Use Of Single-walled Carbon Nanotubes Research Articles

Influence of single-walled carbon nanotubes on microbial availability of phenanthrene in sediment

Increasing production and use of single-walled carbon nanotubes (SWCNT) will inevitably lead to release of these nanoparticles to aquatic ecosystems. Similar to black carbon (BC) particles, SWCNT have a high affinity for hydrophobic organic contaminants (HOCs) and therefore the presence of SWCNT in sediment may lead to altered bioavailability of HOCs. We compared SWCNT with biochar and charcoal on their effect on the microbial degradability of 0.05 mg kg(-1) (14)C-phenanthrene (PHE) by Mycobacterium vanbaalenii PYR-1 in two sediments with different organic carbon (OC) contents. When the amendment rate of SWCNT or BC was 1 mg g(-1), PHE mineralization was inhibited much more significantly by SWCNT than by either biochar or charcoal. After 360 h of incubation, the mineralized fraction of PHE in the presence of SWCNT was 59.5% of the non-amended control in the sediment with low OC content, and only 42.4% in the other sediment with a higher OC content. Analysis of the freely dissolved concentration (C (free)) using disposable polydimethylsiloxane (PDMS) fibers showed that SWCNT decreased C (free) by 85-95%, apparently due to preferential sorption of PHE to SWCNT particles that had a much larger specific surface area and pore volume than biochar or charcoal. However, pre-interaction of SWCNT with dissolved organic matter (peptone, tannic acid, and humic acid) led to attachment of polar functional groups and reduced surface area on SWCNT, resulting in decreased PHE sorption and an alleviated effect on PHE biodegradation in the order of peptone > tannic acid > humic acid.

Quantum dynamics of hydrogen interacting with single-walled carbon nanotubes: Multiple H-atom adsorbates

In a previous paper [J. L. McAfee and B. Poirier, J. Chem. Phys. 130, 064701 (2009)], using spin-polarized density functional theory (DFT), the authors reported a binding energy of 0.755 eV, for a single hydrogen atom adsorbed on a pristine (unrelaxed) (5,5) single-walled carbon nanotube (SWNT) substrate. A full three-dimensional (3D) potential energy surface (PES) for the SWNT-H system was also developed, and used in a quantum dynamics calculation to compute all rovibrational bound states, and associated equatorial and longitudinal adsorbate migration rates. A highly pronounced preference for the latter migration pathway at ambient temperatures was observed. In this work, we extend the aforementioned study to include multiple H-atom adsorbates. Extensive DFT calculations are performed, in order to ascertain the most relevant dynamical pathways. For two adsorbates, the SWNT-H-H system is found to exhibit highly site-specific binding, as well as long-range correlation and pronounced binding energy enhancement. The latter effect is even more pronounced in the full-hydrogenation limit, increasing the per-adsorbate binding energy to 2.6 eV. To study migration dynamics, a single-hole model is developed, for which the binding energy drops to 2.11 eV. A global 3D PES is developed for the hole migration model, using 40 radial × 18 cylindrical ab initio geometries, fit to a Fourier basis with radially dependent expansion coefficients (rms error 4.9 meV). As compared with the single-adsorbate case, the hole migration PES does not exhibit separate chemisorption and physisorption wells. The barrier to longitudinal migration is also found to be much lower. Quantum dynamics calculations for all rovibrational states are then performed (using a mixed spectral basis/phase-space optimized discrete variable representation), and used to compute longitudinal migration rates. Ramifications for the use of SWNTs as potential hydrogen storage materials are discussed.

A drastic reduction in silver concentration of metallic ink by the use of single-walled carbon nanotubes decorated with silver nanoparticles

Download options Please wait... Supplementary files Supplementary information PDF (510K) Article information DOI https://doi.org/10.1039/C1JM10850F Article type Communication Submitted 26 Feb 2011 Accepted 28 Mar 2011 First published 11 Apr 2011 Download Citation J. Mater. Chem., 2011,21, 7070-7073 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions A drastic reduction in silver concentration of metallic ink by the use of single-walled carbon nanotubes decorated with silver nanoparticles R. Ma, D. Suh, J. Kim, J. Chung and S. Baik, J. Mater. Chem., 2011, 21, 7070 DOI: 10.1039/C1JM10850F To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Rujun Ma Daewoo Suh Joonghyuk Kim Jaewoo Chung Seunghyun Baik

Single-walled carbon nanotubes as optical materials for biosensing

In this review, we summarize recent progress in the development of single-walled carbon nanotubes (SWNTs) as optical materials for biosensing applications. First, as optical labels, we discuss the use of SWNTs in Raman-based protein detection. Strong and simple resonance Raman spectroscopy of SWNTs opens up a method of protein microarray with detection sensitivity down to femtomolar range. Also, tunable isotopic SWNT-Raman signature enables the simultaneous detection of multiple analytes in complex fluids. Second, the photoluminescence properties of SWNTs are also explored. We examine fluorescence biosensors that integrate the quenching property of SWNTs and the recognition property of functional nucleic acids. Particularly, SWNTs are established as an efficient signal transduction substrate in different biosensing systems, including the detection of specific proteins and DNA sequences, regulation of singlet oxygen generation and label-free fluorescence assays, and all have exhibited very high selectivity and sensitivity.

Enhanced cell uptake via non-covalent decollation of a single-walled carbon nanotube-DNA hybrid with polyethylene glycol-grafted poly(l-lysine) labeled with an Alexa-dye and its efficient uptake in a cancer cell

The use of single-walled carbon nanotubes (SWNTs) for biomedical applications is a promising approach due to their unique outer optical stimuli response properties, such as a photothermal response triggered by near-IR laser irradiation. The challenging task in order to realize such applications is to render the SWNTs biocompatible. For this purpose, the stable and homogeneous functionalization of the SWNTs with a molecule carrying a biocompatible group is very important. Here, we describe the design and synthesis of a polyanionic SWNT/DNA hybrid combined with a cationic poly(l-lysine) grafted by polyethylene glycol (PLL-g-PEG) to provide a supramolecular SWNT assembly. A titration experiment revealed that the assembly undergoes an approximately 1 : 1 reaction of the SWNT/DNA with PLL-g-PEG. We also found that SWNT/DNA is coated with PLL-g-PEG very homogeneously that avoids the non-specific binding of proteins on the SWNT surface. The experiment using the obtained supramolecular hybrid was carried out in vitro and a dramatic enhancement in the cell uptake efficiency compared to that of the SWNT/DNA hybrid without PLL-g-PEG was found.

New hybrid nanocomposites containing carbon nanotubes, inorganic fullerene-like WS2 nanoparticles and poly(ether ether ketone) (PEEK)

Single-walled carbon nanotubes (SWCNTs) and inorganic fullerene-like WS2 nanoparticles were successfully dispersed in poly(ether ether ketone) (PEEK) by advantageously traditional melt processing techniques. This strategy offers an attractive way to combine the merits of organic and inorganic materials into novel hybrid systems that challenge emerging polymer/CNT nanocomposites in terms of performance, cost and processability. In particular, the incorporation of IF-WS2 has shown to be efficient to produce well-dispersed PEEK/SWCNT composites influenced in turn by the processing method. The morphology, thermal stability, crystallization behaviour, thermal conductivity as well as mechanical and electrical properties of PEEK/SWCNT composites were tuneable by the introduction of small amounts of IF-WS2. The overall structural, thermal, mechanical and electrical performances confirm the potential use of SWCNTs and IF-WS2 for the preparation of advanced hybrid nanocomposites as lightweight alternatives for use in critical industrial applications of high-performance and high-temperature thermoplastics like PEEK.

Single-walled carbon nanotubes for improved enantioseparations on a chiral ionic liquid stationary phase in GC

In order to investigate whether the use of single-walled carbon nanotubes can improve enantioseparations on an ionic liquid stationary phase, a chiral ionic liquid, (R)-N,N,N-trimethyl-2-aminobutanol-bis(trifluoromethanesulfon)imidate, was synthesized. Two capillary columns, one containing the chiral ionic liquid and the other containing the single-walled carbon nanotubes and the chiral ionic liquid, were then prepared for GC. The results of the separations achieved with these columns show that coating the chiral ionic liquid stationary phase onto the capillary column containing single-walled carbon nanotubes improves the enantioselectivety of the chiral ionic liquid. This work indicates that using single-walled carbon nanotubes in this manner enables the application range of such GC chiral separations to be extended.

Separation of flavonoids and phenolic acids in complex natural products by microemulsion electrokinetic chromatography using surfactant‐coated and carboxylic single‐wall carbon nanotubes as additives

In this paper, we investigated the analytical potential of the use of single-walled carbon nanotubes (SWNTs) with different dispersion as additives in MEEKC. The addition of surfactant-coated single-walled carbon nanotubes (SC-SWNTs) in microemulsion provided a more efficient method than carboxylic SWNTs for the separation of three flavonoids and six phenolic acids depending on the interaction between the analytes and SWNTs surface. Additionally, the effect of important factors was examined by changing experimental variables such as the dispersion of SWNTs, surfactants and cosurfactants. Finally, the MEEKC method using SC-SWNTs was successfully applied to complex natural products (drug pair of Radix Astragali and Radix et Rhizoma Salvia Miltiorrhizae), with satisfactory results.

Pharmacological and toxicological target organelles and safe use of single-walled carbon nanotubes as drug carriers in treating Alzheimer disease

Identification of pharmacological and toxicological profiles is of critical importance for the use of nanoparticles as drug carriers in nanomedicine and for the biosafety evaluation of environmental nanoparticles in nanotoxicology. Here we show that lysosomes are the pharmacological target organelles for single-walled carbon nanotubes (SWCNTs) and that mitochondria are the target organelles for their cytotoxicity. The gastrointestinally absorbed SWCNTs were lysosomotropic but also entered mitochondria at large doses. Genes encoding phosphoinositide-3-kinase and lysosomal-associated membrane protein 2 were involved in such an organelle preference. SWCNT administration resulted in collapse of mitochondrial membrane potentials, giving rise to overproduction of reactive oxygen species, leading to damage of mitochondria, which was followed by lysosomal and cellular injury. Based on the dosage differences in target organelles, SWCNTs were successfully used to deliver acetylcholine into brain for treatment of experimentally induced Alzheimer disease with a moderate safety range by precisely controlling the doses, ensuring that SWCNTs preferentially enter lysosomes, the target organelles, and not mitochondria, the target organelles for SWCNT cytotoxicity. From the Clinical Editor Single wall carbon nanotubes (SWCNT) could make excellent targeted delivery systems for pharmaceuticals. Inside the cells, lysosomes are the pharmacological target organelles of SWCNT, but in large doses mitochondria also take up SWCNT and mitochondrial toxicity becomes the reason for overall toxicity of this approach. In this paper, SWCNT were successfully used to deliver acetylcholine in Alzheimer’s disease brains with high safety range by controlling the doses to ensure lysosomal but not mitochondrial targeting.

Growth of Single-Walled Carbon Nanotubes by Plasma CVD

Recent research in plasma chemical vapor deposition (CVD) for single-walled carbon nanotube (SWNT) growth has achieved low-temperature synthesis, individually freestanding formation, and structure control of diameter, chirality, and length. Detailed growth kinetics of SWNTs are revealed using a combination of techniques for plasma control and nanomaterial analysis. Plasma CVD also allows tube metallicity to be controlled by tuning the mean diameter of SWNTs. This plasma CVD progress contributes to the next stage of nanotube fabrication, which is required for practical use of SWNTs in a variety of applications.

Micro Gas Preconcentrator Made of a Film of Single-Walled Carbon Nanotubes

The development of micro gas preconcentrators is crucial for the realization of miniaturized gas chromatography (micro-GC) systems which are expected to open up new applications such as breath analysis. One of the major problems with the reduction in the preconcentrator size by miniaturization is the availability of a sorbent material having high enough concentration factor. Single-walled carbon nanotubes (SWNTs) are one of the promising materials for high adsorption capacity. In this report, a gas preconcentrator having a depth of 40 μm and a volume of 1 μL was microfabricated. The synthesized SWNT films with a thickness of 30 μm were embedded in the micro gas preconcentrators by using the hot water-assisted detachment method. The small size of the fabricated micro gas preconcentrator and the use of SWNTs as the adsorbent material allow for achieving a concentration factor as high as 16000 for 2 ppm octane. This concentration factor value is the highest reported to date for micro gas preconcentrators and sufficient for micro-GC detectors to concentrate trace analytes of interest for breath analysis. It is concluded that micro gas preconcentrators using SWNTs as the adsorbent material have great potential to concentrate compounds.

Abstract C142: Safety of single-walled carbon nanotubes for delivery of siRNA

Abstract siRNA is a leading potential new cancer therapy but currently lacks an adequate delivery mechanism. Ensysce has been exploring the use of single-walled carbon nanotubes (SWCNT) as delivery vehicles for siRNA delivery and has previously reported on the in vitro and in vivo efficacy of this platform. This study was conducted to determine what if any toxicities result from the use of SWCNT and identify toxicities that may be directly attributed to this delivery vehicle. For this application, it is not only necessary to determine the maximal load of SWCNT that can be tolerated, the dose limiting toxicities and the fate of the material in the body, but also to carefully prepare the SWCNT suspensions to ensure that contaminating metals, nanotube aggregates and other materials are not present when administered systemically. Ensysce Biosciences has been exploring the safe use of this material and here presents its latest findings from a toxicology study where the total dose of 50 and 100 g of fully suspended and individualized SWCNT were administered to groups of 3 mice. Mice were sacrificed at 12, 24, 48 hr and 1 week following i.v. administration. Blood chemistry and hematology were evaluated at each time point. Urine and feces were collected at 12, and 24 hr. Organs, including spleen, liver, kidney, heart, lung and brain were examined macroscopically and by near IR-fluorescence for the presence of SWCNT. The presence and persistence of SWCNT in the tissues was measured. Data to be presented will include details of the analytical characterization of the SWCNT preparations that were delivered, showing that the tubes were well dispersed and individualized. At both the 24 hr and 1 week timepoints, blood chemistry and hematology showed no evidence of toxicity, as values for all were within the normal ranges. Macroscopic examination of organs indicated that SWCNT were present in liver and spleen at 24 hr. Near IR-fluorescence spectroscopy demonstrated that the nanotube accumulation in the spleen decreased over a 1 week period. Data will be presented showing that a 100 g dose (equivalent to 30 mg in humans) was well tolerated and non-toxic. These studies have led to further work examining limits for use of SWCNT for siRNA delivery, including stability of the siRNA complexes in serum, siRNA loading efficiency and systemic efficacy. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C142.

The Chemistry of Single-Walled Nanotubes

AbstractThe unique structural, electronic, and mechanical properties of single-walled carbon nanotubes (SWNTs) have opened the doors to developments that push the limits of science. These advancements not only further scientific discovery, but also result in the development of everyday practical applications. These applications vary from singlemolecule sensors to nano-scaled transistors to multi-modal biosensors. This article focuses on three distinct developments made as a result of recent advances in spectroscopy of SWNTs. The first system examines the use of SWNTs for molecular detection using near-infrared light to produce tunable fluorescent sensors that are highly photostable. The second system examines the use of a 4-hydroxybenzene diazonium reagent to sort SWNTs based on electronic structure to create on-chip modifications of nano-electronic devices. The third system characterizes nanotube networks for such applications as flexible electronics, exploring the irreversible binding of adsorbates onto nanotube networks using electrical transport and Raman spectroscopy.

Transfer Characteristics of Interfacial Stresses Between Carbon Nanotubes and Matrix

This study reports the result of an investigation into the effects of chiral vector of carbon nanotubes (CNTs) and modulus of matrix on the interfacial stresses of CNT-reinforced composites. Based on the molecular structural mechanics approach, the assumption that CNTs and matrix are perfectly bonded to each other, and the equation of multi-node constraints, the molecular structural mechanics model of single/multi-walled CNT-reinforced composites is established. Results show that the use of Armchair CNTs may be more beneficial than the use of Zigzag CNTs in CNT-reinforced composites when the radius of Armchair CNT is equal to that of the Zigzag CNT, and the matrix with higher elastic modulus may be more beneficial in CNT-reinforced composite structures. Besides, it is found that the load transfer efficiency from van der Waals force is only about 30%, so that the use of single-walled CNTs may be more beneficial than the use of multi-walled structures in CNT-reinforced composite structures.

Imaging The Distribution of Individual Platinum-Based Anticancer Drug Molecules Attached to Single-Wall Carbon Nanotubes

To image the distribution of drug molecules attached to single-wall carbon nanotubes (SWNTs). Herein we report the use of scanning transmission electron microscopy (STEM) for atomic scale visualization and quantitation of single platinum-based drug molecules attached to SWNTs designed for targeted drug delivery. Fourier transform infrared spectroscopy and energy-dispersive x-ray spectroscopy were used for characterization of the SWNT drug conjugates. Z-contrast STEM imaging enabled visualization of the first-line anticancer drug cisplatin on the nanotubes at single molecule level. The identity and presence of cisplatin on the nanotubes was confirmed using energy-dispersive x-ray spectroscopy and Fourier transform infrared spectroscopy. STEM tomography was also used to provide additional insights concerning the nanotube conjugates. Finally, our observations provide a rationale for exploring the use of SWNT bioconjugates to selectively target and kill squamous cancer cells. Z-contrast STEM imaging provides a means for direct visualization of heavy metal containing molecules (i.e., cisplatin) attached to surfaces of carbon SWNTs along with distribution and quantitation.

Dielectric oil coated single-walled carbon nanotube electrodes for stable, large-strain actuation with dielectric elastomers

Dielectric elastomers have shown remarkably large actuation strain and energy density. A wide range of novel applications have been conceptualized, but commercial devices have not materialized due to the high rates of failure during high-strain actuation. We report that the use of single-walled carbon nanotube (SWNT) layers with thicknesses in the tens of nanometers as the compliant electrodes in combination with dielectric oil can prolong the actuation durability by at least one order of magnitude. Even though the ultrathin SWNT electrodes can undergo localized self-clearing in the event of electrical breakdown, effectively deactivating the fault and enabling self-healing of the device, extended duration actuation at strains larger than 100% in area cannot be achieved. This is due to corona discharge of the highly porous SWNT electrodes that have sharp tips that amplify the electric field. We show that by applying a dielectric oil coating on the SWNT electrodes, the corona discharging is quenched and continuous actuation at larger than 150% strain for longer than 1500 min can be achieved. The combination of self-clearable SWNT electrodes with dielectric oil coating should improve the manufacturing yield and operational reliability of dielectric elastomer artificial muscles and push them closer to commercialization.

High-Frequency Performance of Submicrometer Transistors That Use Aligned Arrays of Single-Walled Carbon Nanotubes

The unique electronic properties of single-walled carbon nanotubes (SWNTs) make them promising candidates for next generation electronics, particularly in systems that demand high frequency (e.g., radio frequency, RF) operation. Transistors that incorporate perfectly aligned, parallel arrays of SWNTs avoid the practical limitations of devices that use individual tubes, and they also enable comprehensive experimental and theoretical evaluation of the intrinsic properties. Thus, devices consisting of arrays represent a practical route to use of SWNTs for RF devices and circuits. The results presented here reveal many aspects of device operation in such array layouts, including full compatibility with conventional small signal models of RF response. Submicrometer channel length devices show unity current gain (f(t)) and unity power gain frequencies (f(max)) as high as approximately 5 and approximately 9 GHz, respectively, with measured scattering parameters (S-parameters) that agree quantitatively with calculation. The small signal models of the devices provide the essential intrinsic parameters: saturation velocities of 1.2 x 10(7) cm/s and intrinsic values of f(t) of approximately 30 GHz for a gate length of 700 nm, increasing with decreasing length. The results provide clear insights into the challenges and opportunities of SWNT arrays for applications in RF electronics.

Spectroscopic Evidence for Interaction of Poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] Conformers and Single-Walled Carbon Nanotubes in Solvent Dispersions

Organic photovoltaic devices promise low-cost, flexible options for future renewable energy that will reduce reliance on oil. Single-wall carbon nanotubes (SWCNTs) provide possibilities for increasing the efficiency of organic solar cells through increasing conductivity of composites used in such devices or through use as a charge acceptor in a bulk heterojunction device. We present data to indicate the physical interaction of SWCNTs with a conjugated polymer, poly[2'-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), on the basis of the spectroscopic assignments of various conformational species of different optical signature in N,N-dimethylacetamide (DMA) dispersions. We go on to show that energy transfer from nonaggregated MEH-PPV leads to enhanced SWCNT fluorescence in solutions of poorer solvent quality. Energy transfer from polymer chain lengths that are torsionally restricted is not observed. This would suggest that any electron transfer taking place is occurring through a concerted Dexter mechanism and that use of SWCNTs as an electron acceptor will likely have associated drawbacks.

Quantum dynamics of hydrogen interacting with single-walled carbon nanotubes

We perform spin-polarized density functional theory calculations for a hydrogen atom interacting exohedrally with a (5,5) single-walled carbon nanotube (SWNT). We also perform full three-dimensional (3D) quantum dynamics calculations of the H atom bound rovibrational states. We initially focus on the four sites of highest symmetry, along which we compute potential energy surface (PES) values at 33 separate, nonuniformly spaced radial values. These 132 geometries are sufficient to define the primary potential interaction regions. We find a weak physisorptive region between 2.5 and 3.5 A from the SWNT wall, with a maximum well depth of 51 meV, relative to the desorption limit. We also find a chemisorptive region, extending from about 1.0 out to 1.5 A from the SWNT wall. The maximum well depth of 0.755 eV occurs at 1.15 A from the SWNT wall, nearly directly above a carbon atom. A small barrier of 54 meV lies between these two binding regions. There are also two types of transition states that lie between adjacent chemisorption wells. In addition to the high-symmetry sites, a detailed and accurate characterization of the PES requires density functional theory calculations along a large number of interstitial sites-18 in all. Using these 18x33 geometries, and exploiting the full D(10h) symmetry of the system, we fit a global analytical PES, using a Fourier basis in the cylindrical coordinates, with radially dependent expansion coefficients (rms error 3.8 meV). We then perform a mixed spectral basis/phase-space optimized discrete variable representation calculation of all bound rovibrational H atom eigenfunctions and energy levels. We also discuss ramifications for the possible use of SWNTs as hydrogen storage devices.

Direct Growth of Single-Walled Carbon Nanotubes without Metallic Residues by Using Lead as a Catalyst

The IVA group metal Pb was found to be an efficient catalyst for the chemical vapor deposition (CVD) growth of single-walled carbon nanotubes (SWCNTs) under suitable conditions. Especially the volatility of Pb made it feasible to realize the direct growth of SWCNTs with no metallic catalyst residues. Three methods including a low gas flow process, a fast-heating process, and a polymer-assisted process were used to control the volatility of lead at a suitable level. Both random SWCNT networks and horizontally aligned SWCNT arrays were efficiently grown on silicon wafers. The density of the SWCNT arrays can be altered by the CVD conditions. The electrical transport measurements for single tubes show that the produced SWCNTs are of high quality. These directly prepared SWCNTs with no metallic impurities will greatly benefit the study of the intrinsic properties of SWCNTs and are very important for making use of SWCNTs in nanodevices and in biological systems.