments were performed to explore electrodics and kinetics of electro-oxidation of dopamine.

  3. Carbon Nanotubes and Modern Nanoagriculture

    KAUST Repository

    Bayoumi, Maged Fouad

    2015-01-27

    Since their discovery, carbon nanotubes have been prominent members of the nanomaterial family. Owing to their extraordinary physical, chemical, and mechanical properties, carbon nanotubes have been proven to be a useful tool in the field of plant science. They were frequently perceived to bring about valuable biotechnological and agricultural applications that still remain beyond experimental realization. An increasing number of studies have demonstrated the ability of carbon nanotubes to traverse different plant cell barriers. These studies, also, assessed the toxicity and environmental impacts of these nanomaterials. The knowledge provided by these studies is of practical and fundamental importance for diverse applications including intracellular labeling and imaging, genetic transformation, and for enhancing our knowledge of plant cell biology. Although different types of nanoparticles have been found to activate physiological processes in plants, carbon nanotubes received particular interest. Following addition to germination medium, carbon nanotubes enhanced root growth and elongation of some plants such as onion, cucumber and rye-grass. They, also, modulated the expression of some genes that are essential for cell division and plant development. In addition, multi-walled carbon nanotubes were evidenced to penetrate thick seed coats, stimulate germination, and to enhance growth of young tomato seedlings. Multi-walled carbon nanotubes can penetrate deeply into the root system and further distribute into the leaves and the fruits. In recent studies, carbon nanotubes were reported to be chemically entrapped into the structure of plant tracheary elements. This should activate studies in the fields of plant defense and wood engineering. Although, all of these effects on plant physiology and plant developmental biology have not been fully understood, the valuable findings promises more research activity in the near future toward complete scientific understanding of

  4. Studies of Carbon Nanotubes

    Science.gov (United States)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  5. Role of carbon nanotubes in electroanalytical chemistry: a review.

    Science.gov (United States)

    Agüí, Lourdes; Yáñez-Sedeño, Paloma; Pingarrón, José M

    2008-08-01

    This review covers recent advances in the development of new designs of electrochemical sensors and biosensors that make use of electrode surfaces modification with carbon nanotubes. Applications based on carbon nanotubes-driven electrocatalytic effects, and the construction and analytical usefulness of new hybrid materials with polymers or other nanomaterials will be treated. Moreover, electrochemical detection using carbon nanotubes-modified electrodes as detecting systems in separation techniques such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) will be also considered. Finally, the preparation of electrochemical biosensors, including enzyme electrodes, immunosensors and DNA biosensors, in which carbon nanotubes play a significant role in their sensing performance will be separately considered.

  6. Apparatus for the laser ablative synthesis of carbon nanotubes

    Science.gov (United States)

    Smith, Michael W.; Jordan, Kevin

    2010-02-16

    An RF-induction heated side-pumped synthesis chamber for the production of carbon nanotubes. Such an apparatus, while capable of producing large volumes of carbon nanotubes, concurrently provides a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization.

  7. Carbon Nanotubes for Space Applications

    Science.gov (United States)

    Meyyappan, Meyya

    2000-01-01

    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  8. Luminescence of carbon nanotube bulbs

    Institute of Scientific and Technical Information of China (English)

    LI ChuanGang; WU DeHai; WANG KunLin; WEI JinQuan; WEI BingQing; ZHU HongWei; WANG ZhiCheng; LUO JianBin; LIU WenJin; ZHENG MingXin

    2007-01-01

    Carbon nanotube (CNT) bulbs made of decimeter-scale double-walled carbon nanotube (DWCNT) strands and films were fabricated and their luminescence properties, including the lighting efficiency, voltage-current relation and thermal stability were investigated. The results show that the DWCNT bulb has a comparable spectrum of visible light with tungsten bulb and its average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400-2300 K). The nanotube filaments show both resistance and thermal stability over a large temperature region. No obvious damage was found for a nanotube bulb illuminating at 2300 K for more than 24 hours in vacuum.

  9. A Novel Soluble Tin(IV Porphyrin Modified Single-Walled Carbon Nanotube Nanohybrid With Light Harvesting Properties

    Directory of Open Access Journals (Sweden)

    Jian-Yu Zheng

    2008-01-01

    Full Text Available A dihydroxotin(IV porphyrin functionalized single-walled carbon nanotubes (SWNTs nanohybrid is obtained. Solubility of the nanohybrid in organic solvents is determined by UV-Vis-NIR absorption spectroscopy. Electron absorption and fluorescence spectra investigations demonstrate that efficient electron transfer occurs within the nanohybrid at the photoexcited state and the charge-separated state of the nanohybrid is observed by transient absorption spectrum. The results illustrate that this soluble electron donor–acceptor nanohybrid might be a good candidate as a light harvesting material in molecular photoelectronic devices.

  10. Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

    Science.gov (United States)

    Yan, Yibo; Miao, Jianwei; Yang, Zhihong; Xiao, Fang-Xing; Yang, Hong Bin; Liu, Bin; Yang, Yanhui

    2015-05-21

    Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid-base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.

  11. Highly sensitive amperometric sensor for micromolar detection of trichloroacetic acid based on multiwalled carbon nanotubes and Fe(II)–phtalocyanine modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kurd, Masoumeh [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2013-04-01

    A highly sensitive electrochemical sensor for the detection of trichloroacetic acid (TCA) is developed by subsequent immobilization of phthalocyanine (Pc) and Fe(II) onto multiwalled carbon nanotubes (MWCNTs) modified glassy carbon (GC) electrode. The GC/MWCNTs/Pc/Fe(II) electrode showed a pair of well-defined and nearly reversible redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) with surface-confined characteristics. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k{sub s}) of immobilized Fe(II)–Pc were calculated as 1.26 × 10{sup −10} mol cm{sup −2} and 28.13 s{sup −1}, respectively. Excellent electrocatalytic activity of the proposed GC/MWCNTs/Pc/Fe(II) system toward TCA reduction has been indicated and the three consequent irreversible peaks for electroreduction of CCl{sub 3}COOH to CH{sub 3}COOH have been clearly seen. The observed chronoamperometric currents are linearly increased with the concentration of TCA at concentration range up to 20 mM. Detection limit and sensitivity of the modified electrode were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively. The applicability of the sensor for TCA detection in real samples was tested. The obtained results suggest that the proposed system can serve as a promising electrochemical platform for TCA detection. Highlights: ► Phthalocyanine (PC) and Fe(II) immobilized onto MWCNTs modified GC electrode. ► A pair of well-defined redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) observed. ► Modified electrode shows excellent catalytic activity to electroreduction of CCl{sub 3}COOH. ► Amperometry and cyclic voltammetry techniques were used for detection of CCl{sub 3}COOH. ► Detection limit and sensitivity were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively.

  12. Laser ablative synthesis of carbon nanotubes

    Science.gov (United States)

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  13. Carbon Nanotube Biosensors

    Directory of Open Access Journals (Sweden)

    Carmen-Mihaela eTilmaciu

    2015-10-01

    Full Text Available Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  14. Carbon nanotube biosensors

    Science.gov (United States)

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  15. Site-selective radiation damage of collapsed carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, V.H. [Department of Physics, 104 Davey Lab, The Pennsylvania State University, University Park, Pennsylvania 16802-6300 (United States); Chopra, N.G.; Cohen, M.L.; Zettl, A. [Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Radmilovic, V. [Department of Physical Metallurgy, University of Belgrade Karnegijeva 4, P.O. Box 494, Belgrade, 11001 (Yugoslavia)

    1998-10-01

    Carbon nanotubes can flatten into collapsed tubes with bulbs along either edge. The strong anisotropy in the graphitic radiation damage threshold both explains the rapid destruction of face-on flattened nanotubes and can be exploited to selectively modify the structure of edge-on flattened nanotubes, thereby creating one-dimensional sp{sup 2} carbon with noncontinuous transverse boundary conditions. {copyright} {ital 1998 American Institute of Physics.}

  16. Atomic transportation via carbon nanotubes.

    Science.gov (United States)

    Wang, Quan

    2009-01-01

    The transportation of helium atoms in a single-walled carbon nanotube is reported via molecular dynamics simulations. The efficiency of the atomic transportation is found to be dependent on the type of the applied loading and the loading rate as well as the temperature in the process. Simulations show the transportation is a result of the van der Waals force between the nanotube and the helium atoms through a kink propagation initiated in the nanotube.

  17. Modifying the poly ether ester antistatic agent by carbon nanotubes,the antistatic effect on polypropylene fibers

    Institute of Scientific and Technical Information of China (English)

    LI Chensha; LI Zhi; ZHANG Baoyou; LU Weizhe; TANG Yaping; FANG Gang; HU Xiaoqing; LIANG Ji

    2004-01-01

    A new antistatic fiber is investigated using carbon nanotubes (CNTs) to enhance the antistatic ability of polymer fibers based on the mechanism of the discharging process of polarity macromolecule. Composite antistatic agent (CAA), prepared by dispersing CNTs in an organic antistatic agent carrier containing metallic ions in their main chains, is cospun with polypropylene (PP) to prepare CAA/PP fibers. It is indicated through analyzing the measured dynamic tribo-electrostatic voltages that CNTs can promote the discharging process of polarity macromolecule of antistatic agent carrier and further improve the antistatic ability of PP fibers. It is also indicated that the antistatic effect promoted by CNTs is better than that by conductive carbon black. Moreover, the antistatic effects of the CNTs treated by different methods are also compared.

  18. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    Directory of Open Access Journals (Sweden)

    Hayati Filik

    2016-05-01

    Full Text Available In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified electrodes. The modified electrode showed excellent electrocatalytic activity toward ascorbic acid, dopamine, uric acid, and tryptophan (pH 7.0. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA and Trp were 300–10,000 μM, 0.5–50 μM, 0.5–50 μM and 1.0–100 μM, respectively, and the detection limits were 16 μM, 0.014 μM, 0.028 μM and 0.56 μM (S/N = 3. The proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules. The procedure was also applied to the determination of tryptophan in spiked milk samples.

  19. Method for synthesizing carbon nanotubes

    Science.gov (United States)

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  20. A review on protein functionalized carbon nanotubes.

    Science.gov (United States)

    Nagaraju, Kathyayini; Reddy, Roopa; Reddy, Narendra

    2015-12-18

    Carbon nanotubes (CNTs) have been widely recognized and used for controlled drug delivery and in various other fields due to their unique properties and distinct advantages. Both single-walled carbon nanotubes (SWCNTs) and multiwalled (MWCNTs) carbon nanotubes are used and/or studied for potential applications in medical, energy, textile, composite, and other areas. Since CNTs are chemically inert and are insoluble in water or other organic solvents, they are functionalized or modified to carry payloads or interact with biological molecules. CNTs have been preferably functionalized with proteins because CNTs are predominantly used for medical applications such as delivery of drugs, DNA and genes, and also for biosensing. Extensive studies have been conducted to understand the interactions, cytotoxicity, and potential applications of protein functionalized CNTs but contradicting results have been published on the cytotoxicity of the functionalized CNTs. This paper provides a brief review of CNTs functionalized with proteins, methods used to functionalize the CNTs, and their potential applications.

  1. Carbon nanotubes: engineering biomedical applications.

    Science.gov (United States)

    Gomez-Gualdrón, Diego A; Burgos, Juan C; Yu, Jiamei; Balbuena, Perla B

    2011-01-01

    Carbon nanotubes (CNTs) are cylinder-shaped allotropic forms of carbon, most widely produced under chemical vapor deposition. They possess astounding chemical, electronic, mechanical, and optical properties. Being among the most promising materials in nanotechnology, they are also likely to revolutionize medicine. Among other biomedical applications, after proper functionalization carbon nanotubes can be transformed into sophisticated biosensing and biocompatible drug-delivery systems, for specific targeting and elimination of tumor cells. This chapter provides an introduction to the chemical and electronic structure and properties of single-walled carbon nanotubes, followed by a description of the main synthesis and post-synthesis methods. These sections allow the reader to become familiar with the specific characteristics of these materials and the manner in which these properties may be dependent on the specific synthesis and post-synthesis processes. The chapter ends with a review of the current biomedical applications of carbon nanotubes, highlighting successes and challenges.

  2. An Effective Approach towards the Immobilization of PtSn Nanoparticles on Noncovalent Modified Multi-Walled Carbon Nanotubes for Ethanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2016-03-01

    Full Text Available In this article, we describe an effective method to tether Pt and PtSn nanoparticles (NPs on polyelectrolyte modified multi-walled carbon nanotubes (MWCNTs for ethanol electrooxidation. By using a polymer wrapping technique, positively charged polyethyleneimine (PEI was attached onto carbon nanotubes (CNTs to provide preferential linking sites for metal precursors. Well-dispersed Pt and PtSn nanocrystals (2–5 nm were subsequently decorated on PEI-functionalized MWCNTs through the polyol reduction method. The successful non-covalent modification of MWCNTs was confirmed by Fourier transform infrared spectroscopy (FTIR and Zeta potential measurements. Energy dispersive X-ray (EDX spectrum indicates approximately 20 wt % Pt loading and a desirable Pt:Sn atomic ratio of 1:1. Electrochemical analysis demonstrated that the as-synthesized PtSn/PEI-MWCNTs nanocomposite exhibited improved catalytic activity and higher poison tolerance for ethanol oxidation as compared to Pt/PEI-MWCNTs and commercial Pt/XC-72 catalysts. The enhanced electrochemical performance may be attributed to the uniform dispersion of NPs as well as the mitigating of CO self-poisoning effect by the alloying of Sn element. This modification and synthetic strategy will be studied further to develop a diversity of carbon supported Pt-based hybrid nanomaterials for electrocatalysis.

  3. Green-tea modified multiwalled carbon nanotubes for efficient poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate)/n-silicon hybrid solar cell

    Science.gov (United States)

    Khatri, Ishwor; Tang, Zeguo; Liu, Qiming; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime

    2013-02-01

    Poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS)/n-Si hybrid solar cells were studied with and without embedding green-tea modify multiwalled carbon nanotubes (MWCNTs) at interface. Devices fabricated with embedding green-tea modified MWCNTs show much better performance than that of a device without MWCNTs with short circuit current density (Jsc), open circuit voltage (Voc), fill factor, and power conversion efficiency (η) as 30.31 mA/cm2, 0.54 V, 0.66, and 10.93%, respectively. Here, we believe that green-tea disperse MWCNTs bundles to individual and its incorporation improved built-in potential (Vb) of the device for better hole transport, easy exciton splitting, and suppression of charge recombination, thereby improving photovoltaic response.

  4. Electrocatalytic determination of L-cysteine using a modified carbon nanotube paste electrode: Application to the analysis of some real samples

    Institute of Scientific and Technical Information of China (English)

    Malihe Ahmadipour; Mohammad Ali Taher; Hadi Beitollahi; Rahman Hosseinzadeh

    2012-01-01

    The electrooxidation of L-cysteine (L-Cys) was studied using a benzoylferrocene (BF) modified multi-wall carbon nanotube paste electrode (BFCNPE) using cyclic voltammetry (CV),square wave voltammetry (SWV) and chronoamperometry (CHA).Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode.The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linearcalibration curve was obtained in the range 0.7-350.0 μmol/L of L-Cys with SWV method.The detection limit (3σ) was determined as 0.1 μmolL.This method was also used for the determination of L-Cys in some real samples.

  5. Corrosion protection of cold-rolled steel with alkyd paint coatings composited with submicron-structure types polypyrrole-modified nano-size alumina and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Gergely, Andras, E-mail: andras.gergely@ttk.mta.hu [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Paszti, Zoltan; Hakkel, Orsolya; Drotar, Eszter [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Mihaly, Judith [Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary); Kalman, Erika [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest (Hungary)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer Alumina/carbon nanotube (CNT) supported polypyrrole (PPy) particles were prepared. Black-Right-Pointing-Pointer Various paint compositions with alkyd binder were immersion tested. Black-Right-Pointing-Pointer Alumina-supported PPy based coating provided steel protection in NaCl solution. Black-Right-Pointing-Pointer Polyelectrolyte modified CNT embedded coating afforded long-term stable protection. Black-Right-Pointing-Pointer sulphonated CNT loaded coating indicated firm corrosion resistance in HCL solution. Black-Right-Pointing-Pointer Results are interpreted on the basis of nano and microstructure of the particles. - Abstract: This paper is focused on studying corrosion protection of cold-rolled steel with alkyd paint coatings comprising nano-size alumina and either polystyrene-sulphonate (PSS) modified or sulphonated multi-walled carbon nanotube (MWCNT) supported polypyrrole (PPy). Single layer coatings (in thickness of 40 {+-} 5 {mu}m) comprising PPy deposited alumina and PSS modified MWCNT supported PPy afforded viable protection during the 1 M sodium chloride test. The coatings containing PSS modified and weakly sulphonated MWCNTs (at volume fractions of 9.9 Multiplication-Sign 10{sup -4} and 2.5 Multiplication-Sign 10{sup -4}) with PPy volume fractions of 3.5 Multiplication-Sign 10{sup -3} and 2.5 Multiplication-Sign 10{sup -3} provided effective corrosion prevention during the 1 M sodium chloride and hydrochloric acid solution tests. While inhibitor particles were characterised by infrared spectroscopy, corrosion products formed at the paint-steel interface were studied by X-ray photoelectron spectroscopy. Apart from the electron microscopy observations, rheology study of three-dimensional structure of the inhibitor particles was performed in dispersions at similar compositions to those used for the paint formulations. Thus, protection mechanism relating to both types of immersion tests is discussed in terms of

  6. 碳纳米管改性涂料的防腐性能研究%Study on Corrosion Resistance of Coating Modified by Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    程敬泉; 乔磊; 黄海祥

    2015-01-01

    采用浓酸氧化法对碳纳米管进行表面改性,在 40 ℃超声波分散条件下,制备碳纳米管/环氧树脂复合涂料.通过对未加入碳纳米管、加入未经过浓酸氧化的碳纳米管、加入浓酸氧化的碳纳米管环氧树脂复合涂料进行耐酸碱盐试验.试验表明,加入未处理的碳纳米管的环氧树脂复合涂料防腐性能较纯净的环氧树脂涂料没有明显提高,加入浓酸氧化的碳纳米管环氧树脂防腐性能有了明显改善和提高.%Modifying the surface of multi-walled carbon nanotubes (MWCNTS) with concentrated sulfuric acid (H2SO4 / HNO3) oxidation. At 40℃ ultrasonic dispersion, prepare carbon nanotubes (MWCNTS) / epoxy resin composites. The anti-acid, anti-alkali and anti-salt tests of epoxy resin composite materials are carried out, first without MWCNTS, then with MWCNTS which are not oxidated with concentrated sulfuric acid, and then with MWCNTS which are oxidated with concentrated sulfuric acid. Experiments show that, the anticorrosive performance of epoxy resin composite materials with untreated carbon nanotubes are not obviously higher than the pure epoxy resin composite materials; the anticorrosive performance of epoxy resin composite materials with MWCNTS which are oxidated with concentrated sulfuric acid has been significantly improved and enhanced.

  7. Functionalization of Carbon Nanotubes

    Science.gov (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  8. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  9. Carbon nanotube biconvex microcavities

    Science.gov (United States)

    Butt, Haider; Yetisen, Ali K.; Ahmed, Rajib; Yun, Seok Hyun; Dai, Qing

    2015-03-01

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2-3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  10. Enhanced Carbon Nanotube Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  11. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K;

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individua...

  12. Molybdenum Disulfide Sheathed Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xu Chun SONG; Zhu De XU; Yi Fan ZHENG; Gui HAN; Bo LIU; Wei Xiang CHEN

    2004-01-01

    Single and double layered MoS2-coated multiwalled carbon nanotubes (MWCNs) were successfully prepared by pyrolyzing (NH4)2MoS4-coated multiwalled carbon nanotubes in an H2 atmosphere at 900℃. MoS2-coated MWCNs would be expected to have different tribological and mechanical properties compared to MoS2, so it may have potential applications in many fields.

  13. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  14. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual......, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications....

  15. Effect of Co-polyester antistatic agent modified by carbon nanotubes on the properties of polypropylene fibers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Antistatic polymer fibers were investigated by using carbon nanotubes (CNTs) to enhance the antistatic ability of inner antistatic agents based on the mechanism of attracting moisture by polar radical groups. It is indicated that the antistatic ability of the fibers filled with composite antistatic agents that contain CNTs and organic antistatic agents was superior to that of the fibers filled either with pure organic antistatic agents or pure CNTs. The antistatic ability of the composite antistatic agent fabricated by an in situ process was superior to that of the composite antistatic agent fabricated by direct dispersing CNTs in the antistatic agent carrier.Moreover, the heat-treated CNTs could further enhance the antistatic effect compared with the initial CNTs. The antistatic effect is significantly influenced by the content of CNTs in the composite antistatic agent.

  16. Prestrain relaxation in non-covalently modified ethylene-vinyl acetate | PyChol | multiwall carbon nanotube nanocomposites

    Directory of Open Access Journals (Sweden)

    A. D. Winter

    2014-06-01

    Full Text Available Effects of aging on chemical structure and molecular dynamic behaviour of strained thermally active ethylene-vinyl acetate | multiwall carbon nanotube (EVA|MWCNT composites were investigated by spectroscopy and microscopy techniques. Aged composites showed spatial inhomogeneity due to system relaxation. Inhomogeneity is attributed to segregation of non-covalently linked cholestryl 1-pyrenecarboxylate, acting as MWCNT dispersant and polymer compatibilizer. Analysis of molecular interplay between filler and matrix upon in situ temperature variation showed a lack of synchronicity, which had been observed in fresh composites. Reduced synchronous interplay allowed quantification of degraded π-π interactions, promoting PyChol unlatching as a result of both sonication and strained-derived π-π degradation.

  17. Biomimetic sensor based on hemin/carbon nanotubes/chitosan modified microelectrode for nitric oxide measurement in the brain.

    Science.gov (United States)

    Santos, Ricardo M; Rodrigues, Marcelo S; Laranjinha, João; Barbosa, Rui M

    2013-06-15

    A novel biomimetic microsensor for measuring nitric oxide (NO) in the brain in vivo was developed. The sensor consists of hemin and functionalized multi-wall carbon nanotubes covalently attached to chitosan via the carbodiimide crosslinker EDC followed by chitosan electrodeposition on the surface of carbon fiber microelectrodes. Cyclic voltammetry supported direct electron transfer from the Fe(III)/Fe(II) couple of hemin to the carbon surface at -0.370 V and -0.305 V vs. Ag/AgCl for cathodic and anodic peaks, respectively. Square wave voltammetry revealed a NO reduction peak at -0.762 V vs. Ag/AgCl that increased linearly with NO concentration between 0.25 and 1 μM. The average sensitivity of the microsensors was 1.72 nA/μM and the limit of detection was 25 nM. Oxygen and hydrogen peroxide reduction peaks were observed at -0.269 V and -0.332 V vs. Ag/AgCl, respectively and no response was observed for other relevant interferents, namely ascorbate, nitrite and dopamine. The microsensor was successfully applied to the measurement of exogenously applied NO in the rat brain in vivo.

  18. Microfabricated electroactive carbon nanotube actuators

    Science.gov (United States)

    Ahluwalia, Arti; Baughman, Ray H.; De Rossi, Danilo; Mazzoldi, Alberto; Tesconi, Mario; Tognetti, Alessandro; Vozzi, Giovanni

    2001-07-01

    A variety of microfabrication techniques have been developed at the University of Pisa. They are based either on pressure or piston actuated microsyringes or modified ink-jet printers. This work present the results of a study aimed at fabricating carbon nanotube (NT) actuators using micro-syringes. In order to prevent the nanotubes from aggregating into clumps, they were enclosed in a partially cross-linked polyvinylalcohol - polyallylamine matrix. After sonication the solution remained homogenously dispersed for about 40 minutes, which was sufficient time for deposition. Small strips of NT, about 5 mm across and 15 mm long were deposited. Following deposition, the films were baked at 80 degree(s)C and their thickness, impedance and mechanical resistance measured. The results indicate that 50 minutes of baking time is sufficient to give a constant resistivity of 1.12 x 10-2 (Omega) m per layer similar to a typical semiconductor, and each layer has a thickness of about 6 micrometers .

  19. Oxidation of 2,4-dichlorophenol by non-radical mechanism using persulfate activated by Fe/S modified carbon nanotubes.

    Science.gov (United States)

    Cheng, Xin; Guo, Hongguang; Zhang, Yongli; Liu, Yang; Liu, Hongwei; Yang, Ying

    2016-05-01

    The aim of this study was to develop a new approach for the activation of persulfate (PS) based on carbon nanotubes (CNTs). Fe/S modified carbon nanotubes (Fe/S-CNTs) were synthesized via impregnation-precipitation in the aqueous-phase synthesis method. The morphologies and chemical states of the catalysts were characterized and 2,4-dichlorophenol (2,4-DCP) was selected to investigate the degradation performance using Fe/S-CNTs with PS. The results reveal that the Fe/S-CNTs catalysts can significantly accelerate the removal of 2,4-DCP compared to single PS or PS/CNTs. The catalytic capacity is also enhanced by S modification and is affected by the solution pH. The iron loading content, PS concentration and catalyst dosage could play important roles in the degradation. A non-radical process of 2,4-DCP degradation is demonstrated for the first time in the results of the radical scavengers and chloride ionic, as well as persulfate decomposition. It is suggested that PS is first bonded with the sp(2)-hybridized system and activated by iron oxide particles and iron-sulfur complexes, then it reacts rapidly with the adsorbed 2,4-DCP.

  20. A novel magnetic ionic liquid modified carbon nanotube for the simultaneous determination of aryloxyphenoxy-propionate herbicides and their metabolites in water

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Mai; Liu, Donghui; Zhao, Lu; Han, Jiajun; Liang, Yiran; Wang, Peng; Zhou, Zhiqiang, E-mail: zqzhou@cau.edu.cn

    2014-12-10

    Highlights: • A new kind of ionic liquid modified carbon nanotube has been synthesized and applied for simultaneous analysis of AOPPs and their metabolites. • The potential pollutants, such as metabolites of AOPPs, have been analyzed. • The mechanism of absorption has been discussed. • Varieties of experiment factors were optimized and selected. • This method has been successfully applied in the analysis of real water samples. - Abstract: A reliable, sensitive, rapid and environmentally friendly analysis procedure for the simultaneous determination of the analytes with a wide range of polarity in the environmental water was developed by coupling dispersive magnetic solid-phase extraction (d-MSPE) with high-performance liquid chromatography (HPLC)–diode array detector (DAD) and ultra-high pressure liquid chromatography (UHPLC)-triple quadrupole mass spectrometer (MS/MS), in this work. Magnetic ionic liquid modified multi-walled carbon nanotubes (m-IL-MWCNTs) were prepared by spontaneous assembly of magnetic nanoparticles and imidazolium-modified carbon nanotubes, and used as the sorbent of d-MSPE to simultaneously extract aryloxyphenoxy-propionate herbicides (AOPPs) and their polar acid metabolites due to the excellent π–π electron donor–acceptor interactions and anion exchange ability. The factors, including the amount of sorbent, pH of the sample solution, extraction time and the volume of elution solvent were investigated. Under the optimized conditions, the proposed d-MSPE coupling to HPLC–DAD system had a satisfactory performance, the limits of detection (LODs, defined as the signal to noise ratio of 3) and the limits of quantification (LOQs, defined as the signal to noise ratio of 10) for analytes in Milli-Q water were in the range of 2.8–14.3 and 9.8–43.2 μg L{sup −1} respectively. Calibration curves were linear (r{sup 2} > 0.998) over the concentration range from 0.02 to 1 mg L{sup −1}. The recoveries of the eight analytes ranged

  1. Properties of Carbon Nanotubes

    Science.gov (United States)

    Masood, Samina; Bullmore, Daniel; Duran, Michael; Jacobs, Michael

    2012-10-01

    Different synthesizing methods are used to create various nanostructures of carbon; we are mainly interested in single and multi-wall carbon nanotubes, (SWCNTs) and (MWCNTs) respectively. The properties of these tubes are related to their synthetic methods, chirality, and diameter. The extremely sturdy structure of CNTs, with their distinct thermal and electromagnetic properties, suggests a tremendous use of these tubes in electronics and medicines. Here, we analyze various physical properties of SWCNTs with a special emphasis on electromagnetic and chemical properties. By examining their electrical properties, we demonstrate the viability of discrete CNT based components. After considering the advantages of using CNTs over microstructures, we make a case for the advancement and development of nanostructures based electronics. As for current CNT applications, it's hard to overlook their use and functionality in the development of cancer treatment. Whether the tubes are involved in chemotherapeutic drug delivery, molecular imaging and targeting, or photodynamic therapy, we show that the remarkable properties of SWCNTs can be used in advantageous ways by many different industries.

  2. Carbon nanotube computer.

    Science.gov (United States)

    Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

    2013-09-26

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems.

  3. Carbon Nanotube Purification

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  4. Influence of acid functionalization on the cardio-pulmonary toxicity of carbon nanotubes and carbon black in mice

    Science.gov (United States)

    Engineered carbon nanotubes are being developed for a wide range of industrial and medical applications. Because of their unique properties, nanotubes can impose potentially toxic effects, particularly if they have been modified to express functionally reactive chemical groups o...

  5. CO2 Removal from Biogas Using Carbon Nanotubes Mixed Matrix Membranes

    OpenAIRE

    Tutuk Djoko Kusworo; Ahmad Fauzi Ismail; Budiyono; I Nyoman Widiasa; Seno Johari; Sunarso

    2010-01-01

    A new type of mixed matrix membrane consisting of polyethersulfone (PES) and carbon nanotubes (CNTs) is prepared for biogas purification application. PES mixed matrix membrane with and without modification of carbon nanotubes were prepared by a dry/wet phase inversion technique using a pneumatically membrane casting machine system. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using acid treatment to allow PES chains to be grafted on c...

  6. Simultaneous trace-levels determination of Hg(II) and Pb(II) ions in various samples using a modified carbon paste electrode based on multi-walled carbon nanotubes and a new synthesized Schiff base

    Energy Technology Data Exchange (ETDEWEB)

    Afkhami, Abbas, E-mail: afkhami@basu.ac.ir [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Bagheri, Hasan [Department of Chemistry, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Khoshsafar, Hosein [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Saber-Tehrani, Mohammad [Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Tabatabaee, Masoumeh [Department of Chemistry, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Shirzadmehr, Ali [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of)

    2012-10-09

    Highlights: Black-Right-Pointing-Pointer A new chemically modified carbon paste electrode was constructed and used. Black-Right-Pointing-Pointer A new Schiff base and multi-walled carbon nanotube was used as a modifier. Black-Right-Pointing-Pointer The electrochemical properties of the modified electrode were studied. Black-Right-Pointing-Pointer The electrode was used to the simultaneous determination of Pb{sup 2+} and Hg{sup 2+}. - Abstract: A modified carbon paste electrode based on multi-walled carbon nanotubes (MWCNTs) and 3-(4-methoxybenzylideneamino)-2-thioxothiazolodin-4-one as a new synthesized Schiff base was constructed for the simultaneous determination of trace amounts of Hg(II) and Pb(II) by square wave anodic stripping voltammetry. The modified electrode showed an excellent selectivity and stability for Hg(II) and Pb(II) determinations and for accelerated electron transfer between the electrode and the analytes. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as pH, deposition potential and deposition time were optimized for the purpose of determination of traces of metal ions at pH 3.0. Under optimal conditions the limits of detection, based on three times the background noise, were 9.0 Multiplication-Sign 10{sup -4} and 6.0 Multiplication-Sign 10{sup -4} {mu}mol L{sup -1} for Hg(II) and Pb(II) with a 90 s preconcentration, respectively. In addition, the modified electrode displayed a good reproducibility and selectivity, making it suitable for the simultaneous determination of Hg(II) and Pb(II) in real samples such as sea water, waste water, tobacco, marine and human teeth samples.

  7. Carbon nanotubes as optical biomedical sensors.

    Science.gov (United States)

    Kruss, Sebastian; Hilmer, Andrew J; Zhang, Jingqing; Reuel, Nigel F; Mu, Bin; Strano, Michael S

    2013-12-01

    Biosensors are important tools in biomedical research. Moreover, they are becoming an essential part of modern healthcare. In the future, biosensor development will become even more crucial due to the demand for personalized-medicine, point-of care devices and cheaper diagnostic tools. Substantial advances in sensor technology are often fueled by the advent of new materials. Therefore, nanomaterials have motivated a large body of research and such materials have been implemented into biosensor devices. Among these new materials carbon nanotubes (CNTs) are especially promising building blocks for biosensors due to their unique electronic and optical properties. Carbon nanotubes are rolled-up cylinders of carbon monolayers (graphene). They can be chemically modified in such a way that biologically relevant molecules can be detected with high sensitivity and selectivity. In this review article we will discuss how carbon nanotubes can be used to create biosensors. We review the latest advancements of optical carbon nanotube based biosensors with a special focus on near-infrared (NIR)-fluorescence, Raman-scattering and fluorescence quenching.

  8. Electrodeposition of palladium on carbon nanotubes modified nickel foam as an efficient electrocatalyst towards hydrogen peroxide reduction

    Science.gov (United States)

    Yang, Fan; Cao, Bo; Tao, Yue; Hu, Miao; Feng, Chengcheng; Wang, Lei; Jiang, Zhao; Cao, Dianxue; Zhang, Ying

    2015-12-01

    In this article, a three-dimensional electrode (Pd-CNT/Ni foam) based on Pd nanoparticles and carbon nanotubes (CNTs) is successfully developed by a simple "dipping and drying" process and a potentiostatic deposition technology for H2O2 reduction in base medium. The composition and structure of Pd-CNT/Ni foam electrode are examined by X-ray diffractometer, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, respectively. The cyclic voltammetry (CV) and chronoamperometry (CA) techniques are applied to determine the electrochemical performance. The electrode exhibits a high catalytic activity for H2O2 electroreduction, and it outperforms Pd/Ni foam electrode without CNT coating. At the reduction potential of -0.8 V, the reduction currents on Pd-CNT/Ni foam electrode can reach 323 mA cm-2, however, it is only 192 mA cm-2 on Pd/Ni foam electrode, which is increased by 68.2%. The impressive electrocatalytic performance is largely attributed to the superior open structure and high electronic conductivity, which allows the high utilization of Pd surfaces and makes the electrode have higher electrochemical activity. These findings may provide the opportunity on preparing binder-free carbon-supported electrode in the application of fuel cells.

  9. Hydrogen peroxide biosensor based on gold nanoparticles/thionine/gold nanoparticles/multi-walled carbon nanotubes-chitosans composite film-modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li Shenfeng; Zhu Xiaoying; Zhang Wei; Xie Guoming [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China); Feng Wenli, E-mail: fengwlcqmu@sina.com [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China)

    2012-01-15

    In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H{sub 2}O{sub 2}), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au-S or Au-N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H{sub 2}O{sub 2} detection. The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 5 Multiplication-Sign 10{sup -7} mol L{sup -1} to 1.5 Multiplication-Sign 10{sup -3} mol L{sup -1} with a detection limit of 3.75 Multiplication-Sign 10{sup -8} mol L{sup -1} (based on S/N = 3).

  10. The fabrication and tribological behavior of epoxy composites modified by the three-dimensional polyurethane sponge reinforced with dopamine functionalized carbon nanotubes

    Science.gov (United States)

    Wang, Rui; Wang, Huaiyuan; Sun, Liyuan; Wang, Enqun; Zhu, Yixing; Zhu, Yanji

    2016-01-01

    Three-dimensional (3D) interpenetrating network structure epoxy composites were fabricated based on the modified carbon nanotube (CNT) reinforced flexible polyurethane (PU) sponge. CNTs were first functionalized with polydopamine (PDA) as revealed by TEM imaging, which is formed via the oxidative self-polymerization of dopamine. Then the functionalized CNTs (CNT-PDA) were successfully anchored on the skeleton surfaces of sponge, forming a continuous 3D carbon network. The interfacial interaction between modified PU sponge and epoxy (EP) matrix was significantly enhanced due to the covalent linkage of PDA. Improvement in the thermal stability of CNT-PDA/PU3D/EP composites was observed by TG analysis and related to the CNTs anchored on the skeleton of sponge. The tribological properties of pure EP, PU3D/EP and CNT-PDA/PU3D/EP composites were comparatively investigated in terms of different loads and velocities. Results demonstrated that CNT-PDA/PU3D/EP composites exhibited the best tribological performance owing to the strong interfacial interaction and the 3D carbon network structure. In particular, the wear resistance of CNT-PDA/PU3D/EP composites was 6.2 times and 3 times higher than those of pure EP and PU3D/EP composites under the applied load of 1.6 MPa, respectively.

  11. ACID FUNCTIONALIZED SINGLE-WALLED CARBON NANOTUBES ENHANCE CARDIAC ISCHEMIC/REPERFUSIOIN INJURY

    Science.gov (United States)

    Engineered carbon nanotubes are being intensively developed for wide applications. Because of their unique light properties, nanotubes can impose some potentially toxic effects, particularly if they have been modified to express functionally reactive chemical groups on their sur...

  12. Electrochemical detection of p-aminophenol by flexible devices based on multi-wall carbon nanotubes dispersed in electrochemically modified Nafion.

    Science.gov (United States)

    Scandurra, Graziella; Antonella, Arena; Ciofi, Carmine; Saitta, Gaetano; Lanza, Maurizio

    2014-05-21

    A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs) into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs-Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP) in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 µM, with a detection limit of 90 nM and a sensitivity of 7 µA·(µM(-1))·cm(-2).

  13. Electrochemical Detection of p-Aminophenol by Flexible Devices Based on Multi-Wall Carbon Nanotubes Dispersed in Electrochemically Modified Nafion

    Directory of Open Access Journals (Sweden)

    Graziella Scandurra

    2014-05-01

    Full Text Available A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs–Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 µM, with a detection limit of 90 nM and a sensitivity of 7 µA·(µM−1·cm−2.

  14. Determination of 6-Mercaptopurine in Rat Blood by Microdialysis Coupled with High Performance Liquid Chromatography on a Functionalized Multi-wall Carbon Nanotubes Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    LIN Li; QIU Pei-hong; XIE Xia-feng; CAO Xu-ni; JIN Li-tong

    2005-01-01

    A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electrocatalytic oxidation of 6-mercaptopurine(6-MP). The CME can be used as the working electrode in the liquid chromatography for the determination of 6-MP. The peak current of 6-MP is linearly changed with its concentration ranging from 4.0×10-7 to 1.0×10-4 mol/L with the calculated detection limit (S/N= 3) of 2.0×10-7 mol/L. Coupled with microdialysis sampling, the method has been successfully applied to assessing the content of 6-MP in rat blood.

  15. Optimization of bioselective membrane of amperometric enzyme sensor on basis of glucose oxidase using NH2-modified multi-wall carbone nanotubes

    Directory of Open Access Journals (Sweden)

    Korpan Ya. I.

    2010-02-01

    Full Text Available Aim. To investigate a possibility of application of multi-wall carbone nanotubes modified with NH2-groups (MWCNT-NH2 for creation of sensitive elements of the amperometric biosensor based on immobilized oxidoreductases, in particular, glucose oxidase (GOD. To study electrochemical properties of the membranes obtained. Methods. Experiments were carried out with amperometric methods using the ìStat 200 device («DropSens», Spain. The enzymes were immobilised in glutaraldehyde vapour. Results. The method of formation of bioselective matrix based on immobilised GOD with MNP-NH2 on the surface of gold amperometric electrodes was optimised. Optimal working conditions of the biosensor developed were determined. Conclusion. MWCNT integration into a bioselective matrix improves the biosensor analytical characteristics which means: higher signal value, wider linear range of glucose analysis, and possibility of substrate determination in wide range of working potential.

  16. Graphene-multiwall carbon nanotube-gold nanocluster composites modified electrode for the simultaneous determination of ascorbic acid, dopamine, and uric acid.

    Science.gov (United States)

    Liu, Xiaofang; Wei, Shaping; Chen, Shihong; Yuan, Dehua; Zhang, Wen

    2014-08-01

    In this paper, graphene-multiwall carbon nanotube-gold nanocluster (GP-MWCNT-AuNC) composites were synthesized and used as modifier to fabricate a sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electrochemical behavior of the sensor was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The combination of GP, MWCNTs, and AuNCs endowed the electrode with a large surface area, good catalytic activity, and high selectivity and sensitivity. The linear response range for simultaneous detection of AA, DA, and UA at the sensor were 120-1,701, 2-213, and 0.7-88.3 μM, correspondingly, and the detection limits were 40, 0.67, and 0.23 μM (S/N=3), respectively. The proposed method offers a promise for simple, rapid, selective, and cost-effective analysis of small biomolecules.

  17. Multiwalled carbon nanotube modified screen-printed electrodes for the detection of p-aminophenol: Optimisation and application in alkaline phosphatase-based assays

    Energy Technology Data Exchange (ETDEWEB)

    Lamas-Ardisana, Pedro Jose [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain); Queipo, Paula [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo, Asturias (Spain); Fanjul-Bolado, Pablo [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain); Costa-Garcia, Agustin [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain)], E-mail: costa@fq.uniovi.es

    2008-05-12

    Carboxylated multiwalled carbon nanotubes (MWCNT-COOH) were used to modify the working electrode surface of different screen-printed electrodes. The effect of this modification on the electrodic characteristics (double layer capacitance, electroactive area and heterogeneous rate constants for the electron transfer) was evaluated and optimized for the cyclic voltammetric determination of p-aminophenol. The enzymatic hydrolysis of p-aminophenylphosphate was employed for the quantification of alkaline phosphatase, one of the most important label enzymes in immunoassays. Finally, ELISA assays were carried out to quantify pneumolysin using this enzymatic system. Results obtained indicated that low superficial densities of MWCNT-COOH (0.03-0.06 {mu}g mm{sup -2}) yielded the same electrodic improvements but with better analytical properties.

  18. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  19. Process for derivatizing carbon nanotubes with diazonium species and compositions thereof

    Science.gov (United States)

    Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

    2011-01-01

    Methods for the chemical modification of carbon nanotubes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications, and sensor devices. The methods of derivatization include electrochemical induced reactions, thermally induced reactions, and photochemically induced reactions. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes.

  20. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  1. Synthesis of chemically-modified single-walled carbon nanotubes by counter-current ammonia gas injection into the induction thermal plasma process

    Science.gov (United States)

    Shahverdi, Ali

    Pristine single-walled carbon nanotubes (SWCNTs) are poorly dispersible and insoluble in many solvents and need to be chemically modified prior to their use in many applications. This work is focused on the investigation of the synthesis of chemically modified SWCNTs material through an in situ approach. The main objectives of the presented research are: 1) to explore the in situ chemical process during the synthesis of SWCNT and 2) to closely examine the effect of a reactive environment on SWCNTs. Effects of the catalyst type and content on the SWCNTs final product, synthesized by induction thermal plasma (ITP), were studied to replace toxic cobalt (Co) in the feedstock. In this regard, three different catalyst mixtures (i.e. Ni-Y2O3, Ni-Co-Y2O3, and Ni-Mo-Y2O3) were used. Experimental results showed that the catalyst type affects the quality of the SWCNT final product. Similar quality SWCNTs can be produced when the same amount of Co was replaced by Ni. Moreover, the results observed in this experimental work were further explained by thermodynamic calculation results. Thermogravimetry (TG) was used throughout the work to characterize the SWCNTs product. TG was firstly standardized by studying the effects of three main instrumental parameters (temperature ramp, TR, initial mass of the sample, IM, and gas flow rate, FR) on the Tonset and full-width half maximum (FWHM) obtained from TG and derivative TG graphs of carbon black, respectively. Therefore, a two-level factorial statistical design was performed. The statistical analysis showed that the effect of TR, IM, and to a lower extent, FR, is significant on FWHM and insignificant on Tonset. A methodology was then developed based upon the SWCNTs synthesis using the ITP system, through an in situ chemistry approach. Ammonia (NH3) was selected and counter-currently injected into the ITP reactor at three different flow rates and by four different nozzle designs. Numerical simulation indicated a better mixing of NH3 in

  2. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHU Ying; LI WenXin

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained,lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However,experimental information obtained thus far on CNTs' cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTa in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs' cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  3. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained, lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However, experimental information obtained thus far on CNTs’ cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTs in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs’ cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  4. pH-controlled doxorubicin anticancer loading and release from carbon nanotube noncovalently modified by chitosan: MD simulations.

    Science.gov (United States)

    Rungnim, Chompoonut; Rungrotmongkol, Thanyada; Poo-Arporn, Rungtiva P

    2016-11-01

    In the present study, we describe here the pH condition activating doxorubicin (DOX) anticancer drugs loading and release over single-wall carbon nanotube (SWNT) non-covalently wrapped with chitosan (CS). The possibility of drug displacement on DOX/CS/SWNT nanocarrier was investigated using molecular dynamics simulations. The drug loading and release were monitored via displacement analysis and binding energy calculations. The simulated results clearly showed that the drugs well interacted with the CS/SWNT at physiological pH (pH 7.4), where CS was in the deprotonated form. Contrastingly, in weakly acidic environments (pH 5.0-6.5) which is a pH characteristics of certain cancer environments, the protonated CS became loosen wrapped around the SWNT and triggered drugs release as a result of charge-charge repulsion between CS and drug molecules. The obtained data fulfil the understanding at atomic level of drug loading and release controlled by pH-sensitive polymer, which might be useful for further cancer therapy researches.

  5. Enhanced Electrical Conductivity in Extruded Single-Wall Carbon Nanotube Wires from Modified Coagulation Parameters and Mechanical Processing.

    Science.gov (United States)

    Bucossi, Andrew R; Cress, Cory D; Schauerman, Christopher M; Rossi, Jamie E; Puchades, Ivan; Landi, Brian J

    2015-12-16

    Single-wall carbon nanotubes (SWCNTs) synthesized via laser vaporization have been dispersed using chlorosulfonic acid (CSA) and extruded under varying coagulation conditions to fabricate multifunctional wires. The use of high purity SWCNT material based upon established purification methods yields wires with highly aligned nanoscale morphology and an over 4× improvement in electrical conductivity over as-produced SWCNT material. A series of eight liquids have been evaluated for use as a coagulant bath, and each coagulant yielded unique wire morphology based on its interaction with the SWCNT-CSA dispersion. In particular, dimethylacetamide as a coagulant bath is shown to fabricate highly uniform SWCNT wires, and acetone coagulant baths result in the highest specific conductivity and tensile strength. A 2× improvement in specific conductivity has been measured for SWCNT wires following tensioning induced both during extrusion via increased coagulant bath depth and during solvent evaporation via mechanical strain, over that of as-extruded wires from shallower coagulant baths. Overall, combination of the optimized coagulation parameters has yielded acid-doped wires with the highest reported room temperature electrical conductivities to date of 4.1-5.0 MS/m and tensile strengths of 210-250 MPa. Such improvements in bulk electrical conductivity can impact the adoption of metal-free, multifunctional SWCNT materials for advanced cabling architectures.

  6. p-toluene sulfonic acid doped polyaniline carbon nanotube composites: synthesis via different routes and modified properties

    Directory of Open Access Journals (Sweden)

    ASHOK K. SHARMA

    2013-04-01

    Full Text Available Composites of polyaniline and carbon nanotube (CNT were prepared by in-situ chemical polymerization method using various aniline concentrations in the initial polymerization solution with p-toluene sulfonic acid (PTS as secondary dopant and mechanical mixing of the PANI and CNT using different weight ratios of PANI and CNTs. The structural characterizations of the composites were done by Fourier transform infrared (FTIR and Ultra violet visible spectroscopy (UV-Visible. Scanning electron microscopy (SEM was used to characterize the surface morphology of the composites. It was found that the composites prepared by in-situ chemical polymerization had smoother surface morphology in comparison to the composites obtained by mechanical mixing. The capacitive studies reveal that the in-situ composite has synergistic effect and the specific capacitance of the composite calculated from cyclic voltammogram (CV was 385.1 F/g. Thermal studies indicate that the composites are stable as compared to PANI alone showing that the CNT contributes towards thermal stability in the PANI-CNT composites.

  7. Highly Selective and Sensitive Detection of Acetylcholine Using Receptor-Modified Single-Walled Carbon Nanotube Sensors

    Science.gov (United States)

    Xu, Shihong; Kim, Byeongju; Song, Hyun Seok; Jin, Hye Jun; Park, Eun Jin; Lee, Sang Hun; Lee, Byung Yang; Park, Tai Hyun; Hong, Seunghun

    2015-03-01

    Acetylcholine (ACh) is a neurotransmitter in a human central nervous system and is related to various neural functions such as memory, learning and muscle contractions. Dysfunctional ACh regulations in a brain can induce several neuropsychiatric diseases such as Alzheimer's disease, Parkinson's disease and myasthenia gravis. In researching such diseases, it is important to measure the concentration of ACh in the extracellular fluid of the brain. Herein, we developed a highly sensitive and selective ACh sensor based on single-walled carbon nanotube-field effect transistors (swCNT-FETs). In our work, M1 mAChR protein, an ACh receptor, was expressed in E.coli and coated on swCNT-FETs with lipid membranes. Here, the binding of ACh onto the receptors could be detected by monitoring the change of electrical currents in the underlying swCNT-FETs, allowing the real-time detection of ACh at a 100 pM concentration. Furthermore, our sensor could selectively detect ACh from other neurotransmitters. This is the first report of the real-time sensing of ACh utilizing specific binding between the ACh and M1 mAChR, and it may lead to breakthroughs in various biomedical applications such as drug screening and disease diagnosis.

  8. Effect of copper ion on adsorption of chlorinated phenols and 1-naphthylamine to surface-modified carbon nanotubes.

    Science.gov (United States)

    Wang, Fang; Zhu, Dongqiang; Chen, Wei

    2012-01-01

    Understanding the adsorptive interactions between organic contaminants and carbon nanotubes (CNTs) is critical to both environmental applications and risk management of CNTs. The objective of the present study was to understand how transitional metal ions with strong complexing capabilities might affect the adsorption of hydroxyl- and amino-substituted aromatics to surface O-functionality-rich single-walled CNTs (O-SWNT) and N-functionality-rich single-walled CNTs (N-SWNT). Adsorption of 2,4-dichlorophenol, pentachlorophenol, and 1-naphthylamine to O-SWNT and N-SWNT can be significantly enhanced in the presence of Cu(II) (50 mg/L), whereas adsorption of 1,2-dichlorobenzene is essentially unaffected. The most likely mechanism for the Cu-enhanced adsorption is that Cu(II) serves as a bridging agent between organic solutes and the functional groups on CNT surfaces. For the adsorption of 1-naphthylamine to N-SWNT, an additional mechanism might be possible; that is, the complexation of Cu(II) with the N-functional groups of N-SWNT can change these groups from strong Lewis bases to Lewis acids and thereby significantly enhance adsorption via the mechanism of Lewis acid-base interactions. In addition, adsorption of Cu(II) can be significantly enhanced by the adsorption of organic cosolutes.

  9. Synergistic Enhancement of Antitumor Efficacy by PEGylated Multi-walled Carbon Nanotubes Modified with Cell-Penetrating Peptide TAT

    Science.gov (United States)

    Hu, Shanshan; Wang, Tong; Pei, Xibo; Cai, He; Chen, Junyu; Zhang, Xin; Wan, Qianbing; Wang, Jian

    2016-10-01

    In the present study, a cell-penetrating peptide, the transactivating transcriptional factor (TAT) domain from HIV, was linked to PEGylated multi-walled carbon nanotubes (MWCNTs) to develop a highly effective antitumor drug delivery system. FITC was conjugated on MWCNTs-polyethylene glycol (PEG) and MWCNTs-PEG-TAT to provide fluorescence signal for tracing the cellular uptake of the nanocarrier. After loaded with an anticancer agent, doxorubicin (DOX) via π - π stacking interaction, the physicochemical characteristics, release profile and biological evaluation of the obtained nano-sized drug carrier were investigated. The DOX loaded MWCNTs-PEG and MWCNTs-PEG-TAT drug carriers both displayed appropriate particle size, excellent stability, high drug loading, and pH-dependent drug release profile. Nevertheless, compared with DOX-MWCNTs-PEG, DOX-MWCNTs-PEG-TAT showed improved cell internalization, intracellular distribution and potentiated anticancer efficacy due to the TAT-mediated membrane translocation, endosomal escape and nuclear targeting. Furthermore, the therapeutic efficacy of DOX was not compromised after being conjugated with MWCNTs-PEG-TAT and the proposed nanocarrier was also confirmed to have a good biocompatibility. In conclusion, our results suggested that the unique combination of TAT and MWCNTs as a multifunctional drug delivery system might be a powerful tool for improved anticancer drug development.

  10. Electrocatalytic oxidation of methanol on carbon-nanotubes/graphite electrode modified with platinum and molybdenum oxide nanoparticles

    Institute of Scientific and Technical Information of China (English)

    GAN Yong-ping; HUANG Hui; ZHANG Wen-kui

    2007-01-01

    Electrochemical codeposition and electrocatalytic properties of platinum and molybdenum oxide nanoparticles (Pt-MoOx) on carbon-nanotubes/graphite electrode for methanol oxidation were investigated. The micrograph and elemental composition of the resulting Pt-MoOx/CNTs/graphite electrode were characterized by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS). The results show that the Pt-MoOx particles with the average size of about 50 nm are highly dispersed on the CNTs surface. The Pt-MoOx/CNTs/graphite electrode delivers excellent electrocatalytic properties for methanol oxidation. The highest mass activity(Am) reaches 264.8 A/g at the loading mass of 159.3 (g/cm2. This may be attributed to the small particle size and high dispersion of Pt-MoOx catalysts deposited on the CNTs surface. The kinetic analysis from electrochemical impedance spectroscopy(EIS) reveals that the existed MoOx phase can improve the chemisorptive and catalytic properties for methanol oxidation.

  11. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2015-01-01

    Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

  12. Measurement of the thermal conductivity of a water-based single-wall carbon nanotube colloidal suspension with a modified 3- {omega} method

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Tae Y [Department of Mechanical and Energy Engineering, University of North Texas, Denton, TX, 76203-1098 (United States); Maneshian, Mohammad H [Department of Materials Science and Engineering, University of North Texas, Denton, TX, 76203-5017 (United States); Kang, Boseon [School of Mechanical Systems Engineering, Chonnam National University, 500-757, Gwangju (Korea, Republic of); Chang, Won S; Han, Chang S [Department of Nanomechanical Systems, Korea Institute of Machinery and Materials, Daejeon, 305-343 (Korea, Republic of); Poulikakos, Dimos, E-mail: choi@egw.unt.ed [Department of Mechanical and Process Engineering, Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, CH-8092 (Switzerland)

    2009-08-05

    A modified 3-{omega} method applied to a suspended platinum microwire was employed to measure the thermal conductivity and convective heat transfer coefficient of a water-based single-walled carbon nanotube (CNT) solution (metallic single-wall nanotubes with 1.33 nm diameter and 1.14 wt% concentration), and an expression for calculating the convective heat transfer coefficient in such a free convective fluid was introduced. The measurement technique was validated for three model systems including vacuum, air and deionized water. It is found that there is excellent agreement between these three model systems with theoretical predictions. In addition, the frequency dependence on the third harmonic response measured in deionized water reveals the existence of a very low working frequency below 60 mHz. The thermal conductivity and convective heat transfer coefficient of the nanofluid (water-based single-wall CNT solution) were determined to be 0.73 {+-} 0.013 W m{sup -1} K{sup -1} and 14 900 {+-} 260 W m{sup -2} K{sup -1}, respectively, which correspond to an enhancement of 19.4% in thermal conductivity and 18.9% in convective heat transfer as compared to water.

  13. Measurement of the thermal conductivity of a water-based single-wall carbon nanotube colloidal suspension with a modified 3- omega method.

    Science.gov (United States)

    Choi, Tae Y; Maneshian, Mohammad H; Kang, Boseon; Chang, Won S; Han, Chang S; Poulikakos, Dimos

    2009-08-05

    A modified 3-omega method applied to a suspended platinum microwire was employed to measure the thermal conductivity and convective heat transfer coefficient of a water-based single-walled carbon nanotube (CNT) solution (metallic single-wall nanotubes with 1.33 nm diameter and 1.14 wt% concentration), and an expression for calculating the convective heat transfer coefficient in such a free convective fluid was introduced. The measurement technique was validated for three model systems including vacuum, air and deionized water. It is found that there is excellent agreement between these three model systems with theoretical predictions. In addition, the frequency dependence on the third harmonic response measured in deionized water reveals the existence of a very low working frequency below 60 mHz. The thermal conductivity and convective heat transfer coefficient of the nanofluid (water-based single-wall CNT solution) were determined to be 0.73 +/- 0.013 W m(-1) K(-1) and 14 900 +/- 260 W m(-2) K(-1), respectively, which correspond to an enhancement of 19.4% in thermal conductivity and 18.9% in convective heat transfer as compared to water.

  14. Hybrid Composite of Polyaniline Containing Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Carbon nanotube-polyaniline hybrid material was synthesized by emulsion polymerization in-situ. The morphology of hybrid material was studied by TEM and X-ray diffraction. The conductivity of nanocomposite increases with the increasing of carbon nanotube content because of the new conductivity passageways formed by carbon nanotubes.

  15. Synthesis and Application of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Qun Zeng; Zhenhua Li; Yuhong Zhou

    2006-01-01

    Owing to the unique structure, the superior physical and chemical properties, the super strong mechanical performances, and so on, carbon nanotubes have attracted the attention of researchers all over the world. In this article, the basic properties and the main production processes of carbon nanotubes are introduced in brief, and the progress of applied research for carbon nanotubes is reviewed.

  16. Kinetic and analytical comparison of horseradish peroxidase on bare- and redox-modified single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Palangsuntikul, Rungtiva [Biological Engineering Program, King Mongkut' s University of Technology Thonburi, Bangmod Campus, Pracha-utit Rd., Bangkok 10140 (Thailand); Somasundrum, Mithran, E-mail: mithran.somasundrum@gmail.co [Biochemical Engineering and Pilot Plant Research and Development Unit, National Center for Genetic Engineering and Biotechnology, Phahonyothin Rd., Prathumthani 12120 (Thailand); Surareungchai, Werasak, E-mail: werasak.sur@kmutt.ac.t [Biological Engineering Program, King Mongkut' s University of Technology Thonburi, Bangmod Campus, Pracha-utit Rd., Bangkok 10140 (Thailand); School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, Bangkhuntien Campus, Bangkhuntien-Chaitalay Rd., Bangkok 10150 (Thailand)

    2010-12-15

    Single-walled carbon nanotubes (SWNTs) were coated first with methylene blue (MB) by noncovalent adsorption and then by horseradish peroxidase (HRP) by cross-linking with glutaraldehyde. The MB-SWNT/HRP composites formed stable films on glassy carbon electrodes. MB was probably present with a coverage of a monolayer or less. The MB voltammetry was consistent with fast electron transfer to a surface-confined species. The presence of HRP did not significantly affect the MB electrochemistry. MB could mediate electron transfer from HRP in the presence of H{sub 2}O{sub 2}. Cyclic voltammograms of this process were used to determine the rate constants for the reactions of the native ferriperoxidase with H{sub 2}O{sub 2} and of the oxyferryl Compound II with the reduced form of MB. For comparison purposes, the rate constant for the direct electrode reduction of the HRP oxyferryl {pi}-cation radical Compound I was determined in MB-free SWNTs. The results indicate a considerably faster regeneration rate for native ferriperoxidase by the mediated reaction than by direct electrochemistry. Using the MB-SWNT/HRP composites, H{sub 2}O{sub 2} could be calibrated by amperometry at -0.3 V vs. SCE. The optimized response (at pH 7.0) had a sensitivity of 661.0 {mu}A mM{sup -1} cm{sup -2} and a limit of detection (3 x S/N) of 0.1 {mu}M.

  17. Simultaneous determination of endocrine disrupting compounds bisphenol F and bisphenol AF using carboxyl functionalized multi-walled carbon nanotubes modified electrode.

    Science.gov (United States)

    Yang, Jichun; Wang, Xin; Zhang, Danfeng; Wang, Lingling; Li, Qi; Zhang, Lei

    2014-12-01

    A novel, simple and selective electrochemical method was developed for simultaneous determination of bisphenol F (BPF) and bisphenol AF (BPAF) in aqueous media (phosphate buffer solution, pH 6.0) on carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-COOH/GCE) using differential pulse voltammetry (DPV). In DPV, MWCNT-COOH/GCE could separate the oxidation peak potentials of BPF and BPAF present in the same solution though, at the bare GCE, the peak potentials were indistinguishable. The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the two analytes. The peak current in DPV of BPF and BPAF increased linearly with their concentration in the ranges of 0.6-1.6 mmol/L BPF and 0.6-1.6 mmol/L BPAF. The detection limits were 0.1243 mmol/L and 0.1742 mmol/L (S/N=3) correspondingly. The modified electrode was successfully used to simultaneously determine BPF and BPAF in real samples.

  18. The Cu-MOF-199/single-walled carbon nanotubes modified electrode for simultaneous determination of hydroquinone and catechol with extended linear ranges and lower detection limits.

    Science.gov (United States)

    Zhou, Jian; Li, Xi; Yang, Linlin; Yan, Songlin; Wang, Mengmeng; Cheng, Dan; Chen, Qi; Dong, Yulin; Liu, Peng; Cai, Weiquan; Zhang, Chaocan

    2015-10-29

    A novel electrochemical sensor based on Cu-MOF-199 [Cu-MOF-199 = Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylicacid)] and SWCNTs (single-walled carbon nanotubes) was fabricated for the simultaneous determination of hydroquinone (HQ) and catechol (CT). The modification procedure was carried out through casting SWCNTs on the bare glassy carbon electrode (GCE) and followed by the electrodeposition of Cu-MOF-199 on the SWCNTs modified electrode. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were performed to characterize the electrochemical performance and surface characteristics of the as-prepared sensor. The composite electrode exhibited an excellent electrocatalytic activity with increased electrochemical signals towards the oxidation of HQ and CT, owing to the synergistic effect of SWCNTs and Cu-MOF-199. Under the optimized condition, the linear response range were from 0.1 to 1453 μmol L(-1) (RHQ = 0.9999) for HQ and 0.1-1150 μmol L(-1) (RCT = 0.9990) for CT. The detection limits for HQ and CT were as low as 0.08 and 0.1 μmol L(-1), respectively. Moreover, the modified electrode presented the good reproducibility and the excellent anti-interference performance. The analytical performance of the developed sensor for the simultaneous detection of HQ and CT had been evaluated in practical samples with satisfying results.

  19. CTAB functionalized graphene oxide/multiwalled carbon nanotube composite modified electrode for the simultaneous determination of ascorbic acid, dopamine, uric acid and nitrite.

    Science.gov (United States)

    Yang, Yu Jun; Li, Weikun

    2014-06-15

    We have developed hexadecyl trimethyl ammonium bromide (CTAB) functionalized graphene oxide (GO)/multiwalled carbon nanotubes (MWNTs) modified glassy carbon electrode (CTAB-GO/MWNT) as a novel system for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO2(-)). The combination of graphene oxide and MWNTs endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO2(-) were obtained over the range of 5.0-300 μM, 5.0-500 μM, 3.0-60 μM and 5.0-800 μM with detection limits of 1.0 μM, 1.5 μM, 1.0 μM and 1.5 μM, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO2(-) in urine samples by using standard adding method with satisfactory results.

  20. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Shuguang; LI Yanhui

    2004-01-01

    The properties and applications of CNT have been studied extensively since Iijima discovered them in 1991[1,2]. They have exceptional mechanical properties and unique electrical property, highly chemical stability and large specific surface area. Thus far, they have widely potential applications in many fields. They can be used as reinforcing materials in composites[3], field emissions[4], hydrogen storage[5], nanoelectronic components[6], catalyst supports[7], adsorption material and so on. However, the study on the potential application of CNT, environmental protection field in particular, was hardly begun.Long[8] et al. reported that CNT had a significantly higher dioxin removal efficiency than that of activated carbon. The Langmuir adsorption constant is 2.7 × 1052, 1.3 × 1018 respectively. The results indicated that CNT is potential candidate for the removal of micro-organic pollutants. However, the reports on the CNT used as fluoride and heavy metal adsorbent are seldom.In this paper, A novel material, alumina supported on carbon nanotubes (Al2O3/CNT), was prepared from carbon nanotubes and Al(NO3)3. X-ray diffraction (XRD) spectra demonstrate that alumina is amorphous, and scanning electron microscope (SEM) images show that CNT and alumina are homogeneously mixed. Furthermore, the fluoride adsorption behavior on the surface of Al2O3/CNT has been investigated and compared with other adsorbents. The results indicate that Al2O3/CNT has a high adsorption capacity, with a saturation adsorption capacity of 39.4 mg/g. It is also found that the adsorption capacity of Al2O3/CNT is 3.0~4.5 times that of γ-Al2O3while almost equal to that of IRA-410 polymeric resin at 25 ℃. The adsorption isotherms of fluoride on Al2O3/CNT is fit the Freundlich equation well, optimal pH ranging from 5.0 to 9.0.Also in this paper, a novel material, modified carbon nanotubes (CNT), was prepared from carbon nanotubes and HNO3 under boiling condition. Infrared spectroscopy (IR

  1. Hydrodynamic properties of carbon nanotubes.

    Science.gov (United States)

    Walther, J H; Werder, T; Jaffe, R L; Koumoutsakos, P

    2004-06-01

    We study water flowing past an array of single walled carbon nanotubes using nonequilibrium molecular dynamics simulations. For carbon nanotubes mounted with a tube spacing of 16.4 x 16.4 nm and diameters of 1.25 and 2.50 nm, respectively, we find drag coefficients in reasonable agreement with the macroscopic, Stokes-Oseen solution. The slip length is -0.11 nm for the 1.25 nm carbon nanotube, and 0.49 for the 2.50 nm tube for a flow speed of 50 m/s, respectively, and 0.28 nm for the 2.50 nm tube at 200 m/s. A slanted flow configuration with a stream- and spanwise velocity component of 100 ms(-1) recovers the two-dimensional results, but exhibits a significant 88 nm slip along the axis of the tube. These results indicate that slip depends on the particular flow configuration.

  2. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes.

    Science.gov (United States)

    Sun, Wei; Cao, Lili; Deng, Ying; Gong, Shixing; Shi, Fan; Li, Gaonan; Sun, Zhenfan

    2013-06-05

    A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (ks) as 0.97 s(-1). The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L(-1) with a detection limit of 0.0153 mmol L(-1) (3σ), H2O2 in the concentration range from 0.1 to 516.0 mmol L(-1) with a detection limit of 34.9 nmol/L (3σ) and NaNO2 in the concentration range from 0.5 to 650.0 mmol L(-1) with a detection limit of 0.282 μmol L(-1) (3σ). So the proposed electrode had the potential application in the third-generation electrochemical biosensors without mediator.

  3. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.;

    2015-01-01

    by recent advances in theory. As well as the well-understood overall picture, we also state clearly open questions for the field. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  4. Interaction of microwaves with carbon nanotubes to facilitate modification

    Science.gov (United States)

    Tour, James M. (Inventor); Dyke, Christopher A. (Inventor); Stephenson, Jason J. (Inventor); Yakobson, Boris I. (Inventor)

    2011-01-01

    The present invention is directed toward methods of crosslinking carbon nanotubes to each other using microwave radiation, articles of manufacture produced by such methods, compositions produced by such methods, and applications for such compositions and articles of manufacture. The present invention is also directed toward methods of radiatively modifying composites and/or blends comprising carbon nanotubes with microwaves, and to the compositions produced by such methods. In some embodiments, the modification comprises a crosslinking process, wherein the carbon nanotubes serve as a conduit for thermally and photolytically crosslinking the host matrix with microwave radiation.

  5. Carbon nanotube-polymer composite actuators

    Science.gov (United States)

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  6. Functionalization of vertically aligned carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Eloise Van Hooijdonk

    2013-02-01

    Full Text Available This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs. The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs.

  7. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.

    2015-01-01

    modifies their transport behaviour. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  8. Deposition of new thia-containing Schiff-base iron (III) complexes onto carbon nanotube-modified glassy carbon electrodes as a biosensor for electrooxidation and determination of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Saghatforoush, Lotfali [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Hasanzadeh, Mohammad, E-mail: mhmmd_hasanzadeh@yahoo.co [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology (KNTU), Tehran (Iran, Islamic Republic of); Shadjou, Nasrin [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology (KNTU), Tehran (Iran, Islamic Republic of); Khalilzadeh, Balal [Department of Analytical Chemistry, Faculty of Science, Arak University, Arak (Iran, Islamic Republic of)

    2011-01-01

    Multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate an Fe (III)-Schiff base complex as an electron-transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on filter paper supporting the carbon nanotubes. Second, the electrode surface was modified by casting 100 {mu}L of an Fe (III)-complex solution (0.01 M in ACN). The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and nearly reversible reductive oxidation redox systems with surface confined characteristics. Combinations of unique electronic and electrocatalytic properties of MWCNTs and Fe (III)-Schiff base complexes resulted in a remarkable synergistic augmentation of the response. The electrochemical behavior and stability of the modified electrode in aqueous solutions at pH 1-9 were characterized by cyclic voltammetry. The apparent electron transfer rate constant (K{sub s}) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7 s{sup -1} and 0.55, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of amino acids at an unusually positive potential in acidic solution. They also displayed inherent stability at a wide pH range, fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of amino acids that decreased the effect of interferences in analysis. The linear concentration range, limits of detection (LOD), limits of quantization (LOQ) and relative standard deviation of the proposed sensor for the amino acid detection were 1-55,000, 1.10-13.70, 2.79-27.14 and 1.30-5.11, respectively.

  9. Electrochemical determination of sulphide at multi-walled carbon nanotubes-dihexadecyl hydrogen phosphate composite film modified electrodes based on in situ synthesis of methylene blue

    Institute of Scientific and Technical Information of China (English)

    An Min Xiang; Li Zhou; Cheng Guo Hu; Sheng Shui Hu

    2008-01-01

    A novel electrochemical method for the determination of sulphide at a multi-walled carbon nanotube-dihexadecyl hydrogenphosphate composite film coated glassy carbon electrode (MWNTs-DHP/GCE) based on in situ synthesis of methylene blue (MB)was established.

  10. Carbon nanotube--poly(3-octylthiophene) composite photovoltaic cells.

    Science.gov (United States)

    Carroll, David L; Czerw, Richard; Harrison, Benjamin

    2006-07-01

    The effects of varying nanotube loading/concentration in carbon nanotube-poly(3-octylthiophene) blends used as thin film photovoltaic cells, have been studied. The network of single walled nanotubes clearly aids in exciton separation and modifies carrier mobility within the active layer as suggested by a bulk heterojunction model. Further, modifications to the metal-polymer interface occur with the addition of nanotubes leading to variations in the observed VOC of the photovoltaic cells. Finally, the "nanocomposite" devices exhibit significant enhancements to external power conversion efficiencies, with the overall efficiency strongly dependent on device design parameters such as the addition of buffer layers.

  11. The Cu-MOF-199/single-walled carbon nanotubes modified electrode for simultaneous determination of hydroquinone and catechol with extended linear ranges and lower detection limits

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jian [School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (China); Li, Xi, E-mail: chemlixi@whut.edu.cn [School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (China); Yang, Linlin; Yan, Songlin; Wang, Mengmeng; Cheng, Dan; Chen, Qi; Dong, Yulin; Liu, Peng; Cai, Weiquan [School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Chaocan, E-mail: polymers@whut.edu.cn [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2015-10-29

    A novel electrochemical sensor based on Cu-MOF-199 [Cu-MOF-199 = Cu{sub 3}(BTC){sub 2} (BTC = 1,3,5-benzenetricarboxylicacid)] and SWCNTs (single-walled carbon nanotubes) was fabricated for the simultaneous determination of hydroquinone (HQ) and catechol (CT). The modification procedure was carried out through casting SWCNTs on the bare glassy carbon electrode (GCE) and followed by the electrodeposition of Cu-MOF-199 on the SWCNTs modified electrode. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were performed to characterize the electrochemical performance and surface characteristics of the as-prepared sensor. The composite electrode exhibited an excellent electrocatalytic activity with increased electrochemical signals towards the oxidation of HQ and CT, owing to the synergistic effect of SWCNTs and Cu-MOF-199. Under the optimized condition, the linear response range were from 0.1 to 1453 μmol L{sup −1} (R{sub HQ} = 0.9999) for HQ and 0.1–1150 μmol L{sup −1} (R{sub CT} = 0.9990) for CT. The detection limits for HQ and CT were as low as 0.08 and 0.1 μmol L{sup −1}, respectively. Moreover, the modified electrode presented the good reproducibility and the excellent anti-interference performance. The analytical performance of the developed sensor for the simultaneous detection of HQ and CT had been evaluated in practical samples with satisfying results. - Highlights: • Cu-MOF-199/SWCNTs/GCE was facilely fabricated by the electrodeposition on SWCNTs/GCE. • An electrochemical sensor for detecting HQ and CT was constructed based on this modified electrode. • The proposed electrochemical sensor showed an extended linear range and lower detection limits. • The proposed electrochemical sensor had an excellent stability and reproducibility.

  12. Effects of fullerene (C60), multi-wall carbon nanotubes (MWCNT), single wall carbon nanotubes (SWCNT) and hydroxyl and carboxyl modified single wall carbon nanotubes on riverine microbial communities.

    Science.gov (United States)

    Lawrence, J R; Waiser, M J; Swerhone, G D W; Roy, J; Tumber, V; Paule, A; Hitchcock, A P; Dynes, J J; Korber, D R

    2016-05-01

    Commercial production of nanoparticles (NP) has created a need for research to support regulation of nanotechnology. In the current study, microbial biofilm communities were developed in rotating annular reactors during continuous exposure to 500 μg L(-1) of each nanomaterial and subjected to multimetric analyses. Scanning transmission X-ray spectromicroscopy (STXM) was used to detect and estimate the presence of the carbon nanomaterials in the biofilm communities. Microscopy observations indicated that the communities were visibly different in appearance with changes in abundance of filamentous cyanobacteria in particular. Microscale analyses indicated that fullerene (C60) did not significantly (p < 0.05) impact algal, cyanobacterial or bacterial biomass. In contrast, MWCNT exposure resulted in a significant decline in algal and bacteria biomass. Interestingly, the presence of SWCNT products increased algal biomass, significantly in the case of SWCNT-COOH (p < 0.05) but had no significant impact on cyanobacterial or bacterial biomass. Thymidine incorporation indicated that bacterial production was significantly reduced (p < 0.05) by all nanomaterials with the exception of fullerene. Biolog assessment of carbon utilization revealed few significant effects with the exception of the utilization of carboxylic acids. PCA and ANOSIM analyses of denaturing gradient gel electrophoresis (DGGE) results indicated that the bacterial communities exposed to fullerene were not different from the control, the MWCNT and SWNT-OH differed from the control but not each other, whereas the SWCNT and SWCNT-COOH both differed from all other treatments and were significantly different from the control (p < 0.05). Fluorescent lectin binding analyses also indicated significant (p < 0.05) changes in the nature and quantities of exopolymer consistent with changes in microbial community structure during exposure to all nanomaterials. Enumeration of protozoan grazers

  13. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Laird, E.A.; Kuemmeth, F.; Steele, G.A.; Grove-Rasmussen, K.; Nygard, J.; Flensberg, K.; Kouwenhoven, L.P.

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This revie

  14. Single-Walled-Carbon-Nanotube-Modified Pyrolytic Graphite Electrode Used as a Simple Sensor for the Determination of Salbutamol in Urine

    Directory of Open Access Journals (Sweden)

    Rajendra N. Goyal

    2011-01-01

    Full Text Available A fast and sensitive voltammetric method has been proposed for the determination of salbutamol at single-walled-carbon-nanotube-modified edge-plane pyrolytic graphite electrode (SWNT/EPPGE in human urine. The electrochemical response of salbutamol was determined by square wave voltammetry (SWV in phosphate buffer solution (PBS at physiological pH 7.2. The modified electrode showed improved voltammetric response towards the oxidation of salbutamol, and a well-defined anodic peak was observed at ~600 mV with enhanced peak current in comparison to the bare electrode. Linear calibration plot using SWNT/EPPGE was obtained in the concentration range of 50 to 2500 ngml-1 with sensitivity and detection limit of 2.15 nA/ngml-1 and 4.31 ngml-1, respectively. The developed method has been successfully applied for the determination of salbutamol in commercial preparations and human body fluids. Fast analysis of salbutamol in human urine makes the proposed method of great interest for doping control purposes at the site of competitive games.

  15. Electroanalysis and simultaneous determination of 6-thioguanine in the presence of uric acid and folic acid using a modified carbon nanotube paste electrode.

    Science.gov (United States)

    Beitollahi, Hadi; Raoof, Jahan-Bakhsh; Hosseinzadeh, Rahman

    2011-01-01

    The present work describes the preparation and characterization of a carbon nanotube paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one (2,7-BF). This electrode showed an efficient catalytic activity for the electro-oxidation of 6-thioguanine (6-TG), which leads to lowering 6-TG overpotential by more than 610 mV. Also, the values of catalytic rate constant (k = 2.7 × 10(3) mol(-1) L s(-1)), and diffusion coefficient (D = 2.7 × 10(-5) cm(2) s) were calculated. In 0.1 M phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of 6-TG, one is 0.06 to 10.0 µmol L(-1) and the other is 10.0 to 160.0 µmol L(-1). The detection limit (3σ) obtained by differential pulse voltammetry (DPV) was 22.0 nmol L(-1). DPV was used for simultaneous determination of 6-TG, uric acid (UA) and folic acid (FA) at the modified electrode, and for quantification of 6-TG, UA and FA in some real samples by the standard addition method.

  16. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand2013@gmail.com; Mohammadi-Behzad, Leila

    2015-12-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk.

  17. Electrocatalytic detection of dopamine in the presence of ascorbic acid and uric acid using single-walled carbon nanotubes modified electrode.

    Science.gov (United States)

    Li, Yaya; Du, Jie; Yang, Jiandong; Liu, Dong; Lu, Xiaoquan

    2012-09-01

    Single-walled carbon nanotubes (SWCNTs) fabricated by sodium dodecyl sulfate (SDS) (f-SWCNTs) modified glassy carbon electrodes (f-SWCNTs/GCE) for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The f-SWCNTs/GCE displayed very good electrochemical catalytic activities with respect to GCE. The oxidation over-potentials of DA and UA decreased dramatically, and their oxidation peak currents increased significantly at f-SWCNTs/GCE compared to those obtained at the bare GCE. Simultaneously, the oxidation peak currents of AA decreased accordingly. The f-SWCNTs/GCE not only divide the overlapping voltammetric responses of them into individual voltammetric peaks, but also totally eliminate the interference from AA and distinguish DA from UA. The catalytic peak currents obtained from square-wave voltammetry increased linearly with increasing DA concentrations in the range of 5.0×10(-6) to 1.0×10(-4)M with a detection limit of 2.0×10(-8)M (S/N=3). The method was also successfully applied for determination of DA and showed good recovery in some biological fluids.

  18. Surface-enhanced oxidation and detection of Sunset Yellow and Tartrazine using multi-walled carbon nanotubes film-modified electrode.

    Science.gov (United States)

    Zhang, Weikang; Liu, Tao; Zheng, Xiaojiang; Huang, Wensheng; Wan, Chidan

    2009-11-01

    The insoluble multi-walled carbon nanotubes (MWNT) was successfully dispersed into water in the presence of hydrophobic surfactant. After that, MWNT film-coated glassy carbon electrode (GCE) was achieved via dip-coating and evaporating water. Owing to huge surface area, high sorption capacity and subtle electronic properties, MWNT film exhibits highly efficient accumulation efficiency as well as considerable surface enhancement effects to Sunset Yellow and Tartrazine. As a result, the oxidation peak currents of Sunset Yellow and Tartrazine remarkably increase at the MWNT film-modified GCE. Based on this, a novel electrochemical method was developed for the simultaneous determination of Sunset Yellow and Tartrazine. The limits of detection are 10.0 ng mL(-1) (2.2 x 10(-8)mol L(-1)) and 0.1 microg mL(-1) (1.88 x 10(-7)mol L(-1)) for Sunset Yellow and Tartrazine. Finally, the proposed method was successfully used to detect Sunset Yellow and Tartrazine in soft drinks.

  19. Developing Carbon Nanotube Standards at NASA

    Science.gov (United States)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

  20. Peel test of spinnable carbon nanotube webs

    Science.gov (United States)

    Khandoker, Noman; Hawkins, Stephen C.; Ibrahim, Raafat; Huynh, Chi P.

    2014-06-01

    This paper presents results of peel tests with spinnable carbon nanotube webs. Peel tests were performed to study the effect of orientation angles on interface energies between nanotubes. In absence of any binding agent the interface energy represents the Van Der Waals energies between the interacting nanotubes. Therefore, the effect of the orientations on Van Der Waals energies between carbon nanotubes is obtained through the peel test. It is shown that the energy for crossed nanotubes at 90° angle is lower than the energy for parallel nanotubes at 0° angle. This experimental observation was validated by hypothetical theoretical calculations.

  1. From carbon nanotubes to carbon atomic chains

    Science.gov (United States)

    Casillas García, Gilberto; Zhang, Weijia; José-Yacamán, Miguel

    2010-10-01

    Carbyne is a linear allotrope of carbon. It is formed by a linear arrangement of carbon atoms with sp-hybridization. We present a reliable and reproducible experiment to obtain these carbon atomic chains using few-layer-graphene (FLG) sheets and a HRTEM. First the FLG sheets were synthesized from worm-like exfoliated graphite and then drop-casted on a lacey-carbon copper grid. Once in the TEM, two holes are opened near each other in a FLG sheet by focusing the electron beam into a small spot. Due to the radiation, the carbon atoms rearrange themselves between the two holes and form carbon fibers. The beam is concentrated on the carbon fibers in order excite the atoms and induce a tension until multi wall carbon nanotube (MWCNT) is formed. As the radiation continues the MWCNT breaks down until there is only a single wall carbon nanotube (SWCNT). Then, when the SWCNT breaks, an atomic carbon chain is formed, lasts for several seconds under the radiation and finally breaks. This demonstrates the stability of this carbon structure.

  2. Amino and thiol modified magnetic multi-walled carbon nanotubes for the simultaneous removal of lead, zinc, and phenol from aqueous solutions

    Science.gov (United States)

    Jiang, Lili; Li, Shujun; Yu, Haitao; Zou, Zongshu; Hou, Xingang; Shen, Fengman; Li, Chuantong; Yao, Xiayan

    2016-04-01

    The novel functionalization of multi-walled carbon nanotubes (MWCNTs) was synthesized by reacting trimethoxysilylpropanethiol (MPTs), hydrazine, ammonium ferrous sulfate, and ammonium ferric sulfate in sequence as efficient ways to introduce Fe3O4, amino and thiol groups onto the nanotubes sidewalls. The magnetic MWCNTs composite material (N2H4-SH-Fe3O4/o-MWCNTs) was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, x-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy and magnetization curve. The results revealed that MPTs and hydrazine were coated on the surface of N2H4-SH-Fe3O4/o-MWCNTs. A series of batch adsorption experiments were conducted to study the experimental conditions, such as pH, contact time, initial concentrations and temperatures, which affected the adsorption process. The adsorption experiment results showed that the maximum equilibrium adsorption capacity of N2H4-SH-Fe3O4/o-MWCNTs for lead, zinc and phenol was 195.81 mg/g, 169.89 mg/g and 38.97 mg/g at pH 6, respectively. The adsorption isotherm was better fitted by the Freundlich model, and the adsorption kinetics was consistent with pseudo-second order kinetics model. Furthermore, thermodynamic data showed that the adsorption process was spontaneous and exothermic. These results indicated that N2H4-SH-Fe3O4/o-MWCNTs may be promising surface modified materials for removing heavy metal ions and phenol from aqueous solutions.

  3. Enhanced electrochemical performance of multi-walled carbon nanotubes modified Li{sub 2}FeSiO{sub 4}/C cathode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Gang [College of Mechanical and Material Engineering, Three Gorges University, 8 Daxue Road, Yichang 443002 (China); Zhang, Lu-Lu, E-mail: luluzhang924@gmail.com [College of Mechanical and Material Engineering, Three Gorges University, 8 Daxue Road, Yichang 443002 (China); Yang, Xue-Lin, E-mail: xlyang@ctgu.edu.cn [College of Mechanical and Material Engineering, Three Gorges University, 8 Daxue Road, Yichang 443002 (China); Duan, Song [College of Mechanical and Material Engineering, Three Gorges University, 8 Daxue Road, Yichang 443002 (China); Liang, Gan [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Huang, Yun-Hui [State Key Laboratory of Materials Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074 (China)

    2013-09-05

    Graphical abstract: The multi-walled carbon nanotubes (MWCNTs) modified Li{sub 2}FeSiO{sub 4}/C composite is synthesized via a citric acid-based sol–gel method. The as-prepared Li{sub 2}FeSiO{sub 4}/C/MWCNTs electrode displays a remarkably enhanced high-rate performance and cycling stability because of the effective conducting network between the MWCNTs and the Li{sub 2}FeSiO{sub 4}/C particles. Highlights: •Nano-Li{sub 2}FeSiO{sub 4}/C/MWCNTs composite was successfully synthesized via a citric acid-based sol–gel method. •High conducting network were attained for Li{sub 2}FeSiO{sub 4}/C/MWCNTs. •The Li{sub 2}FeSiO{sub 4}/C/MWCNTs electrode can extract more than 1 mol Li{sup +} at 0.1 C. •The as-prepared Li{sub 2}FeSiO{sub 4}/C/MWCNTs electrode displays a remarkably enhanced high-rate performance and cycling stability. -- Abstract: The multi-walled carbon nanotubes (MWCNTs) modified Li{sub 2}FeSiO{sub 4}/C composite is synthesized via a citric acid-based sol–gel method, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, galvanostatic charge/discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) tests. The Li{sup +} diffusion coefficient in Li{sub 2}FeSiO{sub 4}/C/MWCNTs is larger than that in Li{sub 2}FeSiO{sub 4}/C. Compared with Li{sub 2}FeSiO{sub 4}/C, Li{sub 2}FeSiO{sub 4}/C/MWCNTs electrode can extract more than 1 mol Li{sup +} and exhibit better electrochemical performance with a high discharge capacity of 206.8 mA h g{sup −1} in the second cycle, especially, an excellent high-rate capacity and cycle stability. The enhanced electrochemical performance is attributed to the reduced particle size and the high conducting network between the MWCNTs and the Li{sub 2}FeSiO{sub 4}/C particles.

  4. Pulsed laser deposition of carbon nanotube and polystyrene-carbon nanotube composite thin films

    Science.gov (United States)

    Stramel, A. A.; Gupta, M. C.; Lee, H. R.; Yu, J.; Edwards, W. C.

    2010-12-01

    In this work, we report on the fabrication of carbon nanotube thin films via pulsed laser deposition using a pulsed, diode pumped, Tm:Ho:LuLF laser with 2 μm wavelength. The thin films were deposited on silicon substrates using pure carbon nanotube targets and polystyrene-carbon nanotube composite targets. Raman spectra, scanning electron micrographs, and transmission electron micrographs show that carbon nanotubes are present in the deposited thin films, and that the pulsed laser deposition process causes minimal degradation to the quality of the nanotubes when using pure carbon nanotube targets.

  5. Bloch oscillations in carbon nanotubes.

    Science.gov (United States)

    Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.

  6. Bloch oscillations in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jodar, Esther; Perez-Garrido, Antonio [Departamento Fisica Aplicada, Antiguo Hospital de Marina Campus Muralla del Mar, UPCT, Cartagena 30202 Murcia (Spain); Rojas, Fernando [Centro de Nanociencias y Nanotecnologia-UNAM, Apartado Postal 356, Ensenada, Baja California 22800 (Mexico)], E-mail: ejodar@upct.es

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case. (fast track communication)

  7. Nonlinear buckling analyses of a small-radius carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ning, E-mail: liuxiao@ase.buaa.edu.cn; Li, Min; Jia, Jiao [School of Aeronautic Science and Engineering, Beihang University, Beijing 100091 (China); Wang, Yong-Gang [Department of Applied Mechanics, China Agricultural University, Beijing 100083 (China)

    2014-04-21

    Carbon nanotube (CNT) was first discovered by Sumio Iijima. It has aroused extensive attentions of scholars from all over the world. Over the past two decades, we have acquired a lot of methods to synthesize carbon nanotubes and learn their many incredible mechanical properties such as experimental methods, theoretical analyses, and computer simulations. However, the studies of experiments need lots of financial, material, and labor resources. The calculations will become difficult and time-consuming, and the calculations may be even beyond the realm of possibility when the scale of simulations is large, as for computer simulations. Therefore, it is necessary for us to explore a reasonable continuum model, which can be applied into nano-scale. This paper attempts to develop a mathematical model of a small-radius carbon nanotube based on continuum theory. An Isotropic circular cross-section, Timoshenko beam model is used as a simplified mechanical model for the small-radius carbon nanotube. Theoretical part is mainly based on modified couple stress theory to obtain the numerical solutions of buckling deformation. Meanwhile, the buckling behavior of the small radius carbon nanotube is simulated by Molecular Dynamics method. By comparing with the numerical results based on modified couple stress theory, the dependence of the small-radius carbon nanotube mechanical behaviors on its elasticity constants, small-size effect, geometric nonlinearity, and shear effect is further studied, and an estimation of the small-scale parameter of a CNT (5, 5) is obtained.

  8. Nonlinear buckling analyses of a small-radius carbon nanotube

    Science.gov (United States)

    Liu, Ning; Wang, Yong-Gang; Li, Min; Jia, Jiao

    2014-04-01

    Carbon nanotube (CNT) was first discovered by Sumio Iijima. It has aroused extensive attentions of scholars from all over the world. Over the past two decades, we have acquired a lot of methods to synthesize carbon nanotubes and learn their many incredible mechanical properties such as experimental methods, theoretical analyses, and computer simulations. However, the studies of experiments need lots of financial, material, and labor resources. The calculations will become difficult and time-consuming, and the calculations may be even beyond the realm of possibility when the scale of simulations is large, as for computer simulations. Therefore, it is necessary for us to explore a reasonable continuum model, which can be applied into nano-scale. This paper attempts to develop a mathematical model of a small-radius carbon nanotube based on continuum theory. An Isotropic circular cross-section, Timoshenko beam model is used as a simplified mechanical model for the small-radius carbon nanotube. Theoretical part is mainly based on modified couple stress theory to obtain the numerical solutions of buckling deformation. Meanwhile, the buckling behavior of the small radius carbon nanotube is simulated by Molecular Dynamics method. By comparing with the numerical results based on modified couple stress theory, the dependence of the small-radius carbon nanotube mechanical behaviors on its elasticity constants, small-size effect, geometric nonlinearity, and shear effect is further studied, and an estimation of the small-scale parameter of a CNT (5, 5) is obtained.

  9. Synthesis of carbon nanotubes with Ni/CNTs catalyst

    Institute of Scientific and Technical Information of China (English)

    李春华; 姚可夫; 阮殿波; 梁吉; 徐才录; 吴德海

    2003-01-01

    Carbon nanotubes (CNTs), owing to their large specific area, good chemical stability and modifiable surface properties after acidic or basic treatment, can be used as catalytic support materials. In this paper, the activities and selectivities of two catalysts, i. e. Ni catalyst supported by carbon nanotubes (Ni/CNTs) and that supported by diatomite (Ni/SiO2), are compared. It is found that the quality of the carbon nanotubes synthesized by the two catalysts is similar, but the yield of the former is 1.5 times higher than that of the latter. The excellent performance of the Ni/CNTs catalyst should be ascribed to the larger specific surface area and proper pore distribution and the structure of the carbon nanotube support.

  10. Targeted and pH-responsive delivery of doxorubicin to cancer cells using multifunctional dendrimer-modified multi-walled carbon nanotubes.

    Science.gov (United States)

    Wen, Shihui; Liu, Hui; Cai, Hongdong; Shen, Mingwu; Shi, Xiangyang

    2013-09-01

    We report the use of multifunctional dendrimer-modified multi-walled carbon nanotubes (MWCNTs) for targeted and pH-responsive delivery of doxorubicin (DOX) into cancer cells. In this study, amine-terminated generation 5 poly(amidoamine) (PAMAM) dendrimers modified with fluorescein isothiocyanate (FI) and folic acid (FA) were covalently linked to acid-treated MWCNTs, followed by acetylation of the remaining dendrimer terminal amines to neutralize the positive surface potential. The formed multifunctional MWCNTs (MWCNT/G5.NHAc-FI-FA) were characterized via different techniques. Then, the MWCNT/G5.NHAc-FI-FA was used to load DOX for targeted and pH-responsive delivery to cancer cells overexpressing high-affinity folic acid receptors (FAR). We showed that the MWCNT/G5.NHAc-FI-FA enabled a high drug payload and encapsulation efficiency both up to 97.8% and the formed DOX/MWCNT/G5.NHAc-FI-FA complexes displayed a pH-responsive release property with fast DOX release under acidic environment and slow release at physiological pH conditions. Importantly, the DOX/MWCNT/G5.NHAc-FI-FA complexes displayed effective therapeutic efficacy, similar to that of free DOX, and were able to target to cancer cells overexpressing high-affinity FAR and effectively inhibit the growth of the cancer cells. The synthesized multifunctional dendrimer-modified MWCNTs may be used as a targeted and pH-responsive delivery system for targeting therapy of different types of cancer cells.

  11. Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.

    Science.gov (United States)

    Briggs, Nicholas M; Weston, Javen S; Li, Brian; Venkataramani, Deepika; Aichele, Clint P; Harwell, Jeffrey H; Crossley, Steven P

    2015-12-01

    Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability.

  12. Determination of Catechol Based on Carbon Nanotube Modified Glassy Carbon Electrode%碳纳米管修饰玻碳电极测定邻苯二酚的研究

    Institute of Scientific and Technical Information of China (English)

    崔艳萍; 王卫星; 王小龙

    2011-01-01

    文章借助循环伏安法(CV)研究了邻二苯酚(CAT)在碳纳米管修饰玻碳电极(CNTs/GCE)表面的电催化氧化行为.试验结果表明:CNTs/GCE对邻二苯酚的氧化过程表现出良好的催化活性,其响应峰电流与裸GCE相比增加了10倍以上;在最佳响应条件下,在0.25~2.0 mmol/L的浓度范围内,邻苯二酚的催化氧化峰电流与浓度呈良好的线性关系;并对模拟废水中的邻苯二酚进行了回收试验.%Carbon nanotubes (CNTs) were loaded on the glassy carbon electrode to prepare carbon nanotube modified glassy carbon electrode (CNTs/GCE). And the electrocatalytic oxidation behavior of catechol was investigated on this modified electrode by cyclic voltammetry (CV) of the electrochemical methods. Results show that good electrocatalytic activity for catechol oxidation could be observed at CNTs/GCE. Compared with bare GCE, the response peak current of CNTs/GCE had an increase of more than lOtimes. Under the optimal condition of response, the oxidation peak current were increased linear with the concentrations of catechol at the range 0.25-2.0 mmol/L. And the recovery test of catechol in simulating wastewater was satisfactory.

  13. Pt nanoparticle modified single walled carbon nanotube network electrodes for electrocatalysis: control of the specific surface area over three orders of magnitude

    NARCIS (Netherlands)

    Miller, T.S.; Sansuk, S.; Lai, S.C.S.; Macpherson, J.V.; Unwin, P.R.

    2015-01-01

    The electrodeposition of Pt nanoparticles (NPs) on two-dimensional single walled carbon nanotube (SWNT) network electrodes is investigated as a means of tailoring electrode surfaces with a well-defined amount of electrocatalytic material. Both Pt NP deposition and electrocatalytic studies are undert

  14. Simultaneous trace-levels determination of Hg(II) and Pb(II) ions in various samples using a modified carbon paste electrode based on multi-walled carbon nanotubes and a new synthesized Schiff base.

    Science.gov (United States)

    Afkhami, Abbas; Bagheri, Hasan; Khoshsafar, Hosein; Saber-Tehrani, Mohammad; Tabatabaee, Masoumeh; Shirzadmehr, Ali

    2012-10-09

    A modified carbon paste electrode based on multi-walled carbon nanotubes (MWCNTs) and 3-(4-methoxybenzylideneamino)-2-thioxothiazolodin-4-one as a new synthesized Schiff base was constructed for the simultaneous determination of trace amounts of Hg(II) and Pb(II) by square wave anodic stripping voltammetry. The modified electrode showed an excellent selectivity and stability for Hg(II) and Pb(II) determinations and for accelerated electron transfer between the electrode and the analytes. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as pH, deposition potential and deposition time were optimized for the purpose of determination of traces of metal ions at pH 3.0. Under optimal conditions the limits of detection, based on three times the background noise, were 9.0×10(-4) and 6.0×10(-4) μmol L(-1) for Hg(II) and Pb(II) with a 90 s preconcentration, respectively. In addition, the modified electrode displayed a good reproducibility and selectivity, making it suitable for the simultaneous determination of Hg(II) and Pb(II) in real samples such as sea water, waste water, tobacco, marine and human teeth samples.

  15. Application of an enzyme-based biofuel cell containing a bioelectrode modified with deoxyribonucleic acid-wrapped single-walled carbon nanotubes to serum.

    Science.gov (United States)

    Lee, Jin Young; Shin, Hyun Yong; Kang, Seong Woo; Park, Chulhwan; Kim, Seung Wook

    2011-01-01

    Enzyme-based biofuel cells (EFCs) are a form of biofuel cells (BFCs) that can utilize redox enzymes as biocatalysts. Applications of an EFC to an implantable system are evaluated under mild conditions, such as ambient temperature or neutral pH. In the present study, an EFC containing a bioelectrode modified with deoxyribonucleic acid (DNA)-wrapped single-walled carbon nanotubes (SWNTs) was applied to a serum system. The protection of immobilized glucose oxidase (GOD) using DNA-wrapped SWNTs was investigated in a trypsin environment, which can exist in a serum. GOD is immobilized by masking the active site onto the anode electrode. The anode/cathode system in the cell was composed of GOD/laccase as the biocatalysts and glucose/oxygen as the substrates in serum. The electrical properties of the anode in serum according to cyclic voltammetry (CV cycle) were improved using the DNA-wrapped SWNTs. Overall, an EFC that employed DNA-wrapped SWNTs and GOD immobilization in conjunction with protection of the active site increased the stability of GOD in serum, which enabled a high level of power production (ca. 190 μW/cm(2)) for up to 1 week.

  16. Single-walled carbon nanotubes noncovalently functionalized with lipid modified polyethylenimine for siRNA delivery in vitro and in vivo.

    Science.gov (United States)

    Siu, King S; Zheng, Xiufen; Liu, Yanling; Zhang, Yujuan; Zhang, Xusheng; Chen, Di; Yuan, Ken; Gillies, Elizabeth R; Koropatnick, James; Min, Wei-Ping

    2014-10-15

    siRNA can downregulate the expression of specific genes. However, delivery to specific cells and tissues in vivo presents significant challenges. Modified carbon nanotubes (CNTs) have been shown to protect siRNA and facilitate its entry into cells. However, simple and efficient methods to functionalize CNTs are needed. Here, noncovalent functionalization of CNTs is performed and shown to effectively deliver siRNA to target cells. Specifically, single-walled CNTs were functionalized by noncovalent association with a lipopolymer. The lipopolymer (DSPE-PEG) was composed of a phospholipid 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) and poly(ethylene glycol) (PEG). Three different ratios of polyethylenimine (PEI) to DSPE-PEG were synthesized and characterized and the products were used to disperse CNTs. The resulting materials were used for siRNA delivery in vitro and in vivo. The structural, biophysical, and biological properties of DGI/C and their complexes formed with siRNA were investigated. Cytotoxicity of the materials was low, and effective gene silencing in B16-F10 cells was demonstrated in vitro. In addition, significant uptake of siRNA as well as gene silencing in the liver was found following intravenous injection. This approach provides a new strategy for siRNA delivery and could provide insight for the development of noncovalently functionalized CNTs for siRNA therapy.

  17. Highly sensitive chemiluminescence immunoassay on chitosan membrane modified paper platform using TiO2 nanoparticles/multiwalled carbon nanotubes as label.

    Science.gov (United States)

    Li, Weiping; Ge, Shenguang; Wang, Shoumei; Yan, Mei; Ge, Lei; Yu, Jinghua

    2013-01-01

    A highly sensitive chemiluminescence (CL) immunoassay was incorporated into a low-cost microfluidic paper-based analytical device (μ-PAD) to fabricate a facile paper-based CL immunodevice (denoted as μ-PCLI). This μ-PCLI was constructed by covalently immobilizing capture antibody on a chitosan membrane modified μ-PADs, which was developed by simple wax printing methodology. TiO2 nanoparticles coated multiwalled carbon nanotubes (TiO2/MWCNTs) were synthesized as an amplification catalyst tag to label signal antibody (Ab2). After sandwich-type immunoreactions, the TiO2/MWCNTs were captured on the surface of μ-PADs to catalyze the luminol-p-iodophenol-H2O2 CL system, which produced an enhanced CL emission. Using prostate-specific antigen as a model analyte, the approach provided a good linear response range from 0.001 to 20 ng/mL with a low detection limit of 0.8 pg/mL under optimal conditions. This μ-PCLI showed good reproducibility, selectivity and stability. The assay results of prostate-specific antigen in clinical serum samples were in good agreement with that obtained by commercially used electrochemiluminescence methods at the Cancer Research Center of Shandong Tumor Hospital (Jinan, Shandong Province, China). This μ-PCLI could be very useful to realize highly sensitive, qualitative point-of-care testing in developing or developed countries.

  18. Quantitative determination and toxicity evaluation of 2,4-dichlorophenol using poly(eosin Y)/hydroxylated multi-walled carbon nanotubes modified electrode

    Science.gov (United States)

    Zhu, Xiaolin; Zhang, Kexin; Wang, Chengzhi; Guan, Jiunian; Yuan, Xing; Li, Baikun

    2016-12-01

    This study aimed at developing simple, sensitive and rapid electrochemical approach to quantitatively determine and assess the toxicity of 2,4-dichlorophenol (2,4-DCP), a priority pollutant and has potential risk to public health through a novel poly(eosin Y, EY)/hydroxylated multi-walled carbon nanotubes composite modified electrode (PEY/MWNTs-OH/GCE). The distinct feature of this easy-fabricated electrode was the synergistic coupling effect between EY and MWNTs-OH that enabled a high electrocatalytic activity to 2,4-DCP. Under optimum conditions, the oxidation peak current enhanced linearly with concentration increasing from 0.005 to 0.1 μM and 0.2 to 40.0 μM, and revealed the detection limit of 1.5 nM. Moreover, the PEY/MWNTs-OH/GCE exhibited excellent electrocatalytic activity toward intracellular electroactive species. Two sensitive electrochemical signals ascribed to guanine/xanthine and adenine/hypoxanthine in human hepatoma (HepG2) cells were detected simultaneously. The sensor was successfully applied to evaluate the toxicity of 2,4-DCP to HepG2 cells. The IC50 values based on the two electrochemical signals are 201.07 and 252.83 μM, respectively. This study established a sensitive platform for the comprehensive evaluation of 2,4-DCP and posed a great potential to simplify environmental toxicity monitoring.

  19. Electrochemical sensor based on molecularly imprinted film at polypyrrole-sulfonated graphene/hyaluronic acid-multiwalled carbon nanotubes modified electrode for determination of tryptamine.

    Science.gov (United States)

    Xing, Xianrong; Liu, Su; Yu, Jinghua; Lian, Wenjing; Huang, Jiadong

    2012-01-15

    An imprinted electrochemical sensor based on polypyrrole-sulfonated graphene (PPy-SG)/hyaluronic acid-multiwalled carbon nanotubes (HA-MWCNTs) for sensitive detection of tryptamine was presented. Molecularly imprinted polymers (MIPs) were synthesized by electropolymerization using tryptamine as the template, and para-aminobenzoic acid (pABA) as the monomer. The surface feature of the modified electrode was characterized by cyclic voltammetry (CV). The proposed sensor was tested by chronoamperometry. Several important parameters controlling the performance of the molecularly imprinted sensor were investigated and optimized. The results showed that the PPy-SG composites films showed improved conductivity and electrochemical performances. HA-MWCNTs bionanocomposites could enhance the current response evidently. The good selectivity of the sensor allowed three discriminations of tryptamine from interferents, which include tyramine, dopamine and tryptophan. Under the optimal conditions, a linear ranging from 9.0×10(-8) mol L(-1) to 7.0×10(-5) mol L(-1) for the detection of tryptamine was observed with the detection limit of 7.4×10(-8) mol L(-1) (S/N=3). This imprinted electrochemical sensor was successfully employed to detect tryptamine in real samples.

  20. Multi-walled carbon nanotube modified dummy-template magnetic molecularly imprinted microspheres as solid-phase extraction material for the determination of polychlorinated biphenyls in fish.

    Science.gov (United States)

    Du, Xiaowen; Lin, Saichai; Gan, Ning; Chen, Xidong; Cao, Yuting; Li, Tianhua; Zhan, Pan

    2014-07-01

    Novel multi-walled carbon nanotube modified dummy-template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core-shell Fe3 O4 @SiO2 nanoparticles were employed as magnetic support. 3,4-Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross-linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo-second-order kinetic equation and also exhibited a three-stage intra-particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid-phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028-0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.

  1. Preparation, characterization and adsorption properties of chitosan modified magnetic graphitized multi-walled carbon nanotubes for highly effective removal of a carcinogenic dye from aqueous solution

    Science.gov (United States)

    Zhu, HuaYue; Fu, YongQian; Jiang, Ru; Yao, Jun; Liu, Li; Chen, YanWen; Xiao, Ling; Zeng, GuangMing

    2013-11-01

    Novel chitosan-modified magnetic graphitized multi-walled carbon nanotubes (CS-m-GMCNTs) were synthesized via a suspension cross-linking method. Composition, morphology and magnetic properties of as-prepared CS-m-GMCNTs were characterized by XRD, SEM-EDS, BET and VSM. The large saturation magnetization (12.27 emu g-1) allows fast separation of CS-m-GMCNTs from treated aqueous solution. The adsorption of congo red (CR) on CS-m-GMCNTs was strongly dependent on pH, temperature of the aqueous phase and adsorbent dosage. Up to 100 and 94.58% color removal could be achieved in 100 min contact time with 10 and 50 mg L-1 of initial concentrations, respectively. The adsorption capacity of CR onto CS-m-GMCNTs could reach 262.9 mg g-1. The pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.999) was suitable to describe the process of CR adsorption onto CS-m-GMCNTs. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model. Values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process was strongly dependent on temperature of the aqueous phase, and spontaneous and endothermic process in nature. Therefore, CS-m-GMCNTs adsorbent displays main advantages of excellent dispersion, convenience separation and high adsorption capacity, which implies their potential application in the environmental cleanup.

  2. Pressure-Induced Interlinking of Carbon Nanotubes

    OpenAIRE

    Yildirim, T.; Gulseren, O.; Kilic, C.; Ciraci, S.

    2000-01-01

    We predict new forms of carbon consisting of one and two dimensional networks of interlinked single wall carbon nanotubes, some of which are energetically more stable than van der Waals packing of the nanotubes on a hexagonal lattice. These interlinked nanotubes are further transformed with higher applied external pressures to more dense and complicated stable structures, in which curvature-induced carbon sp$^{3}$ re-hybridizations are formed. We also discuss the energetics of the bond format...

  3. Different Technical Applications of Carbon Nanotubes

    OpenAIRE

    Abdalla, S; Al-Marzouki, F.; Ahmed A. Al-Ghamdi; Abdel-Daiem, A.

    2015-01-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc....

  4. Faster and Smaller with Carbon Nanotubes?

    OpenAIRE

    Seidel, Robert V.; Graham, Andrew P.; Duesberg, Georg S.; Liebau, Maik; Unger, Eugen; Kreupl, Franz; Hoenlein, Wolfgang

    2004-01-01

    Carbon Nanotubes seem to be one of the most promising candidates for nanoelectronic devices beyond presumable scaling limits of silicon and compound semiconductors and independent from lithographic limitations. Discovered only about a decade ago, there has been a tremendous advance in the field of carbon nanotubes. Their exciting properties, especially with respect to electronic applications, and their fabrication methods will be discussed. A variety of Carbon Nanotube...

  5. Carbon Nanotubes and Related Structures

    Directory of Open Access Journals (Sweden)

    Kingsuk Mukhopadhyay

    2008-07-01

    Full Text Available Carbon nanotubes have attracted the fancy of many scientists world wide. The small dimensions,strength, and the remarkable physical properties of these structures make them a unique material with a whole range of promising applications. In this review, the structural aspects, the advantages and disadvantages of different for their procedures synthesis, the qualitative and quantitative estimation of carbon nanotubes by different analytical techniques, the present status on their applications as well as the current challenges faced in the application field, national, in particular DRDO, DMSRDE status, and interest in this field, have been discussed.Defence Science Journal, 2008, 58(4, pp.437-450, DOI:http://dx.doi.org/10.14429/dsj.58.1666

  6. Ballistic Fracturing of Carbon Nanotubes.

    Science.gov (United States)

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome.

  7. Carbon Nanotubes: Molecular Electronic Components

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  8. Torsional Carbon Nanotube Artificial Muscles

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  9. Carbon nanotubes in tissue engineering.

    Science.gov (United States)

    Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

    2014-01-01

    As a result of their peculiar features, carbon nanotubes (CNTs) are emerging in many areas of nanotechnology applications. CNT-based technology has been increasingly proposed for biomedical applications, to develop biomolecule nanocarriers, bionanosensors and smart material for tissue engineering purposes. In the following chapter this latter application will be explored, describing why CNTs can be considered an ideal material able to support and boost the growth and the proliferation of many kinds of tissues.

  10. A Thermal Model for Carbon Nanotube Interconnects

    Science.gov (United States)

    Mohsin, Kaji Muhammad; Srivastava, Ashok; Sharma, Ashwani K.; Mayberry, Clay

    2013-01-01

    In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI) interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT) interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  11. OPPORTUNITIES OF BIOMEDICAL USE OF CARBON NANOTUBES

    Directory of Open Access Journals (Sweden)

    I. V. Mitrofanova

    2014-01-01

    Full Text Available Nanomaterials  –  materials,  whouse  structure  elements  has  proportions  doesn’t  exceed  100  nm.  In superdispersed state matter acquire new properties. In the last decade, carbon nanotubes become the most popular nanomaterials, that cause attention of representatives of various scientific field. The сarbon nanotubes offer new opportunities for biological and medical applications: imaging at the molecular, cellular and tissue levels, biosensors and electrodes based on carbon nanotubes, target delivery of various substances, radiation and photothermal therapy. The most promising of carbon nanotubes in the context of biomedical applications is their ability to penetrate the various tissues of the body and carry large doses of agents, providing diagnostic and therapeutic effects. Functionalized nanotubes are biodegradable. Other current direction of using carbon nanotubes in medicine and biology is to visualize objects on the molecular, cellular and tissue level. Associated with carbon nanotubes contrasting substances improve the visualization of cells and tissues, which can detected new patterns of development of the pathological process. Due to the vagueness of the question of biocompatibility and cytotoxicity of carbon nanotubes possibility of their practical application is hampered. Before the introduction of carbon nanotubes into practical health care is necessary to provide all the possible consequences of using nanotubes. High rates of properties and development of new nanostructures based on carbon nanotubes in the near future will lead to new advances related to the application and development of new parameters that will determine their properties and effects. In these review attention is paid to the structure, physico-chemical properties of nanotubes, their functionalization, pharmacokinetics and pharmacodynamics and all aspects of using of carbon nanotubes.

  12. The Effect of Functionalization Carbon Nanotubes (CNTs) on the Performance of PES-CNTs Mixed Matrix Membrane

    OpenAIRE

    Ahmad Mustafa; Tutuk Djoko Kusworo; Abdullah Busairi; Ahmad Fauzi Ismail

    2010-01-01

    A new type of mixed matrix membrane consisting of functionalized carbon nanotubes (CNTs) and polyethersulfone (PES) is prepared for biogas purification. PES mixed matrix membrane with and without modification of carbon nanotubes were prepared by a dry/wet phase inversion technique using a pneumatically flat sheet membrane casting machine system. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using Dynasylan Ameo (DA) silane agent to all...

  13. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.;

    2008-01-01

    an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From......In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... are known. The parameters of the liquid surface model and its potential applications are discussed. The model has been suggested for open end and capped nanotubes. The influence of the catalytic nanoparticle, atop which nanotubes grow, on the nanotube stability is also discussed. The suggested model gives...

  14. Carboxyl-modified single-wall carbon nanotubes improve bone tissue formation in vitro and repair in an in vivo rat model

    Directory of Open Access Journals (Sweden)

    Barrientos-Durán A

    2014-09-01

    Full Text Available Antonio Barrientos-Durán,1,5,* Ellen M Carpenter,2 Nicole I zur Nieden,3 Theodore I Malinin,4 Juan Carlos Rodríguez-Manzaneque,5 Laura P Zanello1,* 1Department of Biochemistry, University of California Riverside, Riverside, CA, USA; 2Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine, South Los Angeles, CA, USA; 3Department of Cell Biology and Neuroscience, Stem Cell Center, College of Natural and Agricultural Sciences, University of California Riverside, Riverside, CA, USA; 4Tissue Bank, Department of Orthopedics, University of Miami Miller School of Medicine, Miami, FL, USA; 5Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO, Granada, Spain *These authors contributed equally to this workAbstract: 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 carbon nanotubes (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 µg/mL, these levels were never achieved by release from sprayed SWCNTs, warranting the approach taken. In vivo, human allografts formed by the

  15. General hypothesis and shell model for the synthesis of semiconductor nanotubes, including carbon nanotubes

    Science.gov (United States)

    Mohammad, S. Noor

    2010-09-01

    Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology development. The fundamental physics and growth kinetics of these nanotubes are still obscured. Various models developed to elucidate the growth suffer from limited applicability. An in-depth investigation of the fundamentals of nanotube growth has, therefore, been carried out. For this investigation, various features of nanotube growth, and the role of the foreign element catalytic agent (FECA) in this growth, have been considered. Observed growth anomalies have been analyzed. Based on this analysis, a new shell model and a general hypothesis have been proposed for the growth. The essential element of the shell model is the seed generated from segregation during growth. The seed structure has been defined, and the formation of droplet from this seed has been described. A modified definition of the droplet exhibiting adhesive properties has also been presented. Various characteristics of the droplet, required for alignment and organization of atoms into tubular forms, have been discussed. Employing the shell model, plausible scenarios for the formation of carbon nanotubes, and the variation in the characteristics of these carbon nanotubes have been articulated. The experimental evidences, for example, for the formation of shell around a core, dipole characteristics of the seed, and the existence of nanopores in the seed, have been presented. They appear to justify the validity of the proposed model. The diversities of nanotube characteristics, fundamentals underlying the creation of bamboo-shaped carbon nanotubes, and the impurity generation on the surface of carbon nanotubes have been elucidated. The catalytic action of FECA on growth has been quantified. The applicability of the proposed model to the nanotube growth by a variety of mechanisms has been elaborated. These mechanisms include the vapor-liquid-solid mechanism, the oxide-assisted growth mechanism, the self

  16. 超支化聚合物修饰碳纳米管的研究进展%Research Progress of Carbon Nanotubes Modified by Hyperbranched Polymer

    Institute of Scientific and Technical Information of China (English)

    张梓军; 颜红侠; 管兴华; 刘超

    2012-01-01

    碳纳米管( CNTs)具有极高的杨氏模量、硬度和韧性、良好的导电性和导热性,但由于其分散性差,限制了其应用范围.超支化聚合物( HBP)具有低粘度、高流变性和良好的溶解性,特别是末端含有大量的活性官能团.用HBP修饰CNTs,不仅可以提高CNTs在聚合物基体中的分散性,改善CNTs与基体之间的相容性和界面粘接性能,还可以赋予CNTs新的功能.因此,综述了超支化聚合物改性CNTs的方法,包括直接改性法,表面引发聚合法等方法,并指出了每种改性方法的优缺点及其发展前景.%Although carbon nanotubes (CNTs) have many good properties, such as high Young modulus, hardness and toughness, good electrical conductivity and thermal conductivity, its poor dispersibility have imposed great limitations to its applications and development Hyperbranched polymer (HBP) has low viscosity, high rheologi-cal behaviour and good solubility, especially its terminal end with lots of active functional groups. So CNTs modified by HBP can not only improve dispersibility of CNTs, enhance the compatibility and interface adhesion between polymer matrix and CNTs, but also endow CNTs with new properties. So in this article, methods of hyperbranched-poly-mer-modified CNTs are summarized, including direct modification and surface-initiated polymerization and so on. The merit and demerit of each method and its prospects in the future are also pointed out.

  17. Engineering carbon nanotubes and nanotube circuits using electrical breakdown.

    Science.gov (United States)

    Collins, P G; Arnold, M S; Avouris, P

    2001-04-27

    Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or "ropes" of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs.

  18. Freeze-drying synthesis of three-dimensional porous LiFePO4 modified with well-dispersed nitrogen-doped carbon nanotubes for high-performance lithium-ion batteries

    Science.gov (United States)

    Tu, Xiaofeng; Zhou, Yingke; Song, Yijie

    2017-04-01

    The three-dimensional porous LiFePO4 modified with uniformly dispersed nitrogen-doped carbon nanotubes has been successfully prepared by a freeze-drying method. The morphology and structure of the porous composites are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the electrochemical performances are evaluated using the constant current charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The nitrogen-doped carbon nanotubes are uniformly dispersed inside the porous LiFePO4 to construct a superior three-dimensional conductive network, which remarkably increases the electronic conductivity and accelerates the diffusion of lithium ion. The porous composite displays high specific capacity, good rate capability and excellent cycling stability, rendering it a promising positive electrode material for high-performance lithium-ion batteries.

  19. Plasticity and Kinky Chemistry of Carbon Nanotubes

    Science.gov (United States)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  20. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane....... The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an electric field, thus enabling nanotube integration in microsystems. Dielectrophoresis offers also...... the potential of distinguishing between nanotubes of different electrical properties, which is very important for the optimisation of the properties of the carbon nanotube sensors. Various cantilever and planar structures were designed, fabricated and tested both with multi-walled and single-walled carbon...

  1. Sorting carbon nanotubes for electronics.

    Science.gov (United States)

    Martel, Richard

    2008-11-25

    Because of their unique structure and composition, single-wall carbon nanotubes (SWNTs) are at the interface between molecules and crystalline solids. They also present properties that are ideal for making lightweight, inexpensive, and flexible electronics. The raw material is composed of a heterogeneous mixture of SWNTs that differ in helicity and diameter and, therefore, requires purification and separation. In a series of groundbreaking experiments, a robust process serving this purpose was developed based on SWNTs encapsulated in surfactants and water. Ultracentrifugation in a density gradient combined with surfactant mixtures provided buoyant density differences, enabling enrichment for both diameter and electronic properties. A new paper in this issue explores further the process through the hydrodynamic properties of SWNT-surfactant complexes. The study reveals that we have just begun to uncover the dynamics and properties of nanotube-surfactant interactions and highlights the potential that could be gained from a better understanding of their chemistry. The time scale of integration of carbon nanotubes into electronics applications remains unclear, but the recent developments in sorting out SWNTs paves the way for improving on the properties of network-based SWNTs.

  2. Enhancing and redirecting carbon nanotube photoluminescence by an optical antenna.

    Science.gov (United States)

    Böhmler, Miriam; Hartmann, Nicolai; Georgi, Carsten; Hennrich, Frank; Green, Alexander A; Hersam, Mark C; Hartschuh, Achim

    2010-08-02

    We observe the angular radiation pattern of single carbon nanotubes' photoluminescence in the back focal plane of a microscope objective and show that the emitting nanotube can be described by a single in-plane point dipole. The near-field interaction between a nanotube and an optical antenna modifies the radiation pattern that is now dominated by the antenna characteristics. We quantify the antenna induced excitation and radiation enhancement and show that the radiative rate enhancement is connected to a directional redistribution of the emission.

  3. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  4. Amino and thiol modified magnetic multi-walled carbon nanotubes for the simultaneous removal of lead, zinc, and phenol from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Lili, E-mail: jianglili2002@163.com [School of Metallurgy, Northeastern University, No. 3-11, Wenhua Road, Heping District, Shenyang, Liaoning Province (China); School of Material Science and Technology, Lanzhou University of Technology, Langongping Road, Lanzhou 730050, Gansu Province (China); Li, Shujun, E-mail: LSJ002@163.com [School of Material Science and Technology, Lanzhou University of Technology, Langongping Road, Lanzhou 730050, Gansu Province (China); Yu, Haitao, E-mail: yuhaitao7707@163.com [Department of Medical Laboratory, The First Hospital of Lanzhou University, No. 1, Donggang Road, Chengguan District, Lanzhou 730000, Gansu Province (China); Zou, Zongshu, E-mail: zouzs@mail.neu.edu.cn [School of Metallurgy, Northeastern University, No. 3-11, Wenhua Road, Heping District, Shenyang, Liaoning Province (China); Hou, Xingang, E-mail: houxg1958@163.com [School of Material Science and Technology, Lanzhou University of Technology, Langongping Road, Lanzhou 730050, Gansu Province (China); Shen, Fengman, E-mail: shenfm@mail.neu.edu.cn [School of Metallurgy, Northeastern University, No. 3-11, Wenhua Road, Heping District, Shenyang, Liaoning Province (China); Li, Chuantong, E-mail: L272395355@163.com [School of Material Science and Technology, Lanzhou University of Technology, Langongping Road, Lanzhou 730050, Gansu Province (China); Yao, Xiayan, E-mail: 18215142756@163.com [School of Material Science and Technology, Lanzhou University of Technology, Langongping Road, Lanzhou 730050, Gansu Province (China)

    2016-04-30

    Graphical abstract: - Highlights: • The synthetic method of N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs was explored. • Amino and thiol groups were grafted on the surface of Fe{sub 3}O{sub 4}/o-MWCNTs. • The maximum adsorption capacity of N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs for lead was 199.6 mg/g. • The adsorption kinetics can be best described by pseudo-second order kinetics. - Abstract: The novel functionalization of multi-walled carbon nanotubes (MWCNTs) was synthesized by reacting trimethoxysilylpropanethiol (MPTs), hydrazine, ammonium ferrous sulfate, and ammonium ferric sulfate in sequence as efficient ways to introduce Fe{sub 3}O{sub 4}, amino and thiol groups onto the nanotubes sidewalls. The magnetic MWCNTs composite material (N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs) was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, x-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy and magnetization curve. The results revealed that MPTs and hydrazine were coated on the surface of N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs. A series of batch adsorption experiments were conducted to study the experimental conditions, such as pH, contact time, initial concentrations and temperatures, which affected the adsorption process. The adsorption experiment results showed that the maximum equilibrium adsorption capacity of N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs for lead, zinc and phenol was 195.81 mg/g, 169.89 mg/g and 38.97 mg/g at pH 6, respectively. The adsorption isotherm was better fitted by the Freundlich model, and the adsorption kinetics was consistent with pseudo-second order kinetics model. Furthermore, thermodynamic data showed that the adsorption process was spontaneous and exothermic. These results indicated that N{sub 2}H{sub 4}–SH–Fe{sub 3}O{sub 4}/o-MWCNTs may be promising surface

  5. A Tunable Carbon Nanotube Oscillator

    Science.gov (United States)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  6. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  7. Hydrogen Storage in Carbon Nanotubes

    Science.gov (United States)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd

    2004-10-01

    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  8. Glucose oxidase immobilization onto carbon nanotube networking

    CERN Document Server

    Karachevtsev, V A; Zarudnev, E S; Karachevtsev, M V; Leontiev, V S; Linnik, A S; Lytvyn, O S; Plokhotnichenko, A M; Stepanian, S G

    2012-01-01

    When elaborating the biosensor based on single-walled carbon nanotubes (SWNTs), it is necessary to solve such an important problem as the immobilization of a target biomolecule on the nanotube surface. In this work, the enzyme (glucose oxidase (GOX)) was immobilized on the surface of a nanotube network, which was created by the deposition of nanotubes from their solution in 1,2-dichlorobenzene by the spray method. 1-Pyrenebutanoic acid succinimide ester (PSE) was used to form the molecular interface, the bifunctional molecule of which provides the covalent binding with the enzyme shell, and its other part (pyrene) is adsorbed onto the nanotube surface. First, the usage of such a molecular interface leaves out the direct adsorption of the enzyme (in this case, its activity decreases) onto the nanotube surface, and, second, it ensures the enzyme localization near the nanotube. The comparison of the resonance Raman (RR) spectrum of pristine nanotubes with their spectrum in the PSE environment evidences the creat...

  9. Polymer Self-assembly on Carbon Nanotubes

    Science.gov (United States)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  10. Suspended carbon nanotubes coupled to superconducting circuits

    NARCIS (Netherlands)

    Schneider, B.H.

    2014-01-01

    Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which i

  11. Carbon Nanotubes – Interactions with Biological Systems

    OpenAIRE

    Reis, Joana; Capela-Silva, Fernando; Potes, José; Fonseca, Alexandra; Oliveira, Mónica; Kanagaraj, Subramani; Marques, António Torres

    2011-01-01

    his book chapter discusses the prospective biomedical applications of carbon nanotubes based materials, the impact of carbon nanotubes properties in the interaction with biological systems. Protein adsorption, impact on cell viability and cytokine production are explored. Potential respiratory and dermal toxicity are reviewed, as the difficulties on studying the biological response. In face of recent studies, special attention is drawn upon promising orthopaedic use.

  12. Multiscale Simulations of Carbon Nanotubes and Liquids

    Science.gov (United States)

    Koumoutsakos, Petros

    2005-11-01

    We present molecular dynamics and hybrid continuum/atomistic simulations of carbon nanotubes in liquid environments with an emphasis on aqueous solutions. We emphasize computational issues such as interaction potentials and coupling techniques and their influence on the simulated physics. We present results from simulations of water flows inside and outside doped and pure carbon nanotubes and discuss their implications for experimental studies.

  13. An amperometric biosensor based on acetylcholinesterase immobilized onto iron oxide nanoparticles/multi-walled carbon nanotubes modified gold electrode for measurement of organophosphorus insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Nidhi [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India); Pundir, Chandra Shekhar, E-mail: pundircs@rediffmail.com [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India)

    2011-09-02

    Graphical abstract: The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution. Highlights: {center_dot} Constructed a novel composite material using Fe{sub 3}O{sub 4}NP and c-MWCNT at Au electrode for electrocatalysis. {center_dot} The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. {center_dot} The biosensor exhibited good sensitivity (0.475 mA {mu}M{sup -1}) {center_dot} The half life of electrode was 2 months. {center_dot} The sensor was suitable for trace detection of OP pesticide residues in milk and water. - Abstract: An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe{sub 3}O{sub 4}NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe{sub 3}O{sub 4}/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe{sub 3}O{sub 4}NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4 V). The optimum working conditions for the sensor were pH 7.5, 35 deg. C, 600 {mu}M substrate concentration and 10 min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40 nM, 0.1-50 nM, 1-50 nM and 10-100 nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1 nM for malathion and chlorpyrifos, 1 nM for monocrotophos and 10 nM for endosulfan. The

  14. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2.xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2.xH2O in the composite electrodes reaches 75%. In addition, supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  15. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    马仁志; 魏秉庆; 徐才录; 梁吉; 吴德海

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2 ·xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2· xH2O in the composite electrodes reaches 75% . In addition , supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  16. Reinforcing effect of plasma modified halloysite nanotubes in a carbon black filled natural rubber-butadien rubber matrix

    NARCIS (Netherlands)

    Poikelispaa, Minna; Das, Amit; Dierkes, Wilma; Vuorinen, Jyrki

    2011-01-01

    Rubber composites are generally produced by the direct incorporation of fillers like carbon black and/or silica into the rubber matrix. The incorporation of different types of nanofillers is the subject of recent research with the aim of preparing composites with special compositions and properties.

  17. Epitaxial Approaches to Carbon Nanotube Organization

    Science.gov (United States)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  18. Growing carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Yoshinori Ando

    2004-10-01

    Full Text Available The discovery of ‘fullerenes’ added a new dimension to the knowledge of carbon science1; and the subsequent discovery of ‘carbon nanotubes’ (CNTs, the elongated fullerene added a new dimension to the knowledge of technology2;. Today, ‘nanotechnology’ is a hot topic attracting scientists, industrialists, journalists, governments, and even the general public. Nanotechnology is the creation of functional materials, devices, and systems through control of matter on the nanometer scale and the exploitation of novel phenomena and properties of matter (physical, chemical, biological, electrical, etc. at that length scale. CNTs are supposed to be a key component of nanotechnology. Almost every week a new potential application of CNTs is identified, stimulating scientists to peep into this tiny tube with ever increasing curiosity.

  19. Molecular Dynamics Simulations of Carbon Nanotubes in Water

    Science.gov (United States)

    Walther, J. H.; Jaffe, R.; Halicioglu, T.; Koumoutsakos, P.

    2000-01-01

    We study the hydrophobic/hydrophilic behavior of carbon nanotubes using molecular dynamics simulations. The energetics of the carbon-water interface are mainly dispersive but in the present study augmented with a carbon quadrupole term acting on the charge sites of the water. The simulations indicate that this contribution is negligible in terms of modifying the structural properties of water at the interface. Simulations of two carbon nanotubes in water display a wetting and drying of the interface between the nanotubes depending on their initial spacing. Thus, initial tube spacings of 7 and 8 A resulted in a drying of the interface whereas spacing of > 9 A remain wet during the course of the simulation. Finally, we present a novel particle-particle-particle-mesh algorithm for long range potentials which allows for general (curvilinear) meshes and "black-box" fast solvers by adopting an influence matrix technique.

  20. Iron nanoparticles decorated multi-wall carbon nanotubes modified carbon paste electrode as an electrochemical sensor for the simultaneous determination of uric acid in the presence of ascorbic acid, dopamine and L-tyrosine.

    Science.gov (United States)

    Bhakta, Arvind K; Mascarenhas, Ronald J; D'Souza, Ozma J; Satpati, Ashis K; Detriche, Simon; Mekhalif, Zineb; Dalhalle, Joseph

    2015-12-01

    Iron nanoparticles decorated multi-wall carbon nanotubes modified carbon paste electrode (Fe-MWCNTs/MCPE) was prepared by bulk-modification method. The electrochemical impedance spectroscopy (EIS) suggests least charge transfer resistance at the modified electrode. The electrochemical behavior of UA was studied in 0.1M phosphate buffer solution (PBS) of pH3.0 using cyclic voltammetry (CV) while differential pulse voltammetry (DPV) was used for quantification. The spectroelectrochemial study of oxidation of UA at Fe-MWCNTs/MCPE showed a decrease in the absorbance of two peaks with time, which are ascribed to π to π(⁎) and n to π(⁎) transitions. Under optimum condition, the DPV response offered two linear dynamic ranges for UA in the concentration range 7.0×10(-8)M-1.0×10(-6)M and 2.0×10(-6)M-1.0×10(-5)M with detection limit (4.80±0.35)×10(-8)M (S/N=3). The practical analytical application of this sensor was successfully evaluated by determination of spiked UA in clinical samples, such as human blood serum and urine with good percentage recovery. The proposed electrochemical sensor offers a simple, reliable, rapid, reproducible and cost effective analysis of a quaternary mixture of biomolecules containing AA, DA, UA and Tyr which was free from mutual interferences.

  1. Electrochemically selective determination of dopamine in the presence of ascorbic and uric acids on the surface of the modified Nafion/single wall carbon nanotube/poly(3-methylthiophene) glassy carbon electrodes.

    Science.gov (United States)

    Quan, Do Phuc; Tuyen, Do Phuc; Lam, Tran Dai; Tram, Phan Thi Ngoc; Binh, Nguyen Hai; Viet, Pham Hung

    2011-12-01

    A voltammetric method based on a combination of incorporated Nafion, single-walled carbon nanotubes and poly(3-methylthiophene) film-modified glassy carbon electrode (NF/SWCNT/PMT/GCE) has been successfully developed for selective determination of dopamine (DA) in the ternary mixture of dopamine, ascorbic acid (AA) and uric acid (UA) in 0.1M phosphate buffer solution (PBS) pH 4. It was shown that to detect DA from binary DA-AA mixture, the use of NF/PMT/GCE was sufficient, but to detect DA from ternary DA-AA-UA mixture NF/SWCNT/PMT/GCE was required. The later modified electrode exhibits superior electrocatalytic activity towards AA, DA and UA thanks to synergic effect of NF/SWCNT (combining unique properties of SWCNT such as high specific surface area, electrocatalytic and adsorptive properties, with the cation selectivity of NF). On the surface of NF/SWCNT/PMT/GCE AA, DA, UA were oxidized respectively at distinguishable potentials of 0.15, 0.37 and 0.53 V (vs. Ag/AgCl), to form well-defined and sharp peaks, making possible simultaneous determination of each compound. Also, it has several advantages, such as simple preparation method, high sensitivity, low detection limit and excellent reproducibility. Thus, the proposed NF/SWCNT/PMT/GCE could be advantageously employed for the determination of DA in real pharmaceutical formulations.

  2. Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes

    Indian Academy of Sciences (India)

    F L Deepak; A Govindaraj; C N R Rao

    2006-01-01

    Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Yjunction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallicthiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon nanotubes with Y-junctions. Pyrolysis of organometallic-hydrocarbon mixtures, in the absence of water vapour, only gives nanotubes with T- and Y-junctions.

  3. Carbon nanotube growth density control

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  4. Purification of carbon nanotube by wet oxidation; Shisshiki sanka ni yoru carbon nanotube no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, K.; Takarada, T. [Gunma University, Gunma (Japan)

    1997-07-10

    In order to efficiently recover carbon nanotubes, the purification method by wet oxidation with orthoperiodic acid and perchloric acid is investigated. The reactivity of the carbonaceous material toward the acids depends on the type of carbon. Carbon nanotubes are selectively recovered under the mild oxidation conditions. The degree of purification depends on the concentration of orthoperiodic acid. It is suggested that wet oxidation is an effective method for purification of carbon nanotubes. 17 refs., 6 figs.

  5. Effect of chemical potential on the computer simulation of hydrogen storage in single walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Hong; WANG; Shaoqing; CHENG; Huiming

    2004-01-01

    Grand canonical Monte Carlo molecular simulations were carried out for hydrogen adsorption in single-walled carbon nanotubes. It was found that variations in chemical potential may result in a great change in the hydrogen storage capacity of single-walled carbon nanotubes. Hydrogen adsorption isotherms of single-walled carbon nanotubes at 298.15 K were calculated using a modified chemical potential, and the result obtained is closer to the experimental results. By comparing the experimental and simulation results, it is proposed that chemical adsorption may exist for hydrogen adsorption in single-walled carbon nanotubes.

  6. On the structural and mechanical properties of Fe-filled carbon nanotubes: a computer simulation approach.

    Science.gov (United States)

    Soldano, G; Mariscal, M M

    2009-04-22

    The structural and mechanical properties of single-and multi-walled carbon nanotubes filled with iron nanowires are studied using a recent parameterization of the modified embedded atom model. We have analyzed the effect of different crystal structures of iron (bcc and fcc) inside carbon nanotubes of different topographies. We have computed strain energy versus strain curves for pure systems: Fe nanowires, carbon and Fe-filled carbon nanotubes. A noticeable difference is found when these monatomic systems are joined to form iron-capped nanowires and where multi-layers of graphite are added to the nanotubes.

  7. Ambient effects on the electrical conductivity of carbon nanotubes

    DEFF Research Database (Denmark)

    Roch, Aljoscha; Greifzu, Moritz; Roch Talens, Esther

    2015-01-01

    We show that the electrical conductivity of single walled carbon nanotubes (SWCNT) networks is affected by oxygen and air humidity under ambient conditions by more than a magnitude. Later, we intentionally modified the electrical conductivity by functionalization with iodine and investigated...

  8. Electrochemiluminescent Properties of Organic Films with Incorporated Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yu.T. Zholudov

    2012-06-01

    Full Text Available This work describes the study of the electrochemical and electrochemiluminescent properties of electrodes modified by films of polyvinyl alcohol containing luminophor tris-bipyridine ruthenium and carbon nanotubes. Studied electrode structures showed good applicability for the development of nanotechnological ECL-sensors intended for the assay in aqueous mediums.

  9. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    NARCIS (Netherlands)

    Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

  10. On the elastic properties of carbon nanotube-based composites: modelling and characterization

    CERN Document Server

    Thostenson, E T

    2003-01-01

    The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon nanotube strongly influences the overall properties of the composite. The focus of this research is to develop a fundamental understanding of the structure/size influence of carbon nanotubes on the elastic properties of nanotube-based composites. Towards this end, the nanoscale structure and elastic properties of a model composite system of aligned multi-walled carbon nanotubes embedded in a polystyrene matrix were characterized, and a micromechanical approach for modelling of short fibre composites was modified to account for the structure of the nanotube reinforcement to predict the elastic modulus of the nanocomposite as a function of the constituent properties, reinforcement geometry and nanot...

  11. Modifications of multi-wall carbon nanotubes with B-containing vapor and their effects on the properties of boron carbide matrix nanocomposites.

    Science.gov (United States)

    Herth, S; Miranda, D; Doremus, R H; Siegel, R W

    2008-06-01

    Multi-wall carbon nanotubes were modified by heating them together with elemental boron powder. B4C crystals grew on the surfaces of the nanotubes, and electron diffraction patterns showed an orientation dependence of the surface B4C and the underlying carbon in the nanotubes. There was no reaction of the nanotubes with solid B2O3 alone. Composites of the modified nanotubes in a B4C matrix showed a small increase of density over sintered B4C.

  12. Functionalized carbon nanotubes: biomedical applications

    Directory of Open Access Journals (Sweden)

    Vardharajula S

    2012-10-01

    Full Text Available Sandhya Vardharajula,1 Sk Z Ali,2 Pooja M Tiwari,1 Erdal Eroğlu,1 Komal Vig,1 Vida A Dennis,1 Shree R Singh11Center for NanoBiotechnology and Life Sciences Research, Alabama State University, Montgomery, AL, USA; 2Department of Microbiology, Osmania University, Hyderabad, IndiaAbstract: Carbon nanotubes (CNTs are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity.Keywords: carbon nanotubes, cytotoxicity, functionalization, biomedical applications

  13. Selective intercalation of polymers in carbon nanotubes.

    Science.gov (United States)

    Bazilevsky, Alexander V; Sun, Kexia; Yarin, Alexander L; Megaridis, Constantine M

    2007-07-03

    A room-temperature, open-air method is devised to selectively intercalate relatively low-molecular-weight polymers (approximately 10-100 kDa) from dilute, volatile solutions into open-end, as-grown, wettable carbon nanotubes with 50-100 nm diameters. The method relies on a novel self-sustained diffusion mechanism driving polymers from dilute volatile solutions into carbon nanotubes and concentrating them there. Relatively low-molecular-weight polymers, such as poly(ethylene oxide) (PEO, 600 kDa) and poly(caprolactone) (PCL, 80 kDa), were encapsulated in graphitic nanotubes as confirmed by transmission electron microscopy, which revealed morphologies characteristic of mixtures in nanoconfinements affected by intermolecular forces. Whereas relatively small, flexible polymer molecules can conform to enter these nanotubes, larger macromolecules (approximately 1000 kDa) remain outside. The selective nature of this process is useful for filling nanotubes with polymers and could also be valuable in capping nanotubes.

  14. SYNTHESIS OF CARBON NANOTUBES FOR ACETYLENE DETECTION

    Directory of Open Access Journals (Sweden)

    M.Y. FAIZAH

    2008-04-01

    Full Text Available A gas sensor, utilizing carbon nanotubes (CNTs in a pellet form for acetylene detection has been developed. This research was carried out to investigate the absorption effect of acetylene (C2H2 towards the change of resistance of carbon nanotubes pellet as sensor signal. Source Measurement Unit (SMU was used to study the gas sensing behaviour of resistance based sensors employing carbon nanotubes pellet as the active sensing element. Studies revealed that the absorption of acetylene into the carbon nanotubes pellet resulting in increase in pellet resistance. The changes are attributed to p-type conductivity in semiconducting carbon nanotubes. Carbon nanotubes used in this research was synthesized by means of Floating Catalyst Chemical Vapor Deposition (FC-CVD method. Benzene was used as a hydrocarbon source while ferrocene as a source of catalyst with Hydrogen and Argon as carrier and purge gas respectively. From the research, it was shown that carbon nanotubes show high sensitivity towards acetylene. The highest sensitivity recorded was 1.21, 1.16 and 17.86 for S1, S2 and S3 respectively. It is expected that many applications of CNT-based sensors will be explored in future as the interest of the nanotechnology research in this field increases.

  15. A Tester for Carbon Nanotube Mode Lockers

    Science.gov (United States)

    Song, Yong-Won; Yamashita, Shinji

    2007-05-01

    We propose and demonstrate a tester for laser pulsating operation of carbon nanotubes employing a circulator with the extra degree of freedom of the second port to access diversified nanotube samples. The nanotubes are deposited onto the end facet of a dummy optical fiber by spray method that guarantees simple sample loading along with the minimized perturbation of optimized laser cavity condition. Resultant optical spectra, autocorrelation traces and pulse train of the laser outputs with qualified samples are presented.

  16. Prismatic modifications of single-walled carbon nanotubes and their electronic properties: Regular adsorption of fluorine atoms on graphene surfaces of nanotubes

    Science.gov (United States)

    Tomilin, O. B.; Stankevich, I. V.; Muryumin, E. E.; Lesin, S. A.; Syrkina, N. P.

    2011-01-01

    The regular adsorption of fluorine atoms on surfaces of single-walled carbon nanotubes along their axes can lead to a modification of cylindrical carbon cores of these single-walled carbon nanotubes to carbon cores that have a nearly prismatic shape (prismatic modification). In faces of these modified single-walled carbon nanotubes, there can arise quasi-one-dimensional isolated carbon conjugated subsystems (tracks) with different structures. It has been established that the main characteristics of the single-walled carbon nanotubes thus modified are rather close to the corresponding characteristics of the related isostructural polymer conjugated systems (such as cis-polyenes, polyphenylenes, poly(periacenes), or polyphenantrenes). Fragments of model nanotubes of the ( n, n) and ( n, 0) types that contain up to 360 carbon atoms and their derivatives doped with fluorine atoms have been calculated using the semiempirical parametric method 3.

  17. Enzymatic degradation of multiwalled carbon nanotubes.

    Science.gov (United States)

    Zhao, Yong; Allen, Brett L; Star, Alexander

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes.

  18. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  19. Methods for producing reinforced carbon nanotubes

    Science.gov (United States)

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  20. Ordered phases of cesium in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jeong Won; Hwang, Ho Jung; Song, Ki Oh; Choi, Won Young; Byun, Ki Ryang [Chung-Ang University, Seoul (Korea, Republic of); Kwon, Oh Keun [Semyung University, Jecheon (Korea, Republic of); Lee, Jun Ha [Sangmyung University, Chonan (Korea, Republic of); Kim, Won Woo [Juseong College, Cheongwon (Korea, Republic of)

    2003-10-15

    We investigate the structural phases of Cs in carbon nanotubes by using a structural optimization process applied to an atomistic simulation method. As the radius of the carbon nanotubes is increased, the structures are found in various phases from an atomic strand to multishell packs composed of coaxial cylindrical shells. Both helical structures and layered structures are found. The numbers of helical atom rows composed of coaxial tubes and the orthogonal vectors of the circular rolling of a triangular network can explain the structural phases of Cs in carbon nanotubes.

  1. Microcapsule carbon nanotube devices for therapeutic applications

    Science.gov (United States)

    Kulamarva, Arun; Raja, Pavan M. V.; Bhathena, Jasmine; Chen, Hongmei; Talapatra, Saikat; Ajayan, Pulickel M.; Nalamasu, Omkaram; Prakash, Satya

    2009-01-01

    Carbon nanotubes are a new class of nanomaterials that have immense potential in the field of biomedicine. Their ability to carry large quantities of therapeutic molecules makes them prime candidates for providing targeted delivery of therapeutics for use in various diseases. However, their utility is limited due to the problems faced during their delivery to target sites. This article for the first time describes the design of a novel microcapsule carbon nanotube targeted delivery device. This device has potential in the targeted delivery of carbon nanotubes in suitable membranes along with their cargo, safely and effectively to the target loci.

  2. Highly oriented carbon nanotube papers made of aligned carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ding; Song Pengcheng; Liu Changhong; Wu Wei; Fan Shoushan [Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: chliu@tsinghua.edu.cn

    2008-02-20

    Paper-like carbon nanotube (CNT) materials have many important applications such as in catalysts, in filtration, actuators, capacitor or battery electrodes, and so on. Up to now, the most popular way of preparing buckypapers has involved the procedures of dispersion and filtration of a suspension of CNTs. In this work, we present a simple and effective macroscopic manipulation of aligned CNT arrays called 'domino pushing' in the preparation of the aligned thick buckypapers with large areas. This simple method can efficiently ensure that most of the CNTs are well aligned tightly in the buckypaper. The initial measurements indicate that these buckypapers have better performance on thermal and electrical conductance. These buckypapers with controllable structure also have many potential applications, including supercapacitor electrodes.

  3. The electrical conduction variation in stained carbon nanotubes

    Science.gov (United States)

    Sun, Shih-Jye; Wei Fan, Jun; Lin, Chung-Yi

    2012-01-01

    Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

  4. Methods for preparation of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rakov, Eduard G [D.I. Mendeleev Russian University of Chemical Technology, Moscow (Russian Federation)

    2000-01-31

    The most important methods of synthesis and purification of carbon nanotubes, a new form of material, are described. The prospects for increasing the scale of preparation processes and for more extensive application of nanotubes are evaluated. The bibliography includes 282 references.

  5. Carbon nanotubes for RF and microwaves

    OpenAIRE

    Burke, P. J.; Yu, Z; Rutherglen, C.

    2005-01-01

    In this invited overview paper we provide a brief up-to-date summary of the potential applications of carbon nanotubes for RF and microwave devices and systems. We focus in particular on the use of nanotubes as ultra-high speed interconnects in integrated circuits.

  6. Carbon nanotubes as heat dissipaters in microelectronics

    DEFF Research Database (Denmark)

    Pérez Paz, Alejandro; García-Lastra, Juan María; Markussen, Troels

    2013-01-01

    We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties...

  7. Carbon Nanotubes for Human Space Flight

    Science.gov (United States)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  8. Formation of a robust and stable film comprising ionic liquid and polyoxometalate on glassy carbon electrode modified with multiwalled carbon nanotubes: Toward sensitive and fast detection of hydrogen peroxide and iodate

    Energy Technology Data Exchange (ETDEWEB)

    Haghighi, Behzad, E-mail: haghighi@iasbs.ac.i [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195 - 1159, Gava Zang, Zanjan (Iran, Islamic Republic of); Hamidi, Hassan [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195 - 1159, Gava Zang, Zanjan (Iran, Islamic Republic of); Gorton, Lo [Institute of Chemistry, Lund University, P.O. Box 124, S-221 00 Lund (Sweden)

    2010-06-30

    A robust and stable film comprising n-octylpyridinum hexafluorophosphate ([C{sub 8}Py][PF{sub 6}]) and 1:12 phosphomolybdic acid (PMo{sub 12}) was prepared on glassy carbon electrodes modified with multiwall carbon nanotubes (GCE/MWCNTs) by dip-coating. The cyclic voltammograms of the GCE/MWCNTs/[C{sub 8}Py][PF{sub 6}]-PMo{sub 12} showed three well-defined pairs of redox peaks due to the PMo{sub 12} system. The surface coverage for the immobilized PMo{sub 12} and the average values of the electron transfer rate constant for three pairs of redox peaks were evaluated. The GCE/MWCNTs/[C{sub 8}Py][PF{sub 6}]-PMo{sub 12} showed great electrocatalytic activity towards the reduction of H{sub 2}O{sub 2} and iodate. The kinetic parameters of the catalytic reduction of hydrogen peroxide and iodate at the electrode surface and analytical features of the sensor for amperometric determination of hydrogen peroxide and iodate were evaluated.

  9. Simultaneous voltammetric determination of dopamine and epinephrine in human body fluid samples using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film.

    Science.gov (United States)

    Figueiredo-Filho, Luiz C S; Silva, Tiago A; Vicentini, Fernando C; Fatibello-Filho, Orlando

    2014-06-07

    A simple and highly selective electrochemical method was developed for the single or simultaneous determination of dopamine (DA) and epinephrine (EP) in human body fluids using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film using square-wave voltammetry (SWV) or differential-pulse voltammetry (DPV). Using DPV with the proposed electrode, a separation of ca. 360 mV between the peak reduction potentials of DA and EP present in binary mixtures was obtained. The analytical curves for the simultaneous determination of dopamine and epinephrine showed an excellent linear response, ranging from 7.0 × 10(-8) to 4.8 × 10(-6) and 3.0 × 10(-7) to 9.5 × 10(-6) mol L(-1) for DA and EP, respectively. The detection limits for the simultaneous determination of DA and EP were 5.0 × 10(-8) mol L(-1) and 8.2 × 10(-8) mol L(-1), respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in human body fluid samples of cerebrospinal fluid, human serum and lung fluid.

  10. Poly-Alizarin red S/multiwalled carbon nanotube modified glassy carbon electrode for the boost up of electrocatalytic activity towards the investigation of dopamine and simultaneous resolution in the presence of 5-HT: A voltammetric study.

    Science.gov (United States)

    Reddaiah, K; Madhusudana Reddy, T; Venkata Ramana, D K; Subba Rao, Y

    2016-05-01

    Poly-Alizarin red S/multiwalled carbon nanotube film on the surface of glassy carbon electrode (poly-AzrS/MWCNT/GCE) was synthesized by electrochemical process and was used for the sensitive and selective determination of dopamine (DA) by employing voltammetric techniques. The electrocatalytic response of the modified electrode was found to exhibit admirable activity. The simultaneous determination of dopamine in the presence of serotonin (5-HT) was found to exhibit very good response at poly-AzrS/MWCNTs/GCE. The effect of pH, scan rate, accumulation time and concentration of dopamine was studied at the developed poly-AzrS/MWCNTs/GCE. The poly-AzrS/MWCNTs/GCE exhibited an efficient electron mediating behavior together with well resolved peaks for dopamine, in 0.1 mol/dm(3) phosphate buffer (PBS) solution of pH 7.0. The limit of detection (LOD) and limit of quantification (LOQ) were found to be as 1.89 × 10(-7) mol/dm(3) and 6.312 × 10(-7) mol/dm(3) respectively with a dynamic range from 1 × 10(-6) to 1.8 × 10(-5) mol/dm(3). The interfacial electron transfer behavior of DA was studied by electrochemical impedance spectroscopy (EIS); the studies showed that the charge transfer rate was enhanced at poly-AzrS/MWCNTs/GCE when compared with bare GCE and poly-AzrS/GCE.

  11. Molecular mechanics methods for individual carbon nanotubes and nanotube assemblies

    Science.gov (United States)

    Eberhardt, Oliver; Wallmersperger, Thomas

    2015-04-01

    Since many years, carbon nanotubes (CNTs) have been considered for a wide range of applications due to their outstanding mechanical properties. CNTs are tubular structures, showing a graphene like hexagonal lattice. Our interest in the calculation of the mechanical properties is motivated by several applications which demand the knowledge of the material behavior. One application in which the knowledge of the material behavior is vital is the CNT based fiber. Due to the excellent stiffness and strength of the individual CNTs, these fibers are expected to be a promising successor for state of the art carbon fibers. However, the mechanical properties of the fibers fall back behind the properties of individual CNTs. It is assumed that this gap in the properties is a result of the van-der-Waals interactions of the individual CNTs within the fiber. In order to understand the mechanical behavior of the fibers we apply a molecular mechanics approach. The mechanical properties of the individual CNTs are investigated by using a modified structural molecular mechanics approach. This is done by calculating the properties of a truss-beam element framework representing the CNT with the help of a chemical force field. Furthermore, we also investigate the interactions of CNTs arranged in basic CNT assemblies, mimicking the ones in a simple CNT fiber. We consider the van-der-Waals interactions in the structure and calculate the potential surface of the CNT assemblies.

  12. Coulomb drag in multiwall armchair carbon nanotubes

    DEFF Research Database (Denmark)

    Lunde, A.M.; Jauho, Antti-Pekka

    2004-01-01

    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  13. Flightweight Carbon Nanotube Magnet Technology

    Science.gov (United States)

    Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

    2003-01-01

    Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

  14. Purification of Carbon Nanotubes: Alternative Methods

    Science.gov (United States)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  15. Deconvoluting hepatic processing of carbon nanotubes

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  16. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    Science.gov (United States)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  17. Functionalized carbon nanotubes: biomedical applications.

    Science.gov (United States)

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R

    2012-01-01

    Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity.

  18. Carbon Nanotube Tape Vibrating Gyroscope

    Science.gov (United States)

    Tucker, Dennis Stephen (Inventor)

    2016-01-01

    A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

  19. Aligned carbon nanotubes for nanoelectronics

    Science.gov (United States)

    Choi, Won Bong; Bae, Eunju; Kang, Donghun; Chae, Soodoo; Cheong, Byung-ho; Ko, Ju-hye; Lee, Eungmin; Park, Wanjun

    2004-10-01

    We discuss the central issues to be addressed for realizing carbon nanotube (CNT) nanoelectronics. We focus on selective growth, electron energy bandgap engineering and device integration. We have introduced a nanotemplate to control the selective growth, length and diameter of CNTs. Vertically aligned CNTs are synthesized for developing a vertical CNT-field effect transistor (FET). The ohmic contact of the CNT/metal interface is formed by rapid thermal annealing. Diameter control, synthesis of Y-shaped CNTs and surface modification of CNTs open up the possibility for energy bandgap modulation. The concepts of an ultra-high density transistor based on the vertical-CNT array and a nonvolatile memory based on the top gate structure with an oxide-nitride-oxide charge trap are also presented. We suggest that the deposited memory film can be used for the quantum dot storage due to the localized electric field created by a nano scale CNT-electron channel.

  20. Carbon nanotubes – becoming clean

    Directory of Open Access Journals (Sweden)

    Nicole Grobert

    2007-01-01

    Full Text Available Carbon nanotubes (CNTs are now well into their teenage years. Early on, theoretical predictions and experimental data showed that CNTs possess chemical and mechanical properties that exceed those of many other materials. This has triggered intense research into CNTs. A variety of production methods for CNTs have been developed; chemical modification, functionalization, filling, and doping have been achieved; and manipulation, separation, and characterization of individual CNTs is now possible. Today, products containing CNTs range from tennis rackets and golf clubs to vehicle fenders, X-ray tubes, and Li ion batteries. Breakthroughs for CNT-based technologies are anticipated in the areas of nanoelectronics, biotechnology, and materials science. In this article, I review the current situation in CNT production and highlight the importance of clean CNT material for the success of future applications.

  1. Carbon nanotube polymer composition and devices

    Science.gov (United States)

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  2. Carbon nanotube heat-exchange systems

    Science.gov (United States)

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  3. A Thermal Model for Carbon Nanotube Interconnects

    Directory of Open Access Journals (Sweden)

    Clay Mayberry

    2013-04-01

    Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  4. Fabrication of porous carbon nanotube network.

    Science.gov (United States)

    Su, Jun-Wei; Fu, Shu-Juan; Gwo, Shangjr; Lin, Kuan-Jiuh; Lin, Kuna-Jiuh

    2008-11-21

    We used the spin-coating method combined with ultrasonic atomization as a continuous, one-step process to generate a two-dimensional honeycomb network that was constructed from pure multi-walled carbon nanotubes.

  5. Self Assembled Carbon Nanotube Enhanced Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to develop single wall carbon nanotube (SWCNT) based ultracapacitors for energy storage devices (ESD) application, using...

  6. Piezoresistive Sensors Based on Carbon Nanotube Films

    Institute of Scientific and Technical Information of China (English)

    L(U) Jian-wei; WANG Wan-lu; LIAO Ke-jun; WANG Yong-tian; LIU CHang-lin; Zeng Qing-gao

    2005-01-01

    Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test.Carbon nanotubes were synthesized by hot filament chemical vapor deposition.The experimental results showed that the carbon nanotubes have a striking piezoresistive effect.The relative resistance was changed from 0 to 10.5×10-2 and 3.25×10-2 for doped and undoped films respectively at room temperature when the microstrain under stress from 0 to 500. The gauge factors for doped and undoped carbon nanotube films under 500 microstrain were about 220 and 67 at room temperature, respectively, exceeding that of polycrystalline silicon (30) at 35℃.The origin of the resistance changes in the films may be attributed to a strain-induced change in the band gap for the doped tubes and the defects for the undoped tubes.

  7. Electrochemical Sensors Based on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Md. Aminur Rahman

    2009-03-01

    Full Text Available This review focuses on recent contributions in the development of the electrochemical sensors based on carbon nanotubes (CNTs. CNTs have unique mechanical and electronic properties, combined with chemical stability, and behave electrically as a metal or semiconductor, depending on their structure. For sensing applications, CNTs have many advantages such as small size with larger surface area, excellent electron transfer promoting ability when used as electrodes modifier in electrochemical reactions, and easy protein immobilization with retention of its activity for potential biosensors. CNTs play an important role in the performance of electrochemical biosensors, immunosensors, and DNA biosensors. Various methods have been developed for the design of sensors using CNTs in recent years. Herein we summarize the applications of CNTs in the construction of electrochemical sensors and biosensors along with other nanomaterials and conducting polymers.

  8. Carbon nanotube-based coatings on titanium

    Indian Academy of Sciences (India)

    Elzbieta Dlugon; Wojciech Simka; Aneta Fraczek-Szczypta; Wiktor Niemiec; Jaroslaw Markowski; Marzena Szymanska; Marta Blazewicz

    2015-09-01

    This paper reports results of the modification of titanium surface with multiwalled carbon nanotubes (CNTs). The Ti samples were covered with CNTs via electrophoretic deposition (EPD) process. Prior to EPD process, CNTs were functionalized by chemical treatment. Mechanical, electrochemical and biological properties of CNT-covered Ti samples were studied and compared to those obtained for unmodified titanium surface. Atomic force microscopy was used to investigate the surface topography. To determine micromechanical characteristics of CNT-covered metallic samples indentation tests were conducted. Throughout electrochemical studies were performed in order to characterize the impact of the coating on the corrosion of titanium substrate. In vitro experiments were conducted using the human osteoblast NHOst cell line. CNT layers shielded titanium from corrosion gave the surface-enhanced biointegrative properties. Cells proliferated better on the modified surface in comparison to unmodified titanium. The deposited layer enhanced cell adhesion and spreading as compared to titanium sample.

  9. Non-covalent interactions between carbon nanotubes and conjugated polymers.

    Science.gov (United States)

    Tuncel, Dönüs

    2011-09-01

    Carbon nanotubes (CNTs) are interest to many different disciplines including chemistry, physics, biology, material science and engineering because of their unique properties and potential applications in various areas spanning from optoelectronics to biotechnology. However, one of the drawbacks associated with these materials is their insolubility which limits their wide accessibility for many applications. Various approaches have been adopted to circumvent this problem including modification of carbon nanotube surfaces by non-covalent and covalent attachments of solubilizing groups. Covalent approach modification may alter the intrinsic properties of carbon nanotubes and, in turn make them undesirable for many applications. On the other hand, a non-covalent approach helps to improve the solubility of CNTs while preserving their intrinsic properties. Among many non-covalent modifiers of CNTs, conjugated polymers are receiving increasing attention and highly appealing because of a number of reasons. To this end, the aim of this feature article is to review the recent results on the conjugated polymer-based non-covalent functionalization of CNTs with an emphasis on the effect of conjugated polymers in the dispersibility/solubility, optical, thermal and mechanical properties of carbon nanotubes as well as their usage in the purification and isolation of a specific single-walled nanotube from the mixture of the various tubes.

  10. Controlled Deposition and Alignment of Carbon Nanotubes

    Science.gov (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  11. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-12-13

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  12. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-11-15

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  13. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-10-25

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  14. [Hygienic evaluation of multilayer carbon nanotubes].

    Science.gov (United States)

    Haliullin, T O; Zalyalov, R R; Shvedova, A A; Tkachov, A G

    2015-01-01

    The authors demonstrate that traditional methods evaluating work conditions on contemporary innovative enterprises producing nanomaterials assess these conditions as harmless and safe. At the same time, special investigation methods enable to reveal new hazards for workers' health: the study results prove that workers engaged into multilayer carbon nanotubes production are exposed to multilayer carbon nanotubes aerosols in concentrations exceeding internationally acceptable levels of 1 μg/ml (NIOSH)--that can harm the workers' health.

  15. Carbon nanotube temperature and pressure sensors

    Science.gov (United States)

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  16. Carbon nanotubes field effect transistors biosensors

    OpenAIRE

    Martínez, M.T.; Tseng, Y. C.; Ormategui, N.; Loinaz, I.; Eritja Casadellà, Ramón; Salvador, Juan Pablo; Marco, María Pilar; Bokor, J.

    2012-01-01

    [EN] Carbon nanotube transistor arrays (CNTFETs) were used as biosensors to detect NA hybridization and to recognize two anabolic steroids, stanozolol (Stz) and methylboldenone (MB). Single strand DNA and antibodies specific for STz and MB were immobilized on the carbon nanotubes (CNTs) in situ in the device using two different approaches: direct noncovalent bonding of antibodies to the devices and covalently trough a polymer previously attached to the CNTFETs. A new approach to ensure specif...

  17. The Effect of Functionalization Carbon Nanotubes (CNTs on the Performance of PES-CNTs Mixed Matrix Membrane

    Directory of Open Access Journals (Sweden)

    Ahmad Mustafa

    2010-07-01

    Full Text Available A new type of mixed matrix membrane consisting of functionalized carbon nanotubes (CNTs and polyethersulfone (PES is prepared for biogas purification. PES mixed matrix membrane with and without modification of carbon nanotubes were prepared by a dry/wet phase inversion technique using a pneumatically flat sheet membrane casting machine system. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using Dynasylan Ameo (DA silane agent to allow PES chains to be grafted on carbon nanotubes surface. The results from the FESEM, DSC and FTIR analysis confirmed that chemical modification on carbon nanotubes surface had taken place. Meanwhile, the nanogaps in the interface of polymer and carbon nanotubes were appeared in the PES mixed matrix membrane with unmodified of carbon nanotubes. The modified carbon nanotubes mixed matrix membrane increases the mechanical properties, the productivity and purity of biogas. For PES-modified carbon nanotubes mixed matrix membrane the maximum selectivity achieved for CO2/CH4 is 36.78

  18. An electrochemical sensor for rizatriptan benzoate determination using Fe{sub 3}O{sub 4} nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Madrakian, Tayyebeh, E-mail: madrakian@basu.ac.ir; Maleki, Somayeh; Heidari, Mozhgan; Afkhami, Abbas

    2016-06-01

    In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4}/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe{sub 3}O{sub 4} nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5–100.0 μmol L{sup −1} with a detection limit of 0.09 μmol L{sup −1} under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical. - Highlights: • Simple and sensitive Fe{sub 3}O{sub 4}/MWCNTs/GCE for rizatriptan benzoate determination • The surface morphology of nanocomposite was characterized by SEM and EDS. • Rizatriptan benzoate was measured at 0.09 μmol L{sup −1} with good sensitivity and selectivity. • The electrode has been successfully applied in serum and pharmaceutical samples. • The nanocomposite had excellent electrocatalytic activity and biocompatibility.

  19. Selective detection of dopamine in the presence of uric acid using a gold nanoparticles-poly(luminol) hybrid film and multi-walled carbon nanotubes with incorporated β-cyclodextrin modified glassy carbon electrode.

    Science.gov (United States)

    Jia, Dong; Dai, Jianyuan; Yuan, Hongyan; Lei, Ling; Xiao, Dan

    2011-10-15

    Gold nanoparticles-poly(luminol) (Plu-AuNPs) hybrid film and multi-walled carbon nanotubes with incorporated β-cyclodextrin modified glassy carbon electrode (β-CD-MWCNTs/Plu-AuNPs/GCE) was successfully prepared for simultaneous determination of dopamine (DA) and uric acid (UA). The surface of the modified electrode has been characterized by X-ray photo-electron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscope (SEM) and transmission electron microscope (TEM). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) have been used to investigate the β-CD-MWCNTs/Plu-AuNPs composite film. Gold nanoparticles anchored into poly(luminol) film exhibited catalytic activity for DA. MWCNTs with incorporated β-CD can greatly promote the direct electron transfer. In 0.10 M phosphate buffer solution (PBS, pH 7.0), the DPV response of the β-CD-MWCNTs/Plu-AuNPs/GCE sensor to DA is about 8-fold as compared with the Plu-AuNPs/GCE sensor, and the detection limit for DA is about one order of magnitude lower than the Plu-AuNPs/GCE sensor. The steady-state current response increases linearly with DA concentration from 1.0 × 10(-6) to 5.6 × 10(-5)M with a low detection limit (S/N=3) of 1.9 × 10(-7)M. Moreover, the interferences of ascorbic acid (AA) and uric acid (UA) are effectively diminished. The applicability of the prepared electrode has been demonstrated by measuring DA contents in dopamine hydrochloride injection.

  20. Filling of carbon nanotubes and nanofibres

    Directory of Open Access Journals (Sweden)

    Reece D. Gately

    2015-02-01

    Full Text Available The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications.

  1. ON THE CONTINUUM MODELING OF CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    张鹏; 黄永刚; Philippe H.Geubelle; 黄克智

    2002-01-01

    We have recently proposed a nanoscale continuum theory for carbonnanotubes. The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes directlyinto the constitutive law. Here we address two main issues involved in setting upthe nanoscale continuum theory for carbon nanotubes, namely the multi-body in-teratomic potentials and the lack of centrosymmetry in the nanotube structure. Weexplain the key ideas behind these issues in establishing a nanoscale continuum theoryin terms of interatomic potentials and atomic structures.

  2. Method for nano-pumping using carbon nanotubes

    Science.gov (United States)

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  3. Fast readout of carbon nanotube mechanical resonators

    Science.gov (United States)

    Meerwaldt, Harold; Singh, Vibhor; Schneider, Ben; Schouten, Raymond; van der Zant, Herre; Steele, Gary

    2013-03-01

    We perform fast readout measurements of carbon nanotube mechanical resonators. Using an electronic mixing scheme, we can detect the amplitude of the mechanical motion with an intermediate frequency (IF) of 46 MHz and a timeconstant of 1 us, up to 5 orders of magnitude faster than before. Previous measurements suffered from a low bandwidth due to the combination of the high resistance of the carbon nanotube and a large stray capacitance. We have increased the bandwidth significantly by using a high-impedance, close-proximity HEMT amplifier. The increased bandwidth should allow us to observe the nanotube's thermal motion and its transient response, approaching the regime of real-time detection of the carbon nanotube's mechanical motion.

  4. Manipulation and cutting of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nanomanipulation plays an important role in nanofabrication, it is also a technology necessary in exploring the secrets of nanoworld, and it thus beco mesa start point to research future nanomachine. In this study, manipulation and cutting of carbon nanotubes have been conducted in order to examine whether we can move a nanocomponent from one site to another by using the tip of atomic fo rce microscope (AFM). The technique may also be valuable for providing the const ructive materials of nanofabrication. While exploring the method for manipulatin g and cutting of nanotubes, some new phenomena have been observed during the process. Results show that carbon nanotubes present a feature of deformation combin ing bending and distortion when subjected to large mechanical forces exerted by the tip of AFM. In special cases, long carbon nanotubes can be cut into two part s, by which we can remove the part where crystal lattice is flawed, and therefor e a perfect nanocomponent can be obtained.

  5. Static and dynamic wetting measurements of single carbon nanotubes.

    Science.gov (United States)

    Barber, Asa H; Cohen, Sidney R; Wagner, H Daniel

    2004-05-07

    Individual carbon nanotubes were immersed and removed from various organic liquids using atomic force microscopy. The carbon nanotube-liquid interactions could be monitored in situ, and accurate measurements of the contact angle between liquids and the nanotube surface were made. These wetting data were used to produce Owens and Wendt plots giving the dispersive and polar components of the nanotube surface.

  6. A Study of Surface Modifications of Carbon Nanotubes on the Properties of Polyamide 66/Multiwalled Carbon Nanotube Composites

    Directory of Open Access Journals (Sweden)

    Li Qiu

    2013-01-01

    Full Text Available The effects of surface modification of carbon nanotube on the properties of polyamide 66/multiwalled carbon nanotube composites have been investigated. Polyamide 66 (PA66 and multiwalled carbon nanotube (MWCNT composites were prepared by melt mixing. The surfaces of MWCNTs were modified with acid- and amine-groups. Field emission scanning electron microscopy analyses revealed that amine-MWCNTs (D-MWCNTs dispersed better in the PA66 matrix than pristine- and acid-MWCNTs. However, an introduction of D-MWCNTs into PA66 matrix induced heterogeneous nucleation and affected the crystal growth process during the crystallization of PA66/MWCNT composites. Both nanoindentation and friction analyses were carried out in a study of the effect of the introduction of modified MWCNTs on both mechanical and friction properties of the composites. With the introduction of D-MWCNTs, both nanohardness and elastic modulus of the composites were significantly improved, but it was observed that the maximum depth, nanohardness, and elastic modulus of the composites showed no distinct change before and after a friction test. It is evident that PA66/D-MWCNT composites have the least friction coefficient of the PA66/MWCNT composites of all the approaches of carbon nanotube surface modification.

  7. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  8. Application of aromatization catalyst in synthesis of carbon nanotubes

    Indian Academy of Sciences (India)

    Song Rongjun; Yang Yunpeng; Ji Qing; Li Bin

    2012-02-01

    In a typical chemical vapour deposition (CVD) process for synthesizing carbon nanotubes (CNTs), it was found that the aromatization catalysts could promote effectively the formation of CNT. The essence of this phenomenon was attributed to the fact that the aromatization catalyst can accelerate the dehydrogenation–cyclization and condensation reaction of carbon source, which belongs to a necessary step in the formation of CNTs. In this work, aromatization catalysts, H-beta zeolite, HZSM-5 zeolite and organically modified montmorillonite (OMMT) were chosen to investigate their effects on the formation of multi-walled carbon nanotubes (MWCNTs) via pyrolysis method when polypropylene and 1-hexene as carbon source and Ni2O3 as the charring catalyst. The results demonstrated that the combination of those aromatization catalysts with nickel catalyst can effectively improve the formation of MWCNTs.

  9. Oscillatory characteristics of carbon nanotubes inside carbon nanotube bundles

    Science.gov (United States)

    Ansari, R.; Alipour, A.; Sadeghi, F.

    2012-12-01

    This article presents a comprehensive study on the mechanics of carbon nanotubes (CNTs) oscillating in CNT bundles. Using the continuum approximation along with Lennard-Jones (LJ) potential function, new semi-analytical expressions in terms of double integrals are presented to evaluate van der Waals (vdW) potential energy and interaction force upon which the equation of motion is directly solved. The obtained potential expression enables one to arrive at a new semi-analytical formula for the exact evaluation of oscillation frequency. Also, an algebraic frequency formula is extracted on the basis of the simplifying assumption of constant vdW force. Based on the present expressions, a thorough study on various aspects of operating frequencies under different system parameters is given, which permits fresh insight into the problem. The strong dependence of oscillation frequency on system parameters, such as the extrusion distance and initial velocity of the core as initial conditions for the motion is indicated. Interestingly, a specific initial velocity is found at which the oscillation frequency is independent of the core length. In addition, a relation between this specific initial velocity and the escape velocity is disclosed.

  10. 75 FR 56880 - Multi-Walled Carbon Nanotubes and Single-Walled Carbon Nanotubes; Significant New Use Rules

    Science.gov (United States)

    2010-09-17

    ... structural characteristics entitled ``Material Characterization of Carbon Nanotubes for Molecular Identity... AGENCY 40 CFR Parts 9 and 721 RIN 2070-AB27 Multi-Walled Carbon Nanotubes and Single-Walled Carbon...). The two chemical substances are identified generically as multi-walled carbon nanotubes (MWCNT) (PMN...

  11. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes.

    Science.gov (United States)

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury

    2010-08-01

    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  12. Center for Applications of Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Resasco, Daniel E

    2008-02-21

    This report describes the activities conducted under a Congressional Direction project whose goal was to develop applications for Single-walled carbon nanotubes, under the Carbon Nanotube Technology Center (CANTEC), a multi-investigator program that capitalizes on OU’s advantageous position of having available high quality carbon nanotubes. During the first phase of CANTEC, 11 faculty members and their students from the College of Engineering developed applications for carbon nanotubes by applying their expertise in a number of areas: Catalysis, Reaction Engineering, Nanotube synthesis, Surfactants, Colloid Chemistry, Polymer Chemistry, Spectroscopy, Tissue Engineering, Biosensors, Biochemical Engineering, Cell Biology, Thermal Transport, Composite Materials, Protein synthesis and purification, Molecular Modeling, Computational Simulations. In particular, during this phase, the different research groups involved in CANTEC made advances in the tailoring of Single-Walled Carbon Nanotubes (SWNT) of controlled diameter and chirality by Modifying Reaction Conditions and the Nature of the catalyst; developed kinetic models that quantitatively describe the SWNT growth, created vertically oriented forests of SWNT by varying the density of metal nanoparticles catalyst particles, and developed novel nanostructured SWNT towers that exhibit superhydrophobic behavior. They also developed molecular simulations of the growth of Metal Nanoparticles on the surface of SWNT, which may have applications in the field of fuell cells. In the area of biomedical applications, CANTEC researchers fabricated SWNT Biosensors by a novel electrostatic layer-by-layer (LBL) deposition method, which may have an impact in the control of diabetes. They also functionalized SWNT with proteins that retained the protein’s biological activity and also retained the near-infrared light absorbance, which finds applications in the treatment of cancer.

  13. Carbon Nanotube-Based Synthetic Gecko Tapes

    Science.gov (United States)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  14. Highly sensitive and selective dopamine biosensor based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets/multi-wall carbon nanotubes/ionic liquid composite film modified electrode.

    Science.gov (United States)

    Niu, Xiuli; Yang, Wu; Guo, Hao; Ren, Jie; Gao, Jinzhang

    2013-03-15

    A sensitive and selective electrochemical sensor for determination of dopamine (DA) was fabricated based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets, multi-wall carbon nanotubes and ionic liquid modified glass carbon electrode and the properties of modified electrode were characterized by scanning electron microscopy, transmission electron microscope and electrochemical impedance spectroscopy. The modified electrode showed excellent electrocatalytic activity toward the oxidation of DA. Meanwhile, a possible reaction mechanism related to the oxidation of DA was proposed. The differential pulse voltammetry was used for the determination of DA in the presence of 500 μM ascorbic acid and 330 μM uric acid under the optimum conditions and a good linear relationship between peak current and the concentration of DA was obtained in the concentration range from 0.03 μM to 3.82 mM with a detection limit of 1.2×10(-9) M (S/N=3). Moreover, the proposed method was successfully applied to determine DA in real sample and satisfactory results were obtained. The results showed that the modified electrode exhibits an excellent catalytic activity, good sensitivity, reproducibility and long-term stability.

  15. A carbon nanotube wall membrane for water treatment.

    Science.gov (United States)

    Lee, Byeongho; Baek, Youngbin; Lee, Minwoo; Jeong, Dae Hong; Lee, Hong H; Yoon, Jeyong; Kim, Yong Hyup

    2015-05-14

    Various forms of carbon nanotubes have been utilized in water treatment applications. The unique characteristics of carbon nanotubes, however, have not been fully exploited for such applications. Here we exploit the characteristics and corresponding attributes of carbon nanotubes to develop a millimetre-thick ultrafiltration membrane that can provide a water permeability that approaches 30,000 l m(-2) h(-1) bar(-1), compared with the best water permeability of 2,400 l m(-2) h(-1) bar(-1) reported for carbon nanotube membranes. The developed membrane consists only of vertically aligned carbon nanotube walls that provide 6-nm-wide inner pores and 7-nm-wide outer pores that form between the walls of the carbon nanotubes when the carbon nanotube forest is densified. The experimental results reveal that the permeance increases as the pore size decreases. The carbon nanotube walls of the membrane are observed to impede bacterial adhesion and resist biofilm formation.

  16. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  17. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  18. Release characteristics of selected carbon nanotube polymer composites

    Science.gov (United States)

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  19. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    Science.gov (United States)

    Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

    2004-01-01

    This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

  20. Physical Removal of Metallic Carbon Nanotubes from Nanotube Network Devices Using a Thermal and Fluidic Process

    OpenAIRE

    Ford, Alexandra C.; Shaughnessy, Michael; Wong, Bryan M.; Kane, Alexander A.; Kuznetsov, Oleksandr V.; Krafcik, Karen L.; Billups, W. E.; Hauge, Robert H.; Léonard, François

    2013-01-01

    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is ...

  1. Poly-Alizarin red S/multiwalled carbon nanotube modified glassy carbon electrode for the boost up of electrocatalytic activity towards the investigation of dopamine and simultaneous resolution in the presence of 5-HT: A voltammetric study

    Energy Technology Data Exchange (ETDEWEB)

    Reddaiah, K. [Electrochemical Research Laboratory, Department of Chemistry, S.V.U. College of Sciences, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh (India); Madhusudana Reddy, T., E-mail: tmsreddysvu@gmail.com [Electrochemical Research Laboratory, Department of Chemistry, S.V.U. College of Sciences, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh (India); Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Venkata Ramana, D.K. [Department of Safety Engineering, Dongguk University, 123 Dongdae-ro, Gyeongju, Gyeongbuk 780 714 (Korea, Republic of); Subba Rao, Y. [DST-PURSE Centre, Sri Venkateswara University, Tirupati 517502, Andhra Pradesh (India)

    2016-05-01

    Poly-Alizarin red S/multiwalled carbon nanotube film on the surface of glassy carbon electrode (poly-AzrS/MWCNT/GCE) was synthesized by electrochemical process and was used for the sensitive and selective determination of dopamine (DA) by employing voltammetric techniques. The electrocatalytic response of the modified electrode was found to exhibit admirable activity. The simultaneous determination of dopamine in the presence of serotonin (5-HT) was found to exhibit very good response at poly-AzrS/MWCNTs/GCE. The effect of pH, scan rate, accumulation time and concentration of dopamine was studied at the developed poly-AzrS/MWCNTs/GCE. The poly-AzrS/MWCNTs/GCE exhibited an efficient electron mediating behavior together with well resolved peaks for dopamine, in 0.1 mol/dm{sup 3} phosphate buffer (PBS) solution of pH 7.0. The limit of detection (LOD) and limit of quantification (LOQ) were found to be as 1.89 × 10{sup −7} mol/dm{sup 3} and 6.312 × 10{sup −7} mol/dm{sup 3} respectively with a dynamic range from 1 × 10{sup −6} to 1.8 × 10{sup −5} mol/dm{sup 3}. The interfacial electron transfer behavior of DA was studied by electrochemical impedance spectroscopy (EIS); the studies showed that the charge transfer rate was enhanced at poly-AzrS/MWCNTs/GCE when compared with bare GCE and poly-AzrS/GCE. - Highlights: • The poly-AzrS/MWCNTs/GCE showed good sensitivity towards DA sensing. • The sensor reduced the overoxidation potentials for DA. • This electrode was successfully used for simultaneous sensing of DA and 5-HT. • The electrode was effectively used for the determination of DA in pharmaceutical formulations.

  2. Carbon Nanotube Tower-Based Supercapacitor

    Science.gov (United States)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  3. Carbon Nanotube-Based Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  4. Functionalized carbon nanotubes for potential medicinal applications.

    Science.gov (United States)

    Zhang, Yi; Bai, Yuhong; Yan, Bing

    2010-06-01

    Functionalized carbon nanotubes display unique properties that enable a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. High aspect ratio, unique optical property and the likeness as small molecule make carbon nanotubes an unusual allotrope of element carbon. After functionalization, carbon nanotubes display potentials for a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity.

  5. Carbon Nanotubes and Chronic Granulomatous Disease

    Directory of Open Access Journals (Sweden)

    Barbara P. Barna

    2014-06-01

    Full Text Available Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

  6. Elastomer Reinforced with Carbon Nanotubes

    Science.gov (United States)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  7. Localized Excitons in Carbon Nanotubes.

    Science.gov (United States)

    Adamska, Lyudmyla; Doorn, Stephen K.; Tretiak, Sergei

    2015-03-01

    It has been historically known that unintentional defects in carbon nanotubes (CNTs) may fully quench the fluorescence. However, some dopants may enhance the fluorescence by one order of magnitude thus turning the CNTs, which are excellent light absorbers, in good emitters. We have correlated the experimentally observed photoluminescence spectra to the electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50-300 meV red-shifted from that of the lowest bright exciton peak. Our simulations suggest an association of these peaks with deep trap states tied to different specific chemical adducts. While the wave functions of excitons in undoped CNTs are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with the experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from scattering of acoustic phonons on localized excitons. Our work lays the foundation to utilize doping as a generalized route for wave function engineering and direct control of carrier dynamics in SWCNTs toward enhanced light emission properties for photonic applications.

  8. Thermal Transport in Carbon Nanotubes

    Science.gov (United States)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  9. Different Technical Applications of Carbon Nanotubes.

    Science.gov (United States)

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  10. Chemical reactions confined within carbon nanotubes.

    Science.gov (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  11. Different Technical Applications of Carbon Nanotubes

    Science.gov (United States)

    Abdalla, S.; Al-Marzouki, F.; Al-Ghamdi, Ahmed A.; Abdel-Daiem, A.

    2015-09-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  12. Edge effects in finite elongated carbon nanotubes

    CERN Document Server

    Hod, O; Scuseria, G E; Hod, Oded; Peralta, Juan E.; Scuseria, Gustavo E.

    2006-01-01

    The importance of finite-size effects for the electronic structure of long zigzag and armchair carbon nanotubes is studied. We analyze the electronic structure of capped (6,6), (8,0), and (9,0) single walled carbon nanotubes as a function of their length up to 60 nm, using a divide and conquer density functional theory approach. For the metallic nanotubes studied, most of the physical features appearing in the density of states of an infinite carbon nanotube are recovered at a length of 40 nm. The (8,0) semi-conducting nanotube studied exhibits pronounced edge effects within the energy gap that scale as the inverse of the length of the nanotube. As a result, the energy gap reduces from the value of ~1 eV calculated for the periodic system to a value of ~0.25 eV calculated for a capped 62 nm long CNT. These edge effects are expected to become negligible only at tube lengths exceeding 6 micrometers. Our results indicate that careful tailoring of the nature of the system and its capping units should be applied w...

  13. Enhanced graphitization of carbon around carbon nanotubes during the formation of carbon nanotube/graphite composites by pyrolysis of carbon nanotube/polyaniline composites.

    Science.gov (United States)

    Nam, Dong Hoon; Cha, Seung Il; Jeong, Yong Jin; Hong, Soon Hyung

    2013-11-01

    The carbon nanotubes (CNTs) are actively applied to the reinforcements for composite materials during last decade. One of the attempts is development of CNT/Carbon composites. Although there are some reports on the enhancement of mechanical properties by addition of CNTs in carbon or carbon fiber, it is far below the expectation. Considering the microstructure of carbon materials such as carbon fiber, the properties of them can be modified and enhanced by control of graphitization and alignment of graphene planes. In this study, enhanced graphitization of carbon has been observed the vicinity of CNTs during the pyrolysis of CNT/Polyaniline composites. As a result, novel types of composite, consisting of treading CNTs and coated graphite, can be fabricated. High-resolution transmission electron microscopy revealed a specific orientation relationship between the graphene layers and the CNTs, with an angle of 110 degrees between the layers and the CNT axis. The possibility of graphene alignment control in the carbon by the addition of CNTs is demonstrated.

  14. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    Science.gov (United States)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  15. Chitosan-mediated synthesis of carbon nanotube-gold nanohybrids

    Institute of Scientific and Technical Information of China (English)

    GRAVEL; Edmond; FOILLARD; Stéphanie; DORIS; Eric

    2010-01-01

    Metal-nanotube nanohybrids were produced by in situ synthesis and stabilization of gold nanoparticles on chitosan-functionalized carbon nanotubes.The formation of gold nanoparticles from tetrachloroauric acid was observed after only a few minutes of contact with the functionalized nanotubes,at room temperature.These results suggest that adsorption of chitosan at the surface of carbon nanotubes permits smooth reduction of the metallic salt and efficient anchoring of gold nanoparticles to the nanotubes.

  16. Effects of single-walled carbon nanotubes on lysozyme gelation.

    Science.gov (United States)

    Tardani, Franco; La Mesa, Camillo

    2014-09-01

    The possibility to disperse carbon nanotubes in biocompatible matrices has got substantial interest from the scientific community. Along this research line, the inclusion of single walled carbon nanotubes in lysozyme-based hydrogels was investigated. Experiments were performed at different nanotube/lysozyme weight ratios. Carbon nanotubes were dispersed in protein solutions, in conditions suitable for thermal gelation. The state of the dispersions was determined before and after thermal treatment. Rheology, dynamic light scattering and different microscopies investigated the effect that carbon nanotubes exert on gelation. The gelation kinetics and changes in gelation temperature were determined. The effect of carbon and lysozyme content on the gel properties was, therefore, determined. At fixed lysozyme content, moderate amounts of carbon nanotubes do not disturb the properties of hydrogel composites. At moderately high volume fractions in carbon nanotubes, the gels become continuous in both lysozyme and nanotubes. This is because percolating networks are presumably formed. Support to the above statements comes by rheology.

  17. Deposition of the platinum crystals on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new technique and the affecting factors for depositing platinum on the carbon nanotubes were investigated. The results show that the deposited platinum crystals in the atmosphere of hydrogen or nitrogen have a small size and a homogeneous distribution on the surface of the carbon nanotubes. The pretreatment would decrease the platinum particles on the carbon nanotubes significantly.

  18. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  19. Interaction of pristine and functionalized carbon nanotubes with lipid membranes.

    Science.gov (United States)

    Baoukina, Svetlana; Monticelli, Luca; Tieleman, D Peter

    2013-10-10

    Carbon nanotubes are widely used in a growing number of applications. Their interactions with biological materials, cell membranes in particular, is of interest in applications including drug delivery and for understanding the toxicity of carbon nanotubes. We use extensive molecular dynamics simulations with the MARTINI model to study the interactions of model nanotubes of different thickness, length, and patterns of chemical modification with model membranes. In addition, we characterize the interactions of small bundles of carbon nanotubes with membrane models. Short pristine carbon nanotubes readily insert into membranes and adopt an orientation parallel to the plane of the membrane in the center of the membrane. Larger aggregates and functionalized nanotubes exhibit a range of possible interactions. The distribution and orientation of carbon nanotubes can be controlled by functionalizing the nanotubes. Free energy calculations provide thermodynamic insight into the preferred orientations of different nanotubes and quantify structural defects in the lipid matrix.

  20. Graphene-carbon nanotube hybrid materials and use as electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

    2016-09-27

    Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.