Different Concentrations Of Graphene Oxide Research Articles

Effect of Graphene Oxide Nanoparticles Incorporation on the Mechanical Properties of a Resin-Modified Glass Ionomer Cement.

The objective of this study was to evaluate the effect of incorporating different concentrations of graphene oxide (GO) nanoparticles on the mechanical properties of a resin-modified glass ionomer cement (RMGIC). A commercial RMGIC (Resiglass R, Biodinâmica) was modified by incorporating 0.1% and 0.5% (by weight) of GO into the powder's material. An unmodified RMGIC was used as a control group. Powder samples were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Specimens were fabricated and subjected to flexural strength (n = 15), modulus of elasticity (n = 15), Vicker's microhardness (n = 10), and surface roughness tests (n = 10). Data were analyzed using one-way ANOVA and Tukey's post hoc test (α = 5%). Experimental groups' powder demonstrated a homogeneous dispersion of GO. No statistically significant difference was observed in flexural strength (p = 0.067) and modulus of elasticity (p = 0.143) tests. The groups containing 0.1% and 0.5% GO showed significantly higher microhardness and lower surface roughness values (p < 0.001) compared to the control group. The incorporation of GO nanoparticles at concentrations of 0.1% and 0.5% improved the microhardness and surface roughness without negatively affecting the flexural strength and modulus of elasticity of an RMGIC.

Synthesis and electrochemical characterizations of RGO-decorated MnO2 nanorods/carbon cloth-based wearable symmetric supercapacitors

The current research explores a facile two-step method for fabricating flexible RGO-decorated MnO2 nanorod electrodes on a carbon cloth substrate, ideal for wearable energy storage devices. The strategy involves first depositing MnO2 nanorods on the carbon cloth utilizing a hydrothermal technique, followed by a simple ex-situ decoration with reduced graphene oxide by varying concentrations. Through comprehensive physical and electrochemical analyses, the impact of different concentrations of graphene oxide on the physical and electrochemical characteristics of MnO2 electrodes is thoroughly examined. Among the investigated concentrations of graphene oxide, the RGO-decorated MnO2 electrode featuring a 20 mg/100ml concentration of graphene oxide showcased the maximum specific capacitance reaching 1072.28 F/g at a 5 mV/sec in a 1M Na2SO4 electrolyte. Furthermore, this electrode demonstrated commendable long-term cycle stability, preserving over 87% of its original capacitance after enduring 2000 cycles of charge and discharge. A symmetric prototype supercapacitor device has been constructed to assess their practical utility utilizing symmetric electrodes and an aqueous electrolyte. This symmetric device exhibits promising electrochemical properties, underscoring the potential of the developed electrodes for real-world implementation. The remarkable structural, morphological, and electrochemical characteristic attributes of RGO-decorated MnO2 nanorods grown on the carbon cloth substrate position them as superior electrode materials tailored for the burgeoning realm of wearable energy storage devices, paving the way for advanced flexible and efficient energy storage solutions.

Development of a graphene oxide/hydroxyapatite-containing orthodontic primer: An in-vitro study

Fixed orthodontic appliances increase the risk of enamel demineralization and the development of white spot lesions (WSLs). This study aimed to develop a novel orthodontic primer that incorporates graphene oxide (GO) and hydroxyapatite (HA), investigate their cell viability, bonding strength, and enamel damage, and evaluate their antibacterial and remineralization properties. Nine groups were prepared by adding different concentrations of GO (0.1, 0.25, and 0.5 wt%) and HA (2, 5, and 7 wt%) to Transbond™ XT orthodontic primer. After observing the surface morphology of the material by a Field Emission Scanning Electron Microscope (FESEM), the phase of the materials by X-ray diffraction (XRD), and their chemical compositions by Energy Dispersive X-ray spectroscopy (EDX). The prepared primers were compared to the control primer group in terms of cell viability, shear bond strength (SBS), adhesive remnant index (ARI), enamel damage index (EDI), and antibacterial test. Then the groups with higher antibacterial properties (GOHA 0.1–2, GOHA 0.1–5, GOHA 0.25–2) were selected to evaluate their remineralization properties. Primers with all the prepared concentrations of GO/HA revealed acceptable cell viability levels within the limit of the ISO standards with comparable SBS and ARI values with the control primer (p > 0.05). Simultaneously, the EDI significantly reduced, and the antibacterial properties enhanced when compared to the control group (p < 0.05). The result of remineralization properties revealed that the selected groups had significantly higher remineralization ability than the control group which was more pronounced in GOHA 0.25–2 group. All the prepared orthodontic primers with different concentrations of GO/HA are safe biologically with adequate SBS, ARI, and EDI values for clinical application with enhanced antibacterial properties. The GOHA 0.25–2 experimental primer reveals the best antibacterial and remineralization properties which require further in-vitro and in-vivo investigation as a preventive measure of WSL.

Effect of Graphene Oxide and Ammonia-modified Graphene Oxide Particles on ATPase Activity of Rat Liver Mitochondria

Graphene and its derivatives have become promising materials for biomedical applications in the last decade. Before their widespread application, however, evaluating their toxicity and mechanisms underlying interactions with cellular components is imperative. Aims: Assessment of the effect of two graphene derivatives, pristine graphene oxide (GO) and ammonia-modified GO (GO-NH2) particles, on the ATPase activity of rat liver mitochondria and ROS production. Methods: Liver mitochondria were isolated from male albino rats and treated with different concentrations of GO and GO-NH2 particles (4, 10, 25, and 50 μg/ml). ATPase activity of both, intact and uncoupled by freezing/thawing mitochondria was determined by the measurement of inorganic phosphate (Pi) released from ATP. The generation of hydrogen peroxide (H2O2) after exposure of mitochondria to GO and GO-NH2 particles was determined by a DCFH-D assay. Results: GO and GO-NH2 particles applied at concentrations of 4 and 50 μg/ml did not affect the ATPase activity of intact mitochondria. In contrast, in uncoupled mitochondria, they demonstrated a stimulating effect on ATPase activity. The impact of GO-NH2 was more substantial and concentration-dependent. ROS production was also higher in GO-NH2-treated mitochondria. Conclusion: The present study demonstrated that GO and GO-NH2 particles can exert a cytotoxic effect on mitochondria even after a short-time of exposure to both types of particles.

Cellulose acetate scaffold containing hydroxyapatite/graphene oxide nanocomposite by electrospinning for advanced regenerative therapies

The aim of this study was to synthesize and characterize Cellulose Acetate (CA) porous scaffolds using the electrospinning technique associated with Hydroxyapatite (HA) and different concentrations of graphene oxide (GO), for advanced regenerative therapies application. The scaffolds were categorized into four distinct groups based on their composition: (1) Pure CA scaffolds; (2) CAHA scaffolds; (3) CAHAGO 1.0% scaffolds; (4) CAHAGO 1.5% scaffolds. Transmission Electron Microscopy (TEM) was used for the characterization of the nanocomposite. The scaffolds were analyzed by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), and in vitro cell viability assays (WST). For the biological test analysis of Variance (two-way) was used, followed by Tukey’s post-test (α = 0.05). The TEM analysis allowed for the visualization of the deposition of HA on the graphene sheets, confirming the synthesis of the nanocomposite. XRD revealed the predominant presence of CaP phases in the CAHA, CAHAGO 1.0%, and CAHAGO 1.5% groups, underscoring the inherent mineral composition of the scaffolds. FTIR demonstrated cellulose characteristics and PO4 bands in the groups containing HA, confirming the effective incorporation of this material. Raman spectroscopy revealed distinct peaks in the GO groups, conclusively verifying the successful integration of graphene into the scaffold matrix. The micrographs showcased irregular pores filling the entire surface, arising from the intricate overlapping of fibers during scaffold formation. Importantly, all scaffolds exhibited excellent cell viability in the conducted assays. A proliferation process was observed in CAHA and CAHAGO 1.5% groups after 48 h ( p &lt; 0.05). In conclusion, the scaffolds synthesized hold significant promise in the realm of tissue engineering and provide a fresh perspective on the possibilities for regenerative therapies.

Effects of Graphene Oxide on Tribological Properties of Micro-Arc Oxidation Coatings on Ti-6Al-4V

This paper investigates the effect of graphene oxide (GO) particles on the friction reduction and wear resistance of coatings on a Ti-6Al-4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations of GO were added in aluminate–phosphate electrolyte. The composition of the MAO coatings was investigated using X-ray diffraction and the energy dispersive spectrum. Measurements of the coating’s thickness, hardness, and roughness have also been conducted. Ball-on-disk friction tests under dry conditions were carried out to reveal the tribological behavior of the MAO coating. The results showed that the coating consisted of Al2TiO5 and γ-Al2O3. The addition of GO greatly reduced the friction coefficient by 25%. The coating with 5 g/L of GO particles exhibited the lowest friction coefficient (reduced from 0.47 to 0.35). Moreover, the coating thickness become thicker (from 10 to 20 μm) with an increase in GO concentration from 0 to 10 g/L. The wear mechanism was revealed via worn surface analysis. This study provides a helpful way to improve the surface wear resistance of titanium alloys.

Graphene oxide decreases the effects of salt stress on Persian clover seed germination

ABSTRACT Among biotic and abiotic stresses, the most restrictive for plant distribution is salt stress, where different concentrations might exert harmful effects on seed germination. Recently, nanomaterials were used successfully to mitigate these stresses, indicating that plants may be able to develop normally in adverse conditions. The aim of this study was to examine the effects of graphene oxide (GO) on the germination of Persian clover seedlings under salt stress conditions. Following sown on substrate paper, seeds were tested after exposure to different concentrations of graphene oxide (0, 125, 250, or 500 mg L−1 GO), sodium chloride (0; −0.1; −0.2; −0.3, or −0.4 MPa NaCl) and/or GO + salt concomitantly, and then stored for 7 days in a germination chamber at 20°C in the presence of light. Seed germination and growth parameters of seedlings were determined. Graphene oxide demonstrated protective effect against salt stress as evident by no marked adverse effects on seed germination where GO blocked the salt-induced reduction in germination. The results obtained provide references for the safe application of nanomaterials and emphasize the significance of GO as a promising material for reducing the toxicity of salts in agriculture.

Effect of graphene oxide nanoparticles on in vitro growth of Fragaria x ananassa (Cameron Highlands white Strawberry) and evaluation of genetic stability using DAMD and ISSR markers

Graphene oxide (GO) is a novel nanomaterial with distinct physical properties and significant biological applications. The use of GO in plant tissue culture offers several new properties and potential applications. This research is vital due to the growing need for innovative techniques to promote plant growth, improve plant productivity and mitigate challenges posed by environmental stressors. This study focused on the rare Cameron Highlands white strawberry plants (Fragaria x ananassa) and addressed issues such as callus production during direct shoot induction and hyperhydricity. The research aimed to investigate the effects of GO on the regeneration process and genetic stability of white strawberry plants and to use molecular markers to ensure that plants propagated in vitro are true to type. For this purpose, shoot tip explants were used and different concentrations of GO (0, 2.5, 5.0, 7.5, 10 mg/L) were added to the Murashige and Skoog (MS) medium for six weeks. The results showed that the optimum concentration for promoting the development of white strawberry seedlings was 7.5 mg/L of GO. The study also revealed that the addition of 7.5 mg/L GO in combination with 8 μM TDZ to the MS medium facilitated the induction of multiple shoots. Moreover, the clonal fidelity of the in vitro plants treated with GO showed a genetic similarity of over 97%. These results confirm that lower GO concentrations improve plant development and stability. Consequently, this nanomaterial has a positive effect on the growth of strawberry plants and is therefore well suited for strawberry tissue culture.

Experimental and theoretical investigation of mechanical and rheological properties of compatibilized XNBR/NR/GO nanocomposites

In this research, nanocomposites based on carboxylated nitrile rubber (XNBR)/natural rubber (NR) with different concentrations of graphene oxide (GO) were prepared by melt mixing method. The role of XNBR-grafted maleic anhydride (XNBR-g-GMA) as a compatibilizer and the effect of GO content on the morphological, mechanical, rheological, and vulcanization properties were evaluated. It was observed that with increasing the concentration of GO, the scorch and vulcanization time decreased, while the torque of the samples increased. Morphological studies illustrated that by raising the concentration of GO in the presence of a compatibilizer, the fracture surface of nanocomposites became rougher and the average size of dispersed phase decreased. In addition, the presence of XNBR-g-GMA compatibilizer improved the uniform dispersion of GO within the XNBR/XNBR-g-GMA/NR matrix. The mechanical properties of nanocomposites showed the best results for XNBR/NR with a ratio of 75/25. Theoretical studies on the mechanical and rheological properties of nanocomposites performed by Mori-Tanaka and Carreau-Yasuda models and illustrated a good agreement with experimental data.

Understanding the role of graphene oxide in affecting PAHs biodegradation by microorganisms: An integrated analysis using 16SrRNA, metatranscriptomic, and metabolomic approaches

Graphene oxide (GO)-promoted microbial degradation technology is considered an important strategy to eliminate polycyclic aromatic hydrocarbons (PAHs) in the environment; however, the mechanism by which GO affects microbial degradation of PAHs has not been fully studied. Thus, this study aimed to analyze the effect of GO-microbial interaction on PAHs degradation at the microbial community structure, community gene expression, and metabolic levels using multi-omics combined technology. We treated PAHs-contaminated soil samples with different concentrations of GO and analyzed the soil samples for microbial diversity after 14 and 28 days. After a short exposure, GO reduced the diversity of soil microbial community but increased potential degrading microbial abundance, promoting PAHs biodegradation. This promotion effect was further influenced by the GO concentration. In a short period of time, GO upregulated the expression of genes involved in microbial movement (flagellar assembly), bacterial chemotaxis, two-component system, and phosphotransferase system in the soil microbial community and increased the probability of microbial contact with PAHs. Biosynthesis of amino acids and carbon metabolism of microorganisms were accelerated, thereby increasing the degradation of PAHs. With the extension of time, the degradation of PAHs stagnated, which may be due to the weakened stimulation of GO on microorganisms. The results showed that screening specific degrading microorganisms, increasing the contact area between microorganisms and PAHs, and prolonging the stimulation of GO on microorganisms were important means to improve the biodegradation efficiency of PAHs in soil. This study elucidates how GO affects microbial PAHs degradation and provides important insights for the application of GO-assisted microbial degradation technology.

SnS-rGO heterojunction: Fabrication, characterization, and visible light-induced optoelectronic performance analysis

In this article, the orthorhombic phase of pristine SnS and SnS-rGO nanostructures with different concentrations of graphene oxide was synthesized by the co-precipitation method. The cracking of FESEM images in SnS-25rGO nanostructures shows the substitution of sulfur with the oxygen of the functional groups of graphene oxide. Also, the effect of the concentration of graphene oxide was investigated on the optoelectronic efficiency of fabricated devices. The optoelectronic characterization shows that by adding graphene oxide and increasing its concentration, the semi-circle radius in the EIS analysis and the amount of photocurrent decreased and increased, respectively. These results indicate the fast transport and transfer of electrons to the substrates and the effective separation of electron-hole pairs. Finally, the calculations showed that by increasing the concentration of graphene oxide in the SnS-rGO nanostructures, the visible-light-induced optoelectronic parameters of photosensitivity, photoresponsivity, specific detectivity, and external quantum efficiency of these nanostructures significantly improved. These parameters were obtained for the SnS-25rGO nanostructure as 204, 59.88 mA/cm2, 5.98 × 1010 jones, and 166.85, respectively, each of which increased several times compared to the optoelectronic parameters of the pristine SnS. Therefore, this multiplicity increase makes these SnS-rGO nanostructures suitable for photodetector applications.

Histomorphometric evaluation of 3D printed graphene oxide-enriched poly(ε-caprolactone) scaffolds for bone regeneration

ObjectiveRestoring large boney defects using bone grafts alone is an unpredictable procedure. Biodegradable polymeric scaffolds suffer rapid biodegradation and lack sufficient osteo-conductivity. The aim of this study was to histomorphometrically evaluate three-dimensional printed graphene oxide-enriched poly(ε-caprolactone) (PCL) scaffolds for bone regeneration in a rabbit defect model using two different concentrations of graphene oxide. Basic characteristic properties and mount of new bone regeneration formation were evaluated. Methodstwo concentrations of graphene oxide (1 and 3 wt%) were added to PCL scaffolds using hot blind technique while pure PCL scaffolds served as a control. Laboratory characterization included scanning electron microscopy (SEM), x-ray diffraction analysis (XRD), contact angle, internal porosity, in addition to density measurements. All scaffolds were subjected to biodegradation evaluation and cell cytotoxicity test. In vivo bone regeneration was evaluated in the tibia defect of a rabbit model by measuring the amount of new bone formation (n = 15, ά = 0.05). ResultsSEM images showed slight reduction in pore size and increase in filament width of scaffolds with increasing GO contents. However, the printed scaffolds matched well with the dimensions of the original design. XRD patterns revealed characteristic peaks identifying microstructure of scaffolds. Addition of GO increased crystallinity of the scaffolds. The contact angle and porosity readings indicated reduction in measurements with increased content of GO indicating improved wetting properties while the density followed an opposing pattern. Higher biodegradability values were associated with higher GO content resulting in acceleration of observed biodegradation. The results of cytotoxicity test showed reduction in cell viability with higher GO content. Bone regeneration was significantly enhanced for 1 wt% GO scaffolds compared to other groups as was evident by higher bone density observed in x-ray images and higher amount of new bone formation observed at different time intervals. SignificanceGraphene oxide improved the physical and biological properties of PCL scaffolds and significantly enhanced new bone regeneration.

Synthesis of Graphene Oxide/ Poly(Vinyl Alcohol) Composite and Investigation of Graphene Oxide Effect on Diameter and Pore Size of Poly(Vinyl Alcohol) Nanofibers

The ultrafine fibers of Poly Vinyl Alcohol (PVA) /Graphene Oxide (GO) composite were prepared by using a homemade electrospinning set-up at 12.5 kV and 12 cm with different concentrations of GO (1g/L, 0.75g/L, and 0.5g/L) in PVA. The effect of GO concentrations in 10% PVA solution on the diameter of fibers was investigated. Fourier Transform Infrared (FTIR) Spectroscopy was used to analyze the functional groups. Ultraviolet (UV)-visible spectra of GO suspension showed the absorption peak at 232 nm. The morphology of the nanofibers was analyzed by Scanning Electron Microscopy (SEM). The X-ray diffraction (XRD) technique was used to analyze the crystalline nature of this material. The diameter of nanofibers decreased with improved crystallinity, thus, increasing the concentration of GO in PVA.

Enriched Graphene Oxide-Polypropylene Suture Threads Buttons Modulate the Inflammatory Pathway Induced by Escherichia coli Lipopolysaccharide.

Graphene oxide (GO), derived from graphene, has remarkable chemical-physical properties such as stability, strength, and thermal or electric conductivity and additionally shows antibacterial and anti-inflammatory properties. The present study aimed to evaluate the anti-inflammatory effects of polypropylene suture threads buttons (PPSTBs), enriched with two different concentrations of GO, in the modulation of the inflammatory pathway TLR4/MyD 88/NFκB p65/NLRP3 induced by the Escherichia coli (E. coli) lipopolysaccharide (LPS-E). The gene and the protein expression of inflammatory markers were evaluated in an in vitro model of primary human gingival fibroblasts (hGFs) by real-time PCR, western blotting, and immunofluorescence analysis. Both GO concentrations used in the polypropylene suture threads buttons-GO constructs (PPSTBs-GO) decreased the expression of inflammatory markers in hGFs treated with LPS-E. The hGFs morphology and adhesion on the PPSTBs-GO constructs were also visualized by inverted light microscopy, scanning electron microscopy (SEM), and real-time PCR. Together, these results suggest that enriched PPSTBs-GO modulates the inflammatory process through TLR4/MyD 88/NFκB p65/NLRP3 pathway.

Double-Reinforced Fish Gelatin Composite Scaffolds for Osteochondral Substitutes

Genipin crosslinked composite blends of fish gelatin/kappa-carrageenan (fG/κC) with different concentrations of graphene oxide (GO) for osteochondral substitutes were prepared by a simple solution-blending method. The resulting structures were examined by micro-computer tomography, swelling studies, enzymatic degradations, compressions tests, MTT, LDH, and LIVE/DEAD assays. The derived findings revealed that genipin crosslinked fG/κC blends reinforced with GO have a homogenous morphology with ideal pore dimensions of 200-500 µm for bones alternative. GO additivation with a concentration above 1.25% increased the blends' fluid absorption. The full degradation of the blends occurs in 10 days and the gel fraction stability increases with GO concentration. The blend compression modules decrease at first until fG/κC GO3, which has the least elastic behavior, then by raising the GO concentration the blends start to regain elasticity. The MC3T3-E1 cell viability reveals less viable cells with the increase of GO concentration. The LDH together with the LIVE/DEAD assays reports a high concentration of live and healthy cells in all types of composite blends and very few dead cells at the higher GO content.

Bactericidal Action and Industrial Dye Degradation of Graphene Oxide and Polyacrylic Acid-Doped SnO2 Quantum Dots: In Silico Molecular Docking Study.

The present work demonstrates the systematic incorporation of different concentrations of graphene oxide (GO) into a fixed amount of polyacrylic acid (PAA)-doped SnO2 quantum dots (QDs) through a co-precipitation approach. The research aimed to evaluate the catalytic and antibacterial actions of GO/PAA-SnO2 QDs. Moreover, optical properties, surface morphologies, crystal structures, elemental compositions, and d-spacings of prepared QDs were examined. X-ray diffraction patterns revealed the tetragonal configuration of SnO2, and the crystallinity of QDs was suppressed upon dopants verified by the SAED patterns. Electronic spectra identified the blue shift by incorporating GO and PAA led to a reduction in band gap energy. Fourier transform infrared spectra showed the existence of rotational and vibrational modes associated with the functional groups during the synthesis process. A drastic increase in the catalytic efficacy of QDs was observed in the neutral medium by including dopants, indicating that GO/PAA-SnO2 is a promising catalyst. GO/PAA-SnO2 showed strong bactericidal efficacy against Escherichia coli (E. coli) at higher GO concentrations. Molecular docking studies predicted the given nanocomposites, i.e., SnO2, PAA-SnO2, and GO/PAA-SnO2, as potential inhibitors of beta-lactamaseE.coli and DNA gyraseE.coli.

GO nanosheets decorated with SnS nanoparticles: excellent photocatalytic performance under visible-light irradiation.

In this study, pristine SnS and SnS/reduced graphene oxide nanostructures were synthesized using a simple and cheap co-precipitation method. To investigate the effect of graphene oxide concentration on the structural and optical properties and photocatalytic activity, SnS/graphene oxide nanocomposites were prepared with different concentrations of graphene oxide (5, 15, and 25 wt%). The synthesized nanostructures were analyzed using X-ray diffraction, FESEM, Raman spectroscopy, UV-Vis spectroscopy, photoluminescence techniques, and electrochemical impedance spectroscopy. The results of the XRD analysis confirmed the orthorhombic phase of tin sulfide for all nanostructures. The absence of a peak at 2θ = 10.21° for SnS/graphene oxide nanocomposites indicated that during the synthesis process, graphene oxide turns into reduced graphene oxide. The FESEM analysis results showed that surface cracking occurs for SnS/graphene oxide nanocomposites compared to pure graphene oxide sheets. This cracking of reduced graphene oxide sheets can act as sites for the growth of SnS nuclei on rGO. However, the presence of such nucleus sites for the growth of nanoparticles is an important factor in improving the photocatalytic efficiency of nanocomposites. The results of the Raman analysis of the nanocomposites show the highest reduction of oxygen for the SnS/rGO nanocomposite with 15 wt% concentration of graphene oxide, and this improves the conductivity and increases the separation of charge carriers. These results are confirmed by electrochemical impedance analysis with the longest lifetime (430 ns) and photoluminescence analysis with the least recombination of charge carriers for this nanocomposite. Therefore, the results of the research on the photocatalytic activity of the synthesized nanostructures for the decomposition of methylene blue under visible light irradiation show that the SnS/rGO nanocomposite has a higher efficiency than pristine SnS, and the optimal concentration of graphene oxide in the nanocomposites synthesized for 150 minutes to obtain the highest photocatalytic efficiency (more than 90%) was 15 wt%.

Enhanced The Properties of ZnO Thin Film by Graphene Oxide for Dye Sensitized Solar Cell Applications

In this present work, the effects of coating of graphene oxide (GO) at different concentrations (0, 0.2, 0.3, 0.4, 0.5, and 0.6 mg/ml) onto zinc oxide (ZnO) nanostructured were investigated. ZnO and ZnO coated with GO (ZnO/GO) were prepared using immersion method. The structural, morphology and optical properties of all samples have been studied using x-ray diffraction (XRD), field emission scanning microscopy (FESEM) and UV Vis spectroscopy. The peak obtained from the XRD pattern shows that all samples are in the hexagonal-wurtzite structure. The (002) peak shows the strongest intensity for all samples with the highest (002) peak obtained for the ZnO/GO sample coated at a GO concentration of 0.5 mg/ml. The diameter of ZnO/GO nanostructured samples decreased after coating with GO at concentrations of 0.2 to 0.5 mg/ml and the diameter increased again when ZnO nanostructures were coated with GO at above 0.5 mg/ml. The highest transmission spectrum was obtained for the ZnO/GO sample coated with GO at a concentration of 0.5 mg/ml. In conclusion, the effect of GO coating on ZnO nanostructured can be changed at different concentrations of GO. The optimal properties of ZnO/GO may be suitable as a photoanode in DSSC applications.

Effect of graphene oxide on the uptake, translocation and toxicity of metal mixture to Lepidium sativum L. plants: Mitigation of metal phytotoxicity due to nanosorption

Due to its unique structure and exceptional properties, graphene oxide (GO) is increasingly used in various fields of industry and therefore is inevitably released into the environment, where it interacts with different contaminants. However, the information relating to the ability of GO to affect the toxicity of contaminants is still limited. Therefore, the aim of our study was to synthesize GO, to examine the phytotoxicity of different concentrations of GO and its co-exposure with the metal mixture using garden cress (Lepidium sativum L.) as a test organism and to evaluate the potential of GO to affect toxicity of metals and their uptake by plants. The metal mixture (MIX) containing Ni (II), Zn (II), Cr (III) and Cu (II) was prepared in accordance with the maximum-permissible-concentrations (MPC) accepted for the inland waters in the EU. Additionally, the capacity of GO to adsorb metals was studied in specific conditions of the phytotoxicity test and assessed using adsorption isotherms. Our data indicate that in most cases the tested concentrations of MIX, GO and MIX + GO did not affect seed germination, root growth and biomass of roots and seedlings, however, they were found to alter photosynthesis processes, enhance production of carotenoids and H2O2 as well as to activate lipid peroxidation. Additionally, our study revealed that GO affects the accumulation of tested metals in roots and shoots of the MIX-exposed L. sativum. This is due to the capacity of GO to adsorb metals from the growth medium. Therefore, low concentrations of GO can be used for water decontamination.

Chitosan/Xanthan membrane containing hydroxyapatite/Graphene oxide nanocomposite for guided bone regeneration

ObjectiveTo develop a chitosan-xanthan (CX) membrane associated with Hydroxyapatite (HA) and different concentrations of graphene oxide (GO). MethodologyThe CX complex was associated with the hydroxyapatite-graphene oxide (HAGO) nanocomposite in different concentrations. The experimental groups were:1) CX; 2) Chitosan-Xanthan/Hydroxyapatite (CXHA); 3) Chitosan-Xanthan/Hydroxyapatite-Graphene Oxide 0.5% (CXHAGO 0.5%); 4) CXHAGO 1.0%; 5) CXHAGO 1.5%. The membranes characterizations were performed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Contact angle, Tensile Strength, in vitro Bioactivity and the in vitro Cell viability (MTT test). The data was submitted to the Normality and Homogeneity tests. In vitro Indirect Cytotoxicity assay data was statistically analyzed by two-way ANOVA and Tukey's test (α = 0.05). Tensile Strength and Contact Angle data were statistically analyzed by one-way ANOVA followed by Tukey's test (α = 0.05). ResultsXRD, FTIR and Raman spectroscopy confirmed the characteristic bands of the CX polymeric complex, the phosphate bands related to HA, and the presence of GO. SEM images demonstrated the non-porous and homogeneous surface of membranes. The contact angle test showed the hydrophilic characteristic of all membranes (p > 0.05). CX showed tensile strength significantly higher than other membranes. The apatite deposition was observed in all membranes after performing the bioactivity test. The cell viability of CXHAGO 1.0% and CXHAGO 1.5% was significantly higher than CX. ConclusionThe addition of HAGO reduced the mechanical strength of membranes, but improved its cell viability. It demonstrated the potential of CXHAGO membranes to be used in guided bone regeneration therapies.