Effects of Reduced Graphene Oxides on Apoptosis and Cell Cycle of Glioblastoma Multiforme

Neurodiagnostic and neurotherapeutic potential of graphene nanomaterials

Graphene has emerged as a highly promising nanomaterial for a variety of advanced technologies, including batteries, energy, electronics, and biotechnologies. Its recent contribution to neurotechnology is particularly noteworthy because its superior conductivity, chemical resilience, biocompatibility, thermal stability, and scalable nature make it well-suited for measuring brain activity and plasticity in health and disease. Graphene-mediated compounds are microfabricated in two central methods: chemical processes with natural graphite and chemical vapor deposition of graphene in a film form. They are widely used as biosensors and bioelectronics for neurodiagnostic and neurotherapeutic purposes in several brain disorders, such as Parkinson's disease, stroke, glioma, epilepsy, tinnitus, and Alzheimer's disease. This review provides an overview of studies that have demonstrated the technical advances of graphene nanomaterials in neuroscientific and clinical applications. We also discuss current limitations and future demands in relation to the clinical application of graphene, highlighting its potential technological and clinical significance for treating brain disorders. Our review underscores the potential of graphene nanomaterials as powerful tools for advancing the understanding of the brain and developing new therapeutic strategies.

The protective effect of silver nanoparticles' on epithelial cornea cells against ultraviolet is accompanied by changes in calcium homeostasis and a decrease of the P2X7 and P2Y2 receptors

PURPOSE

The aim of the study was to evaluate the effect of silver nanoparticles hydrocolloids (AgNPs) on human corneal epithelial cells. Epithelial cells form the outermost and the most vulnerable to environmental stimuli layer of the cornea in the eye. Mechanical stress, UV radiation, and pathogens such as bacteria, viruses, and parasites challenge the fragile homeostasis of the eye. To help combat stress, infection, and inflammation wide portfolio of interventions is available. One of the oldest treatments is colloidal silver. Silver nanoparticle suspension in water is known for its anti-bacterial anti-viral and antiprotozoal action. However, AgNPs interact also with host cells, and the character of the interplay between corneal cells and silver seeks investigation.

METHODS

The human epithelial corneal cell line (HCE-2) was cultured in vitro, treated with AgNPs, and subjected to UV. The cell's viability, migration, calcium concentration, and expression/protein level of selected proteins were investigated by appropriate methods including cytotoxicity tests, "wound healing" assay, Fluo8/Fura2 AM staining, qRT-PCR, and western blot.

RESULTS

Incubation of human corneal cells (HCE-2) with AgNP did not affect cells viability but limited cells migration and resulted in altered calcium homeostasis, decreased the presence of ATP-activated P2X7, P2Y2 receptors, and enhanced the expression of PACAP. Furthermore, AgNPs pretreatment helped restrain some of the deleterious effects of UV irradiation. Interestingly, AgNPs had no impact on the protein level of ACE2, which is important in light of potential SARS-CoV-2 entrance through the cornea.

CONCLUSIONS

Silver nanoparticles are safe for corneal epithelial cells in vitro.

Graphene- and MXene-based materials for neuroscience: diagnostic and therapeutic applications

MXenes and graphene are two-dimensional materials that have gained increasing attention in neuroscience, particularly in sensing, theranostics, and biomedical engineering. Various composites of graphene and MXenes with fascinating thermal, optical, magnetic, mechanical, and electrical properties have been introduced to develop advanced nanosystems for diagnostic and therapeutic applications, as exemplified in the case of biosensors for neurotransmitter detection. These biosensors display high sensitivity, selectivity, and stability, making them promising tools for neuroscience research. MXenes have been employed to create high-resolution neural interfaces for neuroelectronic devices, develop neuro-receptor-mediated synapse devices, and stimulate the electrophysiological maturation of neural circuits. On the other hand, graphene/derivatives exhibit therapeutic applicability in neuroscience, as exemplified in the case of graphene oxide for targeted delivery of therapeutic agents to the brain. While MXenes and graphene have potential benefits in neuroscience, there are also challenges/limitations associated with their use, such as toxicity, environmental impacts, and limited understanding of their properties. In addition, large-scale production and commercialization as well as optimization of reaction/synthesis conditions and clinical translation studies are very important aspects. Thus, it is important to consider the use of these materials in neuroscience research and conduct further research to obtain an in-depth understanding of their properties and potential applications. By addressing issues related to biocompatibility, long-term stability, targeted delivery, electrical interfaces, scalability, and cost-effectiveness, MXenes and graphene have the potential to greatly advance the field of neuroscience and pave the way for innovative diagnostic and therapeutic approaches for neurological disorders. Herein, recent advances in therapeutic and diagnostic applications of graphene- and MXene-based materials in neuroscience are discussed, focusing on important challenges and future prospects.

Theranostic Applications of 2D Graphene-Based Materials for Solid Tumors Treatment

Solid tumors are a leading cause of cancer-related deaths globally, being characterized by rapid tumor growth and local and distant metastases. The failures encountered in cancer treatment are mainly related to the complicated biology of the tumor microenvironment. Nanoparticles-based (NPs) approaches have shown the potential to overcome the limitations caused by the pathophysiological features of solid cancers, enabling the development of multifunctional systems for cancer diagnosis and therapy and allowing effective inhibition of tumor growth. Among the different classes of NPs, 2D graphene-based nanomaterials (GBNs), due to their outstanding chemical and physical properties, easy surface multi-functionalization, near-infrared (NIR) light absorption and tunable biocompatibility, represent ideal nanoplatforms for the development of theranostic tools for the treatment of solid tumors. Here, we reviewed the most recent advances related to the synthesis of nano-systems based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), for the development of theranostic NPs to be used for photoacoustic imaging-guided photothermal-chemotherapy, photothermal (PTT) and photodynamic therapy (PDT), applied to solid tumors destruction. The advantages in using these nano-systems are here discussed for each class of GBNs, taking into consideration the different chemical properties and possibility of multi-functionalization, as well as biodistribution and toxicity aspects that represent a key challenge for their translation into clinical use.

Functional Graphene for Peritumoral Brain Microenvironment Modulation Therapy in Glioblastoma

Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water-stable rGO-PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti-invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO-PEI_UT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti-invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti-invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.

Electrostatic polarization fields trigger glioblastoma stem cell differentiation

Over the last few years it has been understood that the interface between living cells and the underlying materials can be a powerful tool to manipulate cell functions. In this study, we explore the hypothesis that the electrical cell/material interface can regulate the differentiation of cancer stem-like cells (CSCs). Electrospun polymer fibres, either polyamide 66 or poly(lactic acid), with embedded graphene nanoplatelets (GnPs), have been fabricated as CSC scaffolds, providing both the 3D microenvironment and a suitable electrical environment favorable for CSCs adhesion, growth and differentiation. We have investigated the impact of these scaffolds on the morphological, immunostaining and electrophysiological properties of CSCs extracted from human glioblastoma multiform (GBM) tumor cell line. Our data provide evidence in favor of the ability of GnP-incorporating scaffolds to promote CSC differentiation to the glial phenotype. Numerical simulations support the hypothesis that the electrical interface promotes the hyperpolarization of the cell membrane potential, thus triggering the CSC differentiation. We propose that the electrical cell/material interface can regulate endogenous bioelectrical cues, through the membrane potential manipulation, resulting in the differentiation of CSCs. Material-induced differentiation of stem cells and particularly of CSCs, can open new horizons in tissue engineering and new approaches to cancer treatment, especially GBM.

The Anticancer Efficacy of Thiourea-Mediated Reduced Graphene Oxide Nanosheets against Human Colon Cancer Cells (HT-29)

The current research focuses on the fabrication of water-soluble, reduced graphene oxide (rGO) employing thiourea (T) using a simple cost-effective method, and subsequently examining its anticancer characteristics. The cytotoxicity caused by graphene oxide (GO) and T-rGO is investigated in detail. Biological results reveal a concentration-dependent toxicity of GO and T-rGO in human colon cancer cells HT-29. A decrease in cell viability alongside DNA fragmentation is observed. Flow cytometry analysis confirms the cytotoxic effects. The novelty in this work is the use of raw graphite powder, and oxidants such as KMNO₄, NaNO₃, and 98 percent H₂SO₄ to produce graphene oxide by a modified Hummers method. This study demonstrates a simple and affordable procedure for utilising thiourea to fabricate a water-soluble reduced graphene oxide, which will be useful in a variety of biomedical applications.

Reduced Graphene Oxide Modulates the FAK-Dependent Signaling Pathway in Glioblastoma Multiforme Cells In Vitro

Aggressive invasiveness is a common feature of malignant gliomas, despite their high level of tumor heterogeneity and possible diverse cell origins. Therefore, it is important to explore new therapeutic methods. In this study, we evaluated and compared the effects of graphene (GN) and reduced graphene oxides (rGOs) on a highly invasive and neoplastic cell line, U87. The surface functional groups of the GN and rGO flakes were characterized by X-ray photoelectron spectroscopy. The antitumor activity of these flakes was obtained by using the neutral red assay and their anti-migratory activity was determined using the wound healing assay. Further, we investigated the mRNA and protein expression levels of important cell adhesion molecules involved in migration and invasiveness. The rGO flakes, particularly rGO/ATS and rGO/TUD, were found highly toxic. The migration potential of both U87 and Hs5 cells decreased, especially after rGO/TUD treatment. A post-treatment decrease in mobility and FAK expression was observed in U87 cells treated with rGO/ATS and rGO/TUD flakes. The rGO/TUD treatment also reduced β-catenin expression in U87 cells. Our results suggest that rGO flakes reduce the migration and invasiveness of U87 tumor cells and can, thus, be used as potential antitumor agents.

The Reduced Graphene Oxide (rGO) Induces Apoptosis, Autophagy and Cell Cycle Arrest in Breast Cancer Cells

Reduced graphene oxide (rGO) has already been reported as a potential cytostatic agent in various cancers. However, the mechanisms underlying rGO’s cytotoxicity are still insufficiently understood. Thus, the aim of the study was to investigate the molecular and cellular effects of rGO in breast cancer. Given this, two cell lines, MDA-MB-231 and ZR-75-1, were analyzed using MTT test, flow cytometry and Western blot assay. Incubation with rGO resulted in a multitude of effects, including the stimulation of autophagy, cell cycle arrest and, finally, the apoptotic death of cancer cells. Notably, rGO had minimal effect on normal human fibroblasts. Apoptosis in cancer cells was accompanied by decreased mitochondrial membrane potential, the deregulated expression of mitochondrial proteins and the activation of caspase 9 and caspase 3, suggesting that rGO predominantly induced apoptosis via intrinsic pathway. The analysis of LC3 protein expression revealed that rGO also caused autophagy in breast cancer cells. Moreover, rGO treatment resulted in cell cycle arrest, which was accompanied by deregulated p21 expression. Altogether, rGO seems to have multidirectional cytostatic and cytotoxic effects in breast cancer cells, making it a promising agent worthy of further investigation.

Continuous flow fabrication of green graphene oxide in aqueous hydrogen peroxide

Highly processible graphene oxide (GO) has a diversity of applications as a material readily dispersed in aqueous media. However, methods for preparing such free-standing GO use hazardous and toxic reagents and generate significant waste streams. This is an impediment for uptake of GO in any application, for developing sustainable technologies and industries, and overcoming this remains a major challenge. We have developed a robust scalable continuous flow method for fabricating GO directly from graphite in 30% aqueous hydrogen peroxide which dramatically minimises the generation of waste. The process features the continuous flow thin film microfluidic vortex fluidic device (VFD), operating at specific conditions while irradiated sequentially by UV LED than a NIR pulsed laser. The resulting 'green' graphene oxide (gGO) has unique properties, possessing highly oxidized edges with large intact sp² domains which gives rise to exceptional electrical and optical properties, including purple to deep blue emission of narrow full width at half maximum (<35 nm). Colloidally stable gGO exhibits cytotoxicity owing to the oxidised surface groups while solid-state films of gGO are biocompatible. The continuous flow method of generating gGO also provides unprecedented control of the level of oxidation and its location in the exfoliated graphene sheets by harnessing the high shear topological fluid flows in the liquid, and varying the wavelength, power and pulse frequency of the light source.

Graphene oxide induces autophagy and apoptosis via ROS-dependent AMPK/mTOR/ULK-1 pathway in colorectal cancer cells

Aim: To investigate the anticancer effects and action mechanism of graphene oxide (GO) in colorectal cancer (CRC). Materials & methods: Anticancer effects and mechanisms of GO in CRC were investigated both in vivo and in vitro. Results: GO significantly inhibited tumor growth both in vitro and in vivo. GO was able to enter HCT116 cells through endocytosis. GO treatment resulted in cytotoxicity, reactive oxygen species (ROS) production, apoptosis, autophagy and activation of the AMPK/mTOR/ULK1 signal pathway. However, ROS scavenger N-acetylcysteine (NAC) attenuated the above effects and restored the effects of GO on protein expressions related to apoptosis, autophagy and AMPK/mTOR/ULK1 signal pathways. Conclusion: GO exerts anticancer effects against CRC via ROS-dependent AMPK/mTOR/ULK-1 pathway-related autophagy and apoptosis.

The potential of Graphene Oxide and reduced Graphene Oxide in diagnosis and treatment of Cancer

Nanotechnology is a pioneer field of study; for engineering smart nanosystems in targeted diagnosis and treatment in cancer therapy. The potent therapy for different kinds of solid tumors should ideally target individually the cancerous cells and tissue with no impact on healthy cells in the body. Nano-sized graphene oxide (GO) and reduced graphene oxide (rGO) have phenomenal chemical versatility, high surface area ratio, and supernatural physical properties. The synergistic effects caused by the well-defined assembly of GO and rGO surface generate not only essential optical, mechanical, but also electronic behaviors. Developing novel multifunctional hybrid nanoparticles with great potential is highly considered in multimodal cancer treatment. GO, and rGO are engineered as a programmable targeting delivery system and combed with photonic energy they utilize in photothermal therapy. Its remarkable properties indicated its applications as a biosensor, bio-imaging for cancer diagnosis. In this current review, we show a remarkable highlight about GO, rGO, and discuss the notable applications for cancer diagnosis and treatment, and an overview of possible cellular signaling pathways that are affected by GO, rGO in cancer treatment.

The Role of Graphene Oxide Nanocarriers in Treating Gliomas

Gliomas are the most common primary malignant tumors of the central nervous system, and their conventional treatment involves maximal safe surgical resection combined with radiotherapy and temozolomide chemotherapy; however, this treatment does not meet the requirements of patients in terms of survival and quality of life. Graphene oxide (GO) has excellent physical and chemical properties and plays an important role in the treatment of gliomas mainly through four applications, viz. direct killing, drug delivery, immunotherapy, and phototherapy. This article reviews research on GO nanocarriers in the treatment of gliomas in recent years and also highlights new ideas for the treatment of these tumors.

MicroRNA Delivery by Graphene-Based Complexes into Glioblastoma Cells

Glioblastoma (GBM) is the most common primary and aggressive tumour in brain cancer. Novel therapies, despite achievements in chemotherapy, radiation and surgical techniques, are needed to improve the treatment of GBM tumours and extend patients’ survival. Gene delivery therapy mostly uses the viral vector, which causes serious adverse events in gene therapy. Graphene-based complexes can reduce the potential side effect of viral carries, with high efficiency of microRNA (miRNA) or antisense miRNA delivery to GBM cells. The objective of this study was to use graphene-based complexes to induce deregulation of miRNA level in GBM cancer cells and to regulate the selected gene expression involved in apoptosis. The complexes were characterised by Fourier transform infrared spectroscopy (FTIR), scanning transmission electron microscopy and zeta potential. The efficiency of miRNA delivery to the cancer cells was analysed by flow cytometry. The effect of the anticancer activity of graphene-based complexes functionalised by the miRNA sequence was analysed using 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxyanilide salt (XTT) assays at the gene expression level. The results partly explain the mechanisms of miRNA deregulation stress, which is affected by graphene-based complexes together with the forced transport of mimic miR-124, miR-137 and antisense miR-21, -221 and -222 as an anticancer supportive therapy.

Comparison of the Toxicity of Pristine Graphene and Graphene Oxide, Using Four Biological Models

There are numerous applications of graphene in biomedicine and they can be classified into several main areas: delivery systems, sensors, tissue engineering and biological agents. The growing biomedical field of applications of graphene and its derivates raises questions regarding their toxicity. We will demonstrate an analysis of the toxicity of two forms of graphene using four various biological models: zebrafish (Danio rerio) embryo, duckweed (Lemna minor), human HS-5 cells and bacteria (Staphylococcus aureus). The toxicity of pristine graphene (PG) and graphene oxide (GO) was tested at concentrations of 5, 10, 20, 50 and 100 µg/mL. Higher toxicity was noted after administration of high doses of PG and GO in all tested biological models. Hydrophilic GO shows greater toxicity to biological models living in the entire volume of the culture medium (zebrafish, duckweed, S. aureus). PG showed the highest toxicity to adherent cells growing on the bottom of the culture plates—human HS-5 cells. The differences in toxicity between the tested graphene materials result from their physicochemical properties and the model used. Dose-dependent toxicity has been demonstrated with both forms of graphene.

Effect of Elaeagnus umbellata (Thunb.) fruit extract on H2O2-induced oxidative and inflammatory responses in normal fibroblast cells

BACKGROUND

Elaeagnus umbellata is a plant commonly used in traditional Asian medicine for its many health benefits and strong antioxidative activity. Its therapeutic potential is believed to be connected to its effect on fibroblasts. This study aimed to investigate E. umbellata methanol-acetone extract's (EUE) defense against hydrogen peroxide (H2O2)-induced fibroblast damage.

METHODS

Because the main biologically active compounds of E. umbellata are water-insoluble, we evaluated the effects of methanol-acetone fruit extracts using liquid chromatography (for ascorbic acid and beta-carotene) and spectrophotometry (for lycopene and total phenolics). The extract's antioxidative activity was measured using DPPH radical inhibition, and EUE's effect on human fibroblasts was also evaluated. We assessed the metabolic activity and apoptosis of HFFF-2 fibroblasts exposed to EUE and/or H2O2using the XTT test and flow cytometry, respectively. Superoxide dismutase activity and reactive oxygen species (ROS) production were evaluated using colorimetric and fluorometric assays, respectively. We measured pro-inflammatory cytokine (MIF, fractalkine, MCP-4, BLC, GCP-2, NAP-2, Eotaxin-2, and Eotaxin-3) expression in HFFF-2 cells using immunocytochemistry.

RESULT

The extract increased HFFF-2 cell proliferation and reduced cell death caused by H2O2-induced stress. H2O2-treated fibroblasts had greater ROS production than cells treated with both H2O2 and EUE. Additionally, the group treated with H2O2 alone showed higher pro-inflammatory cytokine (MIF, MCP-4, NAP-2, Eotaxin-2, and Eotaxin-3) expression.

CONCLUSION

EUE protected human fibroblasts from H2O2-induced oxidative stress and reduced the fibroblast-mediated inflammatory response triggered by ROS.

Reduced Graphene Oxides Modulate the Expression of Cell Receptors and Voltage-Dependent Ion Channel Genes of Glioblastoma Multiforme

The development of nanotechnology based on graphene and its derivatives has aroused great scientific interest because of their unusual properties. Graphene (GN) and its derivatives, such as reduced graphene oxide (rGO), exhibit antitumor effects on glioblastoma multiforme (GBM) cells in vitro. The antitumor activity of rGO with different contents of oxygen-containing functional groups and GN was compared. Using FTIR (fourier transform infrared) analysis, the content of individual functional groups (GN/exfoliation (ExF), rGO/thermal (Term), rGO/ammonium thiosulphate (ATS), and rGO/ thiourea dioxide (TUD)) was determined. Cell membrane damage, as well as changes in the cell membrane potential, was analyzed. Additionally, the gene expression of voltage-dependent ion channels (clcn3, clcn6, cacna1b, cacna1d, nalcn, kcne4, kcnj10, and kcnb1) and extracellular receptors was determined. A reduction in the potential of the U87 glioma cell membrane was observed after treatment with rGO/ATS and rGO/TUD flakes. Moreover, it was also demonstrated that major changes in the expression of voltage-dependent ion channel genes were observed in clcn3, nalcn, and kcne4 after treatment with rGO/ATS and rGO/TUD flakes. Furthermore, the GN/ExF, rGO/ATS, and rGO/TUD flakes significantly reduced the expression of extracellular receptors (uPar, CD105) in U87 glioblastoma cells. In conclusion, the cytotoxic mechanism of rGO flakes may depend on the presence and types of oxygen-containing functional groups, which are more abundant in rGO compared to GN.

Graphene oxide nanofilm and chicken embryo extract decrease the invasiveness of HepG2 liver cancer cells

Background

The extracellular matrix (ECM) is a mosaic of various structural and functional proteins that cooperate with the cell, regulate adhesion, and consequently manage its further fate. Liver destruction is accompanied by a disruption of the physicochemical properties of the ECM which deregulates the cell–ECM interaction and can lead to uncontrolled proliferation and neoplastic transformation of cells. Therefore, it can be assumed that ECM modification and restoration of its characteristics for healthy tissue may counteract uncontrolled cell proliferation. The purpose of the presented research model was to optimise the physical characteristics of ECM by introducing a graphene oxide plane/nanofilm (nfGO) and enriching the cell environment with potentially missing proteins by adding a functional protein cocktail (chicken embryo liver extract) and determine the impact of these factors on cell–ECM cooperation and its consequences on adhesion, proliferation, and cell phase, which are factors of the invasiveness of cancer cells.

Results

Experiments were performed with non-cancer HS-5 cells and liver cancer cells HepG2 and C3A. The cells were divided into four groups: (1) control, (2) cultured on nfGO, (3) cultured with the addition of chicken embryo liver extract (CELE) and (4) cultured on the nfGO with the addition of CELE. CELE contained 1735 proteins; the top 57 of these proteins have been presented. The use of nfGO as well as CELE and nfGO + CELE reduced the proliferation of HepG2 cancer cells to the greatest extent; this is in contrast to non-cancer cells and also to C3A cancer cells. Furthermore, the combined use of the CELE protein cocktail and GO substrate effectively resulted in a decrease in the population of HepG2 cells in the G0/G1 phase and an increase of the population in G2/M. Molecular analysis of HepG2 cancer cells also showed an increase in the expression of genes responsible for adhesion such as focal adhesion kinase (fak), e-cadherin, and n-cadherin and a decrease in β-catenin, which is considered a proto-oncogene.

Conclusions

Studies have shown that both the GO surface structure on which the cells are grown as well as the presence of a multi-component natural cocktail of regulatory proteins, can modify the expression of integrins, increase adhesion and, as a consequence, proliferation and the cell cycle—entering the resting phase. For the first time, it has been documented that hepatic cancer cells of the HepG2 line under the influence of stimuli derived from mimic ECM (graphene oxide) in interaction with a unique protein complex derived from chicken liver embryo decreased of the invasiveness of cancer cells.

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.

On the rapid in situ oxidation of two-dimensional V2CTz MXene in culture cell media and their cytotoxicity

The plethora of emerging two-dimensional (2D) materials exhibit wide potential application in novel technologies and advanced devices. However, their stability in environmental conditions could be an issue, affecting their application possibilities and posing health risks. Moreover, their decomposed leftovers can also induce a negative influence on human health. In particular, transition metal carbides commonly referred to as MXenes are susceptible to environmental oxidation being decomposed toward transition metal oxides and carbide-derived carbon. In this study we focused on the oxidation-state-related in vitro cytotoxicity of delaminated V₂CT_z onto immortalized keratinocytes (HaCaT) and malignant melanoma (A375) human cell lines. Due to the fact, that the V₂CT_x MXenes are least stable from all known obtained MXenes up to date, the vanadium ones were a practical choice to visualize the oxidation-cytotoxic correlation keeping the standards of 24-48 h of cell culturing. We found that the oxidation of V₂CT_z highly increases their cytotoxicity toward human cells, which is also time and dose dependent. The identified mode of action relates to the cell cycle as well as cellular membrane disintegration through direct physicochemical interactions.

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.

Functionalized graphene oxide against U251 glioma cells and its molecular mechanism

Graphene and its derivatives with exceptional properties are being exploited for drug delivery and even combined therapies for enhanced antitumor activity and reduced side effects. However, the unfavorable surface chemistry of pristine graphene and reduced graphene oxide made them take covalent and non-covalent functionalization strategies to improve their biocompatibility. Although graphene oxide (GO) is soluble in water owing to its oxygen-containing groups such as carboxylic acid and hydroxyl groups, it is highly accepted when to be modified to improve its colloidal stability in physiological buffers in the presence of salts. In this work, we functionalized GO with Pluronic F127 molecules via non-covalent interaction and found that GO and PF127/GO nanohybrid with a concentration lower than 5 μg/ml have no obvious toxic effect on human astrocytes (AS) and human glioma (U251) cells. Anti-tumor drug doxorubicin (DOX) being loaded onto the PF127/GO nanocarriers by π-π stacking exhibited a high loading capacity of 0.83 mg/mg and loading efficiency of 83%. Our study confirmed that the PF127/GO/DOX (PGD) induced a higher apoptosis rate (12.27 ± 0.06%) of U251 cells than that of free DOX (8.20 ± 0.06%) (P < 0.05). Western blotting results indicated that PGD affected the MAPK signaling pathway and induced the intrinsic pathway of apoptosis for the activation of Caspase-3 in U251 cells, which may provide more evidence for the signal pathway of tumor-targeting therapy.

Graphene oxide suppresses the growth and malignancy of glioblastoma stem cell-like spheroids via epigenetic mechanisms

Background

Glioblastoma stem-like cells (GSCs) are hypothesized to contribute to self-renewal and therapeutic resistance in glioblastoma multiforme (GBM) tumors. Constituting only a small percentage of cancer cells, GSCs possess “stem-like”, tumor-initiating properties and display resistance to irradiation and chemotherapy. Thus, novel approaches that can be used to suppress GSCs are urgently needed. A new carbon material—graphene oxide (GO), has been reported to show potential for use in tumor therapy. However, the exact effect of GO on GSCs and the inherent mechanism underlying its action are not clear. In this study, we aimed to investigate the usefulness of GO to inhibit the growth and promote the differentiation of GSCs, so as to suppress the malignancy of GBM.

Methods

In vitro effects of GO on sphere-forming ability, cell proliferation and differentiation were evaluated in U87, U251 GSCs and primary GSCs. The changes in cell cycle and the level of epigenetic modification H3K27me3 were examined. GO was also tested in vivo against U87 GSCs in mouse subcutaneous xenograft models by evaluating tumor growth and histological features.

Results

We cultured GSCs to explore the effect of GO and the underlying mechanism of its action. We found, for the first time, that GO triggers the inhibition of cell proliferation and induces apoptotic cell death in GSCs. Moreover, GO could promote the differentiation of GSCs by decreasing the expression of stem cell markers (SOX2 and CD133) and increasing the expression of differentiation-related markers (GFAP and β-III tubulin). Mechanistically, we found that GO had a striking effect on GSCs by inducing cell cycle arrest and epigenetic regulation. GO decreased H3K27me3 levels, which are regulated by EZH2 and associated with transcriptional silencing, in the promoters of the differentiation-related genes GFAP and β-III tubulin, thereby enhancing GSC differentiation. In addition, compared with untreated GSCs, GO-treated GSCs that were injected into nude mice exhibited decreased tumor growth in vivo.

Conclusion

These results suggested that GO could promote differentiation and reduce malignancy in GSCs via an unanticipated epigenetic mechanism, which further demonstrated that GO is a potent anti-GBM agent that could be useful for future clinical applications.

Graphene-Induced Transdifferentiation of Cancer Stem Cells as a Therapeutic Strategy against Glioblastoma

Glioblastoma (GBM) is an extremely malignant tumor of the central nervous system, characterized by low response to treatments and reoccurrence. This therapeutic resistance is believed to arise mostly from the presence of a subpopulation of tumorigenic stem cells, known as cancer stem cells (CSCs). In addition, the surrounding microenvironment is known to maintain CSCs, thus supporting tumor development and aggressiveness. This review focuses on a therapeutic strategy involving the stem cell trans-differentiating ability of graphene and its derivatives. Graphene distinguishes itself from other carbon-based nanomaterials due to an array of properties that makes it suitable for many purposes, from bioengineering to biomedical applications. Studies have shown that graphene is able to promote and direct the differentiation of CSCs. In addition, potential usage of graphene in GBM treatment represents a challenge in respect to its administration method. The present review also provides a general outlook of the potential side effects (e.g., cell toxicity) that graphene could have. Overall, this report discusses certain graphene-based therapeutic strategies targeting CSCs, which can be considered as prospective effective GBM treatments.

Synthesis, characterization, and anticancer activity of Schiff bases

Five Schiff bases, 2-((3-chlorophenylimino)methyl)-5-(diethylamino)phenol (L1), 2-((2,4-dichlorophenylimino)methyl)-5-(diethylamino)phenol (L2), 5-(diethylamino)-2-((3,5-dimethylphenylimino)methyl)phenol (L3), 2-((2-chloro-4-methylphenylimino)methyl)-5-(diethylamino)phenol (L4), and 5-(diethylamino)-2-((2,6-diethylphenylimino)methyl)phenol (L5) were synthesized and characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR spectroscopy. Three of the compounds (L1, L2, and L4) were analyzed by single crystal X-ray diffraction: L1 and L2 crystallized in orthorhombic P2₁2₁2₁ and Pca2₁ space group, respectively, while L4 crystallized in monoclinic P2₁/c space group. Theoretical investigations were performed for all the synthesized compounds to evaluate the structural details. Drug-DNA interaction studies results from UV-Vis spectroscopy and electrochemistry complement that the compounds bind to DNA through electrostatic interactions. The cytotoxicity of the synthesized compounds was studied against cancer cell lines (HeLa and MCF-7) and a normal cell line (BHK-21) by means of an MTT assay compared to carboplatin, featuring IC₅₀ values in the micromolar range. The pro-apoptotic mechanism for the active compound L5 was evaluated by fluorescence microscopy, cell cycle analysis, caspase-9 and -3 activity, reactive oxygen species production, and DNA binding studies that further strengthen the results of that L5 is a potent drug against cancer.Communicated by Ramaswamy H. Sarma.