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Organic–inorganic hybrid nanocomposites (OIHN), with tailored surface chemistry, offer ultra-sensitive architecture capable of detecting ultra-low concentrations of target analytes with precision. In the present work, a novel nano-biosensor was fabricated, acquainting dynamic synergy of reduced graphene oxide (rGO) decorated hexagonal boron nitride nanosheets (hBNNS) for detection of carcinoembryonic antigen (CEA). Extensive spectroscopic and microscopic analyses confirmed the successful hydrothermal synthesis of cross-linked rGO-hBNNS nanocomposite. Uniform micro-electrodes of rGO-hBNNS onto pre-hydrolyzed ITO were obtained via electrophoretic deposition (EPD) technique at low DC potential (15 V). Optimization of antibody incubation time, pH of supporting electrolyte, and immunoelectrode preparation was thoroughly investigated to enhance nano-biosensing efficacy. rGO-modified hBNNS demonstrated 29% boost in electrochemical performance over bare hBNNS, signifying remarkable electro-catalytic activity of nano-biosensor. The presence of multifunctional groups on the interface facilitated stable crosslinking chemistry, increased immobilization density, and enabled site-specific anchoring of Anti-CEA, resulting in improved binding affinity. The nano-biosensor demonstrated a remarkably low limit of detection of 5.47 pg/mL (R2 = 0.99963), indicating exceptional sensitivity and accuracy in detecting CEA concentrations from 0 to 50 ng/mL. The clinical evaluation confirmed its exceptional shelf life, minimal cross-reactivity, and robust recovery rates in human serum samples, thereby unraveling the potential for early, highly sensitive, and reliable CEA detection. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) and M13 bacteriophage can self-assemble to form ultra-low density porous structures, known as GraPhage13 aerogels (GPA). Due to the insulating nature of GPA and the challenges in producing highly conductive aerogels, it is paramount to explore ways to enhance the conductivity of GPA. Herein, we have developed a method to enhance the conductivity of GPA, via the integration and optimisation of 5 nm and 20 nm diameter gold nanoparticles (AuNPs) into the aerogel structure and systematically analysed the morphology, composition and spectroscopic properties of the resulting GPA-Au nanocomposite. The fabricated GPA-Au nanocomposites exhibited remarkable increases in conductivity, with the integration of 5 nm AuNPs leading to a 53-fold increase compared to GPA, achieving a performance of up to 360 nS/cm, which is within the range suitable for miniaturised semiconductor devices. The mechanism behind the conductivity enhancement was further investigated and attributed to GO-AuNP interactions increasing the carrier density by introducing new energy levels in the GO band gap or shifting its Fermi level towards the conduction band. These findings demonstrate the potential of functionalised AuNPs to significantly improve the electrical properties of GPA, paving the way for their application in gas sensors for biological and chemical detection and a new range of advanced semiconductor devices. [ABSTRACT FROM AUTHOR]

Although graphene oxide (GO) has extensive recognized application prospects in slow-release fertilizer, plant pest control, and plant growth regulation, the incorporation of GO into nano herbicides is still in its early stages of development. This study selected a pair of sweet corn sister lines, nicosulfuron (NIF)-resistant HK301 and NIF-sensitive HK320, and sprayed them both with 80 mg kg–1 of GO-NIF, with clean water as a control, to study the effect of GO-NIF on sweet corn seedling growth, photosynthesis, chlorophyll fluorescence, and antioxidant system enzyme activity. Compared to spraying water and GO alone, spraying GO-NIF was able to effectively reduce the toxic effect of NIF on sweet corn seedlings. Compared with NIF treatment, 10 days after of spraying GO-NIF, the net photosynthetic rate (A), stomatal conductance (Gs), transpiration rate (E), photosystem II photochemical maximum quantum yield (Fv/Fm), photochemical quenching coefficient (qP), and photosynthetic electron transfer rate (ETR) of GO-NIF treatment were significantly increased by 328.31%, 132.44%, 574.39%, 73.53%, 152.41%, and 140.72%, respectively, compared to HK320. Compared to the imbalance of redox reactions continuously induced by NIF in HK320, GO-NIF effectively alleviated the observed oxidative pressure. Furthermore, compared to NIF treatment alone, GO-NIF treatment effectively increased the activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) in both lines, indicating GO induced resistance to the damage caused by NIF to sweet corn seedlings. This study will provides an empirical basis for understanding the detoxification promoting effect of GO in NIF and analyzing the mechanism of GO induced allogeneic detoxification in cells. [ABSTRACT FROM AUTHOR]

Nanofluid plays an important role in heat transfer engineering as a heat transfer medium. Therefore, we developed graphene oxide (GO)/carboxylated ferric tetroxide (Fe3O4–COOH) nanofluid with high stability using a two-step method. The preparation, characterization, physical properties and heat transfer properties of nanoparticles and nanofluids were investigated. The results show that GO/Fe3O4–COOH(GF) nanofluids present high stability at low concentrations (0.01 mass%, 0.05 mass% and 0.10 mass%) with absolute values of Zeta potential value greater than 30 mV. By adjusting the pH, it was found that GF nanofluids presented the best stability at pH = 10. A study of the physical properties of the nanofluids revealed that the viscosity of the GF nanofluids did not increase excessively with the addition of Fe3O4–COOH nanoparticles relative to the GO nanofluids. The heat transfer platform tests revealed that compared with the same concentration of GO nanofluids, the GF nanofluids have significantly higher heat dissipation efficiency. The temperature drop of 0.05 mass% GF nanofluid is higher than that of deionized water at the same pump power. We believe that well-stabilized GO nanofluids incorporating Fe3O4–COOH will provide more meaningful value in heat exchange than GO nanofluids. [ABSTRACT FROM AUTHOR]

To explore the effect of acid rain corrosion on the cohesion performance of asphalt and its mechanism, graphene oxide (GO) was used to modify epoxy asphalt and 70# base asphalt, TAFPACK Super (TPS) high viscosity asphalt and epoxy asphalt were used as the control group, the periodic dry–wet cycle immersion test was used to simulate the acid rain environment to study the effect of acid rain on the physical properties, composition, cohesion and adhesion between different asphalt binders and aggregates. Furthermore, combined with aging test, the aging resistance of each asphalt after acid corrosion was investigated. The results show that acid rain corrosion can significantly decrease the adhesion between asphalt and aggregates and the cohesion of asphalt itself, resulting in serious moisture damage of asphalt. GO modified epoxy asphalt has better acid rain corrosion resistance than other asphalt. GO improves the cross-linking density between asphalt molecules. The polar groups and low shrinkage thermosetting resin of GO modified epoxy asphalt make it has excellent adhesion and high cohesion, which can effectively resist moisture erosion, peeling and temperature stress cracking, thus effectively resist the corrosion of acid rain. Aging deteriorates the performance of asphalt binder and decreases its acid corrosion resistance. GO modified epoxy asphalt can effectively inhibit the aging of asphalt binder, thus resisting the deterioration caused by aging. [ABSTRACT FROM AUTHOR]

A composite based on Fe3O4 nanoparticles, graphene oxide, and a ionic liquid (1-butyl-3-methylimidazolium-2-carboxylate) is proposed as a sorbent for the extraction of bisphenol A (BPA) from bottom sediments by matrix solid-phase dispersion (MSPD). The saturation magnetization of the synthesized sorbent is 34 emu/g. Grinding of bottom sediments and subsequent grinding with a sorbent was carried out in a ball mill. Some stages of MSPD were partially automated, in particular, the procedures of magnetic separation, BPA desorption, and sorbent regeneration. The recovery of BPA under the experimentally selected conditions (sorbent mass 0.5 g, time required to grind the sorbent 5 min) was 94%. The sorbent can withstand four sorption-desorption cycles without a loss of sorption capacity. To purify the matrix from interferents, washing with n-heptane was proposed. Bisphenol A was determined by gas chromatography–mass spectrometry after derivatization with acetic anhydride. The analytical characteristics of the method were established using model samples of bottom sediments artificially contaminated with BPA. The limit of determination using the developed method is 0.1 μg/kg, the linearity range of the calibration curve is 0.3–12 μg/kg (r2 = 0.994). As real samples for analysis, we used bottom sediments selected near the discharge of wastewater treatment plants in the city of Voronezh (Voronezh River and Don River). The BPA concentration in bottom sediments is 3.83–6.52 μg/kg. [ABSTRACT FROM AUTHOR]

Designing scaffolds to fit with essential requirements for wound dressings is still a challenge. A material with high antibacterial activity and biocompatibility is targeted. In this case, the electrospinning technique is used to fabricate a nanofiber scaffold of polylactic acid (PLA) embedded with ginger and/or molybdenum trioxide (MoO3) and cupric oxide (CuO). The nanofiber scaffolds were examined using SEM, TEM, Raman, XRD, FTIR, and EDX. In addition, the surface topography of the nanofiber scaffold of MoO3/ginger@PLA showed that the nanofiber diameters differ from 0.085 to 0.34 µm. Furthermore, the contact angle of the water drop on the surface of the pure PLA and MoO3/CuO/GO/ginger@PLA is remarkably changed from 32.3° to 18.9°. Moreover, the cell viability test of the composition MoO3/CuO/GO/ginger@PLA is above the IC50 at all concentrations. Meanwhile, the antibacterial test exhibited antibacterial activity against E. coli and S. aureus for the scaffolds, with an inhibition zone of 23 ± 0.816 mm and 16.33 ± 0.942 mm for MoO3/CuO/ginger@PLA and 20.3 ± 0.471 mm and 15.33 ± 0.943 mm for MoO3/CuO/GO/ginger@PLA. The obtained results are appropriate to aid the cells to grow and proliferate. As a result of that, the fabricated scaffolds could be utilized in biomedical applications. [ABSTRACT FROM AUTHOR]

Antibacterial dressings play an important role in wound management, especially in chronic wounds. Due to the excellent water retention, antibacterial hydrogel has become an ideal wound dressing. In this paper, the effective antibacterial dressing was constructed with the poly N-isopropylacrylamide (PNIPAM) hydrogel and graphene oxide loading nanosilver particles (GO-Ag) by the in situ chemical crosslinking method. The molecular structure, viscosity and mechanical properties, antibacterial agent content, antibacterial performance, temperature-sensitive antibacterial relationship and biocompatibility of PNIPAM-based GO-Ag composite hydrogel (PNIPAM/GO-Ag) were systematically characterized by the scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), plate counting and other methods. The results showed that the introduction of GO-Ag increased the pore structure of PNIPAM/GO-Ag hydrogel and provided more active sites for the release of silver nanoparticles, wherein the content of nanosilver in PNIPAM/GO-Ag hydrogel was only 0.01%, meeting the requirements of application as antibacterial dressings. Moreover, when the hydrogel was subjected to heat contraction, silver nanoparticles could release more quickly and efficiently. The antibacterial rates of the PNIPAM/GO-Ag hydrogel against E. coli and S. aureus were 99.8 and 99% at 37 °C, respectively, higher than those at 25 °C (92, 95%). Compared with the pure PNIPAM hydrogel (1423.0%), the swelling rate of PNIPAM/GO-Ag hydrogel could reach 2024.6%, certifying its ability to absorb exudate of wound site. When the deformation was less than 80%, the hydrogel could maintain excellent elastic deformation recovery ability, and the viscosity of hydrogel at human body temperature was 38 Pa·s. These prove that it had a good fit with the skin, could dissipate more energy and restore shape. The hemolysis rate of PNIPAM/GO-Ag hydrogel was less than 5%, showing good bio-safety. These all demonstrated the PNIPAM/GO-Ag hydrogel can be used as a potential application for the skin wound dressing. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is a potential material for application as nano-reinforcements in cementitious composites owing to its high-water dispersibility, aspect ratio and outstanding mechanical characteristics. In this study, the combined effect of GO and fly ash on strength properties, stress–strain behaviour and static modulus of elasticity of high-strength concrete was investigated. In addition, microstructure has been characterized using SEM and EDS techniques. The addition of GO at 0.15% and the replacement of cement with fly ash at 10, 20 and 30% by weight was considered. The results exhibited that the addition of GO at 0.15% improved the compressive and flexural strength of concrete by 24.3 and 25.2%, respectively, at 7 days. The combined effect of GO and fly ash on the strength properties of concrete at 7 days was greater than control concrete demonstrating that GO can offset the effect of fly ash on delaying the strength growth at an early age. From the experimental results, it can be concluded that the addition of GO and fly ash into the concrete improved both the strength and elastic modulus, consequently exhibiting positive synergy in hybridizing GO and fly ash into the concrete. Also, the microstructure properties indicated that the GO and fly ash-based concrete mixes exhibited a denser microstructure. Furthermore, a nonlinear numerical model was also created for GO and fly ash-based concrete with finite element-based software ATENA-GiD to validate the experimental findings. The nonlinear numerical model successfully predicted the behaviour under monotonic axial compression and was quite beneficial in minimizing the tedious experimental testing. Finally, it is found that the findings of both the experimental and numerical investigations are in good agreement. [ABSTRACT FROM AUTHOR]

Graphene has intriguing electrical, mechanical, thermal and biological properties that are being investigated for use in composites, modern electronics, membranes, and in the industry. Also, graphene has huge biological applications. Hydroxypropyl methylcellulose (HPMC) is a widely used bio-polymer effective for various biomedical applications. As a filler in this polymer matrix, graphene oxide (GO), reduced graphene oxide (RGO) and silver (Ag) nanoparticles (NPs) can be used to improve various properties of the matrix. They are also beneficial for bio-applications like drug delivery, the production of reactive oxygen species (ROS) and the antimicrobial properties of nanocomposite films. Here we synthesize a series of polymer nanocomposites taking GO, RGO and Ag NPs as a filler by the solution mixing method and explore the comparative biological application of such composites. We choose Ag NPs as it has the superior potential for multiple drug resistance. X-ray diffraction, Fourier-transform infrared and scanning electron microscope studies are used to describe how nanocomposites are formed. Energy-dispersive X-ray and dynamic mechanical analyzer analyses were also done to check elemental percentage in nanocomposite films and mechanical properties, respectively. To check several fruitful applications, antimicrobial properties, ROS generation and in-vitro drug release study of nanocomposite films with the loading of Ketorolac Tromethamine were also performed. [ABSTRACT FROM AUTHOR]

This study provides and investigates the fabrication of graphene oxide (GO) sheets decorated with chitosan nanoparticles (CSNP) through the hybridizing of GO and CS, by the addition of tetraethyl orthosilicate (TEOS) as a cross-linker agent. The fabricated GO-CSNP composite was characterized using several advanced techniques. Furthermore, various parameters affect the sorption of Sr(II), such as contact time, pH, initial concentration, dosage, temperature, and coexisting ions. The experimental results were in accordance with the pseudo-second-order reaction. The interaction mechanism between Sr(II) and GO-CSNP composite was accurately described by the Langmuir isotherm model with a maximum adsorption capacity of 473.93 mg/g. The GO-CSNP composite demonstrated exceptional selectivity for the sorption of Sr(II) over Y(III) at a high concentration ratio of 10:1 for Sr2+ to Y3+, respectively. Furthermore, the GO-CSNP adsorbent demonstrated considerable potential as a highly effective sorbent for the adsorption of Sr(II), Mo(VI), Cd(II), and Cs(I) ions. The results revealed that the prepared composite was effectively capable of removing various fission products. [ABSTRACT FROM AUTHOR]

A novel graphene-modified molecularly imprinted polymer-based electrochemical sensor (MIP/RGO-GCE) was developed for the sensitive and selective detection of sibutramine in sports doping control. The sensor was fabricated by electropolymerizing o-phenylenediamine on a reduced graphene oxide-modified glassy carbon electrode in the presence of sibutramine as the template molecule. Under optimized conditions, the MIP/RGO-GCE sensor exhibited a wide linear range (0.05 to 20 μM), low detection limit (0.02 μM), high sensitivity (1.27 μA/μM), good precision (RSD < 2.7%), and long-term stability (93.5% retention after two weeks). The sensor's applicability was successfully demonstrated by analyzing spiked human urine and serum samples, with recoveries ranging from 95.8 to 103.2% and good agreement with the reference HPLC method. Furthermore, the sensor showed a rapid response time of 5 s and excellent reproducibility with an RSD of 1.5% for repeated measurements. The proposed sensor offers a rapid, cost-effective, and reliable alternative to traditional chromatographic methods for sibutramine detection in sports doping control. [ABSTRACT FROM AUTHOR]

This work reports on the synthesis of a unique nickel oxide/carboxylated reduced graphene oxide (NiO/c-rGO) nanocomposites electrochemical sensor for the detection of quercetin (QCT). The successful integration of NiO nanoparticles into the c-rGO matrix was confirmed by the characterization and synthesis of both the NiO nanoparticles and c-rGO. After that, the glassy carbon electrode (GCE) was treated with the NiO/c-rGO nanocomposite, which produced a modified GCE with improved electrochemical characteristics. The NiO/c-rGO modified GCE showed a wide linear-range of 0.5 to 750 µM and a low detection limit of 0.016 µM, indicating high sensitivity towards QCT. Additionally, the sensor exhibited excellent selectivity, with very little interference from examined kinds of analytes, both organic and inorganic. Additionally, the sensor's long-term stability was demonstrated by its steady redox reaction to QCT, with a sensitivity of roughly 96.68% over a 33-day period. The suggested sensor's use was evaluated by measuring differential pulse voltammetry on real samples, including onions, apple juice, honey, and green tea. These samples' QCT recovery rates, which varied from 96.00 to 99.40%, showed the precision, dependability, and potency of the suggested sensor. Based on these results, the NiO/c-rGO nanocomposite may be a great material to use in the creation of stable, highly sensitive, and selective electrochemical sensors for QCT detection. The food, pharmaceutical, and clinical diagnostics industries might all benefit greatly from this. This work enhances the field of electrochemical sensor technology and paves the way for the development of further sensors using similar nanocomposites. [ABSTRACT FROM AUTHOR]

Cryoinjury mitigation is key in cell cryopreservation. Here, we aimed to assess the effectiveness of nanographene oxide (nano-GO) for improving cryoprotectant agents (CPAs) in human adipose stem cell (hADSC) cryopreservation. For in vitro experiments, nano-GO (5 μg/mL) was added to the CPAs in the control, and passage (P) 2 hADSCs were collected and cryopreserved for around two weeks. We compared cytotoxicity, cell viability, immunophenotypes, proliferation, cell apoptosis, and tri-lineage differentiation. In vivo, studies used lipoaspirate to create non-enriched or hADSC-enriched fat tissues by combining it with PBS or hADSCs cryopreserved with the aforementioned CPAs. Each nude mouse received a 0.3 mL subcutaneous injection of the graft. At 12 weeks, the grafts were harvested. Histology, adipocyte-associated genes and protein, vascular density and angiogenic cytokines, macrophage infiltration, and inflammatory cytokines were analyzed. Nano-GO CPA contributed to increased cell viability, improved cell recovery, and lowered levels of early apoptosis. Nano GO at concentrations of 0.01–100 μg/mL caused no cytotoxicity to hADSCs. The absence of nano GOs in the intracellular compartments of the cells was confirmed by transmission electron microscopy. The fat grafts from the CPA-GO group showed more viable adipocytes and significantly increased angiogenesis compared to the PBS and CPA-C groups. Adding hADSCs from the CPA-GO group to the graft reduced macrophage infiltration and MCP-1 expression. Nano-GO plays an anti-apoptotic role in the cryopreservation of hADSCs, which could improve the survival of transplanted fat tissues, possibly via improved angiogenesis and lower inflammatory response in the transplanted adipose tissue. [ABSTRACT FROM AUTHOR]

Nano-biocomposite hydrogel samples were produced using graphene oxide (GO) and agar and applied as adsorbents of organic components in water. The hydrogels were prepared by varying the wt% of Agar and GO. The samples were characterized, and batch adsorption experiments evaluated the effect of initial pH, equilibrium isotherms, and kinetics for the adsorption of the anionic dye Acid Orange 7 (AO) and the cationic dyes Nile Blue A (NB) and methylene blue (MB) in an aqueous medium. Overall, both hydrogel samples exhibited satisfactory results for removing NB and MB; however, there was no effective removal for the anionic dye AO. Adsorption equilibrium isotherms were obtained, and Freundlich, Langmuir, and Sips models were fitted to the experimental equilibrium data; moreover, kinetic data were adjusted to driving force models and particle mass balance. The maximum experimental adsorption capacities, 141.48 mg·g−1 (MB) and 284.69 mg·g−1 (NB), were obtained, on a dry basis, for the sample produced with 70 wt% of agar and 30 wt% of GO. Both hydrogels exhibited remarkable regenerative potential for NB and MB, with the adsorption capacity remaining constant, even after five adsorption/desorption cycles. [ABSTRACT FROM AUTHOR]

Aerogel-based composites hold promising application prospects as potential electromagnetic wave (EMW) absorption materials, yet the construction of such materials with ingenious microstructures, appropriate magnetic/dielectric multi-components, and integrated multifunctionality remains considerably challenging. Herein, a multicomponent Co/MnO/Ti3C2Tx MXene/rGO (CMMG) hybrid aerogel featured with three-dimensional (3D) vertical directional channel architecture is reported. Benefiting from the synergistic effect arising from the 3D conductive networking structure, diverse heterogeneous interfaces, magnetic/dielectric multicomponent, and multiple loss pathways, the optimized CMMG-2 aerogel delivers fascinating EMW absorption capabilities, characterized by a minimal reflection loss (RLmin) of −77.41 dB and an effective absorption bandwidth (EAB) of 6.56 GHz. Additionally, the remarkable hydrophobicity, exceptional thermal insulation capabilities, and outstanding photothermal properties of CMMG-2 aerogel make it highly promising for multiple application in diverse and demanding environments. Interestingly, the distinctive pore structure of hybrid aerogel also allows it for sensitive and reliable detection of electrical signals caused by pressure changes and human motion. Thus, this research provides a viable design strategy for the development of lightweight, efficient, and multifunctional aerogel-based EMW absorption materials for various application scenarios. [ABSTRACT FROM AUTHOR]

This study was conducted to generate and investigate the structural characteristics and antioxidant properties of a nano-composite film produced from Vicia ervilia protein (VEPI)—Launaea acanthodes gum (LAG). The film containing Silybum marianum extract microcapsules (SMEM) at varying volumes (0, 2.2, 7.5, 12.8, 15 v/v) along with different concentrations of graphene oxide nanoparticles (GONPs) (0, 0.6, 2.0, 3.4, 4.0 w/v). The thickness, solubility, and moisture content of the film samples increased after the integration of SMEM and GONPs (P < 0.05). Fourier-transform infrared analysis of the film sample based on VEPI/LAG/SMEM/GONPs showed proper interactions, including electrostatic interaction between these materials. X-ray diffraction analysis revealed a lower degree of crystallinity in the nano-composite film by adding GONPs and SMEM. The Differential scanning calorimetry analysis conducted on the composite and optimized films, integrating SMEM and GONPs, revealed an elevation in both the glass transition temperature and the thermal degradation temperature compared to the blank sample. The results obtained from Field emission scanning electron microscopy demonstrated that the type and quantity of variables significantly influenced the surface morphology of the films, leading to the formation of cracks and pores in the film. Furthermore, the findings regarding antimicrobial activity demonstrated that the nanocomposite film, incorporating SMEM and GONPs, exhibited antimicrobial properties against E. coli and S. aureus bacteria. According to our result VEPI/LAG/SMEM/GONPs nanocomposite film possess potential to be used as environment friendly packaging films to improve shelf life of food. [ABSTRACT FROM AUTHOR]

This article details the development of an electrically-responsive bending actuator from a graphene oxide (GO), nanosized-ZnO, and sulfonated poly(vinyl alcohol) (S-PVA) nanocomposite membrane coated with platinum (Pt). The solution-cast S-PVA/ZnO/GO/Pt membrane exhibits an ion-exchange capacity of 1.68 meq g−1 and favorable electrochemical characteristics. With a 67.28% water uptake after a 4 h immersion at 45 °C, it serves as the foundation for an ionic polymeric-metal composite (IPMC) actuator. Electrolessly plated Pt layers ensure slow water loss (31.6% after 12 min at 6 V), enhancing long-term durability. Electromechanical characterization reveals a 10 mm tip displacement at 3 V, indicating improved investigations. The resulting IPMC nanocomposite with Pt coating demonstrates excellent mechanical, electrical, and electrochemical capabilities for diverse applications. Comprehensive analyses, including SEM, EDX mapping, TGA, and XRD, elucidate the membrane's characteristics. This refined nanocomposite holds promising potential across various applications, offering enhanced invetigations and durability in electrically-driven actuation systems. [ABSTRACT FROM AUTHOR]

In the present study, a quaternary composite consisting of α-ketoglutaric acid, chitosan, polyaniline, and graphene oxide (α-CTS-PANI-GO) was synthesized and characterized by Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy, and Raman spectroscopy. The adsorption of dye on the film was proved by the X-ray diffraction analysis method. According to the increase in the intensity of the peak before and after adsorption, it showed the presence of Methylene Blue (MB) and Acid Orange 7 (AO7). Also, the appearance of peaks related to sulfur in Energy dispersive X-ray (EDX) and EDX elemental mapping, and X-ray photoelectron spectroscopy data after the adsorption process proved the presence of dyes compounds and their adsorption by the synthetic film. The simultaneous removal properties of α-CTS-PANI-GO were evaluated in the removal of cationic and anionic dyes, MB and AO7. Using the Central Composite Decomposition, the effect of different variables such as pH, temperature, adsorbent dose, and time on AO7 and MB removal was studied. The regeneration of α-CTS-PANI-GO film was studied and the zero point charge of the synthesized film was also determined. Various isotherm models, such as Langmuir and Freundlich, were investigated, and the processing of experimental equilibrium data confirmed the suitability and application of the Langmuir model. Analysis of experimental adsorption data using various kinetic models, such as pseudo-first and second-order models, shows the applicability of the first-order equation. The results showed that in the optimal conditions, the removal percentage was about 95% for AO7 and 80% for MB, which indicates the successful performance of the synthetic film compared to the method. [ABSTRACT FROM AUTHOR]

Polyhydroxyurethane (PHU) with free secondary amine groups was synthesized by reacting poly(ethylene glycol)bis-cyclic carbonate with triethylenetetramine. PHU was mixed with varying amounts of gelatin (GE) and crosslinked by reacting them with either poly(ethylene glycol)glycidyl ether (PEGDE) or 1,4-butanediol diglycidyl ether (BDDE). The tensile strength and fluid handling capacity of the monolayer films obtained from different formulations of PHU, GE, PEGDE, or BDDE were evaluated. To further improve the tensile strength of dressings via increasing the crosslinking of the networks, varying amounts of epoxidized graphene oxide (EGO) were utilized as an auxiliary crosslinking agent. The improved tensile strength of up to 140% was recorded for these samples. Additionally, the membranes containing EGO were able to absorb near-infrared light. The resulting hyperthermia effect (increasing temperature up to about 63 within 15 min) could efficiently kill bacteria (100% killing). The free secondary amine groups on the PHU backbone also reduced the silver ions loaded into the dressings, and resulting silver nanoparticles (Ag NPs) showed acceptable antibacterial activity against E.coli (53% killing) and S.aureus (78% killing). It was also found that the antibacterial activity of AgNPs-containing samples was further improved after incorporating EGO due to the knife-killing effect of EGO nanoplates. [ABSTRACT FROM AUTHOR]

High-performance energy storage devices, such as portable electronic devices and electrically powered cars, need high electrochemical performances (energy and power densities). Supercapacitors are high-performance energy storage devices that have high specific capacitances and power densities. A new electrode design is compulsory to reach the target. So, its surface morphology, surface area, pore structures and charge carrier properties can be controlled to obtain a high-performance energy storage devices. In this study, bicyclo (2.2.1)-hept-5-en-2-carboxylic acid was chemically synthesized for use as a dopant in electrode materials. Furthermore, graphene oxide (GO) was synthesized by the modified Hummers method. The functional end groups of GO were activated by the acid dopant. Activated carbon (AC) was used as an electrode component for the biomass material of walnut sheels. AC/GO/acid was formed as a slurry using N-methyl-2-pyrrolidone. This mixture was electropolymerized with a thiophene (Th) monomer on an Au electrode with a 3-electrode system by the CV method. After removing the AC/GO/acid/PTh active materials on the Au electrode (called as C-1; C-2; C-3 with changing of acid content in the nanocomposite), the electrode was fabricated as a symmetrical 2 electrode supercapacitor device. Each component of the active materials was characterized by solid-state conductivity, SEM–EDX, FTIR-ATR, TGA-DTA, and BET analyses. Moreover, the electrochemical performance of supercapacitors, including CR2032 coin cells, was tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods. The highest specific capacitance was obtained at Csp = 743.70 F/g at 2 mV/s for AC/GO/PTh nanocomposite (C-4), which does not contain a dopant agent (acid). The highest conductivity was observed as σ = 2.61 × 10−5 S/cm in the highest acid content (18%) in the nanocomposite for C-3. The conductivity of C-3 is ~ 13.0 times greater than that of C-4. In addition, long-term stability tests (1000 and 5000 cycles) and equivalent circuit model analysis (Randless circuit, (Rs(CRct))) were carried out with 4 different composite materials for supercapacitor devices. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is an important half-reaction in various energy devices such as fuel cells. Here, 2D dendritic Fe/N co-doped carbon-based nanosheet composites (L-Fe-CNT@NCS-900) were obtained by high-temperature calcination using ZIF-L generated in the aqueous phase as a precursor and Vitamin C as a modifier. It is found that the catalysts calcined at 900℃ possessed the large specific surface area and the pore size distribution graphs showed a narrow micropore size distribution centered at about 1.8 nm. Furthermore, the Fe-N-C species was detected, which further improved the ORR performance as an active center. Thus, the L-Fe-CNT@NCS-900 calcined at 900 °C achieved the best ORR performance with a half-wave potential (E1/2) of 0.85 V, and the hydrogen peroxide yield is only about 4% during the ORR process. Meanwhile, L-Fe-CNT@NCS-900 exhibited outstanding methanol resistance. This work proposes a new strategy for constructing an efficient electrocatalysts for oxygen reduction reaction. [ABSTRACT FROM AUTHOR]

The solution casting method was used to synthesize nanocomposites of polymethyl methacrylate (PMMA) and polystyrene (PS) polymer with graphene oxide (GO). It was determined that the conductivity of the PS/GO and PMMA/GO polymer nanocomposites was ionic and electronic, respectively. The thermal conductivity of the nanocomposites was investigated with regard to the impact of crystallinity and free volume. This paper reports a differential scanning calorimetric (DSC) study of PMMA/GO (1%) and PS/GO (1%) and nanocomposite blends of PMMA and PS prepared in different ratios by weight percentage of PMMA/PS (80:20, 60:40, 50:50, 60:40, 20:80) with 1% of GO using the solution casting method. The samples were analyzed using a DSC instrument at heating rates of 5°C/min, 10°C/min, and 20°C/min in the temperature range of 50–160°C. Fourier transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD) studies of the blends showed that the crystalline phases of PS and PMMA depended on the GO percentage in the composite solutions. Significant shifts were seen in FTIR, XRD, and DSC analyses, and DSC and TGA thermograms of the nanocomposite blend confirmed the formation of a PS/PMMA blend and demonstrated a significant change in thermal behavior with the blend ratio. The activation of the pure and blended polymers was determined through their glass transition using different isoconversional methods. [ABSTRACT FROM AUTHOR]

Increasing global water shortages are accelerating the pace of membrane manufacturing, which generates many environmentally harmful solvents. Such challenges need a radical rethink of developing innovative membranes that can address freshwater production without generating environmentally harmful solvents. This work utilized the synthesized ultra-long hydroxyapatite (UHA) by the solvothermal method using the green solvent oleic acid in preparing UHA-based forward osmosis membranes. The membranes were developed using different loading ratios of graphene oxide (GO) by vacuum-assisted filtration technique. The prepared GO/UHA membranes were identified using X-ray diffraction, scanning electron microscope, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Water contact angle and pore size distribution were determined for the obtained GO/UHA membranes. The obtained hierarchical porous structure in the prepared membranes with interconnected channels results in a stable water flux with reverse salt flux. The best water flux rate of 42 ± 2 L·m−2·h−1 was achieved using the 50 mg GO/UHA membrane, which is 3.3 times higher than the pristine membrane, and a reverse salt flux of 67 g·m−2·h−1. The obtained results showed a promising capability of a new generation of sustainable inorganic-based membranes that can be utilized in freshwater generation by energy-efficient techniques such as forward osmosis. [ABSTRACT FROM AUTHOR]

2D graphene oxide (GO) membranes are gaining prominence for water reclamation from oily wastewater. Unresolved challenges include low membrane permeance from tight sheets and fouling during separation. In this work, a bioinspired Arabic gum (AG) was used as an intercalated agent with the help of glutaraldehyde to improve the GO membranes' permeation and fouling resistance. The 2D-laminated separating layer is crafted through a self-assembling innovative approach utilizing pressurized dead-end assembly. The Arabic gum intercalated graphene oxide-modified ceramic membrane (AGIGO-CM) appeared superhydrophilic and underwater (UW) superoleophobic with a UW oil contact angle (UWOCA) of 156.1 ± 1.2°. The membrane prepared with 1 mg of AGIGO (AGIGO-1-CM) offers a flux of 17 times higher than pristine graphene oxide (p-GO) while maintaining a separation efficiency of >99% during the separation of the oil-in-water emulsions. Molecular dynamics (MD) simulations showed AG intercalation expanding the interlayer distance by up to 20 Å, with AGIGO having a higher fractional free volume (FFV) of 0.986 compared to p-GO's 0.599. AGIGO-CM displayed lower interfacial formation energy (EIFE) of −1865.2 kcal/mol versus −765.5 kcal/mol for p-GO, indicating easier separation. It is further supported by the substantial interfacial thickness of 148 Å for AGIGO-CM compared to 53.0 Å for the p-GO membranes. AGIGO-CM showed minimal fouling, retaining >99% separation efficiency for 6 h. Compared to p-GO-CM, AGIGO-CM flux decreased by only 17.84% versus 44.72%. AGIGO-CM exhibited stability even in acidic and basic environments, showcasing its potential for high performance. [ABSTRACT FROM AUTHOR]

Adsorption has been reported to be optimal among oil spill cleanup methods due to its simplicity, low capital and operational cost, high removal efficiency and environmental friendliness. However, its continuous usage has been linked to generation of enormous waste, after oil spill cleanup, to which use of reusable oil sorbents has been proposed as a possible solution. Synthetic organic oil sorbents have high mechanical properties compared to other categories of oil sorbents, but they suffer low adsorptive capacities. To address this problem, among other nanoparticles, rGO have been infused in polymeric materials to produce composite oil sorbents characterized with high adsorptive capacities. In this research, surface modified rGO was infused in waste expanded polystyrene, to produce electrospun PS/FrGO composite sorbents by solution blending and electrospinning method. Adsorptive capacities of produced composites were evaluated in four oil samples. Functionalization of rGO was found to cause removal of residual oxygen containing functional groups such as hydroxyl (–OH), and resulted in more hydrophobic surface. Infusion of FrGO, in waste expanded polystyrene resulted into composites with increased surface area, from 71.50 m2/g for pure PS20 to 353.45 m2/g, 429.18 m2/g, 456.14 m2/g for PS20 infused with 1, 2 and 4wt% of FrGO. Increase in oil sorption capacities of the composite, observed in four oil samples corresponds to improved surface area. Produced composites show good recyclability in the four oil samples, at least up to the third sorption cycle. Highlights: Modification of Graphene oxide (GO) to reduced Graphene Oxide (rGO) rGO was functionalized and infused in Polystyrene (PS) to form PS/FrGO composite PS/FrGO composite was applied to oil–water mixture for oil adsorption Reusability of composites produced was evaluated. [ABSTRACT FROM AUTHOR]

Due to the rising human population and industrialization, harmful chemical compounds such as 4-nitrophenol (4-NP) and various dyes are increasingly released into the environment, resulting in water pollution. It is essential to convert these harmful chemicals into harmless compounds to mitigate this pollution. This research focuses on synthesizing a novel heterogeneous catalyst using modified canvas fabric (CF) decorated with silver metal nanoparticles on graphene oxide nanosheets (Ag-GO/CF). The process involves coating the fabrics (CF) with graphene oxide (GO) nanosheets through sonication. Subsequently, silver nanoparticles are deposited in situ and reduced on the GO surface, resulting in the formation of the Ag-GO/CF composite. Various physicochemical characterizations were conducted to examine the interfacial interactions between CF, GO, and Ag nanoparticles. The catalytic activity of the nanocomposite was assessed by hydrogenating 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of sodium borohydride (NaBH4). The results showed that the 10%Ag-5%GO/CF with a surface of 6 cm2 (3 × 2 cm) exhibited the highest catalytic activity, achieving a reduction efficiency of over 96% in 5 min. The 4-NP reduction reaction rate was well-fitted with a pseudo-first-order kinetics model with an apparent reaction rate constant (Kapp) of 0.676 min−1. Furthermore, the Ag-GO/CF composite demonstrated remarkable stability over successive cycles, with no noticeable decrease in its catalytic activity, suggesting its promising application for long-term chemical catalytic processes. This synthesized composite can be easily added to and removed from the reaction solution while maintaining high catalytic performance in the reduction of 4-NP, and it could be beneficial in avoiding problems related to powder separation. [ABSTRACT FROM AUTHOR]

This research developed a novel composite of MOF-NH2 and graphene oxide (GO) for enhanced CO2 capture. Employing the response surface methodology-central composite design (RSM-CCD) for experiments design, various MOF-NH2/GO samples with GO loadings from 0 to 30 wt% were synthesized. The results of SEM, XRD, EDS, and BET analysis revealed that the materials maintained their MOF crystal structure, confirmed by X-ray diffraction, and exhibited unique texture, high porosity, and oxygen-enriched surface chemistry. The influence of temperature (25–65 °C) and pressure (1–9 bar) on CO2 adsorption capacity was assessed using a volumetric adsorption system. Optimum conditions were obtained at weight percent of 22.6 wt% GO, temperature of 25 °C, and pressure of 9 bar with maximum adsorption capacity of 303.61 mg/g. The incorporation of amino groups enhanced the CO2 adsorption capacity. Isotherm and kinetic analyses indicated that Freundlich and Fractional-order models best described CO2 adsorption behavior. Thermodynamic analysis showed the process was exothermic, spontaneous, and physical, with enthalpy changes of − 16.905 kJ/mol, entropy changes of − 0.030 kJ/mol K, and Gibs changes energy of − 7.904 kJ/mol. Mass transfer diffusion coefficients increased with higher GO loadings. Regenerability tests demonstrated high performance and resilience, with only a 5.79% decrease in efficiency after fifteen cycles. These findings suggest significant potential for these composites in CO2 capture technologies. [ABSTRACT FROM AUTHOR]

The global concern over water pollution caused by contaminants of emerging concern has been the subject of several studies due to the complexity of treatment. Here, the synthesis of a graphene oxide-based magnetic material (GO@Fe3O4) produced according to a modified Hummers' method followed by a hydrothermal reaction was proposed; then, its application as a photocatalyst in clonazepam photo-Fenton degradation was investigated. Several characterization analyses were performed to analyze the structure, functionalization and magnetic properties of the composite. A 23 factorial design was used for the optimization procedure to investigate the effect of [H2O2], GO@Fe3O4 dose and pH on clonazepam degradation. Adsorption experiments demonstrated that GO@Fe3O4 could not adsorb clonazepam. Photo-Fenton kinetics showed that total degradation of clonazepam was achieved within 5 min, and the experimental data were better fitted to the PFO model. A comparative study of clonazepam degradation by different processes highlighted that the heterogeneous photo-Fenton process was more efficient than homogeneous processes. The radical scavenging test showed that O 2 · - was the main active free radical in the degradation reaction, followed by hydroxyl radicals (•OH) and holes (h+) in the valence layer; accordingly, a mechanism of degradation was proposed to describe the process. [ABSTRACT FROM AUTHOR]

A novel chelating adsorbent based on (3-iminodiacetic acid) propyltriethoxysilane graphene oxide (IAT-GO) has been developed, showing exceptional promise for capturing lead. IAT-GO is made by combining a high-surface-area graphene oxide with a specially designed chelating ligand, which can selectively and efficiently remove lead. The synthesis of IAT-GO involves a two-step progression. In the first step, covalent bonds form between graphene oxide and (3-aminopropyl)-triethoxysilane (AT) through hydrolysis, condensation, and epoxide ring opening reactions. In the second step, nucleophilic substitution reactions occur between the primary amines and chloroacetic acid (CAA). A comprehensive suite of characterization techniques, including XPS, UV–Vis, XRD, Raman, FTIR, TEM, and SEM, provides detailed insights into the IAT-GO adsorbent's chemical composition and physical form, elucidating its intricate structure and morphology. Optimizing the experimental conditions for using the adsorbent material to remove Pb(II) ions from contaminated water revealed a maximum adsorption capacity of 124.0 mg/g at pH 5 and 30 min. The IAT-GO displays high selectivity for Pb(II) in a mixture of six metal ions containing 100 ppm of each one. Moreover, the IAT-GO shows 100% removal of Pb(II) for concentrations lower than 50 ppm. The excellent fit of the experimental data with the Langmuir adsorption isotherm and pseudo-second-order kinetic models (R2 > 99%) indicates that Pb(II) ion uptake onto the IAT-GO surface occurs via the monolayer formation of mercury ions. IAT-GO demonstrates exceptional potential as an innovative adsorbent for lead-contaminated water. Nitric acid (0.4 M) effectively regenerates the material, while its reusability remains impressive even after five cycles (> 97% removal efficiency). Therefore, this study highlights the development of a groundbreaking material, IAT-GO, with exceptional potential for remediating lead-contaminated water. Its high efficiency, selectivity, reusability, and cost-effectiveness make it a promising candidate for real-world applications. [ABSTRACT FROM AUTHOR]

A porous electrode material consisting of NiCo2O4/RGO with an approximate diameter of 200 nm has been successfully fabricated. This promising porous material was derived from ZIF-67/RGO (zeolitic imidazolate framework-67 crystals doped with reduced graphene oxide sheets) through an ion exchange and etching process using Ni(NO3)2·6H2O followed by a thermal reaction. The composition was analyzed using spectroscopic and morphological techniques. The obtained porous and hollow structure of NiCo2O4/RGO contains rich active sites. Additionally, its improved performance and stability were demonstrated using potassium ferricyanide (K3[Fe(CN)]6) (PFC) and sodium hydroxide (NaOH) as an electrolyte. NiCo2O4/RGO in NaOH/PFC exhibited a maximum estimated specific capacitance of 212.5 F g−1 at 0.5 A g−1 and demonstrated excellent retention value reaching 91.7% after applying 10,000 cycles at 20 A g−1. This symmetric supercapacitor achieved an outstanding energy density (Ed) of 75.54 Wh kg−1 at a power density (Pd) of 1.6 kW kg−1 at 0.5 A g−1. Surprisingly, there is a 2.5-fold enhancement in Ed (from 32.44 to 75.54 Wh kg−1) of NiCo2O4/RGO through the addition of 0.3 M PFC into 3 M NaOH. The results indicate that the NiCo2O4/RGO electrode could be ideal for supercapacitors. [ABSTRACT FROM AUTHOR]

The review study was carried out to investigate the effect of metal oxide (MO) nanoparticles on the characteristics of a polymeric matrix. Polyaniline, more commonly known as PANI, is one of the most addressed intrinsically conducting polymers. PANI was chosen as a promising conducting polymer among the competition and its application range was expanded by combining it with various components, including graphene, graphene oxide, metal oxide, carbon, carbon nanotubes, silicon, silicon dioxide, biomolecules, and metal–organic frameworks. This review illustrates how polyaniline can be doped with metal oxide nanoparticles notably Al2O3, CeO2, CuO, NiO, TiO2, and ZnO. Furthermore, the synthesis, characteristics, and applications of PANI metal oxide nanocomposites were also addressed. Since metal oxides (MO) already have a wide range of applications, combining PANI with MO can create a world of opportunity. An effort has been attempted in order to bring close enough to the recently focused study field of PANI-MO nanocomposites. [ABSTRACT FROM AUTHOR]

Carbon emission reduction has been accepted as a common concern all over the world. Currently, CO2 emission is mainly derived from the consumption of fossil fuels. To solve this issue, there is an urgent need to develop technologies for CO2 capture. The utilization of membrane technology to remove CO2 from a mixture gas attracts great interest. In the present work, poly(2-hydroxyethyl methacrylate-co-vinylamine) was synthesized by polymerization (n-vinyl formamide and 2-hydroxyethyl methacrylate), hydrolysis, and ion exchange. The surface function of graphene oxide was carried out by aerobic self-polymerization of dopamine. The mixed matrix membranes were fabricated by adding the nanofiller (before and after modification) into the polymeric matrix. The membrane properties and its structure were characterized by FTIR, TGA, XRD, and SEM. The effect of nanofiller content and operation conditions on membrane performance was investigated. Results showed that the additions of nanofiller could decrease the crystallization of these membranes and effectively improve gas permeance. Remarkably, for the addition of 2.0 wt% dopamine-modified graphene oxide, the CO2 permeance of the membrane was increased by 30.9% while achieving a CO2/N2 selectivity of 83.5. The CO2 permeation for CO2/CH4 was also increased by 16.77%. These were surpassed over the 2008 Robeson's upper bound. These resultant membranes demonstrated attractive potential for low-pressure post-combustion CO2 capture. Besides, the stability of longtime tests on membranes was studied, and it was observed that membranes exhibited excellent stabilization with continuously operated for 220 h. The excellent properties of these membranes provide new opportunities for gas separation applications. [ABSTRACT FROM AUTHOR]

This study presents the eco-friendly composites coating with advanced properties that are prepared by chitosan (CS)-modified graphene oxide (GO) filled acrylic-based coating. Photo-curable acrylic-based nanocomposite containing different amounts of chitosan-modified graphene oxide (CS–GO) and the effect of CS–GO on the coating morphology, UV-curing, transparency, tribological, antimicrobial, thermal and anticorrosion properties was studied. The curing study confirmed that the CS–GO absorbed photon but did not affect the final conversion of the coatings. The results of corrosion analysis demonstrated that the CS–GO filled nanocomposite coatings have higher corrosion protection ability than that of pure acrylic and GO filled coatings. The antimicrobial properties of CS–GO filled coating showed that the antimicrobial performance enhanced as the concentration of CS–GO increased. The optical transmittance study shows that the coating's film transparency decreased with increasing CS–GO concentration, but all of the nanocomposite coatings have a high visible transmittance. This study attributes the enhanced properties to the dispersion of the chitosan-modified GO, which greatly improved the interfacial strength of CS–GO and polymeric matrix and enhanced corrosion properties. [ABSTRACT FROM AUTHOR]

Pesticide residues determination has become an increasingly serious issue due to their detrimental effects on environmental and human health. Therefore, developing sensitive and rapid methods for monitoring pesticides in water and food samples is important. Herein, pipette-tip micro-solid-phase extraction (PT-µSPE) based on electrospun poly (vinyl alcohol) (PVA)/citric acid (CA)/Mg-MOF@ graphene oxide (GO) was developed for extraction of atrazine and malathion prior to corona discharge ion mobility spectrometer (CD-IMS). The sorbent type and its amount, sample volume, adsorption and desorption cycles, sample pH, solvent type and its volume were opted. According to the analytical investigation, the composite nanofibers demonstrated high surface area, porous structure, and remarkable extraction efficiency. Additionally, the incorporation of GO into MOFs improved both Mg-MOF and GO extraction properties, resulting in more analyte adsorption. Under opted conditions, the relative standard deviation values (RSDs %) below 6.9% with spiked-sample recoveries of 79.2–95.9% were achieved for both pesticides. Quantification was accomplished by matrix-matched calibration plots, which showed good linearity ranging between 8.0 and 1300.0 ng mL−1 for atrazine and 10.0–1500.0 ng mL−1 for malathion (R2 > 0.99), with limits of detection (LODs) of 2.5 and 3.5 ng mL−1, respectively. Eventuality, the capability of the procedure was examined successfully by monitoring the selected analytes in orange, apple, and tomato juices. The most founded pesticide residues were below the maximum residue limits (MRL = 8.0 mg L−1) for food samples. [ABSTRACT FROM AUTHOR]

The synergistic potential of using graphene oxide (GO) nanosheets and hydrolyzed polyacrylamide (HPAM) as GO enhanced polymer hybrid (GOeP) for enhancing oil recovery (EOR) purposes has drawn attention. However, the hybridization method and stability of GOeP have not been comprehensively studied. To cover this gap, the current study evaluates the stability of GOeP under different conditions, including temperatures such as 60 and 80 °C, high and low salinities, and the presence of Mg2+ ions (6430 and 643 ppm). Hence, GO nanosheets were synthesized and characterized through XRD, Raman, FTIR, and DLS techniques. The performance of five preparation methods was assessed to determine their ability to produce stable hybrids. Zeta potential and sedimentation methods, coupled with the ANOVA statistical technique, were used for measuring and interpreting stability for 21 days. Results revealed that the stability of GOeP in the presence of brine is influenced by hydrolyzation duration, the composition of the water used in polymer hydrolyzation, the form of additives (being powdery or in aqueous solution), and the dispersion quality, including whether the GO solution was prediluted. The results revealed that the positive impact of higher temperatures on the long-term stability of GOeP is approximately seven times less significant than the reduction in stability caused by salinity. Under elevated salinity conditions, a higher Mg2+ concentration led to an 80% decrease in long-term stability, whereas the temperature impact was negligible. These findings highlight the potential of GOeP for EOR applications, offering insights into optimizing stability under challenging reservoir conditions. [ABSTRACT FROM AUTHOR]

Exposure to altered gravity influences cellular behaviour in cell cultures. Hydrogels are amongst the most common materials used to produce tissue-engineering scaffolds, and their mechanical properties play a crucial role in cell-matrix interaction. However, little is known about the influence of altered gravity on hydrogel properties. Here we study the mechanical properties of Poly (ethylene glycol) diacrylate (PEGDA) and PEGDA incorporated with graphene oxide (GO) by performing tensile tests in micro and hypergravity during a Parabolic flight campaign, and by comparing them to the same tests performed in Earth gravity. We show that gravity levels do not result in a statistically significant difference in Young's modulus. [ABSTRACT FROM AUTHOR]

High ammonia concentrations in anaerobic degradation systems cause volatile fatty acid accumulation and reduced methane yield, which often derive from restricted activity of syntrophic acid-oxidising bacteria and hydrogenotrophic methanogens. Inclusion of additives that facilitate the electron transfer or increase cell proximity of syntrophic species by flocculation can be a suitable strategy to counteract these problems, but its actual impact on syntrophic interactions has yet to be determined. In this study, microbial cultivation and molecular and microscopic analysis were performed to evaluate the impact of conductive (graphene, iron oxide) and non-conductive (zeolite) additives on the degradation rate of acetate and propionate to methane by highly enriched ammonia-tolerant syntrophic cultures derived from a biogas process. All additives had a low impact on the lag phase but resulted in a higher rate of acetate (except graphene) and propionate degradation. The syntrophic bacteria 'Candidatus Syntrophopropionicum ammoniitolerans', Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen were found in higher relative abundance and higher gene copy numbers in flocculating communities than in planktonic communities in the cultures, indicating benefits to syntrophs of living in close proximity to their cooperating partner. Microscopy and element analysis showed precipitation of phosphates and biofilm formation in all batches except on the graphene batches, possibly enhancing the rate of acetate and propionate degradation. Overall, the concordance of responses observed in both acetate- and propionate-fed cultures highlight the suitability of the addition of iron oxide or zeolites to enhance acid conversion to methane in high-ammonia biogas processes. Key points: • All additives promoted acetate (except graphene) and propionate degradation. • A preference for floc formation by ammonia-tolerant syntrophs was revealed. • Microbes colonised the surfaces of iron oxide and zeolite, but not graphene. [ABSTRACT FROM AUTHOR]

A simple solid-state method was developed for large-scale growth of spinel nickel cobaltite (NiCo2O4) nanoparticles on the surface of N-doped reduced graphene oxide nanosheet (N-rGO) as the enhanced performance electrode for electrochemical capacitors. The synthesis involves the room-temperature solid state reaction of a bimetallic (Ni, Co) hydroxide precursor and subsequent thermal transformation to NiCo2O4 nanoparticles on the N-rGO support. Morphological analyses reveal that, with loading rate 49 wt%, NiCo2O4 nanoparticles with an average size of around 12 nm are formed and uniformly dispersed on the surface of N-rGO nanosheets (NiCo2O4/N-rGO). Electrochemical measurements of NiCo2O4/N-rGO composites display a high specific capacitance of 1135 F g− 1 (based on NiCo2O4) at a current density of 1 A g− 1, and excellent cycling performance (100% capacitance retention after 2000 cycles) even at a very high current density of 8 A g− 1, which are significantly higher than that of NiCo2O4 nanoparticles prepared without using N-rGO. This much enhanced electrochemical performance is enabled by both the well-dispersed NiCo2O4 nanoparticles that offer large accessible surface area and the mesoporous structure of NiCo2O4/N-rGO composites that facilitate electrons/ions transport. The facile two-step synthesis process developed in this work is promising to prepare electrode materials for high-performance electrochemical capacitors. [ABSTRACT FROM AUTHOR]

Na3V2(PO4)2F3 has garnered attention as a promising cathode material, primarily due to its substantial theoretical capacity, high operating voltage, and high structural stability. Nonetheless, this material suffers from the low intrinsic electronic conductivity, resulting in a considerable impact on the material properties. To address this challenge, we employ a straightforward hydro-solvothermal reduction process to fabricate Na3V2(PO4)2F3/reduced graphene oxide composites featuring a three-dimensional conductive structure. Through an integrated approach involving material synthesis, structural characterization, and electrochemical analysis, we elucidate the synergistic effects between Na3V2(PO4)2F3 and reduced graphene oxide in facilitating sodium ion storage and transport. The Na3V2(PO4)2F3/reduced graphene oxide cathode in a Na ion cell exhibits reversible capacities of 127 mAh.g−1 at 0.1C and 74 mAh.g−1 at 10C with a 99% retention after 100 cycles at 25 °C. Excellent capacity, reversibility, structure stability, and improved ionic diffusivity make novel composite material an advanced cathode material for sodium-ion batteries, contributing to the development of cost-effective and high-performance energy storage solutions for a sustainable future. [ABSTRACT FROM AUTHOR]

In this study, a label-free electrochemical aptasensor for sensitive detection of aflatoxin B1 (AFB1) was created by using a glassy carbon electrode (GCE) with polyaniline-functionalized graphene oxide (GO-PANI) and gold nanoparticles (AuNPs). Various spectroscopic techniques such as UV–Vis spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Zeta potential, and Raman spectra were employed to analyze the morphology and composition of the GO-PANI-Au nanocomposite, confirming its successful preparation. This aptasensor could be used for the detection of AFB1 with a broad linear range of 0.0001 to 50 ng/mL and a low limit of detection (LOD) of 0.0377 pg/mL under the optimized conditions. Furthermore, the constructed aptasensor displayed remarkable selectivity, repeatability, and stability. To validate the practical usability of our aptasensor, we successfully tested it on millet and corn samples, yielding a satisfactory recovery rate of 98.87–106.10% for AFB1 detection. This outcome highlights the potential application of our methodology in real sample analysis. A highly efficient and sensitive electrochemical aptamer sensor was successfully developed using GO-PANI-AuNPs nanocomposites, and can be used for the detection of AFB1 with good selectivity, repeatability, and stability. [ABSTRACT FROM AUTHOR]

Tetracyclines (TCs) constitute a group of antibiotics that are commonly used to treat bacterial diseases, in veterinary medicine and as an additive in animal feed. This broad application has led to their accumulation in food products and the environment because sewage treatment plants cannot completely remove them. Therefore, the aim of this study was to synthesize graphene oxide (GO) and evaluate its TC adsorption properties in aqueous media. The effects of pH (between 2.5 and 11) and Ca2+ concentration (between 0 and 1 M) were thoroughly investigated. Structural, textural, and electrokinetic properties of the prepared GO were determined by N2 adsorption/desorption, XRD, TEM, UV–vis, FTIR, XPS, thermogravimetry and electrophoretic mobility measurements. TC adsorption on GO is an interplay between the two main roles played by Ca2+: competitor or bridging cation. At low pH, there is cation exchange, and Ca2+ behaves as a competitor of the positively charged TC species, decreasing adsorption as calcium concentration increases. At high, the formation of Ca bridges between the surface and TC (GO-Ca2+-TC) is favored, increasing the adsorption of the antibiotic by increasing calcium concentration. Different combinations of Ca2+ and pH effects are important to improve the use of GO either as a pH-dependent and reversible TC adsorbent for decontamination or as pH-independent adsorbent for TC quantification with electrochemical sensors. [ABSTRACT FROM AUTHOR]

Dynamic adsorption is important for evaluating the Volatile Organic Compounds (VOCs) adsorption performance. During adsorption process, the exothermal characteristic could lead to an increase of the column temperature, which might cause bed combustion and is negative to the adsorption efficiency. In present study, we chose graphene oxide(GO) as adsorbent, comparing with hypercrosslinked polymeric adsorbent(HPA), and conducted the dynamic adsorption experiment of ethanol, n-hexane and cyclohexane at 308 K, 318 and 328 K with different adsorbent column height. The results showed that the temperature had linear and negative influence on breakthrough capacity for three VOCs on two adsorbents. And the breakthrough adsorption capacity of ethanol, n-hexane and cyclohexane on two adsorbents were as follows: ethanol > cyclohexane > n-hexane, closely related with physical parameters of VOCs. But the physical properties of ethanol, n-hexane and cyclohexane have little influence on dynamic adsorption rate in this paper. In addition, for n-hexane and cyclohexane, the breakthrough adsorption capacity on HPA were higher than that on GO, but their k values were similarity on HPA and GO. While for ethanol, the breakthrough capacity and k value on GO were higher than HPA. Most important of all, the negative effect of temperature on VOCs adsorption on GO was lower than HPA. Therefore, GO is a good alternative adsorbent for VOCs recovery. Furthermore, with higher column height, the dynamic adsorption capacity was higher but the adsorption rate was lower. While the influence of temperature on dynamic adsorption capacity and rate were relative independent with column height of adsorbent. [ABSTRACT FROM AUTHOR]

In the present study, we report fabrication of La@Co3O4 and La@CdO with rGO as new materials for NO2 sensing at a temperature range of 30–90 °C. The nanocomposites were characterized using various characterization tools like FTIR, Powder XRD and SEM to determine the composition and morphology of the nanocomposite sensors. The sensing properties such as sensor response, response time and recovery time were measured. The obtained results exhibited that rGO/La@Co3O4 showed a response of 2.9 while rGO /La@CdO is 2.4 at 50 °C. The sensor exhibited high selectivity to NO2, which is explained by a higher affinity for NO2 compared to other environmental pollutant gases like Cl2, NO, H2O and CO. The sensing mechanism was explained by the synergistic effect of reduced graphene with La@Co3O4 and La@CdO. [ABSTRACT FROM AUTHOR]

Fenuron (FEN) is a herbicide that acts as a weed growing inhibitor in crops. Because of its persistence and good solubility in water, its presence in water bodies is emerging as a concern for aquatic species. Herein, we propose a simple development of an electrochemically reduced graphene oxide (rGO) sensor for the monitoring of FEN in environmental water samples. The rGO modified electrode was produced by cyclic voltammetry in a graphene oxide (GO) dispersion under constant stirring. The successfully synthesized rGO showed improved conductivity, electroactive surface area, and faster charge transfer compared to GO and glassy carbon (GC). Scanning electron microscopy images exhibited more frequent wrinkles in the morphology of the reduced form of the carbonaceous material, which is related to a defect-richer structure, as confirmed by Raman spectroscopy. The electrochemical determination of FEN showed the best performance in a 0.1 mol L−1 NaCl solution (pH = 2.5). Optimized parameters in differential pulse voltammetry of FEN resulted in two linear ranges (0.4–12.0 µmol L−1 and 20.0 to 50.0 µmol L−1) with high sensitivities of 6.83 and 1.90 µA µmol−1 L, respectively, and a low LOD of 0.34 µmol L−1. Stability, reproducibility, and interference tests proved the reliability of rGO in sensing FEN in real samples. Spiked tap and canal water samples returned recoveries close to 100%, exhibiting no statistically significant difference when compared to UV-Vis method by an average paired t-test, attesting the viability of the rGO modified electrode as a promising sensor of FEN in environmental water samples. [ABSTRACT FROM AUTHOR]

In this study, a new electrochemical sensor using a glassy carbon electrode modified with graphene oxide (GO) and Zn-doped magnetite Fe3O4 nanosheets is proposed for simultaneous trace determinations of guanine (GA) and adenine (AD). First, graphene oxide nanoparticles were synthesized by the Hammer method, and then UV–Vis, FTIR, and XRD techniques were used to characterize them. The second step involved hydrothermal preparation of Zn-doped magnetite Fe3O4 nanosheets. Different methods, such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer, and energy dispersive X-ray spectroscopy, were utilized to investigate Zn-doped magnetite Fe3O4 nanosheets. The electrochemical behavior of guanine (GA) and adenine (AD) was investigated using different voltammetric techniques, including cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry, and chronoamperometry (CA). It was found that by combining GO with Zn-doped magnetite Fe3O4 nanosheets, the electrochemical sensitivity of the sensor can be improved, and low levels of guanine and adenine can be measured. In a differential pulse voltammetry experiment conducted with this electrode under optimal conditions, such as buffer type, accumulation time, and PH, the electrode showed great sensitivity to both guanine and adenine. The detection limit values were 0.08 and 0.14 µM for GA and AD, respectively. The suggested sensor's performance was tested using human serum as a real sample, and the proposed sensor showed high recovery. As a result of the investigation, it was found that the proposed electrode displayed high sensitivity, good repeatability, and high stability. [ABSTRACT FROM AUTHOR]

Regular monitoring of blood glucose levels is crucial in diabetes management. Commonly used procedures may be invasive and can lead to cross-infection and inflammation. Therefore, a safe, non-invasive blood glucose-monitoring technology is needed. Herein, a 3D reduced graphene oxide (rGO) electrode was modified with MXene (Ti3C2) and gold nanoparticles (AuNPs) to construct a non-invasive, saliva glucose detection electrode. The Au/rGO-Ti3C2 electrode exhibited good detection performance for glucose concentrations in the range of 10 µM–21 mM at a working potential of 0.6 V, with a detection limit of 3.1 µM glucose, and a sensitivity of 355 µA mM−1 cm−2. The Au/rGO-Ti3C2 electrode showed almost no response to the addition of interfering substances, and no effect was observed upon subsequent glucose detection. The sensor could detect glucose in artificial saliva and saliva supernatant. The modified electrode showed a significant response to low glucose concentrations, even at 10 µM. These results indicate the suitability of the Au/rGO-Ti3C2 electrode for saliva glucose detection. The electrode developed in this study has great potential in improving the efficiency of diabetes monitoring through pain-free, non-invasive glucose detection in saliva. [ABSTRACT FROM AUTHOR]

The progress in developing biomaterials for cartilage replacement is still not sufficient, and researchers face the challenge of developing materials that can imitate the physical, chemical, and mechanobiological characteristics of natural cartilage. In this research, the graphene oxide was blended with polyvinyl alcohol/chitosan composite to fabricate composite hydrogels (PVA/Chitosan/GO) using different concentrations of graphene oxide (0, 0.75, 1.5, 2.25, and 3 wt%). The images taken with a scanning electron microscope (SEM) displayed that adding graphene oxide affected the hydrogel structure by reducing the porosity. The composite hydrogel with 3 wt% graphene oxide exhibited the highest compressive strength of 2.15 MPa, and the storage modulus was significantly greater than that of polyvinyl alcohol/chitosan, which satisfied the application requirements. Furthermore, the composite hydrogels displayed excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus bacterial species. They exhibited in vitro cell viability against L929 mouse fibroblasts, which presents the possibility of using composite hydrogel for cartilage regeneration. [ABSTRACT FROM AUTHOR]

A novel L-Arginine-copper complex (L-Arg-Cu) was synthesized regarding the necessity for impeding pathogenic microorganisms with no usage of antibiotics. The L-Arg-Cu complex was immobilized onto the graphene oxide surface (GO/L-Arg-Cu). The Fourier transform infrared and Raman spectroscopies, as well as X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, energy-dispersive X-ray (EDX) spectroscopy, were performed to evaluate the chemical interactions and physical properties of the synthesized compound. To achieve better antimicrobial and wound healing properties of electrospun nanofiber (NF) scaffolds, the GO/L-Arg-Cu composite was loaded in polyvinyl alcohol (PVA). It was attempted to improve the stability and mechanical properties of the fabricated NFs via a heat-induced cross-linkage with citric acid (CA). The SEM images analysis revealed the cross-linked PVA/GO/L-Arg-Cu NFs (PVA/GO/L-Arg-Cu/CA NFs) with an average diameter of 167 nm and smooth surface without any beads. Furthermore, EDX spectroscopy and X-ray mapping showed uniform dispersion of GO/L-Arg-Cu in PVA NFs. The hydrophilicity of NFs was studied by measuring water contact angle (WCA) and degree of swelling. The WCA increased from 17° to 46° for the PVA/CA and PVA/GO/L-Arg-Cu/CA NFs, respectively. The antibacterial activity of the synthesized compounds was explored via Agar diffusion well method. Moreover, the inhibitory of the cross-linked PVA/GO/L-Arg-Cu NFs against bacteria causing wound infections was compared with GO, L-Arginine amino acid, CuO nanoparticles, GO/CuO nanocomposite (NC), GO/L-Arg and their nanofiber scaffolds. The PVA/GO/L-Arg-Cu/CA NFs showed the highest inhibitory zone against Escherichia coli (36 ± 0.34 mm) and Pseudomonas aeruginosa (28 ± 0.25 mm). Besides, the MTT assay on human skin fibroblast (HDF) cells related to the incorporation of copper-L-Arginine complex in nanofiber revealed a high cell viability of over 95%. These results indicated that the PVA/GO/L-Arg-Cu NFs based on an N, O-chelating may have potential application in wound healing. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been used in the range of organic pollutants adsorption and degradation. It's important to improve the performance of GO in the treatment of organic pollutants. Here, we found that the organic pollutants were more efficiently removed in the catalytic degradation of hydrogen peroxide (H2O2) after being pre-adsorbed with GO. The performance of GO in degrading organic pollutants firstly enhanced and then weakened as the treated temperature increases in the air. The adsorption ability of GO for organic pollutants and catalytic activity of H2O2 were highest at 500 ℃, which can be ascribed to the highest oxygen-containing functional groups and the lowest defects on GO after 500 ℃ treatment in the air. This finding will improve the understanding and application of GO in organic pollutants treatment. [ABSTRACT FROM AUTHOR]