Enzymatic biosensor based on entrapment of d-amino acid oxidase on gold nanofilm/MWCNTs nanocomposite modified glassy carbon electrode by sol-gel network: Analytical applications for d-alanine in human serum

Sensing and determination of d-alanine is studied by using an enzymatic biosensor which was constructed on the basis of d-amino acid oxidase (DAAO) immobilization by sol-gel film onto glassy carbon electrode surface modified with nanocomposite of gold nanofilm (Au-NF) and multiwalled carbon nanotubes (MWCNTs). The Au-NF/MWCNT nanocomposite was prepared by applying the potentiostatic technique for electrodeposition of Au-NF on the MWCNT immobilized on glassy carbon electrode surface. The modified electrode is investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry(CV) techniques. The linear sweep voltammetry was used for determination of d-alanine and the results showed an excellent linear relationship between biosensor response and d-alanine concentration ranging from 0.25μM to 4.5μM with correction coefficient of 0.999 (n=20). Detection limit for the fabricated sensor was calculated about 20nM (for S/N=3) and sensitivity was about 56.1μAμM^-1cm^-2. The developed biosensor exhibited rapid and accurate response to d-alanine, a good stability (4 weeks) and an average recovery of 98.9% in human serum samples.

Carbon nanotube amendment for treating dichlorodiphenyltrichloroethane and hexachlorocyclohexane remaining in Dong-ting Lake sediment - An implication for in-situ remediation

Organochlorine pesticides (OCPs) were largely sprayed on the floodplain soils before the project of Returning Farmland to Lake in China, which caused contamination of sediment in Dong-ting Lake with dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) and posed threats to human health and other organisms. In this study, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) at different concentrations of 0.058, 0.145 and 0.29wt% were used to manage residual DDTs and HCHs in Dong-ting Lake sediment. The efficacy was assessed by DDTs and HCHs deriving from the aqueous equilibrium experiment and uptake in semipermeable membrane devices (SPMDs). Desorption experiment and the quiescent flux experiment were conducted as well. The results showed that DDTs and HCHs were released from sediment. The p, p'-DDT was desorbed less readily than its metabolites and similarly α-HCH was desorbed less easily than other HCH isomers from sediment. Carbon nanotubes had great effects on treating DDTs and HCHs. The effectiveness of carbon nanotube amendment was dependent on type, dose and sediment-sorbent contact time In addition, carbon nanotubes being sprinkled on the surface of sediment as a cap and being injected into sediment as a mixture were considered as two effective ways to prevent DDTs and HCHs being released from sediment. Carbon nanotubes can be potentially useful as sorbents in in-situ remediation.

Single-Wall Carbon Nanotube Doping in Lead-Acid Batteries: A New Horizon

The addition of single-wall carbon nanotubes (SWCNT) to lead-acid battery electrodes is the most efficient suppresser of uncontrolled sulfation processes. Due to the cost of SWCNT, we studied the optimization loading of SWCNT in lead-acid battery electrodes. We optimized the SWCNT loading concentrations in both the positive and negative plates, separately. Loadings of 0.01% and 0.001% in the positive and negative active masses were studied, respectively. Two volts of lead-acid laboratory cells with sulfuric acid, containing silica gel-type electrolytes, were cycled in a 25% and 50% depth-of-discharge (DOD) cycling with a charging rate of C and 2C, respectively, and discharge rates of C/2 and C, respectively. All tests successfully demonstrated an excellent service life up to about 1700 and 1400 cycles for 25% and 50% DOD operations, respectively, at a low loading level of SWCNT. This performance was compared with CNT-free cells and cells with a multiwall carbon nanotube (MWCNT) additive. The outstanding performance of the lead-acid cells with the SWCNT additive is due to the oxidative stability of the positive plates during charging and the efficient reduction in sulfation in both plates while forming conducting active-material matrices.

Effects of lipopolysaccharide, multiwalled carbon nantoubes, and the combination on lung alveolar epithelial cells

Multiwalled carbon nanotubes (MWCNT) have been shown to induce lung fibrosis in animal models, however the underlying molecular factors/mechanisms are still unclear. In this study, we investigated the effects of lipopolysaccharide (LPS), MWCNT, and the combination of LPS and MWCNT on the expression of matrix metalloproteinase-9 and metalloproteinase-12 (MMP-9, MMP-12), collagen 3A1 (Col3A1), and transforming growth factor beta (TGFβ) in alveolar epithelial A549 cells. MMPs are proteinases that degrade extracellular matrix and play a role in lung fibrosis. A549 cells were exposed to LPS (1 ng/mL), MWCNT (20 μg/mL), and the combination and analyzed for paracellular permeability, TGFβ, Col3A1, MMP-9, MMP-12, NF-κB activation, and cell migration by real-time PCR and immunofluorescence. LPS, the combination of LPS and MWCNT, and MWCNT only at the highest tested dose induced blue dextran extravasation. LPS and MWCNT increased the expression of TGFβ and its downstream target gene Col3A, and MMP-9 and MMP-12 mRNA. MWCNT potently induced cell migration toward wound healing, whereas LPS slightly induced cell migration. Both, LPS and MWCNT, induced NF-κB nuclear translocation. Our results indicate that MWCNT activated alveolar epithelial cells to promote fibrogenesis, and that LPS differentially primes molecular factors involved in lung remodeling. These findings suggest a role of alveolar epithelial cells in fibrogenesis and also may aid in the design and development of tests for screening of fibrogenic agents. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 445-455, 2017.

Phagolysosome acidification is required for silica and engineered nanoparticle-induced lysosome membrane permeabilization and resultant NLRP3 inflammasome activity

NLRP3 inflammasome activation occurs in response to hazardous particle exposures and is critical for the development of particle-induced lung disease. Mechanisms of Lysosome Membrane Permeabilization (LMP), a central pathway for activation of the NLRP3 inflammasome by inhaled particles, are not fully understood. We demonstrate that the lysosomal vATPases inhibitor Bafilomycin A1 blocked LMP in vitro and ex vivo in primary murine macrophages following exposure to silica, multi-walled carbon nanotubes, and titanium nanobelts. Bafilomycin A1 treatment of particle-exposed macrophages also resulted in decreased active cathepsin L in the cytosol, a surrogate measure for leaked cathepsin B, which was associated with less NLRP3 inflammasome activity. Silica-induced LMP was partially dependent upon lysosomal cathepsins B and L, whereas nanoparticle-induced LMP occurred independent of cathepsin activity. Furthermore, inhibition of lysosomal cathepsin activity with CA-074-Me decreased the release of High Mobility Group Box 1. Together, these data support the notion that lysosome acidification is a prerequisite for particle-induced LMP, and the resultant leak of lysosome cathepsins is a primary regulator of ongoing NLRP3 inflammasome activity and release of HMGB1.

Differential crosstalk between global DNA methylation and metabolomics associated with cell type specific stress response by pristine and functionalized MWCNT

The present study endeavored to evaluate the comprehensive mechanisms of MWCNT-induced toxicity with particular emphasis on understanding cell specificity in relation to surface functionalization of MWCNT. Following treatment with differentially functionalized (hydroxylation/carboxylation) MWCNT on human bronchial epithelial (BEAS-2B) and human hepatoma (HepG2) cell lines, intracellular uptake, various toxicological end points, global metabolomics profiling and DNA methylation were evaluated. Herein, the comparative in vitro studies ascertained that surface functionalization diminished the toxic potentiality of MWCNT in respect of their pristine counterpart. The surface enhanced Raman scattering with dark-field microscopy attested the intracellular uptake of functionalized-MWCNT, but not the pristine one. The MWCNT's exposure caused alterations in stress responses (oxidative stress, inflammation, profibrosis, DNA damage-repair), differential mode of gene expressions, global metabolomics and DNA methylation status (DNMT3B dependent hypo-methylation in BEAS-2B cells and hyper-methylation in HepG2 cells) in a cell type specific and surface functionalization dependent manner. The alterations in particular metabolites (choline, betaine, succinate etc.) and distinct DNA methylation crosstalk patterns are the possible underlying mechanisms of differential mode of gene expressions and cell type specificity of MWCNT. This study provides preliminary evidence of epigenetic modifications and global metabolomics profiling which might be translated for risk assessment of MWCNT.

Lung carcinogenicity of inhaled multi-walled carbon nanotube in rats

BACKGROUND

Multi-walled carbon nanotubes (MWCNTs) constitute one of the most promising types of nanomaterials in industry today. With their increasing use, the potential toxicity and carcinogenicity of MWCNT needs to be evaluated in bioassay studies using rodents. Since humans are mainly exposed to MWCNT by inhalation, we performed a 104-week carcinogenicity study using whole-body inhalation exposure chambers with a fibrous straight type of MWCNT at concentrations of 0, 0.02, 0.2, and 2 mg/m3 using male and female F344 rats.

RESULTS

Lung carcinomas, mainly bronchiolo-alveolar carcinoma, and combined carcinomas and adenomas were significantly increased in males exposed to 0.2 and 2 mg/m3 MWNT-7 and in females exposed to 2 mg/m3 MWNT-7 compared to the clean air control group. However, no development of pleural mesothelioma was observed. Concentration-dependent toxic effects in the lung such as epithelial hyperplasia, granulomatous change, localized fibrosis, and alteration in BALF parameters were found in MWNT-7 treatment groups of both sexes. There were no MWNT-7-specific macroscopic findings in the other organs, including the pleura and peritoneum. Absolute and relative lung weights were significantly elevated in male rats exposed to 0.2 and 2 mg/m3 MWNT-7 and in all exposed female groups. The lung burdens of MWNT-7 were clearly increased in a concentration-dependent as well as a duration-dependent manner.

CONCLUSION

There is clear evidence that MWNT-7 is carcinogenic to the lungs of male and female F344 rats, however no plural mesothelioma was observed.

Tuning the Shape Anisotropy and Electromagnetic Screening Ability of Ultrahigh Magnetic Polymer and Surfactant-Capped FeCo Nanorods and Nanocubes in Soft Conducting Composites

Herein, we demonstrate that very high electromagnetic (EM) shielding efficiency can be achieved by dispersing nanoengineered FeCo anisometric nanostructures in a poly(vinylidene difluoride) matrix in the presence of conductive nanofillers (multiwall carbon nanotubes, MWCNTs). The FeCo nanorods (∼800 nm) and nanocubes (∼100 nm) were fabricated by a facile surfactant and polymer-assisted one-pot borohydride reduction method. The growth mechanism depicted a two-directional growth for cubes, whereas for nanorods, a unidirectional growth pattern across the (110) plane was evident. A total shielding effectiveness (SE_T) of -44 dB at 18 GHz was achieved for a particular combination of FeCo nanorods and MWCNT, and for nanocube-based composites, it was found to be -39 dB at 18 GHz. It was observed from zero field cooled-field cooled curves that the samples displayed room temperature ferromagnetism. An excellent correlation between high aspect ratio FeCo nanorod and superior EM absorption (89%) was explored, pertaining to the fact that nanorods possessed higher magnetic saturation (177.1 emu/g) and coercivity (550 Oe) in contrast to the nanocubes with similar composition. Furthermore, theoretical insight into the mechanism revealed a high degree of interface scattering between conductive MWCNT and magnetic loss components, giving rise to an excellent synergy between magnetic and dielectric parts.

Defect density in multiwalled carbon nanotubes influences ovalbumin adsorption and promotes macrophage activation and CD4(+) T-cell proliferation

Carbon nanotubes (CNTs) are of great interest for the development of drugs and vaccines due to their unique physicochemical properties. The high surface area to volume ratio and delocalized pi-electron cloud of CNTs promote binding of proteins to the surface forming a protein corona. This unique feature of CNTs has been recognized for potential delivery of antigens for strong and long-lasting antigen-specific immune responses. Based on an earlier study that demonstrated increased protein binding, we propose that carboxylated multiwalled CNTs (MWCNTs) can function as an improved carrier to deliver antigens such as ovalbumin (OVA). To test this hypothesis, we coated carboxylated MWCNTs with OVA and measured uptake and activation of antigen-presenting cells (macrophages) and their ability to stimulate CD4⁺ T-cell proliferation. We employed two types of carboxylated MWCNTs with different surface areas and defects (MWCNT-2 and MWCNT-30). MWCNT-2 and MWCNT-30 have surface areas of ~215 m²/g and 94 m²/g, respectively. The ratios of D- to G-band areas (I_D/I_G) were 0.97 and 1.37 for MWCNT-2 and MWCNT-30, respectively, samples showing that MWCNT-30 contained more defects. The increase in defects in MWCNT-30 led to increased binding of OVA as compared to MWCNT-2 (1,066±182 μg/mL vs 582±41 μg/mL, respectively). Both types of MWCNTs, along with MWCNT–OVA complexes, showed no observable toxicity to bone-marrow-derived macrophages up to 5 days. Surprisingly, we found that MWCNT–OVA complex significantly increased the expression of major histocompatibility complex class II on macrophages and production of pro-inflammatory cytokines (tumor necrosis factor-α and interleukin 6), while MWCNTs without OVA protein corona did not. The coculture of MWCNT–OVA-complex-treated macrophages and OVA-specific CD4⁺ T-cells isolated from OT-II mice demonstrated robust proliferation of CD4⁺ T-cells. This study provides strong evidence for a role for defects in carboxylated MWCNTs and their use in the efficient delivery of antigens for the development of next-generation vaccines.

The cardiac effects of carbon nanotubes in rat

INTRODUCTION

Carbon nanotubes (CNTs) are novel candidates in nanotechnology with a variety of increasing applications in medicine and biology. Therefore the investigation of nanomaterials' biocompatibility can be an important topic. The aim of present study was to investigate the CNTs impact on cardiac heart rate among rats.

METHODS

Electrocardiogram (ECG) signals were recorded before and after injection of CNTs on a group with six rats. The heart rate variability (HRV) analysis was used for signals analysis. The rhythm-to-rhythm (RR) intervals in HRV method were computed and features of signals in time and frequency domains were extracted before and after injection.

RESULTS

RESULTS of the HRV analysis showed that CNTs increased the heart rate but generally these nanomaterials did not cause serious problem in autonomic nervous system (ANS) normal activities.

CONCLUSION

Injection of CNTs in rats resulted in increase of heart rate. The reason of phenomenon is that multiwall CNTs may block potassium channels. The suppressed and inhibited IK and potassium channels lead to increase of heart rate.

Fibrosis biomarkers in workers exposed to MWCNTs

Multi-walled carbon nanotubes (MWCNT) with their unique physico-chemical properties offer numerous technological advantages and are projected to drive the next generation of manufacturing growth. As MWCNT have already found utility in different industries including construction, engineering, energy production, space exploration and biomedicine, large quantities of MWCNT may reach the environment and inadvertently lead to human exposure. This necessitates the urgent assessment of their potential health effects in humans. The current study was carried out at NanotechCenter Ltd. Enterprise (Tambov, Russia) where large-scale manufacturing of MWCNT along with relatively high occupational exposure levels was reported. The goal of this small cross-sectional study was to evaluate potential biomarkers during occupational exposure to MWCNT. All air samples were collected at the workplaces from both specific areas and personal breathing zones using filter-based devices to quantitate elemental carbon and perform particle analysis by TEM. Biological fluids of nasal lavage, induced sputum and blood serum were obtained from MWCNT-exposed and non-exposed workers for assessment of inflammatory and fibrotic markers. It was found that exposure to MWCNTs caused significant increase in IL-1β, IL6, TNF-α, inflammatory cytokines and KL-6, a serological biomarker for interstitial lung disease in collected sputum samples. Moreover, the level of TGF-β1 was increased in serum obtained from young exposed workers. Overall, the results from this study revealed accumulation of inflammatory and fibrotic biomarkers in biofluids of workers manufacturing MWCNTs. Therefore, the biomarkers analyzed should be considered for the assessment of health effects of occupational exposure to MWCNT in cross-sectional epidemiological studies.

Enhancement of Carbon Nanotube Particle Distribution in PPS/PEEK/Carbon Nanotube Ternary Composites with Sausage-Like Structure

Carbon nanomaterial particles were selectively distributed in an incompatible and high-melting-temperature polymer blend interface, or in a particular phase, to obtain conductive composites. The composite products revealed poor morphology stability and mechanical performance due to processing several times. Poly(phenylene sulfide) (PPS) and poly(ether ether ketone) (PEEK) polymers with large differences of processing temperatures were selected as blend components to obtain a compatible blend. PPS/PEEK/multi-walled carbon nanotube (MWCNT) ternary nanocomposites were prepared using a controlled melt blending process. The composite samples with similar sausage-like structures of PEEK, as a dispersed phase, promote MWCNT to maximize concentration distribution in the PPS continuous phase. As a result, the theoretical percolation threshold of the composite reduced to 0.347 wt %. Moreover, the conductivity of the composite remained stable even after processing several times. CNTs revealed a particular effect when distributed selectively in this kind of system: it can enhance the dispersion of phases and also provide conductivity to the blend at small CNT contents, which can provide more useful ideas for the development of high-melting-temperature and antistatic or conductive plastic materials.

Vitamin E TPGS conjugated carbon nanotubes improved efficacy of docetaxel with safety for lung cancer treatment

The aim of this work was to develop multi-walled carbon nanotubes (MWCNT), which were coated or covalently conjugated with d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS), and loaded docetaxel as a model drug for effective treatment to lung cancer in comparison with the commercial docetaxel injection (Docel™). The human lung cancer cells (A549 cells) were employed as an in-vitro model to access cellular uptake, cytotoxicity, cellular apoptosis, cell cycle analysis, and reactive oxygen species (ROS) study of the docetaxel/coumarin-6 loaded MWCNT. The safety of MWCNT formulations were studied by the measurements of alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and total protein levels in bronchoalveolar lavage (BAL) fluid of rats after the treatments. The IC50 values demonstrated that the TPGS conjugated MWCNT could be 80 folds more effective than Docel™ after 24h treatment with the A549 cells. Flow cytometry analysis confirmed that cancerous cells were appeared significantly (P<0.05) in the sub G1 phase for TPGS conjugated MWCNT. Results of TPGS conjugated MWCNT have showed better efficacy with safety than non-coated or TPGS coated MWCNT and Docel™.

Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode

This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents.

Solution-Processed Gas Sensors Employing SnO2 Quantum Dot/MWCNT Nanocomposites

Solution-processed SnO2 colloidal quantum dots (CQDs) have emerged as an important new class of gas-sensing materials due to their potential for low-cost and high-throughput fabrication. Here we employed the design strategy based on the synergetic effect from highly sensitive SnO2 CQDs and excellent conductive properties of multiwalled carbon nanotubes (MWCNTs) to overcome the transport barrier in CQD gas sensors. The attachment and coverage of SnO2 CQDs on the MWCNT surfaces were achieved by simply mixing the presynthesized SnO2 CQDs and MWCNTs at room temperature. Compared to the pristine SnO2 CQDs, the sensor based on SnO2 quantum dot/MWCNT nanocomposites exhibited a higher response upon exposure to H2S, and the response toward 50 ppm of H2S at 70 °C was 108 with the response and recovery time being 23 and 44 s. Because of the favorable energy band alignment, the MWCNTs can serve as the acceptor of the electrons that are injected from H2S into SnO2 quantum dots in addition to the charge transport highway to direct the electron flow to the electrode, thereby enhancing the sensor response. Our research results open an easy pathway for developing highly sensitive and low-cost gas sensors.

mRNAs and miRNAs in whole blood associated with lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma after multi-walled carbon nanotube inhalation exposure in mice

Inhalation exposure to multi-walled carbon nanotubes (MWCNT) in mice results in inflammation, fibrosis and the promotion of lung adenocarcinoma; however, the molecular basis behind these pathologies is unknown. This study determined global mRNA and miRNA profiles in whole blood from mice exposed by inhalation to MWCNT that correlated with the presence of lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma. Six-week-old, male, B6C3F1 mice received a single intraperitoneal injection of either the DNA-damaging agent methylcholanthrene (MCA, 10 µg g(-1) body weight) or vehicle (corn oil). One week after injections, mice were exposed by inhalation to MWCNT (5 mg m(-3), 5 hours per day, 5 days per week) or filtered air (control) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for the development of pathological changes in the lung, and whole blood was collected and analyzed using microarray analysis for global mRNA and miRNA expression. Numerous mRNAs and miRNAs in the blood were significantly up- or down-regulated in animals developing pathological changes in the lung after MCA/corn oil administration followed by MWCNT/air inhalation, including fcrl5 and miR-122-5p in the presence of hyperplasia, mthfd2 and miR-206-3p in the presence of fibrosis, fam178a and miR-130a-3p in the presence of bronchiolo-alveolar adenoma, and il7r and miR-210-3p in the presence of bronchiolo-alveolar adenocarcinoma, among others. The changes in miRNA and mRNA expression, and their respective regulatory networks, identified in this study may potentially serve as blood biomarkers for MWCNT-induced lung pathological changes.

Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures

l-lactate is an essential metabolite present in embryonic cell culture. Changes of this important metabolite during the growth of human embryo reflect the quality and viability of the embryo. In this study, we report a sensitive, stable, and easily manufactured electrochemical biosensor for the detection of lactate within embryonic cell cultures media. Screen-printed disposable electrodes are used as electrochemical sensing platforms for the miniaturization of the lactate biosensor. Chitosan/multi walled carbon nanotubes composite have been employed for the enzymatic immobilization of the lactate oxidase enzyme. This novel electrochemical lactate biosensor analytical efficacy is explored towards the sensing of lactate in model (buffer) solutions and is found to exhibit a linear response towards lactate over the concentration range of 30.4 and 243.9 µM in phosphate buffer solution, with a corresponding limit of detection (based on 3-sigma) of 22.6 µM and exhibits a sensitivity of 3417 ± 131 µAM(-1) according to the reproducibility study. These novel electrochemical lactate biosensors exhibit a high reproducibility, with a relative standard deviation of less than 3.8% and an enzymatic response over 82% after 5 months stored at 4 °C. Furthermore, high performance liquid chromatography technique has been utilized to independently validate the electrochemical lactate biosensor for the determination of lactate in a commercial embryonic cell culture medium providing excellent agreement between the two analytical protocols.

Alterations in DNA methylation corresponding with lung inflammation and as a biomarker for disease development after MWCNT exposure

Use of multi-walled carbon nanotubes (MWCNT) is growing which increases occupational exposures to these materials. Their toxic potential makes it important to have an in-depth understanding of the inflammation and disease that develops due to exposure. Epigenetics is one area of interest that has been quickly developing to assess disease processes due to its ability to change gene expression and thus the lung environment after exposure. In this study, promoter methylation of inflammatory genes (IFN-γ and TNF-α) was measured after MWCNT exposure using the pyrosequencing assay and found to correlate with initial cytokine production. In addition, methylation of a gene involved in tissue fibrosis (Thy-1) was also altered in a way that matched collagen deposition. In addition to using epigenetics to better understand disease processes, it has also been used as a biomarker of exposure and disease. In this study, global methylation was determined in the lung to ascertain whether MWCNT alter global methylation at the site of exposure and if those alterations coincide with disease development. Then, global methylation levels were determined in the blood to ascertain whether global methylation could be used as a biomarker of exposure in a more easily accessible tissue. Using the LuUminometric Methylation Assay (LUMA) and 5-Methylcytosine (5-mC) Quantification assay, we found that MWCNT lead to DNA hypomethylation in the lung and blood, which coincided with disease development. This study provides initial data showing that alterations in gene-specific methylation correspond with an inflammatory response to MWCNT exposure. In addition, global DNA methylation in the lung and blood coincides with MWCNT-induced disease development, suggesting its potential as a biomarker of both exposure and disease development.

An Effective Electrical Throughput from PANI Supplement ZnS Nanorods and PDMS-Based Flexible Piezoelectric Nanogenerator for Power up Portable Electronic Devices: An Alternative of MWCNT Filler

We demonstrate the requirement of electrical poling can be avoided in flexible piezoelectric nanogenerators (FPNGs) made of low-temperature hydrothermally grown wurtzite zinc sulfide nanorods (ZnS-NRs) blended with polydimethylsiloxane (PDMS). It has been found that conductive fillers, such as polyaniline (PANI) and multiwall carbon nanotubes (MWCNTs), can subsequently improve the overall performance of FPNG. A large electrical throughput (open circuit voltage ∼35 V with power density ∼2.43 μW/cm(3)) from PANI supplement added nanogenerator (PZP-FPNG) indicates that it is an effective means to replace the MWCNTs filler. The time constant (τ) estimated from the transient response of the capacitor charging curves signifying that the FPNGs are very much capable to charge the capacitors in very short time span (e.g., 3 V is accomplished in 50 s) and thus expected to be perfectly suitable in portable, wearable and flexible electronics devices. We demonstrate that FPNG can instantly lit up several commercial Light Emitting Diodes (LEDs) (15 red, 25 green, and 55 blue, individually) and power up several portable electronic gadgets, for example, wrist watch, calculator, and LCD screen. Thus, a realization of potential use of PANI in low-temperature-synthesized ZnS-NRs comprising piezoelectric based nanogenerator fabrication is experimentally verified so as to acquire a potential impact in sustainable energy applications. Beside this, wireless piezoelectric signal detection possibility is also worked out where a concept of self-powered smart sensor is introduced.

A carbon nanotube/poly [Ni-(Protoporphyrin IX)] composite for amperometric detection of long chain aliphatic amines

Poly [Ni-Protoporphyrin] film (pNiPP), containing multiwall carbon nanotubes (MWCNT) was used to cover a glassy carbon electrode. The hybrid material (pNiPP/MWCNT) successfully combines the permselectivity of pNiPP with the high conductivity of MWCNT. The modified electrode was used to perform amperometric detection of long chain aliphatic amines (LCAA) in order to prevent the passivation effect of the aliphatic chain. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that the pNiPP/MWCNT facilitates the electron transfer reaction. The charge transfer resistance (Rct) values were significantly lower by up to one order of magnitude compared to the bare electrode. Differential pulse polarography (DPP) showed a marked decrease of the overpotential generated by the aliphatic chain. The calibration of the amperometric peak area vs. concentrations of derivatized LCAA exhibits a linear response within the range of 0.018 and 28 μM and correlation coefficient (R(2)) higher than 0.999 (n=5). The quantitation limit of the pNiPP/MWCNT electrode is about 400 times lower than the UV-visible detection. RSD of 7.2%, 5.8%, 2.5% and 2.3% was obtained for concentrations of 0.028, 0.28, 2.8 and 28 μM of ferrocenyl octadecylamine. A solution of sphingosine, 0.23 μM, was exclusively detected with HPLC-ECD with pNiPP/MWCNT electrode.

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 (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) 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 (20×2×2 mm(3)) 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 0.5 wt%.

Quasi-QSAR for mutagenic potential of multi-walled carbon-nanotubes

Available on the Internet, the CORAL software (http://www.insilico.eu/coral) has been used to build up quasi-quantitative structure-activity relationships (quasi-QSAR) for prediction of mutagenic potential of multi-walled carbon-nanotubes (MWCNTs). In contrast with the previous models built up by CORAL which were based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) the quasi-QSARs based on the representation of conditions (not on the molecular structure) such as concentration, presence (absence) S9 mix, the using (or without the using) of preincubation were encoded by so-called quasi-SMILES. The statistical characteristics of these models (quasi-QSARs) for three random splits into the visible training set and test set and invisible validation set are the following: (i) split 1: n=13, r(2)=0.8037, q(2)=0.7260, s=0.033, F=45 (training set); n=5, r(2)=0.9102, s=0.071 (test set); n=6, r(2)=0.7627, s=0.044 (validation set); (ii) split 2: n=13, r(2)=0.6446, q(2)=0.4733, s=0.045, F=20 (training set); n=5, r(2)=0.6785, s=0.054 (test set); n=6, r(2)=0.9593, s=0.032 (validation set); and (iii) n=14, r(2)=0.8087, q(2)=0.6975, s=0.026, F=51 (training set); n=5, r(2)=0.9453, s=0.074 (test set); n=5, r(2)=0.8951, s=0.052 (validation set).

MWCNT uptake in Allium cepa root cells induces cytotoxic and genotoxic responses and results in DNA hyper-methylation

Advances in nanotechnology have led to the large-scale production of nanoparticles, which, in turn, increases the chances of environmental exposure. While humans (consumers/workers) are primarily at risk of being exposed to the adverse effect of nanoparticles, the effect on plants and other components of the environment cannot be ignored. The present work investigates the cytotoxic, genotoxic, and epigenetic (DNA methylation) effect of MWCNT on the plant system- Allium cepa. MWCNT uptake in root cells significantly altered cellular morphology. Membrane integrity and mitochondrial function were also compromised. The nanotubes induced significant DNA damage, micronucleus formation and chromosome aberration. DNA laddering assay revealed the formation of internucleosomal fragments, which is indicative of apoptotic cell death. This finding was confirmed by an accumulation of cells in the sub-G0 phase of the cell cycle. An increase in CpG methylation was observed using the isoschizomers MspI/HpaII. HPLC analysis of DNA samples revealed a significant increase in the levels of 5-methyl-deoxy-cytidine (5mdC). These results confirm the cyto-genotoxic effect of MWCNT in the plant system and simultaneously highlight the importance of this epigenetic study in nanoparticle toxicity.

One time nose-only inhalation of MWCNTs: Exploring the mechanism of toxicity by intermittent sacrifice in Wistar rats

We have investigated the time-dependent effect of multi-walled carbon nanotubes (MWCNTs) in rats upon single inhalation exposure followed by intermittent sacrifice. The effects were monitored by analyzing the bronchoalveolar lavage fluid (BALF) and histopathological analysis. Cell count, neutrophils, lymphocytes, lactate dehydrogenase, alkaline phosphatase, protein and cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 4 (IL-4)) were significantly increased, while cell viability and alveolar macrophage count significantly decreased in the BALF of MWCNT-treated rats on day 1, day 7 and day 14 post-exposure, when compared to control rats. Histopathological analysis revealed inflammation, fibrosis and granuloma in the lungs of MWCNTs-treated rats on day 7 and day 14 post-exposure. We interpret that MWCNT induces inflammation, fibrosis and granuloma characterized by progressive elevation of TNF-α and IL-4. Histopathological studies further support our view and reveal the distribution of MWCNT in lungs and tracheobronchial lymph nodes (TBLN). We conclude that MWCNT-induced pulmonary toxicity is considerable even on single exposure.

Stiff diamond/buckypaper carbon hybrids

Given the specific properties of each carbon allotrope such as high electrical/thermal conductivity of multiwall carbon nanotubes (MWCNT) and extreme hardness and high inertness of nanocrystalline diamond (NCD), the integration of both carbon phases is highly desirable. Therefore, in the present work, buckypapers were produced from MWCNT suspensions and were used as free-standing substrates to be coated with NCD by microwave plasma chemical vapor deposition (MPCVD). The integration of both allotropes was successfully achieved, the CNTs being preserved after diamond growth as confirmed by μ-Raman spectroscopy and scanning electron microscopy (SEM). Additionally, a good linkage was observed, the CNTs remaining embedded within the NCD matrix, thus reinforcing the interface of the resulting hybrid structure. This was corroborated by bending tests in a modified nanohardness tester. The increase of the Young's modulus from 0.3 to 300 GPa after NCD growth enables the use of this material in a wide range of applications including microelectromechanical systems (MEMS). Additionally, a highly anisotropic electrical resistivity behavior was confirmed: low in-plane values were found for the CNT layer (1.39 × 10(-2) Ω.cm), while high transverse ones were measured for both the NCD coated and uncoated CNT buckypapers (8.13 × 10(5) and 6.18 × 10(2) Ω.cm, respectively).