Graphene Oxide Nanoplates Research Articles

Green graphene nanoplates for combined photo-chemo-thermal therapy of triple-negative breast cancer.

Aim: Green graphene oxide (GO) nanoplates, which are reduced and stabilized by quercetin and guided by folate receptors (quercetin reduced and loaded GO nanoparticles-folic acid [FA]), were developed to mediate combined photo-chemo-thermal therapy of triple-negative breast cancer. Materials & methods: Modified Hummers method was used for the synthesis of GO followed by its reduction using quercetin, FA was then conjugated as a targeting ligand. A cytotoxicity assay, apoptosis assay and cellular uptake assay were performed in vitro in MDA-MB-231 cell line with and without irradiation of a near-infrared 808nm laser. Results & conclusion: Quercetin reduced and loaded GO nanoparticles-FA showed significantly high cellular uptake (p<0.001) and cytotoxic effects in MDA-MB-231 cells, which was even more prominent under the situation of near-infrared 808nm laser irradiation, making it a potential option for treating triple-negative breast cancer.

New mixed matrix PEI nanofiltration membrane decorated by glycidyl-POSS functionalized graphene oxide nanoplates with enhanced separation and antifouling behaviour: Heavy metal ions removal

Surface functionalization of graphene oxide (GO) nanoplates was performed by glycidyl polyhedral oligosilsesquioxane (POSS), and was used to fabrication of polyetherimide (PEI) based nanofiltration membranes by phase inversion method. The prepared membranes characterized by Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray spectrometry (EDX) and atomic force microscopy (AFM) analysis. The effect of different concentrations of glycidyl POSS-GO (PG) in membrane matrix on separation performance and antifouling property of blended membranes was investigated by contact angle measurement, pure water flux, Na2SO4, Pb(NO3)2, CrSO4 and Cu(NO3)2 rejection and flux recovery ratio. The blended PEI/PG membranes showed significant separation performance and antifouling properties compared with neat PEI and PEI/GO membranes. The highest pure water flux measured 74.77 (L/m2·h) for the blended membrane with 0.001 wt% of PG whereas it was 51.06 (L/m2·h) for the PEI/GO membrane and 17.63 (L/m2·h) for pristine membrane at 4.5 bar pressure. The blended PEI/PG membranes showed outstanding Na2SO4 and Pb(NO3)2, CrSO4, and Cu(NO3)2 rejection compared to blended PEI/GO membranes and neat PEI ones. Furthermore, the highest flux recover ratio (FRR) value was obtained (96%) for the blended [PEI/0.1 %wt PG] membrane whereas FRR was (40%) for PEI/GO and (33%) for the neat PEI membranes.

Efficient removal and fouling-resistant of anionic dyes by nanofiltration membrane with phosphorylated chitosan modified graphene oxide nanosheets incorporated selective layer

To validate the feasibility of designing composite nanofiltration (NF) with separation layer composed of desired both skin features and loose body by one-step process, in this work, a novel phosphorylated chitosan (PCS) NF membrane was fabricated via surface functionalization with an appropriate amount of graphene oxide (GO) nanosheets through forming covalent bonds. It demonstrated superior surface hydrophilicity, roughness and negative charge (decreasing to 41.9°, 18.7 nm and −56.4 mV, respectively), and showed good anionic dye and salt separation performance. Due to the disruption of the packing of polymer chains with the two-dimensional layered rigid GO nanoplates, porosity of its surface layer increased by 16.8 % concurrently. Compared with the bare PCS membrane, the permeate fluxes of NF2 membrane to aqueous solutions dissolved with direct black 38, xylenol orange, ponceau S, NaCl and Na2SO4 under steady state were higher by 58.8 %, 76.3 %, 75.1 %, 83.1 % and 78.8 %, respectively. Also, it exhibited slightly higher anionic dyes and significantly superior salt removal efficiencies. Furthermore, the optimal GO-PCS membrane also exhibited better antifouling property for achieving the outstanding flux decline ratio of 8.67 % and especially irreversible fouling ratio of only 0.17 % to direct black 38.

Spectral and Kinetic Studies of Photochromic Systems Based on Graphene and Graphene Oxide Nanostructures

A comparative spectral and kinetic study of the reactions of thiol-substituted molecules of diarylethene and spirooxazine with graphene nanoparticles and graphene oxide nanoplates has been performed. Differences in the photochromic transformations of compounds that are in contact with the surface of carbon nanoparticles in relation to the structure of the compounds and the nature of the nanoparticles are revealed, which indicates the chemical and physical interaction of the molecules of photochromic compounds with the surface groups of carbon nanostructures.

Effect of graphene oxide nanoplates on the microstructure, quasi-static and dynamic penetration behavior of Al6061 nanocomposites

In this research, the effect of graphene oxide (GO) nanoplates on the microstructure, tensile and perforation behavior of Al6061 matrix has been investigated. The composites with 0.2, 0.5 and 0.8 wt % of GO were fabricated by stir casting and hot rolling process. Optical and scanning electron microscopy observations revealed that the matrix grains are considerably refined by the incorporation of GO nanoplates. The quasi-static tensile tests showed that the grain refinement in the composites gives rise to the accompanied increase in strength and ductility. The penetration tests were carried out using steel flat head projectiles with mass of 4.5 g and initial velocity in range of 100–300 m/s. The experimental as well as the nonlinear simulation results showed that by adding GO nanoplates the ballistic velocity limit of the composite specimens improves by 24% with respect to the base alloy. Also, the energy absorption of composite specimens showed 107% improvement. The experimental data were used to develop an analytical relationship between the weight percent of GO and the deflection of fabricated composites.

New hybrid suspension of MEPCM/GO particles with enhanced dispersion stability and thermo-physical properties

A new type of hybrid suspension comprising microencapsulated phase change material (MEPCM) spheres and graphene oxide (GO) nanoplatelets is proposed. The dispersion stability of the MEPCM/GO suspension was guaranteed by precisely adjusting the density of the MEPCM particles, which had n-heptadecane as the core and hexanediol diacrylate polymer as the shell. The MEPCM particles with excellent monodispersity were fabricated successfully using a co-flowing microfluidic method. The micromorphology of the hybrid MEPCM/GO suspension, measured using a transmission electron microscope, showed that the MEPCM particles and GO nanoplatelets were dispersed uniformly in the base fluid without aggregation. The high dispersity and stability of the hybrid MEPCM/GO suspension provide basic conditions for regulating its thermo-physical properties. Thermal conductivity, specific heat capacity, and viscosity were measured using a laser-flash analysis device, a differential scanning calorimeter, and a rotational rheometer, respectively. The effects of the concentrations of the MEPCM particles and GO nanoplates were investigated. Results showed that enhanced thermal conductivity and specific heat capacity were achieved for the hybrid MEPCM/GO suspension. This advantage of the hybrid suspension became increasingly obvious as the MEPCM and GO concentrations increased. The viscosity of the hybrid MEPCM/GO suspension changed only slightly with the GO concentration, whereas it increased with the MEPCM concentration, and thus showed a relatively good rheological property. The proposed hybrid MEPCM/GO suspension with enhanced thermo-physical properties possesses immense potential for use as a novel working fluid for high-efficiency heat transfer.

Engineering Graphene Wrinkles for Large Enhancement of Interlaminar Friction Enabled Damping Capability.

Graphene nanoplates are hoped-for solid lubricants to reduce friction and energy dissipation in micro and nanoscale devices benefiting from their interface slips to reach an expected superlubricity. On the contrary, we propose here by introducing engineered wrinkles of graphene nanoplates to exploit and optimize the interfacial energy dissipation mechanisms between the nanoplates in graphene-based composites for enhanced vibration damping performance. Polyurethane (PU) beams with designed sandwich structures have been successfully fabricated to activate the interlaminar slips of wrinkled graphene-graphene, which significantly contribute to the dissipation of vibration energy. These engineered composite materials with extremely low graphene content (∼0.08 wt %) yield a significant increase in quasi-static and dynamic damping compared to the baseline PU beams (by 71% and 94%, respectively). Friction force images of wrinkled graphene oxide (GO) nanoplates detected via an atomic force microscope (AFM) indicate that wrinkles with large coefficients of friction (COFs) indeed play a dominant role in delaying slip occurrences. Reduction of GO further enhances the COFs of the interacting wrinkles by 7.8%, owing to the increased effective contact area and adhesive force. This work provides a new insight into how to design graphene-based composites with optimized damping properties from the microstructure perspective.

Toughened Poly(Trimethylene Terephthalate) by Melt Compounding with Functionalized Graphene Oxide Nanocomposites

Functionalized graphene oxide (fGO) nanoplates were added to the Poly (trimethylene terephthalate) (PTT) matrix by melt mixing. The mechanical property and deformation mechanism of PTT/fGO nanocomposites were studied. Addition of a small amount of fGO in PTT improves remarkably tensile properties. The elongation break of PTT/fGO increased with addition of fGO in PTT matrix owing to preferential interaction between groups of fGO and PTT matrix.. The fracture mechanism is identified by scanning electron microscopic (SEM) ananlysis of the fracture surfaces. FGO in PTT/fGO nanocomposites were homogenously dispersed in PTT matrix, indicating that the function of fGO improve the compatibility between PTT and fGO.

Enhancing Morphology and Separation Performance of Polyamide 6,6 Membranes By Minimal Incorporation of Silver Decorated Graphene Oxide Nanoparticles

Nanomaterials can be incorporated in the synthesis of membrane to obtain mixed-matrix membrane with marked improvement in properties and performance. However, stability and dispersion of the nanomaterials in the membrane matrix, as well as the need to use high ratio of nanomaterials for obvious improvement of membrane properties, remain a major hurdle for commercialization. Hence, this study aims to investigate the improvement of polyamide 6,6 membrane properties with the incorporation of silver nanoparticles decorated on graphene oxide (Ag-GO) nanoplates and at the same time focus is given to the issues above. Graphene oxide nanoplates were synthesized using the modified Hummers’ method and decorated with silver before embedded into the polyamide 6,6 matrix. Physicochemical characterizations were conducted on both nanoplates and the mixed-matrix Ag-GO polyamide 6,6 membrane. The issues of Ag agglomeration and leaching were not observed, which could be attributed to the decoration of Ag on GO that helped to disperse the nanomaterials and provided a better anchor point for the attachment of Ag nanoparticles. The synthesized membrane showed marked improvement regarding flux (135% increment) and antifouling (40% lower irreversible fouling), which could be ascribed to the more negative charge of membrane surface (−14 ± 6 to −31 ± 3.8 mV) and hydrophilicity (46% enhancement) of the membranes. With minimal embedment of Ag nanoparticles, the membrane showed superior antibacterial property where the E. coli bacteria could not form a single colony on the membrane surface. Overall, the decoration of Ag on GO nanoplates could be a promising approach to resolve the agglomeration and leaching issues as well as reduce the amount of precious Ag in the synthesis of Ag-GO polyamide 6,6 membrane.

Interactions between HA/GO/epoxy resin nanocomposites: optimization, modeling and mechanical performance using central composite design and genetic algorithm

This study is focused on the role of hydroxyapatite (HA) nanoparticles and graphene oxide (GO) nanoplates on the flexural and compression properties of epoxy-based hybrid nanocomposites. In the first step, epoxy-based hybrid nanocomposites were reinforced by different HA nanoparticles and GO nanoplates up to 7 wt% and 0.5 wt%, respectively. Filler’s weight fractions that used as design parameters have been achieved by central composite design method in Minitab software. The experimental results showed different combinations of HA- and GO-enhanced mentioned mechanical properties in various states. In the second step, a statistical modeling has been done by response surface method (RSM), artificial neural network (ANN) and decision tree methods. Modeling results showed that ANN and decision tree methods have the best fitness. Finally, the mechanical properties are optimized by genetic algorithm. The optimum values are 21.54 MPa for flexural strength in 5.17 wt% HA and 0.38 wt% Go and 25.7 GPa for flexural modulus in 2.73 wt% HA and 0.195 wt% GO. Also, the optimum results for compression strength are 23.95 MPa in 7 wt% HA and 0.289 wt% GO, and also 690.5 MPa for compression modulus in 6.89 wt% HA and 0.007 wt% GO. Effective mechanisms of fillers have been analyzed by SEM and observed that debonding, crack path deflection, plastic void growth and pullout were dominant.

Investigation of the tribological behavior of graphene oxide nanoplates as lubricant additives for ceramic/steel contact

Abstract Effects of graphene oxide nanoplates (GOPs) as lubricant additives on tribological behavior of Si3N4 ceramic/GCr15 steel pairs were investigated, and especially focused on its effects under different rotational speeds and applied loads. Test results demonstrated that Load-carrying capacity, friction reduction and wear resistant were improved by 18.2%,14.7% and 34% with 0.5 wt% GOPs lubrication. Under all tested rotational speeds, GOPs enhanced friction reduction and wear resistance of sliding pairs. Compared to the low applied loads, the tribo-pairs exhibited better tribological properties under high applied loads. The rubbing surfaces were measured by Energy-Dispersive X-ray Spectroscopy and Raman Spectroscopy. The results illustrated that GOPs entered the contact interfaces to prevent tribo-pairs from direct contact, which reduced the materials transfer, friction and wear.

Layer-by-layer self-assembly of reduced graphene oxide on bamboo timber surface with improved decay resistance

Because bamboo is easily attacked by many fungi, and conventional preservatives have many disadvantages including environmental pollution and human health damage, bamboo products should be protected with environmentally friendly methods. Herein, a novel and efficient process for fabrication of antifungal bamboo timber by coating with graphene materials is presented. The crystal phase, morphology, microstructure and other physicochemical properties of the as-prepared samples were characterized by XRD, Raman, SEM, EDX, XPS and FTIR. XRD studies and Raman spectrum confirmed that graphene oxide was reduced to graphene aggregates in the one-step hydrothermal reduction process. SEM images proved that reduced graphene oxide (RGO) nanoplates were deposited on bamboo timber surface by layer-by-layer self-assembly. EDX proved the carbon element composition of RGO coating on the bamboo surface. XPS and FTIR indicated strong interaction of hydrogen bond between bamboo substrate and RGO coating. The anti-fungal activity of bamboo timber with RGO coating was improved significantly when bamboo was infected by Gloeophyllum trabeum and Panerochaete chrysosporium.

Short-term inhalation study of graphene oxide nanoplates

Graphene oxides possess unique physicochemical properties with important potential applications in electronics, pharmaceuticals, and medicine. However, the toxicity following inhalation exposure to graphene oxide has not yet been clarified. Therefore, this study conducted a short-term graphene oxide inhalation toxicity analysis using a nose-only inhalation exposure system and male Sprague–Dawley rats. A total of four groups (15 rats per group) were exposed: (1) control (fresh air), (2) low concentration (0.76 ± 0.16 mg/m3), (3) moderate concentration (2.60 ± 0.19 mg/m3), and (4) high concentration (9.78 ± 0.29 mg/m3). The rats were exposed to graphene oxide for 6 h/day for 5 days, followed by recovery for 1, 3, and 21 days. No significant body or organ weight changes were noted after the short-term exposure or during the recovery period. Similarly, no significant systemic effects of toxicological importance were noted in the hematological assays, bronchoalveolar lavage fluid (BAL) inflammatory markers, BAL fluid cytokines, or blood biochemical assays following the graphene oxide exposure or during the post-exposure observation period. Moreover, no significant differences were observed in the BAL cell differentials, such as lymphocytes, macrophages, or polymorphonuclear cells. Graphene oxide-ingested alveolar macrophages as a spontaneous clearance reaction were observed in the lungs of all the concentration groups from post 1 day to post 21 days. Histopathological examination of the liver and kidneys did not reveal any significant test-article-relevant histopathological lesions. Importantly, similar to previously reported graphene inhalation data, this short-term nose-only inhalation study found only minimal or unnoticeable graphene oxide toxicity in the lungs and other organs.

Self-assembled NiCo2O4-anchored reduced graphene oxide nanoplates as high performance anode materials for lithium ion batteries

The NiCo2O4-anchored reduced graphene oxide (NiCo2O4@rGO) nanoplates have been synthesized by a facile self-assembly process. The morphology, crystalline structure and electrochemical performance of the materials have been investigated comprehensively. The results of SEM manifest that NiCo2O4 particles have been densely anchored on the surface of rGO with a mesoporous structure, and the morphology is tunable via altering concentration of urea during the preparation process. Due to the high ratio of NiCo2O4 in the composite and the plate structure, the electrochemical performance of as-prepared material has been greatly improved. When evaluated as anode materials in lithium ion batteries (LIBs), the as-prepared NiCo2O4@rGO nanocomposite delivers a reversible capacity of 994mAhg−1 at a current density of 200mAg−1 with outstanding rate capability, revealing that it could be a promising anode for LIBs.

Evaluating the ion transport characteristics of novel graphene oxide nanoplates entrapped mixed matrix cation exchange membranes in water deionization

Graphene oxide nanoplates (GONs) embedded mixed matrix polyvinylchloride based heterogeneous cation exchange membranes were prepared by solution casting. The effect of the concentration of GONs on the physico-chemical properties of the membrane was studied. Scanning electron microscopy (SEM) and scanning optical microscopy (SOM) images showed a uniform particle distribution and a uniform surface for the modified membranes. Moreover, the cross-sectional SEM images showed a specific direction for GO nanoplates, perpendicular to the membrane surface. XRD patterns showed that the average particle size of was enhanced by increasing the GONs dosage. The surface hydrophilicity of the membranes was improved, and the water content was lower by increasing the GON content. The IEC of the membranes was enhanced from 1.15 to 1.40meq/g by an increase of the GON concentration up to 0.5wt% in the casting solution, and decreased by a further increase of the content of GONs. The membrane potential, transport number, selectivity and conductivity were improved by utilizing GONs. The ion permeability and flux decreased initially by using GONs up to 0.5wt%, followed by a sharp increasing trend at higher concentrations of GONs.

Tailoring the electrochemical properties of ED ion exchange membranes based on the synergism of TiO2 nanoparticles-co-GO nanoplates

In this paper, the synergetic influence of various weight ratios of TiO2 nanoparticles (NPs)/graphene oxide nanoplates (GONs) in the matrix of ion exchange membranes was examined in order to adapt their electrokinetic properties based on the combination of the high specific surface area of GONs and the antifouling ability of TiO2 nanoparticles. The morphology, physico-chemical features and ionic transport behavior of prepared membranes was studied. Scanning optical microscopy (SOM) and scanning electron microscopy (SEM) images showed a uniform surface for the lab-made membranes relatively. It was found that surface hydrophilicity of the membrane was increased in the presence of GONs and TiO2 NPs. All modified membranes showed a higher water uptake than unmodified membranes. Furthermore, a higher ion exchange capacity, fixed ionic concentration, ionic permeability and flux were observed for all modified membranes in comparison with unmodified membranes. The membrane potential, transport number and selectivity improved in NaCl solutions by using GONs and TiO2 nanoparticles. Furthermore, the membrane ionic conductivity showed an increasing trend by utilizing TiO2-co-GONs NPs. As an overall conclusion, the modified membrane containing 3wt% GONs and 1wt% TiO2 NPs with superior transport number and permselectivity (∼99%), highest current density and cation flux and the lowest areal electrical resistance (∼4–5Ωcm2) showed the best performance.

RGO@APTES/hybrid sol-gel nanocomposite for corrosion protection of 2024 aluminum alloy

Abstract In this work, Graphene Oxide (GO) nanoplates were silanized using 3-aminopropyltriethoxysilane (APTES) and dicyclohexylcarbodiimide (DCC) through carboxylic and epoxide groups to obtain reduced GO (rGO)@APTES nanoplates. The rGO@APTES nanoplates were characterized by SEM, FTIR, and XRD techniques. Much better dispersion of the functionalized nanoplates in the hybrid silane mixture (prepared by equimolar mixing of TEOS and GPTMS) was revealed by visual and TEM images. Afterward, the hybrid sol-gel nanocomposites containing different concentrations of the rGO@APTES nanoplates were applied on Al 2024 substrate. Uniform, dense, defect-free and adherent sol-gel films were obtained in all cases. Decreasing of the water contact angle on the surface was much lower than expected due to removal of the oxygen-containing polar groups in the GO structure. Also, the corrosion behavior of the nanocomposites was evaluated after different immersion times in 3.5 wt.% NaCl solution by EIS measurements. The corrosion resistance of the sol-gel coating was significantly improved after incorporation of the rGO@APTES nanoplates. The sol-gel nanocomposite with 100 ppm rGO@APTES content showed the highest polarization resistance which this concentration was much lower than that reported in similar works. The results obtained by the EIS measurements were confirmed by the visual and microscopic observations after the corrosion tests.

Poly(Vinyl Alcohol)/Graphene Oxide Mixed Matrix Membranes for Pervaporation of Toluene and Isooctane

ABSTRACTPoly(vinyl alcohol)/graphene oxide mixed matrix membranes have been prepared and applied for the pervaporation of isooctane (aliphatic) and toluene (aromatic) mixtures. Characteristics of the membranes such as crystallinity, morphology, and swelling have been investigated, and the results have been used to describe pervaporation performance. Experimental tests evidenced that incorporation of low content of graphene oxide nanoplates (0.5 wt%) in poly(vinyl alcohol) increases affinity of the membrane to aromatics by S and π bonds and selectivity increase to about four times. Moreover, interaction of graphene oxide with toluene results in increasing of swelling and decreasing of permeation flux.

Development of polysulfone-nanohybrid membranes using ZnO-GO composite for enhanced antifouling and antibacterial control

Zinc oxide nanoparticles were well-known for the enhanced antifouling and antibacterial properties which could be beneficial for membrane processes in desalination. The functionalization of ZnO onto graphene oxide nanoplates was targeted for better distribution. Both ZnO and ZnO-GO NPs were synthesized using sol-gel method. The nanoparticles characteristics were checked with XRD, TEM, and FESEM. The nanohybrid membranes were fabricated via wet phase inversion technique and embedded with various percentage of ZnO (1, 2, 3wt%) and ZnO-GO (0.1, 0.3, 0.6wt%) nanoparticles. All the membranes with nanoparticles incorporation exhibited improved membrane properties in comparison with the pristine PSF membrane. The best membrane performance was shown in membrane with 2wt% of ZnO and 0.6wt% of ZnO-GO. These two membranes presented significantly improved performance such as enhanced hydrophilicity, high permeability and porosity, improved humic acid rejection rate as well as good antifouling and antibacterial control. To an extent, the excellent antimicrobial ability of these nanohybrid membranes appeared as appropriate candidate to contribute or overcome bio-fouling issues in applications such as brackish water or seawater desalination. Hence, ZnO and ZnO-GO NPs were superb nanomaterials in the fabrication of PSF-nanohybrid membranes. The use of GO nanoplates allowed reduction of ZnO composition by up to 5 times while showing similar performances.

Fabrication of novel polyethersulfone based nanofiltration membrane by embedding polyaniline-co-graphene oxide nanoplates

Mixed matrix polyethersulfone (PES) based nanofiltration membrane was prepared through phase inversion method by using of polyvinylpyrrolidone (PVP) as pore former and N, N dimethylacetamide (DMAc) as solvent. Polyaniline-co-graphene oxide nanoplates (PANI/GO) were utilized as additive in membrane fabrication. The PANI/GO nanoplates were prepared by polymerization of aniline in the presence of graphene oxide nanoplates. FTIR analysis, scanning electron microscopy (SEM), scanning optical microscopy (SOM), 3D images surface analysis, water contact angle, water content tests, tensile strength tests, porosity tests, salt rejection and flux tests were used in membrane characterization. FT-IR results verified formation of PANI on graphene oxide nanoplates. SOM images showed uniform particles distribution for the mixed matrix membranes. SEM images also showed formation of wide pores for the modified membranes. Water flux showed constant trend nearly by use of PANI/GO in the casting solution. Opposite trend was found for the membrane surface hydrophilicity. Salt rejection was enhanced sharply by utilizing of PANI/GO. The membrane’s tensile strength was improved by increase of PANI/GO concentration. The water content was increased initially by use of PANI/GO nanoplates up to 0.05%wt into the casting solution and then decreased. Membrane porosity was also enhanced by using of PANI/GO nanoplates. Modified membrane containing 0.5%wt PANI/GO nanoplates showed more appropriate antifouling characteristic compared to others.