Nanoparticle-decorated Reduced Graphene Oxide Research Articles

Green Fabrication of Co3O4 Nanoparticle-Decorated Reduced Graphene Oxide Sheets: Evaluation of Biocompatibility on Human Mesenchymal Stem Cells for Biomedical Applications

Two-dimensional monolayer structures of graphene-based materials and their hybrids offer interesting physico-chemical properties and have been extensively explored in a wide variety of applications in recent years. We have developed a simple, rapid, eco-friendly and cost-effective route for the synthesis of cobalt oxide (Co3O4) nanoparticle-decorated reduced graphene oxide (GO) by using date syrup as the reducing agent. The GO reduction process occurs simultaneously with Co3O4 nanoparticle formation at 95 °C under stirring. The structure and composition of the Co3O4 nanoparticle-decorated reduced graphene oxide (rGO) sheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Our XRD and SEM results suggested that the Co3O4 nanoparticles decorated the surface of the rGO. The biocompatibility of the Co3O4 nanoparticle-decorated rGO (Co3O4-rGO) was assessed using human mesenchymal stem cells (hMSCs) as in vitro model by MTT cell viability assay and AO/EB staining. The cell viability assay indicated that Co3O4-rGO exhibited biocompatibility with hMSCs. Compared with a control, no changes were observed in the fluorescent microscopy images of cells exposed to Co3O4-rGO. Our present findings suggest a green and easy route for the synthesis of biocompatible Co3O4-rGO with hMSCs, which is promising for biomedical applications.

Ni nanoparticle-decorated reduced graphene oxide for non-enzymatic glucose sensing: An experimental and modeling study

In this study, we used a facile approach to decorate Ni nanoparticles (Ni-NPs) with ethylene glycol followed by their adsorption on reduced graphene oxide (rGO) nanosheets for the development of enzyme free electrochemical glucose sensor. The effect of Ni-NP content (0.14, 0.28, 0.42, and 0.56wt.%) on electrochemical properties and the molecular interaction of glucose with Ni-NPs/rGO in glucose sensing were evaluated. Ni-NPs/rGO showed significantly higher electrochemical performance for the glucose oxidation in alkaline solution compared to rGO. Specifically, 0.42% Ni-NPs/rGO revealed excellent performance for glucose determination with a wide linear range (0.25μM to 1200μM), a highly reproducible response and long-term stability with the calculated detection limit of 0.01μM. Moreover, the reliability of the Ni-NPs/rGO sensor was confirmed by evaluating glucose concentration in human blood serum. Ab initio calculations were employed to reveal molecular interactions of glucose with Ni-NPs/rGO. The results showed Ni13 cluster with icosahedral geometry facing the graphene sheet is the most stable structure. Furthermore, the glucose molecule was able to adsorb on the graphene sheet through Ni13 nanoclusters and the adsorption process is closely dependent on the orientation of Ni13 nanoclusters.

A novel solid-state electrochemiluminescence sensor for detection of cytochrome c based on ceria nanoparticles decoratedwith reduced graphene oxide nanocomposite.

A novel ultrasensitive sensing system for the rapid detection of cytochrome c (CytC) was developed on the basis of an electrochemiluminescence (ECL) method. A nanocomposite biosensor was made of reduced graphene oxide decorated with cerium oxide/tris(2,2-bipyridyl)ruthenium(II)/chitosan (CeO2NPs-RGO/ Ru(bpy)3 (2+)/CHIT) and used for this purpose. The ECL signal was produced by an electrochemical interaction between Ru(bpy)3 (2+) and tripropyl amine (TPA) on the surface of the electrode. Addition of CytC to the solution decreases the ECL signal due to its affinity for TPA and inhibition of its reaction with Ru(bpy)3 (2+). The effects of the amount of CeO2NPs-RGO, Ru(bpy)3 (2+), TPA concentration as a co-reactant, and the pH of the electrolyte solution on the ECL signal intensity were studied and optimized. The results showed that the method was fast, reproducible, sensitive, and stable for the detection of CytC. The method has a linear range from 2.5nM to 2μM (R (2) = 0.995) with a detection limit of 0.7nM. Finally, the proposed biosensor was used for the determination of CytC in human serum samples with RSDs of 1.8-3.6%. The results demonstrate that this solid-state ECL quenching biosensor has high sensitivity, selectivity, and good stability. Graphical Abstract A novel solid-state electrochemiluminescence sensor for detection of cytochrome C based on Ceria Nanoparticles Decorated Reduced Graphene Oxide Nanocomposite.

Na-ion Storage Performances of FeSe(x) and Fe2O3 Hollow Nanoparticles-Decorated Reduced Graphene Oxide Balls prepared by Nanoscale Kirkendall Diffusion Process.

Uniquely structured FeSex-reduced graphene oxide (rGO) composite powders, in which hollow FeSex nanoparticles are uniformly distributed throughout the rGO matrix, were prepared by spray pyrolysis applying the nanoscale Kirkendall diffusion process. Iron oxide-rGO composite powders were transformed into FeSex-rGO composite powders by a two-step post-treatment process. Metallic Fe nanocrystals formed during the first-step post-treatment process were transformed into hollow FeSex nanoparticles during the selenization process. The FeSex-rGO composite powders had mixed crystal structures of FeSe and FeSe2 phases. A rGO content of 33% was estimated from the TG analysis of the FeSex-rGO composite powders. The FeSex-rGO composite powders had superior sodium-ion storage properties compared to those of the Fe2O3-rGO composite powders with similar morphological characteristics. The discharge capacities of the FeSex- and Fe2O3-rGO composite powders for the 200th cycle at a constant current density of 0.3 A g−1 were 434 and 174 mA h g−1, respectively. The FeSex-rGO composite powders had a high discharge capacity of 311 mA h g−1 for the 1000th cycle at a high current density of 1 A g−1.

One-pot synthesis of MnFe2O4 nanoparticles-decorated reduced graphene oxide for enhanced microwave absorption properties

MnFe2O4 nanoparticles are successfully decorated on the surface of the reduced graphene oxide (RGO) sheets through a simple, one-step hydrothermal method. The morphology, microstructure and electromagnetic properties of MnFe2O4/RGO composite were characterized by XRD, TEM, XPS, VSM and vector network analyser. The maximum reflection loss (RL) of MnFe2O4/RGO composite is −32.8 dB at 8.2 GHz with the thickness of 3.5 mm, and the absorption bandwidth with the RL below −10 dB is up to 4.8 GHz (from 7.2 to 12 GHz). The results demonstrate that the introduction of RGO significantly enhances microwave absorption performance of the MnFe2O4. It is believed that such composite can be a powerful candidate in the field of microwave absorption.

Fabrication of dog-bone shaped Au NRcore–Pt/Pdshell trimetallic nanoparticle-decorated reduced graphene oxide nanosheets for excellent electrocatalysis

Dog-bone shaped Au NRcore–Pt/Pdshell decorated reduced graphene oxide nanocomposites (GMTs) exhibit outstanding electrocatalytic activity and durability towards ethanol oxidation reaction.

The hydrogen sensing properties of Pt–Pd/reduced graphene oxide based sensor under different operating conditions

Uniform nanocrystalline Pt–Pd nanoparticle-decorated reduced graphene oxide has been synthesized and applied to hydrogen sensing.

Fabrication of gold nanoparticles-decorated reduced graphene oxide as a high performance electrochemical sensing platform for the detection of toxicant Sudan I

In this paper, we are presenting a facile, green and in situ synthesis strategy for the convenient preparation of well-dispersed gold nanoparticles (AuNPs)-decorated reduced graphene oxide (RGO) without the use of any template molecules and poisonous reductant. The as-synthesized nanocomposite has been detailedly characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis as well as electrochemical technologies. The morphological and structural characterizations illustrate that AuNPs can be efficiently decorated on RGO with the Au content of 20.33wt% in the matrix and the size of the embedded AuNPs vary between 25 and 40nm. The electrochemical investigations confirm that the small-sized AuNPs on the RGO film can remarkably boost the electrocatalytic activity for the oxidation of Sudan I, which can be used as an enhanced electrochemical sensing platform for the sensitively detection of the toxicant Sudan I. Moreover, the kinetic parameter studies demonstrate that the Sudan I electro-oxidation at the AuNPs/RGO electrode is a diffusion-controlled process which involves two-electron and two-proton transfer. Under the optimal conditions, a wide linear range of Sudan I detection from 0.01 to 70μmolL−1 with good linearity (R2=0.9965, 0.9942) and a low detection limit (1.0nmolL−1, S/N=3) were obtained. In comparison with the existing analogues ever reported, the AuNPs/RGO eletrode exhibits overwhelmingly superior comprehensive properties for the sensitive detection of Sudan I. Finally, the newly developed sensor was applied to quantitative determination of Sudan I in food samples such as chilli powder and ketchup sauce with satisfactory sensitivity, selectivity and reversibility.

Au@Pd core–shell nanoparticles-decorated reduced graphene oxide: a highly sensitive and selective platform for electrochemical detection of hydrazine

An Aucore–Pdshell-decorated reduced graphene oxide nanocomposite is successfully employed for the electrochemical detection of low-level hydrazine in an aqueous solution.

Simultaneous and sensitive determination of melatonin and dopamine with Fe3O4nanoparticle-decorated reduced graphene oxide modified electrode

An electrochemical sensor based on a new nanocomposite of graphene/Fe3O4has been fabricated for simultaneous determination of melatonin and dopamine.

Surface Enhanced Raman Scattering by Gold Nanoparticle-Decorated Reduced Graphene Oxide on ITO-Coated Glass

Surface Enhanced Raman Scattering by Gold Nanoparticle-Decorated Reduced Graphene Oxide on ITO-Coated Glass

Green synthesis of nanostructed Ni-reduced graphene oxide hybrids and their application for catalytic reduction of 4-nitrophenol

Abstract We developed an environmentally friendly, one-pot strategy toward preparation of Ni nanoparticles-decorated reduced graphene oxide (Ni-RGO) hybrids, through the use of ethylene glycol as both solvent and reducing agent under solvothermal conditions. Several analytical techniques were used to characterize the resulting Ni-RGO hybrids, which showed that the monodispersed Ni nanoparticles with average diameter of 8 nm were uniformly anchored onto RGO sheets. Furthermore, taking the advantage of the synergetic effects between supported Ni nanoparticles and RGO sheets, Ni-RGO hybrids exhibited a better catalytic activity than pure Ni NPs for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride, with kinetic reaction rate being over 2.5 times that of pure Ni NPs.

Sonochemical synthesis of CuS/reduced graphene oxide nanocomposites with enhanced absorption and photocatalytic performance

The CuS nanoparticle-decorated reduced graphene oxide (CuS/rGO) composites have been successfully prepared via a sonochemical method. X-ray diffraction and electron microscopy observations confirm that CuS nanoparticles of 10–25nm are well distributed on the rGO nanosheets. Ultraviolet–visible spectroscopy reveals the CuS/rGO nonocomposites show a strong and broad light absorption. Photocatalytic performance of the CuS/rGO nanocomposites is evaluated by measuring the decomposition of methylene blue solution under natural light. The experimental results reveal that the as-prepared nanocomposites show remarkably enhanced photocatalytic activity compared with pure CuS. This can be attributed to the enhanced light adsorption, strong dyestuff absorption, and efficient charge transport after the introduction of rGO.

Graphene–Fe3O4/PIL–PEDOT for the design of sensitive and stable quantum chemo-resistive VOC sensors

Quantum chemo-resistive vapour sensors have been synthesised from the assembly of magnetic nanoparticles-decorated reduced graphene oxide (Fe3O4–RGO) with poly(3,4-ethylene dioxythiophene) (PEDOT) and poly(ionic liquid) (PIL). This new hybrid sensing material demonstrated enhanced sensitivity, selectivity, signal-to-noise ratio and reduced response time compared to its elementary constituents (also sensitive), which suggests that a positive synergy of properties has been reached through the structuring of the conducting architecture by spray layer-by-layer. The Fe3O4-RGO/PIL–PEDOT sensor exhibited stable and reproducible signals at room temperature for both polar (ethanol, methanol, acetone, water) and non-polar (chloroform, styrene, dichlorobenzene, toluene) volatile organic compounds (VOC), considered as food degradation biomarkers. Since sensor’s responses are still well defined at the ppm level (and may be even at the subppm level) as attested by a SNR around 10, an application such smart packaging could be envisaged.

High stability silver nanoparticles–graphene/poly(ionic liquid)-based chemoresistive sensors for volatile organic compounds’ detection

Hybrids of silver nanoparticle-decorated reduced graphene oxide (Ag-RGO) have been prepared with the use of poly(ionic liquid) (PIL) as a versatile capping agent to develop volatile organic compound (VOC) sensors. The hybrid materials of Ag-RGO/PIL were assembled into three-dimensional-laminated nanostructures, where spherical Ag nanoparticles with diameters between 50 and 300 nm were homogeneously distributed on the graphene sheets and interspaced between them. Ag-RGO/PIL sensors were fabricated by spray layer-by-layer technique and used to detect a set of polar (methanol, ethanol, methyl acetate, acetone and water) and non-polar (chloroform, dichlorobenzene, toluene and styrene) organic vapours. Much higher sensitivity and discriminability were obtained for polar vapours although non-polar ones could also be detected. In comparison with either simple reduced graphene oxide or carbon nanotubes (CNT) functionalised by PIL, the hybrid Ag-RGO/PIL-based sensors showed superior performances in terms of sensitivity, selectivity, stability and high reliability. For example, a signal-to-noise ratio up to 168 was obtained for 1 ppm of methanol and signals drift between two experiments spaced out in the time of 3 months was less than 3%. It is expected that by extrapolation, a limit of detection at the parts per billion level can be reached. These results are promising to design e-noses based on high stability chemoresistive sensors for emerging applications such as anticipated diagnostic of food degradation or diseases by the analysis of VOC, some of them being in this case considered as biomarkers.

Direct electrochemistry of glucose oxidase immobilized on ZrO2nanoparticles-decorated reduced graphene oxide sheets for a glucose biosensor

Schematic representation of the preparation procedure of GOx–PLL/RGO–ZrO2composite.

One-pot synthesis of α-Fe2O3 nanoparticles-decorated reduced graphene oxide for efficient nonenzymatic H2O2 biosensor

Hematite nanoparticles (α-Fe2O3) are successfully decorated on the reduced graphene oxide (rGO) sheets through a simple, one-step, hydrothermal method without addition of other reducing agents. The α-Fe2O3/rGO hybrid was characterized by scanning electron micrographs, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. This α-Fe2O3/rGO hybrid has been successfully applied in the catalytic performance toward the reduction of H2O2. The nonenzymatic sensor demonstrates a linear relationship over a wide concentration range of 5.0–4495.0μM (R=0.9998), a low detection limit of 1.0μM, and a high sensitivity of 126.9μAcm−2mM−1 to the detection of H2O2.

One-pot green synthesis of Ag nanoparticles-decorated reduced graphene oxide for efficient nonenzymatic H2O2 biosensor

Ag nanoparticles (AgNP) with an average size of 12nm are successfully decorated on the reduced graphene oxide (rGO) sheets through a simple one-pot hydrothermal method using gallic acid as the reducing agent. This AgNP/rGO hybrid has been successfully applied in the catalytic performance toward the reduction of H2O2. The nonenzymatic sensor demonstrates a linear relationship in a wide concentration range of 0.05–5mM (R=0.999), and a high sensitivity of 255μAcm−2mM−1 to the detection of H2O2.

Simultaneous and sensitive determination of ascorbic acid, dopamine, uric acid, and tryptophan with silver nanoparticles-decorated reduced graphene oxide modified electrode

In this paper, we report the synthesis of silver nanoparticle-decorated reduced graphene oxide composite (AgNPs/rGO) by heating the mixture of graphene oxide and silver nitrate aqueous solution in the presence of sodium hydroxide. This material was characterized by means of X-ray diffraction, UV–vis spectroscopy, and transmission electron microscopy. AgNPs/rGO based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Electrochemical studies were carried out by using cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. AgNPs/rGO modified electrode exhibited excellent electrocatalytic activity, stability, sensitivity, and selectivity with well-separated oxidation peaks toward ascorbic acid, dopamine, uric acid, and tryptophan in the simultaneous determination of their quaternary mixture. The analytical performance of this material as a chemical sensor was demonstrated for the determination of ascorbic acid and dopamine in commercial pharmaceutical samples such as vitamin C tablets and dopamine injections, respectively. The applicability of this sensor was also extended in the determination of uric acid in human urine samples.

Magnetically Separable Fe3O4 Nanoparticles-Decorated Reduced Graphene Oxide Nanocomposite for Catalytic Wet Hydrogen Peroxide Oxidation

Fe3O4 nanoparticles-decorated reduced graphene oxide magnetic nanocomposites (Fe3O4/rGO NCs) were prepared by a facile one-step strategy, and further used as heterogeneous Fenton-like catalysts for catalytic wet hydrogen peroxide oxidation (CWHPO) of methylene blue (MB) at 25 °C and atmospheric pressure. The effects of variables such as the Fe3O4/rGO with the mass ratio of rGO, initial pH, MB concentration and H2O2 dosage were investigated. The Fe3O4/rGO NCs with rGO mass ratio of 10.0 wt % showed the highest H2O2-activating ability, which was six-fold than that of pure Fe3O4 nanoparticles (NPs). The resulting catalysts demonstrated high catalytic activity in a broad operation pH range from 5 to 9, and still retained 90.5 % catalytic activity after reuse in five cycles. Taking advantage of the combined benefits of rGO and magnetic Fe3O4 NPs, these Fe3O4/rGO NCs were confirmed as an efficient heterogeneous Fenton-like catalyst for CWHPO to treat organic pollutants. And a reasonable catalytic mechanism of Fe3O4/rGO NCs was proposed to interpret the degradation process.