Minimizing oxidation and stable nanoscale dispersion improves the biocompatibility of graphene in the lung

Modulation of protein-graphene oxide interactions with varying degrees of oxidation

The degree of oxidation of graphene oxide (GO) has been shown to be important for its toxicity and drug-loading efficiency. However, the effect of its variations on GO-protein interaction remains unclear. Here, we evaluate the effect of the different oxidation degrees of GO on its interaction with human ubiquitin (8.6 kDa) using solution state nuclear magnetic resonance (NMR) spectroscopy in combination with other biophysical techniques. Our findings show that the interaction between the protein and the different GO samples is weak and electrostatic in nature. It involves fast dynamic exchange of the protein molecules from the surface of the GO. As the oxidation degree of the GO increases, the extent of the interaction with the protein changes. The interaction of the protein with GO can thus be modulated by tuning the degree of oxidation. This study opens up new avenues to design appropriate graphenic materials for use in various biomedical fields such as drug delivery, biomedical devices and imaging.

On Facing the SARS-CoV-2 (COVID-19) with Combination of Nanomaterials and Medicine: Possible Strategies and First Challenges

Global health is facing the most dangerous situation regarding the novel severe acute respiratory syndrome called coronavirus 2 (SARS-CoV-2), which is widely known as the abbreviated COVID-19 pandemic. This is due to the highly infectious nature of the disease and its possibility to cause pneumonia induced death in approximately 6.89% of infected individuals (data until 27 April 2020). The pathogen causing COVID-19 is called severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which is believed to be originated from the Wuhan Province in China. Unfortunately, an effective and approved vaccine for SARS-CoV-2 virus is still not available, making the situation more dangerous and currently available medical care futile. This unmet medical need thus requires significant and very urgent research attention to develop an effective vaccine to address the SARS-CoV-2 virus. In this review, the state-of-the-art drug design strategies against the virus are critically summarized including exploitations of novel drugs and potentials of repurposed drugs. The applications of nanochemistry and general nanotechnology was also discussed to give the status of nanodiagnostic systems for COVID-19.

2D Nanomaterials for Cancer Theranostic Applications

2D nanomaterials with unique nanosheet structures, large surface areas, and extraordinary physicochemical properties have attracted tremendous interest. In the area of nanomedicine, research on graphene and its derivatives for diverse biomedical applications began as early as 2008. Since then, many other types of 2D nanomaterials, including transition metal dichalcogenides, transition metal carbides, nitrides and carbonitrides, black phosphorus nanosheets, layered double hydroxides, and metal-organic framework nanosheets, have been explored in the area of nanomedicine over the past decade. In particular, a large surface area makes 2D nanomaterials highly efficient drug delivery nanoplatforms. The unique optical and/or X-ray attenuation properties of 2D nanomaterials can be harnessed for phototherapy or radiotherapy of cancer. Furthermore, by integrating 2D nanomaterials with other functional nanoparticles or utilizing their inherent physical properties, 2D nanomaterials may also be engineered as nanoprobes for multimodal imaging of tumors. 2D nanomaterials have shown substantial potential for cancer theranostics. Herein, the latest progress in the development of 2D nanomaterials for cancer theranostic applications is summarized. Current challenges and future perspectives of 2D nanomaterials applied in nanomedicine are also discussed.

Graphene Oxide Nanosheets for Localized Hyperthermia-Physicochemical Characterization, Biocompatibility, and Induction of Tumor Cell Death

BACKGROUND

The main goals of cancer treatment are not only to eradicate the tumor itself but also to elicit a specific immune response that overcomes the resistance of tumor cells against chemo- and radiotherapies. Hyperthermia was demonstrated to chemo- and radio-sensitize cancerous cells. Many reports have confirmed the immunostimulatory effect of such multi-modal routines.

METHODS

We evaluated the interaction of graphene oxide (GO) nanosheets; its derivatives reduced GO and PEGylated rGO, with components of peripheral blood and evaluated its thermal conductivity to induce cell death by localized hyperthermia.

RESULTS

We confirmed the sterility and biocompatibility of the graphene nanomaterials and demonstrated that hyperthermia applied alone or in the combination with radiotherapy induced much more cell death in tumor cells than irradiation alone. Cell death was confirmed by the release of lactate dehydrogenase from dead and dying tumor cells.

CONCLUSION

Biocompatible GO and its derivatives can be successfully used in graphene-induced hyperthermia to elicit tumor cell death.

The interrupted effect of autophagic flux and lysosomal function induced by graphene oxide in p62-dependent apoptosis of F98 cells

BACKGROUND

Graphene oxide (GO) nanoparticles (NPs) have been widely applied in various fields, especially in biomedical applications. Extensive studies have suggested that GO can pass through the blood-brain barrier (BBB) and induce abnormal autophagy and cytotoxicity in the central nervous system (CNS). However, the effect and specific mechanism of GO on astrocytes, the most abundant cells in the brain still has not been extensively investigated.

RESULTS

In this study, we systematically explored the toxicity and mechanism of GO exposure in the rat astroglioma-derived F98 cell line using molecular biological techniques (immunofluorescence staining, flow cytometry and Western blot) at the subcellular level and the signaling pathway level. Cells exposed to GO exhibited decreased cell viability and increased lactate dehydrogenase (LDH) release in a concentration- and time-dependent manner. GO-induced autophagy was evidenced by transmission electron microscopy (TEM) and immunofluorescence staining. Western blots showed that LC3II/I and p62 were upregulated and PI3K/Akt/mTOR was downregulated. Detection of lysosomal acidity and cathepsin B activity assay indicated the impairment of lysosomal function. Annexin V-FITC-PI detection showed the occurrence of apoptosis after GO exposure. The decrease in mitochondrial membrane potential (MMP) with an accompanying upregulation of cleaved caspase-3 and Bax/Bcl-2 further suggested that endogenous signaling pathways were involved in GO-induced apoptosis.

CONCLUSION

The exposure of F98 cells to GO can elicit concentration- and time-dependent toxicological effects. Additionally, increased autophagic response can be triggered after GO treatment and that the blocking of autophagy flux plays a vital role in GO cytotoxicity, which was determined to be related to dysfunction of lysosomal degradation. Importantly, the abnormal accumulation of autophagic substrate p62 protein can induce capase-3-mediated apoptosis. Inhibition of abnormal accumulation of autophagic cargo could alleviate the occurrence of GO-induced apoptosis in F98 cells.

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.

PEGylated nano-graphene oxide as a nanocarrier for delivering mixed anticancer drugs to improve anticancer activity

Due to their high specific surface area, graphene oxide and graphene oxide-base nanoparticles have great potential both in dual-drug delivery and combination chemotherapy. Herein, we developed cisplatin (Pt) and doxorubicin (DOX) dual-drug-loaded PEGylated nano-graphene oxide (pGO) to facilitate combined chemotherapy in one system. In this study, nano-sized pGO-Pt/DOX ranged around 161.50 nm was fabricated and characterized using zeta-potential, AFM, TEM, Raman, UV-Vis, and FTIR analyses. The drug delivery efficacy of Pt was enhanced through the introduction of pGO, and the final weight ratio of DOX: Pt: pGO was optimized to 0.376: 0.376: 1. In vitro studies revealed that pGO-Pt/DOX nanoparticles could be effectively delivered into tumor cells, in which they induced prominent cell apoptosis and necrosis and exhibited higher growth inhibition than the single drug delivery system or free drugs. The pGO-Pt/DOX induced the most prominent cancer cell apoptosis and necrosis rate with 18.6%, which was observed almost 2 times higher than that of pGO-Pt or pGO-DOX groups. in the apoptosis and necrotic quadrants In vivo data confirmed that the pGO-Pt/DOX dual-drug delivery system attenuated the toxicity of Pt and DOX to normal organs compared to free drugs. The tumor inhibition data, histopathology observations, and immunohistochemical staining confirmed that the dual-drug delivery system presented a better anticancer effect than free drugs. These results clearly indicated that the pGO-Pt/DOX dual-drug delivery system provided the means for combination drug delivery in cancer treatment.

Current outlook on radionuclide delivery systems: from design consideration to translation into clinics

Radiopharmaceuticals have proven to be effective agents, since they can be successfully applied for both diagnostics and therapy. Effective application of relevant radionuclides in pre-clinical and clinical studies depends on the choice of a sufficient delivery platform. Herein, we provide a comprehensive review on the most relevant aspects in radionuclide delivery using the most employed carrier systems, including, (i) monoclonal antibodies and their fragments, (ii) organic and (iii) inorganic nanoparticles, and (iv) microspheres. This review offers an extensive analysis of radionuclide delivery systems, the approaches of their modification and radiolabeling strategies with the further prospects of their implementation in multimodal imaging and disease curing. Finally, the comparative outlook on the carriers and radionuclide choice, as well as on the targeting efficiency of the developed systems is discussed.

Exposure to graphene nanoparticles induces changes in measures of vascular/renal function in a load and form-dependent manner in mice

Graphenes isolated from crystalline graphite are used in several industries. Employees working in the production of graphenes may be at risk of developing respiratory problems attributed to inhalation or contact with particulate matter (PM). However, graphene nanoparticles might also enter the circulation and accumulate in other organs. The aim of this study was to examine how different forms of graphene affect peripheral vascular functions, generation of reactive oxygen species (ROS) and changes in gene expression that may be indicative of cardiovascular and/or renal dysfunction. In the first investigation, different doses of graphene nanoplatelets were administered to mice via oropharyngeal aspiration. These effects were compared to those of dispersion medium (DM) and carbon black (CB). Gene expression alterations were observed in the heart for CB and graphene; however, only CB produced changes in peripheral vascular function. In the second study, oxidized forms of graphene were administered. Both oxidized forms increased the sensitivity of peripheral blood vessels to adrenoreceptor-mediated vasoconstriction and induced changes in ROS levels in the heart. Based upon the results of these investigations, exposure to graphene nanoparticles produced physiological and alterations in ROS and gene expression that may lead to cardiovascular dysfunction. Evidence indicates that the effects of these particles may be dependent upon dose and graphene form to which an individual may be exposed to.

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.

Two dimensional carbon based nanocomposites as multimodal therapeutic and diagnostic platform: A biomedical and toxicological perspective

Graphene based nanocomposites have revolutionized cancer treatment, diagnosis and imaging owing to its good compatibility, elegant flexibility, high surface area, low mass density along with excellent combined additive effect of graphene with other nanomaterials. This review inculcates the type of graphene based nanocomposites and their fabrication techniques to improve its properties as photothermal and theranostic platform. With decades' efforts, many significant breakthroughs in the method of synthesis and characterization in addition to various functionalization options of graphene based nanocomposite have paved a solid foundation for their potential applications in the cancer therapy. This work intends to provide a thorough, up-to-date holistic discussion on correlation of breakthroughs with their biomedical applications and illustrate how to utilize these breakthroughs to address long-standing challenges in the clinical translation of nanomedicines. This review also emphasizes on graphene based nanocomposites based toxicity concerns pertaining to delivery platforms.

Recent advances in graphene-based nanomaterials: properties, toxicity and applications in chemistry, biology and medicine

This review (with 239 refs.) summarizes the progress that has been made in applications of graphene-based nanomaterials (such as plain graphene, graphene oxides, doped graphene oxides, graphene quantums dots) in biosensing, imaging, drug delivery and diagnosis. Following an introduction into the field, a first large section covers the toxicity of graphene and its derivatives (with subsections on bacterial toxicity and tissue toxicity). The use of graphene-based nanomaterials in sensors is reviewed next, with subsections on electrochemical, FET-based, fluorescent, chemiluminescent and colorimetric sensors and probes. The large field of imaging is treated next, with subchapters on optical, PET-based, and magnetic resonance based methods. A concluding section summarizes the current status, addresses current challenges, and gives an outlook on potential future trends. Graphical Abstract Schematic presentation of the potential applications of graphene-based materials in life science and biomedicine, emphatically reflected in some vital areas such as DNA analysis, biological monitoring, drug delivery, in vitro labelling, in vivo imaging, tumor target, etc.

Derivation of occupational exposure limits for multi-walled carbon nanotubes and graphene using subchronic inhalation toxicity data and a multi-path particle dosimetry model

In this study, we aimed to provide the recommended occupational exposure limits (OELs) for multi-walled carbon nanotubes (MWCNTs) and graphene nanomaterials based on data from a subchronic inhalation toxicity study using a lung dosimetry model. We used a no observed adverse effect level (NOAEL) of 0.98 mg m^-3 and 3.02 mg m^-3 in rats for MWCNTs and graphene, respectively. The NOAELs were obtained from a 13-week inhalation study in rats. The deposition fractions of MWCNTs and graphene in the respiratory tract of rats and humans were calculated by using the multi-path particle dosimetry model (MPPD model, v3.04). The deposition fraction in the alveolar region was 0.0527 and 0.0984 for MWCNTs and 0.0569 and 0.1043 for graphene in rats and human lungs, respectively. Then, the human equivalent exposure concentrations (HECs) of MWCNTs and graphene were calculated according to the method by the National Institute for Occupational Safety and Health (NIOSH). The HEC was estimated to be 0.17 mg m^-3 for MWCNTs and to be 0.54 mg m^-3 for graphene, which was relevant to the rat NOAEL of 0.98 mg m^-3 and 3.02 mg m^-3 for MWCNTs and graphene, respectively. Finally, we estimated the recommended OELs by applying uncertainty factors (UFs) to the HEC as follows: an UF of 3 for species differences (rats to humans), 2 for an experimental duration (subchronic to chronic), and 5 for inter-individual variations among workers. Thus, the OEL was estimated to be 6 μg m^-3 for MWCNTs and 18 μg m^-3 for graphene. These values could be useful in preventing the adverse health effects of nanoparticles in workers.

The role of macrophages in the resolution of inflammation

Macrophages are tissue-resident or infiltrated immune cells critical for innate immunity, normal tissue development, homeostasis, and repair of damaged tissue. Macrophage function is a sum of their ontogeny, the local environment in which they reside, and the type of injuries or pathogen to which they are exposed. In this Review, we discuss the role of macrophages in the restoration of tissue function after injury, highlighting important questions about how they respond to and modify the local microenvironment to restore homeostasis.

In vitro cardiotoxicity evaluation of graphene oxide

Graphene is a two-dimensional (2D) monolayer of carbon atoms, tightly packed, forming a honey comb crystal lattice, with physical, chemical, and mechanical properties greatly used for energy storage, electrochemical devices, and in nanomedicine. Many studies showed that nanomaterials have side-effects on health. At present, there is a lack of information regarding graphene and its derivatives including their cardiotoxic properties. The aim of the present study was to evaluate the toxicity of nano-graphene oxide (nano-GO) in the rat cardiomyoblast cell line H9c2 and the involvement of oxidative processes. The cell viability was evaluated with the fluorescein diacetate (FDA)/propidium iodide (PI) and in the trypan blue exclusion assay, furthermore mitochondrial membrane potential and production of free radicals were measured. Genotoxicity was evaluated in comet assay and low molecular weight DNA experiment. Reduction of cell viability with 20, 40, 60, 80, and 100 μg/mL nano-GO was observed after 24 h incubation. Besides, nano-GO induced a mitochondrial hyperpolarization and a significant increase of free radicals production in the same concentrations. DNA breaks were observed at 40, 60, 80, and 100 μg/mL. This DNA damage was accompanied by a significant increase in LMW DNA only at 40 μg/mL. In conclusion, the nano-GO caused cardiotoxicity in our in vitro model, with mitochondrial disturbances, generation of reactive species and interactions with DNA, indicating the importance of the further evaluation of the safety of nanomaterials.

Graphene oxide touches blood: in vivo interactions of bio-coronated 2D materials

Graphene oxide is the hot topic in biomedical and pharmaceutical research of the current decade. However, its complex interactions with human blood components complicate the transition from the promising in vitro results to clinical settings. Even though graphene oxide is made with the same atoms as our organs, tissues and cells, its bi-dimensional nature causes unique interactions with blood proteins and biological membranes and can lead to severe effects like thrombogenicity and immune cell activation. In this review, we will describe the journey of graphene oxide after injection into the bloodstream, from the initial interactions with plasma proteins to the formation of the "biomolecular corona", and biodistribution. We will consider the link between the chemical properties of graphene oxide (and its functionalized/reduced derivatives), protein binding and in vivo response. We will also summarize data on biodistribution and toxicity in view of the current knowledge of the influence of the biomolecular corona on these processes. Our aim is to shed light on the unsolved problems regarding the graphene oxide corona to build the groundwork for the future development of drug delivery technology.

Preparation and evaluation of Bletilla striata polysaccharide/graphene oxide composite hemostatic sponge

Uncontrolled bleeding is an important cause of military and civilian casualties. GO has received more attention in the field of hemostasis. However, pure GO has various limitation in application due to its potential thrombosis, hemolytic and cytotoxicity. Herein, we present a simple, rapid and low-cost method to combine GO and natural polysaccharides by hydrogen bonding to prepare a new material Bletilla striata polysaccharide/graphene oxide composite sponge (BGCS). The BGCS was successfully synthesized and characterized by SEM, IR, RAMAN, XRD and Zeta potential analyzer analysis. The BGCS exhibited favorable biocompatibility. Besides, the porosity of BGCS was higher than 90% and showed good water absorption capacity. The results of whole blood coagulation evaluation showed that the BGCS can promote blood coagulation within 30 s without anticoagulant, showing excellent hemostatic effect. Further coagulation mechanism studies indicated that the surface of the BGCS possessed a high charge (-27.3 ± 0.9 mV) and showed strong platelet stimulation, the BGCS can also induce red blood cell aggregation, accelerate fibrin formation and accelerate blood coagulation. Therefore, the BGCS can stop bleeding within 50 s in rat-tail amputation models. The BGCS provides a new perspective for the safe application of GO in the field of trauma hemostasis.

Applications of graphene oxide in case of nanomedicines and nanocarriers for biomolecules: review study

In this Review article, recent progress in matter of graphene oxide (GO) synthesis and its functionalization via a vast range of materials, including small molecules, polymers, and biomolecules, were reported and systematically summarized in order to overcome the inherent drawbacks of GO nanocarriers and thereby make these nanocarriers suitable for delivering chemotherapeutic agents, genes, and short interfering RNAs. Briefly, this work describes current strategies for the large scale production of GO and modification of graphene-based nanocarriers surfaces through practical chemical approaches, improving their biocompatibility and declining their toxicity. It also describes the most relevant cases of study suitable to demonstrate the role of graphene and graphene derivatives (GD) as nanocarrier for anti-cancer drugs and genes (e.g. miRNAs). Moreover, the controlled release mechanisms within the cell compartments and blood pH for targeted therapeutics release in the acidic environment of tumor cells or in intracellular compartments are mentioned and explored.

Metformin Targets Mitochondrial Electron Transport to Reduce Air-Pollution-Induced Thrombosis

Urban particulate matter air pollution induces the release of pro-inflammatory cytokines including interleukin-6 (IL-6) from alveolar macrophages, resulting in an increase in thrombosis. Here, we report that metformin provides protection in this murine model. Treatment of mice with metformin or exposure of murine or human alveolar macrophages to metformin prevented the particulate matter-induced generation of complex III mitochondrial reactive oxygen species, which were necessary for the opening of calcium release-activated channels (CRAC) and release of IL-6. Targeted genetic deletion of electron transport or CRAC channels in alveolar macrophages in mice prevented particulate matter-induced acceleration of arterial thrombosis. These findings suggest metformin as a potential therapy to prevent some of the premature deaths attributable to air pollution exposure worldwide.

Modeling Interactions between Liposomes and Hydrophobic Nanosheets

2D nanomaterials could cause structural disruption and cytotoxic effects to cells, which greatly challenges their promising biomedical applications including biosensing, bioimaging, and drug delivery. Here, the physical and mechanical interaction between lipid liposomes and hydrophobic nanosheets is studied utilizing coarse-grained (CG) molecular dynamics (MD) simulations. The simulations reveal a variety of characteristic interaction morphologies that depend on the size and the orientation of nanosheets. Dynamic and thermodynamic analyses on the morphologic evolution provide insights into molecular motions such as "nanosheet rotation," "lipid extraction," "lipid flip-flop," and "lipid spreading." Driven by these molecular motions, hydrophobic nanosheets cause morphologic changes of liposomes. The lipid bilayer structure can be corrugated, and the overall liposome sphere can be split or collapsed by large nanosheets. In addition, nanosheets embedded into lipid bilayers greatly weaken the fluidity of lipids, and this effect can be cumulatively enhanced as nanosheets continuously intrude. These results could facilitate molecular-level understanding on the cytotoxicity of nanomaterials, and help future nanotoxicology studies associating computational modeling with experiments.

Femtomolar Detection of Lipopolysaccharide in Injectables and Serum Samples Using Aptamer-Coupled Reduced Graphene Oxide in a Continuous Injection-Electrostacking Biochip

A method for microfluidic sample preconcentration to detect femtomolar level of lipopolysaccharide (LPS) is introduced, enabled by 6-carboxyfluorescein (6-FAM) labeled aptamer-LPS binding along with reduced graphene oxide (rGO). The free FAM-aptamers can be adsorbed onto the surface of rGO, resulting in fluorescence quenching of background signals. Conversely, the aptamer-LPS complex cannot be adsorbed by rGO, so the fluorescence is maintained and detected. When an electric field is applied across the microchannel with Nafion membrane in the chip, only the fluorescence of aptamer-LPS complex can be detected and stacked by continuous injection-electrostacking (CI-ES). The method shows a high selectivity (in the presence of pyrophosphate, FAD⁺, NAD⁺, AMP, ADP, ATP, phosphatidylcholine, LTA, and β-d-glucans which respond positively to LAL) to LPS and an extreme sensitivity with the limit of detection (LOD) at 7.9 fM (7.9 × 10^-4 EU/mL) and 8.3 fM (8.3 × 10^-4 EU/mL) for water sample and serum sample, respectively. As a practical application, this method can detect LPS in injections and serum samples of human and sepsis model mouse and quickly distinguish Gram-negative bacteria Escherichia coli ( E. coli) from Gram-positive bacteria Staphylococcus aureus ( S. aureus) and fungus Candida albicans ( C. albicans). More importantly, by changing the aptamers based on different targets, we can detect different analytes. Therefore, aptamer-coupled rGO in a CI-ES biochip is a universal, sensitive, and specific method. For TOC only.

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.

Physically-triggered nanosystems based on two-dimensional materials for cancer theranostics

There is an increasing demand to develop effective methods for treating malignant diseases to improve healthcare in our society. Stimuli-responsive nanosystems, which can respond to internal or external stimuli are promising in cancer therapy and diagnosis due to their functionality and versatility. As a newly emerging class of nanomaterials, two-dimensional (2D) nanomaterials have attracted huge interest in many different fields including biomedicine due to their unique physical and chemical properties. In the past decade, stimuli-responsive nanosystems based on 2D nanomaterials have been widely studied, showing promising applications in cancer therapy and diagnosis, including phototherapies, magnetic therapy, drug and gene delivery, and non-invasive imaging. Here, we will focus our attention on the state-of-the-art of physically-triggered nanosystems based on graphene and two-dimensional nanomaterials for cancer therapy and diagnosis. The physical triggers include light, temperature, magnetic and electric fields.

Cancer cell–nanomaterial interface: role of geometry and surface charge of nanocomposites in the capture efficiency and cell viability

The nanomaterial–cell interface plays an important role in biodetection and therapy. The experimental results in this study indicated that the magnetic nanocomposites with strong positive surface charge but different geometry interacted with cancer cells in different ways, leading to various cell capture efficiency and cytotoxicity.

Safety Assessment of Graphene-Based Materials: Focus on Human Health and the Environment

Graphene and its derivatives are heralded as "miracle" materials with manifold applications in different sectors of society from electronics to energy storage to medicine. The increasing exploitation of graphene-based materials (GBMs) necessitates a comprehensive evaluation of the potential impact of these materials on human health and the environment. Here, we discuss synthesis and characterization of GBMs as well as human and environmental hazard assessment of GBMs using in vitro and in vivo model systems with the aim to understand the properties that underlie the biological effects of these materials; not all GBMs are alike, and it is essential that we disentangle the structure-activity relationships for this class of materials.

Redox-responsive hyaluronic acid-functionalized graphene oxide nanosheets for targeted delivery of water-insoluble cancer drugs

Background

Gefitinib (Gef), an important epidermal growth factor receptor (EGFR), is used to treat lung cancer, but low water solubility and poor bioavailability severely limit its application in cancer therapy.

Methods

In this study, nanographene oxide (NGO) was decorated with hyaluronic acid (HA) by a linker cystamine dihydrochloride containing disulfide bonds (-SS-), followed by the incorporation of gefitinib, thus, constructing a HA-functionalized GO-based gefitinib delivery system (NGO-SS-HA-Gef). Subsequently, studies of biological experiments in vitro and in vivo were performed to investigate the therapeutic effect of the system in lung cancer.

Results

The HA-grafted GO nanosheets possessed enhanced physiological stability, admirable biocompatibility, and no obvious side effects in mice and could act as a nanocarrier for the delivery of gefitinib to tumor. Cellular uptake and intracellular cargo release assays showed that the uptake of NGO-SS-HA by A549 cells was facilitated via CD44 receptor-mediated endocytosis, and that more drug was released from NGO-SS-HA in the presence of GSH than in the absence of GSH. The target-specific binding of NGO-SS-HA to cancer cells with redox-responsive cargo release significantly enhanced the abilities of gefitinib-loaded GO nanosheets to induce cell apoptosis, suppress cell proliferation, and inhibit tumor growth in lung cancer cell-bearing mice.

Conclusion

The results demonstrated the potential utility of NGO-SS-HA-Gef for therapeutic applications in the treatment of lung cancer.

Graphene oxide induces p62/SQSTM-dependent apoptosis through the impairment of autophagic flux and lysosomal dysfunction in PC12 cells

Graphene oxide (GO), as a two-dimensional carbon nanosheet, has been extensively studied for potential biomedical applications due to its notable properties. Although a growing number of studies have investigated the adverse effects of GO nanosheets, the available toxicity data concerning GO's effect on the neuronal cells remain highly limited. In this work, we systematically investigated the toxic responses of commercially available GO on a rat pheochromocytoma-derived PC12 cell line, which was an ideal in vitro model to study the neurotoxicity of GO. GO exerted a significant toxic effect on PC12 cells in a dose- and time-dependent manner. GO treatments under doses of 40, 50, and 60 μg/mL triggered an autophagic response and the blockade of autophagic flux via disrupting lysosome degradation capability. Caspase 9-mediated apoptosis was also observed in GO-treated cells. Moreover, GO-induced apoptosis was relevant to the aberrant accumulation of autophagy substrate p62/SQSTM. Inhibitionofthe accumulation of autophagic substrate alleviated GO-caused apoptotic cell death. Our findings raise a concern for the putative biomedical applications of GO in the form of diagnostic and therapeutic tools, where its systematic biocompatibility should be thoroughly explored. STATEMENT OF SIGNIFICANCE: Graphene oxide (GO) has attracted considerable interests in biomedical fields, which also resulted in numerous safety risks to human bodies. It is urgently required to establish a paradigm for accurately evaluating their adverse effects in biological systems. This study thoroughly explored the neurotoxicity of GO in PC12 cells. We found GO triggered an increased autophagic response and the impairment of autophagic flux, which was functionally involved in cell apoptosis. Inhibitionofexcessive accumulation of autophagic cargo attenuated apoptotic cell death. Our findings highlight deep considerations on the regulation mechanism of autophagy-lysosomes-apotosis-axis, which will contribute to a better understanding of the neurotoxicity of graphene-family nanomaterials, and provide a new insight in the treatment of cancer cells at nanoscale levels.

A novel environmental fate of graphene oxide: Biodegradation by a bacterium Labrys sp. WJW to support growth

Graphene oxide (GO) is a new type of nanomaterial with unique physicochemical properties and diverse applications, whereas it poses potential risk to human and environment. By screening from natural soil exposed to GO in the laboratory, we successfully obtained a novel bacterium, Labrys sp. WJW, which was able to use GO as the sole carbon source for growth. Within 8 days, cell numbers increased 16.76 ± 3.21 folds using 100 mg/L GO as the carbon source by qPCR analysis. The bacterial biodegradation which resulted in formation of holes and functional group changes of GO was proved by Raman spectroscopy, atomic force microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy analyses. Aromatic intermediates with structures of benzoic acid and phenol were identified using gas chromatograph-mass spectrometry and liquid chromatography/time-of-flight/mass spectrometry. Combination of genomic and proteomic analyses were performed to explore the proteins associated with GO degradation. A total of 644 proteins were significantly shifted. Bioinformatics analysis indicated that part of the up-regulated proteins were related to oxidation, ring cleavage and intermediates transmembrane processes, and GO was supposed to be degraded to benzoate and further degraded for downstream processes. This study enriches our understanding and provides new insights into the environmental fate of GO.

Reduced graphene oxide triggered epithelial-mesenchymal transition in A549 cells

Graphene and its derivatives have exhibited wide potential applications in electronics, structural engineering and medicine. However, over utilization and untreated discharge may cause its distribution into environmental as well as biological chain, which raised the concerns of potential health risk as a potential hazard. Accumulating evidence has demonstrated that graphene derivatives induce lung fibrosis in vivo, so overall goal of this study was to explore the molecular mechanisms underlying the pulmonary fibrotic responses of reduced graphene oxide (rGO), using in vitro assays. Epithelial-mesenchymal transition (EMT) has profound effect on development of pulmonary fibrosis. Herein, we evaluated the EMT effect of rGO samples on A549 cells. Firstly, rGO penetrated through the A549 cells membrane into the cytosol by endocytosis and located in late endosome and/or lysosomes observed via transmission electron microscopy (TEM), and were well tolerant by cells. Secondly, rGO promoted the cell migration and invasion capacities at lower doses (below 10 μg/ml), but significantly inhibited the capacities at 20 μg/ml. Moreover, rGO-induced EMT were evidenced by decreased expression of epithelial marker like E-cadherin, β-catenin, Smad4 and increased expression of mesenchymal markers like Vimentin, VEGF-B, TWIST1. Based on our findings, it is supposed that rGO can effectively induce EMT through altering epithelial–mesenchymal transition markers in A549 cells.

Application of black phosphorus nanodots to live cell imaging

BACKGROUND

Black phosphorus (BP) has emerged as a novel class of nanomaterials owing to its unique optical and electronic properties. BP, a two-dimensional (2D) nanomaterial, is a structure where phosphorenes are stacked together in layers by van der Waals interactions. However, although BP nanodots have many advantages, their biosafety and biological effect have not yet been elucidated as compared to the other nanomaterials. Therefore, it is particularly important to assess the cytotoxicity of BP nanodots for exploring their potentials as novel biomaterials.

METHODS

BP nanodots were prepared by exfoliation with a modified ultrasonication-assisted solution method. The physicochemical properties of BP nanodots were characterized by transmission electron microscopy, dynamic light scattering, Raman spectroscopy, and X-ray diffractometry. In addition, the cytotoxicity of BP nanodots against C2C12 myoblasts was evaluated. Moreover, their cell imaging potential was investigated.

RESULTS

Herein, we concentrated on evaluating the cytotoxicity of BP nanodots and investigating their cell imaging potential. It was revealed that the BP nanodots were cytocompatible at a low concentration, although the cell viability was decreased with increasing BP nanodot concentration. Furthermore, our results demonstrated that the cells took up the BP nanodots, and the BP nanodots exhibited green fluorescence.

CONCLUSIONS

In conclusion, our findings suggest that the BP nanodots have suitable biocompatibility, and are promising candidates as fluorescence probes for biomedical imaging applications.

Graphene Family Materials in Bone Tissue Regeneration: Perspectives and Challenges

We have witnessed abundant breakthroughs in research on the bio-applications of graphene family materials in current years. Owing to their nanoscale size, large specific surface area, photoluminescence properties, and antibacterial activity, graphene family materials possess huge potential for bone tissue engineering, drug/gene delivery, and biological sensing/imaging applications. In this review, we retrospect recent progress and achievements in graphene research, as well as critically analyze and discuss the bio-safety and feasibility of various biomedical applications of graphene family materials for bone tissue regeneration.

pH-sensitive and biocompatible quercetin-loaded GO-PEA-HA carrier improved antitumour efficiency and specificity

A novel drug carrier was designed based on a new biomaterial, that is, graphene oxide (GO), to improve the efficiency and specificity of anticancer drug. In this study, GO was successively modified with polyetheramine (PEA) and hyaluronic acid (HA). The carrier was utilized to load an antitumor component, that is, quercetin (Que), which was derived from traditional Chinese medicine, namely the pagoda tree flower bud. This drug delivery system (DDS) exhibited pH sensibility under subacid condition and good biocompatibility even when GO concentration reached 350 μg/mL. Moreover, the antitumor efficacy was doubly improved and more long-acting compared with Que alone. Results show that the GO-based material has potential clinical applications for antitumor drug delivery.

Occupational exposure to graphene based nanomaterials: risk assessment

Graphene-based materials (GBMs) are a family of novel materials including graphene, few layer graphene (FLG), graphene oxide (GO), reduced graphene oxide (rGO) and graphene nanoplatelets (GNP). Currently, the risk posed by them to human health is associated mainly with the occupational exposure during their industrial and small-scale production or waste discharge. The most significant occupational exposure routes are inhalation, oral, cutaneous and ocular, inhalation being the majorly involved and most studied one. This manuscript presents a critical up-to-date review of the available in vivo toxicity data of the most significant GBMs, after using these exposure routes. The few in vivo inhalation toxicity studies (limited to 5-days of repeated exposure and only one to 5 days per week for 4 weeks) indicate inflammatory/fibrotic effects at the pulmonary level, not always reversible after 14/90 days. More limited in vivo data are available for the oral and ocular exposure routes, whereas the studies on cutaneous toxicity are at the initial stage. A long persistence of GBMs in rodents is recorded, while contradictory genotoxic data are reported. Data gap identification is also provided. Based on the available data, the occupational exposure limit cannot be determined. More experimental toxicity studies according to specific guidelines (tentatively validated for nanomaterials) and more information on the actual occupational exposure level to GBMs are needed. Furthermore, ADME (Absorption, Distribution, Metabolism, Excretion), genotoxicity, developmental and reproductive toxicity data related to the occupational exposure to GBMs have to be implemented. In addition, sub-chronic and/or chronic studies are still needed to completely exclude other toxic effects and/or carcinogenicity.

Probabilistic approach for the risk assessment of nanomaterials: A case study for graphene nanoplatelets

An experimental probabilistic approach for health risk assessment was applied for graphene nanoplatelets (GNPs). The hazard assessment indicated a low level of toxicity for the GNPs. The benchmark dose method, based on sub-chronic and chronic inhalation exposure studies, was used to quantify a guidance value (BMC_h) for occupational inhalation exposure to GNPs, expressed as a lognormal distribution with a geometric mean ± geometric standard deviation of 0.212 ± 7.79 mg/m³ and 9.37 × 10⁴ ± 7.6 particle/cm³. Exposure scenarios (ES) were defined based on the scientific literature for large-scale production (ES1) and manufacturing (ES2) of GNPs; a third ES, concerning in-lab handling of GNPs (ES3) was based on results of experiments performed for this study. A probability distribution function was then assumed for each ES. The risk magnitude was calculated using a risk characterization ratio (RCR), defined as the ratio of the exposure distributions and the BMC_h distribution. All three ES resulted in RCR distributions ≥1 (i.e. risk present); however, none of the ES had a statistically significant level of risk at a 95% confidence interval. A sensitivity analysis indicated that ∼75% of the variation in the RCR distributions was due to uncertainties in the BMC_h calculation.

In vivo toxicological evaluation of graphene oxide nanoplatelets for clinical application

Background

Graphene is considered as a wonder material; it is the strongest material on the planet, super-elastic, and conductive. Its application in biomedicine is huge, with a multibillion-dollar industry, and will revolutionize the diagnostic and treatment of diseases. However, its safety and potential toxicity is the main challenge.

Methods

This study assessed the potential toxicity of graphene oxide nanoplatelets (GONs) in an in vivo animal model using systemic, hematological, biochemical, and histopathological examinations. Normal saline (control group) or GONs (3–6 layers, lateral dimension=5–10 μm, and thickness=0.8–2 nm) at dose rate of 50, 150, or 500 mg/kg were intraperitoneally injected into adult male Wistar rats (n=5) every 48 hours during 1 week to receive each animal a total of four doses. The animals were allowed 2 weeks to recover after the last dosing. Then, animals were killed and the blood was collected for hematological and biochemical analysis. The organs including the liver, kidney, spleen, lung, intestine, brain, and heart were harvested for histopathological evaluations.

Results

The results showed GONs prevented body weight gain in animals after 21 days, treated at 500 mg/kg, but not in the animals treated at 150 or 50 mg/kg GONs. The biochemical analysis showed a significant increase in total bilirubin, with a significant decrease in triglycerides and high-density lipoprotein in animals treated at 500 mg/kg. Nonetheless, other hematological and biochemical parameters remained statistically insignificant in all GONs treated animals. The most common histopathological findings in the visceral organs were granulomatous reaction with giant cell formation and accumulation of GONs in capsular regions. Also, small foci of neuronal degeneration and necrosis were the most outstanding findings in the brain, including the cerebellum.

Conclusion

In conclusion, this study shows that GONs without functionalization are toxic. The future study is a comparison of the functionalized with non-functionalized GONs.

Assessing and Mitigating the Hazard Potential of Two-Dimensional Materials

The family of two-dimensional (2D) materials is comprised of a continually expanding palette of unique compositions and properties with potential applications in electronics, optoelectronics, energy capture and storage, catalysis, and nanomedicine. To accelerate the implementation of 2D materials in widely disseminated technologies, human health and environmental implications need to be addressed. While extensive research has focused on assessing the toxicity and environmental fate of graphene and related carbon nanomaterials, the potential hazards of other 2D materials have only recently begun to be explored. Herein, the toxicity and environmental fate of postcarbon 2D materials, such as transition metal dichalcogenides, hexagonal boron nitride, and black phosphorus, are reviewed as a function of their preparation methods and surface functionalization. Specifically, we delineate how the hazard potential of 2D materials is directly related to structural parameters and physicochemical properties and how experimental design is critical to the accurate elucidation of the underlying toxicological mechanisms. Finally, a multidisciplinary approach for streamlining the hazard assessment of emerging 2D materials is outlined, thereby providing a pathway for accelerating their safe use in a range of technologically relevant contexts.