Cytotoxicity Effects of Graphene and Single-Wall Carbon Nanotubes in Neural Phaeochromocytoma-Derived PC12 Cells
ABSTRACT Graphitic nanomaterials such as graphene layers (G) and single-wall carbon nanotubes (SWCNT) are potential candidates in a large number of biomedical applications. However, little is known about the effects of these nanomaterials on biological systems. Here we show that the shape of these materials is directly related to their induced cellular toxicity. Both G and SWCNT induce cytotoxic effects, and these effects are concentration- and shape-dependent. Interestingly, at low concentrations, G induced stronger metabolic activity than SWCNT, a trend that reversed at higher concentrations. Lactate dehydrogenase levels were found to be significantly higher for SWCNT as compared to the G samples. Moreover, reactive oxygen species were generated in a concentration- and time-dependent manner after exposure to G, indicating an oxidative stress mechanism. Furthermore, time-dependent caspase 3 activation after exposure to G (10 microg/mL) shows evidence of apoptosis. Altogether these studies suggest different biological activities of the graphitic nanomaterials, with the shape playing a primary role.
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- "In parallel to efforts directed at identifying new applications for carbon nanotubes (CNTs) and at improving ways to mass-produce them  , efforts are underway to examine health and ecological effects of these materials, as increasing production and use certainly will lead to release to the environment and biological exposure   . Of the several proposed processes used to explain toxicity of these materials, ''oxidative stress'' is recognized as one of the likely causes     . Oxidative stress presumably occurs through reactive oxygen species (ROS) generation, and while mechanisms of photo-induced ROS generation by CNTs has been reported   , there is limited information on light-independent generation of ROS and the underlying mechanisms responsible for this generation . "
ABSTRACT: Although induction of oxidative stress is widely accepted as one of the major cytotoxic effects of carbon nanotubes (CNTs), there is no solid understanding of how biological redox reactions are affected and how reactive oxygen species (ROS) are generated by CNTs, especially when they are coated with various dispersing agents. In this study, we investigated electron transfer from biological reducing agents through nonfunctionalized single-walled carbon nanotubes (SWCNTs) to molecular oxygen, generating ROS in the process. Electron transfer rates in the colloidal SWCNT suspensions depended on the dispersant used to stabilize them, with six dispersants examined. Oxidation of both nicotinamide adenine dinucleotide (NADH) and dithiothreitol was catalyzed by SWCNTs coated with either cetyltrimethylammonium bromide (CTAB) or Suwannee River natural organic matter (SRNOM). SWCNTs coated with other types of surfactants showed only slight effect. In the presence of NADH or dithiothreitol, generation of ROS also was dispersant-dependent, with CTAB- and SRNOM-coated SWCNTs generating significant amounts of superoxide anion and hydrogen peroxide. In systems containing xanthine and xanthine oxidase, accumulated charge on the SWCNTs appeared to be transferred to superoxide anion, resulting in indirect disproportionation of superoxide anion, forming more hydrogen peroxide.Carbon 08/2015; 89:361-371. DOI:10.1016/j.carbon.2015.03.052 · 6.16 Impact Factor
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- "However, in this type of toxicity, the key role is played by factors such as the duration of the culture and the graphene structure defined as the number of layers, shape, texture and its dimensions.   It has been found that the most crucial factors that play an important role in the cell culture are the changes in the hydrophilic/hydrophobic nature of the substrate and its roughness.[7,9À11] With regard to the cytotoxic effects, what is of particular importance is the purity of the substrate, which is fundamentally different in products obtained from carbon *Corresponding author. "
ABSTRACT: In tissue engineering, the possibility of a comprehensive restoration of the tissue, structure or a portion of the organ is largely determined by the type of material used. A wide range of materials such as graphene and other carbon nanocompounds which have different physical and chemical properties can be expected to react differently upon contact with biomolecules, cells and tissues. This mini-review describes the current knowledge on biocompatibility of graphene and its derivatives with a variety of mammalian cells, such as osteoblasts, neuroendocrine cells, fibroblasts NIH/3T3 line, PMEFs (primary mouse embryonic fibroblasts), stem cells and neurons. The results from different studies give hope for the possibility of graphene to be used in the regeneration of almost all tissues, including neural tissue implants or in the form of neural chips, which may allow in the future treatment of degenerative diseases and injuries of the central nervous system.Biotechnology & Biotechnological Equipment 02/2015; 29(3). DOI:10.1080/13102818.2015.1009726 · 0.38 Impact Factor
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- "Graphene is a monolayer carbon nano particle that consists of sp 2 hybridized carbon atoms arranged in hexagonal planar structures. Properties that have endeared this unique material to diverse applications are its exceptional mechanical strength (Young's modulus of 1 TPa, tensile strength of 20 GPa)  , excellent electrical (5000 S/m)  thermal conductivities and stability (~3000 W/m K) . Therefore , it is logical to expect that incorporating graphene into polymeric matrices will improve the flammability and thermal conductivity of the host polymers significantly. "
ABSTRACT: Nanocomposites based polyethylene terephthalate (PET)/polypropylene (PP) (70/30 wt%) blends and exfoliated graphite nanoplatelets (GNP) as reinforcing fillers were developed using melt extrusion process. The filler concentration was varied between 0 -5.98 wt percent (%) (0–7 phr). The resulting nanocomposites were characterized in terms of flame retardancy, thermal conductivity, thermal behavior, morphology and structure. Cone calorimeter analysis, limiting oxygen index (LOI) and UL94 flame rating tests revealed that addition of GNPs to PET/PP improved the flame retardancy of PET/PP/GNP nanocomposites significantly. Cone calorimeter data show a significant reduction of peak heat release rate (PHRR), mass loss rate and delayed time to ignition (TTI) due to addition of GNPs to PET/PP blend. As much as 37% reduction in PHRR and 32% increase in TTI were observed for the maximum GNP loading. Enhancements of flammability properties were attributed to the development of compact, dense, uniform char layers on the surface of nanocomposites. The effective thermal conductivity was found to vary linearly with GNP loading which was attributed to the formation of effective interconnected heat conduction bridges formed by the GNPs. It was found that the effective thermal conductivity of the nanocomposites was increased by about 80%, i.e. from 1.2 W/m.K for the unreinforced PET/PP blend to 1.9 W/m K for the 5.98 wt% (7 phr) reinforced PET/PP/GNP nanocomposites. Differential scanning calorimetry results indicated that the addition of GNPs increased crystallization temperatures but decreased degree of crystallinity of PET/PP/GNP nanocomposites. However; the melting points remained essentially unaffected. Transmission electron microscopy and field emission scanning electron microscopy showed uniform dispersion of GNPs in the matrix with the formation of interconnected GNP sheets at 3 phr. Isolated instances of exfoliation of GNPs was also observed.Polymer Degradation and Stability 12/2014; 110:137–148. DOI:10.1016/j.polymdegradstab.2014.08.025 · 2.63 Impact Factor