Evaluation of the Cytotoxicity and Oxidative Stress Response of CeO2-RGO Nanocomposites in Human Lung Epithelial A549 Cells

Respiratory Toxicology of Graphene-Based Nanomaterials: A Review

Graphene-based nanomaterials (GBNs) consist of a single or few layers of graphene sheets or modified graphene including pristine graphene, graphene nanosheets (GNS), graphene oxide (GO), reduced graphene oxide (rGO), as well as graphene modified with various functional groups or chemicals (e.g., hydroxyl, carboxyl, and polyethylene glycol), which are frequently used in industrial and biomedical applications owing to their exceptional physicochemical properties. Given the widespread production and extensive application of GBNs, they can be disseminated in a wide range of environmental mediums, such as air, water, food, and soil. GBNs can enter the human body through various routes such as inhalation, ingestion, dermal penetration, injection, and implantation in biomedical applications, and the majority of GBNs tend to accumulate in the respiratory system. GBNs inhaled and substantially deposited in the human respiratory tract may impair lung defenses and clearance, resulting in the formation of granulomas and pulmonary fibrosis. However, the specific toxicity of the respiratory system caused by different GBNs, their influencing factors, and the underlying mechanisms remain relatively scarce. This review summarizes recent advances in the exposure, metabolism, toxicity and potential mechanisms, current limitations, and future perspectives of various GBNs in the respiratory system.

Evaluation of Antibacterial, Antioxidant, Anti-inflammatory and Anticancer Efficacy of Titanium-Doped Graphene Oxide Nanoparticles

INTRODUCTION

The current development of nanoparticles (NPs) with significant antibacterial properties, low cost and low toxicity has made it possible to develop novel techniques for treatments in the medical field. The titanium metal oxide, when combined with a carbonaceous material like graphene, which has excellent absorbing capacity, is efficient in loading drugs and thus helps in drug delivery and also in biomedical applications like anticancer, anti-inflammatory, antioxidant, and antibacterial activities.

MATERIALS AND METHODS

Titanium-doped graphene oxide nanoparticles (Ti/GO-NPs) were processed by the one-pot synthesis method; further characterization was performed by using UV-visible spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), field emission electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis and biomedical applications like anticancer, anti-inflammatory, antioxidant and antibacterial activities.

RESULTS

The synthesized end product of Ti/GO-NPs showed a creamy white appearance. Subsequent characterization studies of UV-Vis spectroscopy revealed a peak level of 373 nm at 24 hours and 404 nm after 48 hours. FT-IR analysis exhibited a broad absorption band within the range of 1000-3500 cm-1, which was attributed to various chemical compounds of C-Br, C-I stretching, C=C bending, S=O stretching, O=H stretching, C=C stretching, H bonded and OH stretching to different absorbance wavelength ranges. SEM analysis exhibited quasi-spherical-shaped Ti/GO-NPs with an average particle size of 50- 100 nm and EDX analysis showed the elemental composition of 32.3% titanium 43.9% oxygen and 2.5% carbon. The antibacterial activity showed moderate activity against Staphylococcus aureus and no activity against Pseudomonas aeruginosa, Enterococcus faecalis and E. coli. The antioxidant activity exhibited 88% at 50 µg/mL concentration, the anti-inflammatory activity revealed 80% at 80 µg/mL concentration and the anticancer activity showed 21% at 150 µg/mL concentration.

CONCLUSION

The characterization and biomedical application conclude that a combination of Ti/GO-NPs will be efficient in drug delivery. The study showed moderate antibacterial activity and significant antioxidant, anti-inflammatory and anticancer activities. Considering their physiochemical properties, absorption capacity and mechanism of drug delivery, Ti/GO-NPs can be incorporated into various applications in the medical field.

Nano-composite rGO-Ag-Cu-Ni mediated photocatalytic degradation of anthracene and benzene

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent, persistent, and carcinogenic pollutants continuously released in the atmosphere due to the rapid increase in population and industrialization worldwide. Hence, there is an ultimate rise in concern about eliminating the toxic PAHs and their related aromatic hydrocarbons from the air, water, and soil environment by employing efficient removal technologies using nanoparticles as a catalyst. Here, the degradation of selective PAHs viz., anthracene and benzene using laboratory synthesized rGO-Ag-Cu-Ni nanocomposite (catalyst) was studied. Characterization studies revealed the nanocomposites exhibited surface plasma resonance at 350 - 450 nm, confirming the presence of Ag, Cu, and Ni metal ions embedded on the reduced graphene substrate. It was found that the nanocomposites synthesized were spherical, amorphous in nature, and aggregated together with measurements ranging from 423 to 477 nm. An SEM-EDX analysis of the nanocomposite demonstrated that it contained 25.13% O, 14.24% Ni, 27.79% Cu, and 32.84% Ag, which confirms the synthesis of the nanocomposite. Crystalline, sharp nanocomposites of average size 17-41 nm with an average diameter of 118.5 nm (X-ray diffraction and DLS) were observed. FTIR spectra showed that the nanocomposites had the functional groups alkanes, alkenes, alkynes, carboxylic acids, and halogen derivatives. Batch adsorption studies revealed that the maximum degradation achieved at optimum nano-composite concentration of 10 μg/mL, pH value of 5, PAHs concentration of 2 μg/mL and effective irradiation source being UV radiations in the case of both benzene and anthracene pollutants. The degradation of benzene and anthracene followed Freundlich & Langmuir isotherm with the highest R2 value of 0.9894 & 0.9885, respectively. Adsorption kinetic studies under optimum conditions revealed that the adsorption of both benzene and anthracene followed Pseudo-second order kinetics. Antimicrobial studies revealed that the synthesized nano-composite exhibited potential antimicrobial activity against Gram positive bacterium (Bacillus subtilis, Staphylococcus aureus), Gram negative bacterium (Klebsiella pneumonia, Escherichia coli) and fungal strain (Aspergillus niger) respectively. Thus, the synthesized rGO-Ag-Cu-Ni nano-composite acts as an effective antimicrobial agent as well as a PAHs degrading agent, helping to overcome antibiotics resistance and to mitigate the overgrowing PAHs pollution in the environment.

Photocatalytic degradation of organic pollutants and inactivation of pathogens under visible light via SnO2/rGO composites

The domains of environmental cleanup and pathogen inactivation are particularly interesting in nanocomposites (NCs) due to their exceptional physicochemical properties. Tin oxide/reduced graphene oxide nanocomposites (SnO₂/rGO NCs) have potential uses in the biological and environmental fields, but little is known about them. This study aimed to investigate the photocatalytic activity and antibacterial efficiency of the nanocomposites. The co-precipitation technique was used to prepare all the samples. XRD, SEM, EDS, TEM, and XPS analyses were employed to characterize the physicochemical properties of SnO₂/rGO NCs for structural analysis. The rGO loading sample resulted in a decrease in the crystallite size of SnO₂ nanoparticles. TEM and SEM images demonstrate the firm adherence of SnO₂ nanoparticles to the rGO sheets. The chemical state and elemental composition of the nanocomposites were validated by the XPS and EDS data. Additionally, the visible-light active photocatalytic and antibacterial capabilities of the synthesized nanocomposites were assessed for the degradation of Orange II and methylene blue, as well as the suppression of the growth of S. aureus and E. coli. As a result, the synthesized SnO₂/rGO NCs are improved photocatalysts and antibacterial agents, expanding their potential in the fields of environmental remediation and water disinfection.

Graphene Oxide Nanosurface Reduces Apoptotic Death of HCT116 Colon Carcinoma Cells Induced by Zirconium Trisulfide Nanoribbons

Due to their chemical, mechanical, and optical properties, 2D ultrathin nanomaterials have significant potential in biomedicine. However, the cytotoxicity of such materials, including their mutual increase or decrease, is still not well understood. We studied the effects that graphene oxide (GO) nanolayers (with dimensions 0.1-3 μm and average individual flake thickness less than 1 nm) and ZrS₃ nanoribbons (length more than 10 μm, width 0.4-3 μm, and thickness 50-120 nm) have on the viability, cell cycle, and cell death of HCT116 colon carcinoma cells. We found that ZrS₃ exhibited strong cytotoxicity by causing apoptotic cell death, which was in contrast to GO. When adding GO to ZrS₃, ZrS₃ was significantly less toxic, which may be because GO inhibits the effects of cytotoxic hydrogen sulfide produced by ZrS₃. Thus, using zirconium trisulfide nanoribbons as an example, we have demonstrated the ability of graphene oxide to reduce the cytotoxicity of another nanomaterial, which may be of practical importance in biomedicine, including the development of biocompatible nanocoatings for scaffolds, theranostic nanostructures, and others.

A simple method for the preparation of CeO2with high antioxidant activity and wide application range

Cerium oxide (CeO₂) is a well-known antioxidant with the ability to scavenge reactive oxygen species due to its unique electronic structure and chemical properties. Although many methods to enhance the antioxidant activity of CeO₂have been reported, its antioxidant activity is still not high enough, and some enhancement effects are limited by the material concentration. There are also some CeO₂obtained with high antioxidant activity at high concentrations, which is not conducive to the application of biomedicine. Therefore, it is urgent to obtain CeO₂material with low cell cytotoxicity, high antioxidant activity and wide application range. In this work, rod-like metal organic framework derived CeO₂(CeO₂-MOF) was prepared by a simple method. Compared with the CeO₂nanorods prepared by hydrothermal method, it shows better antioxidant activity compared with the CeO₂nanorods prepared by hydrothermal method. Moreover, the advantage of CeO₂-MOF's antioxidant activity is not affected by the hydroxyl radical and material concentrations The reason why CeO₂-MOF has higher antioxidant activity should be attributed to its higher Ce³⁺content and larger specific surface area. In addition, CeO₂-MOF also exhibits low cytotoxicity to HeLa cells and PC12 cellsin vitro. The strategy of using MOF as a structural and compositional material to create CeO₂provides a new method to explore highly efficient and biocompatible CeO₂for practical applications.

Nanosafety Analysis of Graphene-Based Polyester Resin Composites on a Life Cycle Perspective

The use, production, and disposal of engineering nanomaterials (ENMs), including graphene-related materials (GRMs), raise concerns and questions about possible adverse effects on human health and the environment, considering the lack of harmonized toxicological data on ENMs and the ability of these materials to be released into the air, soil, or water during common industrial processes and/or accidental events. Within this context, the potential release of graphene particles, their agglomerates, and aggregates (NOAA) as a result of sanding of a battery of graphene-based polyester resin composite samples intended to be used in a building was examined. The analyzed samples were exposed to different weathering conditions to evaluate the influence of the weathering process on the morphology and size distribution of the particles released. Sanding studies were conducted in a tailored designed sanding bench connected to time and size resolving measurement devices. Particle size distributions and particle number concentration were assessed using an optical particle counter (OPC) and a condensation particle counter (CPC), respectively, during the sanding operation. A scanning electron microscope/energy dispersive X-ray (SEM/EDX) analysis was performed to adequately characterize the morphology, size, and chemical composition of the released particles. A toxicity screening study of pristine and graphene-based nanocomposites released using the aquatic macroinvertebrate Daphnia magna and relevant human cell lines was conducted to support risk assessment and decision making. The results show a significant release of nanoscale materials during machining operations, including differences attributed to the % of graphene and weathering conditions. The cell line tests demonstrated a higher effect in the human colon carcinoma cell line Caco2 than in the human fibroblasts (A549 cell line), which means that composites released to the environment could have an impact on human health and biota.

CeO2-Zn Nanocomposite Induced Superoxide, Autophagy and a Non-Apoptotic Mode of Cell Death in Human Umbilical-Vein-Derived Endothelial (HUVE) Cells

In this study, a nanocomposite of cerium oxide-zinc (CeO₂-Zn; 26 ± 11 nm) based on the antioxidant rare-earth cerium oxide (CeO₂) nanoparticles (NPs) with the modifier zinc (Zn) was synthesized by sintering method and characterized. Its bio-response was examined in human umbilical-vein-derived endothelial (HUVE) cells to get insight into the components of vascular system. While NPs of CeO₂ did not significantly alter cell viability up to a concentration of 200 µg/mL for a 24 h exposure, 154 ± 6 µg/mL of nanocomposite CeO₂-Zn induced 50% cytotoxicity. Mechanism of cytotoxicity occurring due to nanocomposite by its Zn content was compared by choosing NPs of ZnO, possibly the closest nanoparticulate form of Zn. ZnO NPs lead to the induction of higher reactive oxygen species (ROS) (DCF-fluorescence), steeper depletion in antioxidant glutathione (GSH) and a greater loss of mitochondrial membrane potential (MMP) as compared to that induced by CeO₂-Zn nanocomposite. Nanocomposite of CeO₂-Zn, on the other hand, lead to significant higher induction of superoxide radical (O₂^•−, DHE fluorescence), nitric oxide (NO, determined by DAR-2 imaging and Griess reagent) and autophagic vesicles (determined by Lysotracker and monodansylcadeverine probes) as compared to that caused by ZnO NP treatment. Moreover, analysis after triple staining (by annexin V-FITC, PI, and Hoechst) conducted at their respective IC50s revealed an apoptosis mode of cell death due to ZnO NPs, whereas CeO₂-Zn nanocomposite induced a mechanism of cell death that was significantly different from apoptosis. Our findings on advanced biomarkers such as autophagy and mode of cell death suggested the CeO₂-Zn nanocomposite might behave as independent nanostructure from its constituent ones. Since nanocomposites can behave independently of their constituent NPs/elements, by creating nanocomposites, NP versatility can be increased manifold by just manipulating existing NPs. Moreover, data in this study can furnish early mechanistic insight about the potential damage that could occur in the integrity of vascular systems.

One-Pot Synthesis of SnO2-rGO Nanocomposite for Enhanced Photocatalytic and Anticancer Activity

Metal oxide and graphene derivative-based nanocomposites (NCs) are attractive to the fields of environmental remediation, optics, and cancer therapy owing to their remarkable physicochemical characteristics. There is limited information on the environmental and biomedical applications of tin oxide-reduced graphene oxide nanocomposites (SnO₂-rGO NCs). The goal of this work was to explore the photocatalytic activity and anticancer efficacy of SnO₂-rGO NCs. Pure SnO₂ NPs and SnO₂-rGO NCs were prepared using the one-pot hydrothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), UV–Vis spectrometry, photoluminescence (PL), and Raman scattering microscopy were applied to characterize the synthesized samples. The crystallite size of the SnO₂ NPs slightly increased after rGO doping. TEM and SEM images show that the SnO₂ NPs were tightly anchored onto the rGO sheets. The XPS and EDX data confirmed the chemical state and elemental composition of the SnO₂-rGO NCs. Optical data suggest that the bandgap energy of the SnO₂-rGO NCs was slightly lower than for the pure SnO₂ NPs. In comparison to pure SnO₂ NPs, the intensity of the PL spectra of the SnO₂-rGO NCs was lower, indicating the decrement of the recombination rate of the surfaces charges (e⁻/h⁺) after rGO doping. Hence, the degradation efficiency of methylene blue (MB) dye by SnO₂-rGO NCs (93%) was almost 2-fold higher than for pure SnO₂ NPs (54%). The anticancer efficacy of SnO₂-rGO NCs was also almost 1.5-fold higher against human liver cancer (HepG2) and human lung cancer (A549) cells compared to the SnO₂ NPs. This study suggests a unique method to improve the photocatalytic activity and anticancer efficacy of SnO₂ NPs by fusion with graphene derivatives.

A Novel Green Preparation of Ag/RGO Nanocomposites with Highly Effective Anticancer Performance

The efficacy of current cancer therapies is limited due to several factors, including drug resistance and non-specific toxic effects. Due to their tuneable properties, silver nanoparticles (Ag NPs) and graphene derivative-based nanomaterials are now providing new hope to treat cancer with minimum side effects. Here, we report a simple, inexpensive, and eco-friendly protocol for the preparation of silver-reduced graphene oxide nanocomposites (Ag/RGO NCs) using orange peel extract. This work was planned to curtail the use of toxic chemicals, and improve the anticancer performance and cytocompatibility of Ag/RGO NCs. Aqueous extract of orange peels is abundant in phytochemicals that act as reducing and stabilizing agents for the green synthesis of Ag NPs and Ag/RGO NCs from silver nitrate and graphene oxide (GO). Moreover, the flavonoid present in orange peel is a potent anticancer agent. Green-prepared Ag NPs and Ag/RGO NCs were characterized by UV-visible spectrophotometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and dynamic light scattering (DLS). The results of the anticancer study demonstrated that the killing potential of Ag/RGO NCs against human breast cancer (MCF7) and lung cancer (A549) cells was two-fold that of pure Ag NPs. Moreover, the cytocompatibility of Ag/RGO NCs in human normal breast epithelial (MCF10A) cells and normal lung fibroblasts (IMR90) was higher than that of pure Ag NPs. This mechanistic study indicated that Ag/RGO NCs induce toxicity in cancer cells through pro-oxidant reactive oxygen species generation and antioxidant glutathione depletion and provided a novel green synthesis of Ag/RGO NCs with highly effective anticancer performance and better cytocompatibility.

Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells

Purpose

The use of cerium oxide nanoparticles (CeO₂ NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO₂ NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO₂ NPs in human retinal pigment epithelial cells (ARPE-19 cells).

Methods

Using the transmission electron microscope (TEM), the size distribution and shape of CeO₂ NPs were characterized. To explore the effect of CeO₂ NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO₂ NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H₂DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope.

Results

The cytotoxicity of 15 nm CeO₂ NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO₂ NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC).

Conclusion

CeO₂ NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO₂ NP-induced cytotoxicity.

Protective Effect of Cerium Oxide Nanoparticles on Human Sperm Function During Cryopreservation

The generation of reactive oxygen species during cryopreservation of human sperm has negative effects on the consistency of the thawed sperm. The antioxidant properties of cerium oxide nanoparticles (CeO₂NPs) may be useful for reducing cryodamage in thawed sperm. This research was conducted to determine the effects of CeO₂NPs on the quality and function of human sperm after thawing. Samples of semen obtained from 20 normozoospermic individuals were allocated to the following four groups: fresh, frozen control (sperm not treated with CeO₂NPs), and those exposed to 0.1 μg/mL CeO₂NPs (CeO₂-0.1), 1 μg/mL CeO₂NPs (CeO₂-1), and 5 μg/mL CeO₂NPs (CeO₂-5). Sperm parameters of motility, viability, membrane integrity, DNA fragmentation, protamination, malondialdehyde (MDA) levels, mitochondria membrane potential, and morphology were evaluated after the freezing-thawing process. The results showed that 0.1 μg/mL CeO₂NPs significantly (p < 0.05) improved the following human sperm parameters after thawing: progressive (44.6% ± 1.14% vs. 36.2% ± 1.24%) and total motility (60.9% ± 2.5% vs. 51.3% ± 2.5%), viability (67.9% ± 1.5% vs. 58.1% ± 1.5%), membrane functionality (66.1% ± 1.85% vs. 55.4% ± 1.85%), DNA integrity (30.8% vs. 24.04%), and protamination (69.85% ± 2.09% vs. 57.2% ± 2.09%) compared with the frozen control group. We observed the lowest MDA levels in the CeO₂-0.1 (3.06 ± 0.25 nmol/mL), CeO₂-1 (3.1 ± 0.25 nmol/mL), and CeO₂-5 (3.08 ± 0.25 nmol/mL) groups compared with the frozen control group (3.72 ± 0.25). Different concentrations of CeO₂NPs did not significantly change sperm normal morphology and mitochondria activity (p < 0.05).

SnO2-Doped ZnO/Reduced Graphene Oxide Nanocomposites: Synthesis, Characterization, and Improved Anticancer Activity via Oxidative Stress Pathway

BACKGROUND

Therapeutic selectivity and drug resistance are critical issues in cancer therapy. Currently, zinc oxide nanoparticles (ZnO NPs) hold considerable promise to tackle this problem due to their tunable physicochemical properties. This work was designed to prepare SnO2-doped ZnO NPs/reduced graphene oxide nanocomposites (SnO2-ZnO/rGO NCs) with enhanced anticancer activity and better biocompatibility than those of pure ZnO NPs.

MATERIALS AND METHODS

Pure ZnO NPs, SnO2-doped ZnO (SnO2-ZnO) NPs, and SnO2-ZnO/rGO NCs were prepared via a facile hydrothermal method. Prepared samples were characterized by field emission transmission electron microscopy (FETEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectrometer, and dynamic light scattering (DLS) techniques. Selectivity and anticancer activity of prepared samples were assessed in human breast cancer (MCF-7) and human normal breast epithelial (MCF10A) cells. Possible mechanisms of anticancer activity of prepared samples were explored through oxidative stress pathway.

RESULTS

XRD spectra of SnO2-ZnO/rGO NCs confirmed the formation of single-phase of hexagonal wurtzite ZnO. High resolution TEM and SEM mapping showed homogenous distribution of SnO2 and rGO in ZnO NPs with high quality lattice fringes without any distortion. Band gap energy of SnO2-ZnO/rGO NCs was lower compared to SnO2-ZnO NPs and pure ZnO NPs. The SnO2-ZnO/rGO NCs exhibited significantly higher anticancer activity against MCF-7 cancer cells than those of SnO2-ZnO NPs and ZnO NPs. The SnO2-ZnO/rGO NCs induced apoptotic response through the upregulation of caspase-3 gene and depletion of mitochondrial membrane potential. Mechanistic study indicated that SnO2-ZnO/rGO NCs kill cancer cells through oxidative stress pathway. Moreover, biocompatibility of SnO2-ZnO/rGO NCs was also higher against normal breast epithelial (MCF10A cells) in comparison to SnO2-ZnO NPs and ZnO NPs.

CONCLUSION

SnO2-ZnO/rGO NCs showed enhanced anticancer activity and better biocompatibility than SnO2-ZnO NPs and pure ZnO NPs. This work suggested a new approach to improve the selectivity and anticancer activity of ZnO NPs. Studies on antitumor activity of SnO2-ZnO/rGO NCs in animal models are further warranted.

The Advances of Ceria Nanoparticles for Biomedical Applications in Orthopaedics

The ongoing biomedical nanotechnology has intrigued increasingly intense interests in cerium oxide nanoparticles, ceria nanoparticles or nano-ceria (CeO2-NPs). Their remarkable vacancy-oxygen defect (VO) facilitates the redox process and catalytic activity. The verification has illustrated that CeO2-NPs, a nanozyme based on inorganic nanoparticles, can achieve the anti-inflammatory effect, cancer resistance, and angiogenesis. Also, they can well complement other materials in tissue engineering (TE). Pertinent to the properties of CeO2-NPs and the pragmatic biosynthesis methods, this review will emphasize the recent application of CeO2-NPs to orthopedic biomedicine, in particular, the bone tissue engineering (BTE). The presentation, assessment, and outlook of the orthopedic potential and shortcomings of CeO2-NPs in this review expect to provide reference values for the future research and development of therapeutic agents based on CeO2-NPs.

Reduced graphene oxide mitigates cadmium-induced cytotoxicity and oxidative stress in HepG2 cells

Numerous applications of reduced graphene oxide (RGO) and pervasive cadmium (Cd) have led concern about their co-exposure to the environment and human. We studied the combined effects of RGO and Cd in human liver (HepG2) cells. Initially, we found that RGO (up to 50 μg/ml) did not harm to HepG2 cells while Cd induced dose-dependent (1-10 μg/ml) cytotoxicity. Exciting observations were that a non-cytotoxic concentration of RGO (25 μg/ml) effectively mitigates the toxic effects of Cd (2 μg/ml) such as cell viability reduction, lactate dehydrogenase release, and irregular cell morphology. Cd-induced cell cycle arrest, induction of caspases (3 and 9) enzymes activity, and loss of mitochondrial membrane potential were also significantly alleviated by RGO co-exposure. Moreover, generation of pro-oxidants (reactive oxygen species and hydrogen peroxide levels) and depletion of antioxidants (glutathione level and superoxide dismutase activity) due to Cd exposure was effectively attenuated by RGO co-exposure. Mitigating effect of RGO could be due to strong adsorption of Cd on the large surface area of RGO sheets, which decrease the cellular uptake and bioavailability of Cd for HepG2 cells. This study warrants future research on potential mechanisms of mitigating effects of RGO against Cd-induced toxicity in animal models.

Amination of Graphene Oxide Leads to Increased Cytotoxicity in Hepatocellular Carcinoma Cells

Clinically, there is an urgent need to identify new therapeutic strategies for selectively treating cancer cells. One of the directions in this research is the development of biocompatible therapeutics that selectively target cancer cells. Here, we show that novel aminated graphene oxide (haGO-NH2) nanoparticles demonstrate increased toxicity towards human hepatocellular cancer cells compared to pristine graphene oxide(GO). The applied novel strategy for amination leads to a decrease in the size of haGO-NH2 and their zeta potential, thus, assuring easier penetration through the cell membrane. After characterization of the biological activities of pristine and aminated GO, we have demonstrated strong cytotoxicity of haGO-NH2 toward hepatic cancer cells - HepG2 cell line, in a dose-dependent manner. We have presented evidence that the cytotoxic effects of haGO-NH2 on hepatic cancer cells were due to cell membrane damage, mitochondrial dysfunction and increased reactive oxygen species (ROS) production. Intrinsically, our current study provides new rationale for exploiting aminated graphene oxide as an anticancer therapeutic.

Alleviating effects of reduced graphene oxide against lead-induced cytotoxicity and oxidative stress in human alveolar epithelial (A549) cells

Broad application of reduced graphene oxide (rGO) and ubiquitous lead (Pb) pollution may increase the possibility of combined exposure of humans. Information on the combined effects of rGO and Pb in human cells is scarce. This work was designed to explore the potential effects of rGO on Pb-induced toxicity in human alveolar epithelial (A549) cells. Prepared rGO was polycrystalline in nature. The formation of a few layers of visible creases and silky morphology due to high aspect ratio was confirmed. Low level (25 μg/mL) of rGO was not toxic to A549 cells. However, Pb exposure (25 μg/mL) induced cell viability reduction, lactate dehydrogenase enzyme leakage with rounded morphology in A549 cells. Remarkably, Pb-induced cytotoxicity was significantly mitigated by rGO co-exposure. Pb-induced mitochondrial membrane potential loss, cell cycle arrest and higher activity of caspase-3 and -9 enzymes were also alleviated by rGO co-exposure. Moreover, we observed that Pb exposure causes generation of pro-oxidants (e.g., reactive oxygen species, hydrogen peroxide and lipid peroxidation) and antioxidant depletion (e.g., glutathione and antioxidant enzymes). In addition, the effects of Pb on pro-oxidant and antioxidant markers were significantly reverted by GO co-exposure. Inductively coupled plasma-mass spectrometry suggested that due to the adsorption of Pb on rGO sheets, accessibility of Pb ions for A549 cells was limited. Hence, rGO reduced the toxicity of Pb in A549 cells. This research warrants further study to work on detailed underlying mechanisms of the mitigating effects of rGO against Pb-induced toxicity on a molecular level.

High Surface Reactivity and Biocompatibility of Y2O3 NPs in Human MCF-7 Epithelial and HT-1080 FibroBlast Cells

This study aimed to generate a comparative data on biological response of yttrium oxide nanoparticles (Y₂O₃ NPs) with the antioxidant CeO₂ NPs and pro-oxidant ZnO NPs. Sizes of Y₂O₃ NPs were found to be in the range of 35±10 nm as measured by TEM and were larger from its hydrodynamic sizes in water (1004 ± 134 nm), PBS (3373 ± 249 nm), serum free culture media (1735 ± 305 nm) and complete culture media (542 ± 108 nm). Surface reactivity of Y₂O₃ NPs with bovine serum albumin (BSA) was found significantly higher than for CeO₂ and ZnO NPs. The displacement studies clearly suggested that adsorption to either BSA, filtered serum or serum free media was quite stable, and was dependent on whichever component interacted first with the Y₂O₃ NPs. Enzyme mimetic activity, like that of CeO₂ NPs, was not detected for the NPs of Y₂O₃ or ZnO. Cell viability measured by MTT and neutral red uptake (NRU) assays suggested Y₂O₃ NPs were not toxic in human breast carcinoma MCF-7 and fibroblast HT-1080 cells up to the concentration of 200 μg/mL for a 24 h treatment period. Oxidative stress markers suggested Y₂O₃ NPs to be tolerably non-oxidative and biocompatible. Moreover, mitochondrial potential determined by JC-1 as well as lysosomal activity determined by lysotracker (LTR) remained un-affected and intact due to Y₂O₃ and CeO₂ NPs whereas, as expected, were significantly induced by ZnO NPs. Hoechst-PI dual staining clearly suggested apoptotic potential of only ZnO NPs. With high surface reactivity and biocompatibility, NPs of Y₂O₃ could be a promising agent in the field of nanomedicine.

Self-assembled reduced graphene oxide–cerium oxide nanocomposite@cytochromechydrogel as a solid electrochemical reactive oxygen species detection platform

A new dimension for the selective detection of short-lived ROS by an electroactive reduced graphene oxide–cerium oxide nanocomposite@cytochromechydrogel.