Toxicity of graphene-family nanoparticles: a general review of the origins and mechanisms

Astrocyte responses to nanomaterials: Functional changes, pathological changes and potential applications

Astrocytes are responsible for regulating and optimizing the functional environment of neurons in the brain and can reduce the adverse impacts of external factors by protecting neurons. However, excessive astrocyte activation upon stimulation may alter their initial protective effect and actually lead to aggravation of injury. Similar to the dual effects of astrocytes in the response to injury within the central nervous system (CNS), nanomaterials (NMs) can have either toxic or beneficial effects on astrocytes, serving to promote injury or inhibit tumors. As the important physiological functions of astrocytes have been gradually revealed, the effects of NMs on astrocytes and the underlying mechanisms have become a new frontier in nanomedicine and neuroscience. This review summarizes the in vitro and in vivo findings regarding the effects of various NMs on astrocytes, focusing on functional alterations and pathological processes in astrocytes, as well as the possible underlying mechanisms. We also emphasize the importance of co-culture models in studying the interaction between NMs and cells of the CNS. Finally, we discuss NMs that have shown promise for application in astrocyte-related diseases and propose some challenges and suggestions for further investigations, with the aim of providing guidance for the widespread application of NMs in the CNS.

An assessment of the reproductive toxicity of GONPs exposure to Bombyx mori

This study aimed to explore the toxicity of environmental residues of graphene oxide nanoparticles (GONPs) to reproduction of Lepidopteron insects using both ovary cell line (BmN) and individual female Bombyx mori as the research subjects. The results showed that GONPs dose dependently affect BmN cells. At higher concentrations (>25 mg/L), GONPs led to oxidative stress, ROS accumulation and DNA damage in BmN cells and significantly reduced their survival rate (p ≤ 0.05). Moreover, feeding female B. mori larvae with mulberry leaves treated with 25 mg/L GONPs significantly decreased their gonadosomatic index (GSI) by 40.84%, and increased oxidation levels and antioxidant enzyme activity in silkworm ovary tissues. Pathological analysis found that exposure to GONPs decreased the numbers of both oogonia and oocytes in ovarian tissues, increased the formation of peroxisome and vacuoles in follicle cells, reduced the transcription of genes (Vg, Ovo, Sxl-s, Sxl-l, and Otu) related to ovarian development in B. mori by 0.61, 0.65, 0.75, 0.72, and 0.42-fold, respectively, and lowered the amount of spawning by 52.25%. Overall, these results revealed that GONPs exposure is toxic to the reproduction of B. mori. The underlying mechanism is that oxidative stress due to GONPs causes oxidative damage to DNA, damages ovarian tissues, as well as hinders B. mori development and spawning. Thus, this study provides important experimental data for safety evaluation of reproductive toxicity due to GONPs exposure.

Oxidative stress in Ruditapes philippinarum after exposure to different graphene oxide concentrations in the presence and absence of sediment

The use of carbon nanomaterials (CNMs) is growing in different technological fields, raising concern on their potential impacts on the environment. Given its diverse nanothenological applications, graphene oxide (GO) stands out among the most widely used CNMs. Its hydrophilic capacity enables it to remain stable in suspension in water allowing that GO can be accessible for accumulation by aquatic organisms through ingestion, filtration and superficial dermal contact when present in aquatic ecosystems. Considering that the effects induced to aquatic organisms may depend on environment characteristics, such as temperature, salinity, water pH as well as the presence/absence of sediment, the present study aimed to investigate the influence of sediment on the impacts caused by GO exposure. For this, oxidative stress parameters were measured in the clam Ruditapes philippinarum, exposed to different GO concentrations (0.01, 0.1 and 1 mg/L), in the presence and absence of sediment, for a 28-days experimental period. The results here presented showed that regardless the presence or absence of sediment, most of the biochemical parameters considered were altered when clams were exposed to the highest concentration. The present findings further revealed that in the presence of sediment, clams mostly invested in non-enzymatic defenses (such as reduced glutathione, GSH), while animals exposed to GO in the absence of sediment favored their enzymatic antioxidant defense capacity (catalase, CAT and superoxide dismutase, SOD). This study highlights the relevance of environmental variations as key factors influencing organisms' responses to pollutants.

Tantalum Particles Induced Cytotoxic and Inflammatory Effects in Human Monocytes

The aim of this study is to evaluate the biological safety of tantalum (Ta) particles and to further explore the effects of Ta particles on human monocyte toxicity and inflammatory cytokine expression. Human monocyte leukemia (THP-1) cells were cultured with Ta and hydroxyapatite (HA) particles. Cell counting kit-8 method was used to evaluate the cytotoxicity of Ta and HA particles. The apoptosis effects were evaluated by flow cytometry, and the protein expression levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were evaluated by ELISA. The protein levels of inflammation-related signaling pathways including nuclear factor-kappa B (NF-κB) and extracellular regulated kinase (ERK) were detected by western blotting. The cytotoxicity test showed that the toxicity level of Ta in vitro was grade l, which is within the clinically acceptable range. Compared with the HA control, Ta had no significant effect on THP-1 cell apoptosis, IL-6, and TNF-α release. The phosphorylated levels of NF-κB and ERK at 3 h in the Ta group were lower than those in the HA and control groups (P < 0.001 both). These results reveal Ta particles behave good biosafety properties and provide some new insights for the future clinical use of Ta.

Antibacterial and antibiofilm properties of graphene and its derivatives

Infections resulting from bacteria and biofilms have become a huge problem threatening human health. In recent years, the antibacterial and antibiofilm effects of graphene and its derivatives have been extensively studied. However, there continues to be some controversy over whether graphene and its derivatives can resist infection and biofilms. Moreover, the antibacterial mechanism and cytotoxicity of graphene and its derivatives are unclear. In the present review, antibacterial and antibiofilm abilities of graphene and its derivatives in solution, on the surface are reviewed, and their toxicity and possible mechanisms are also reviewed. Furthermore, we propose possible future development directions for graphene and its derivatives in antibacterial and antibiofilm applications.

Effect of biomass immobilization and reduced graphene oxide on the microbial community changes and nitrogen removal at low temperatures

The slow growth rate and high optimal temperatures for the anaerobic ammonium oxidation (anammox) bacteria are significant limitations of the anammox processes application in the treatment of mainstream of wastewater entering wastewater treatment plant (WWTP). In this study, we investigate the nitrogen removal and microbial community changes in sodium alginate (SA) and sodium alginate–reduced graphene oxide (SA-RGO) carriers, depending on the process temperature, with a particular emphasis on the temperature close to the mainstream of wastewater entering the WWTP. The RGO addition to the SA matrix causes suppression of the beads swelling, which intern modifies the mechanical properties of the gel beads. The effect of the temperature drop on the nitrogen removal rate was reduced for biomass entrapped in SA and SA-RGO gel beads in comparison to non-immobilized biomass, this suggests a ‘‘protective” effect caused by immobilization. However, analyses performed using next-generation sequencing (NGS) and qPCR revealed that the microbial community composition and relative gene abundance changed significantly, after the implementation of the new process conditions. The microbial community inside the gel beads was completely remodelled, in comparison with inoculum, and denitrification contributed to the nitrogen transformation inside the beads.

Unmodified Clay Nanosheets at the Air-Water Interface

Quasi-two-dimensional (2D) nanolayers, such as graphene oxide or clay layers, adhere to gas-liquid or liquid-liquid interfaces. Particularly, clays are of wide general interest in this context because of their extensive and crucial use as Pickering emulsion stabilizers, as well as for their ability to provide colloidosome capsules. So far, clays could only be localized at oil-water or air-saline-water interfaces in aggregated states, while our results now show that clay nanosheets without any modification can be located at air-deionized-water interfaces. The clay mineral used in the present work is synthetic fluorohectorite with a very high aspect ratio and superior quality in homogeneity and charge distribution compared to other clay minerals. This clay mineral is more suitable for achieving unmodified clay anchoring to fluid interfaces compared to other clay minerals used in previous works. In this context, we studied clay nanosheet organization at the air-water interface by combining different experimental methods: Langmuir-Blodgett trough studies, scanning electron microscopy (SEM) studies of film deposits, grazing-incidence X-ray off-specular scattering (GIXOS), and Brewster angle microscopy (BAM). Clay films formed at the air-water interface could be transferred to solid substrates by the Langmuir-Schaefer method. The BAM results indicate a dynamic equilibrium between clay sheets on the interface and in the subphase. Because of this dynamic equilibrium, the Langmuir monolayer surface pressure does not change significantly when pure clay sheets are spread on the liquid surface. However, also, GIXOS results confirm that there are clay nanosheets at the air-water interface. In addition, we find that clay sheets modified by a branched polymer are much more likely to be confined to the interface.

Transcriptomic analysis suggested the involvement of impaired lipid droplet biogenesis in graphene oxide-induced cytotoxicity in human umbilical vein endothelial cells

Previous studies revealed that direct contact with graphene oxide (GO) induced cytotoxic effects, but the importance of involvement of metabolic pathways, in particular lipid metabolism pathways, might be overlooked. In this study, human umbilical vein endothelial cells (HUVECs) were exposed to GO with large size (denoted as GO-L) or small size (denoted as GO-S), and transcriptomics were used to understand the mechanisms of cytotoxicity of GO at systemic levels. It was shown that GO-L more significantly induced cytotoxicity compared with GO-S. Transcriptomic analysis revealed that compared with GO-S, GO-L had larger impact on gene ontology terms related with mitochondrial function as well as Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related with cell death and growth. But GO-S showed greater influence on KEGG pathways related with lipid metabolism. Both types of GO showed minimal impact on oxidative stress but increased de novo lipogenesis protein fatty acid synthase (FASN). However, only GO-S significantly promoted acyl-CoA synthetase 3 (ACSL3), a key enzyme responsible for esterification of free fatty acids and lipid droplet biogenesis. Not surprisingly, GO-L but not GO-S impaired lipid droplet biogenesis, and increasing lipid levels by oleic acid or α-linolenic acid reduced the cytotoxicity of GO-L to HUVECs. Combined, the results from this study suggested that impaired lipid droplet biogenesis was involved in GO-induced cytotoxicity in HUVECs, and inducing lipid droplet biogenesis could prevent the cytotoxicity of GO.

Altered gut microbiome accompanying with placenta barrier dysfunction programs pregnant complications in mice caused by graphene oxide

The wide use of graphene oxide (GO) has raised increasing concerns about the potential risks to environmental and human health. Recent studies have shown the vital role of gut microbiome in various pathological status or even exogenous exposure, but more detailed understanding about the effects of possible gut microbiome alterations under GO exposure on reproductive toxicology evaluations in pregnant mammals remained elusive. Here we found that orally administrated GO daily during gestational day (GD) 7-16 caused dose-dependent pregnant complications of mice on the endpoint (GD19), including decreased weight of dam and live fetus, high rate of resorbed embryos and dead fetus, and skeletal development retardation. Meanwhile in placenta tissues of pregnant mice exposed to GO at dose over 10 mg/kg, the expression levels of tight junctions (Claudin1 and Occludin) and vascular endothelial growth factor (VEGFA) decreased approximately by 30%-80%, meaning impaired placenta barrier. According to the data of fecal 16s RNA sequencing in 40 mg/kg dose group and the control group, gut microbiome showed dramatically decreased α- and β-diversity, and upregulated Firmicutes/Bacteroidetes ratio owing to GO exposure. What's more, significantly differentiated abundance of Euryarchaeota is expected to be a special biomarker for failed pregnancy caused by GO. Notably, the result of Spearman correlation analysis suggested that there was a strong link (correlation coefficient>0.6) between perturbed gut microbiome with both abnormally expressed factors of placenta barrier and adverse pregnant outcomes. In summary, the damages of GO exposure to placenta barrier and pregnancy were dose-dependent. And GO exposure was responsible for gut microbiome dysbiosis in mice with pregnant complications. These findings could provide referable evidence to evaluate reproductive risk of GO to mammals.

Recent advances in the adsorptive remediation of wastewater using two-dimensional transition metal carbides (MXenes): a review

MXenes, since their discovery in 2011, have garnered significant research attention for a variety of applications due to their exciting physico-chemical properties.

Design of graphenic nanocomposites containing chitosan and polyethylene glycol for spinal cord injury improvement

Advanced therapeutic strategies include the incorporation of biomaterials, which has been identified as an effective method in treating unsolved diseases, such as spinal cord injury. During the acute phase, cascade responses involving cystic cavitation, fibrous glial scar formation, and myelin-associated dissuasive accumulation occur in the microenvironment of the spinal cord lesion. Graphene oxide (GO)-based materials, due to their extraordinary chemical, electrical and mechanical properties and easy to modify structure, are considered as rising stars in biomaterial and tissue engineering. In order to enhance the biodegradability and biocompatibility of GO, cell proliferation may be appropriately designed and situated at the lesion site. In this study, chitosan (CS) and polyethylene glycol (PEG) were grafted onto GO sheets. CS is a natural non-toxic polymer with good solubility and high biocompatible potential that has been used as an anti-inflammatory and anti-oxidant agent. Furthermore, PEG, a synthetic neuroprotective polymer, was used to develop the pharmacokinetic activity and reduce the toxicity of GO. Herein we report a novel nanocomposite consisting of PEG and CS with a potential advantage in spinal tissue regeneration. The preliminary in vitro study on mesenchymal stem cells (MSCs) has demonstrated that the prepared nanocomposites are not only non-toxic but also increase (by nearly 10%) cell growth. Finally, the use of mixed nanocomposites in the spinal cord injury (SCI) model resulted in good repair and inflammation decline after two weeks, such that walking and functional recovery scores of the hind limbs of mice were improved by an average of 6 points in the treatment group.

Herein we report a novel nanocomposite consisting of PEG and CS with a potential advantage in spinal tissue regeneration.

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.

Quantifying respiratory tract deposition of airborne graphene nanoplatelets: The impact of plate-like shape and folded structure

The booming development of commercial products containing graphene nanoplatelets (GNPs) triggers growing concerns over their release into the air. Precise prediction of human respiratory system deposition of airborne GNPs, especially in alveolar region, is very important for inhalation exposure assessment. In this study, the pulmonary deposition of airborne GNPs was predicted by the multiple-path particle dosimetry (MPPD) model with consideration of GNPs plate-like shape and folded structure effect. Different equivalent diameters of GNPs were derived and utilized to describe different deposition mechanisms in the MPPD model. Both of small GNPs (geometric lateral size d_g < 0.1 μm) and large GNPs (d_g > 10 μm) had high deposition fractions in human respiratory system. The total deposition fractions for 0.1 and 30 μm GNPs were 41.6% and 75.6%, respectively. Most of the small GNPs deposited in the alveolar region, while the large GNPs deposited in the head airways. The aerodynamic diameter of GNPs was much smaller than the geometric lateral dimension due to the nanoscale thickness. For GNPs with geometric lateral size of 30 μm, the aerodynamic diameter was 2.98 μm. The small aerodynamic diameter of plate-like GNPs enabled deposition in the alveolar region, and folded GNPs had higher alveolar deposition than planar GNPs. Heavy breathing led to higher GNPs deposition fraction in head airways and lower deposition fractions in the alveolar region than resting breathing.

Occupational exposure to graphene and silica nanoparticles. Part II: pilot study to identify a panel of sensitive biomarkers of genotoxic, oxidative and inflammatory effects on suitable biological matrices

The available biomonitoring studies on workers producing/handling nanomaterials (NMs) focused on potential effects on respiratory, immune and cardio-vascular system. Aim of this study was to identify a panel of sensitive biomarkers and suitable biological matrices to evaluate particularly genotoxic and oxidative effects induced on workers unintentionally exposed to graphene or silica nanoparticles during the production process. These nanomaterials have been chosen for 'NanoKey' project, integrating the workplace exposure assessment (reported in part I) with the biomonitoring of exposed workers reported in the present work. Simultaneously to workplace exposure characterization, we monitored the workers using: Buccal Micronucleus Cytome (BMCyt) assay, fpg-comet test (lymphocytes), oxidized DNA bases 8-oxoGua, 8-oxoGuo and 8-oxodGuo measurements (urine), analysis of oxidative stress biomarkers in exhaled breath condensate (EBC), FENO measurement and cytokines release detection (serum). Since buccal cells are among the main targets of NM occupational exposure, particular attention was posed to the BMCyt assay that represents a noninvasive assay. This pilot study, performed on 12 workers vs.11 controls, demonstrates that BMCyt and fpg-comet assays are the most sensitive biomarkers of early, still reparable, genotoxic and oxidative effects. The findings suggest that these biomarkers could represent useful tools for the biomonitoring of workers exposed to nanoparticles, but they need to be confirmed on a high number of subjects. However, such biomarkers don't discriminate the effects of NM from those due to other chemicals used in the NM production process. Therefore, they could be suitable for the biomonitoring of workers exposed to complex scenario, including nanoparticles exposure.

Melanin-loaded CpG DNA hydrogel for modulation of tumor immune microenvironment

Photothermal immunotherapy has emerged as one of the most potent approaches for cancer treatment, but this strategy has suffered from the lack of biodegradability of the photoresponsive materials. In this study, we aimed to develop biodegradable materials for photothermal immunotherapy. To this end, we designed a DNA CpG hydrogel (DH, generated by rolling-circle amplification), loaded it with bis-(3'-5')-cyclic dimeric guanosine monophosphate (G/DH), and coated the formulation with melanin (Mel/G/DH). Mel/G/DH exhibited a temperature increase upon near infrared (NIR) illumination. In vitro, Mel/G/DH plus NIR (808 nm) irradiation, induced the exposure of calreticulin on CT26 cancer cells, and significantly activated the maturation of dendritic cells (DC). In vivo, local administration of Mel/G/DH (+NIR) exerted photothermal killing of primary tumors and induced maturation of DC in lymph nodes. Treatment of primary tumors with Mel/G/DH(+NIR) prevented the growth of rechallenged tumors at a distant site. Survival was 100% in mice treated with Mel/G/DH(+NIR), 5-fold higher than the group treated with Mel/G(+NIR). Mel/G/DH(+NIR) treatment remodeled the immune microenvironment of distant tumors, increasing cytotoxic T cells and decreasing Treg cells. Taken together, the results of this study suggest the potential of Mel/G/DH as a platform for modulating tumor immune microenvironment aimed at preventing the recurrence of distant tumors.

Graphene Oxide Coatings as Tools to Prevent Microbial Biofilm Formation on Medical Device

The clinical challenge on surface engineering of medical devices to prevent microorganisms adhesion and biofilm formation, has become an essential aspect for medical implants. Antibacterial properties of Graphene Oxide (GO) have been demonstrated across a broad spectrum of bacteria, and the different mechanisms of action with which this nanomaterial interacts with the microbial surface have been elucidated in detail. Innovative protective coatings based on graphene film and hydrogel could represent an innovative solution for the prevention of nosocomial pathogens colonization on implantable device. This brief review mainly focuses on the applications of graphene in nanomedicine with a particular deepening on the antibacterial properties of GO and GO-based nanomaterials. In order to evaluate the possible future applications of GO as an anti-biofilm coating material for medical devices, studies on the ability of graphene coated surface to prevent microbial adhesion are also discussed. A concise review on in vitro toxicity and in vivo safety is also presented.

Encapsulation of Graphene in the Hydrophobic Core of a Lipid Bilayer

Theoretical simulations have predicted that a lipid bilayer forms a stable superstructure when a sheet of graphene is inserted in its hydrophobic core. We experimentally produced for the first time a lipid-graphene-lipid assembly by combining the Langmuir-Blodgett and the Langmuir-Schaefer methods. Graphene is sandwiched and remains flat within the hydrophobic core of the lipid bilayer. Using infrared spectroscopy, ellipsometry, and neutron reflectometry, we characterized the superstructure at every fabrication step. The hybrid superstructure is mechanically stable and graphene does not disturb the natural lipid bilayer structure.

Nanomaterial Additives for Fabrication of Stimuli-Responsive Skeletal Muscle Tissue Engineering Constructs

Volumetric muscle loss necessitates novel tissue engineering strategies for skeletal muscle repair, which have traditionally involved cells and extracellular matrix-mimicking scaffolds and have thus far been unable to successfully restore physiologically relevant function. However, the incorporation of various nanomaterial additives with unique physicochemical properties into scaffolds has recently been explored as a means of fabricating constructs that are responsive to electrical, magnetic, and photothermal stimulation. Herein, several classes of nanomaterials that are used to mediate external stimulation to tissue engineered skeletal muscle are reviewed and the impact of these stimuli-responsive biomaterials on cell growth and differentiation and in vivo muscle repair is discussed. The degradation kinetics and biocompatibilities of these nanomaterial additives are also briefly examined and their potential for incorporation into clinically translatable skeletal muscle tissue engineering strategies is considered. Overall, these nanomaterial additives have proven efficacious and incorporation in tissue engineering scaffolds has resulted in enhanced functional skeletal muscle regeneration.

Nanoparticle-Based Devices in the Control of Antibiotic Resistant Bacteria

Antimicrobial resistance (AR) is one of the most important public health challenges worldwide as it represents a serious complication that is able to increase the mortality, morbidity, disability, hospital stay and economic burden related to infectious diseases. As such, the spread of AR–pathogens must be considered as an emergency, and interdisciplinary approaches must be undertaken in order to develop not only drugs, but holistic strategies to undermine the epidemic and pathogenic potentials of multi-drug resistant (MDR) pathogens. One of such approaches has focused on the use of antimicrobial nanoparticles (ANPs), as they have demonstrated to possess strong antimicrobial effects on MDR pathogens. On the other hand, the ability of bacteria to develop resistance to such agents is minimal. In this way, ANPs may seem a good choice for the development of new drugs, but there is no certainty about their safety, which may delay its translation to the clinical setting. As MDR pathogens are quickly becoming more prevalent and drug development is slow and expensive, there is an increasing need for the rapid development of new strategies to control such agents. We hereby explore the possibility of designing ANP-based devices such as surgical masks and fabrics, wound dressings, catheters, prostheses, dentifrices, water filters, and nanoparticle-coated metals to exploit the potential of such materials in the combat of MDR pathogens, with a good potential for translation into the clinical setting.

Response of DBL-1/TGF-β signaling-mediated neuron-intestine communication to nanopolystyrene in nematode Caenorhabditis elegans

TGF-β signaling pathway is important for the regulation of stress response in organisms. We here used Caenorhabditis elegans to determine the function of DBL-1/TGF-β signaling pathway in the control of response to nanopolystyrene (100 nm). In DBL-1/TGF-β signaling pathway, exposure to 1-1000 μg/L nanopolystyrene significantly increased the expressions of dbl-1 encoding a TGF-β ligand, sma-6 encoding a TGF-β receptor, sma-4 encoding a Co-Smad, and two genes (mab-31 and sma-9) encoding transcriptional factors. DBL-1 acted in the neurons to control the response to nanopolystyrene. In the neurons, the expression and the function of DBL-1 were under the control of two signaling cascades (SMOC-1-ZAG-1 and SMOC-1-ADT-2). TGF-β receptor SMA-6 acted in the intestine to control the response to nanopolystyrene. The downstream Co-Smad/SMA-4 and two transcriptional factors (MAB-31 and SMA-9) of SMA-6 in the intestine were further identified to be required for the control of response to nanopolystyrene. In nanopolystyrene exposed nematodes, intestinal MAB-31 activated the mitochondrial Mn-SOD/SOD-3 by modulating DAF-16 activity, and intestinal SMA-9 activated the mitochondrial unfolded protein response by affecting ELT-2 activity. Therefore, the DBL-1/TGF-β signaling pathway mediated an important neuron-intestine communication in nanopolystyrene exposed nematodes.

Two-dimensional materials in biomedical, biosensing and sensing applications

Two-dimensional (2D) materials are at the forefront of materials research. Here we overview their applications beyond graphene, such as transition metal dichalcogenides, monoelemental Xenes (including phosphorene and bismuthene), carbon nitrides, boron nitrides along with transition metal carbides and nitrides (MXenes). We discuss their usage in various biomedical and environmental monitoring applications, from biosensors to therapeutic treatment agents, their toxicity and their utility in chemical sensing. We highlight how a specific chemical, physical and optical property of 2D materials can influence the performance of bio/sensing, improve drug delivery and photo/thermal therapy as well as affect their toxicity. Such properties are determined by crystal phases electrical conductivity, degree of exfoliation, surface functionalization, strong photoluminescence, strong optical absorption in the near-infrared range and high photothermal conversion efficiency. This review conveys the great future of all the families of 2D materials, especially with the expanding 2D materials' landscape as new materials emerge such as germanene and silicene.

Clay nanolayer encapsulation, evolving from origins of life to future technologies

Clays are the siblings of graphite and graphene/graphene-oxide. There are two basic ways of using clays for encapsulation of sub-micron entities such as molecules, droplets, or nanoparticles, which is either by encapsulation in the interlayer space of clay nanolayered stacked particles ("the graphite way"), or by using exfoliated clay nanolayers to wrap entities in packages ("the graphene way"). Clays maybe the prerequisites for life on earth and can also be linked to the natural formation of other two-dimensional materials such as naturally occurring graphite and its allotropes. Here we discuss state-of-the-art in the area of clay-based encapsulation and point to some future scientific directions and technological possibilities that could emerge from research in this area.

The impact of curcumin-graphene based nanoformulation on cellular interaction and redox-activated apoptosis: An in vitro colon cancer study

Natural plants derivatives have gained enormous merits in cancer therapy applications upon formulation with nanomaterials. Curcumin, as a popular research focus has acquired such improvements surpassing its disadvantageous low bioavailability. To this point, the available research data had confirmed the importance of nanomaterial type in orienting cellular response and provoking different toxicological and death mechanisms that may range from physical membrane damage to intracellular changes. This in turn underlines the poorly studied field of nanoformulation interaction with cells as the key determinant in toxicology outcomes. In this work, curcumin-AuNPs-reduced graphene oxide nanocomposite (CAG) was implemented as a model, to study the impact on cellular membrane integrity and the possible redox changes using colon cancer in vitro cell lines (HT-29 and SW-948), representing drug-responsive and resistant subtypes. Morphological and biochemical methods of transmission electron microscopy (TEM), apoptosis assay, reactive oxygen species (ROS) and antioxidants glutathione and superoxide dismutase (GSH and SOD) levels were examined with consideration to suitable protocols and vital optimizations. TEM micrographs proved endocytic uptake with succeeding cytoplasm deposition, which unlike other nanomaterials studied previously, conserved membrane integrity allowing intracellular cytotoxic mechanism. Apoptosis was confirmed with gold-standard morphological features observed in micrographs, while redox parameters revealed a time-dependent increase in ROS accompanied with regressive GSH and SOD levels. Collectively, this work demonstrates the success of graphene as a platform for curcumin intracellular delivery and cytotoxicity, and further highlights the importance of suitable in vitro methods to be used for nanomaterial validation.

Theoretical Evaluation of DNA Genotoxicity of Graphene Quantum Dots: A Combination of Density Functional Theory and Molecular Dynamics Simulations

Owing to their unique morphology, ultrasmall lateral sizes, and exceptional properties, graphene quantum dots (GQDs) hold great potential in many applications, especially in the fields of electrochemical biosensors, bioimaging, drug delivery, gene delivery, etc. Their biosafety and potential genotoxicity to human and animal cells have been a growing concern in recent years. Especially, the potential DNA damage caused by GQDs is very crucial but still unclear. In this study, the effect of GQDs on DNA damage has been evaluated by a combination of molecular dynamics (MD) simulations and density functional theory. Our results demonstrate that the DNA damaging mechanism of GQDs depends on the size of GQDs. The small GQDs (seven benzene rings) tend to enter into the interior of DNA molecules and cause a DNA base mismatch. The relatively large GQDs (61 benzene rings) tend to adsorb onto the two ends of a DNA molecule and cause DNA unwinding. Due to the strong interaction between guanine (G) and GQDs, the effect of GQDs is much larger on G than on the other three bases (A, C, and T). In addition, the concentration of GQDs could also affect the results of DNA damaging.

Graphene oxide and electroactive reduced graphene oxide-based composite fibrous scaffolds for engineering excitable nerve tissue

This study systematically investigates the role of graphene oxide (GO) and reduced GO (rGO)/silk-based composite micro/nano-fibrous scaffolds in regulating neuronal cell behavior in vitro, given the limited comparative studies on the effects of graphene family materials on nerve regeneration. Fibrous scaffolds can mimic the architecture of the native extracellular matrix and are potential candidates for tissue engineering peripheral nerves. Silk/GO micro/nano-fibrous scaffolds were electrospun with GO loadings 1 to 10 wt.%, and optionally post-reduced in situ to explore a family of electrically conductive non-woven silk/rGO scaffolds. Conductivities up to 4 × 10^-5 S cm^-1 were recorded in the dry state, which increased up to 3 × 10^-4 S cm^-1 after hydration. Neuronoma NG108-15 cells adhered and were viable on all substrates. Enhanced metabolic activity and proliferation were observed on the GO-containing scaffolds, and these cell responses were further promoted for electroactive silk/rGO. Neurite extensions up to 100 μm were achieved by day 5, with maximum outgrowth up to ~250 μm on some of the conductive substrates. These electroactive composite fibrous scaffolds exhibit potential to enhance the neuronal cell response and could be versatile supportive substrates for neural tissue engineering applications.

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.

Adsorption, degradation, and mineralization of emerging pollutants (pharmaceuticals and agrochemicals) by nanostructures: a comprehensive review

This review discusses a fresh pool of research findings reported on the multiple roles played by metal-based, magnetic, graphene-type, chitosan-derived, and sonicated nanoparticles in the treatment of pharmaceutical- and agrochemical-contaminated waters. Some main points from this review are as follows: (i) there is an extensive number of nanoparticles with diverse physicochemical and morphological properties which have been synthesized and then assessed in their respective roles in the degradation and mineralization of many pharmaceuticals and agrochemicals, (ii) the exceptional removal efficiencies of graphene-based nanomaterials for different pharmaceuticals and agrochemicals molecules support arguably well a high potential of these nanomaterials for futuristic applications in remediating water pollution issues, (iii) the need for specific surface modifications and functionalization of parent nanostructures and the design of economically feasible production methods of such tunable nanomaterials tend to hinder their widespread applicability at this stage, (iv) supplementary research is also required to comprehensively elucidate the life cycle ecotoxicity characteristics and behaviors of each type of engineered nanostructures seeded for remediation of pharmaceuticals and agrochemicals in real contaminated media, and last but not the least, (v) real wastewaters are extremely complex in composition due to the mix of inorganic and organic species in different concentrations, and the presence of such mixed species have different radical scavenging effects on the sonocatalytic degradation and mineralization of pharmaceuticals and agrochemicals. Moreover, the formulation of viable full-scale implementation strategies and reactor configurations which can use multifunctional nanostructures for the effective remediation of pharmaceuticals and agrochemicals remains a major area of further research.

Graphene nanosheets damage the lysosomal and mitochondrial membranes and induce the apoptosis of RBL-2H3 cells

The induced membrane damage is a key mechanism for the cytotoxicity of graphene nanosheets (GNSs). In this research, the physical interaction of GNSs on model membranes was investigated using artificial membranes and plasma membrane vesicles. The effects of the GNSs on plasma membrane, lysosomal and mitochondrial membranes were investigated using rat basophilic leukemia (RBL2H3) cells via lactate dehydrogenase (LDH) assay, acridine orange staining and JC-1 probe, respectively. The physical interaction with model membranes was dominated by electrostatic forces, and the adhered GNSs disrupted the membrane. The degree of physical membrane disruption was quantified by the quartz crystal microbalance with dissipation (QCM-D), confirming the serious membrane disruption. The internalized GNSs were mainly distributed in the lysosomes. They caused plasma membrane leakage, increased the lysosomal membrane permeability (LMP), and depolarized the mitochondrial membrane potential (MMP). The increased cellular levels of reactive oxygen species (ROS) were also detected after GNS exposure. The combination of physical interaction and the excess ROS production damaged the plasma and organelle membranes in living RBL-2H3 cells. The lysosomal and mitochondrial dysfunction, and the oxidative stress further induced cell apoptosis. Specially, the exposure to 25 mg/L GNSs caused severest cell mortality, plasma membrane damage, ROS generation, MMP depolarization and apoptosis. The research findings provide more comprehensive information on the graphene-induced plasma and organelle membrane damage, which is important to understand and predict the cytotoxicity of carbon-based nanomaterials.

Graphene Hybrid Materials for Controlling Cellular Microenvironments

Cellular microenvironments are known as key factors controlling various cell functions, including adhesion, growth, migration, differentiation, and apoptosis. Many materials, including proteins, polymers, and metal hybrid composites, are reportedly effective in regulating cellular microenvironments, mostly via reshaping and manipulating cell morphologies, which ultimately affect cytoskeletal dynamics and related genetic behaviors. Recently, graphene and its derivatives have emerged as promising materials in biomedical research owing to their biocompatible properties as well as unique physicochemical characteristics. In this review, we will highlight and discuss recent studies reporting the regulation of the cellular microenvironment, with particular focus on the use of graphene derivatives or graphene hybrid materials to effectively control stem cell differentiation and cancer cell functions and behaviors. We hope that this review will accelerate research on the use of graphene derivatives to regulate various cellular microenvironments, which will ultimately be useful for both cancer therapy and stem cell-based regenerative medicine.

The Toxicity of Secondary Lithium-Sulfur Batteries Components

Currently, apart from the widely known lithium-ion batteries, there are competitive solutions in the form of, for example, Li-S batteries. While the results of studies on the toxicity of Li-ion battery components are published, such studies on the components of Li-S cells are just beginning. The purpose of the current review was to identify materials used in the production of Li-S batteries and their toxicity, especially for humans. The review showed many kinds of materials with different levels of toxicity utilized for manufacturing of these cells. Some materials are of low toxicity, while some others are of the high one. A lot of materials have assigned different hazard statements. For some of the materials, no hazard statements were assigned, although such materials are toxic. No data related to the toxicity of some materials were found in the literature. This points out the need to further studies on their toxicity and legal actions to assign appropriate hazard statements.

Comparative Effects of Graphene and Molybdenum Disulfide on Human Macrophage Toxicity

Graphene and other 2D materials, such as molybdenum disulfide, have been increasingly used in electronics, composites, and biomedicine. In particular, MoS₂ and graphene hybrids have attracted a great interest for applications in the biomedical research, therefore stimulating a pertinent investigation on their safety in immune cells like macrophages, which commonly engulf these materials. In this study, M1 and M2 macrophage viability and activation are mainly found to be unaffected by few-layer graphene (FLG) and MoS₂ at doses up to 50 µg mL^-1 . The uptake of both materials is confirmed by transmission electron microscopy, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. Notably, both 2D materials increase the secretion of inflammatory cytokines in M1 macrophages. At the highest dose, FLG decreases CD206 expression while MoS₂ decreases CD80 expression. CathB and CathL gene expressions are dose-dependently increased by both materials. Despite a minimal impact on the autophagic pathway, FLG is found to increase the expression of Atg5 and autophagic flux, as observed by Western blotting of LC3-II, in M1 macrophages. Overall, FLG and MoS₂ are of little toxicity in human macrophages even though they are found to trigger cell stress and inflammatory responses.

Nanoscale Assembly of 2D Materials for Energy and Environmental Applications

Rational design of 2D materials is crucial for the realization of their profound implications in energy and environmental fields. The past decade has witnessed significant developments in 2D material research, yet a number of critical challenges remain for real-world applications. Nanoscale assembly, precise control over the orientational and positional ordering, and complex interfaces among 2D layers are essential for the continued progress of 2D materials, especially for energy storage and conversion and environmental remediation. Herein, recent progress, the status, future prospects, and challenges associated with nanoscopic assembly of 2D materials are highlighted, specifically targeting energy and environmental applications. Geometric dimensional diversity of 2D material assembly is focused on, based on novel assembly mechanisms, including 1D fibers from the colloidal liquid crystalline phase, 2D films by interfacial tension (Marangoni effect), and 3D nanoarchitecture assembly by electrochemical processes. Relevant critical advantages of 2D material assembly are highlighted for application fields, including secondary batteries, supercapacitors, catalysts, gas sensors, desalination, and water decontamination.

Foliar graphene oxide treatment increases photosynthetic capacity and reduces oxidative stress in cadmium-stressed lettuce

The application of graphene oxide (GO) in the environment can have a positive or negative effect on the toxicity of pollutants, but the effect of GO on cadmium (Cd2+)-stressed lettuce has not yet been thoroughly studied. Therefore, we assessed the potential effects of foliar GO sprays on photosynthesis and antioxidant systems in Cd-stressed lettuce. We found that the foliar application of 30 mg L-1 of GO could significantly reduce signs of Cd2+ toxicity in lettuce. We observed increased net photosynthetic rates, stomatal conductance, transpiration rates, chlorophyll content, primary maximum photochemical efficiency of photosystem II, actual quantum yield, photosynthetic electron transport rates, ribulose-1,5-bisphosphate carboxylase and oxygenase concentrations, and biomass in Cd2+-stressed lettuce treated with GO. In addition, the foliar application of 30 mg L-1 of GO reduced the accumulation of the reactive oxygen species O·̄2 and H2O2, malondialdehyde content, and the activity of antioxidant enzymes. The decreased antioxidant enzyme activity could have been due to the decrease in reactive oxygen species. Cd2+ pollution is highly destructive to agricultural products, and the foliar application of GO provides a new potential tactic to improve the tolerance of plants to heavy metals.

A review on advances in graphene-derivative/polysaccharide bionanocomposites: Therapeutics, pharmacogenomics and toxicity

Graphene-based bionanocomposites are employed in several ailments, such as cancers and infectious diseases, due to their large surface area (to carry drugs), photothermal properties, and ease of their functionalization (owing to their active groups). Modification of graphene-derivatives with polysaccharides is a promising strategy to decrease their toxicity and improve target ability, which consequently enhances their biotherapeutic efficacy. Herein, functionalization of graphene-based materials with carbohydrate polymers (e.g., chitosan, starch, alginate, hyaluronic acid, and cellulose) are presented. Subsequently, recent advances in graphene nanomaterial/polysaccharide-based bionanocomposites in infection treatment and cancer therapy are comprehensively discussed. Pharmacogenomic and toxicity assessments for these bionanocomposites are also highlighted to provide insight for future optimized and smart investigations and researches.

Cytotoxicity and Immune Dysfunction of Dendritic Cells Caused by Graphene Oxide

Graphene, known as “black gold”, has important applications in various fields. In previous studies, it has been proved that graphene oxide (GO) which is a derivative of graphene has low toxicity. However, the immunotoxicity of GO has not been fully elucidated. In this work, we used DC2.4 cell line to investigate the in vitro immunotoxicity of two types of GO, mono-layer GO (mono-GO) and multi-layer GO (multi- GO). We found that mono-GO had less effect on cell viability than multi-GO, but both mono-GO and multi-GO significantly induced the generation of ROS in DC2.4 cells. Interestingly, mono-GO caused DC2.4 cells to aggregate, thus changed the cell morphology significantly. However, no similar influence occurred for multi-GO. In addition, the results showed that these two GOs obviously enhance the release of TNF-α by DC2.4 cells with and without LPS stimulation. GO did not affect the level of IL-6 released from DC2.4 cells, but multi-GO promoted the release of IL-6 while mono-GO inhibited the production of IL-6 when cells were in response to LPS stimulation. Whole-transcriptome sequencing analysis found some immune-related differentially expressed genes including H2-DMb1, Ncbp3, Oas2, Men1, Fas, Cd320, Cd244, and Tinagl1 which are engaged in the immune system process. These results suggested that both mono-GO and multi-GO are immunotoxic to DC2.4 cells, which provides important basis for subsequent biological and clinical medical applications.

Commonalities and Differences in the Transcriptional Response of the Model Fungus Saccharomyces cerevisiae to Different Commercial Graphene Oxide Materials

Graphene oxide has become a very appealing nanomaterial during the last years for many different applications, but its possible impact in different biological systems remains unclear. Here, an assessment to understand the toxicity of different commercial graphene oxide nanomaterials on the unicellular fungal model organism Saccharomyces cerevisiae was performed. For this task, an RNA purification protocol was optimized to avoid the high nucleic acid absorption capacity of graphene oxide. The developed protocol is based on a sorbitol gradient separation process for the isolation of adequate ribonucleic acid levels (in concentration and purity) from yeast cultures exposed to the carbon derived nanomaterial. To pinpoint potential toxicity mechanisms and pathways, the transcriptome of S. cerevisiae exposed to 160 mg L-1 of monolayer graphene oxide (GO) and graphene oxide nanocolloids (GOC) was studied and compared. Both graphene oxide products induced expression changes in a common group of genes (104), many of them related to iron homeostasis, starvation and stress response, amino acid metabolism and formate catabolism. Also, a high number of genes were only differentially expressed in either GO (236) or GOC (1077) exposures, indicating that different commercial products can induce specific changes in the physiological state of the fungus.

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.

Electroresponsive Silk-Based Biohybrid Composites for Electrochemically Controlled Growth Factor Delivery

Stimuli-responsive materials are very attractive candidates for on-demand drug delivery applications. Precise control over therapeutic agents in a local area is particularly enticing to regulate the biological repair process and promote tissue regeneration. Macromolecular therapeutics are difficult to embed for delivery, and achieving controlled release over long-term periods, which is required for tissue repair and regeneration, is challenging. Biohybrid composites incorporating natural biopolymers and electroconductive/active moieties are emerging as functional materials to be used as coatings, implants or scaffolds in regenerative medicine. Here, we report the development of electroresponsive biohybrid composites based on Bombyx mori silkworm fibroin and reduced graphene oxide that are electrostatically loaded with a high-molecular-weight therapeutic (i.e., 26 kDa nerve growth factor-β (NGF-β)). NGF-β-loaded composite films were shown to control the release of the drug over a 10-day period in a pulsatile fashion upon the on/off application of an electrical stimulus. The results shown here pave the way for personalized and biologically responsive scaffolds, coatings and implantable devices to be used in neural tissue engineering applications, and could be translated to other electrically sensitive tissues as well.

Effect of Graphene Family Materials on Multiple Myeloma and Non-Hodgkin's Lymphoma Cell Lines

The interest around the graphene family of materials is constantly growing due to their potential application in biomedical fields. The effect of graphene and its derivatives on cells varies amongst studies depending on the cell and tissue type. Since the toxicity against non-adherent cell lines has barely been studied, we investigated the effect of graphene and two different graphene oxides against four multiple myeloma cell lines, namely KMS-12-BM, H929, U226, and MM.1S, as well as two non-Hodgkin lymphoma cells lines, namely KARPAS299 and DOHH-2. We performed two types of viability assays, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide conversion) and ATP (adenosine triphosphate detection), flow cytometry analysis of apoptosis induction and cell cycle, cell morphology, and direct interaction analysis using two approaches-visualization of living cells by two different systems, and visualization of fixed and dyed cells. Our results revealed that graphene and graphene oxides exhibit low to moderate cytotoxicity against cells, despite visible interaction between the cells and graphene oxide. This creates possibilities for the application of the selected graphene materials for drug delivery systems or theragnostics in hematological malignancies; however, further detailed studies are necessary to explain the nature of interactions between the cells and the materials.

Workers' Exposure Assessment during the Production of Graphene Nanoplatelets in R&D Laboratory

Widespread production and use of engineered nanomaterials in industrial and research settings raise concerns about their health impact in the workplace. In the last years, graphene-based nanomaterials have gained particular interest in many application fields. Among them, graphene nanoplatelets (GNPs) showed superior electrical, optical and thermal properties, low-cost and availability. Few and conflicting results have been reported about toxicity and potential effects on workers’ health, during the production and handling of these nanostructures. Due to this lack of knowledge, systematic approaches are needed to assess risks and quantify workers’ exposure to GNPs. This work applies a multi-metric approach to assess workers’ exposure during the production of GNPs, based on the Organization for Economic Cooperation and Development (OECD) methodology by integrating real-time measurements and personal sampling. In particular, we analyzed the particle number concentration, the average diameter and the lung deposited surface area of airborne nanoparticles during the production process conducted by thermal exfoliation in two different ways, compared to the background. These results have been integrated by electron microscopic and spectroscopic analysis on the filters sampled by personal impactors. The study identifies the process phases potentially at risk for workers and reports quantitative information about the parameters that may influence the exposure in order to propose recommendations for a safer design of GNPs production process.

Graphene oxide size-dependently altered lipid profiles in THP-1 macrophages

Previous studies focused on biocompatibility of graphene oxide (GO) to macrophages, but the impact of GO on lipid profiles in macrophages was less investigated. Herein, we investigated the interactions between THP-1 macrophages and GO of different sizes (GO of size 500-5000 nm, denoted as GO-L; GO of size < 500 nm, denoted as GO-S). We found that after 24 h exposure, the internalization of GO appeared to be minimal, whereas up to 50 μg/mL of GO-L but not GO-S reduced lipid accumulation, accompanying with a significantly reduced release of soluble monocyte chemoattractant protein-1 (MCP-1) but not interleukin-6 (IL-6). Moreover, lipidomic data showed that GO-L decreased the levels of 17 lipid classes, whereas GO-S only decreased the levels of 5 lipid classes. For comparison, 50 μg/mL carbon black (CB) significantly increased lipid accumulation with considerable particle internalization. GO-reduced lipid accumulation was not related with increase of reactive oxygen species (ROS) or induction of autophagy, and modulation of autophagy by chemicals showed no significant effect to alter the effects of GO-L on lipid accumulation. However, exposure to GO reduced the mRNA and protein levels of key components in peroxisome proliferators-activated receptor (PPAR) signaling pathway, a pathway that is related with lipid droplet biogenesis, and the modulation of PPARγ by chemicals altered the effects of GO-L on lipid accumulation. In conclusion, our results suggested that GO size-dependently altered lipid profiles in THP-1 macrophages that might be related with PPAR signaling pathway.

Induction of ferroptosis in response to graphene quantum dots through mitochondrial oxidative stress in microglia

BACKGROUND

Graphene quantum dots (GQDs) provide a bright prospect in the biomedical application because they contain low-toxic compounds and promise imaging of deep tissues and tiny vascular structures. However, the biosafety of this novel QDs has not been thoroughly evaluated, especially in the central nervous system (CNS). The microarray analysis provides a hint that nitrogen-doped GQDs (N-GQDs) exposure could cause ferroptosis in microglia, which is a novel form of cell death dependent on iron overload and lipid peroxidation.

RESULTS

The cytosolic iron overload, glutathione (GSH) depletion, excessive reactive oxygen species (ROS) production and lipid peroxidation (LPO) were observed in microglial BV2 cells treated with N-GQDs, which indicated that N-GQDs could damage the iron metabolism and redox balance in microglia. The pre-treatments of a specific ferroptosis inhibitor Ferrostatin-1 (Fer-1) and an iron chelater Deferoxamine mesylate (DFO) not only inhibited cell death, but also alleviated iron overload, LPO and alternations in ferroptosis biomarkers in microglia, which were caused by N-GQDs. When assessing the potential mechanisms of N-GQDs causing ferroptosis in microglia, we found that the iron content, ROS generation and LPO level in mitochondria of BV2 cells all enhanced after N-GQDs exposure. When the antioxidant ability of mitochondria was increased by the pre-treatment of a mitochondria targeted ROS scavenger MitoTEMPO, the ferroptotic biological changes were effectively reversed in BV2 cells treated with N-GQDs, which indicated that the N-GQDs-induced ferroptosis in microglia could be attributed to the mitochondrial oxidative stress. Additionally, amino functionalized GQDs (A-GQDs) elicited milder redox imbalance in mitochondria and resulted in less ferroptotic effects than N-GQDs in microglia, which suggested a slight protection of amino group functionalization in GQDs causing ferroptosis.

CONCLUSION

N-GQDs exposure caused ferroptosis in microglia via inducing mitochondrial oxidative stress, and the ferroptotic effects induced by A-GQDs were milder than N-GQDs when the exposure method is same. This study will not only provide new insights in the GQDs-induced cell damage performed in multiple types of cell death, but also in the influence of chemical modification on the toxicity of GQDs.

Graphene oxide as a potential drug carrier - Chemical carrier activation, drug attachment and its enzymatic controlled release

Graphene oxide (GO), due to its properties, such as nanometric dimensions, large specific surface area, and biocompatibility, can be used as a carrier in controlled drug release systems. The method of its chemical activation before drug molecules binding was elaborated. Doxorubicin (DOX), an anticancer drug, was attached to the surface of GO via the Gly-Gly-Leu linker. Approximately 3.07 · 10²⁰ molecules of the tripeptide were attached to 1 g of GO and subsequently almost the same number of DOX molecules. GO was suspended inside a sol surrounded by a thin porous membrane. The bound DOX was effectively released using thermolysin, an enzyme cleaving peptide bonds between Gly and Leu inside the linker structure. The membrane, as the shell was responsible for keeping enzyme molecules in their native form and GO flakes inside the carrier, simultaneously allowed the released drug molecules to diffuse outside. The rate of drug release was described as a function of the enzyme concentration and mass of DOX expressed on carrier volume; thus, the daily dose and length of the therapy can be controlled. Studies involving the cell line of mice fibrosarcoma WEHI 164 have shown that the prepared carrier itself is not toxic and only the introduction of DOX-releasing enzyme into it causes cell death.

Applications of Graphene and Its Derivatives in the Upstream Oil and Gas Industry: A Systematic Review

Graphene and its derivatives, with their unique two-dimensional structures and excellent physical and chemical properties, have been an international research hotspot both in the research community and industry. However, in application-oriented research in the oil and gas industry they have only drawn attention in the past several years. Their excellent optical, electrical, thermal and mechanical performance make them great candidates for use in oil and gas exploration, drilling, production, and transportation. Combined with the actual requirements for well working fluids, chemical enhanced oil recovery, heavy oil recovery, profile control and water shutoff, tracers, oily wastewater treatment, pipeline corrosion prevention treatment, and tools and apparatus, etc., this paper introduces the behavior in water and toxicity to organisms of graphene and its derivatives in detail, and comprehensively reviews the research progress of graphene materials in the upstream oil and gas industry. Based on this, suggestions were put forward for the future research. This work is useful to the in-depth mechanism research and application scope broadening research in the upstream oil and gas industry.

Release of graphene-related materials from epoxy-based composites: characterization, quantification and hazard assessment in vitro

Due to their mechanical strength, thermal stability and electrical conductivity, graphene-related materials (GRMs) have been extensively explored for various applications. Moreover, GRMs have been studied and applied as fillers in polymer composite manufacturing to enhance the polymer performance. With the foreseen growth in GRM production, occupational and consumer exposure is inevitable, thus raising concerns for potential health risks. Therefore, this study aims (1) to characterize aerosol particles released after mechanical abrasion on GRM-reinforced epoxy composites, (2) to quantify the amounts of protruding and free-standing GRMs in the abraded particles and (3) to assess the potential effects of the pristine GRMs as well as the abraded particles on human macrophages differentiated from the THP-1 cell line in vitro. GRMs used in this study included graphene nanoplatelets (GNPs), graphene oxide (GO), and reduced graphene oxide (rGO). All types of pristine GRMs tested induced a dose-dependent increase in reactive oxygen species formation, but a decrease in cell viability was only detected for large GNPs at high concentrations (20 and 40 μg mL^-1). The particle modes measured using a scanning mobility particle sizer (SMPS) were 300-400 nm and using an aerodynamic particle sizer (APS) were between 2-3 μm, indicating the release of respirable particles. A significant fraction (51% to 92%) of the GRMs embedded in the epoxy composites was released in the form of free-standing or protruding GRMs in the abraded particles. The abraded particles did not induce any acute cytotoxic effects.

Assessing the Influence of the Sourcing Voltage on Polyaniline Composites for Stress Sensing Applications

Polyaniline (PANI) has recently gained great attention due to its outstanding electrical properties and ease of processability; these characteristics make it ideal for the manufacturing of polymer blends. In this study, the processing and piezoresistive characterization of polymer composites resulting from the blend of PANI with ultra-high molecular weight polyethylene (UHMWPE) in different weight percentages (wt %) is reported. The PANI/UHMWPE composites were uniformly homogenized by mechanical mixing and the pellets were manufactured by compression molding. A total of four pellets were manufactured, with PANI percentages of 20, 25, 30 and 35 wt %. Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the effective distribution of PANI and UHMWPE particles in the pellets. A piezoresistive characterization was performed on the basis of compressive forces at different voltages; it was found that the error metrics of hysteresis and drift were influenced by the operating voltage. In general, larger voltages lowered the error metrics, but a reduction in sensor sensitivity came along with voltage increments. In an attempt to explain such a phenomenon, the authors developed a microscopic model for the piezoresistive response of PANI composites, aiming towards a broader usage of PANI composites in strain/stress sensing applications as an alternative to carbonaceous materials.

Antibacterial Action of Nanoparticle Loaded Nanocomposites Based on Graphene and Its Derivatives: A Mini-Review

Bacterial infections constitute a severe problem in various areas of everyday life, causing pain and death, and adding enormous costs to healthcare worldwide. Besides, they cause important concerns in other industries, such as cloth, food packaging, and biomedicine, among others. Despite the intensive efforts of academics and researchers, there is lack of a general solutions to restrict bacterial growth. Among the various approaches, the use of antibacterial nanomaterials is a very promising way to fight the microorganisms due to their high specific surface area and intrinsic or chemically incorporated antibacterial action. Graphene, a 2D carbon-based ultra-thin biocompatible nanomaterial with excellent mechanical, thermal, and electrical properties, and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), are highly suitable candidates for restricting microbial infections. However, the mechanisms of antimicrobial action, their cytotoxicity, and other issues remain unclear. This mini-review provides select examples on the leading advances in the development of antimicrobial nanocomposites incorporating inorganic nanoparticles and graphene or its derivatives, with the aim of providing a better understanding of the antibacterial properties of graphene-based nanomaterials.

Graphene oxide nanofilm and the addition of L-glutamine can promote development of embryonic muscle cells

Background

Formation of muscular pseudo-tissue depends on muscle precursor cells, the extracellular matrix (ECM)-mimicking structure and factors stimulating cell differentiation. These three things cooperate and can create a tissue-like structure, however, their interrelationships are relatively unknown. The objective was to study the interaction between surface properties, culture medium composition and heterogeneous cell culture. We would like to demonstrate that changing the surface properties by coating with graphene oxide nanofilm (nGO) can affect cell behaviour and especially their need for the key amino acid l-glutamine (L-Glu).

Results

Chicken embryo muscle cells and their precursors, cultured in vitro, were used as the experimental model. The mesenchymal stem cell, collected from the hind limb of the chicken embryo at day 8 were divided into 4 groups; the control group and groups treated with nGO, L-Glu and nGO supplied with L-Glu (nGOxL-Glu). The roughness of the surface of the plastic plate covered with nGO was much lower than a standard plate. The test of nGO biocompatibility demonstrated that the cells were willing to settle on the nGO without any toxic effects. Moreover, nGO by increasing hydrophilicity and reducing roughness and presumably through chemical bonds available on the GO surface stimulated the colonisation of primary stromal cells that promote embryonic satellite cells. The viability significantly increased in cells cultured on nGOxL-Glu. Observations of cell morphology showed that the most mature state of myogenesis was characteristic for the group nGOxL-Glu. This result was confirmed by increasing the expression of MYF5 genes at mRNA and protein levels. nGO also increased the expression of MYF5 and also very strongly the expression of PAX7 at mRNA and protein levels. However, when analysing the expression of PAX7, a positive link was observed between the nGO surface and the addition of L-Glu.

Conclusions

The use of nGO and L-Glu supplement may improve myogenesis and also the myogenic potential of myocytes and their precursors by promoting the formation of satellite cells. Studies have, for the first time, demonstrated positive cooperation between surface properties nGO and L-Glu supplementation to the culture medium regarding the myogenic potential of cells involved in muscle formation.