Different Concentrations Of Graphene Oxide Research Articles

Promotion effect of graphene on phytoremediation of Cd-contaminated soil.

Echinacea purpurea (L.) Moench was selected as a remediation plant in this study, and different concentrations of graphene oxide (GO) were added to Cd-contaminated soil. Through pot experiments, the effect of E. purpurea on Cd-contaminated soil was determined at 60 days, 120 days, and 150 days. A preliminary study on the remediation mechanism of GO was explored through changes in the forms of Cd in the rhizosphere soil, soil pH, and soil functional groups. Results showed that the optimal concentration of GO was 0.4 g/kg, and under the condition, the accumulation of Cd in the roots of E. purpurea was as high as 113.69 ± 23.86 mg/kg, and the maximum EF reached 5.87 ± 1.34. Compared with those of the control group, accumulated Cd concentration and EF in the roots increased by 60.34% and 2.32, respectively. Correlation analysis showed that the absorption and accumulation of Cd was negatively correlated with the exchangeable Cd content at 120 days, and the exchangeable Cd was negatively correlated with the relative content of functional groups in the soil with 0.4 g/kg GO (E2). The artificial application of GO to the soil can be used as an effective way to improve the effect of E. purpurea in the remediation of Cd soil pollution, and it has great application potential in the stabilization of plants and vegetations and restoration of high-concentration Cd-contaminated soil.

Graphene oxide leads to mitochondrial-dependent apoptosis by activating ROS-p53-mPTP pathway in intestinal cells.

Owing to its unique physical and chemical properties, graphene oxide (GO) has a wide range of applications in biomedical field. However, with the gradual improvement of biosafety investigations on nanomaterials, growing literatures have pointed out that GO could lead to oxidative stress, aggravation of inflammatory responses, and even irreversible lesions in human multi-tissues, while its damage to small intestinal remained unclear. In this study, we conducted an in-depth study on the toxicological effect of GO on intestinal tissues, and further clarified its toxic effect and molecular mechanism on inducing intestinal cell death. Firstly, we characterized the shape size, potential value, Fourier Transform infrared spectroscopy (FT-IR) characterization and pro-oxidant properties of GO nanosheets. The cytotoxicity of different concentrations of GO to Caco-2 and IEC-6 cell lines was thereafter observed, which was specifically manifested as invoking NADPH Oxidase 1 (NOX1) proteins, accompanied generation of reactive oxygen species (ROS). Since that, more p53 flowed into mitochondria to combine with cyclophilin D (CYPD), thus induced mitochondrial permeability transition pore (mPTP) opening. Through ROS-CyPD-mPTP signaling pathway, GO exerted imbalance of mitochondrial homeostasis, while released cytochrome c (CytC) would ultimate caspase-dependent cell apoptosis. In vivo experiment also confirmed that the microstructure of small intestine was damaged, and the apoptosis rate and oxidative markers were significantly increased in GO-treated Sprague- Dawley (SD) rats (40mg/kg once every other day from day 1 to day 9 by oral gavage). Based on these findings, we conclude that the adverse effects of oral exposure of GO on the biological system mainly concentrate in the digestive tract, and clarify the key role of ROS-mitochondrial homeostasis-apoptosis axis in GO-derived intestinal toxicity. Considering all these results and the fact that GO exhibited intestinal toxicity, we believe that this research providing a safety reference for its biomedical applications.

Research on enhancing the mechanical strength of polyvinyl alcohol/sodium alginate gel beads applied in biological wastewater treatment

This study investigated a new type of polyvinyl alcohol-sodium alginate (PVA/SA) gel beads for immobilization of activated sludge biomass. Gel beads are made from PVA, SA, and graphene oxide (GO) with different concentrations of GO (0.02, 0.2; 2; 20 and 200 mg/L). The results showed that the basic properties, including the roundness and expansion rate of the gel beads, did not differ significantly between the GO concentrations. At the same time, the higher the concentration of go, the more it improves the mechanical strength of the gel beads. The highest strength was when GO levels reached 200 mg/L. At the same concentration, the gel beads achieved the highest methylene blue absorption capacity (91.2%) and the fastest oxygen consumption rate (0.31 mg/L/min) compared to PVA/SA gel beads without GO. This result initially demonstrated that the addition of GO is an effective way to enhance the mechanical strength of PVA/SA gel beads.

Effect of graphene oxide as cryoprotectant on post-thaw sperm functional and kinetic parameters of cross bred (HF X Sahiwal) and Murrah buffalo (Bubalus bubalis) bulls

Graphene oxide (GO) greatly suppresses the growth and recrystallization by curving the hexagonal shape of ice crystals. Study was conducted to evaluate effect of GO as cryoprotectant in semen extender for augmenting sperm viability in dairy (cattle and buffalo) animals. In experiment one, semen was extended with TRIS Egg Yolk Glycerol (TEYG) extender supplemented with different concentrations of GO: 0.0125, 0.25, 0.5, 0.1 and 0.2 mg ml−1. Freezing of semen samples was conducted at 30 °C min−1 from temperature drop from 4 °C to −15 °C and −15 °C to – 60 °C followed by 50 °C min−1 from – 60 °C to −140 °C, and the semen straws were plunged in liquid nitrogen. Second experiment evaluated the performance of TEYG extender supplemented with combinations of GO (G05 as 0.05 and G10 as 0.1 mg ml−1) and glycerol (T48 as 4.8 and T64 as 6.4%) in four groups as G05T48, G05T64, G10T48 and G10T64. Freezing rates of 30 °C min-1[Protocol (PRT) I], 40 °C min−1 (PRT II) and 50 °C min−1 (PRT III) in the critical temperature fall zone of −15 °C to −60 °C were evaluated for semen extender supplemented with glycerol 6.4% and GO 0.05 mg ml−1 in the third experiment. Cattle (n = 3) and buffalo (n = 3) bulls were chosen for the study taking six ejaculates per bull per treatment. Post-thaw sperm motility, membrane integrity, viability and abnormalities were observed by means of CASA, Hypo-osmotic swelling test (HOST), Eosin-Nigrosin stain and Rose Bengal stain procedures, respectively. Post-thaw total motility (TM), progressive motility (PM), VCL, VSL, VAP, HOST response and viability increased significantly in extender with GO concentrations of 0.1 and 0.05 mg ml−1 as compared to control. Per cent abnormalities were significantly (p < .05) lower in group with GO 0.025 and 0.0125 mg ml−1 as compared to control. Results from the second experiment showed higher post-thaw TM, PM, VCL, VAP, VSL, HOST response, viability increased significantly (p < .05) in G05T64 and G05T48 as compared to G10T64. Sperm abnormalities did not vary among the groups as compared to control for cattle spermatozoa. In the third experiment post-thaw TM, PM, VCL, VSL, VAP, HOS response and sperm viability increased significantly (p < .05) in PRT III as compared to PRT I for buffalo and cattle spermatozoa. Sperm abnormalities were significantly (p < .05) lower in PRT II and PRT III as compared to PRT I for buffalo, whereas, lower in PRT II as compared to PRTI for cattle spermatozoa. GO as cryoprotectant when added to semen extender at the rate of 0.05 and 0.1 mg ml−1, resulted in better plasma membrane function and viability. Glycerol concentration below 6.4% in buffalo semen extender reduced post-thaw quality of sperm even when GO was added to the extender. Higher freezing rate of 50 °C min−1 in the critical temperature fall zone of −15 to −60 °C perform better than the freezing rate of 30 °C min−1. It is concluded that TEYG extender having glycerol 6.4% and GO 0.05 mg ml−1 improved post-thaw semen quality of cattle and buffalo.

Graphene oxide chronic exposure enhanced perfluorooctane sulfonate mediated toxicity through oxidative stress generation in freshwater clam Corbicula fluminea

Graphene oxide (GO), a frequently utilized graphene family nanomaterial, is inevitably released into the aquatic environment and interacts with organic pollutants, including perfluorooctane sulfonate (PFOS), a well-known persistent organic pollutant. To determine the adverse effects of GO chronic exposure on PFOS bioaccumulation and toxicity, adult freshwater bivalves, namely Asian clams (Corbicula fluminea) were treated for 28 days with PFOS (500 ng/L) and different concentrations of GO (0.2, 1, 5 mg/L) as PFOS single and GO single exposure groups, as well as PFOS-GO mixture exposure groups. Our results demonstrated that the bioaccumulation of PFOS was significantly enhanced by co-exposure in gills and visceral masses, which was 1.64–2.91 times higher in gills than in visceral masses. Both single, as well as co-exposure, caused a significant reduction in clams’ siphoning behavior, compared to the controls. Further, the co-exposure significantly increased the production of reactive oxygen species (ROS), exacerbating malondialdehyde (MDA) content, enhancing superoxide dismutase (SOD) and catalase (CAT), while decreasing glutathione reductase (GR) and glutathione S-transferase (GST) enzymatic activities in clam tissues. And co-exposure significantly altered the expressions of se-gpx, sod, cyp30, hsp40, and hsp22 genes (associated with oxidative stress and xenobiotic metabolism) both in gills and visceral masses. Moreover, co-exposure caused significant histopathological changes such as cilia degradation in the gills, expansion of tubule lumens in digestive glands, and oocyte shrinkage in gonads. Finally, the enhanced integrated biomarker response (EIBR) index revealed that co-exposure to 500 ng/L PFOS + 1 mg/L/5 mg/L GO was the most stressful circumstance. Overall, our findings suggested that the presence of GO increased PFOS bioaccumulation in tissues, inducing multifaceted negative implications at molecular and behavioral levels through oxidative stress generation in Asian clams.

Assessment on the treatment of nitrogen contaminant by constructed wetland exposed to different concentrations of graphene oxide

The environmental effect of two-dimensional carbon-based graphene oxide (GO) is an emerging worry as it becomes more widely used. The present work investigated the effects of GO (0.5 and 5 mg/L) on nitrogen transformation in constructed wetlands (CWs). GO could be effectively captured by CWs, but it was harmful to nitrogen removal. GO delayed dynamic time of nitrogen transformation with slight increases in ammonia and nitrate effluent concentrations, resulting in nitrogen removal reducing from 59.24% to 51.51–54.12% (p < 0.05). GO showed the selective influence on key enzyme involved in nitrogen transformation. It caused 33% and 37% inhibitions on ammonia monooxygenase (at 0.5 and 5 mg/L GO) and nitrate reductase (only at 0.5 mg/L GO), but 153% stimulations on urease at 5 mg/L GO. The evidence at molecular level showed that GO reduced abundances of amoA, anammox, and nirS gene, which was determined by GO concentration, contact time, and target gene. 5 mg/L GO produced more obvious reductions on relative abundances of denitrification genes (narG, napA, nirK, qnorB, and nosZ) after 120 days. The shifts in microbes related to nitrogen transformation were also observed after GO feeding, but collaborative microbial pathways were still presented including ammonia-oxidizing bacteria (Nitrosomonas and Nitrosospira), nitrite-oxidizing bacteria (Nitrospira), denitrifying bacteria (Sphingomonas, Arenimonas, Rhodopseudomonas, Rhodanobacter), heterotrophic nitrification aerobic denitrification bacteria (Bacillus, Acidovorax, Dechloromonas, Acidovorax), and nitrogen-fixing bacteria. The denitrification was rate-limiting TN removal process due to insufficient carbon sources and dominant aerobic environment in CWs. The present work deepened understanding of variations in ecological functions of CWs when they encountered nano-pollution.

UVA and solar driven photocatalysis with rGO/TiO2/polysiloxane for inactivation of pathogens in recirculation aquaculture systems (RAS) streams

In this study TiO2/polysiloxane(SiBi) thin films modified with different concentrations of graphene oxide (GO) were prepared by ink-jet printing on flexible polyethylene terephthalate (PET) substrates. Prepared coatings were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Raman and water contact angle measurements. During photocatalytic tests strong change of color of prepared coatings modified with GO was observed. XPS analysis of thin films after photocatalytic tests suggests that reduction of GO took place. Prepared coatings were studied for inactivation of microorganisms naturally occurring in aquaculture water under UVA and natural solar irradiation. Effect of rGO concentration in prepared coating on inactivation of target bacteria Aeromonas hydrophila and Citrobacter gillenii was evaluated under UVA irradiation. Aeromonas hydrophila was more sensitive to photocatalytic inactivation in comparison with Citrobacter gillenii. Higher photocatalytic inactivation of target microorganisms was attributed to thin films with concentration of rGO 1 and 5%. The rGO/TiO2/SiBi 5% were further tested for inactivation of Aeromonas salmocida, Serratia fonticola strain and Lactococcus lactis strain under natural solar light. Solar photocatalysis slightly enhanced inactivation of Aeromonas salmocida and Serratia fonticola strain, while opposite was observed for Lactococcus lactis strain.

Effect of graphene oxide wrapped functional silicon carbide on structural, surface protection, water repellent, and mechanical properties of epoxy matrix for automotive structural components

This study is aimed to develop novel nanocomposites with enhanced structural, mechanical and electrochemical properties for automotive applications. Polymeric coatings have been widely used in the automobile industry for the corrosion protection of metallic materials. The (3-aminopropyl)trimethoxysilane (APTMS) functionalized SiC was encapsulated by graphene oxide (GO) as an effective nanofiller in the epoxy matrix (EP). The protective performance of epoxy coating on mild steel in the presence of different concentrations of graphene oxide wrapped silicon carbide nanoparticles was evaluated in seawater by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM). The optimum percentage of graphene oxide embedded SiC nanoparticles in the epoxy matrix was found to be 2.0 wt% in which the coating has the least agglomeration and appropriate corrosion resistance. The EIS measurements showed an enhanced coating resistance of EP-GO/APTMS-SiC nanocomposite (6498.17 kΏ.cm2) after 720 h immersion in seawater compared to EP-SiC (1124.95 kΏ.cm2) and plain epoxy (1.21 kΏ.cm2) coatings. It was found that the coating resistance of the EP-GO/APTMS-SiC nanocomposite coating was around 31% higher than that of the EP matrix. SECM measurements confirmed that the least dissipation of ferrous ions were observed at the crack of the EP-GO/APTMS-SiC nanocomposite coated steel specimen (1.6 I/nA) due to the improved resistance for anodic dissipation of the coated substrate. FE-SEM/EDX examined that Si was reinforced in the degradation products which formed an excellent passive layer at the coating/steel interface. The results showed that the newly developed EP-GO/APTMS-SiC nanocomposite coating possessed superior corrosion protection and enhanced hydrophobic behaviors (WCA: 131º). Therefore, it was concluded that the EP-GO/APTMS-SiC coatings on mild steel displayed superior surface protection, water repellent, and mechanical behaviors in the marine environment for long periods of exposure. Thus, EP-GO/APTMS-SiC coatings on mild steel can be used in industrial and marine applications.

Investigation on low temperature photoluminescence properties of GO-ZnO composite for UV detection application

The effects of different concentrations of graphene oxide (GO) on the optical properties of ZnO particles (Ps) were investigated. A novel sol-gel method was utilized to synthesis ZnO nanopowder as pure and in the presence of different surfactants zinc acetate dihydrate (Zn (CH3COO)2,2H2O), sodium hydroxide (NaOH), Methanol (CH3OH) at calcination temperature 400 °C. The decrease in crystallite size above 11 pH level is evidence of the acceleration of ZnO dissolution during competitive GO-ZnO composite formation. GO-ZnO composite was investigated by low-temperature photoluminescence spectroscopy (PL), we achieved the bandgap shift to 90 meV.

Individual and histopathological responses of the earthworm (Eisenia fetida) to graphene oxide exposure

The increasing production and applications of graphene oxide (GO) inevitably lead to its entry into the environment. However, its potential toxicity to soil invertebrates is not yet completely known. Herein, the harmful effects of GO on the growth, survival, reproduction, and ultrastructure of earthworms were thoroughly evaluated through acute and chronic toxicity experiments. In the acute toxicity experiments, earthworms were exposed to different concentrations of GO using two test methods: filter paper contact test and natural soil contact test. The lethal concentrations (LC50) for GO at 24-h and 48-h exposure were 2.52 and 2.36 mg mL-1, respectively, in the filter paper contact test and the LC50 on day 14 was 68.8 g kg-1 in the natural soil test. Histopathological observation demonstrated that serious skin and intestinal damage occurred with increasing GO concentrations. In the chronic toxicity test, earthworm growth rate and reproduction were investigated after exposure to 0, 5, 10, 20 and 30 g kg-1 GO in natural soil for 28 and 56 d. Earthworm growth was significantly inhibited after 7, 14, 21 and 28 d of GO exposure. The effect was more significant with increasing GO concentrations and exposure days. Moreover, GO exposure significantly decreased the reproductive capacity of earthworms. When earthworms were exposed to 20 g kg-1 GO for 56 d, the number and hatching rate of cocoons and the number of juveniles decreased by approximately half compared with the control. These findings indicate the potential health risk of GO to E. fetida under high concentrations and long exposure times in soil. Thus, the potential risks associated with the application of GO should receive considerable attention. This study can provide valuable information for assessing the toxicity of carbon nanomaterials in terrestrial ecosystems.

Ce-Containing MgAl-Layered Double Hydroxide-Graphene Oxide Hybrid Materials as Multifunctional Catalysts for Organic Transformations.

The combination of layered double hydroxides (LDH) with graphene oxide (GO) enables the formation of nanohybrids with improved properties. This work focuses on the structural and catalytic properties of Ce-containing MgAl LDH-GO composites bearing different concentrations of GO in the range of 5–25 wt.%. The synthesis of the composites was performed by co-precipitating the LDH phase in the presence of GO, while their characterization was performed using XRF, XRD, DRIFT, Raman, SEM, nitrogen adsorption-desorption, and acidity-basicity measurements. The LDH-GO composites, showing redox, basic, and acid catalytic functions, were tested in two different types of organic transformations: (i) Knoevenagel condensation and (ii) one-pot cascade oxidation-Knoevenagel condensation. (i) The cinnamic acid was synthesized by the Knoevenagel condensation of benzaldehyde with diethylmalonate. The composites showed catalytic performances in strong contrast to neat LDH or GO, suggesting a synergistic interaction between the two components. During Knoevenagel condensation, the catalytic activity increased with the GO content in the hybrids up to 15 wt.% and decreased afterwards. (ii) 2-Benzoyl-3-phenylacrylonitrile was synthesized by the aerobic oxidation of benzyl alcohol followed by the Knoevenagel condensation with benzoyl acetonitrile using three different non-polar solvents, i.e., toluene, benzene, and mesitylene. The conversion of benzyl alcohol was higher for the hybrid materials compared to the individual components but decreased with the increase of the graphene oxide concentration.

Ethanol Phase Change Actuator Based on Thermally Conductive Material for Fast Cycle Actuation.

Artificial muscle actuator has been devoted to replicate the function of biological muscles, playing an important part of an emerging field at inter-section of bionic, mechanical, and material disciplines. Most of these artificial muscles possess their own unique functionality and irreplaceability, but also have some disadvantages and shortcomings. Among those, phase change type artificial muscles gain particular attentions, owing to the merits of easy processing, convenient controlling, non-toxic and fast-response. Herein, we prepared a silicon/ethanol/(graphene oxide/gold nanoparticles) composite elastic actuator for soft actuation. The functional properties are discussed in terms of microstructure, mechanical properties, thermal imaging and mechanical actuation characteristics, respectively. The added graphene oxide and Au nanoparticles can effectively accelerate the heating rate of material and improve its mechanical properties, thus increasing the vaporization rate of ethanol, which helps to accelerate the deformation rate and enhance the actuation capability. As part of the study, we also tested the performance of composite elastomers containing different concentrations of graphene oxide to identify GO-15 (15 mg of graphene oxide per 7.2 mL of material) flexible actuators as the best composition with a driving force up to 1.68 N.

Prolific approach for the removal of dyes by an effective interaction with polymer matrix using ultrafiltration membrane

The present work reports the effective method for removal of dyes using graphene oxide (GO) and polysulfone (PSf) composite membranes. The membranes were prepared by phase inversion method using PSf with different concentrations of GO ranging from 1% to 4% and polyethylene glycol (PEG 4000 Da) was used as a pore forming agent. The prepared membranes were successfully characterized for their physical and chemical properties, as well as performance ability in terms of dye removal. The presence of GO in the membranes was unambiguously confirmed by ATR–IR spectra and XRD analysis. While pure water flux and rejection studies were carried out using dead–end filtration unit. The rejection experiment was conducted with and without addition of PVA and it was found that, PVA enhanced the rejection up to 100%. Evidently, 2% GO incorporated membrane demonstrated better rejection compared with other membranes. The process is able to remove 100% Methyl Orange, Methylene Blue, Sulfone Black F, Rhodamine 6G and Malachite Green dyes. Effect of pressure, pH, and time duration on filtration is reported and more effect performance was observed. The probable mechanism for separation of organic dyes was predicted. Finally, industrial dye effluents were also subjected for rejection experiment and 58–68% of rejection was observed. The addition of PVA to dye solution was found as an effective interaction method for removal of dyes using membrane technology.

Performance and responses of aerobic granular sludge at different concentrations of graphene oxide after a single administered dose.

To investigate the impact of graphene oxide (GO) under different concentrations (0, 50, 100, 150, and 200mg/L) on aerobic granular sludge (AGS) after a single administered dose, the performance of nitrogen removal, microbial enzymatic activity, extracellular polymeric substances (EPSs), and microbial community structure was analyzed in batch tests. The results showed that the impact of GO concentrations on AGS was dose- and time-dependent. Short-term GO exposure could accelerate the nitrification process of AGS, while relatively concentrations (≥100mg/L) inhibited the process when present for extended periods of time. The microbial enzymatic activity showed similar tendency. The production of lactate dehydrogenase release (LDH) in 200mg/L group was increased 48.04% and EPS contents decreased 30.06% compared to the control group at 30th day and showed that high concentrations of GO have toxic effects on AGS. The microbial bacteria responded differently to the stimulation of different concentrations of GO. PRACTITIONER POINTS: GO affected AGS system performance in concentration- and time-dependent manners. The nitrification rate of AGS increased in the short term and reversed over time. Long-term exposure to high GO concentrations caused toxicity to AGS. Different microorganisms had diverse responses to GO concentrations.

Preparation and investigation of optical properties and photocatalytic activity of SnO2/GO thin films

In this paper, SnO2-pure and SnO2/GO thin films with different concentrations of graphene oxide (0, 1, 2, 3 and 4 g/ml) were synthesized using spin coating method. The synthesized thin films were used to study the structural, morphology, chemical, optical and photocatalytic degradation of Methyl Orange (MO) under UV light irradiation by X-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FESEM), Raman spectroscopy, Ultraviolet–visible spectroscopy and UV light respectively. The XRD results of graphene oxide show that the peak is very sharp with high intensity, which indicates a very good crystallinity of the GO structure. The band gape value of SnO2/GO thin films increase by increasing of GO concentration. Under UV light irradiation, the photocatalytic activity of synthesized samples was measured using Methyl Orange dye. The obtained results indicate that by adding graphene oxide concentration, the photocatalytic activity of the tin oxide thin film increases.

Novel Flyweight Three-Dimensional Self-Assembled Graphene Oxide/Octa(Aminophenyl) Polyhedral Oligomeric Silsesquioxane Hybrid Aerogels

Herein, flyweight organic-inorganic hybrid scaffolds were fabricated by self-assembly and reduction of graphene oxide via covalent reaction of octa(aminophenyl) polyhedral oligomeric silsesquioxane with graphene oxide. Octa(aminophenyl) polyhedral oligomeric silsesquioxane created a decorative coating on the graphene oxide surface. It acts as a nano-crosslinker, especially on the overlapped-zone of graphene oxide platelets to bind them close-fitting. The resulting hybrid hydrogel was transformed into aerogel by the solvent exchange process with liquid carbon dioxide, followed by liquid carbon dioxide supercritical drying. Different concentrations of graphene oxide and octa(aminophenyl) polyhedral oligomeric silsesquioxane were prepared and the structure-property relationship of obtained aerogels is elucidated. The bulk density and porosity of the aerogels are located between the super-low values of 2.7 to 5.9 mg cm-3 and beyond 99.5 %, respectively. According to the adsorption-desorption isotherms of BET-technique, the surface area of obtained aerogels was between 250 to 713 m2/g. The findings remark the potential application of obtained aerogels in the production of supercapacitors, lithium-ion batteries, solar cells, etc. in energy storage and conversion devices, electrode materials, sensors, gas/oil/dye adsorbents, and high-temperature insulators in the aerospace industry.

The Characters of Graphene Oxide Nanoparticles and Doxorubicin Against HCT-116 Colorectal Cancer Cells In Vitro.

Colorectal cancer (CRC) is among the leading causes of cancer death worldwide. Graphene oxide (GO) plus doxorubicin (DOX) have low toxicity and facilitate drug carriage and provide enough surface. The GO-DOX anticancer effects against HCT-116 human CRC cells were compared with that of pure GO and DOX compounds. Different concentrations of graphene oxide (GO), doxorubicin (DOX), and graphene oxide plus doxorubicin (GO-DOX) were prepared. The MTT test was conducted to determine the viability of cells and flow cytometry was performed following DOX, GO, and GO-DOX exposure. Expressions of caspase 3, Bax, and ATG5 autophagy-related genes were investigated using RT-qPCR technique. In the MTT test, DOX and GO at 100µg/mL and 40µg/mL exerted 50% cell death (LC50) against the HCT-116 cells. We observed significant differences in GO-DOX LC50 at concentrations of 1 (p = 0.003), 2.5 (p = 0.003), 5 (p = 0.00009), and 10µg/mL (p = 0.0001). The rate of apoptosis following GO, DOX, and GO-DOX included 24%, 31%, and 56%, respectively. The GO-DOX significantly increased the ATG5 (3.1-fold, p < 0.0001), caspase 3 (4.7-fold, p < 0.0001), and Bax (4.3-fold, p < 0.0001) gene expression. The GO-DOX exerted anticancer effects against the HCT-116 cells via inducing the apoptosis and autophagy.

Growth response of Oryza sativa seedlings to graphene oxide and its variability among genotypes

With the extensive utilization of graphene nanomaterials, they inevitably enter our environment. The potential phytotoxicity and environmental impact of graphene oxide (GO) have recently attracted much attention. We designed the experiment based on seed germination, seedling morphology, physio-biochemical properties, and antioxidant enzyme activities of five rice genotypes (9311, MH63, R527, K866, and Nipponbare) under six concentrations of GO (0, 5, 10, 50, 100, and 150 mg dm-3). We studied the effects of different concentrations of GO on germination index (GI), shoot length (SL) and root length (RL), adventitious root number, shoot and root fresh masses, root/shoot ratio, chlorophyll (Chl) content, malondialdehyde content, and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Graphene oxide treatments significantly enhanced seed germination and root growth and inhibited shoot growth of all genotypes. Furthermore, we found a significant genotype-dependent response to GO treatments. According to the relative increment trend of GI, SL, and RL, root/shoot ratio, antioxidant enzyme activities (CAT, POD, and SOD), and Chl content, 'R527' showed more tolerance to GO treatments than the other four genotypes. The 'MH63' and 'K866' were more sensitive than 'Nipponbare' and '9311'. It indicates that the GO-tolerant genotype might avoid free radicals damage from GO by increased antioxidant enzyme activities. Moreover, we should consider the genotype differences when evaluating the potential phytotoxicity of GO and environmental risk to ecosystems.

Development of Green and Sustainable Cellulose Acetate/Graphene Oxide Nanocomposite Films as Efficient Adsorbents for Wastewater Treatment.

Novel ecofriendly adsorbents, cellulose acetate/graphene oxide (CA-GO) nanocomposite, were prepared from sugarcane bagasse agro-waste for removing Ni2+ ions from wastewater. Graphene oxide (GO) was prepared by the oxidation of sugarcane bagasse using ferrocene under air atmosphere. Cellulose acetate (CA) was also prepared from sugarcane bagasse by extraction of cellulose through a successive treatments with sulfuric acid (10% v/v), sodium hydroxide (5% w/v), ethylenediaminetetraacetic acid, and hydrogen peroxide, and finally, followed by acetylation. CA-GO was prepared via mixing of GO and CA in the presence of calcium carbonate and different concentrations of GO, including 5, 10, 15, 20, 25, and 30 wt% relative to the weight of CA. The CA-GO nanocomposite showed porous microstructures with high surface area, which enhance their ability towars the adsorption of Ni2+ ions from wastewater. The morphological properties of the prepared adsorbents were explored by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The efficiency of the CA-GO towards the adsorption of Ni2+ ions from wastewater was explored against as time, temperature, and total content of Ni2+ ions. The adsorption measurements of Ni2+ ions were investigated within the concentration range of 10–40 mg/L, time range between 15 and 90 min, and temperature range between 25 °C and 55 °C. The results displayed a considerable improvement in the adsorption process of Ni2+ ions by CA-GO-2 with a removal efficiency of 96.77%. The isotherms were monitored to best fit the Langmuir model. Finally, the adsorption performance of the prepared CA-GO nanocomposite films demonstrated promising properties as green, sustainable and cheap adsorbents for water pollutants.

LDH-GO composites as catalysts for the oxidative removal of indigo carmine dye from wastewater

Herein, we present the results of our researches focused on obtaining composites with enhanced affinity for indigo carmine (IC) by combining two different 2D materials e.g. graphene oxide (GO) and a Cerium modified layered double hydroxide (LDH), which could act as catalysts for the oxidative removal of IC, both under ultrasonic irradiation and under conventional stirring, using H2O2 as oxidation agent. Three Mg3Al0.75Ce0.25 LDH-GO composites bearing different concentrations of GO in the range of 5-15 wt.% abbreviated as HT3Ce-xGO where x stands for the concentration of GO (x=5,10,15% wt. GO) have been prepared and characterized by XRD, SEM, Raman and DRIFT spectroscopy. The XRD patterns of HT3Ce-xGO solids have revealed the formation of nanocomposites with fine particles of CeO2 (Scherrer dimensions around 3 nm) embedded in the 2D layered structure of LDH-GO. CeO2 phase was favored by the increase in GO content for all investigated composites. The size decrease of the solid particles with the increase of GO content was proved both by SEM and DRIFT analyses. Raman spectra proved the incorporation of GO in all composites. The results of the catalytic tests showed, without any doubt the activation effect of the ultrasonic irradiation which allowed doubling the dye removal percentage (DR%) in the first 30 minutes of reaction time. For the most active catalyst, HT3Ce-15GO, the COD after 30 minutes reaction time under ultrasonic irradiation was 221 mgO2/L, while TOC was 93 mgC/L marking a decay of 61.6% for COD and 46.2% for TOC.