Graphene Oxide Nanomaterials Research Articles

Study on friction properties of polydopamine modified graphene oxide as lubricant additive

In this study, polydopamine-modified graphene oxide (PGO) nanomaterials were prepared based on the self-polymerization of dopamine in a weakly alkaline environment. In the friction experiment, the lubricants with 0.15 wt% PGO nanomaterials have optimal friction properties. Subsequently, X-ray photoelectron spectroscopy (XPS), X-ray energy spectroscopy (EDS), and laser Raman spectroscopy were performed on the wear scar. Compared to pure oil, the friction coefficient was reduced by 31%, and the trace width was reduced by 47.69%. In addition, molecular dynamics simulations showed that PGO has the lowest diffusion coefficient among n-hexadecane and the interaction energy between PGO and n-hexadecane molecules was the largest, and oil droplets containing PGO exhibited the best adsorption performance on the surface of the Si3N4/GCr15. The results showed that compared with other additives, PGO as a lubricant additive can play a significant role in reducing friction and anti-wear.

MOFs-Graphene Composites Synthesis and Application for Electrochemical Supercapacitor: A Review.

Today’s world requires high-performance energy storage devices such as hybrid supercapacitors (HSc), which play an important role in the modern electronic market because supercapacitors (Sc) show better electrical properties for electronics devices. In the last few years, the scientific community has focused on the coupling of Sc and battery-type materials to improve energy and power density. Recently, various hybrid electrode materials have been reported in the literature; out of these, coordination polymers such as metal-organic frameworks (MOFs) are highly porous, stable, and widely explored for various applications. The poor conductivity of classical MOFs restricts their applications. The composite of MOFs with highly porous graphene (G), graphene oxide (GO), or reduced graphene oxide (rGO) nanomaterials is a promising strategy in the field of electrochemical applications. In this review, we have discussed the strategy, device structure, and function of the MOFs/G, MOFs/GO, and MOFs/rGO nanocomposites on Sc. The structural, morphological, and electrochemical performance of coordination polymers composites towards Sc application has been discussed. The reported results indicate the considerable improvement in the structural, surface morphological, and electrochemical performance of the Sc due to their positive synergistic effect. Finally, we focused on the recent development in preparation methods optimization, and the opportunities for MOFs/G based nanomaterials as electrode materials for energy storage applications have been discussed in detail.

Effect of Graphene Oxide on the Low-Temperature Crack Resistance of Polyurethane-SBS-Modified Asphalt and Asphalt Mixtures.

In this study, the novel nanomaterial graphene oxide (GO) was added as a modifier to polyurethane–styrene-butadiene-styrene (SBS)-modified asphalt, and a graphene oxide/polyurethane/SBS composite-modified asphalt mix was prepared. The effect of the graphene oxide material on the low-temperature crack resistance of the asphalt and mixes was investigated by bending beam rheometer (BBR) tests, beamlet bending tests at different low temperatures, and characterization by scanning electron microscopy for its microscopic condition. OpenCV image processing was used to visually represent the low-temperature cracking of the mix. The results of the BBR tests showed that the incorporation of graphene oxide resulted in a reduction in creep stiffness S and an increase in creep rate m compared with the control asphalt. The best improvement in the low-temperature cracking resistance of the polyurethane/SBS-modified asphalt was achieved at 0.5% GO doping. The results of the small beam flexural tests showed that graphene oxide as a modifier improved the flexural strength and flexural strain of the mix, resulting in a mix with a lower stiffness modulus and a better relaxation stress capacity with the addition of graphene oxide, which is also expressed through the OpenCV images. Graphene oxide significantly improved the low-temperature crack resistance of polyurethane-SBS-modified asphalt and its mixes. As a new type of nanomaterial-modified asphalt, graphene oxide/polyurethane/SBS composite-modified asphalt shows promising applicability in cold zone roads.

Immobilization of Air-Stable Copper Nanoparticles on Graphene Oxide Flexible Hybrid Films for Smart Clothes.

Through the use of organic/inorganic hybrid dispersants—which are composed of polymeric dispersant and two-dimension nanomaterial graphene oxide (GO)—copper nanoparticles (CuNPs) were found to exhibit nano stability, air-stable characteristics, as well as long-term conductive stability. The polymeric dispersant consists of branched poly(oxyethylene)-segmented esters of trimellitic anhydride adduct (polyethylene glycol−trimethylolpropane−trimellitic anhydride, designated as PTT). PTT acts as a stabilizer for CuNPs, which are synthesized via in situ polymerization and redox reaction of the precursor Cu(CH3COO)2 within an aqueous system, and use graphene oxide to avoid the reduction reaction of CuNPs. The results show that after 30 days of storage the CuNPs/PTT/GO composite film maintains a highly conductive network (9.06 × 10−1 Ω/sq). These results indicate that organic/inorganic PTT/GO hybrid dispersants can effectively maintain the conductivity stability of CuNPs and address the problem of CuNP oxidation. Finally, the new CuNPs/PTT/GO composite film was applied to the electrocardiogram (ECG) smart clothes. This way, a stable and antioxidant-sensing electrode can be produced, which is expected to serve as a long-term ECG monitoring device.

Green synthesis of graphene oxide polysulfone membrane using dimethyl sulfoxide as green solvent

Membrane technology has been widely used in various industries such as medical, food, pharmaceutical, and wastewater treatment industries. It is known as a remarkable green technology owing to its low energy consumption, small footprint and easy to be scale up. However, the usage of conventional solvent has been reported to bring undesirable impacts to the environment and public health. In view of these, green solvent namely dimethyl sulfoxide (DMSO) was used along with polysulfone (PSf) polymer and graphene oxide (GO) nanomaterials to a form a new generation mixed matrix membrane (MMM). A series of membranes were fabricated through the immersion precipitation method by varying the GO concentration from 0.0 wt% to 2.0 wt% at fixed polymer and solvent weight ratio. The fabricated membrane was characterized by contact angle, porosity, and average pore size while the performance of the membrane was evaluated through the pure water flux measurement, rejection study, and flux recovery ratio. The presence of the GO in the membrane has substantially enhanced the membrane performance in terms of hydrophilicity and pure water flux associated with the hydrophilic nature of GO. The optimal membrane performance was found at 0.5 wt% of GO nanomaterials whereby it demonstrated approximately three times increment of water flux from 28.95 L/m2·hr to 76.14 L/m2·hr while maintaining a slightly better humic acid rejection which improved by 9.55% from 48.88% to 53.55% and 13.13% enhancement in membrane hydrophilicity. At the same times, it also demonstrated great antifouling properties with a high flux recovery rate up to 96.25%.

Graphene oxide nanomaterials in the recovery of shoulder joint movement contraction

Graphene oxide nanomaterials in the recovery of shoulder joint movement contraction

Graphene oxide nanomaterials in the recovery of shoulder joint movement contraction

Graphene oxide nanomaterials in the recovery of shoulder joint movement contraction

Preparation and characterization studies of nano graphene oxide

Recently, graphene oxide has received a lot of attention due to its unique chemical and physical properties. In this work, graphene oxide nanoparticles were produced using a chemical peeling technique. Graphene Oxide (GO) films with two-dimensional structure were successfully prepared via the modified hummer method. X-ray diffraction was chosen to measure the crystal structure of the graphene oxide nano powder. A Fourier transform infrared (FTIR) spectrum analyzer was used to confirm the presence of oxygenated functional groups. The thermal stability of graphene oxide nanomaterial was estimated to be 450 °C from TGA. This exceptional thermal stability of these graphene oxides is important in the application in the areas related to the solar energy conditions of transparent film composite materials and biomedical applications.

Synthesis of Graphene Oxide Via Microwave Assisted Eco-Friendly Method Versus Modified Hummer Method

Using eco-friendly chemicals, a unique method for synthesizing graphene oxide (GO) by microwave radiation along with organic solvents is described. Microwave radiation was utilized to cause the graphite worm to expand significantly in all directions.SEM images were used to assess the morphology and structure of GO nanomaterials. X-ray diffraction, UV-Vis, and Fourier-transform infrared spectroscopies were used to identify the oxygenated groups on the GO surface. When compared to the conventional Hummer’s technique, the new microwave-assisted approach significantly reduces reaction time and is much more eco-sustainable. Aside from being environmentally sustainable, the suggested approach has the appealing feature of producing a large number of graphene nano-sheets quickly. This article compares efficient and environmentally microwave-assisted and conventional modified hummer methods for graphene oxide preparation..

Anti-microbial and methylene blue dye adsorption properties of cotton fabrics modified with TiO2, Fe, Ag-doped TiO2, and graphene oxide nanomaterials

Nanoparticle materials have received increasing attention in the functional modification of textiles. In this work, pure TiO2, Ag-doped TiO2, Fe-doped TiO2, and graphene oxide nanoparticles were used to impart the anti-bacterial and adsorptive properties of nanoparticles to cotton fabric. The treated fabric materials were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The obtained treated fabrics were used as adsorbents for the removal of methylene blue from aqueous solution. The functionalized cotton fabrics were tested for their anti-microbial capability against Escherichia coli, Bacillus cereus, and Candida albicans. All the functionalized fabrics have higher anti-microbial activity compared to untreated cotton, especially the fabrics containing silver and Fe-doped TiO2. The optimum conditions of the adsorption process are determined via the study of the effect of the initial concentration of dye, pH, and contact time on the removal efficiency. Langmuir, Freundlich, and Temkin isotherms are applied for the equilibrium adsorption data. GO-Cot and Ag-Ti@GO-Cot samples showed the highest adsorption removal activity. The linear correlation coefficient ( R2) showed that the Temkin model well fitted the data of adsorption in the GO-Cot sample. The analysis of experimental data with different kinetic models showed that the pseudo-second-order kinetic model well fitted the adsorption data better than the other kinetic models of the pseudo-first-order, Elovich, and intra-particle diffusion.

Enhanced Photothermal and Photoacoustic Performance of Graphene Oxide in NIR-II Biowindow by Chemical Reduction

We report on a novel strategy for constructing graphene oxide nanomaterials with strongly enhanced photothermal (PT) and photoacoustic (PA) performance in the near-infrared (NIR)-II biowindow by chemical reduction. Optical spectra clearly reveal that obvious enhancement of optical absorption is observed in the whole NIR wideband from the NIR-I to NIR-II region for chemically reduced graphene oxide (CR-G) nanomaterials, which is mainly arising from the restoration of the electronic conjugation within the graphene oxide sheets and therefore inducing a black-body re-introduction effect of typical graphite-like materials. We experimentally synthesized CR-G samples with different degrees of reduction to demonstrate the efficiency of the proposed strategy. Experimental results show that the PT performance of the CR-G samples is greatly improved owing to the absorption enhancement by chemical reduction in the NIR-II biowindow. Furthermore, both in vitro and in vivo PA imaging of the CR-G samples with different degrees of reduction are performed to demonstrate their enhanced NIR-II PA performances. This work provides a feasible guidance for the rational design of graphene oxide nanomaterials with great potential for PT and PA applications in the NIR-II biowindow by chemical reduction.

Lighting up Individual Organelles With Fluorescent Carbon Dots.

Cell organelles play crucial roles in the normal functioning of an organism, therefore the disruption of their operation is associated with diseases and in some cases death. Thus, the detection and monitoring of the activities within these organelles are of great importance. Several probes based on graphene oxide, small molecules, and other nanomaterials have been developed for targeting specific organelles. Among these materials, organelle-targeted fluorescent probes based on carbon dots have attracted substantial attention in recent years owing to their superior characteristics, which include facile synthesis, good photostability, low cytotoxicity, and high selectivity. The ability of these probes to target specific organelles enables researchers to obtain valuable information for understanding the processes involved in their functions and/or malfunctions and may also aid in effective targeted drug delivery. This review highlights recently reported organelle-specific fluorescent probes based on carbon dots. The precursors of these carbon dots are also discussed because studies have shown that many of the intrinsic properties of these probes originate from the precursor used. An overview of the functions of the discussed organelles, the types of probes used, and their advantages and limitations are also provided. Organelles such as the mitochondria, nucleus, lysosomes, and endoplasmic reticulum have been the central focus of research to date, whereas the Golgi body, centrosome, vesicles, and others have received comparatively little attention. It is therefore the hope of the authors that further studies will be conducted in an effort to design probes with the ability to localize within these less studied organelles so as to fully elucidate the mechanisms underlying their function.

Graphene oxide nanosheet-mediated fluorescent RPA “turn-on” biosensor for rapid RNAi transgenic plant detection

In this paper preliminarily verified that graphene oxide (GO) nanomaterials enhanced the recombinase polymerase amplification (RPA). GO nanosheets improved the efficiency of RPA amplification by absorbing ingredients to induce local aggregation. The recombinase initially aggregated with the primers to form nucleoprotein filaments, absorbed on the GO nanosheets, changing the structure. Therefore, an isothermal fluorescence biosensor was developed based on GO nanosheets enhanced the RPA to detect RNA interference (RNAi) transgenic plants. FAM-labeled primers were absorbed and quenched by the GO nanosheets. After amplification, the primers were extended into double-stranded DNA, detaching from the GO surface to recover the fluorescent signal. The biosensor displayed high sensitivity and selectivity and showed an excellent relationship ranging from 1.5 to 100 ng of genome DNA, with a detection limit (LOD) of 1.5 ng. Consequently, the biosensor provides an enhanced isothermal method for detecting genetically modified (GM) products and exhibits significant potential for molecular detection.

Graphene oxide doped ethanol droplet combustion: Ignition delay and contribution of atomization to burning rate

Effects of graphene oxide nanomaterials addition and oxidation level on ignition delay and burning rate of ethanol droplets are experimentally investigated. Three graphene oxide samples are synthesized and characterized. Separate high-speed OH* chemiluminescence and high-speed shadowgraphy images are collected. The results suggest that increasing the loading concentration from 0 to 0.1% (by weight) generally increases the ignition delay, except for ethanol doped with the highly oxidized graphene. The results show that unlike pure ethanol droplets, atomization may occur for the doped ethanol droplets. It is demonstrated that, independent of the tested conditions, atomization occurs in the second half of the droplet lifetime. The probability density function of the atomized baby droplet diameter, initial projected velocity, and length of the projected trajectory are similar for all tested conditions and independent of the oxidation level and loading concentration of the additives. The joint probability density function calculated for the atomization-related parameters against one another suggests that the majority of the baby droplets feature a relatively short lifetime, indicating they may potentially burn inside the flame envelope. Using droplet surface regression curves versus time, the burning rate for periods in which the atomization does not occur, and for the periods that the atomization is present are estimated. The former burning rate is shown to enhance by increasing the loading concentration and reducing the oxidation level of graphene. However, supported by Fourier-Transform Infrared spectroscopy of the graphene oxide samples, it is found that a maximum increase in the latter burning rate for both loading concentrations occurs for ethanol doped with the graphene oxide that features maximum amount of infrared radiation absorption. To quantify the effect of atomization on the droplet mass loss, a conservation of mass framework is utilized, and it is shown that relatively intense atomization suppresses the droplet evaporation mass loss. Doping ethanol with graphene oxide and increasing the loading concentration from 0.01 to 0.1% enhances the overall burning rate, with a maximum enhancement of 8.4% pertaining to addition of reduced oxidized graphene oxide and for the loading concentration of 0.1%.

Applying Artificial Neural Network and Response Surface Method to Forecast the Rheological Behavior of Hybrid Nano-Antifreeze Containing Graphene Oxide and Copper Oxide Nanomaterials

In this study, the efficacy of loading graphene oxide and copper oxide nanoparticles into ethylene glycol-water on viscosity was assessed by applying two numerical techniques. The first technique employed the response surface methodology based on the design of experiments, while in the second technique, artificial intelligence algorithms were implemented to estimate the GO-CuO/water-EG hybrid nanofluid viscosity. The nanofluid sample’s behavior at 0.1, 0.2, and 0.4 vol.% is in agreement with the Newtonian behavior of the base fluid, but loading more nanoparticles conforms with the behavior of the fluid with non-Newtonian classification. Considering the possibility of non-Newtonian behavior of nanofluid temperature, shear rate and volume fraction were effective on the target variable and were defined in the implementation of both techniques. Considering two constraints (i.e., the maximum R-square value and the minimum mean square error), the best neural network and suitable polynomial were selected. Finally, a comparison was made between the two techniques to evaluate their potential in viscosity estimation. Statistical considerations proved that the R-squared for ANN and RSM techniques could reach 0.995 and 0.944, respectively, which is an indication of the superiority of the ANN technique to the RSM one.

The lipid composition of few layers graphene and graphene oxide biomolecular corona

Among all the biomolecules that form the corona of nanomaterials, lipids are somehow the less studied and characterized. In the present paper, we report on the first investigation of the lipid content of the biomolecular corona formed around few layers graphene (FLG) and graphene oxide (GO) nanomaterials. Our work revealed that significantly different lipid signatures are associated with each of the two materials and that the biocorona formed in human plasma around FLG and GO is enriched or depleted in specific lipids. We also investigated if the presence of individual lipids in the corona, like sphingomyelins and triacylglycerols, might play a role in the uptake of these two materials in a blood-brain barrier cellular model.

Using graphene oxide to improve physical property and control ASR expansion of cement mortar

Alkali-silica reaction (ASR) is a slowly occurring reaction in concrete between alkaline pore solution and reactive non-crystalline silica in aggregates, which is a challenge to physical property and durability of concrete. The oxygen-containing functional groups coupled with large surface area of graphene oxide (GO) nanomaterial renders highly reactive interaction with cement-based composite. Here, the physical properties and ASR expansion test of cement mortars modified with varied loadings of GO (wGO) or/and Pyrex glass (GOPM) were implemented after optimizing GO dispersion efficiency in water. The water absorption and microstructures of GOPM were observed to figure out the mechanism of GO’s effect on mechanical strength, permeability, and ASR expansion of GOPM. Results show, 15 kJ is the optimal sonication energy for the dispersion of 300 mL pristine GO-water suspension with 0.04% wGO; the effect of GO on improving the flexural and compressive strength of GOPM is remarkable, the maximal amplitude is up to 24.16%, 43.03% compared with the baseline, respectively; GO has great influence on long-term anti-permeability and controlling expansion, the nano-nucleation and interlocking effect of GO render the expansion rate of GOPM be well below 0.1% threshold.

Pro-inflammatory response and genotoxicity caused by clay and graphene nanomaterials in A549 and THP-1 cells

Nanoclays and graphene oxide nanomaterials represent a class of materials sharing similar shapes constituted of high aspect ratio platelets. The increased production of these materials for various industrial applications increases the risk of occupational exposure, consequently with elevated risk of adverse reactions and development of pulmonary diseases, including lung cancer. In this study, pro-inflammatory responses and genotoxicity were assessed in alveolar epithelial cells (A549) and activated THP-1 macrophages (THP-1a) after exposure to three nanoclays; a pristine (Bentonite) and two surface modified (benzalkonium chloride-coated Nanofil9, and dialkyldimethyl-ammonium-coated NanofilSE3000); graphene oxide (GO) and reduced graphene oxide (r-GO) nanomaterials. The pro-inflammatory response in terms of IL-8 expression was strongest in cells exposed to Bentonite, whereas surface modification resulted in decreased toxicity in both cell lines when exposed to Nanofil9 and NanofilSE3000. GO and r-GO induced a pro-inflammatory response in A549 cells, while no effect was detected with the two nanomaterials on THP-1a cells. The pro-inflammatory response was strongly correlated with in vivo inflammation in mice after intra-tracheal instillation when doses were normalized against surface area. Genotoxicity was assessed as DNA strand breaks, using the alkaline comet assay. In A549 cells, an increase in DNA strand breaks was detected only in cells exposed to Bentonite, whereas Bentonite, NanofilSE3000 and GO caused an increased level of genotoxicity in THP-1a cells. Genotoxicity in THP-1a cells was concordant with the DNA damage in bronchoalveolar lavage fluid cells following 1 and 3 days after intra-tracheal instillation in mice. In conclusion, this study shows that surface modification of pristine nanoclays reduces the inflammatory and genotoxic response in A549 and THP-1a cells, and these in vitro models show comparable toxicity to what seen in previous mouse studies with the same materials.

Impact of Polyethylene Glycol Functionalization of Graphene Oxide on Anticoagulation and Haemolytic Properties of Human Blood.

Graphene oxide (GO) is one of the most explored nanomaterials in recent years. It has numerous biomedical applications as a nanomaterial including drug and gene delivery, contrast imaging, cancer treatment, etc. Since most of these applications need intravenous administration of graphene oxide and derivatives, the evaluation of their haemocompatibility is an essential preliminary step for any of the developed GO applications. Plentiful data show that functionalization of graphene oxide nanoparticles with polyethylene glycol (PEG) increases biocompatibility, thus allowing PEGylated GO to elicit less dramatic blood cell responses than their pristine counterparts. Therefore, in this work, we PEGylated graphene oxide nanoparticles and evaluated the effects of their PEGylation on the structure and function of human blood components, especially on the morphology and the haemolytic potential of red blood cells (RBCs). Further, we studied the effect of PEGylation on some blood coagulation factors, including plasma fibrinogen as well as on the activated partial thromboplastin (aPTT), prothrombin time (PT) and platelet aggregation. Our findings provide important information on the mechanisms through which PEGylation increases GO compatibility with human blood cells. These data are crucial for the molecular design and biomedical applications of PEGylated graphene oxide nanomaterials in the future.

Synthesis and Application of the Magnetic Nanocomposite GO-Chm for the Extraction of Benzodiazepines from Surface Water Samples Prior to HPLC-PDA Analysis

Nowadays, the interest in preparing new, cheap and simple adsorbents that are used in sample preparation is on the rise. Graphene oxide (GO) nanomaterials and nanocomposites have become increasingly popular due to the novel methods of syntheses that have been published. Owing to their vast specific surface area and their π-delocalized electron system they possess, they are appropriate for the adsorption of a variety of aromatic organic compounds, being utilized either as adsorbents in analytical methods or as filter materials for the removal of pollutants in water. Pharmaceutical compounds, such as benzodiazepines, end up in surface waters caused by consumption or their disposal through sewage, thus becoming pollutants. In the present study, an analytical method has been developed and validated for the determination of two model-analytes of benzodiazepines by HPLC-DAD and their sample preparation protocol which consists of the Stir bar magnetic solid phase extraction (SB-MSPE) method, evaluating therefore the nanocomposite material as a decent adsorbent. The separation took place with the usage of an analytical column C18 RP-HPLC in 10 min. For the alprazolam (ALP) and the flunitrazepam (FLT), the LODs and LOQs were 3 ng/mL and 10 ng/mL, respectively, while the relative recoveries ranged between 93.6–112.9% and the RSDs were 1.11–9.50%. Finally, the material was examined for its reusability and was found that it can be used for over eight cycles of extraction/elution.