Potential Of Multi-walled Carbon Nanotubes Research Articles

Modified toxic potential of multi-walled carbon nanotubes to zebrafish (Danio rerio) following a two-year incubation in water

Multi-walled carbon nanotubes (MWCNTs), widely used in several industrial fields, are not readily degradable thus, persist in environmental matrices, serving as a source of environmental toxicity to organisms. However, the effects of environmental weathering on nanomaterial toxicity remain unclear. Herein, we prepared aged-MWCNTs (a-CNTs) by incubating commercial pristine-MWCNTs (p-CNTs) for two years and compared their changes in physicochemical properties and toxic effects on zebrafish. The characterization of a-CNTs by transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and Fourier-transform infrared spectroscopy showed an increased surface area, pore size, structural defects, and surface oxidation than those of p-CNTs. Zebrafish were exposed to 100 mg/L p-CNT and a-CNT for four days. Subsequently, the mRNA expression of antioxidant enzymes, including cat, gst, and sod, in a-CNT group increased by 1.5- to 1.7-fold, consistent with increased expression of genes associated with inflammation (interleukin-8) and apoptosis (p53) compared to control. The higher toxicity of a-CNTs to zebrafish than p-CNT might be due to the increased oxidative potential by altered physicochemical properties. These findings provide new insights into the risk assessment and environmental management of MWCNTs in the aquatic environment. However, further testing at environmentally relevant doses, different exposure durations, and diverse weathering parameters is warranted.

Exploring potential of multi-walled carbon nanotubes to establish efficient callogenesis, elicitation of phenolic compounds and antioxidative activities in thyme plants (Thymus daenensis): An in vitro assay

Exploring potential of multi-walled carbon nanotubes to establish efficient callogenesis, elicitation of phenolic compounds and antioxidative activities in thyme plants (Thymus daenensis): An in vitro assay

Oxidative Stress in Long-Term Exposure to Multi-Walled Carbon Nanotubes in Male Rats

Multi-walled carbon nanotubes (MWCNTs) serve as nanoparticles due to their size, and for that reason, when in contact with the biological system, they can have toxic effects. One of the main mechanisms responsible for nanotoxicity is oxidative stress resulting from the production of intracellular reactive oxygen species (ROS). Therefore, oxidative stress biomarkers are important tools for assessing MWCNTs toxicity. The aim of this study was to evaluate the oxidative stress of multi-walled carbon nanotubes in male rats. Our animal model studies of MWCNTs (diameter ~15-30 nm, length ~15-20 μm) include measurement of oxidative stress parameters in the body fluid and tissues of animals after long-term exposure. Rattus Norvegicus/Wistar male rats were administrated a single injection to the knee joint at three concentrations: 0.03 mg/mL, 0.25 mg/mL, and 0.5 mg/mL. The rats were euthanized 12 and 18 months post-exposure by drawing blood from the heart, and their liver and kidney tissues were removed. To evaluate toxicity, the enzymatic activity of total protein (TP), reduced glutathione (GSH), glutathione S-transferase (GST), thiobarbituric acid reactive substances (TBARS), Trolox equivalent antioxidant capacity (TEAC), nitric oxide (NO), and catalase (CAT) was measured and histopathological examination was conducted. Results in rat livers showed that TEAC level was decreased in rats receiving nanotubes at higher concentrations. Results in kidneys report that the level of NO showed higher concentration after long exposure, and results in animal serums showed lower levels of GSH in rats exposed to nanotubes at higher concentrations. The 18-month exposure also resulted in a statistically significant increase in GST activity in the group of rats exposed to nanotubes at higher concentrations compared to animals receiving MWCNTs at lower concentrations and compared to the control group. Therefore, an analysis of oxidative stress parameters can be a key indicator of the toxic potential of multi-walled carbon nanotubes.

Effect of surfactant on functionalized multi-walled carbon nano tubes enhanced salt hydrate phase change material

Phase change materials (PCMs) are effective thermal energy storage materials; however, their low thermal conductivity nature tends to affect heat storage performance. Salt hydrate being inexpensive, incombustible and ensuring high phase change enthalpy, are highly attractive for energy storage. The potential of multi-walled carbon nanotubes (MWCNTs) in improving the thermophysical properties of salt hydrate PCMs makes it a hotspot of current research. Therefore, in this research article, MWCNTs and functionalized multi-walled carbon nanotubes (FMWCNTs) nanoparticles were dispersed with inorganic salt hydrate at different concentrations (0.3, 0.5, and 1.0 wt%), in the presence and absence of surfactant. The role of surfactant with salt hydrate PCM has been discussed extensively. The results obtained have ensured an enhancement in melting enthalpy of prepared composites by 4.92 %, and 28.5 % for 0.5 wt% MWCNT dispersed PCM (SHM0.5), and 0.5 wt% FMWCNT dispersed PCM (SHF0.5), respectively. Furthermore, the maximum thermal conductivity was enhanced by 50.0 % and 84.78 % for 0.5 wt% MWCNT dispersed PCM with surfactant (SHMS0.5), and SHF0.5 respectively, compared to salt hydrate PCM. From the improvement in thermal conductivity, light absorptance, thermal stability, latent heat, and chemical stability, it is evident that the prepared nanocomposite is a potential candidate for solar thermal energy storage applications.

Two-year intermittent exposure of a multiwalled carbon nanotube by intratracheal instillation induces lung tumors and pleural mesotheliomas in F344 rats

BackgroundA mounting number of studies have been documenting the carcinogenic potential of multiwalled carbon nanotubes (MWCNTs); however, only a few studies have evaluated the pulmonary carcinogenicity of MWCNTs in vivo. A 2-year inhalation study demonstrated that MWNT-7, a widely used MWCNT, was a pulmonary carcinogen in rats. In another 2-year study, rats administered MWNT-7 by intratracheal instillation at the beginning of the experimental period developed pleural mesotheliomas but not lung tumors. To obtain data more comparable with rats exposed to MWNT-7 by inhalation, we administered MWNT-7 to F344 rats by intratracheal instillation once every 4-weeks over the course of 2 years at 0, 0.125, and 0.5 mg/kg body weight, allowing lung burdens of MWNT-7 to increase over the entire experimental period, similar to the inhalation study.ResultsAbsolute and relative lung weights were significantly elevated in both MWNT-7-treated groups. Dose- and time-dependent toxic effects in the lung and pleura, such as inflammatory, fibrotic, and hyperplastic lesions, were found in both treated groups. The incidences of lung carcinomas, lung adenomas, and pleural mesotheliomas were significantly increased in the high-dose group compared with the control group. The pleural mesotheliomas developed mainly at the mediastinum. No MWNT-7-related neoplastic lesions were noted in the other organs. Cytological and biochemical parameters of the bronchoalveolar lavage fluid (BALF) were elevated in both treated groups. The lung burden of MWNT-7 was dose- and time-dependent, and at the terminal necropsy, the average value was 0.9 and 3.6 mg/lung in the low-dose and high-dose groups, respectively. The number of fibers in the pleural cavity was also dose- and time-dependent.ConclusionsRepeated administration of MWNT-7 by intratracheal instillation over the 2 years indicates that MWNT-7 is carcinogenic to both the lung and pleura of rats, which differs from the results of the 2 carcinogenicity tests by inhalation or intratracheal instillation.

Assessing the electrical property of carbon nanotube reinforced oxide ceramic matrix composites produced by ceramic injection moulding

Owing to its remarkable properties, multiwalled carbon nanotubes (MWCNTs) are attracting the interest for realization of sensors. The potential of MWCNTs for high temperature sensing applications was investigated by integration within reinforced aluminium oxide ceramic composite. MWCNTs up to 2 wt% were mixed with reinforced aluminum oxide ceramic composite using solution mixing method to ensure good homogeneilty of the oxide ceramic composite powders. Specimens were realized using ceramic injection moulding process (CIM) followed by debinding and sintering procedures. The topography of specimens were examined using atomic force microscopy (AFM). Electrical measurements were also carried out. The results show good demouldability at high MWCNTs concentration and homogenous distribution of the MWCNTs within the oxide ceramic matrix. AFM images illustrate the reduction of surface roughness by increasing the MWCNTs content which demonstrates the role of MWCNTs to improve the fracture resistance of the oxide ceramic matrix composite. As well, the electrical resistance of the feedstocks were reduced sharply. After sintering process, the resistance range drops enormously from M Ω to reach 12.1 Ω at low MWCNTs content; which make them suitable to be as electrode with high temperature capability. The electrical resistance temperature dependency shows a negative temperature coefficient behaviour with negligible resistance change.

Synergistic effect of ultrasonically assisted exfoliated MWCNTs by ZrO2 nanoparticles on thermo-mechanical and anti-corrosive properties of epoxy nanocomposites

Exploiting the boundless potential of multi-walled carbon nanotubes (MWCNTs) is the critical issue in developing multifunctional nanocomposites. In this study, the MWCNTs are exfoliated by ZrO2 nanoparticles using the ultrasonication technique. The obtained MWCNT/ZrO2 hybrid nanofiller is infused in the epoxy matrix to produce multifunctional nanocomposites with superior thermo-mechanical and anti-corrosive properties. The physical, morphological, and structural properties of MWCNT/ZrO2 hybrid nanofiller are successfully studied by using XRD crystallography, Raman spectroscopy, and transmission electron microscopy analysis. The chemical interaction between the MWCNT/ZrO2 hybrid nanofiller with the epoxy (EP) matrix is evaluated using FTIR spectroscopy. Results indicated that the corrosion protection performance of mild steel coated with MWCNT/ZrO2 hybrid epoxy nanocomposite (MNC) is considerably increased at 1.0 wt.% of MWCNT/ZrO2 hybrid nanofiller by reducing the corrosion rate from 8.82 MPY to 56 × 10−3 MPY. Furthermore, the tensile strength and lap shear strength of MNC with the same loading content is improved by 67.8% and 58.04%, respectively, compared to neat EP. The field emission scanning electron microscopy images of tensile fracture surfaces of MNC (1.0 wt.%) confirm the cluster-free uniform dispersion of MWCNTs in the EP matrix.

Effect of Multi-Walled Carbon Nanotubes on Infill Material for Pipeline Composite Repair

The properties of the infill material are an important parameter in predicting the performance and behaviour of Fibre Reinforced Polymer (FRP) composite for effective design. This paper identifies the potential of Multi-walled Carbon Nanotubes (MWCNTs) as nanofiller in enhancing the performance of infill material. Two compositions of MWNTs at 0.1% and 0.5% of weight fractional were evaluated toward neat epoxy on tensile and lap shear test. By comparing MWCNTs-based modified epoxy grouts and neat epoxy grout, a significant increase in tensile strength was observed, especially with 0.5% of MWCNTs by almost 53.3%. While the inclusion of MWCNTs showed a comparable increment in shear strength in both 0.1% and 0.5% weight fractional by 13%. The image of morphologies showed that MWCNTs were well incorporated into the matrix, making the cross-section of the fracture rougher by sharing stress. This shows the potential of the MWCNTs in changing the properties of the modified epoxy grout, provided that the MWCNTs are appropriately dispersed throughout the resin matrix.

Multi-walled carbon nanotubes induce airway hyperresponsiveness in human bronchi by stimulating sensory C-fibers and increasing the release of neuronal acetylcholine

ABSTRACT Objectives The potential of multi-walled carbon nanotubes (MWCNTs) in inducing airway hyperresponsiveness (AHR) was investigated in human airways. Methods Human isolated bronchi were exposed to MWCNTs and the contractility to electrical field stimulation (EFS) was measured. Neuronal acetylcholine (ACh) and cyclic adenosine monophosphate (cAMP) were quantified. Some tissues were desensitized by consecutive administrations of capsaicin. Results MWCNTs (100 ng/ml – 100 µg/ml) induced AHR (overall contractile tone vs. negative control: +83.43 ± 11.13%, P < 0.01). The potency was significantly (P < 0.05) greater when airways were stimulated at low frequency (EFS3Hz) then at medium-to-high frequencies (EFS10Hz and EFS25Hz) (delta potency: +2.13 ± 0.74 and +2.40 ± 0.65 logarithms, respectively). In capsaicin-desensitized airways, the AHR to MWCNTs 100 ng/ml was abolished. MWCNTs increased the release of ACh, an effect prevented by capsaicin-desensitization (−90.17 ± 18.59%, P < 0.05). MWCNTs did not alter the level of cAMP. Conclusion MWCNTs administered at low concentrations elicit AHR in human airways by activating sensory C-fibers and, in turn, increasing the release of neuronal ACh. Our results suggest that work is required to understand the impact of MWCNTs in patients at risk of AHR, such as those suffering from chronic obstructive respiratory disorders.

Removing of Anionic Dye from Aqueous Solutions by Adsorption Using of Multiwalled Carbon Nanotubes and Poly (Acrylonitrile-styrene) Impregnated with Activated Carbon

This paper presents an estimation of the adsorptive potential of multiwalled carbon nanotubes (MWCNTs) and modified poly (acrylonitrile-co-styrene) with activated carbon for the uptake of reactive red 35 (RR35) dye from aqueous solution by a batch system. MWCNT adsorbent was synthesized by encapsulation via in situ polymerization. The copolymer material of poly (acrylonitrile-styrene) P (AN-co-ST) was prepared in a ratio of 2:1 V/V by the precipitation polymerization process. The prepared composites’ properties were characterized by FTIR, SEM, Raman, mean particle size (PSA), and XRD analysis. The PSA of the copolymeric material was determined to be 450.5 and 994 nm for MWCNTs and P(AN-co-St)/AC, respectively. Moreover, the influences of different factors, for example pH (2–10), adsorbents dosage (0.005–0.04 g), contact time (5–120 min), initial dye concentration (10–50 mg L−1), and temperature (25–55 °C). The optimum values were determined to be 2 and 4 pH, 10 mg L−1 of RR35 dye, and 0.04 g of adsorbents at early contact time. Furthermore, the adsorption isotherm was studied using Langmuir, Freundlich, Tempkin, and Halsey models. Maximum capacity qmax for MWCNTS and P (AN-co-St)/AC was 256.41 and 30.30 mg g−1, respectively. The investigational kinetic study was appropriated well via a pseudo second-order model with a correlation coefficient around 0.99. Thermodynamic study displayed that the removal of RR35 is exothermic, a spontaneous and physisorption system. The adsorption efficiency reduced to around 54–55% of the RR35 after four cycles of reuse of the adsorbents at 120 min.

An In Vitro Lung System to Assess the Proinflammatory Hazard of Carbon Nanotube Aerosols.

In vitro three-dimensional (3D) lung cell models have been thoroughly investigated in recent years and provide a reliable tool to assess the hazard associated with nanomaterials (NMs) released into the air. In this study, a 3D lung co-culture model was optimized to assess the hazard potential of multiwalled carbon nanotubes (MWCNTs), which is known to provoke inflammation and fibrosis, critical adverse outcomes linked to acute and prolonged NM exposure. The lung co-cultures were exposed to MWCNTs at the air-liquid interface (ALI) using the VITROCELL® Cloud system while considering realistic occupational exposure doses. The co-culture model was composed of three human cell lines: alveolar epithelial cells (A549), fibroblasts (MRC-5), and macrophages (differentiated THP-1). The model was exposed to two types of MWCNTs (Mitsui-7 and Nanocyl) at different concentrations (2–10 μg/cm2) to assess the proinflammatory as well as the profibrotic responses after acute (24 h, one exposure) and prolonged (96 h, repeated exposures) exposure cycles. The results showed that acute or prolonged exposure to different concentrations of the tested MWCNTs did not induce cytotoxicity or apparent profibrotic response; however, suggested the onset of proinflammatory response.

Structural and magnetic properties of rare-earth-free MnAl(MCNT)/Fe nanocomposite magnets processed by resin-bonding technique

In this study, the potential of multi-walled carbon nanotubes (MCNT) in processing rare-earth-free MnAl(MCNT)/Fe nanocomposite magnets was exploited through adopting a combination of surfactant-assisted milling and resin-bonding techniques. The required hard and soft magnetic phases such as MnAl(MCNT) and α-Fe, respectively, were individually subjected to surfactant-assisted high-energy ball milling. The surfactant-coated MnAl(MCNT) and Fe nanopowders, thus, obtained were characterized with respect to their structural and magnetic properties. Relatively, a very high coercivity, Hc (4.48 kOe), was obtained for the surfactant-coated MnAl(MCNT) powders after 6 h of milling, while in the case of Fe powders with high saturation magnetization, Ms (218.6 emu/g) was achieved at 3 h of surfactant-assisted milling. The MnAl(MCNT) powders with high Hc were mixed with the Fe powders of high Ms with different weight percentages: 0, 5 and 10. The nanocomposite powder mixtures were further milled for 1 h and then processed in the form of resin bonded magnets under aligning magnetic field of 20 kOe. The obtained bonded nanocomposite magnet, i.e. MnAl(MCNT) with 5 wt% of Fe addition demonstrated a good combination of high Ms (63.7 emu/g) and high Hc (4.46 kOe).

Multi-walled carbon nanotubes upregulate mitochondrial gene expression and trigger mitochondrial dysfunction in primary human bronchial epithelial cells

Nanomaterials are a relatively new class of materials that acquire novel properties based on their reduced size. While these materials have widespread use in consumer products and industrial applications, the potential health risks associated with exposure to them remain to be fully characterized. Carbon nanotubes are among the most widely used nanomaterials and have high potential for human exposure by inhalation. These nanomaterials are known to penetrate the cell membrane and interact with intracellular molecules, resulting in a multitude of documented effects, including oxidative stress, genotoxicity, impaired metabolism, and apoptosis. While the capacity for carbon nanotubes to damage nuclear DNA has been established, the effect of exposure on mitochondrial DNA (mtDNA) is relatively unexplored. In this study, we investigated the potential of multi-walled carbon nanotubes (MWCNTs) to impair mitochondrial gene expression and function in human bronchial epithelial cells (BECs). Primary BECs were exposed to sub-cytotoxic doses (up to 3 μg/ml) of MWCNTs for 5 d and assessed for changes in expression of all mitochondrial protein-coding genes, heteroplasmies, and insertion/deletion mutations (indels). Exposed cells were also measured for cytotoxicity, metabolic function, mitochondrial abundance, and mitophagy. We found that MWCNTs upregulated mitochondrial gene expression, while significantly decreasing oxygen consumption rate and mitochondrial abundance. Confocal microscopy revealed induction of mitophagy by 2 hours of exposure. Mitochondrial DNA heteroplasmy and insertion/deletion mutations were not significantly affected by any treatment. We conclude that carbon nanotubes cause mitochondrial dysfunction that leads to mitophagy in exposed BECs via a mechanism unrelated to its reported genotoxicity.

Impact of different isothermal aging conditions on the IMC layer growth and shear strength of MWCNT-reinforced Sn–5Sb solder composites on Cu substrate

In this study, the effect of multi-walled carbon nanotubes (MWCNTs) reinforcement on the intermetallic compound (IMC) layer growth and shear strength of Sn–5Sb-xCNT/Cu composite solder joints subjected to different isothermal aging conditions has been investigated. A series of plain and composite lead-free solder systems (Sn–5Sb-xCNT; x = 0, 0.01, 0.05 and 0.1 wt%) was successfully developed through the powder metallurgy method. Isothermal aging process was performed on the solder/Cu joints at 120 °C, 150 °C and 170 °C temperatures in order to investigate the evolution of the interfacial IMC layers and the shear strength property. Experimental results showed that the thickness of the total IMC layer increased with rising aging temperature. While the Cu3Sn IMC maintained a layer-type morphology for all aging conditions, morphology of the Cu6Sn5 IMC transformed from a scallop-type to a layer-type after aging at intermediate (150 °C) and high (170 °C) temperatures. Given the potential of MWCNTs as a reinforcement material, significant suppression in IMC layer growth was demonstrated by the composite solder joints relative to the plain counterpart. Comprehensive investigation on the growth kinetics showed that the presence of MWCNTs in the composite solder joints was effective in slowing down the diffusion mechanism responsible for IMC growth. Overall, the Sn–5Sb-0.05CNT composite solder joint exhibited the lowest diffusion coefficient within the range of 0.09 × 10−14- 1.03 × 10−14 cm2/s and 0.95 × 10−14- 9.8 × 10−14 cm2/s for Cu6Sn5 and Cu3Sn IMC layers respectively. Moreover, the strengthening effect of the MWCNTs reinforcement was well marked in the composite solder joints as the maximum shear strength within a range of 24.2–15.2 MPa was exhibited by the Sn-0.01CNT/Cu composite solder joint subjected to reflow soldering and isothermal aging conditions.

Fabrication of epoxy functionalized MWCNTs reinforced PVDF nanocomposites with high dielectric permittivity, low dielectric loss and high electrical conductivity

Nanocomposites of Polyvinylidene Flouride (PVDF) with Multi-walled Carbon Nanotubes (MWCNTs) possess excellent thermal, piezoelectric and conductive behaviors. However, the potential of MWCNTs as filler in polymer composites is hampered by their poor dispersion into the matrix, corresponding to the strong inter-tubular and weak inter tubular-polymer chain interactions. This issue is successfully overcome by utilizing di-glycidyl ether of bisphenol-A (DGEBA) grafted MWCNTs (DG-MWCNTs) as reinforcement in PVDF matrix. To synthesize the desired nanocomposites, the easier to manipulate, solution casting technique was employed. The resulting PVDF/DG-MWCNTs nanocomposites have different loadings of filler ranging from 1.0 wt% to 10 wt%, and have shown variation in the phase transformation from α-phase to β-phase along with improvements in thermal and dielectrical behaviors. It was revealed by the impedance spectroscopy (IS) that the reinforcement of PVDF with DG-MWCNTs leads to an increase in the dielectric permittivity. This increase was found higher enough to reach up to ∼5288 (at ∼100 Hz) and 214 (at ∼102 Hz) for filler loading of 10 wt %. The increase is several hundreds of magnitude i.e., ∼204 at ∼102 Hz higher than the PVDF matrix, while retaining a low level conductivity (4.18 × 10−6 S/cm). This enhancement in the dielectric permittivity is attributed to the strong interfacial interaction between PVDF and DG-MWCNTs, and was explained by the Maxwell-Wagner-Sillar (MWS) effect.

Multi-Walled Carbon Nanotubes as Efficient Sorbent for the Solid Bar Microextraction of non-Steroidal Anti-Inflammatory Drugs from Human Urine Samples

Background: The determination of NSAIDs (ketoprofen, diclofenac, and ibuprofen) in urine samples provides useful information for assessing their safety, therapeutic effect, and their mechanism of action. Urine samples are characterized by their complexity and low concentration of the target analytes, which make their direct analysis difficult. In this work, the potential of multi-walled carbon nanotubes (MWCNTs) as Solid Bar Microextraction (SBME) adsorbents for extraction and preconcentration of selected drugs from urine samples have been investigated. Methods: Five SBME devices (contains 10 mg of MWCNTs) were placed in 30 mL of adjusted pH 2 water samples and stirred for 40 minutes. After finishing the extraction, the devices were ultrasonicated in 250 µL of methanol for 5 min to desorb the selected drugs and analyzed using HPLC-DAD. Results: The analytical performance of the whole method was evaluated in water samples. Limits of detection and quantitation were in the ranges of (0.36- 0.52) and (1.2- 1.7) µg L-1, respectively, and the Relative Standard Deviation (RSD) < 5.7% over a concentration range of 5-100 µg L-1. Application: The proposed method was successfully applied to the analysis of selected drugs in spiked human urine samples. The absolute recovery obtained by spiking the urine samples at three concentration levels: 5, 50 and 100 µg L-1 of selected NSAIDs were from 48.8% to 53.5%. Conclusion: The proposed SBME using MWCNT as a sorbent material can be a useful alternative sample preparation technique for the routine determination of NSAIDs in urine samples at therapeutic levels with very simple sample pretreatment. Furthermore, the application of the developed SBME method might be extended to study the determination of selected non-steroidal anti-inflammatory drugs in veterinary urine samples. Keywords: Multi-walled carbon nanotubes, solid bar microextraction, non-steroidal anti-inflammatory drugs, urine, liquid chromatography, ketoprofen.

Investigating the potential of multiwalled carbon nanotubes based zinc nanocomposite as a recognition interface towards plant pathogen detection

The emergence of nanotechnology has opened new horizons for constructing efficient recognition interfaces. This is the first report where the potential of a multiwalled carbon nanotube based zinc nanocomposite (MWCNTs-Zn NPs) investigated for the detection of an agricultural pathogen i.e. Chili leaf curl betasatellite (ChLCB). Atomic force microscope analyses revealed the presence of multiwalled carbon nanotubes (MWCNTs) having a diameter of 50–100nm with zinc nanoparticles (Zn-NPs) of 25–500nm. In this system, these bunches of Zn-NPs anchored along the whole lengths of MWCNTs were used for the immobilization of probe DNA strands. The electrochemical performance of DNA biosensor was assessed in the absence and presence of the complementary DNA during cyclic and differential pulse voltammetry scans. Target binding events occurring on the interface surface patterned with single-stranded DNA was quantitatively translated into electrochemical signals due to hybridization process. In the presence of complementary target DNA, as the result of duplex formation, there was a decrease in the peak current from 1.89×10−04 to 5.84×10−05A. The specificity of this electrochemical DNA biosensor was found to be three times as compared to non-complementary DNA. This material structuring technique can be extended to design interfaces for the recognition of the other plant viruses and biomolecules.

The Genetic Heterogeneity among Different Mouse Strains Impacts the Lung Injury Potential of Multiwalled Carbon Nanotubes

Genetic variation constitutes an important variable impacting the susceptibility to inhalable toxic substances and air pollutants, as reflected by epidemiological studies in humans and differences among animal strains. While multiwalled carbon nanotubes (MWCNTs) are capable of causing lung fibrosis in rodents, it is unclear to what extent the genetic variation in different mouse strains influence the outcome. Four inbred mouse strains, including C57Bl/6, Balb/c, NOD/ShiLtJ, and A/J, to test the pro-fibrogenic effects of a library of MWCNTs in vitro and in vivo are chosen. Ex vivo analysis of IL-1β production in bone marrow-derived macrophages (BMDMs) as molecular initiating event (MIE) is performed. The order of cytokine production (Balb/c > A/J > C57Bl/6 > NOD/ShiLtJ) in BMDMs is also duplicated during assessment of IL-1β production in the bronchoalveolar lavage fluid of the same mouse strains 40 h after oropharyngeal instillation of a representative MWCNT. Animal test after 21 d also confirms a similar hierarchy in TGF-β1 production and collagen deposition in the lung. Statistical analysis confirms a correlation between IL-1β production in BMDM and the lung fibrosis. All considered, these data demonstrate that genetic background indeed plays a major role in determining the pro-fibrogenic response to MWCNTs in the lung.

Evaluation of Fibrogenic Potential of Industrial Multi-Walled Carbon Nanotubes in Acute Aspiration Experiment

Local inflammatory response in the lungs and fi brogenic potential of multi-walled carbon nanotubes were studied in an acute aspiration experiment in mice. The doses were chosen based on the concentration of nanotubes in the air at a workplace of the company-producer. ELISA, fl ow cytometry, enhanced darkfield microscopy, and histological examination showed that multi-walled carbon nanotubes induced local inflammation, oxidative stress, and connective tissue growth (fibrosis). Serum levels of TGF-β1 and osteopontin proteins can serve as potential exposure biomarkers.

Electrokinetic potential of multilayer carbon nanotubes in aqueous solutions of electrolytes and surfactants

The effect of electrolytes with single-, double- and triple-charged counterions, as well as cationic (cetyltrimethylammonium bromide) and anionic (sodium dodecyl sulfate) surfactants, on the electrokinetic potential of multiwall carbon nanotubes prepared via catalytic pyrolysis of propylene in a gas phase according to the CCVD technology has been studied. It has been shown that the influence of different electrolytes on the electrophoretic mobility of the nanotubes does not differ essentially from their effect on the behavior of well-studied inorganic dispersed particles; i.e., the dependence of the absolute values of the ζ-potential on the concentration of a 1: 1 electrolyte passes through a maximum and the introduction of double-charged counterions dramatically reduces the ζ-potential, while the addition of triple-charged cations and a cationic surfactant causes charge reversal of the nanotube surface. The adsorption of sodium dodecyl sulfate in a neutral medium increases the negative ζ values; this effect evens out in the presence of an alkali due to a rise in the electrostatic repulsion between surfactant anions and nanotube surface, which bears a high negative charge resulting from the dissociation of surface functional groups.