Cytotoxicity Effects of Graphene and Single-Wall Carbon Nanotubes in Neural Phaeochromocytoma-Derived PC12 Cells

Neurochemistry Laboratory, Division of Neurotoxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, Jefferson, Arkansas 72079, USA.
ACS Nano (Impact Factor: 12.88). 06/2010; 4(6):3181-6. DOI: 10.1021/nn1007176
Source: PubMed


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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    • "Some researchers believe that low doses of graphene and GO may be environmentally safe. For example, Zhang et al. (2010) found that concentrations of graphene as low as 0.01 mg/mL, had no effect on metabolic activity, lactate dehydrogenase (LDH) release, and generation of ROS. Wang et al. (2013) found that concentrations of GO less than 20 mg/mL had little toxicity on human lung fibroblast cells. "
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    ABSTRACT: Low levels of graphene and graphene oxide (GO) are considered to be environmentally safe. In this study, we analyzed the potential effects of graphene and GO at relatively low concentrations on cellular xenobiotic defense system mediated by efflux transporters. The results showed that graphene (<0.5 μg/mL) and GO (<20 μg/mL) did not decrease cell viability, generate reactive oxygen species, or disrupt mitochondrial function. However, graphene and GO at the nontoxic concentrations could increase calcein-AM (CAM, an indicator of membrane ATP-binding cassette (ABC) transporter) activity) accumulation, indicating inhibition of ABC transporters' efflux capabilities. This inhibition was observed even at 0.005 μg/mL graphene and 0.05 μg/mL GO, which are 100 times and 400 times lower than their lowest toxic concentration from cytotoxicity experiments, respectively. The inhibition of ABC transporters significantly increased the toxicity of paraquat and arsenic, known substrates of ABC transporters. The inhibition of ABC transporters was found to be based on graphene and GO damaging the plasma membrane structure and fluidity, thus altering functions of transmembrane ABC transporters. This study demonstrates that low levels of graphene and GO are not environmentally safe since they can significantly make cell more susceptible to other xenobiotics, and this chemosensitizing activity should be considered in the risk assessment of graphene and GO.
    No preview · Article · Nov 2015 · Nanotoxicology
    • "A number of studies performed with CNTs have evaluated their toxicity to different organs, such as the lungs, kidneys, and liver (Awasthi et al., 2013; Deng et al., 2009; Li et al., 2007). Several in vitro studies have confirmed that CNTs could generate neurotoxic effects, including decreasing cell activity (Belyanskaya et al., 2009; Zhang et al., 2010). In addition, our previous studies have showed that MWCNTs induce cytotoxicity in C6 cells (Han et al., 2012) and inhibit CA1 glutamatergic synaptic transmission in rat hippocampal slices in vitro (Chen et al., 2014). "
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    ABSTRACT: Multi-walled carbon nanotubes (MWCNTs) have shown potential applications in many fields, especially in the field of biomedicine. Several studies have reported that MWCNTs induce apoptosis and oxidative damage in nerve cells during in vitro experiments. However, there are few studies focused on the neurotoxicity of MWCNTs used in vivo. Many studies have reported that autophagy, a cellular stress response to degrade damaged cell components, can be activated by diverse nanoparticles. In this study, we investigated the neurotoxic effects of MWCNTs on hippocampal synaptic plasticity and spatial cognition in rats. Then, we used an inhibitor of autophagy called chloroquine (CQ) to examine whether autophagy plays an important role in hippocampal synaptic plasticity, since this was damaged by MWCNTs. In this study, adult male Wister rats were randomly divided into three groups: a control group, a group treated with MWCNTs (2.5mg/kg/day) and a group treated with MWCNTs+CQ (20mg/kg/day). After two-weeks of intraperitoneal (i.p.) injections, rats were subjected to the Morris water maze (MWM) test, and the long-term potentiation (LTP) and other biochemical parameters were determined. Results showed that MWCNTs could induce cognitive deficits, histopathological alteration and changes of autophagy level (increased the ratio of LC3 II /LC3 I and the expression of Beclin-1). Furthermore, we found that CQ could suppress MWCNTs-induced autophagic flux and partly rescue the synapse deficits, which occurred with the down-regulation of NR2B (a subunit of NMDA receptor) and synaptophysin (SYP) in the hippocampus. Our results suggest that MWCNTs could induce cognitive deficits in vivo via the increased autophagic levels, and provide a potential strategy to avoid the adverse effects of MWCNTs. Copyright © 2015. Published by Elsevier Ireland Ltd.
    No preview · Article · Aug 2015 · Toxicology
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    • "Concerning the cytotoxic effects of graphene on cells, dose-dependent cytotoxicity of graphene in human erythrocytes and skin fibroblasts was studied by Liao et al. [21]. In addition, dose-and timedependent cytotoxicity of graphene and graphene oxide (GO) on neural pheochromocytoma-derived PC12 [22], A549 [23], and human mesenchymal stem cells (hMSCs) [24] were investigated and the main mechanism of cytotoxicity was assigned to the generation of reactive oxygen species (ROS). The cell membrane damage induced by physically interaction of the cells with the extremely sharp edges of GO [25] [26], change in the chemical state of GO sheets into reduced graphene oxide (rGO) ones under metabolic activity of microorganisms [27] and entrapping microorganisms by aggregating the rGO sheets in a suspension [28] have also been proposed as other mechanisms of cytotoxicity. "
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    ABSTRACT: In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and chromosomal aberrations of the spermatozoa after ∼8 weeks from the first weekly injection were assigned to the involvement of the NGO in spermatogenesis of the mice. The uptake of the NGO in the testis could also increase the generation of reactive oxygen species in semen of the mice. Moreover, semen of the NGO-treated mice (containing the damaged spermatozoa) might disturb the hormone secretion and pregnant functionality of female mice (∼44, 35 and 59% reduction in fertility, gestation ability and multi-production capability) and also viability of the next generation (∼15% reduction in postnatal viability of delivered pups).
    Full-text · Article · Aug 2015 · Carbon
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