Multi-walled Carbon Nanotube Fibers Research Articles

A Novel and Disposable Enzyme-Labeled Amperometric Immunosensor Based on MWCNT Fibers forListeria monocytogenesDetection

A sensitive and specific immunosensor was developed by immobilizing HRP-labeled antibody againstListeria monocytogenesonto the surface of the novel multiwalled carbon nanotube fibers. Firstly, the influence of immunoelectrode modification methods (chemical and physical method) on detection sensitivity and stability was studied. Next, immunosensor was developed, optimized, and applied for the detection ofL. monocytogenes. The morphology was characterized by scanning electron microscopy (SEM), and electrochemical behaviors were by cyclic voltammetry. SEM image, relative response (%), and current data showed chemical modification for immunoelectrode was helpful to capture more target bacteria and obtain more stable current response, resulting in improving the detection sensitivity. The linear relationship betweenL. monocytogenesconcentration andΔIpcwas from 102to 105 cfu/mL (R2=0.993), and LOD was1.07×102 cfu/mL.L. monocytogenesin mixed bacteria (1.51 × 103 cfu/mL) of milk sample (S/N > 14) were detected by developed immunosensor, showing good specificity. Good storage stability and reproducibility (RSD < 6.5%) also showed the potential application of immunosensor for the rapid detection ofL. monocytogenes.

High performance fiber-shaped solar cells

Abstract This short review summarizes our recent progress in fiber-shaped solar cells based on carbon nanomaterials. Highly efficient fiber-shaped solar cells based on graphene/platinum composite fibers were developed with a certified power conversion efficiency of 8.45%. Furthermore, stretchable fiber-shaped solar cells were realized by designing elastic conducting multi-walled carbon nanotube fibers with a novel rotation-translation method. These solar cells were further integrated with fiber-shaped supercapacitors to simultaneously achieve energy conversion and storage. These fiber-shaped energy devices can be woven into textile as next-generation power source for various portable electronic devices.

Mechanism of induction of binucleated cells by multiwalled carbon nanotubes as revealed by live-cell imaging analysis.

IntroductionAsbestos-induced formation of mesothelioma has been attributed to phenotypic and morphological changes in cells caused by polyploidization and aneuploidization, and multiwalled carbon nanotubes (MWCNTs) are suspected to have similar adverse effects due to the similarity in their physical form. MWCNTs and crocidolite, a kind of asbestos, show similar genotoxicity characteristics in vitro, including induction of binucleated cells. We here focused on the mechanisms underlying polyploidization during cell division on exposure to MWCNTs and conducted confocal live-cell imaging analysis using MDA-435 human breast cancer cells in which chromosomes and centromeres were visualized using fluorescent proteins.FindingsDuring anaphase, relatively short MWCNT fibers (approximately 5 μm) migrated rapidly to either of the daughter cells, whereas some long MWCNT fibers (approximately 20 μm) remained inside the contractile ring and induced the formation of binucleated cells through impairment of cytokinesis. This toxicity mechanism has also been observed with crocidolite.ConclusionsOur findings indicate that the mechanism of polyploidization by MWCNTs is very similar to that observed with crocidolite.Electronic supplementary materialThe online version of this article (doi:10.1186/s41021-015-0003-y) contains supplementary material, which is available to authorized users.

Commingled nanocomposites of LDPE/PP/Nylon 6/EPDM reinforced with MWCNT and Kenaf Fiber with enhanced mechanical, thermal and flammability characteristics

Abstract Multicomponent commingled composites comprised of LDPE, PP, Nylon 6 and EPDM have been prepared using a mixture of two epoxy functionalized polyolefins as compatibilizers to enhance interfacial interactions. Kenaf fiber has also been added for reinforcement along with Multiwalled carbon nanotube (MWCNT). The mechanical and thermal properties for the nancomposites have been determined and assessed using predictive theories. The flammability characteristics for the nanocomposites were also assessed. The presence of MWCNT enhanced mechanical properties and also promoted char formation along with improved fire retardancy of the nanocomposites. These composites have potential for application as high performance fire retardant materials by recycling mixed plastic waste.

Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement

The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite.Nylon-6 was dissolved in hexafluoropropanol (10wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120rpm) or high-speed (6000rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20×2×2mm3) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey׳s test (α=5%).Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes׳ presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5wt%.

Design, Manufacture and Analysis of Composite Epoxy Material with Embedded MWCNT Fibers

Abstract The weight and fuel savings offered by composite materials make them attractive not only to the military, but also to the civilian aircraft, space, and automobile industries. In these industries, bolted and riveted joints are extensively used as a primary method for structural joining. Bolted joints in composite materials have complex failure modes, and hence the demand for improving their performance exists. The main objective of this work is to improve the performance of bolted joints in composite structures by introducing nanoparticles/fibers around the expected failure zone. The literature on this issue showed shortcomings in the investigations of such materials. Most of the investigations in this field aimed to enhance the mechanical properties of epoxy materials, which cannot be used alone for high performance structural applications due to their low mechanical properties. In the present work, epoxy resin was modified with different types of nanofillers including multi walled carbon nanotubes (MWCNT). Nano-phased epoxy was used to fabricate different types of nanocomposites as well as nano-hybridized glass fiber reinforced composite laminates. Therefore, six different advanced materials were fabricated including a nanocomposite material (MWCNT/E), a quasi-isotropic nano-hybridized composite laminate (QI-GFR/MWCNT/E), a unidirectional nano-hybridized composite laminate (UD-GFR/MWCNT/E) and a control panel manufactured without nano-fillers (neat epoxy, QI-GFR/E, UD-GFR/E). The materials were characterized by tension and compression tests. The obtained properties are essential for the validation of respective finite element analysis. The results showed improvements in the tensile and compressive properties (strength and modulus) of the fabricated nanocomposites (MWCNT/E) compared with neat epoxy. The hybridized composite laminate with MWCNT showed high improvements in their mechanical properties compared to the composite laminates without nanofillers.

Effects of MWCNT and nickel-coated carbon fiber on the electrical and morphological properties of polypropylene and polyamide 6 blends

In this study, the effects of hybrid fillers such as multi-walled carbon nanotube (MWCNT) and nickelcoated carbon fiber (NCCF) on the electrical conductivity of polypropylene (PP) and polyamide 6 (PA6) blends were investigated. Polypropylene-g-maleic anhydride (PP-g-MAH) was used as a compatibilizer of the PP/PA6 blends. From the results of the transmission electron micrographs of the PP/PA6 (70/30)/MWCNT composites, the MWCNT preferred to locate more in the PA6 phase than in the PP phase. This was possibly due to the lower interfacial tension of the PA6/MWCNT composite compared to that of the PP/MWCNT composite. For the PP/PA6 (70/30)/NCCF/MWCNT (3 phr) hybrid filler composites, values of the electrical conductivities were increased with the increase of the NCCF content. The increase in electrical conductivity was possibly due to the increased electrical pathway with the addition of NCCF content. From the results of the electrical conductivity and morphology of the PP/PA6/NCCF/MWCNT composites, it is suggested that selective localization of the MWCNT in the PA6 phase affected the increased electrical conductivity of the PP/PA6/NCCF/MWCNT composites. The hybrid fillers NCCF and MWCNT could produce a synergistic effect on the electrical conductivity, and the electromagnetic interference shielding efficiency (EMI SE) of the PP/PA6 (70/30)/NCCF/MWCNT composites.

Preparation of Weavable, All‐Carbon Fibers for Non‐Volatile Memory Devices

Woven into your memories: Aligned multi-walled carbon nanotube (MWCNT) fibers are coated by a thin layer of graphene oxide (GO). The MWCNT fibers work as the top and bottom electrodes while the GO acts as the active layer. By simply cross-stacking two MWCNT@GO fibers, the memory cell obtained shows a write-once-read-many-times effect (see picture).

Distribution and fibrotic response following inhalation exposure to multi-walled carbon nanotubes.

BackgroundPrior studies have demonstrated a rapid and progressive acute phase response to bolus aspiration of multi-walled carbon nanotubes (MWCNTs). In this study we sought to test the hypothesis that inhalation exposure to MWCNT produces a fibrotic response and that the response is chronically persistent. To address the hypothesis that inhaled MWCNTs cause persistent morphologic changes, male C57BL/6 J mice were exposed in a whole-body inhalation system to a MWCNT aerosol and the fibrotic response in the alveolar region examined at up to 336 days after termination of exposure.MethodsInhalation exposure was to a 5 mg/m3 MWCNT aerosol for 5 hours/day for 12 days (4 times/week for 3 weeks). At the end of inhalation exposures, lungs were either lavaged for analysis of bronchoalveolar lavage (BAL) or preserved by vascular perfusion of fixative while inflated with air at 1, 14, 84, 168 and 336 days post inhalation exposure. Separate, clean-air control groups were also studied. Light microscopy, enhanced darkfield microscopy and field emission electron microscopy (FESEM) of tissue sections were used to analyze the distribution of lung burden following inhalation exposure. Morphometric measurements of Sirius Red staining for fibrillar collagen were used to assess the connective tissue response. Serial section analysis of enhanced darkfield microscope images was used to examine the redistribution of MWCNT fibers within the lungs during the post-exposure period.ResultsAt day 1 post-exposure 84 ± 3 and 16 ± 2 percent of the lung burden (Mean ± S.E., N = 5) were in the alveolar and airway regions, respectively. Initial distribution within the alveolar region was 56 ± 5, 7 ± 4 and 20 ± 3 percent of lung burden in alveolar macrophages, alveolar airspaces and alveolar tissue, respectively. Clearance reduced the alveolar macrophage burden of MWCNTs by 35 percent between 1 and 168 days post-exposure, while the content of MWCNTs in the alveolar tissue increased by 63 percent. Large MWCNT structures containing greater than 4 fibers were 53.6 percent of the initial lung burden and accounted for the majority of the decline with clearance, while lung burden of singlet MWCNT was essentially unchanged. The mean linear intercept of alveolar airspace, a measure of the expansion of the lungs, was not significantly different between groups. Pulmonary inflammation and damage, measured as the number of polymorphnuclear leukocytes (PMNs) or lactate dehydrogenase activity (LDH) and albumin in BAL, increased rapidly (1 day post) after inhalation of MWCNTs and declined slowly with time post-exposure. The fibrillar collagen in the alveolar region of MWCNT-exposed mice demonstrated a progressive increase in thickness over time (0.17 ± 0.02, 0.22 ± 0.02, 0.26 ± 0.03, 0.25 ± 0.02 and 0.29 ± 0.01 microns for 1, 14, 84, 168 and 336 days post-exposure) and was significantly different from clean-air controls (0.16 ± 0.02) at 84 and (0.15 ± 0.02) at 336 days post-exposure.ConclusionsDespite the relatively low fraction of the lung burden being delivered to the alveolar tissue, the average thickness of connective tissue in the alveolar region increased by 70% in the 336 days after inhalation exposure. These results demonstrate that inhaled MWCNTs deposit and are retained within the alveolar tissue where they produce a progressive and persistent fibrotic response up to 336 days post-exposure.

Multi-walled carbon nanotubes induce visceral mesothelial proliferation in rats. An enlarged picture around the ligand is shown. Scanning electron microscope observation demonstrates the existence of the multi-walled carbon nanotube fibers in the cell pel

Multi-walled carbon nanotubes induce visceral mesothelial proliferation in rats. An enlarged picture around the ligand is shown. Scanning electron microscope observation demonstrates the existence of the multi-walled carbon nanotube fibers in the cell pel

The Alignment of Carbon Nanotubes: An Effective Route To Extend Their Excellent Properties to Macroscopic Scale

To improve the practical application of carbon nanotubes, it is critically important to extend their physical properties from the nanoscale to the macroscopic scale. Recently, chemists aligned continuous multiwalled carbon nanotube (MWCNT) sheets and fibers to produce materials with high mechanical strength and electrical conductivity. This provided an important clue to the use of MWCNTs at macroscopic scale. Researchers have made multiple efforts to optimize this aligned structure and improve the properties of MWCNT sheets and fibers. In this Account, we briefly highlight the new synthetic methods and promising applications of aligned MWCNTs for organic optoelectronic materials and devices. We describe several general methods to prepare both horizontally and perpendicularly aligned MWCNT/polymer composite films, through an easy solution or melting process. The composite films exhibit the combined properties of being flexible, transparent, and electrically conductive. These advances may pave the way to new flexible substrates for organic solar cells, sensing devices, and other related applications. Similarly, we discuss the synthesis of aligned MWCNT/polymer composite fibers with interesting mechanical and electrical properties. Through these methods, we can incorporate a wide variety of soluble or fusible polymers for such composite films and fibers. In addition, we can later introduce functional polymers with conjugated backbones or side chains to improve the properties of these composite materials. In particular, cooperative interactions between aligned MWCNTs and polymers can produce novel properties that do not occur individually. Common examples of this are two types of responsive polymers, photodeformable azobenzene-containing liquid crystalline polymer and chromatic polydiacetylene. Aligning the structure of MWCNTs induces the orientation of azobenzene-containing mesogens, and produces photodeformable polymer elastomers. This strategy also solves the long-standing problems from the traditional mechanical rubbing method, which include production of broken debris and structure damage during fabrication and building up electrostatic charge during use. Aligning MWCNTs induces a conformational change in polydiacetylene, which causes the composite fibers to be electrochromatic, a previously unknown reaction in chromatic polymers. Due to their large surface area, flexibility, electrical conductivity, and remarkable electrocatalytic activity, aligned MWCNT films can be used as counter electrodes to produce highly efficient dye-sensitized solar cells. In addition, chemists have developed new electrodes from the aligned MWCNT fibers to make a family of high-performing, wire-shaped dye-sensitized solar cells.

Headspace solid-phase microextraction using poly(ethylene glycol) grafted multi-walled carbon nanotube fibers for the determination of methyl tert-butyl ether in water samples

A simple, sensitive, and accurate method for the determination of methyl tert-butyl ether (MTBE) in water samples has been developed based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-flame ionization detection (GC-FID). A sol–gel based coating fiber using poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) as the extraction phase was prepared and used for the extraction of MTBE. The relative standard deviations (RSDs) for one fiber (repeatability) (n = 6) and between fibers or batch to batch (reproducibility) (n = 3) were obtained. The repeatability was assessed at low (0.1 ng mL−1) and high (100 ng mL−1) concentrations and the RSDs obtained were 5.3 and 4.1%, respectively. The reproducibility obtained for a concentration of 0.1 ng mL−1 was 6.5%. The calibration curve of MTBE was linear in the range from 0.07 to 500 ng mL−1. The limits of detection (S/N = 3) of 0.01 ng mL−1 and the limits of quantification (S/N = 10) of 0.07 ng mL−1 were obtained. The developed method was applied successfully to determine trace level of MTBE in real water samples. The relative recoveries for the spiked samples with 5 ng mL−1 of MTBE were ranged from 91 to 112% and the relative standard deviations were less than 7.8%.

Aerosol generation and measurement of multi-wall carbon nanotubes

Mass production of some kinds of carbon nanotubes (CNT) is now imminent, but little is known about the risk associated with their exposure. It is important to assess the propensity of the CNT to release particles into air for its risk assessment. In this study, we conducted aerosolization of a multi-walled CNT (MWCNT) to assess several aerosol measuring instruments. A Palas RBG-1000 aerosol generator applied mechanical stress to the MWCNT by a rotating brush at feed rates ranging from 2 to 20 mm/h, which the MWCNT was fed to a two-component fluidized bed. The fluidized bed aerosol generator was used to disperse the MWCNT aerosol once more. We monitored the generated MWCNT aerosol concentrations based on number, area, and mass using a condensation particle counter and nanoparticle surface area monitor. Also we quantified carbon mass in MWCNT aerosol samples by a carbon monitor. The shape of aerosolized MWCNT fibers was observed by a scanning electron microscope (SEM). The MWCNT was well dispersed by our system. We found isolated MWCNT fibers in the aerosols by SEM and the count median lengths of MWCNT fibers were 4–6 μm. The MWCNT was quantified by the carbon monitor with a modified condition based on the NIOSH analytical manual. The MWCNT aerosol concentration (EC mass base) was 4 mg/m3 at 2 mm/h in this study.