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Aqueous graphene oxide (GO) suspensions have attracted considerable attention due to their unique properties, which can find numerous applications in various fields, from industry to biomedicine. When designing a GO hydrogel for a specific application, a thorough understanding of the effects of appropriate starting material properties and its concentration range on the suspension stability, structural and rheological properties is of essential importance. The present work is concerned with high solids content (from 1.00 to 2.00 w/v%) GO aqueous suspensions exhibiting marked elastic properties. The effects of the GO particles lateral dimensions and the number of GO layers per particle on the flow and viscoelastic properties are investigated. Rheological parameters useful for quantitative interpretation of the results were obtained by fitting the experimental data using Cross, Herschel-Bulkley, and generalized Maxwell models. All GO suspensions showed a marked shear thinning and thixotropic behaviour with a significant yield stress. Their mechanical spectra confirmed viscoelastic behaviour typical for a suspension in an arrested state. Observed differences in values of rheological parameters and their variations with concentration are explained by particle properties and corresponding rotational restrictions, electrostatic attraction/repulsion, nematic phase formation, and particle agglomeration. The research presents fundamental insights into the rheological properties of GO suspensions, which can be manipulated by varying particle geometry and concentration.

Objetivos: As resinas para impressão 3D em Medicina Dentária apresentam ainda limitações mecânicas. A adição de grafeno pode colmatar esse problema. O objetivo deste trabalho foi avaliar in vitro o efeito do grafeno numa resina de polimetilmetacrilato para impressão 3D ao nível da rugosidade de superfície, propriedades de flexão e dureza. Métodos: Uma resina para impressão 3D foi aditivada com quatro concentrações de grafeno: 0,01wt%, 0,1wt%, 0,25wt% e 0,5wt%. A resina pura foi usada como controlo. A rugosidade de superfície foi medida com um profilómetro de contacto em provetes retangulares (50x10x4mm). A resistência à flexão dos provetes (80x10x4mm) foi calculada usando o teste de flexão em 3 pontos numa máquina de teste universal. A dureza shore D foi medida em provetes circulares (12x6mm) com um durómetro manual. Os resultados foram avaliados utilizando o teste de Kruskal Wallis seguido do teste post-hoc de Bonferroni para comparações entre grupos. Valores de p, Objectives: Commercial photocurable polymers used in dental additive manufacturing still have mechanical limitations. The incorporation of graphene may provide interesting advantages in this field. This study aimed to evaluate in vitro the effect of adding graphene nanoparticles to a 3D-printed polymethylmethacrylate dental resin in terms of surface roughness, flexural properties, and hardness. Methods: A 3D-printed dental resin (Dental Sand, Harz Lab) was loaded with four different graphene nanoplatelet (Graphenest) concentrations: 0.01wt%, 0.1wt%, 0.25wt%, and 0.5wt%. The neat resin was used as the control group. The surface roughness was measured with a contact profilometer using bar-shaped specimens (50x10x4mm). The flexural strength of specimens (80x10x4mm) from each group was calculated using the 3-point bending test in a Universal Test Machine. Hardness shore D was measured using a manual durometer on round-shaped specimens (12x6mm). Data were evaluated using the Kruskall-Wallis test followed by post-hoc Bonferroni corrected pairwise inter-group comparisons. Statistical significance was set at p

Bioparticle concentration can be measured using many techniques, such as mass spectroscopy, light scattering, and fluorescent tracking. Due to some instrument limitations, high cost, low sensitivity-selectivity level, and performance development needs, there is a need to develop a new sensing technique with higher performance. This study used quartz crystal microbalance (QCM) and graphene oxide (GO) as the selective coating materials. For this purpose, two different sensors were tested: uncoated QCM and GO-coated QCM. The sensor performances were tested inside an exposure chamber by exposing the sensors to different bacteria samples: B. pasteurii, B. sphaericus, and B. cereus. The sensor’s frequency shift was counted using a frequency counter, while the sample concentration was measured using a Digital Dust Monitor. The results show that the sensors work well in detecting Bacillus sp. samples with sensitivities of 0.24 to 0.35 Hz.μg-1. The developed sensors have a response time of

Spin-coated blend films with complex phase-separated morphology find broad applications while precise tailoring of the morphology is still challenging. In this study, graphene oxide (GO)-based Janus nanosheets were synthesized by interfacial polymerization in a GO nanosheet stabilized Pickering emulsion with polystyrene (PS) and poly(hydroxyethyl methacrylate) synchronously being grafted to the GO nanosheet from the oil and water sides. The Janus nanosheets make the morphology of spin-coated PS/poly(methyl methacrylate)(PMMA) blend films tunable over the full height of the film until the substrate as their preferential assembly at the PS/PMMA interface and attachment on the glass substrate drive the top PS phase to migrate towards the substrate and the bottom PMMA phase to dewet from the substrate towards the air. By varying blend composition and Janus nanosheet loading, morphologies are readily transformed from a PS network on top of PMMA to PS droplets in the PMMA matrix and from PS encapsulated by PMMA to PMMA cavities in the PS network, etc.. This enables generating thin films with various morphologies ranging from a flat surface to cavity-network structures, droplet-matrix structures or bi-continuous structures, etc. at will. Moreover, the morphologies trapped by jammed nanosheets at the interface are super stable against further evolution upon annealing.

Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. We report a simple, safe, and fast synthesis method to obtain graphene oxide as a functional material for battery-type electrodes. Washing and lyophilization processes were performed to evaluate their effects on exfoliation and removal of functional groups from graphene sheets. Sample GO1 consisted of a 10-layer stack of oxidized graphene, while sample GO2 had 8 stacked layers. The difference between them was an extra washing and lyophilization process in the GO2 sample. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicated an improved specific capacity of 10.15 C.g-1 for GO1 against 4.55 C.g-1 for GO2 at a specific current of 0.5 A.g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, was most likely due to a higher degree of oxygenated groups on its surface, as shown by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) studies.

Mercury ion (Hg(II)) is one of the most prevalent and dangerous heavy metal ions in the environment, and its removal from water sources is a priority for public health and ecosystem conservation policies. Adsorption is a cost-effective and efficient method for removing heavy metal ions from aqueous solutions. In this study, the thiol-functionalized graphene oxide (GO-SH) was synthesized and used for efficient removal of Hg(II) from aqueous solutions. More than 98% of Hg(II) was efficiently removed by GO-SH within 36 h. The Hg(II) removal efficiency by GO-SH treatment was approximately double that by pure GO treatment. The adsorption behavior of Hg(II) on GO-SH was well described by the pseudo-second-order kinetic and the Freundlich isotherm models. Moreover, GO-SH exhibited good stability and reusability in the cycle experiments. Analysis of the adsorption mechanism showed that Hg(II) could be loaded onto the GO-SH surface by reacting with the sulfhydryl groups. This study demonstrates that GO-SH is a promising water purification material with a high efficiency for Hg(II) removal.

L-Dopa, a bioactive compound naturally occurring in some Leguminosae plants, is the most effective symptomatic drug treatment for Parkinson’s disease. During disease progression, fluctuations in L-DOPA plasma levels occur, causing motor complications. Sensing devices capable of rapidly monitoring drug levels would allow adjusting L-Dopa dosing, improving therapeutic outcomes. A novel amperometric biosensor for L-Dopa detection is described, based on tyrosinase co-crosslinked onto a graphene oxide layer produced through electrodeposition. Careful optimization of the enzyme immobilization procedure permitted to improve the long-term stability while substantially shortening and simplifying the biosensor fabrication. The effectiveness of the immobilization protocol combined with the enhanced performances of electrodeposited graphene oxide allowed to achieve high sensitivity, wide linear range, and a detection limit of 0.84 μM, suitable for L-Dopa detection within its therapeutic window. Interference from endogenous compounds, tested at concentrations levels typically found in drug-treated patients, was not significant. Ascorbic acid exhibited a tyrosinase inhibitory behavior and was therefore rejected from the enzymatic layer by casting an outer Nafion membrane. The proposed device was applied for L-Dopa detection in human plasma, showing good recoveries.

Objetivos: Realização de uma revisão sistemática para verificar a alteração do comportamento mecânico do polimetilmetacrilato utilizado em dentária pela adição de grafeno. Métodos: Dois investigadores independentes efetuaram uma pesquisa em três bases de dados (Pubmed/MEDLINE, Web of Science, Embase) até 31 de dezembro de 2021. Realizou-se também uma pesquisa manual para identificar publicações relevantes. A pergunta de investigação definida foi “Em medicina dentária, o polimetilmetacrilato reforçado com grafeno apresenta melhores propriedades mecânicas do que o polimetilmetacrilato convencional?”. A seleção dos artigos seguiu o fluxograma PRISMA, considerando os critérios de inclusão e exclusão definidos. A concordância entre investigadores foi calculada pelo coeficiente Kappa de Cohen. A qualidade dos estudos foi avaliada através da checklist do Joanna Briggs Institute para estudos quasi-experimentais. Resultados: Seis estudos in vitro foram incluídos na análise qualitativa. No total dos estudos analisados nesta revisão foram avaliados 247 provetes, 81 dos quais eram compostos por polimetilmetacrilato convencional e 166 por polimetilmetacrilato aditivado com grafeno. As propriedades mecânicas avaliadas foram: resistência à flexão, módulo de elasticidade, dureza, resistência à flexão biaxial e resistência ao impacto. Maioritariamente, estas propriedades melhoraram com a adição de determinadas concentrações de grafeno. A análise da qualidade dos artigos demonstrou um baixo risco de viés. Conclusões: Considerando as limitações deste estudo, podemos concluir que o grafeno parece melhorar algumas propriedades mecânicas do polimetilmetacrilato utilizado em medicina dentária. No entanto, mais estudos são necessários para se compreender a concentração ideal de grafeno para se obter o melhor desempenho clínico das resinas protéticas., Objectives: To produce a systematic review regarding the effect of graphene-reinforced polymethylmethacrylate used in dentistry on mechanical properties. Methods: Electronic databases (Pubmed/MEDLINE, Web of Science, Embase) were independently searched by two researchers for relevant studies published up to December 2021. An additional manual search was performed to identify relevant publications. The population, intervention, comparison, and outcome (PICO) question was “In dentistry, does graphene-reinforced polymethylmethacrylate offer better mechanical properties than conventional polymethylmethacrylate?”. The selection of articles was carried out according to the established inclusion and exclusion criteria, following the PRISMA flowchart. The inter-investigator reliability was assessed by Cohen's Kappa coefficient. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-experimental Studies. Results: Six in vitro studies were included in the qualitative analysis. A total of 247 specimens were evaluated: 81 made of non-reinforced PMMA resin and 166 of PMMA reinforced with graphene. The mechanical properties evaluated were flexural strength, flexural modulus, hardness, biaxial flexural strength, and impact strength. These properties seem to improve with the addition of graphene in certain concentrations. The analysis of the risk of bias showed low risk. Conclusions: Within the limitation of this study, graphene seems to strengthen some mechanical properties of PMMA dental resin. However, more studies are needed to understand the ideal graphene concentration to improve resin's clinical performance.

During a heart failure, higher amount of nucleoside diphosphate kinase (NDPK) enzyme in the sarcolemma membrane inhibits the synthesis of second messenger cyclic adenosine monophosphate (cAMP), which is required for the regulation of the calcium ion balance for normal functioning of the heart. In a dependent pathway, NDPK normally phosphorylates the stimulatory guanosine diphosphate, GDP(s), to a guanosine triphosphate, GTP(s), on the heterotrimeric (α, β and γ subunits) guanine nucleotide binding protein (G protein), resulting in the stimulation of the cAMP formation. In case of a heart failure, an increased quantity of NDPK also reacts with the inhibitory GDP(i), which is converted to a GTP(i), resulting in the inhibition of the cAMP formation. Typically, the βγ dimer of the G protein binds with hexameric NDPK-B/C complex and receives the phosphate at the residue His266 from residue His118 of NDPK-B. It is known that NDPK-C is required for NDPK-B to phosphorylate the G protein. In this work, the interactions between NDPK-B and NDPK-C are quantified in the presence and absence of graphene oxide (GO) as well as those between NDPK-B and GO through stability analysis involving hydrogen bonds, center of mass (COM), root mean square deviation (RMSD), and salt bridges, and energetics analysis involving van der Waals (VDW) and electrostatic energies. Furthermore, the role of water molecules at the interface of NDPK-B and NDPK-C as well as between NDPK-B and GO is investigated to understand the nature of interactions. It is found that the adsorption of NDPK-B on GO triggers a potential conformational change in the structure of NDPK-B, resulting in a diminished interaction with NDPK-C. This is confirmed through a reduced center of mass (COM) distance between NDPK-B and GO (from 40 A□ to 30 A□) and an increased COM distance between NDPK-B and NDPK-C (from 50 A□ to 60 A□). Furthermore, this is also supported by fewer salt bridges between NDPK-B and NDPK-C, and an increased number of hydrogen bonds formed by the interfacial water molecules. As NDPK-C is crucial to be complexed with NDPK-B for successful interaction of NDPK-B with the G protein, this finding shows that GO can suppress the interactions between NDPK-B/C and G proteins, thereby providing an additional insight into the role of GO in the heart failure mechanism.AUTHOR SUMMARYWe report a novel computational understanding of the interactions between the enzymes NDPK-B and NDPK-C with GO as a potential inhibitor to such interactions and its implications. These types of interactions can play influential roles in many biochemical processes including those that take place during heart failure. A second messenger called cAMP is needed for proper cardiac contraction through the actions of NDPK-B/NDPK-C. It is needed to study the interactions between NDPK-B and NDPK-C to control the synthesis of cAMP. Towards this end, GO is tested through molecular simulations to understand the interactions between NDPK-B and NDPK-C. Influencing or modifying such enzyme active sites has been very less explored and, in this work, the molecular simulations suggest that GO is able to interact with the active site of NDPK-B to provide a sustained cAMP synthesis for longer duration. We found that conformational changes within NDPK-B and NDPK-C influence the interactions between them and such conformational changes are found to be governed by their adsorption on GO. Finally, we found the role of interfacial water molecules between NDPK-B and GO to be crucial in maintaining the interface between them.

The failure of endodontic treatment is directly associated with microbial infection in the root canal or periapical areas. An endodontic sealer that is both bactericidal and biocompatible is essential for the success of root canal treatments. This is one of the vital issues yet to be solved in clinical dental practice. This in vitro study assessed the effectiveness of graphene oxide (GO) composites GO-CaF2 and GO-Ag-CaF2 as endodontic sealer materials. Dentin slices were coated with either the GO-based composites or commonly used root canal sealers (non-eugenol zinc oxide sealer). The coated slices were treated in 0.9% NaCl, phosphate-buffered saline (PBS), and simulated body fluid (SBF) at 37˚C for 24 hours to compare their sealing effect on the dentin surface. In addition, the radiopacity of these composites was examined to assess whether they complied with the requirements of a sealer for good radiographic visualization. Scanning electron microscopy showed the significant sealing capability of the composites as coating materials. Radiographic images confirmed their radiopacity. Mineral deposition indicated their bioactivity, especially of GO-Ag-CaF2, and thus it is potential for regenerative application. They were both previously shown to be bactericidal to oral microbes and cytocompatible with host cells. With such a unique assemblage of critical properties, these GO-based composites show promise as endodontic sealers for protection against reinfection in root canal treatment and enhanced success in endodontic treatment overall.

The addition of graphene has been reported as a potential route for enhancing the thermoelectric performance of SrTiO3. However, the interplay of processing parameters and graphene addition complicates the understanding of this enhancement. Herein, we examine the effects of processing parameters and graphene addition on the thermoelectric performance of La-doped SrTiO3 (LSTO). Briefly, two types of graphene oxide (GO) at different oxidation degrees were used while the LSTO pellets were densified under two conditions with different reducing strength (with/without using oxygen scavenging carbon powder bed muffling). Raman imaging of the LSTO green body and sintered pellets suggests that the added GO sacrificially reacts with the lattice oxygen, which creates more oxygen vacancies and improves electrical conductivity regardless of the processing conditions. The addition of mildly oxidized electrochemical GO (EGO) yields better performance compared with the conventional heavily oxidized chemical GO (CGO). Moreover, we found that muffling the green body with an oxygen scavenging carbon powder bed during sintering is vital to achieve a single-crystal-like temperature dependency of electrical conductivity, implying a highly reducing environment is critical for eliminating the grain boundary barriers. Combining 1.0 wt% EGO addition with a highly reducing environment leads to the highest electrical conductivity of 2102 S cm−1 and power factor of 2452 µW m−1 K−2 at 300 K, with improved average zT value across the operating temperature range of 300 to 867 K. STEM-EELS maps of the optimized sample show a pronounced depletion of Sr and evident deficiency of O and La at the grain boundary region. Theoretical modelling using a two-phase model implies the addition of GO can effectively improve the carrier mobility in grain boundary phase. This work provides guidance for the development of high-performance thermoelectric ceramic oxides.

In this study, graphene oxide and aginate were used to synthesis of nanobiocomposites under different synthesis conditions and the used to investigate the adsorption properties of Th (IV) ions from aqueous solutions. BET surface area, SEM and TEM images, FT-IR spectrometry, XRD techniques were used for the characterization of the adsorbents. In batch adsorption experiments, parameters affecting the adsorption efficiency such as solution pH, contact time, Th (IV) concentration and temperature were investigated using central composite design (CCD). ANOVA (analysis) analysis at the 95% confidence interval of the model applied for the experimental design and the compatibility of this model with the experimental findings were examined. The relevance of the model for the nanobiocomposite prepared by the 1st method is that the P value is F value is 23.77 and 39.45 with the 2nd method, respectively. These results show that the regression for this method is statistically high. The correlation coefficient (R 2), which was 95.69% for the 1st method and 97.36% for the 2nd method, indicates a high coordination between the observed values and the estimated values. According to the CCD results, it has been observed that the main effects of the adsorption process with the materials obtained by the 1st method are in the direction of increasing the concentration, while pH, time and temperature do not have a statistically significant effect. In the adsorption process with the materials obtained by the 2nd method, it was observed that the concentration, time and temperature caused an increasing effect. Langmuir, Freundlich and Dubinin–Radushkevich isotherms were used to determine the adsorption model and the constants related to these isotherms were calculated. In addition, the adsorption process was also investigated in terms of thermodynamics.

Enabling the direct infiltration of freeze-cast graphene structures with water-based ceramic suspensions, otherwise prevented by graphene's intrinsic hydrophobic behaviour, can lead to the production of hierarchical graphene/ceramic composites in a cost-effective and replicable manner. In this study, the addition of a triblock copolymer (PF127) in the formulation of water-based alumina slurries was used to allow the integration with reduced graphene oxide (rGO) scaffolds combining freeze-casting, wet chemistry processing and Spark Plasma Sintering. Wettability and infiltration tests were performed to optimise the composition of the ceramic suspension, leading to the preservation of alignment in embedded rGO scaffolds and maintaining channel widths of 5–15▒μm upon sintering at 1500∘ C., The authors would like to thank the financial support provided by the Engineering and Physical Sciences Research Council (EPSRC: EP/N509449/1) and Cardiff University. We extend the gratitude to the JECS Trust for the award given to attend the 43rd International Conference and Exposition on Advanced Ceramics and Composites (ICACC19) and the Winter Workshop at Daytona Beach, Florida organised by the American Ceramic Society (ACerS). V.G. Rocha would like to thank the Spanish Government (Ramón y Cajal fellowship, RYC2018–024404-I) and the support from the Spanish Research Agency AEI/PID2019–104028RB-100.

Antibiotics are pharmaceutical emerging contaminants (ECs) that contaminate the environment and jeopardize public health. More dangerously, the widespread consumption of antibiotics and their impact on water contamination foster the formation and evolution of antibiotic-resistant genes in microbes. Graphene Oxide (GO) is an emerging carbon material with a great potential to operate as an adsorbent to remove antibiotics from water due to its unique physical and chemical properties. Thus, this study briefly reviews topics related to antibiotic removal from water using GO-based materials. This research also summarizes the benefits of GO structural properties, adsorption mechanisms, and the affinity of the GO synthesis method to the quality of the GO produced.

Graphene oxide (GO)-based membranes have been widely studied for realizing efficient wastewater treatment, due to their easily functionalizeable surfaces and tunable interlayer structures. However, the irregular structure of water channels within GO-based membrane has largely confined water permeance and prevented the simultaneously improvement of purification performance. Herein, we purposely construct the well-structured three-dimensional (3D) water channels featuring regular and negatively-charged properties in the GO/SiO2 composite membrane via in situ close-packing assembly of SiO2 nanoparticles onto GO nanosheets. Such regular 3D channels can improve the water permeance to a record-high value of 33,431.5 ± 559.9 L·m−2·h−1 (LMH) bar−1, which is several-fold higher than those of current state-of-the-art GO-based membranes. We further demonstrate that benefiting from negative charges on both GO and SiO2, these negatively-charged 3D channels enable the charge selectivity well toward dye in wastewater where the rejection for positive-charged and negative-charged dye molecules is 99.6% vs. 7.2%, respectively. The 3D channels can also accelerate oil/water (O/W) separation process, in which the O/W permeance and oil rejection can reach 19,589.2 ± 1,189.7 LMH bar−1 and 98.2%, respectively. The present work unveils the positive role of well-structured 3D channels on synchronizing the remarkable improvement of both water permeance and purification performance for highly efficient wastewater treatment.

Hydrogen peroxide is considered a mild and biocompatible oxidizer, disinfectant, and next-generation of liquid fuels. This study introduces Cobalt-rGO composite with excellent intrinsic activity for oxygen converting to hydrogen peroxide and production of electrochemical energy via a 2-electron mechanism. A good bifunctional catalyst, an economical synthesis method, high specific surface area, a meager metal value, extremely electrochemical durability, and very high selectivity at low temperature are the remarkable properties of Cobalt-rGO composite. Graphite was converted to Graphene-Oxide (GO) using a low temperature process. The oxide groups were then replaced by sulfur atoms to form a Sulfur-rGO composite. Finally, Cobalt phthalocyanine was reacted with Sulfur-rGO at 150 °C. The average pore diameter and SBET were calculated at about 27 nm and 252 m2⋅g−1, respectively. The electrochemical durability test (ΔE1/2 ≈ 0 after 10,000 cycles) and thermal gravimetric analysis were showed high stability due to the rational structure of composite. Elemental analysis has represented the Cobalt and Sulfur content about 3.66% and 3.37%, respectively. The electrons transferred number and Tafel slope were calculated about 2 and 46 mV⋅dec−1 for ORR at room temperature, respectively. The Cobalt-rGO composite is useable in fuel cells and electrochemical processes to produce hydrogen peroxide.

Recent studies showed that nanofluids are considered as a promising way to enhance the heat transfer properties of coolants. Currently, in a car radiator forced convection heat transfer method is carried out to cool circulating fluid. The mixture of water with either ethylene or propylene-glycol is necessary to lower its freezing point and eliminate ice formation. However, the boiling point of deionized water can be pushed up by mixing it with anti-freezing materials like ethylene glycol (EG). Hence the present research work focuses on the heat transfer characteristics of nano-fluids with different combinations of EG and deionized water (60:40, 30:70, and 20:80) along with graphene oxide (GO) nanoparticles (0.1 % wt). The heat transfer potential of graphene oxide/ deionized water-ethylene glycol nanofluids is experimentally investigated in coolant application for car radiators, in which the coolant flow rate is varied from 180 to 420 (LPH) at a fixed coolant temperature of 90 °C. The evaluation of stability is performed using visual inspection and zeta potential test. The density of nanofluid was determined by oscillating U-Tube density meter. The optimized combination of 60% EG, 40% DW and 0.1 wt% GO exhibited higher heat transfer characteristics of the radiator system used. The maximum heat transfer enhancement of 42.77% at 300 LPH, 18.14% at 360 LPH, and 71.1% at 240 LPH for 60:40 EG/DW-based GO nanofluids were obtained. The maximum Nusselt number value of 192 at 420 LPH was observed for 60:40 EG/DW-based GO nanofluid as compared with 20:80, 30:70 EG/DW-based GO nanofluid. It is estimated that by replacing conventional coolant with this nanofluid, reduction in the frontal area of radiator is done which gives more flexibility for industrial design, more eco-friendly vehicle which produces less drag and hence less the fuel cost.

Poly(vinyl alcohol) (PVA)/polyethersulfone (PES) composite membranes were fabricated using two PVA polymers with molecular weights of 50,000 and 15,000 and different crosslinker agents. The membrane with the top layer consisting PVA 50,000 and formaldehyde as the crosslinker were found to have a better separation factor than the others for pervaporative dehydration of isopropanol. While adding 1.0 wt% graphene oxide could represent a better pervaporation separation factor, 248.7% higher than that of the unfilled membrane, treating the graphene oxide nanosheets using cold plasma irradiation under oxygen atmosphere could yield 47.5% higher separation factor compared to the membrane containing untreated nanosheets owing to higher functional groups on the treated nanosheets that enhance the crosslinking density of the membrane. The best plasma treatment conditions in the selected range were found as 60 s irradiation under 0.3 mbar pressure and device power of 25 watts. The superior performance of the optimal membrane fabricated in the present study was confirmed by comparing the values of normalized pervaporation water index with those in previous studies.

Ion exchange membranes, especially cation exchange membranes (CEMs), are an important component in membrane-based energy generation and storage because of their ability to transport cations via the electrochemical potential gradient while preventing electron transport. However, developing a CEM with low areal resistance, high permselectivity, and stability remains difficult. In this study, electrospun graphene oxide/polyethersulfone (GO/PES) composite nanofibers were prepared with varying concentrations of GO. To fabricate a CEM, the pores of the electrospun GO/PES nanofiber substrates were filled with a Nafion ionomer. The pore-filled PES nanofiber loaded with 1% GO revealed a noticeable improvement in hydrophilicity, structural morphology, and mechanical properties. The 1% GO/PES pore-filled CEM was compared to a Nafion membrane of a varying thickness and without a nanofiber substrate. The CEM with a nanofiber substrate showed permselectivity of 85.75%, toughness of 111 J/m3, and areal resistance of 3.7 Ω cm2, which were 12.8%, 4.3 times, and 4.0 times better, respectively, than those of the Nafion membrane at the same thickness. The development of a reinforced concrete-like GO/PES nanofiber structure containing stretchable ionomer-enhanced membrane surfaces exhibited suitable areal resistance and reduced the thickness of the composite membrane without compromising the mechanical strength, suggesting its potential application as a cation exchange membrane in electrochemical membrane-based systems.

In this work, we reported the electrochemical performance of a type of carbon fabric-based supercapacitor by coating MnOx@rGO nanohybrids on carbon fabric with a simple one-step hydrothermal method. We studied the mass ratio of MnOx to rGO on the electrochemical properties of the carbon fabric-based supercapacitors. We found that as the mass ratio is 0.8:1 for MnO@rGO, the supercapacitor with a loading of 5.40 mg cm−2 of MnO@rGO nanohybrids on carbon fabric exhibits a specific capacitance of 831.25 mF cm−2 at 0.1 mA cm−2 current density. It also shows long-term cycling capacitance retention of 97.2% after 10,000 charge–discharge cycles at a current density of 0.4 mA cm−2. We speculate that the high electrochemical performance results from the strong interfacial bonding between the hierarchical architecture of MnO@rGO nanohybrids and carbon fabric.

La ingeniería electrónica está en constante evolución, y la búsqueda de materiales eficientes y versátiles es fundamental para el desarrollo de nuevas tecnologías. Los materiales superconductores son objeto de gran interés debido a su capacidad de transportar corriente eléctrica sin resistencia, lo que los convierte en una herramienta clave para una amplia variedad de aplicaciones en campos como la medicina, la generación de la energía, la computación cuántica y las comunicaciones. En este contexto, el presente trabajo de tesis se centra en la síntesis y caracterización del sistema superconductor de alta temperatura Y3Ba5Cu8O18- -Y358 y su modificación por medio de la sustitución del elemento Itrio (Y) por las dos tierras raras: Praseodimio (Pr) y Europio (Eu). Además, se estudia el efecto del dopaje con Oxido de grafeno (OG) en las muestras de Eu3Ba5Cu8O18- con diferentes concentraciones de OG (0.05% y 0.1%) ya que este material es un excelente conductor eléctrico. Las muestras son sintetizadas empleando el método de Reacción en estado sólido (RES) y se caracterizan estructuralmente mediante la técnica de Difracción de rayos X (DRX) y refinamiento Rietveld a través del programa General Structure Analysis System (GSAS). De esta manera se obtiene la información cristalográfica de los materiales: parámetros de red, estructura cristalina, ángulos, volumen de la celda, grupo espacial, tamaño promedio de cristalitos, porcentaje (%) de las fases cristalográficas y los parámetros de confianza del refinamiento. Así mismo, se examina la microestructura de las muestras por medio de imágenes obtenidas mediante la técnica de Microscopia electrónica de barrido (MEB), donde se evidencia una óptima compactación de los granos cuando las muestras se dopan con OG. Además, se emplea la técnica de Espectrometría de dispersión de energía de rayos X (EDS) para realizar el análisis semicuantitativo de la composición de las muestras, de acuerdo a la fórmula estequiométrica correspondiente a cada elemento químico presente en los materiales. Se mide la resistividad en función de la temperatura, en el rango de 0 a 300 K, donde se observa un decaimiento de la resistividad al alcanzar la Temperatura crítica (Tc) a 49 K. Finalmente, se sugiere la aplicación de la técnica de cuatro puntas para la medición precisa de la resistividad de los materiales. Electronic engineering is constantly evolving, and the search for efficient and versatile materials is fundamental to the development of new technologies. Superconducting materials are the subject of great interest due to their ability to carry electric current without resistance, making them a key tool for a wide variety of applications in fields such as medicine, power generation, quantum computing and communications. In this context, the present thesis work focuses on the synthesis and characterization of the high-temperature superconducting system Y3Ba5Cu8O18- - Y358 and its modification by substituting the Yttrium (Y) element with the two rare earths: Praseodymium (Pr) and Europium (Eu). In addition, the effect of doping with Graphene Oxide (GO) on the samples of Eu3Ba5Cu8O18- with different concentrations of GO (0.05% and 0.1%) is studied, since this material is an excellent electrical conductor. The samples are synthesized using the Solid State Reaction (SSR) method and structurally characterized by the X-ray Diffraction (XRD) technique and Rietveld refinement through the General Structure Analysis System (GSAS) software. In this way, the crystallographic information of the materials is obtained: lattice parameters, crystal structure, angles, cell volume, space group, average size of crystallites, percentage (%) of the crystallographic phases, and the confidence parameters of the refinement. Likewise, the microstructure of the samples is examined through images obtained by the Scanning Electron Microscopy (SEM) technique, where optimum grain compaction is evident when the samples are doped with OG. In addition, the Energy-Dispersive X-ray Spectrometry (EDS) technique coupled to the SEM is used to perform the semi-quantitative analysis of the composition of the samples, according to the stoichiometric formula corresponding to each chemical element present in the materials. The resistivity is measured as a function of temperature, in the range of 0 to 300 K, where a decrease in resistivity is observed when reaching the Critical Temperature (Tc) at 49 K. Finally, the application of the Four-Point Probe technique is suggested for the precise measurement of the resistivity of the materials. Ingeniero Electronico Pregrado

Digital microfluidics, which relies on the movement of drops, is relatively immune to clogging problems, making it suited for micro-reactor applications. Here, graphene oxide paper of 100 μm thickness, fabricated by blade coating sedimented dispersions onto roughened substrates, followed by drying and mechanical exfoliation, was found to be relatively free of cracks and curling. It also exhibited high wettability and elasto-capillary characteristics. Possessing low enough stiffness, it could rapidly and totally self-wrap water drops of 20 μL volume placed 2 mm from its edge when oriented between 0 and 60° to the horizontal. This complete wrapping behavior allowed drops to be translated via movement of the paper over long distances without dislodgement notwithstanding accelerations and decelerations. An amount of 2 drops that were wrapped with separate papers, when collided with each other at speeds up to 0.64 m/s, were found to eschew coalescence. This portends the development of robust digital microfluidic approaches for micro-reactors.

Using renewable photocatalysts for pollutant degradation represents a promising approach to addressing environmental water challenges by harnessing solar energy without additional energy consumption. However, for the practical use of photocatalysts, it is necessary to improve catalyst efficiency, considering cost and biocompatibility. In this study, we developed a new superabsorbent photocatalyst for the degradation of organic dyes in water. Our photocatalyst comprises halloysite nanotubes (HNTs) with a large outer diameter and Si-O and Al-O groups on the outer and inner surfaces, respectively; graphene oxide (GO) possessing numerous sp2 bonds and light-conductive properties; and ZnO, which can degrade organic molecules via a photon source. By exploiting the superabsorbent properties of GOs for organic dyes and stabilizing ZnO nanoparticles on HNTs to inhibit aggregation, our photocatalysts demonstrated significantly improved degradability compared to ZnO nanoparticles alone and combinations of ZnO with HNTs or GO. The structural characteristics of the nanocomposites were characterized using SEM, EDX, Raman spectroscopy, and XRD. Their enhanced photocatalytic activity was demonstrated by the degradation of rhodamine b in water, showing 95% photodegradation under UV illumination for 60 min, while the ZnO nanoparticles showed only 56% dye degradation under the same condition. Additionally, the degradation rate was enhanced by four times. Furthermore, the catalysts maintained their initial activity with no significant loss after four uses, showing their potential for practical implementation in the mass purification of wastewater.

In this study, a conductive composite material, based on graphene oxide (GO), nanocellulose (CNF), and tannins (TA) from pine bark, reduced using polydopamine (PDA), was developed for wound dressing. The amount of CNF and TA was varied in the composite material, and a complete characterization including SEM, FTIR, XRD, XPS, and TGA was performed. Additionally, the conductivity, mechanical properties, cytotoxicity, and in vitro wound healing of the materials were evaluated. A successful physical interaction between CNF, TA, and GO was achieved. Increasing CNF amount in the composite reduced the thermal properties, surface charge, and conductivity, but its strength, cytotoxicity, and wound healing performance were improved. The TA incorporation slightly reduced the cell viability and migration, which may be associated with the doses used and the extract’s chemical composition. However, the in-vitro-obtained results demonstrated that these composite materials can be suitable for wound healing.

Soybean (Glycine max L.) is the most important crop plant in the world. Soil saline-alkali seriously inhibits soybean yield and quality. This study aims to investigate the impact of graphene oxide (GO) and Rhizobium (Rh) on the expression of soybean-related genes as well as the growth and yield under saline-alkali stress. The results show that GO + Rh-treated increased the number of root nodules by 5.43 times compared with the control (Ctrl), the total nitrogen content and root system parameters of plants were also significantly improved. GO + Rh-treated reduced the Na+/K+ ratio and the osmotic substances, while the activities of antioxidant enzymes SOD, POD, CAT and APX in GO + Rh-treated soybean plants increased significantly by 69.18%, 69%, 75.64% and 48.38% compared with the control plants. The REC, MDA and H2O2 content decreased significantly by 46.73%, 42.80% and 43.53%. In addition, GA3 content, among all related saline-alkali hormones, was increased by 100.20% compared with the Ctrl. The expression level of GmGBP1, a key gene for GA3 synthesis, at most increased 6.42 times compared to the Ctrl. The results further reveal that GO + Rh-treated obviously improves the yield traits of soybean plants, which confirms that GO + Rh-treated could be effective in enhancing soybean tolerance to saline-alkali stress. Our findings provide a new strategy for improving the saline-alkali tolerance of soybean, as well as a new perspective for exploiting and utilizing large-area saline-alkali soil.

The development of new biodegradable biomaterials with osteoconductive properties for bone tissue regeneration is one of the urgent tasks of modern medicine. In this study, we proposed the pathway for graphene oxide (GO) modification with oligo/poly(glutamic acid) (oligo/poly(Glu)) possessing osteoconductive properties. The modification was confirmed by a number of methods such as Fourier-transform infrared spectroscopy, quantitative amino acid HPLC analysis, thermogravimetric analysis, scanning electron microscopy, and dynamic and electrophoretic light scattering. Modified GO was used as a filler for poly(ε-caprolactone) (PCL) in the fabrication of composite films. The mechanical properties of the biocomposites were compared with those obtained for the PCL/GO composites. An 18–27% increase in elastic modulus was found for all composites containing modified GO. No significant cytotoxicity of the GO and its derivatives in human osteosarcoma cells (MG-63) was revealed. Moreover, the developed composites stimulated the proliferation of human mesenchymal stem cells (hMSCs) adhered to the surface of the films in comparison with unfilled PCL material. The osteoconductive properties of the PCL-based composites filled with GO modified with oligo/poly(Glu) were confirmed via alkaline phosphatase assay as well as calcein and alizarin red S staining after osteogenic differentiation of hMSC in vitro.

The synthesis of CaCO3/Cu2O/GO nanocomposites was developed by sol-gel auto-combustion method. The analysis of structure was completed on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM). The XRD spectra of the nanocomposites matched the crystal structure of CaCO3/Cu2O. The average crystal size was 20 nm for Cu2O and 25 nm for CaCO3 nanoparticles. FTIR data showed the absorption bands of Cu2O and GO. Raman spectroscopy data confirmed the formation of GO sheets. ESEM micrographs displayed spherical nanoparticles dispersed in GO sheets. X-ray photoelectron spectroscopy showed the peaks of Cu 2p, O 1s, C 1s, Cu 3s, and Ca 2p. The spectra of optical absorption revealed an absorption band of around 450 nm. The calcium content increase led to a decrease in the optical energy gap from 2.14 to 1.5 eV. The production of hydrogen from NaBH4 across the methanolysis reaction was accelerated by the CaCO3/Cu2O/GO nanocomposites. Therefore, these nanocomposites are superior in catalytic hydrogen production systems.

Funding Information: The authors gratefully acknowledge the financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant 05503/2020 , the Canada Excellence Research Chair Program ( CERC-2018-00006 ) and Canada Foundation for Innovation (Project number 38623 ). We acknowledge Ms. Xun Niu for her assistance with mechanical testing, and Ms. Faezeh Bakhshi for help with drawing the schematics. Publisher Copyright: © 2023 Elsevier Ltd We report on the design and synthesis of bio-based, electrically conductive green inks for direct ink writing (DIW) of lightweight electronics and electromagnetic interference (EMI) shields. The inks incorporate fibrillated cellulose and electrochemically synthesized graphene oxide (EGO), with no production and/or consumption of hazardous chemicals. The cellulosic component, TOCNF ((2,2,6,6-tetrame-thylpiperidin-1-yl) oxidanyl (TEMPO)-oxidized cellulose nanofibrils), improves the colloidal dispersion and the rheological properties of EGO-based inks for high-resolution 3D printing via DIW. The printing fidelity and shape retention significantly rely on the EGO/TOCNF loading and ratio in the precursor hydrogel inks. Aerogels result from freeze drying, allowing the production of 3D ultra-lightweight materials with prescribed macro-scale design featuring excellent stability and ease of handling. It is shown that the nano- and micro-scale design of the aerogels can be readily tuned by the solid content and EGO/TOCNF ratio in the inks. This multi-scale materials design provides a unique opportunity to control the mechanical and electrical properties of the printed structures. For instance, aerogels with compression modulus in the range of 250–1096 kPa are obtained based on the composition of the inks. For the optimized ink, an excellent EMI shielding effectiveness, as high as 55.6 dB, is achieved.

Graphene oxide (GO)—branched poly(ethyleneimine) (BPEI) hydrated mixtures were studied by means of fully atomistic molecular dynamics simulations to assess the effects of the size of polymers and the composition on the morphology of the complexes, the energetics of the systems and the dynamics of water and ions within composites. The presence of cationic polymers of both generations hindered the formation of stacked GO conformations, leading to a disordered porous structure. The smaller polymer was found to be more efficient at separating the GO flakes due to its more efficient packing. The variation in the relative content of the polymeric and the GO moieties provided indications for the existence of an optimal composition in which interaction between the two components was more favorable, implying more stable structures. The large number of hydrogen-bonding donors afforded by the branched molecules resulted in a preferential association with water and hindered its access to the surface of the GO flakes, particularly in polymer-rich systems. The mapping of water translational dynamics revealed the existence of populations with distinctly different mobilities, depending upon the state of their association. The average rate of water transport was found to depend sensitively on the mobility of the freely to move molecules, which was varied strongly with composition. The rate of ionic transport was found to be very limited below a threshold in terms of polymer content. Both, water diffusivity and ionic transport were enhanced in the systems with the larger branched polymers, particularly with a lower polymer content, due to the higher availability of free volume for the respective moieties. The detail afforded in the present work provides a new insight for the fabrication of BPEI/GO composites with a controlled microstructure, enhanced stability and adjustable water transport and ionic mobility.

Cardiac tissue engineering is a promising strategy for the treatment of myocardial damage. Mesenchymal stem cells (MSCs) are extensively used in tissue engineering. However, transformation of MSCs into cardiac myocytes is still a challenge. Furthermore, weak adhesion of MSCs to substrates often results in poor cell viability. Here, we designed a composite matrix based on silk fibroin (SF) and graphene oxide (GO) for improving the cell adhesion and directing the differentiation of MSCs into cardiac myocytes. Specifically, patterned SF films were first produced by soft lithographic. After being treated by air plasma, GO nanosheets could be successfully coated on the patterned SF films to construct the desired matrix (P-GSF). The resultant P-GSF films presented a nano-topographic surface characterized by linear grooves interlaced with GO ridges. The P-GSF films exhibited high protein absorption and suitable mechanical strength. Furthermore, the P-GSF films accelerated the early cell adhesion and directed the growth orientation of MSCs. RT-PCR results and immunofluorescence imaging demonstrated that the P-GSF films significantly improved the cardiomyogenic differentiation of MSCs. This work indicates that patterned SF films coated with GO are promising matrix in the field of myocardial repair tissue engineering.

Environmental and human health are seriously threatened by organic dye pollution. Many efforts have been made to find effective and safe methods of eliminating these contaminants. To mitigate these effects, the hydrothermal method was used to effectively generate a ternary kind of Dy2WO6-ZnO embedded in graphene oxide (DWZG) nanocomposites, which were used to degrade the pollutant. Powder X-ray diffraction (XRD) investigation confirms the crystalline character of the as-prepared DWZG nanocomposite. The Dy2WO6-ZnO composition on the graphene oxide (GO) layer is shaped like a combination of algae (Dy2WO6) and clusters (ZnO), as shown by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) investigation revealed the composition of elements and oxidation state of C, Dy, O, W and Zn elements. Methylene blue (MB) was chosen as the organic dye target for photocatalytic degradation using the produced nanocomposites. MB is degraded with a photocatalytic efficiency of 98.2% in about 30 min using a DWZG catalyst. Based on the result of the research entitled “Reactive Oxidative Species,” the primary reactive species involved in the MB degradation are photo-generated •OH and O2•− radicals. The recycle test was also successful in evaluating the catalysts’ long-term viability as well as their reusability.

Recently, resistive random access memory (RRAM) has been an outstanding candidate among various emerging nonvolatile memories for high-density storage and in-memory computing applications. However, traditional RRAM, which accommodates two states depending on applied voltage, cannot meet the high density requirement in the era of big data. Many research groups have demonstrated that RRAM possesses the potential for multi-level cells, which would overcome demands related to mass storage. Among numerous semiconductor materials, gallium oxide (a fourth-generation semiconductor material) is applied in the fields of optoelectronics, high-power resistive switching devices, and so on, due to its excellent transparent material properties and wide bandgap. In this study, we successfully demonstrate that Al/graphene oxide (GO)/Ga2O3/ITO RRAM has the potential to achieve two-bit storage. Compared to its single-layer counterpart, the bilayer structure has excellent electrical properties and stable reliability. The endurance characteristics could be enhanced above 100 switching cycles with an ON/OFF ratio of over 103. Moreover, the filament models are also described in this thesis to clarify the transport mechanisms.

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production of supercapacitor electrodes. In the present work, GO was prepared by the oxidation of graphite recycled from spent Li-ion batteries using mixtures of sulfuric and phosphoric acids (with different H2SO4/H3PO4 ratios), leading to the production of materials with significant S and P contents. These materials were then thermally reduced, resulting in rGO papers that were investigated by solid-state 13C and 31P nuclear magnetic resonance, along with other methods. The electrochemical properties of the produced rGO papers were evaluated, including the recording of cyclic voltammetry and galvanostatic charge–discharge curves, besides electrochemical impedance spectroscopy analyses. The samples obtained by thermal reduction at 150 °C exhibited good rate capability at high current density and high capacitance retention after a large number of charge–discharge cycles. The results evidenced a strong relationship between the electrochemical properties of the produced materials and their chemical and structural features, especially for the samples containing both S and P elements. The methods described in this work represent, then, a facile and low-cost alternative for the production of rGO papers using graphite recycled from spent batteries, with promising applications as supercapacitor electrodes.

To design a new system of novel TEMPO-oxidized cellulose nanofibrils (TOCNs)/graphene oxide (GO) composite, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation was utilized. For the better dispersion of GO into the matrix of nanofibrillated cellulose (NFC), a unique process combining high-intensity homogenization and ultrasonication was adopted with varying degrees of oxidation and GO percent loadings (0.4 to 2.0 wt%). Despite the presence of carboxylate groups and GO, the X-ray diffraction test showed that the crystallinity of the bio-nanocomposite was not altered. In contrast, scanning electron microscopy showed a significant morphological difference in their layers. The thermal stability of the TOCN/GO composite shifted to a lower temperature upon oxidation, and dynamic mechanical analysis signified strong intermolecular interactions with the improvement in Young’s storage modulus and tensile strength. Fourier transform infrared spectroscopy was employed to observe the hydrogen bonds between GO and the cellulosic polymer matrix. The oxygen permeability of the TOCN/GO composite decreased, while the water vapor permeability was not significantly affected by the reinforcement with GO. Still, oxidation enhanced the barrier properties. Ultimately, the newly fabricated TOCN/GO composite through high-intensity homogenization and ultrasonification can be utilized in a wide range of life science applications, such as the biomaterial, food, packaging, and medical industries.

The historical stone heritage that we inherit must be passed on to future generations, not only in the same conditions that we found it but, if possible, in better ones. Construction also demands better and more durable materials, often stone. The protection of these materials requires knowledge of the types of rocks and their physical properties. The characterization of these properties is often standardized to ensure the quality and reproducibility of the protocols. These must be approved by entities whose purpose is to improve the quality and competitiveness of companies and to protect the environment. Standardized water absorption tests could be envisaged to test the effectiveness of certain coatings in protecting natural stone against water penetration, but we found that some steps of these protocols neglect any surface modification of the stones, and hence may not be completely effective when a hydrophilic protective coating (i.e., graphene oxide) is present. In this work, we analyze the UNE 13755/2008 standard for water absorption and propose alternative steps to adapt the norm for use with coated stones. The properties of coated stones may invalidate the interpretation of the results if the standard protocol is applied as is, so here we pay special attention to the characteristics of the coating applied, the type of water used for the test, the materials used, and the intrinsic heterogeneity of the specimens.

A nitrocellulose–graphene oxide hybrid that consists of a commercially nitrocellulose (NC) membrane non-covalently modified with graphene oxide (GO) microparticles was successfully prepared for oligonucleotide extraction. The modification of NC membrane was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), which highlighted the principal absorption bands of both the NC membrane at 1641, 1276, and 835 cm−1 (NO2) and of GO in the range of 3450 cm−1 (CH2-OH). The SEM analysis underlined the well-dispersed and uniform coverage of NC membrane with GO, which displayed thin spider web morphology. The wettability assay indicated that the NC–GO hybrid membrane exhibited slightly lower hydrophilic behavior, with a water contact angle of 26.7°, compared to the 15° contact angle of the NC control membrane. The NC–GO hybrid membranes were used to separate oligonucleotides that had fewer than 50 nucleotides (nt) from complex solutions. The features of the NC–GO hybrid membranes were tested for extraction periods of 30, 45, and 60 min in three different complex solutions, i.e., an aqueous medium, an α-Minimum Essential Medium (αMEM), and an αMEM supplemented with fetal bovine serum (FBS). The oligonucleotides were desorbed from the surface of the NC–GO hybrid membrane using Tris-HCl buffer with a pH of 8.0. Out of the three media utilized, the best results were achieved after 60 min incubation of the NC–GO membranes in αMEM, as evidenced by the highest fluorescence emission of 294 relative fluorescence units (r.f.u.). This value corresponded to the extraction of approximately 330–370 pg (≈7%) of the total oligo-DNA. This method is an efficient and effortless way to purify short oligonucleotides from complex solutions.

Reinforced concrete structures in the marine environment face serious corrosion risks. Coating protection and adding corrosion inhibitors are the most economical and effective methods. In this study, a nano-composite anti-corrosion filler with a mass ratio of CeO2:GO = 4:1 was prepared by hydrothermally growing cerium oxide on the surface of graphene oxide. The filler was mixed with pure epoxy resin at a mass fraction of 0.5% to prepare a nano-composite epoxy coating. The basic properties of the prepared coating were evaluated from the aspects of surface hardness, adhesion grade, and anti-corrosion performance on Q235 low carbon steel subjected to simulated seawater and simulated concrete pore solutions. Results showed that after 90 days of service, the corrosion current density of the nanocomposite coating mixed with corrosion inhibitor was the lowest (Icorr = 1.001 × 10−9 A/cm2), and the protection efficiency was up to 99.92%. This study provides a theoretical foundation for solving the corrosion problem of Q235 low carbon steel in the marine environment.

Graphene oxide (GO) properties make it a promising material for graphene-based applications in areas such as biomedicine, agriculture, and the environment. Thus, its production is expected to increase, reaching hundreds of tons every year. One GO final destination is freshwater bodies, possibly affecting the communities of these systems. To clarify the effect that GO may impose in freshwater communities, a fluvial biofilm scraped from submerged river stones was exposed to a range (0.1 to 20 mg/L) of GO concentrations during 96 h. With this approach, we hypothesized that GO can: (1) cause mechanical damage and morphological changes in cell biofilms; (2) interfere with the absorption of light by biofilms; (3) and generate oxidative stress, causing oxidative damage and inducing biochemical and physiological alterations. Our results showed that GO did not inflict mechanical damage. Instead, a positive effect is proposed, linked to the ability of GO to bind cations and increase the micronutrient availability to biofilms. High concentrations of GO increased photosynthetic pigment (chlorophyll a, b, and c, and carotenoids) content as a strategy to capture the available light more effectively as a response to the shading effect. A significant increase in the enzymatic (SOD and GSTs activity) and low molecular weight (lipids and carotenoids) antioxidant response was observed, that efficiently reduced oxidative stress effects, reducing the level of peroxidation, and preserving membrane integrity. Being complex entities, biofilms are more similar to environmental communities and may provide more accurate information to evaluate the impact of GO in aquatic systems.

Paper has gained popularity as a packaging material due to its reduced environmental impact compared with non-degradable alternatives. However, its flammability poses safety risks, prompting research on enhancing its flame retardancy. This work introduces a diffusion-driven self-assembly strategy (DDSAS) to create a functional graphene oxide (GO) coating on various packaging papers. DDSAS involves infiltrating the paper’s cellulose microfiber network with branched polyethyleneimine (b-PEI), which binds firmly to cellulose microfibers. Electrostatic interactions between GO and b-PEI then drive GO assembly into a densely stacked, layered structure on the paper surface. This GO structure provides a physical barrier against flames and generates incombustible gases (CO2, H2O, NO2, and NO) when heated, diluting the surrounding oxygen concentration and acting as a heat insulation layer. These factors increase the flame retardancy of treated papers ten-fold. Additionally, the gradual reduction of GO upon heating forms reduced graphene oxide (rGO) on the paper, significantly increasing its electrical conductivity. As a result, the flame-retardant papers not only prevent the fire from spreading but can also act as fire sensors by triggering an alarm signal at the early stages of contact with fire. In summary, this work offers a rational strategy for designing and manufacturing flame-retardant paper packaging materials.

The aim of this study was to determine the bactericidal potential of graphene oxide (GO) in contact with four species of bacteria: E. coli, S. mutans, S. aureus and E. faecalis. Bacterial cell suspensions of each species were incubated in a medium containing GO, with incubation times of 5, 10, 30 and 60 min, at final concentrations of 50, 100, 200, 300 and 500 μg/mL. The cytotoxicity of GO was evaluated using live/dead staining. The results were recorded using a BD Accuri C6 flow cytofluorimeter. Obtained data were analyzed using BD CSampler software. A significant bacteria viability reduction was noted in all GO-containing samples. The antibacterial properties of GO were strongly influenced by GO concentration and incubation time. The highest bactericidal activity was observed at concentrations of 300 and 500 μg/mL for all incubation times (5, 10, 30 and 60 min). The highest antimicrobial potential was observed for E. coli: after 60 min, the mortality rate was 94% at 300 µg/mL GO and 96% at 500 µg/mL GO; the lowest was found for S. aureus—49% (300 µg/mL) and 55% (500 µg/mL).

To improve the wear resistance of polyimide (PI), surface modification was developed. In this study, the tribological properties of graphene (GN), graphene oxide (GO), and KH550-grafted graphene oxide (K5-GO) modified PI were evaluated by molecular dynamics (MD) at the atomic level. The findings indicated that the addition of nanomaterials can significantly enhance the friction performance of PI. The friction coefficient of PI composites decreased from 0.253 to 0.232, 0.136, and 0.079 after coating GN, GO and K5-GO, respectively. Among them, the K5-GO/PI exhibited the best surface wear resistance. Importantly, the mechanism behind the modification of PI was thoroughly revealed by observing the wear state, analyzing the changes of interfacial interactions, interfacial temperature, and relative concentration.

Polymer/graphene nanocomposites have attracted significant attention from the research community over the past two decades. In this work, nanocomposites of polystyrene-co-acrylonitrile (SAN) and graphene oxide (GO) were prepared using a solution blending method with tetrahydrofuran as the solvent. The GO loadings used were 0.1, 0.25, 0.5, and 1.0 wt.%. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy were employed to characterize the structure and morphology of SAN/GO nanocomposites. Thermal analysis showed increases in the glass transition (Tg) and peak thermal degradation (Tdpeak) temperatures of SAN by the additions of GO, with Tg increasing by 3.6 °C and Tdpeak by 19 °C for 1.0 wt.% GO loading. Dynamic mechanical analysis revealed that the storage modulus of SAN was also enhanced with the incorporations of GO by up to 62% for 1.0 wt.% loading. These property enhancements may be attributed to a good dispersion of GO in the polymer matrix and their interfacial interactions.

Water pollution caused by emerging contaminants such as pharmaceutical compounds is a growing problem worldwide. In this reported work, graphene oxide (GO) was directly used to remove an antihistamine drug, cetirizine. GO was prepared from graphite using a modified Hummer’s method and was characterized by UV–vis spectroscopy, Fourier-transformed infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), field scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), etc. GO was demonstrated to be a highly efficient adsorbent for removing cetirizine from an aqueous solution. The adsorption of cetirizine on GO at various pH levels showed that in acidic pH with the adsorption shows faster kinetics and complete removal of cetirizine within 10 min, followed by neutral pH, which showed relatively slower kinetics but complete removal of cetirizine. However, at basic pH, GO could not completely remove cetirizine after 24 h. At a neutral pH, GO showed maximum adsorption of 81.30 mg g−1 of cetirizine. The adsorption isotherm results showed good agreement with the Langmuir isotherm. The BET surface area analysis showed the presence of mesoporosity in GO. In addition, the BET analysis further revealed a type IV isotherm curve being followed. A plausible mechanism is also discussed in the paper. The recyclability experiment demonstrates an adsorption efficiency of 85% after four cycles. The thermodynamic study reveals that adsorption is thermodynamically less favorable at higher temperatures. Hence, the current study successfully demonstrates the use of GO as an efficient adsorbent in removing cetirizine. It also studies the various factors and interactions affecting adsorption. Thus, this study sheds light on the adsorption characteristics of cetirizine on graphene oxide.

Presently, water pollution poses a serious threat to the environment; the removal of organic pollutants from resources, especially dyes, is very important. Nanofiltration (NF) is a promising membrane method to carry out this task. In the present work, advanced supported poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) membranes were developed for NF of anionic dyes using bulk (the introduction of graphene oxide (GO) into the polymer matrix) and surface (the deposition of polyelectrolyte (PEL) layers by layer-by-layer (LbL) technique) modifications. The effect of PEL combinations (polydiallyldimethylammonium chloride/polyacrylic acid (PAA), polyethyleneimine (PEI)/PAA, and polyallylamine hydrochloride/PAA) and the number of PEL bilayers deposited by LbL method on properties of PPO-based membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. Membranes were evaluated in NF of food dye solutions in ethanol (Sunset yellow (SY), Congo red (CR), and Alphazurine (AZ)). The supported PPO membrane, modified with 0.7 wt.% GO and three PEI/PAA bilayers, exhibited optimal transport characteristics: ethanol, SY, CR, and AZ solutions permeability of 0.58, 0.57, 0.50, and 0.44 kg/(m2h atm), respectively, with a high level of rejection coefficients—58% for SY, 63% for CR, and 58% for AZ. It was shown that the combined use of bulk and surface modifications significantly improved the characteristics of the PPO membrane in NF of dyes.

The alternative antibacterial treatment photothermal therapy (PTT) significantly affects oral microbiota inactivation. In this work, graphene with photothermal properties was coated on a zirconia surface using atmospheric pressure plasma, and then the antibacterial properties against oral bacteria were evaluated. For the graphene oxide coating on the zirconia specimens, an atmospheric pressure plasma generator (PGS-300, Expantech, Suwon, Republic of Korea) was used, and an Ar/CH4 gas mixture was coated on a zirconia specimen at a power of 240 W and a rate of 10 L/min. In the physiological property test, the surface properties were evaluated by measuring the surface shape of the zirconia specimen coated with graphene oxide, as well as the chemical composition and contact angle of the surface. In the biological experiment, the degree of adhesion of Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) was determined by crystal violet assay and live/dead staining. All statistical analyzes were performed using SPSS 21.0 (SPSS Inc., Chicago, IL, USA). The group in which the zirconia specimen coated with graphene oxide was irradiated with near-infrared rays demonstrated a significant reduction in the adhesion of S. mutans and P. gingivalis compared with the group not irradiated. The oral microbiota inactivation was reduced by the photothermal effect on the zirconia coated with graphene oxide, exhibiting photothermal properties.

A dispersive micro-solid phase extraction (Dµ-SPE) method for the preconcentration of trace metal ions (Pb, Cd, Cr, Mn, Fe, Co, Ni, Cu, Zn) on graphene oxide with the complexing reagents neocuproine or batocuproine is presented here. Metal ions form cationic complexes with neocuproine and batocuproine. These compounds are adsorbed on the GO surface via electrostatic interactions. The factors affecting the separation and preconcentration of analytes such as pH, eluent (concentration, type, volume), amount of neocuproine, batocuproine and GO, mixing time, and sample volume were optimized. The optimal sorption pH was 8. The adsorbed ions were effectively eluted with 5 mL 0.5 mol L−1 HNO3 solution and determined by the ICP-OES technique. The preconcentration factor for the GO/neocuproine and GO/batocuproine in the range 10–100 and 40–200 was obtained for the analytes, with detection limits of 0.035–0.84 ng mL−1 and 0.047–0.54 ng mL−1, respectively. The method was validated by the analysis of the three certified reference materials: M-3 HerTis, M-4 CormTis, and M-5 CodTis. The procedure was applied to determine metal levels in food samples.

9 figures, 2 tables.-- Supplementary information available., Concern for the perpetuation of stone monuments is deeply ingrained in humans; however, despite the attempts made in this field, there is still a great deal of effort needed to bring about advancements in the conservation of ornamental stone. Erosive agents, such as rain, extreme temperatures, and chemical and biological agents, threaten our stone heritage and gradually wear away buildings, sculptures, and other monuments found all around the world. Limestone and dolostone have been widely used throughout history, given their ease of extraction and workability. Nevertheless, these properties make them particularly vulnerable to the aforementioned erosive agents, for which the main solution at present is costly and time-consuming restoration. Given the scarcity of effective and durable agents to prevent the deterioration of ornamental and heritage stones, and as graphene oxide (GO) has recently shown impressive effectiveness for this task, this work will further explore the viability of GO as a protective coating for monumental dolostone. For this purpose, GO is sprayed over dolostone surfaces by water dispersion with no adjuvants. The coating performance is assessed in terms of thermal stress, optical inspection (structured light 3D scanner), colorimetry, leachate analysis, and electron microscopy. The main results show that spray-coated GO over stone surfaces creates a highly protective and durable barrier without altering their aesthetic qualities., This research received funding from the University of León (ULE-PoC 2018) and Fundación General de la ULE y de la Empresa (FGULEM) under projects 2019/00149/001 and 2020. This research was also funded through an awarded MICINN project (PID2020-120439RA-I00). The authors are also thankful to the “Applied innovation against climate change and other aggressions on stone monuments (PRESERVARTE)” project of the Regional Ministry of Culture and Tourism of Castilla y León, which will be used to complement this research in the future.

Graphene oxide nanomaterials have been developed for wide-ranging applications, but has potential safety concerns for human health. Controlled inhalation exposures in human volunteers have been a vital means to determine the effects and mechanisms of ultrafine particles in air pollution, however, few studies have used this approach to explore the effects of nanomaterials. We conducted a double-blind randomised controlled study to determine whether inhalation of graphene oxide affects pulmonary or cardiovascular function. A high purity graphene oxide was synthesised with a thickness of 1-2 layers in two sizes: ‘small’ (lateral dimensions: 100-1700 nm) and ‘ultrasmall’ (30-500 nm). Graphene oxide particles at 200 µg/m3, or filtered air, were inhaled for 2 hours by 14 young healthy volunteers on repeated visits, with measurement of cardiorespiratory parameters before and across 4 hours after exposure. Graphene oxide exposure was well-tolerated with no adverse effects. Heart rate, blood pressure, lung function and inflammatory markers were unaffected by graphene oxide irrespective of particle size. GO did not change blood biomarkers of coagulation, however, there was a mild increase in thrombus formation in an ex vivo model of arterial injury. Proteomics revealed very few differential plasma proteins. Overall, acute inhalation of graphene oxide was not associated with overt detrimental effects in healthy humans. These findings demonstrate the feasibility of carefully controlled human exposures for risk assessment of graphene nanomaterials.