Graphene Oxide Nanomaterials Research Articles

The impact of graphene oxide sheet lateral dimensions on their pharmacokinetic and tissue distribution profiles in mice

Although the use of graphene and 2-dimensional (2D) materials in biomedicine has been explored for over a decade now, there are still significant knowledge gaps regarding the fate of these materials upon interaction with living systems. Here, the pharmacokinetic profile of graphene oxide (GO) sheets of three different lateral dimensions was studied. The GO materials were functionalized with a PEGylated DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), a radiometal chelating agent for radioisotope attachment for single photon emission computed tomography (SPECT/CT) imaging. Our results revealed that GO materials with three distinct size distributions, large (l-GO-DOTA), small (s-GO-DOTA) and ultra-small (us-GO-DOTA), were sequestered by the spleen and liver. Significant accumulation of the large material (l-GO-DOTA) in the lungs was also observed, unlike the other two materials. Interestingly, there was extensive urinary excretion of all three GO nanomaterials indicating that urinary excretion of these structures was not affected by lateral dimensions. Comparing with previous studies, we believe that the thickness of layered nanomaterials is the predominant factor that governs their excretion rather than lateral size. However, the rate of urinary excretion was affected by lateral size, with large GO excreting at slower rates. This study provides better understanding of 2D materials in vivo behaviour with varying structural features.

Polyaza functionalized graphene oxide nanomaterial based sensor for Escherichia coli detection in water matrices

Water quality is widely discussed owing to its significance in public health due to the inability to access clean water. Waterborne diseases account for the presence of pathogens like Escherichia coli (E. coli) in drinking water in the environmental community. Owing to the rapid increase of such bacterial microorganisms, a cost-effective sensor setup has been developed. Herein, we demonstrate the amine-functionalized graphene oxide (fGO) based 2D nanomaterial used to graft E. coli on its surface. The comparative analysis of the deposition of nanosheets on the glass substrate and PDMS was executed. The impedance variations of GO-based nanosensor at various concentrations of E. coli were performed and their potential difference was recorded. It was observed that the impedance changes inversely with the bacterial concentrations and was fed to the Arduino microcontroller. The experimental setup was standardized for the range of 0.01 Hz to 100 kHz. The obtained analog data was programmed with a microcontroller and the bacterial concentration in colony-forming units was displayed. The real-time analysis showsthe low-level detection of E. coli in aquatic environments. Experiments were conducted using the developed nanosensor to test the efficiency in complex water matrices and whose behavior changes with various physical, chemical, and environmental factors.

Enhancing interfacial bonding between epoxy and CSH using graphene oxide: An atomistic investigation

Graphene oxide (GO) is being considered for improving the bonding properties of the epoxy-concrete interface, which is of great significance in enhancing the durability and sustainability of fiber-reinforced polymer (FRP) embedded with concrete structures. Substantial improvement in the bonding performance of epoxy-concrete interface by GO nanomaterial relies heavily on the optimal design of GO-insertion in the interfacial region, and such manipulation requires comprehensive understanding of the interfacial adhesion of the epoxy-concrete interface before and after GO-modification. Herein, the bonding performances of the epoxy-calcium silicate hydrate (CSH) interface with and without the GO-modification are investigated using molecular dynamics simulations. Notably, epoxy adhered to the GO sheet exhibits better resistance to pulling forces than that adhered directly to the CSH surface, which demonstrates bonding improvement after GO-modification. Beyond the hydrogen bonding connections formed between epoxy and oxygen-containing functional groups of GO, the high interactions between epoxy and graphene sheet dominate the excellent performance at the epoxy-GO interface.

Flow and heat transportation in peristalsis of graphene-Fe 3 O 4 /H 2 O hybrid nanofluid with variable effective viscosity

Present communication addresses the flow and heat transportation for peristaltic transport of graphene-Fe 3 O 4/H 2 O hybrid nanofluid with irreversibility rate. Effects of variable viscosity, Hall current, Joule heating, porous medium and mixed convection are considered. A hybrid nanomaterial system is prepared by dispersing graphene and iron oxide nanomaterials with mass ratio (2:1) in an aqueous solution (water). Convective boundary conditions for temperature are also employed. The mathematical model is simplified by using lubrication theory. The obtained dimensionless model is then numerically solved. Results reveal that temperature of hybrid nanofluid reduces with an enhancement in volume fraction of graphene nanomaterials. Heat transfer rate at the right wall decays by increasing viscosity parameter. Velocity profile increases for larger permeability and Hall parameters. Presence of graphene nanomaterials decreases the pressure gradient. Entropy generation and Bejan numbers decrease by enhancing Biot number. The thermal efficiency of hybrid nanofluid (graphene-Fe 3 O 4/H 2 O) is more pronounced as compared to ordinary nanofluid (Fe 3 O 4/H 2 O) and base fluid (H 2 O). Additionally, comparison between NDSolve and numerical results achieved with bvp4c in MATLAB is also carried out to test our numerical codes.

The Influence of Temperature Increase on the Toxicity of Mercury Remediated Seawater Using the Nanomaterial Graphene Oxide on the Mussel Mytilus galloprovincialis

Mercury (Hg) has been increasing in waters, sediments, soils and air, as a result of natural events and anthropogenic activities. In aquatic environments, especially marine systems (estuaries and lagoons), Hg is easily bioavailable and accumulated by aquatic wildlife, namely bivalves, due to their lifestyle characteristics (sedentary and filter-feeding behavior). In recent years, different approaches have been developed with the objective of removing metal(loid)s from the water, including the employment of nanomaterials. However, coastal systems and marine organisms are not exclusively challenged by pollutants but also by climate changes such as progressive temperature increment. Therefore, the present study aimed to (i) evaluate the toxicity of remediated seawater, previously contaminated by Hg (50 mg/L) and decontaminated by the use of graphene-based nanomaterials (graphene oxide (GO) functionalized with polyethyleneimine, 10 mg/L), towards the mussel Mytilus galloprovincialis; (ii) assess the influence of temperature on the toxicity of decontaminated seawater. For this, alterations observed in mussels’ metabolic capacity, oxidative and neurotoxic status, as well as histopathological injuries in gills and digestive tubules were measured. This study demonstrated that mussels exposed to Hg contaminated seawater presented higher impacts than organisms under remediated seawater. When comparing the impacts at 21 °C (present study) and 17 °C (previously published data), organisms exposed to remediated seawater at a higher temperature presented higher injuries than organisms at 17 °C. These results indicate that predicted warming conditions may negatively affect effective remediation processes, with the increasing of temperature being responsible for changes in organisms’ sensitivity to pollutants or increasing pollutants toxicity.

Fabrication and Characterization of Sulfonated Graphene Oxide-Doped Polymeric Membranes with Improved Anti-Biofouling Behavior

In this study, cellulose acetate (CA) was blended with sulfonated graphene oxide (SGO) nanomaterials to endow a nanocomposite membrane for wastewater treatment with improved hydrophilicity and anti-biofouling behavior. The phase inversion method was employed for membrane fabrication using tetrahydrofuran (THF) as the solvent. The characteristics of CA-SGO-doped membranes were investigated through thermal analysis, contact angle, SEM, FTIR, and anti-biofouling property. Results indicated that anti-biofouling property and hydrophilicity of CA-SGO nanocomposite membranes were enhanced with addition of hydrophilic SGO nanomaterials in comparison to pristine CA membrane. FTIR analysis confirmed the successful decoration of SGO groups on CA membrane surface while revealing its morphological properties through SEM analysis. Thermal analysis performed using DSC confirmed the increase in thermal stability of CA-SGO membranes with addition of SGO content than pure CA membrane.

Facile fabrication of hierarchically porous graphene/poly(1,5-diaminoanthraquinone) nanocomposite fibers as flexible and robust free-standing electrodes for solid-state supercapacitors

BackgroundFiber-shaped supercapacitors have attracted more and more interests for portable/wearable electronics. However, the practical application is suffering from their tedious fabrication and limited electrochemical performance. MethodsHere, hierarchically porous graphene/poly(1,5-diaminoanthraquinone) nanocomposite (ErGO/PDAA) fibers were fabricated as flexible and robust free-standing electrodes for supercapacitors, via facile coagulation of expanded graphene oxide (EGO) and PDAA nanomaterials with different morphologies, such as nanoparticles (PNPs), nanotubes (PNTs), and nanoribbons (PNRs), in CaCl2 bath, followed by reduction with hydroiodic acid (HI). Significant findingsAll the three ErGO/PDAA fibers showed distinctly enhanced electrochemical property than the ErGO fiber. Furthermore, with the same feeding ratio of EGO and PDAA (6:4), the ErGO/PNTs fiber possessed better electrochemical capacitive property than the other two, ErGO/PNPs and ErGO/PNRs fibers, owing to the unique hierarchical pores. The solid-state symmetric supercapacitor (SSC) possessed specific capacitance, energy and power densities of 35.0 mF cm−1, 3.11 mWh cm−1, and 61.4 mW cm−1, respectively, and retained 83.3% of its initial capacitance after 5000 cycles.

Evaluation of antibacterial behavior of in situ grown CuO-GO nanocomposites

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD) results showed that CuO and GO synthesized were free of impurities and unwanted phases. Fourier Transform Infrared Spectroscopy (FTIR) spectrum of the prepared sample has revealed the presence of vibrational modes related to Cu-O, alkoxy group (O-H), epoxy group (C-O-C), and carboxyl group (C-O). In Raman spectroscopy, the CuO nanostructure has a redshift, and in the CuO-GO nanocomposite, D band and G band have blueshift and redshift by increasing the amount of GO, respectively. The results of UV-Vis spectra showed that synthesized CuO and GO have a higher band gap (4.54 eV and 3.03 eV, respectively) than previous studies. Also, the highest amount of band gap of nanocomposites is related to the 50%wt GO nanocomposite (3.40 eV). Field emission scanning electron microscope (FESEM) images showed that CuO nanosheets bonded with GO plates and decorated the GO plates. Antibacterial activity of synthesized nanocomposite investigated using Escherichia coli (E.coli) bacteria. The antibacterial test results showed that CuO nanoparticles have inadequate antibacterial activity (15%), while by composting with GO, the antibacterial activity against E. coli significantly increased (for 50% GO about 76%). However, the antibacterial activity reduced to 68% for the nanocomposite sample with 75% GO concentration; thus, 50% GO nanocomposite is the optimal concentration.

Investigation of Hybrid Methods for Elimination of Brilliant Blue Dye from Water Phase Using Various Nanomaterials Combined with Activated Sludge and Duckweed.

The main goal of this experimental work is screening of different natural and synthetic nanomaterials and biopolymers that may improve elimination of stable micropollutants from water phase. In this work, as a target chemical acting as the micropollutant molecule, the Brilliant Blue (BB) dye was selected. We tested different active matrices dispersed in water phase including activated carbon (AC), lyophilized graphene oxide (GO), β-cyclodextrin (CD), raw dandelion pappus (DP), microcrystalline cellulose(MC), and raw pine pollen (PP), as well as two types of Egyptian Blue mineral pigments (EB1 and EB2). Graphene oxide and Egyptian Blue nanomaterials were synthesized in our laboratory. We investigated potential application of such nanoparticles and biopolymer conglomerates as additives that may tune the activated sludge (AS) microorganisms or duckweed water plant (DW) and increase efficiency of micropollutants removal from wastewater. Studied nanomaterials/biopolymers were used in two different experimental modes involving real activated sludge microorganisms (24 h experiment) as well as duckweed plant (16 day experiment). Quantitative data of BB were obtained using microfluidic type device based on micro-TLC plate. This approach enabled direct determination of target component without sample pre-treatment like pre-concentration or pre-purification. Within single analytical run calibration line, retention standard spots (methyl red) and multiple samples were analyzed simultaneously. Due to the multivariate nature of these experiments, quantitative data were explored with chemometric tools including AHC (agglomerative hierarchical clustering), PCA (principal component analysis), and FA (factor analysis). Experimental data and multivariate calculations revealed that BB is strongly resistant on biodegradation, however, inclusion complexes formation with β-cyclodextrinmay induce degradation of this dye in the presence of duckweed. It is hoped that results of our experimental work can be used for designing of future experiments for fast screening of different additives and improvement of technological processes, focusing on purification of sewage and water from micropollutants.

Tribological synergies among chemical-modified graphene oxide nanomaterials and a phosphonium ionic liquid as additives of a biolubricant

In the present work, antifriction and antiwear synergies of two functionalized graphene oxides (reduced graphene oxide, rGO, and reduced graphene oxide modified with octadecylamine, rGO@ODA) with a phosphonium ionic liquid (IL) as additives of a biodegradable ester base oil, BIOE, were investigated. For this aim, four BIOE nanodispersions were formulated: two nanodispersions without IL and two others with IL (hybrid nanolubricants), being the nanodispersions: BIOE + 0.05 wt% rGO, BIOE + 0.05 wt% rGO@ODA, BIOE + 1 wt% IL + 0.05 wt% rGO and BIOE + 1 wt% IL + 0.05 wt% rGO@ODA, and all of them showing good temporal stability (at least 3 weeks), especially those containing the ionic liquid. Tribological tests, under pure sliding conditions, were made with the aforementioned nanolubricants and with neat BIOE under a 20 N working load. All hybrid and non-hybrid nanolubricants resulted in lower friction coefficients compared to BIOE oil, with the largest friction reduction of 34% achieved by the 1 wt% IL + 0.05 wt% rGO nanolubricant. Discs lubricated with the prepared nanolubricants showed less wear than discs lubricated with BIOE, achieving the highest reduction (34%) in wear track width also for the 1 wt% IL + 0.05 wt% rGO nanolubricant. In addition, through confocal Raman microscopy, as well as roughness analysis of tested discs, it can be concluded that surface repairing, synergistic effect and tribofilm formation mechanisms occur.

Imprinted polymer and Cu2O-graphene oxide nanocomposite for the detection of disease biomarkers

α 1-Acid glycoprotein (α 1-AGp) is a critical plasma protein that acts as a biomarker for different diseases when produced in large amounts (>1.2 mg ml−1). Therefore, selective, label-free, and fast detection of α 1-AGp in human serum is essential. This article presents the development of selective coatings based on molecularly imprinted polymer (MIP) matrix with boronate-affinity and Cu2O-decorated reduced graphene oxide (Cu2O-rGO) nanomaterials. The MIP-Cu2O-rGO hybrid coatings are fabricated on quartz crystal microbalance (QCM) to develop biomimetic α 1-AGp sensors. The MIP:Cu2O-rGO ratio is optimized to enhance sensing properties. Thus-designed MIP-Cu2O-rGO/QCM sensor performs sensitive and specific detection of α 1-AGp in complex mixtures. The initial assessment of the MIP-Cu2O-rGO/QCM sensor reveals an eight-fold increase in the response toward α 1-AGp compared to non-imprinted polymer. The MIP-Cu2O-rGO/QCM sensor exhibits high sensitivity (16.28 Hz ng−1 ml−1) and a low limit of detection (0.25 ng ml−1). When compared with multiple biorelevant analytes such as bovine serum albumin, lysozyme, glucose, fructose, and uric acid, the sensor shows high selectivity due to suitably oriented imprints or interaction sites that are tailored for α 1-AGp recognition. Furthermore, the MIP-Cu2O-rGO/QCM sensor can effectively detect 150–200 ng ml−1 of α 1-AGp in spiked human serum samples with a recovery rate of ∼92%. The results achieved in this study are compared with the relevant literature. The MIP-Cu2O-rGO/QCM sensor can be suitably used for the label-free, precise detection of α 1-AGp in complex mixtures.

Improved fluoride removal efficiency using novel defluoridation pencil

A facile route to a novel defluoridation prototype was developed i.e. fluoride (F−) pencil enclosing 3D network porous hydrogel structure consisted of 2D Graphene oxide (GO) sheets and nanomaterials. Green synthesized nanomaterials as aluminium oxide (Al2O3), silver oxide (Ag2O), carbon quantum dots (CQDs) with GO were successfully utilized for developed defluoridation pencil. Synthesized graphene-aluminium-silver-carbon quantum dots (GO-Al2O3-Ag2O-CQDs: GAAC) hydrogel showed high adsorption capacity with characterization through analytical techniques such as field emission scanning electron microscope (FESEM), x-ray diffraction (XRD), energy dispersive x-ray analysis (EDX), fourier transform infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (HRTEM). The adsorption capacity of GAAC hydrogel was as high as 12.04 mg g-1. Developed hydrogel exhibited removal percentage for 2 and 10 mg L-1 F− as 95.5 and 80 %, respectively. Kinetically, GAAC material for F− adsorption obeyed pseudo-second-order model (R2 = 0.999) as compared to pseudo-first-order model. Langmuir adsorption isotherm (R2 = 0.978) proved more favourable than Freundlich model (R2 = 0.928), which confirmed chemisorption processes for F− adsorption. Finally, mechanism showed that F− ion uptake and release of −OH groups which are bonded to the GAAC composite on the gels is connected.

Graphene oxide disrupted mitochondrial homeostasis through inducing intracellular redox deviation and autophagy-lysosomal network dysfunction in SH-SY5Y cells

Graphene oxide (GO) nanomaterials have significant advantages for drug delivery and electrode materials in neural science, however, their exposure risks to the central nervous system (CNS) and toxicity concerns are also increased. The current studies of GO-induced neurotoxicity remain still ambiguous, let alone the mechanism of how complicated GO chemistry affects its biological behavior with neural cells. In this study, we characterized the commercially available GO in detail and investigated its biological adverse effects using cultured SH-SY5Y cells. We found that ultrasonic processing in medium changed the oxidation status and surface reactivity on the planar surface of GO due to its hydration activity, causing lipid peroxidation and cell membrane damage. Subsequently, ROS-disrupted mitochondrial homeostasis, resulting from the activation of NOX2 signaling, was observed following GO internalization. The autophagy-lysosomal network was initiated as a defensive reaction to obliterate oxidative damaged mitochondria and foreign nanomaterials, which was ineffective due to reduced lysosomal degradation capacity. These sequential cellular responses exacerbated mitochondrial stress, leading to apoptotic cell death. These data highlight the importance of the structure-related activity of GO on its biological properties and provide an in-depth understanding of how GO-derived cellular redox signaling induces mitochondrion-related cascades that modulate cell functionality and survival.

Eco-Friendly Reduced Graphene Oxide Nanofilter Preparation and Application for Iron Removal

In this paper, the green synthesis of reduced graphene oxide (r-GO) nanomaterials using Callistemon viminalis leaf extract as a reducing and stabilizing agent is reported for the first time. The synthesized r-GO nanomaterials were characterized using UV–Vis, XRD, FE-SEM, TEM, and energy dispersive X-ray (EDX) analyses. The nanofilter membrane was prepared by varying the amounts of r-GO nanomaterials in a Polysulfone-N,N-dimethyl formamide (DMF) solution. The nanofilter membrane was characterized by the contact angle, atomic force microscopy (AFM), UV–Vis, and FTIR. The results confirm the formation of r-GO nanomaterials. Higher amounts of r-GO nanomaterials in the membrane show a lower contact angle, thus confirming their hydrophilic nature. Iron water filtration was performed with different amounts of r-GO nanomaterials in the membrane filter, and the water flux was smooth over an increased time period. Inductively Coupled Plasma (ICP) analysis showed a higher percentage of iron rejection (95.77%) when higher amounts (0.10 g) of r-GO nanomaterials were used in a mixed membrane (i.e., sample C). In conclusion, the findings illustrate that Callistemon viminalis mediates the synthesis of r-GO nanomaterials, which is useful in water filtration, and can be incorporated into membrane filters, since it removes iron.

Reduced graphene oxide as effective adsorbent for removal of heavy metals in groundwater of Amaravathi River basin, Tamil Nadu

ABSTRACT The main aim of the present study was to weigh up and identifies the groundwater quality in the Amaravathi River basin of Karur district. Twenty four samples were collected, processed, and analyzed for various physico-chemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), cation such as calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and potassium (K+); anion such as bicarbonate (HCO3 −), chloride (Cl−), sulphate (SO4 2-), and fluoride (F−) in the laboratory using the standard methods given by the American Public Health Association. Specifically, we investigated trace metals like cadmium (Cd2+), lead (Pb2+), copper (Cu2+), zinc (Zn2+), manganese (Mn2+), nickel (Ni2+), and iron (Fe2+) using Atomic Absorption Spectrophotometer. Out of 24 samples, Thirumanilayur sample is taken for treatment process because all the physico–chemical parameters, and heavy metals Cd2+ and Pb2+ were well above the permissible limits laid by World Health Organizationand Bureau of Indian Standards.Graphene oxide (GO) nanoparticle is taken for treatment process and its adsorption capacity was confirmed by XRD, SEM, FTIR, and EDS techniques. The treated groundwater sample using graphene oxide nanomaterial (60 and 80 mg) show a positive result for reducing the excess metal ions (Cd2+ and Pb2+), in addition to various water quality parameters.

New insights into the colloidal stability of graphene oxide in aquatic environment: Interplays of photoaging and proteins

Wide application leads to release of graphene oxide (GO) in aquatic environment, where it is subjected to photoaging and changes in physicochemical properties. As important component of natural organic matters, proteins may greatly affect the aggregation behaviors of photoaged GO. The effects of a typical model protein (bovine serum albumin, BSA) on the colloidal stability of photoaged GO were firstly investigated. Photoaging reduced the lateral size and oxygen-containing groups of GO, while the graphene domains and hydrophobicity increased as a function of irradiation time (0–24 h). Consequently, the photoaged GO became less stable than the pristine one in electrolyte solutions. Adsorption of BSA on the surface of the photoaged GO decreased as well, leading to thinner BSA coating on the photoaged GO. In the solutions with low concentrations of electrolytes, the aggregation rate constants (k) of all the photoaged GO firstly increased to the maximum agglomeration rate constants (kfast, regime I), maintained at kfast (regime Ⅱ) and then decreased to zero (regime Ⅲ) as the BSA concentration increased. In both regime I and III, the photoaged GO were less stable at the same BSA concentrations, and the impacts of BSA on the colloidal stability of the photoaged GO were less than the pristine one, which was attributed to the weaker interactions between the photoaged GO and BSA. This study provided new insights into the colloidal stability and fate of GO nanomaterials, which are subjected to extensive light irradiation, in wastewater and protein-rich aquatic environment.

Removal of Mn(II) from Acidic Wastewaters Using Graphene Oxide-ZnO Nanocomposites.

Pollution due to acidic and metal-enriched waters affects the quality of surface and groundwater resources, limiting their uses for various purposes. Particularly, manganese pollution has attracted attention due to its impact on human health and its negative effects on ecosystems. Applications of nanomaterials such as graphene oxide (GO) have emerged as potential candidates for removing complex contaminants. In this study, we present the preliminary results of the removal of Mn(II) ions from acidic waters by using GO functionalized with zinc oxide nanoparticles (ZnO). Batch adsorption experiments were performed under two different acidity conditions (pH1 = 5.0 and pH2 = 4.0), in order to evaluate the impact of acid pH on the adsorption capacity. We observed that the adsorption of Mn(II) was independent of the pHPZC value of the nanoadsorbents. The qmax with GO/ZnO nanocomposites was 5.6 mg/g (34.1% removal) at pH = 5.0, while with more acidic conditions (pH = 4.0) it reached 12.6 mg/g (61.2% removal). In turn, the results show that GO/ZnO nanocomposites were more efficient to remove Mn(II) compared with non-functionalized GO under the pH2 condition (pH2 = 4.0). Both Langmuir and Freundlich models fit well with the adsorption process, suggesting that both mechanisms are involved in the removal of Mn(II) with GO and GO/ZnO nanocomposites. Furthermore, adsorption isotherms were efficiently modeled with the pseudo-second-order kinetic model. These results indicate that the removal of Mn(II) by GO/ZnO is strongly influenced by the pH of the solution, and the decoration with ZnO significantly increases the adsorption capacity of Mn(II) ions. These findings can provide valuable information for optimizing the design and configuration of wastewater treatment technologies based on GO nanomaterials for the removal of Mn(II) from natural and industrial waters.

Ecofriendly and enhanced photocatalytic degradation of Indigo dye by graphene oxide nanoparticles

In the present work, photocatalytic degradation of indigo dye by synthesized graphene oxide (GO) nanomaterials using conventional and improved Hummers method has been reported. In the present research, the emphasis is to explore the photocatalytic degradation of GO, using NaNO3 (N-GO) and without using NaNO3 (WN-GO) under the exposure of UV light. WN-GO possesses eco-friendly behaviour as it eliminates the generation of toxic gases (NO2/N2O2) in the atmosphere. Synthesized nanomaterials were characterized using SEM–EDS, XRD, Raman spectroscopy, UV–Vis and FTIR. Indigo dye (C16H10N2O2) was identified as a model to investigate the photocatalytic degradation of GO nanoparticles under UV exposure. The absorbance peak of indigo dye with N-GO and WN-GO has been plotted as a function of irradiation time. The progress of the decolourization reaction of dye with catalysts was measured by a change in colour from blue to transparent. Compared to N-GO, WN-GO possesses organic and eco-friendly degradation of indigo dye under UV irradiation. The versatile photocatalytic characteristics of WN-GO possess higher-order degradation rate constant (k) makes it a potential candidate for bioremediation of wastewater treatment. Therefore, the degradation of indigo dye with GO exhibits encouraging solution for treating contaminated water and provides a facile route towards environmental cleanness.

An experimental study on heat transfer performance of GO and rGO-CuO nanofluids in a heat exchanger

In the present work, we have reported the synthesis and characterization of graphene oxide (GO) and copper oxide functionalized reduced graphene oxide (rGO-CuO) nanomaterials and studied their heat transfer properties. The synthesized materials are characterized using FTIR, XRD, UV–vis spectrophotometry, STM, EDX, SEM, and TEM analysis. Both GO and rGO-CuO nanomaterials are used as water-based NFs to study the heat transfer performance. The maximum enhancement of heat transfer rate and effectiveness of GO-water NF are found to be 18.51% and 24.58% concerning Di-water, respectively. Whereas, in the rGO-CuO-water NFs, maximum enhancement in the heat transfer rate and the effectiveness is obtained as 24.07% and 37%, compared to the Di-water, respectively. The maximum increase in Nusselt number for GO-water NF is found to be 16.48% as compared to Di-water. Whereas, for rGO-CuO-water NF is found to be 23.84% and 6.3% compared to Di-water and GO-water NFs at Reynold numbers 806.67, 1210.48, and 1617.21, respectively. These NFs may be useful in the future for heat exchanger applications.

Indoleamine 2,3-Dioxygenase 1 Inhibitor-Loaded Nanosheets Enhance CAR-T Cell Function in Esophageal Squamous Cell Carcinoma.

In chimeric antigen receptor (CAR)-T cell therapy, the role and mechanism of indoleamine 2, 3 dioxygenase 1 (IDO1) in enhancing antitumor immunity require further study. IDO1 is one of the most important immunosuppressive proteins in esophageal squamous cell carcinoma (ESCC). However, the IDO1 inhibitor, epacadostat, has failed in phase III clinical trials; its limited capacity to inhibit IDO1 expression at tumor sites was regarded as a key reason for clinical failure. In this study, we innovatively loaded the IDO1 inhibitor into hyaluronic acid-modified nanomaterial graphene oxide (HA-GO) and explored its potential efficacy in combination with CAR-T cell therapy. We found that inhibition of the antitumor effect of CAR-T cells in ESCC was dependent on the IDO1 metabolite kynurenine. Kynurenine could suppress CAR-T cell cytokine secretion and cytotoxic activity. Inhibiting IDO1 activity significantly enhanced the antitumor effect of CAR-T cells in vitro and in vivo. Our findings suggested that IDO1 inhibitor-loaded nanosheets could enhance the antitumor effect of CAR-T cells compared with free IDO1 inhibitor. Nanosheet-loading therefore provides a promising approach for improving CAR-T cell therapeutic efficacy in solid tumors.