A systems toxicology approach to the surface functionality control of graphene-cell interactions

Benefits in the Macrophage Response Due to Graphene Oxide Reduction by Thermal Treatment

Graphene and its derivatives are very promising nanomaterials for biomedical applications and are proving to be very useful for the preparation of scaffolds for tissue repair. The response of immune cells to these graphene-based materials (GBM) appears to be critical in promoting regeneration, thus, the study of this response is essential before they are used to prepare any type of scaffold. Another relevant factor is the variability of the GBM surface chemistry, namely the type and quantity of oxygen functional groups, which may have an important effect on cell behavior. The response of RAW-264.7 macrophages to graphene oxide (GO) and two types of reduced GO, rGO15 and rGO30, obtained after vacuum-assisted thermal treatment of 15 and 30 min, respectively, was evaluated by analyzing the uptake of these nanostructures, the intracellular content of reactive oxygen species, and specific markers of the proinflammatory M1 phenotype, such as CD80 expression and secretion of inflammatory cytokines TNF-α and IL-6. Our results demonstrate that GO reduction resulted in a decrease of both oxidative stress and proinflammatory cytokine secretion, significantly improving its biocompatibility and potential for the preparation of 3D scaffolds able of triggering the appropriate immune response for tissue regeneration.

Graphene Family Nanomaterials in Ocular Applications: Physicochemical Properties and Toxicity

Graphene family nanomaterials (GFNs) are rapidly emerging for ocular applications due to their outstanding physicochemical properties. Since the eyes are very sensitive organs and the contact between the eyes and GFNs in eye drops, contact lenses, intraocular drug delivery systems and biosensors and even the workers handling these nanomaterials is inevitable, it is necessary to investigate their ocular toxicities and physiological interactions with cells as well as their toxicity mechanisms. The toxicity of GFNs can be extremely affected by their physicochemical properties, including composition, size, surface chemistry, and oxidation level as well as dose and the time of exposure. Up to now, there are several studies on the in vitro and in vivo toxicity of GFNs; however, a comprehensive review on ocular toxicity and applications of GFNs is missing, and a knowledge about the health risks of eye exposure to the GFNs is predominantly unspecified. This review highlights the ocular applications of GFNs and systematically covers the most recent advances of GFNs' physicochemical properties, in vitro and in vivo ocular toxicity, and the possible toxicity mechanisms as well as provides some perspectives on the potential risks of GFNs in material development and biomedical applications.

Factors affecting the biological response of Graphene

Nanotechnology has gained significant importance in different fields of medical, electronic, and environmental science. This technology is founded on the use of materials at the nanoscale scale (1-100 nanometers) for various purposes, particularly in the biomedical area, where its application is growing daily due to the need of materials with advanced properties. Over the past few years, there has been a growing use for graphene and its derivative composite materials. However, different physico-chemical properties influence its biological response; therefore, further studies to explain the interactions of these nanomaterials with biological systems are critical. This review presents the current advances in the applications of graphene in biomedicine with a focus on the physico-chemical characteristics of the graphene family and their influences on biological interactions.

Graphitic Carbon Nitride Causes Widespread Global Molecular Changes in Epithelial and Fibroblast Cells

For scaffold and imaging applications, nanomaterials such as graphene and its derivatives have been widely used. Graphitic carbon nitride (g-C₃N₄) is among one such derivative of graphenes, which draws strong consideration due to its physicochemical properties and photocatalytic activity. To use g-C₃N₄ for biological applications, such as molecular imaging or drug delivery, it must interact with the epithelium, cross the epithelial barrier, and then come in contact with the extracellular matrix of the fibroblast cells. Thus, it becomes essential to understand its molecular mechanism of action. Hence, in this study, to understand the molecular reprogramming associated with g-C₃N₄, global gene expression using DNA microarrays and proteomics using tandem mass tag (TMT) labeling and mass spectrometry were performed in epithelial and fibroblast cells, respectively. Our results showed that g-C₃N₄ can cross the epithelial barrier by regulating the adherens junction proteins. Further, using g-C₃N₄-PDMS scaffolds as a mimic of the extracellular matrix for fibroblast cells, the common signaling pathways were identified between the epithelium and fibroblast cells. These pathways include Wnt signaling, integrin signaling, TGF-β signaling, cadherin signaling, oxidative stress response, ubiquitin proteasome pathway, and EGF receptor signaling pathways. These altered signature pathways identified could play a prominent role in g-C₃N₄-mediated cellular interactions in both epithelial and fibroblast cells. Additionally, β catenin, EGFR, and MAP2K2 protein-protein interaction networks could play a prominent role in fibroblast cell proliferation. The findings could further our knowledge on g-C₃N₄-mediated alterations in cellular molecular signatures, enabling the potential use of these materials for biological applications such as molecular imaging and drug delivery.

Lateral size of graphene oxide determines differential cellular uptake and cell death pathways in Kupffer cells, LSECs, and hepatocytes

As a representative two-dimensional (2D) nanomaterial, graphene oxide (GO) has shown high potential in many applications due to its large surface area, high flexibility, and excellent dispersibility in aqueous solutions. These properties make GO an ideal candidate for bio-imaging, drug delivery, and cancer therapy. When delivered to the body, GO has been shown to accumulate in the liver, the primary accumulation site of systemic delivery or secondary spread from other uptake sites, and induce liver toxicity. However, the contribution of the GO physicochemical properties and individual liver cell types to this toxicity is unclear due to property variations and diverse cell types in the liver. Herein, we compare the effects of GOs with small (GO-S) and large (GO-L) lateral sizes in three major cell types in liver, Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), and hepatocytes. While GOs induced cytotoxicity in KCs, they induced significantly less toxicity in LSECs and hepatocytes. For KCs, we found that GOs were phagocytosed that triggered NADPH oxidase mediated plasma membrane lipid peroxidation, which leads to PLC activation, calcium flux, mitochondrial ROS generation, and NLRP3 inflammasome activation. The subsequent caspase-1 activation induced IL-1β production and GSDMD-mediated pyroptosis. These effects were lateral size-dependent with GO-L showing stronger effects than GO-S. Amongst the liver cell types, decreased cell association and the absence of lipid peroxidation resulted in low cytotoxicity in LSECs and hepatocytes. Using additional GO samples with different lateral sizes, surface functionalities, or thickness, we further confirmed the differential cytotoxic effects in liver cells and the major role of GO lateral size in KUP5 pyroptosis by correlation studies. These findings delineated the GO effects on cellular uptake and cell death pathways in liver cells, and provide valuable information to further evaluate GO effects on the liver for biomedical applications.

Graphene Oxide and Reduced Graphene Oxide Exhibit Cardiotoxicity Through the Regulation of Lipid Peroxidation, Oxidative Stress, and Mitochondrial Dysfunction

Objective

Graphene has been widely used for various biological and biomedical applications due to its unique physiochemical properties. This study aimed to evaluate the cardiotoxicity of graphene oxide (GO) and reduced GO (rGO) in vitro and in vivo, as well as to investigate the underlying toxicity mechanisms.

Methods

GO was reduced by gamma irradiation to prepare rGO and then characterized by UV/visible light absorption spectroscopy. Rat myocardial cells (H9C2) were exposed to GO or rGO with different absorbed radiation doses. The in vitro cytotoxicity was evaluated by MTT assay, cell apoptosis assay, and lactate dehydrogenase (LDH) activity assay. The effects of GO and rGO on oxidative damage and mitochondrial membrane potential were also explored in H9C2 cells. For in vivo experiments, mice were injected with GO or rGO. The histopathological changes of heart tissues, as well as myocardial enzyme activity and lipid peroxidation indicators in heart tissues were further investigated.

Results

rGO was developed from GO following different doses of gamma irradiation. In vitro experiments in H9C2 cells showed that compared with control cells, both GO and rGO treatment inhibited cell viability, promoted cell apoptosis, and elevated the LDH release. With the increasing radiation absorbed dose, the cytotoxicity of rGO gradually increased. Notably, GO or rGO treatment increased the content of ROS and reduced the mitochondrial membrane potential in H9C2 cells. In vivo experiments also revealed that GO or rGO treatment damaged the myocardial tissues and changed the activities of several myocardial enzymes and the lipid peroxidation indicators in the myocardial tissues.

Conclusion

GO exhibited a lower cardiotoxicity than rGO due to the structure difference, and the cardiotoxicity of GO and rGO might be mediated by lipid peroxidation, oxidative stress, and mitochondrial dysfunction.

Graphene oxide induces dose-dependent lung injury in rats by regulating autophagy

Graphene is a two-dimensional structured material with a hexagonal honeycomb lattice composed of carbon atoms. The biological effects of graphene oxide (GO) have been extensively investigated, as it has been widely used in biological research due to its increased hydrophilicity/biocompatibility. However, the exact mechanisms underlying GO-associated lung toxicity have not yet been fully elucidated. The aim of the present study was to determine the role of GO in lung injury induction, as well as its involvement in oxidative stress, inflammation and autophagy. The results revealed that lower concentrations of GO (5 and 10 mg/kg) did not cause significant lung injury, but the administration of GO at higher concentrations (50 and 100 mg/kg) induced lung edema, and increased lung permeability and histopathological lung changes. High GO concentrations also induced oxidative injury and inflammatory reactions in the lung, demonstrated by increased levels of oxidative products [malondialdehyde(MDA) and 8-hydroxydeoxyguanosine (8-OHdG)] and inflammatory factors (TNF-α, IL-6, IL-1β and IL-8). The autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CLQ) inhibited autophagy in the lung and attenuated GO-induced lung injury, as demonstrated by a reduced lung wet-to-dry weight ratio, lower levels of protein in the bronchoalveolar lavage fluid, and a reduced lung injury score. Furthermore, 3-MA and CLQ significantly reduced the levels of MDA, 8-OHdG and inflammatory factors in lung tissue, suggesting that autophagy also mediates the development of oxidative injury and inflammation in the lung. Finally, autophagy was directly inhibited in BEAS-2B cells by short hairpin RNA-mediated autophagy protein 5 (ATG5) knockdown, which were then treated with GO. Cell viability, as well as the extent of injury (indicated by lactate dehydrogenase level) and oxidative stress were determined. The results revealed that ATG5 knockdown-induced autophagic inhibition significantly decreased cellular injury and oxidative stress, suggesting that autophagy induction is a key event that leads to lung injury during exposure to GO. In conclusion, the findings of the present study indicated that GO causes lung injury in a dose-dependent manner by inducing autophagy.

Graphene-Based Scaffolds for Regenerative Medicine

Leading-edge regenerative medicine can take advantage of improved knowledge of key roles played, both in stem cell fate determination and in cell growth/differentiation, by mechano-transduction and other physicochemical stimuli from the tissue environment. This prompted advanced nanomaterials research to provide tissue engineers with next-generation scaffolds consisting of smart nanocomposites and/or hydrogels with nanofillers, where balanced combinations of specific matrices and nanomaterials can mediate and finely tune such stimuli and cues. In this review, we focus on graphene-based nanomaterials as, in addition to modulating nanotopography, elastic modulus and viscoelastic features of the scaffold, they can also regulate its conductivity. This feature is crucial to the determination and differentiation of some cell lineages and is of special interest to neural regenerative medicine. Hereafter we depict relevant properties of such nanofillers, illustrate how problems related to their eventual cytotoxicity are solved via enhanced synthesis, purification and derivatization protocols, and finally provide examples of successful applications in regenerative medicine on a number of tissues.

Toxicity of Graphene: An Update

Graphene possesses wider biomedical applications including drug delivery, photothermal ablation of tumors, biosensors, and also in the disease diagnosis. The accidental or intentional exposure of the environment including plants, ecosystem, and humans toward graphene is gradually increasing. Therefore, graphene toxicity becomes a critical issue to be addressed despite their diverse applications in multiple fields. In this situation, the scientific community as well as the general public must get awareness about the toxicity of graphene. This article, therefore, reviews the investigations on graphene toxicity. This review reveals the toxicity of graphene in vitro, in vivo models along with the environmental toxicity. The advantages of graphene toxicity in bacterial cells and cancer cells were also reviewed.

Engineering the surface of graphene oxide with bovine serum albumin for improved biocompatibility in Caenorhabditis elegans

Graphene oxide (GO) has been extensively studied for its potential biomedical applications. However, its potential risk associated with the interactions of GO in a biological system hampers its biomedical applications. Therefore, there is an urgent need to enhance the biocompatibility of GO. In the present study, we decorated the surface of GO with bovine serum albumin (GO-BSA) to mitigate the in vivo toxic properties of GO. An in vivo model Caenorhabditis elegans has been used to study the potential protective effect of BSA decoration in mitigating GO induced toxicity. The BSA decoration on the surface of GO prevents the acute and prolonged toxicity induced by GO in primary and secondary organs by maintaining normal intestinal permeability, defecation behavior, development, and reproduction. Notably, GO-BSA treatment at 0.5-100 mg L^-1 does not affect the intracellular redox status and lifespan of C. elegans. Reporter gene expression analysis revealed that exposure to GO-BSA (100 mg L^-1) did not significantly influence the nuclear accumulation and expression patterns of DAF-16/FOXO and SKN-1/Nrf2 transcription factors and their downstream target genes sod-3, hsp-16.2, ctl-1,2,3, gcs-1, and gst-4 when compared to exposure to pristine GO. Also, quantitative real-time PCR results showed that GO-BSA did not alter the expression of genes involved in regulating DNA damage checkpoints (cep-1, hus-1 and egl-1) and core signaling pathways of apoptosis (ced-4, ced-3 and ced-9), in contrast to GO treatment. All these findings will have an impact on the future development of safer nanomaterial formulations of graphene and graphene-based materials for environmental and biomedical applications.

Comprehensive Biological Evaluation of Biomaterials Used in Spinal and Orthopedic Surgery

Biological acceptance is one of the most important aspects of a biomaterial and forms the basis for its clinical use. The aim of this study was a comprehensive biological evaluation (cytotoxicity test, bacterial colonization test, blood platelets adhesion test and transcriptome and proteome analysis of Saos-2 cells after contact with surface of the biomaterial) of biomaterials used in spinal and orthopedic surgery, namely, Ti6Al4V ELI (Extra Low Interstitials), its modified version obtained as a result of melting by electron beam technology (Ti6Al4V ELI-EBT), polyether ether ketone (PEEK) and polished medical steel American Iron and Steel Institute (AISI) 316L (the reference material). Biological tests were carried out using the osteoblasts-like cells (Saos-2, ATCC HTB-85) and bacteria Escherichia coli (DH5α). Results showed lack of cytotoxicity of all materials and the surfaces of both Ti6Al4V ELI and PEEK exhibit a significantly higher resistance to colonization with E. coli cells, while the more porous surface of the same titanium alloy produced by electron beam technology (EBT) is more susceptible to microbial colonization than the control surface of polished medical steel. None of the tested materials showed high toxicity in relation to E. coli cells. Susceptibility to platelet adhesion was very high for polished medical steel AISI 316L, whilst much lower for the other biomaterials and can be ranked from the lowest to the highest as follows: PEEK < Ti6Al4V ELI < Ti6Al4V ELI-EBT. The number of expressed genes in Saos-2 cells exposed to contact with the examined biomaterials reached 9463 genes in total (ranging from 8455 genes expressed in cells exposed to ELI to 9160 genes in cells exposed to PEEK). Whereas the number of differentially expressed proteins detected on two-dimensional electrophoresis gels in Saos-2 cells after contact with the examined biomaterials was 141 for PEEK, 223 for Ti6Al4V ELI and 133 for Ti6Al4V ELI-EBT. Finally, 14 proteins with altered expression were identified by mass spectrometry. In conclusion, none of the tested biomaterials showed unsatisfactory levels of cytotoxicity. The gene and protein expression analysis, that represents a completely new approach towards characterization of these biomaterials, showed that the polymer PEEK causes much more intense changes in gene and protein expression and thus influences cell metabolism.

A Comprehensive Insight Towards Pharmaceutical Aspects of Graphene Nanosheets

Graphene Derivatives (GDs) have captured the interest and imagination of pharmaceutical scientists. This review exclusively provides pharmacokinetics and pharmacodynamics information with a particular focus on biopharmaceuticals. GDs can be used as multipurpose pharmaceutical delivery systems due to their ultra-high surface area, flexibility, and fast mobility of charge carriers. Improved effects, targeted delivery to tissues, controlled release profiles, visualization of biodistribution and clearance, and overcoming drug resistance are examples of the benefits of GDs. This review focuses on the application of GDs for the delivery of biopharmaceuticals. Also, the pharmacokinetic properties and the advantage of using GDs in pharmaceutics will be reviewed to achieve a comprehensive understanding about the GDs in pharmaceutical sciences.

Toxic impacts and industrial potential of graphene

Advancement in the field of nanotechnology has increased the synthesis and exploitation of graphene-like nanomaterials. Graphene is a two-dimensional planar and hexagonal array of carbon atoms. Due to its flexible nature graphene and its derivatives have several significant prospects extending from electronics to life sciences and drug delivery systems. In this review, we enlist some of the toxic effects of graphene family nanomaterials (GFNs) in various aspects of biosystems viz., in vitro, in vivo, microbial, molecular and environmental. We also appreciate their extensive and promising applications though with some underlying challenges. This review also draws attention toward current and future prospect of global graphene market for wide-range commercialization.

Theranostic Nanoplatforms of Thiolated Reduced Graphene Oxide Nanosheets and Gold Nanoparticles

In this study, graphene oxide (GO) and reduced-thiolated GO (rGOSH) were used as 2D substrate to fabricate nanocomposites with nanoparticles of gold nanospheres (AuNS) or nanorods (AuNR), via in situ reduction of the metal salt precursor and seed-mediated growth processes. The plasmonic sensing capability of the gold-decorated nanosheets were scrutinized by UV-visible (UV-VIS) spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), and atomic force microscopy (AFM) were performed in order to prove the actual reduction that occurred concomitantly with the thiolation of GO, the increase in the hydrophobic character as well as the size, and preferential gathering of the gold nanoparticles onto the nanosheet substrates, respectively. Moreover, the theoretical electronic and infrared absorption (UV-VIS and IR) spectra were calculated within a time-dependent approach of density functional theory (DFT). Eventually, in vitro cellular experiments on human neuroblastoma cells (SH-SY5Y line) were carried out in order to evaluate the nanotoxicity of the nanocomposites by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium reduction (MTT) colorimetric assay. Results pointed out the promising potential of these hybrids as plasmonic theranostic platforms with different hydrophilic or hydrophobic features as well as cytotoxic effects against cancer cells.

2D materials in electrochemical sensors for in vitro or in vivo use

Individual cells and cell populations are at the present time investigated with a myriad of analytical tools. While most of them are commercially available, some of these analytical tools are just emerging from research laboratories and are in the developmental phase. Electrochemical sensors which allow the monitoring of low molecular weight compounds released (and / or uptaken) by cells are among these emerging tools. Such sensors are increasingly built using 2D materials (e.g. graphene-based materials, transition metal dichalcogenides, etc.) with the aim of conferring better analytical performances to these devices. The present work critically reviews studies published during the last 10 years describing electrochemical sensors made with 2D materials and exploited to monitor small compounds (e.g. H₂O₂, ·NO, glucose, etc.) in living biological systems. It also discusses the very few 2D material-based electrochemical sensors which are wearable or usable in vivo. Finally, the present work includes a specific section about 2D material biocompatibility, a fundamental requirement for 2D material-based sensor applications in vitro and in vivo. As such, the review provides a critical view on the state of the art of electrochemical sensors made with 2D materials and used at cellular level and it evaluates the possibility that such sensors will be used on / in the human body on a wider scale.

Anti-Angiogenic and Anti-Proliferative Graphene Oxide Nanosheets for Tumor Cell Therapy

Graphene oxide (GO) is a bidimensional novel material that exhibits high biocompatibility and angiogenic properties, mostly related to the intracellular formation of reactive oxygen species (ROS). In this work, we set up an experimental methodology for the fabrication of GO@peptide hybrids by the immobilization, via irreversible physical adsorption, of the Ac-(GHHPH)₄-NH₂ peptide sequence, known to mimic the anti-angiogenic domain of the histidine-proline-rich glycoprotein (HPRG). The anti-proliferative capability of the graphene-peptide hybrids were tested in vitro by viability assays on prostate cancer cells (PC-3 line), human neuroblastoma (SH-SY5Y), and human retinal endothelial cells (primary HREC). The anti-angiogenic response of the two cellular models of angiogenesis, namely endothelial and prostate cancer cells, was scrutinized by prostaglandin E2 (PGE₂) release and wound scratch assays, to correlate the activation of inflammatory response upon the cell treatments with the GO@peptide nanocomposites to the cell migration processes. Results showed that the GO@peptide nanoassemblies not only effectively induced toxicity in the prostate cancer cells, but also strongly blocked the cell migration and inhibited the prostaglandin-mediated inflammatory process both in PC-3 and in HRECs. Moreover, the cytotoxic mechanism and the internalization efficiency of the theranostic nanoplatforms, investigated by mitochondrial ROS production analyses and confocal microscopy imaging, unraveled a dose-dependent manifold mechanism of action performed by the hybrid nanoassemblies against the PC-3 cells, with the detection of the GO-characteristic cell wrapping and mitochondrial perturbation. The obtained results pointed out to the very promising potential of the synthetized graphene-based hybrids for cancer therapy.

Differential histological, cellular and organism-wide response of earthworms exposed to multi-layer graphenes with different morphologies and hydrophobicity

The growing use of graphene-based nanomaterials (GBNs) for various applications increases the probability of their environmental releases and calls for a systematic assessment of their potential impacts on soil invertebrates that serve as an important link along terrestrial food chains. Here, we investigated the response of earthworms (Eisenia fetida) to three types of multi-layer graphenes (MLGs) (G1, G2 and G3 with 12-15 layers) with variable morphology (lateral sizes: 7.4 ± 0.3, 6.4 ± 0.1 and 2.8 ± 0.1 μm; thicknesses: 5.0 ± 0.1, 4.2 ± 0.1 and 4.0 ± 0.2 nm, respectively) and hydrophobicity ((O + N)/C ratios: 0.029, 0.044 and 0.075; contact angles: 122.8, 118.8 and 115.1°, respectively). Exposure to these materials was conducted for 28 days (except for 48-h avoidance test) separately in potting or farm soil at 0.2% and 1% by weight. Earthworms avoided both soils when amended with 1% of the smaller and more hydrophilic MLGs (G2 and G3), leading to a decreased trend in worm cocoon formation. The smallest and most hydrophilic MLG (G3), which was easier to assimilate, also significantly inhibited the viability (20.2-56.0%) and mitochondrial membrane potential (32.0-48.5%) of worm coelomocytes in both soils. In contrast, oxidative damage (indicated by lipid peroxides) was more pronounced upon exposure to more hydrophobic and larger graphenic materials (G1 and G2), which were attributed to facilitated adhesion to and disruption of worm membranes. These findings highlight the importance of MLG morphology and hydrophobicity in their potential toxicity and mode of action, as well as ecological risks associated with incidental and accidental releases.

Enhancement of Gas Barrier Properties of Graphene Oxide/Poly (Lactic Acid) Films Using a Solvent-free Method

Graphene oxide(GO)/polylactic acid (PLA) nanocomposite, prepared using a solvent-free melt mixing processing, is investigated as a potential oxygen barrier packaging film in this work. In order to disperse GO homogeneously in PLA matrix, hydrophobic silane coupling agent, i.e., γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), is used to modify the graphene oxide sheets. The modified GO is able to be well bonded to the PLA due to the formation of covalent bonds between the epoxy groups of KH560 and the carboxyl and hydroxyl terminal groups of PLA. Furthermore, the thermal stability of GO is enhanced due to the long alkyl side chain of KH560, which could also increase the crystallinity of PLA. As a result, the crystallinity of PLA is significantly improved because of the linear KH560 chains, which can act as nucleating agents to improve the crystallization. The KH560-GO helps to reduce the O₂ permeability of KH560-GO/PLA composite films via a dual-action mechanism: (1) providing physical barrier due to their native barrier properties, and (2) by resulting in higher degree of crystallinity. The as-prepared KH560-GO0.75/PLA is able to exhibit ca. 33% and ca. 13% decrease in the P_O2 than the neat PLA and GO0.75/PLA film, respectively. Finally, the mechanical properties and impact fractured surfaces indicate that the increase in the tensile strength and elongation at break value of KH560-GO/PLA are due to the strong interfacial adhesion and the strong bonding between the epoxy group of KH560-GO and hydroxyl and carboxyl acid terminal groups of PLA matrix.

Graphene Oxide Nanosheets Tailored With Aromatic Dipeptide Nanoassemblies for a Tuneable Interaction With Cell Membranes

Engineered graphene-based derivatives are attractive and promising candidates for nanomedicine applications because of their versatility as 2D nanomaterials. However, the safe application of these materials needs to solve the still unanswered issue of graphene nanotoxicity. In this work, we investigated the self-assembly of dityrosine peptides driven by graphene oxide (GO) and/or copper ions in the comparison with the more hydrophobic diphenylalanine dipeptide. To scrutinize the peptide aggregation process, in the absence or presence of GO and/or Cu²⁺, we used atomic force microscopy, circular dichroism, UV-visible, fluorescence and electron paramagnetic resonance spectroscopies. The perturbative effect by the hybrid nanomaterials made of peptide-decorated GO nanosheets on model cell membranes of supported lipid bilayers was investigated. In particular, quartz crystal microbalance with dissipation monitoring and fluorescence recovery after photobleaching techniques were used to track the changes in the viscoelastic properties and fluidity of the cell membrane, respectively. Also, cellular experiments with two model tumour cell lines at a short time of incubation, evidenced the high potential of this approach to set up versatile nanoplatforms for nanomedicine and theranostic applications.

Next-Generation Sequencing Reveals Differential Responses to Acute versus Long-Term Exposures to Graphene Oxide in Human Lung Cells

Numerous studies have addressed the biological impact of graphene-based materials including graphene oxide (GO), yet few have focused on long-term effects. Here, RNA sequencing is utilized to unearth responses of human lung cells to GO. To this end, the BEAS-2B cell line derived from normal human bronchial epithelium is subjected to repeated, low-dose exposures of GO (1 or 5 µg mL^-1 ) for 28 days or to the equivalent, cumulative amount of GO for 48 h. Then, samples are analyzed by using the NovaSeq 6000 sequencing system followed by pathway analysis and gene ontology enrichment analysis of the differentially expressed genes. Significant differences are seen between the low-dose, long-term exposures and the high-dose, short-term exposures. Hence, exposure to GO for 48 h results in mitochondrial dysfunction. In contrast, exposure to GO for 28 days is characterized by engagement of apoptosis pathways with downregulation of genes belonging to the inhibitor of apoptosis protein (IAP) family. Validation experiments confirm that long-term exposure to GO affects the apoptosis threshold in lung cells, accompanied by a loss of IAPs. These studies reveal the sensitivity of RNA-sequencing approaches and show that acute exposure to GO is not a good predictor of the long-term effects of GO.

Evaluation of nanomaterials to prevent oral Candidiasis in PMMA based denture wearing patients. A systematic analysis

Purpose

The purpose of this study is the prevention of Candida colonies on PMMA Denture Base by altering the surface and incorporations of Nanoparticles.

Materials and methods

The Pub Med/Medline was searched to identify 100 relevant studies published from 2011 to 2020. The search strategy employed the following keywords related to "use of Nanoparticles in dentistry", "Antimicrobial agents and PMMA", "Candidiasis and nanomaterials", "Prevention of oral Candidiasis", "Incorporation of antimicrobial agents in acrylic dentures," "nanoparticles as therapeutic agents for denture stomatitis", "Nanodentistry" or "Nanotechnology" or "Nanocomposite" or "Nanodrugs" or "Nanomaterials".

Results

Most of the studies shows that modified PMMA denture base resin containing different antimicrobial coatings and incorporation of metal oxides Nanoparticles and other nanomaterials showed antifungal activity in vitro; however some materials in higher concentration showing altered physical and mechanical properties possibly due to aggregation of Nanoparticles in the lattice of PMMA molecules.

Conclusion

Metal oxides nanomaterials revealed cytotoxicity to Candida and other microbes present in oral biofilm including PMMA denture surface. Nano toxicity may attribute to direct interaction of nanoparticles with cell membrane, hindrance in protein synthesis and early adhesion & interfere with physiology of pathogens.

Hormesis Effects of Nano- and Micro-sized Copper Oxide

The concerns about the possible risk of manufactured nanoparticles (NPs) have been raised recently. Nano- and micro-sized copper oxide (CO and CONP) are widely used in many industries. In this regard, in-vitro studies have demonstrated that CONP is a toxic compound in different cell lines. Despite their unique properties, NPs possess unexpected toxicity profiling relative to the bulk materials. This study was designed to examine and compare the toxic effects of CO and CONPs in-vivo and in isolated rat mitochondria. Male Wistar albino rats received 50 to 1000 mg/kg CO or CONP by gavage and several toxicological endpoints including biochemical indices and oxidative stress markers. Then, the pathological parameters in the multiple organs such as liver, brain, spleen, kidney, and intestine were assessed. Mitochondria were isolated from the rat liver and several mitochondrial indices were measured. The results of this study demonstrated that CO and CONP exhibited biphasic dose-response effects. CONPs showed higher toxicity compared with the bulk material. There were no significant changes in the results of CONP and CO in isolated rat liver mitochondria. The present studies provided more information regarding the hormetic effects of CO and CONPs in-vivo and in isolated rat mitochondria.

Graphene oxide and reduced graphene oxide-based scaffolds in regenerative medicine

There is a vast and rapid increase in the applications of graphene oxide (GO) and reduced graphene oxide (rGO) in the biomedical field, including drug delivery, bio-sensing, and diagnostic tools. Among all the applications, the GO and rGO-based scaffolds are a very promising system that have attracted attention because of their great clinical projection in tissue regeneration therapies. Both GO and rGO have shown a strong impact on the proliferation and differentiation of implemented stem cells, but still need to overcome several challenges, such as cytotoxicity, biodistribution, biotransformation or immune response. However, there are still controversial hypothesises regarding the mechanisms involved in these issues that should be clarified in order to improve the applications of these compounds. 3D-scaffolds can help in solving some of those limitations when moving into preclinical studies in regenerative medicine. In this review, we will describe the application of GO and rGO within 3D scaffolds in bone, cardiac and neural regenerative medicine after analyzing the aforementioned challenges.

Nanocarrier-Based Therapeutics and Theranostics Drug Delivery Systems for Next Generation of Liver Cancer Nanodrug Modalities

The development of therapeutics and theranostic nanodrug delivery systems have posed a challenging task for the current researchers due to the requirement of having various nanocarriers and active agents for better therapy, imaging, and controlled release of drugs efficiently in one platform. The conventional liver cancer chemotherapy has many negative effects such as multiple drug resistance (MDR), high clearance rate, severe side effects, unwanted drug distribution to the specific site of liver cancer and low concentration of drug that finally reaches liver cancer cells. Therefore, it is necessary to develop novel strategies and novel nanocarriers that will carry the drug molecules specific to the affected cancerous hepatocytes in an adequate amount and duration within the therapeutic window. Therapeutics and theranostic systems have advantages over conventional chemotherapy due to the high efficacy of drug loading or drug encapsulation efficiency, high cellular uptake, high drug release, and minimum side effects. These nanocarriers possess high drug accumulation in the tumor area while minimizing toxic effects on healthy tissues. This review focuses on the current research on nanocarrier-based therapeutics and theranostic drug delivery systems excluding the negative consequences of nanotechnology in the field of drug delivery systems. However, clinical developments of theranostics nanocarriers for liver cancer are considered outside of the scope of this article. This review discusses only the recent developments of nanocarrier-based drug delivery systems for liver cancer therapy and diagnosis. The negative consequences of individual nanocarrier in the drug delivery system will also not be covered in this review.

Graphene oxide disrupts the protein-protein interaction between Neuroligin/NLG-1 and DLG-1 or MAGI-1 in nematode Caenorhabditis elegans

Graphene oxide (GO) is a carbon-based engineered nanomaterial (ENM). Using Caenorhabditis elegans as an animal model, we investigated the effect of GO exposure on protein-protein interactions. In nematodes, NLG-1/Neuroligin, a postsynaptic protein, acted only in the neurons to regulate the GO toxicity. In the neurons, DLG-1, a PSD-95 protein, and MAGI-1, a S-SCAM protein, were identified as the downstream targets of NLG-1 in the regulation of GO toxicity. PKC-1, a serine/threonine protein kinase C, further acted downstream of neuronal DLG-1 and MAGI-1 to regulate the GO toxicity. Co-immunoprecipitation analysis demonstrated the protein-protein interaction between NLG-1 and DLG-1 or MAGI-1. After GO expression, this protein-protein interaction between NLG-1 and DLG-1 or MAGI-1 was significantly inhibited. Therefore, our data raised the evidence to suggest the potential of GO exposure in disrupting protein-protein interactions in organisms.

Dispersed graphene materials of biomedical interest and their toxicological consequences

Graphene is one-atom thick nanocarbon displaying a unique honeycomb structure and extensive conjugation. In addition to high surface area to mass ratio, it displays unique optical, thermal, electronic and mechanical properties. Atomic scale tunability of graphene has attracted immense research interest with a prospective utility in electronics, desalination, energy sectors, and beyond. Its intrinsic opto-thermal properties are appealing from the standpoint of multimodal drug delivery, imaging and biosensing applications. Hydrophobic basal plane of sheets can be efficiently loaded with aromatic molecules via non-specific forces. With intense biomedical interest, methods are evolving to produce defect-free and dispersion stable sheets. This review summarizes advancements in synthetic approaches and strategies of stabilizing graphene derivatives in aqueous medium. We have described the interaction of colloidal graphene with cellular and sub-cellular components, and subsequent physiological signaling. Finally, a systematic discussion is provided covering toxicological challenges and possible solutions on utilizing graphene formulations for high-end biomedical applications.

Graphene oxide-based nanomaterial interaction with human breast cancer cells

Graphene and graphene-based nanomaterials have great potential for various biomedical applications due to their unique physicochemical properties. However, how graphene-based nanomaterials interact with biological systems has not been thoroughly studied. This study shows that 24, 48, and 72 hr exposure of 2.4 μg/cm² of graphene oxide (GOX) and GOX modified with DAB-AM-16 and PAMAM dendrimers (GOXD and GOXP, respectively) did not exhibit toxicity to MCF-7 cells. However, higher graphene concentrations, such as 24 and 48 μg/cm² , induced low cytotoxic effects. The GOX, GOXD, and GOXP particles have a strong affinity with the cellular membrane. Cells that internalized the nanomaterials presented morphological alterations and modifications in the organization of microfilaments and microtubules compared with control cells. Then, cells were treated with 24 μg/cm² of GOX, GOXD or GOXP for 24 hr and recovered for an additional period of 24 hr in normal medium. Nanoparticles remained in the cytoplasm of some cells, apparently with no effect on cellular morphology, being consistent with the data found in the cell proliferation experiment, which showed that the cells remained alive up to 72 hr.

Graphene oxide-induced neurotoxicity on neurotransmitters, AFD neurons and locomotive behavior in Caenorhabditis elegans

Graphene oxide (GO) and graphene-based nanomaterials have been widely applied in recent years, but their potential health risk and neurotoxic potentials remain poorly understood. In this study, neurotoxic potential of GO and its underlying molecular and cellular mechanism were investigated using the nematode, Caenorhabditis elegans. Deposition of GO in the head region and increased reactive oxygen species (ROS) was observed in C. elegans after exposure to GO. The neurotoxic potential of GO was then investigated, focusing on neurotransmitters contents and neuronal activity using AFD sensory neurons. The contents of all neurotransmitters, such as, tyrosine, tryptophan, dopamine, tyramine, and GABA, decreased significantly by GO exposure. Decreased fluorescence of Pgcy-8:GFP, a marker of AFD sensory neuron, by GO exposure suggested GO could cause neuronal damage on AFD neuron. GO exposure led decreased expression of ttx-1 and ceh-14, genes required for the function of AFD neurons also confirmed possible detrimental effect of GO to AFD neuron. To understand physiological meaning of AFD neuronal damage by GO exposure, locomotive behavior was then investigated in wild-type as well as in loss-of-function mutants of ttx-1 and ceh-14. GO exposure significantly altered locomotor behavior markers, such as, speed, acceleration, stop time, etc., in wild-type C. elegans, which were mostly rescued in AFD neuron mutants. The present study suggested the GO possesses neurotoxic potential, especially on neurotransmitters and AFD neuron in C. elegans. These findings provide useful information to understand the neurotoxic potential of GO and other graphene-based nanomaterials, which will guide their safe application.

Effect of electrical stimulation combined with graphene-oxide-based membranes on neural stem cell proliferation and differentiation

The combination of composite nerve materials prepared using degradable polymer materials with biological or physical factors has received extensive attention as a means to treat nerve injuries. This study focused on the potential application of graphene oxide (GO) composite conductive materials combined with electrical stimulation (ES) in nerve repair. A conductive poly(L-lactic-co-glycolic acid) (PLGA)/GO composite membrane was prepared, and its properties were tested using a scanning electron microscope (SEM), a contact angle meter, and a mechanical tester. Next, neural stem cells (NSCs) were planted on the PLGA/GO conductive composite membrane and ES was applied. NSC proliferation and differentiation and neurite elongation were observed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, immunofluorescence, and PCR, respectively. The results showed that the PLGA/GO membrane had good hydrophilicity, mechanical strength, and protein adsorption. ES combined with the PLGA/GO membrane significantly promoted NSC proliferation and neuronal differentiation on the material surface and promoted significant neurite elongation. Our results suggest that ES combined with GO-related conductive composite materials can be used as a new therapeutic combination to treat nerve injuries.

The application of omics-based human liver platforms for investigating the mechanism of drug-induced hepatotoxicity in vitro

Drug-induced liver injury (DILI) complicates safety assessment for new drugs and poses major threats to both patient health and drug development in the pharmaceutical industry. A number of human liver cell-based in vitro models combined with toxicogenomics methods have been developed as an alternative to animal testing for studying human DILI mechanisms. In this review, we discuss the in vitro human liver systems and their applications in omics-based drug-induced hepatotoxicity studies. We furthermore present bioinformatic approaches that are useful for analyzing toxicogenomic data generated from these models and discuss their current and potential contributions to the understanding of mechanisms of DILI. Human pluripotent stem cells, carrying donor-specific genetic information, hold great potential for advancing the study of individual-specific toxicological responses. When co-cultured with other liver-derived non-parenchymal cells in a microfluidic device, the resulting dynamic platform enables us to study immune-mediated drug hypersensitivity and accelerates personalized drug toxicology studies. A flexible microfluidic platform would also support the assembly of a more advanced organs-on-a-chip device, further bridging gap between in vitro and in vivo conditions. The standard transcriptomic analysis of these cell systems can be complemented with causality-inferring approaches to improve the understanding of DILI mechanisms. These approaches involve statistical techniques capable of elucidating regulatory interactions in parts of these mechanisms. The use of more elaborated human liver models, in harmony with causality-inferring bioinformatic approaches will pave the way for establishing a powerful methodology to systematically assess DILI mechanisms across a wide range of conditions.

Exposure to graphene oxide sheets alters the expression of reference genes used for real-time RT-qPCR normalization

Studies unraveling the interactions between graphene oxide (GO) and the biological milieu, including cells and tissues, are multiplying quickly as the biomedical applications of this and other 2D materials continue to be explored. Many of such studies rely on real-time RT-qPCR as a powerful yet simple technique to assess gene expression. However, a systematic investigation of potential GO-induced changes in the expression of reference genes, crucial for appropriate qPCR data normalization, is still lacking. We aimed to cover this gap investigating the stability of the expression of ten candidate reference genes upon exposure to increasing, but subtoxic, GO concentrations, with two established algorithms (Bestkeeper and NormFinder). The study was performed in a human cancer cell line (MCF7) and in mouse, non-cancerous, primary cells (mouse embryonic fibroblasts, MEFs), to assess different behaviors between cell types. Both algorithms evidenced significant deviations in the expression of various reference genes. Ribosomal proteins scored among the most significantly dysregulated in both cell types. ACTB and GAPDH, the most frequent calibrators in real-time RT-qPCR, were also affected, although differences existed between cell lines. This study illustrates the need to validate reference genes for appropriate real-time RT-qPCR normalization, according to specific experimental conditions, when GO-cell interactions occur.

Graphene oxide as a 2D platform for complexation and intracellular delivery of siRNA

The development of efficient and safe nucleic acid delivery vectors remains an unmet need holding back translation of gene therapy approaches to the bedside. Graphene oxide (GO) could help bypass such bottlenecks, thanks to its large surface area, versatile chemistry and biocompatibility, which could overall enhance transfection efficiency while abolishing some of the limitations linked to the use of viral vectors. Here, we aimed to assess the capacity of bare GO, without any further surface modification, to complex a short double-stranded nucleic acid of biological relevance (siRNA) and mediate its intracellular delivery. GO formed stable complexes with siRNA at 10 : 1, 20 : 1 and 50 : 1 GO : siRNA mass ratios. Complexation was further corroborated by atomistic molecular dynamics simulations. GO : siRNA complexes were promptly internalized in a primary mouse cell culture, as early as 4 h after exposure. At this time point, intracellular siRNA levels were comparable to those provided by a lipid-based transfection reagent that achieved significant gene silencing. The time-lapse tracking of internalized GO and siRNA evidenced a sharp decrease of intracellular siRNA from 4 to 12 h, while GO was sequestered in large vesicles, which may explain the lack of biological effects (i.e. gene silencing) achieved by GO : siRNA complexes. This study underlines the potential of non-surface modified GO flakes to act as 2D siRNA delivery platforms, without the need for cationic functionalization, but warrants further vector optimization to allow the effective release of the nucleic acid and achieve efficient gene silencing.

Induction of chromosomal and DNA damage and histological alterations by graphene oxide nanoparticles in Swiss mice

The unique physicochemical properties of graphene oxide (GO) nanoparticles increase their uses in a wide range of applications that increase their release into the environment, and thus human exposure. However, the in vivo clastogenicity and genotoxicity of GO nanoparticles have not been well investigated. The current study was, therefore, designed to investigate the possible induction of chromosomal and DNA damage by GO nanoparticles and their impact on the tissue architecture in mice. Oral administration of GO nanoparticles for one or five consecutive days at the three dose levels 10, 20 or 40 mg/kg significantly increased the micronuclei and DNA damage levels in a dose-dependent manner in mice bone marrow cells, as well as caused, histological lesions including apoptosis, necrosis, inflammations and cells degeneration in the mice liver and brain tissue sections compared to the normal control mice. Thus, we concluded that oral administration of GO nanoparticles induced chromosomal and DNA damage in a dose-dependent manner as well as histological injuries in both acute and subacute treatments.

Nanotoxicity of different sizes of graphene (G) and graphene oxide (GO) in vitro and in vivo

Graphene family nanomaterials (GFNs) have attracted significant attention due to their unique characteristics and applications in the fields of biomedicine and nanotechnology. However, previous studies highlighted the in vitro and in vivo toxicity of GFNs with size and oxidation state differences are still elusive. Therefore, we prepared graphene (G) and graphene oxide (GO) of three different sizes (S-small, M-medium, and L-large), and characterized them using multiple surface-sensitive analytical techniques. In vitro assays using HEK 293T cells revealed that the small and large sizes of G and GO significantly reduced the cell viability and increased DNA damage, accompanying with activated reactive oxygen species (ROS) generation and induced various expressions of associated critical genetic markers. Moreover, the bacterial assays highlighted that G and GO caused strong acute toxicity on Tox2 bacteria. Effects of G were higher than GO and showed size dependent effect: L > M > S, while the medium size of GO induced mild genetic toxicity on RecA bacteria. In vivo assays revealed that exposure to G and GO caused the developmental toxicity, induced ROS generation, and activated related pathways (specifically GO) in zebrafish. Taken together, G showed stronger ability to decrease the survival rate and induce the acute toxicity, while GO showed obvious toxicity in terms of DNA damages, ROS generation, and abnormal gene expressions. Our findings highlighted that G and GO differentially induced toxicity based on their varying physical characteristics, especially sizes and oxidation state, and exposure concentrations and sensitivity of the employed in vitro and in vivo models. In short, this study provided deep insights on the negative effects of GFNs exposure.

A Hybrid Nanoplatform of Graphene Oxide/Nanogold for Plasmonic Sensing and Cellular Applications at the Nanobiointerface

In this study, nanocomposites of spherical gold nanoparticles (AuNPs) and graphene oxide (GO) nanosheets were fabricated by a simple one-step reduction method. The characterisation by UV-visible spectroscopy of the plasmonic sensing properties pointed out to a strong interaction between graphene and metal nanoparticles in the hybrid GO-AuNP, as confirmed by nuclear magnetic resonance. Moreover, atomic force microscopy analyses demonstrated that the gold nanoparticles were mostly confined to the basal planes of the GO sheets. The response of the nanoassemblies at the biointerface with human neuroblastoma SH-SY5Y cell line was investigated in terms of nanotoxicity as well as of total and mitochondrial reactive oxygen species production. Confocal microscopy imaging of cellular internalization highlighted the promising potentialities of GO-AuNP nanoplatforms for theranostic (i.e., sensing/imaging + therapy) applications.

Degradation of Mitochondria and Oxidative Stress as the Main Mechanism of Toxicity of Pristine Graphene on U87 Glioblastoma Cells and Tumors and HS-5 Cells

Due to the development of nanotechnologies, graphene and graphene-based nanomaterials have attracted immense scientific interest owing to their extraordinary properties. Graphene can be used in many fields, including biomedicine. To date, little is known about the impact graphene may have on human health in the case of intentional exposure. The present study was carried out on U87 glioma cells and non-cancer HS-5 cell lines as in vitro model and U87 tumors cultured on chicken embryo chorioallantoic membrane as in vivo model, on which the effects of pristine graphene platelets (GPs) were evaluated. The investigation consisted of structural analysis of GPs using transmission electron microscopy, Fourier transmission infrared measurements, zeta potential measurements, evaluation of cell morphology, assessment of cell viability, investigation of reactive oxygen species production, and investigation of mitochondrial membrane potential. The toxicity of U87 glioma tumors was evaluated by calculating the weight and volume of tumors and performing analyses of the ultrastructure, histology, and protein expression. The in vitro results indicate that GPs have dose-dependent cytotoxicity via ROS overproduction and depletion of the mitochondrial membrane potential. The mass and volume of tumors were reduced in vivo after injection of GPs. Additionally, the level of apoptotic and necrotic markers increased in GPs-treated tumors.

Differential Cytotoxicity of Different Sizes of Graphene Oxide Nanoparticles in Leydig (TM3) and Sertoli (TM4) Cells

Graphene oxide (GO) is an common nanomaterial and has attracted unlimited interest in academia and industry due to its physical, chemical, and biological properties, as well as for its tremendous potential in applications in various fields, including nanomedicine. Whereas studies have evaluated the size-dependent cytotoxicity of GO in cancer cells, there have been no studies on the biological behavior of ultra-small graphene nanosheets in germ cells. To investigate, for the first time, the cyto- and geno- toxic effects of different sizes of GO in two different cell types, Leydig (TM3) and Sertoli (TM4) cells, we synthesized different sized GO nanosheets with an average size of 100 and 20 nm by a modification of Hummers’ method, and characterized them by various analytical techniques. Cell viability and proliferation assays showed significant size- and dose-dependent toxicity with GO-20 and GO-100. Interestingly, GO-20 induced significant loss of cell viability and cell proliferation, higher levels of leakage of lactate dehydrogenase (LDH) and reactive oxygen species (ROS) generation compared to GO-100. Both GO-100 and GO-20 induced significant loss of mitochondrial membrane potential (MMP) in TM3 and TM4 cells, which is a critical factor for ROS generation. Furthermore, GO-100 and GO-20 caused oxidative damage to DNA by increasing the levels of 8-oxo-dG, which is formed by direct attack of ROS on DNA; GO-100 and GO-20 upregulate various genes responsible for DNA damage and apoptosis. We found that phosphorylation levels of EGFR/AKT signaling molecules, which are related to cell survival and apoptosis, were significantly altered after GO-100 and GO-20 exposure. Our results showed that GO-20 has more potent toxic effects than GO-100, and that the loss of MMP and apoptosis are the main toxicity responses to GO-100 and GO-20 treatments, which likely occur due to EGFR/AKT pathway regulation. Collectively, our results suggest that both GO-100 and GO-20 exhibit size-dependent germ cell toxicity in male somatic cells, particularly TM3 cells, which seem to be more sensitive compared to TM4, which strongly suggests that applications of GO in commercial products must be carefully evaluated.

Differential Immunomodulatory Effect of Graphene Oxide and Vanillin-Functionalized Graphene Oxide Nanoparticles in Human Acute Monocytic Leukemia Cell Line (THP-1)

Graphene and its derivatives are emerging as attractive materials for biomedical applications, including antibacterial, gene delivery, contrast imaging, and anticancer therapy applications. It is of fundamental importance to study the cytotoxicity and biocompatibility of these materials as well as how they interact with the immune system. The present study was conducted to assess the immunotoxicity of graphene oxide (GO) and vanillin-functionalized GO (V-rGO) on THP-1 cells, a human acute monocytic leukemia cell line. The synthesized GO and V-rGO were characterized by using various analytical techniques. Various concentrations of GO and V-rGO showed toxic effects on THP-1 cells such as the loss of cell viability and proliferation in a dose-dependent manner. Cytotoxicity was further demonstrated as an increased level of lactate dehydrogenase (LDH), loss of mitochondrial membrane potential (MMP), decreased level of ATP content, and cell death. Increased levels of reactive oxygen species (ROS) and lipid peroxidation caused redox imbalance in THP-1 cells, leading to increased levels of malondialdehyde (MDA) and decreased levels of anti-oxidants such as glutathione (GSH), glutathione peroxidase (GPX), super oxide dismutase (SOD), and catalase (CAT). Increased generation of ROS and reduced MMP with simultaneous increases in the expression of pro-apoptotic genes and downregulation of anti-apoptotic genes suggest that the mitochondria-mediated pathway is involved in GO and V-rGO-induced apoptosis. Apoptosis was induced consistently with the significant DNA damage caused by increased levels of 8-oxo-dG and upregulation of various key DNA-regulating genes in THP-1 cells, indicating that GO and V-rGO induce cell death through oxidative stress. As a result of these events, GO and V-rGO stimulated the secretion of various cytokines and chemokines, indicating that the graphene materials induced potent inflammatory responses to THP-1 cells. The harshness of V-rGO in all assays tested occurred because of better charge transfer, various carbon to oxygen ratios, and chemical compositions in the rGO. Overall, these findings suggest that it is essential to better understand the parameters governing GO and functionalized GO in immunotoxicity and inflammation. Rational design of safe GO-based formulations for various applications, including nanomedicine, may result in the development of risk management methods for people exposed to graphene and graphene family materials, as these nanoparticles can be used as delivery agents in various biomedical applications.

Graphene oxide down-regulates genes of the oxidative phosphorylation complexes in a glioblastoma

BACKGROUND

Recently different forms of nanographene were proposed as the material with high anticancer potential. However, the mechanism of the suppressive activity of the graphene on cancer development remains unclear. We examined the effect of oxygenated, reduced and pristine graphene on the gene expression in glioblastoma U87 cell line.

RESULTS

Conducting microarrays and RT-qPCR analysis we explored that graphene oxide (rather than reduced graphene oxide and pristine graphene) down-regulates the mRNA expression of mitochondrial oxidative phosphorylation (OXPHOS) nuclear genes of complexes I, III, IV and V. The presented results provide first evidence for the hypothesis that the suppressed growth of GBM can be the consequence of down-regulation of OXPHOS protein expression and decreased ATP level.

CONCLUSIONS

We suggest that changes in the expression of OXPHOS genes identified in our study may mediate the anti-proliferative and anti-migratory effects of graphene oxide in glioblastoma cells. However, further investigations with different cell lines, regarding expression, regulation and activity of OXPHOS genes identified in our study is necessary to elucidate the mechanism mediating the anti-proliferative and anti-migratory effects of graphene oxide in glioblastoma cells.

Necrotic, apoptotic and autophagic cell fates triggered by nanoparticles

Nanomaterials have gained a rapid increase in use in a variety of applications that pertain to many aspects of human life. The majority of these innovations are centered on medical applications and a range of industrial and environmental uses ranging from electronics to environmental remediation. Despite the advantages of NPs, the knowledge of their toxicological behavior and their interactions with the cellular machinery that determines cell fate is extremely limited. This review is an attempt to summarize and increase our understanding of the mechanistic basis of nanomaterial interactions with the cellular machinery that governs cell fate and activity. We review the mechanisms of NP-induced necrosis, apoptosis and autophagy and potential implications of these pathways in nanomaterial-induced outcomes. Abbreviations: Ag, silver; CdTe, cadmium telluride; CNTs, carbon nanotubes; EC, endothelial cell; GFP, green fluorescent protein; GO, graphene oxide; GSH, glutathione; HUVECs, human umbilical vein endothelial cells; NP, nanoparticle; PEI, polyethylenimine; PVP, polyvinylpyrrolidone; QD, quantum dot; ROS, reactive oxygen species; SiO2, silicon dioxide; SPIONs, superparamagnetic iron oxide nanoparticles; SWCNT, single-walled carbon nanotubes; TiO2, titanium dioxide; USPION, ultra-small super paramagnetic iron oxide; ZnO, zinc oxide.