Types Of Carbon Nanoparticles Research Articles

Photoporation Using Carbon Nanotubes for Intracellular Delivery of Molecules and Its Relationship to Photoacoustic Pressure.

Exposure of carbon-black (CB) nanoparticles to near-infrared nanosecond-pulsed laser energy can cause efficient intracellular delivery of molecules by photoporation. Here, cellular bioeffects of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) are compared to those of CB nanoparticles. In DU145 prostate-cancer cells, photoporation using CB nanoparticles transitions from (i) cells with molecular uptake to (ii) nonviable cells to (iii) fragmented cells with increasing laser fluence, as seen previously. In contrast, photoporation with MWCNTs causes uptake and, at higher fluence, fragmentation, but does not generate nonviable cells, and SWCNTs show little evidence of bioeffects, except at extreme laser conditions, which generate nonviable cells and fragmentation, but no significant uptake. These different behaviors cannot be explained by photoacoustic pressure output from the particles. All particle types emit a single, ≈100 ns, mostly positive-pressure pulse that increases in amplitude with laser fluence. Different particle types emit different peak pressures, which are highest for SWCNTs, followed by CB nanoparticles and then MWCNTs, which does not correlate with cellular bioeffects between different particle types. This study concludes that cellular bioeffects depend strongly on the type of carbon nanoparticle used during photoporation and that photoacoustic pressure is unlikely to play a direct mechanistic role in the observed bioeffects.

Theoretical Investigation of Anion-Radical States of Edge-Oxidized Carbon Model Clusters.

A set of flat carbon clusters and ultrashort carbon nanotubes in different anion-radical states was investigated by density functional theory and complete-active space self-consistent field methods. It was found that carbon nanoparticles with pervasively oxidized edges are extremely strong oxidants, and their ground states in catalytic studies should be considered as negatively charged rather than neutral, as it is traditionally done. Negative charging renders initially diamagnetic/semiconducting types of carbon nanoparticles into half-metallic, which can also be achieved by doping with transition metals.

Toxicity studies of six types of carbon nanoparticles in a chicken-embryo model.

In the present study, the toxicity of six different types of carbon nanoparticles (CNPs) was investigated using a chicken-embryo model. Fertilized chicken eggs were divided into the following treatment groups: placebo, diamond NPs, graphite NPs, pristine graphene, small graphene oxide, large graphene oxide, and reduced graphene oxide. Experimental solutions at a concentration of 500 μg/mL were administrated into the egg albumin. Gross pathology and the rate of survival were examined after 5, 10, 15, and 20 days of incubation. After 20 days of incubation, blood samples were collected and the weight of the body and organs measured. The relative ratio of embryo survival decreased after treatment all treatments except diamond NPs. There was no correlation between the rate of survival and the ζ-potential or the surface charge of the CNPs in solution. Body and organ weight, red blood-cell morphology, blood serum biochemical parameters, and oxidative damage in the liver did not differ among the groups. These results indicate that CNPs can remain in blood circulation without any major side effects, suggesting their potential applicability as vehicles for drug delivery or active compounds per se. However, there is a need for further investigation of their properties, which vary depending on production methods and surface functionalization.

The cluster architecture of carbon in polymer nanocomposites observed by impulse acoustic microscopy

The high‐resolution ultrasonic technique (impulse acoustic microscopy) was applied for observing the bulk microstructure of nanocomposites with various types of carbon nanoparticles as filler. It was shown that ultrasonic methods are excellent tools for studying nanoparticle distribution over the material bulk and for revealing probable nonuniformity. The acoustic microscopy technique allows for looking through the bulk microstructure of objects by means of layer‐by‐layer visualization and object cross‐sectional imaging. In composites based on dispersed micrometer‐sized particles of exfoliated graphite, the particle distribution over the composite material bulk was observed. In nanocomposites with various kinds of low‐dimensional carbon nanofillers, i.e., nanoflakes, nanoplatelets, and nanotubes, the technique allowed the cluster architecture of the nanoparticle distribution to be revealed. Contact conjugation of low‐dimensionality nanoparticles led to fractal clusters despite significant technological efforts for providing homogeneity to the nanocomposite materials and uniformity to their properties. A pronounced tendency to form micrometer‐sized fractal agglomerates was found for 2D carbon nanoparticles: nanoflakes and nanoplatelets. The impulse acoustic microscopy technique provides visualization of the agglomerate distribution over the nanocomposite material bulk. Another kind of nanoparticle distribution was observed with carbon nanotubes (CNTs). The latter formed CNT packings having different densities. Such regions were seen in acoustical images as small‐sized areas of various brightness.

Evolution of size distribution and morphology of carbon nanoparticles during ethylene pyrolysis

The effects of furnace temperature and residence time on particle size distributions (PSDs) of carbon black, which is a type of carbon nanoparticle, were studied with a scanning mobility particle sizer. Particles were classified according to their mobility diameters by a differential mobility analyzer, followed by thermophoretic sampling by scanning electron microscopy to investigate their carbon black morphologies. PSDs were power-law distributions at short residence times and log-normal distributions at long residence times; these distributions indicate that agglomeration increases with increasing residence time. In addition, few 2.5-nm-sized particles existed above 1540 ± 40 K, while the critical size was 3 nm at 1350 ± 40 K. This finding indicates that the critical size of nuclei changes with temperature. At high temperatures of 1776 and 1676 K, the 100 and 180-nm-sized particles, whose primary particles kept their shape, had very complex morphologies. In contrast, at low temperature at 1570 K, the morphologies of 100 and 180-nm-sized aggregates are relativity simple, and primary particles nearly fused together in those aggregates. These observations indicate that the nucleation rate and fusing behavior change with temperature.

Rheological characteristics of different carbon nanoparticles in cholesteric mesogen dispersions as lubricant coolant additives

The effect of two types of carbon nanoparticles, i.e., shungite carbon (SC) and multiwalled carbon nanotubes (MWCNTs), on the mesomorphic and rheological properties of cholesteric mesogen in the concentration range of 0.005–0.04 wt % has been reported. The main physical parameters for tribological applications, such as phase transition temperature, viscosity, elastic modulus G', loss modulus G'', and complex viscosity η*, have been studied. The preference of using SC as a lubricating coolant additive component has been shown in the comparison with MWCNTs.

Comparative studies of singlet oxygen generation by fullerenes and single- and multilayer carbon nanotubes in aqueous suspensions

Singlet oxygen generation is studied in three types of carbon nanoparticles (C60 fullerene and single- and multilayer carbon nanotubes in the form of aqueous suspensions obtained by sonication) upon their irradiation by continuous-wave broadband visible radiation of light-emitting diodes.

Comparative studies of singlet oxygen generation by fullerenes and single- and multilayer carbon nanotubes in the form of solid-phase film coatings

Four types of carbon nanoparticles: C60 fullerene (crystalline and amorphized) and single- and multilayer carbon nanotubes were studied in the form of solid-phase film coatings for the purpose of obtaining singlet oxygen generation in the process of irradiation of these materials by continuous-wave broadband light-emitting diodes in the visible region spectra and by a monopulse 532-nm neodymium laser.

Detailed kinetic analysis of the impact of nucleation behavior and particle size distribution on the configurations of carbon black

The impact of nucleation behavior and particle size distribution on the morphology of carbon black, which is a type of carbon nanoparticle, is investigated using a fixed sectional approach by applying the detailed chemical kinetic reaction for our previous experimental work: the pyrolysis of benzene in an inert atmosphere. By comparing the numerical behavior of polycyclic aromatic hydrocarbons (PAHs) formation and nucleation with experimental configurations of carbon black, the impacts of the behavior of PAHs formation and nucleation on the configurations are discussed. The development rate of the particle size distribution increases with an increase in temperature, and the size of small particles (size below 10 nm) decreases with an increase in residence time. The sensitivity of the furnace temperature on the particle size distribution and morphology of carbon black were further investigated by performing the calculation with the temperature being constant. Although the nucleation rate is nearly identical between 1,850 and 2,000 K, the rate decreases below 1,750 K. The mole fraction decreases with an increase in temperature, especially at 2,000 K, although the differences are small below 1,850 K. To form the complex aggregate shapes, three requirements should be fulfilled: (i) large particle number concentration, (ii) high nucleation rate, and (iii) quench before small particles of size below 10 nm collide with large particles consisting of a log-normal distribution. With these requirements fulfilled, the aggregate shapes would become the most complex at 1,850 K with a residence time of around 40 ms for the current benzene pyrolysis.

Detailed kinetic analysis of the effect of benzene–acetylene composition on the configuration of carbon nanoparticles

Abstract The reasons why benzene–acetylene composition has an effect on the configuration of carbon black, which is a type of carbon nanoparticle, were investigated using a fixed sectional approach by applying the detailed chemical kinetic reaction for our previous experimental work: the pyrolysis of benzene–acetylene in an inert atmosphere. By comparing the calculated behavior of polycyclic aromatic hydrocarbon formation, nucleation, and the particle size distribution with experimentally observed configurations for carbon black, the impact of the benzene–acetylene composition on the configuration of carbon black is discussed. The nuclei mole fraction increases with additive concentration, which strongly affects the complexity of the aggregate shape. Specifically, when the amount of benzene added to 3.0 vol% acetylene is increased to 5.0 vol% benzene, the particle number concentration of 30–80-nm-sized particles, which are considered as primary particles or spherical aggregates, increases. The increase in the number concentration of 30–80-nm-sized particles contributes to the simplification of the aggregate shapes. When acetylene is added to 1.0 vol% benzene, although the particle size distribution at 200 ms begins to shift to a bimodal shape with the addition of 0.5 vol% acetylene, a log-normal shape clearly appears at 200 ms with the addition of 5.0 vol% acetylene because the nuclei mole fraction reaches equilibrium at 200 ms. Thus, if the reaction is quenched before small particles (

Evaluation of the enantioselectivity of carbon nanoparticles‐modified chiral separation systems using dextrin as chiral selector by capillary electrokinetic chromatography

Nanoparticles (NPs) can be used as pseudostationary phases (PSPs) in EKC, which is similar to the use of micelle additives as applied in MEKC. To date, the use of NPs to enhance enantiomeric separation by EKC with β-CD or its derivative as chiral selector has been reported only in two papers. However, to the best of our knowledge, there has been no prior effort to use NPs for achieving enantioseparation with polysaccharides as chiral selector. This paper describes for the first time the use of carbon nanoparticles (CNPs) as PSPs to modify chiral separation system employing dextrin as chiral selector for the enantioseparations of several basic drugs in capillary EKC. Three different types of CNPs, including carbogenic nanoparticles (NPs), carboxylated single-walled carbon nanotubes, and carboxylated multiwalled carbon nanotubes, were used as running buffer additives, respectively. The potential of the PSPs and the effects of dextrin concentration, buffer pH, and buffer concentration on the enantioseparations were evaluated. Four pairs of tested enantiomers were successfully resolved in less than 15 min with the resolution values in the range of 1.41-4.52 under optimized conditions. Compared to the buffer without NPs, the introduction of NPs into the buffer enhanced the separation of the enantiomers.

Microwave heating of arginine yields highly fluorescent nanoparticles

Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

In vivo evaluation of hydrogels of polyvinyl alcohol with and without carbon nanoparticles for osteochondral repair

Polyvinyl alcohol (PVA) hydrogels both pure and reinforced with two types of carbon nanoparticles (nanotubes and nanofibres) were studied as a candidate material for osteochondral defect repair. The carbon nanoparticles produced by chemical vapour deposition were characterised by Raman spectroscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The hydrogels were surgically implanted in osteochondral defects in the articular cartilage of rats and, after 3 and 12weeks of follow-up, examined by scanning electron microscopy (SEM), optical microscopy (OM), creep indentation test (CIT) and X-ray fluorescence (XRF). No sign of tissue adhesion or abrasive wear could be seen by SEM. OM revealed dense connective tissue at the interface after 3weeks and neoformed bone tissue without significant inflammatory process after 12weeks. Dense connective tissue could be seen at the pure-PVA/tissue interface after 12weeks, but not at the carbon reinforced-PVA/tissue interface after the same follow-up time. The hydrogel creep modulus increased with follow-up time. XRF revealed an increasing concentration of calcium and phosphorus in the implants over time, a phenomenon more pronounced for the hydrogels with carbon nanofibres. The results suggest that PVA hydrogel with carbon nanoparticles elicits a stronger biological response than pure hydrogel.

Positron Annihilation Spectroscopy of Polystyrene Filled with Carbon Nanomaterials

Positron annihilation lifetime spectroscopy (PALS) was employed to study the free volume properties of polystyrene (PS) containing three different types of carbon nanoparticles: polystyrene-grafted single wall carbon nanotubes (SWCNTs-g-PS), single wall carbon nanotubes (SWCNTs), and carbon nanofibers (CNFs). The glass transition temperature measured via PALS was significantly lower than that from differential scanning calorimetry (DSC), although qualitatively the two methods agreed in that the Tg measured increased as nanotubes were added to the material. There were some specific differences between the two measurements which may have been related to the fact that DSC does not measure Tg of a portion of the material which is immobilized on the surface of the particle, while PALS measures all polymer, whether immobilized or not. PALS was also used to measure the thermal expansion coefficient and distributions of the free volume of the polystyrene.

Polyvinyl alcohol associated with carbon nanotube scaffolds for osteogenic differentiation of rat bone mesenchymal stem cells

Polyvinyl alcohol (PVAl) hydrogel, alone and reinforced with two types of carbon nanoparticles, was studied in cultured cells to assess its potential use in treating osteochondral defects. The carbon nanoparticles were produced by hot-filament chemical vapour deposition. The carbon material was characterised with a Renishaw Invia Raman microscope system and the morphological particles were characterised with field emission scanning electron microscopy and high-resolution transmission electron microscopy. Cytotoxicity was evaluated by measuring the Vero fibroblast-type cells’ metabolic activity and studying their morphology. The osteogenic differentiation of mesenchymal stem cells obtained from rat bone marrow was evaluated by alkaline phosphatase (ALP) and alizarin red S (ARS) staining. Cell viability and morphology were assessed with thiazolyl blue tetrazolium bromide and scanning electron microscopy, respectively. The materials did not interfere with the viability, metabolic activity, morphology and spreading of either of the cell types analysed. Nodules of mineralised organic matrix were identified with ARS and ALP, confirming osteogenic differentiation. These results indicated higher concentration of ALP and mineralised matrix for PVAl with carbon nanoparticles. The results of this study indicate the potential use of carbon nanoparticles with PVAl hydrogels as orthopaedic biomaterials to treat osteochondral defects, but further in vivo investigations are still necessary.

Epoxy based photoresist/carbon nanoparticle composites

We have fabricated composites of SU-8 polymer and three different types of carbon nanoparticles (NPs) using ultrasonic mixing. Structures of composite thin films have been patterned on a characterization chip with standard UV photolithography. Using a four-point bending probe, a well defined stress is applied to the composite thin film and we have demonstrated that the composites are piezoresistive. Stable gauge factors of 5–9 have been measured, but we have also observed piezoresistive responses with gauge factors as high as 50. As SU-8 is much softer than silicon and the gauge factor of the composite material is relatively high, carbon nanoparticle doped SU-8 is a valid candidate for the piezoresistive readout in polymer based cantilever sensors, with potentially higher sensitivity than silicon based cantilevers.

A new approach to the toxicity testing of carbon-based nanomaterials—The clonogenic assay

The cellular toxicity of three types of carbon nanoparticles, namely HiPco ® single-walled carbon nanotubes (SWCNT), arc discharge SWCNT and Printex 90 carbon black nanoparticles, was studied on three different cell models including the human alveolar carcinoma epithelial cell line (A549), the normal human bronchial epithelial cell line (BEAS-2B) and the human keratinocyte cell line (HaCaT) using the clonogenic assay. Carbon nanomaterials are known to interact with colorimetric indicator dyes frequently used in cytotoxicity assays. By employing the clonogenic assay, any such interactions could be avoided, allowing a more reliable method for the in vitro toxicity assessment of carbon-based nanoparticles. It could be shown that the toxicity of as produced SWCNT samples differs between cell lines and the SWCNT production method used, with HiPco ® SWCNT samples being more reactive compared to arc discharge produced SWCNT samples, both eliciting a stronger cytotoxic response than carbon black. Furthermore, it was possible to distinguish between effects on cell viability and cell proliferation by including colony size as an additional endpoint in the clonogenic assay. All three particle types were highly effective in inhibiting cell proliferation in all three cell lines, whereas only HaCaT and BEAS-2B cells also showed decreased cell viability.

Thermal conductivity improvement in carbon nanoparticle doped PAO oil: An experimental study

The present work involves a study on the thermal conductivity of nanoparticle-oil suspensions for three types of nanoparticles, namely, carbon nanotubes (CNTs), exfoliated graphite (EXG), and heat treated nanofibers (HTT) with PAO oil as the base fluid. To accomplish the above task, an experimental analysis is performed using a modern light flash technique (LFA 447) for measuring the thermal conductivity of the three types of nanofluids, for different loading of nanoparticles. The experimental results show a similar trend as observed in literature for nanofluids with a maximum enhancement of approximately 161% obtained for the CNT-PAO oil suspension. The overall percent enhancements for different volume fractions of the nanoparticles are highest for the CNT-based nanofluid, followed by the EXG and the HTT. The findings from this study for the three different types of carbon nanoparticles can have great potential in the field of thermal management.

Tribological behavior of PTFE nanocomposite films reinforced with carbon nanoparticles

Carbon-based nanoparticles synthesized by heat treatment of nanodiamond in the temperature range of 1000–1900 °C were added to PTFE film to investigate the structural effect of the carbon particles on the tribological properties of PTFE composite film. Carbon-based nanoparticles were prepared by milling with micron sized beads in chemically treated water before their addition to PTFE film. The wear and frictional properties of PTFE nanocomposite film were measured by the ball on plate type wear test. The wear resistance of PTFE film was found to be enhanced by the addition of 2 wt% of carbon nanoparticles. The wear coefficient of PTFE film was decreased from 16.2 to 3.5 × 10 −6 mm 3/N m by the addition of carbon-based nanoparticles heat-treated at 1000 °C. Increasing the heating temperature of the nanodiamonds caused the extent of aggregation and particle size to increase. The wear resistance of PTFE nanocomposite film was enhanced by the addition of nanodiamonds heat-treated at 1000 °C, but decreased when the heat treatment temperature of carbon nanoparticles was further increased. Tribological behavior of PTFE nanocomposite films depending on the types of carbon nanoparticles were explained based on the structural, physical and chemical modification of carbon nanoparticles.

In Search of the Most Relevant Parameter for Quantifying Lung Inflammatory Response to Nanoparticle Exposure: Particle Number, Surface Area, or What?

BackgroundLittle is known about the mechanisms involved in lung inflammation caused by the inhalation or instillation of nanoparticles. Current research focuses on identifying the particle parameter that can serve as a proper dose metric.ObjectivesThe purpose of this study was to review published dose–response data on acute lung inflammation in rats and mice after instillation of titanium dioxide particles or six types of carbon nanoparticles. I explored four types of dose metrics: the number of particles, the joint length—that is, the product of particle number and mean size—and the surface area defined in two different ways.FindingsWith the exception of the particle size–based surface area, all other parameters worked quite well as dose metrics, with the particle number tending to work best. The apparent mystery of three equally useful dose metrics could be explained. Linear dose–response relationships were identified at sufficiently low doses, with no evidence of a dose threshold below which nanoparticle instillation ceased to cause inflammation. In appropriately reduced form, the results for three different sets of response parameters agreed quite well, indicating internal consistency of the data. The reduced data revealed particle-specific differences in surface toxicity of the carbon nanoparticles, by up to a factor of four, with diesel soot being at the low end.ConclusionsThe analysis suggests that the physical characterization of nanoparticles and the methods to determine surface toxicity have to be improved significantly before the appropriate dose metric for lung inflammation can be identified safely. There is also a need for refinements in quantifying response to exposure.