Graphene Oxide Fe3O4 Research Articles

Determination of capsaicinoids by magnetic solid phase extraction coupled with UPLC-MS/MS for screening of gutter oil

Capsaicinoids, including capsaicin, dihydrocapsaicin and N-vanillylnonanamide have been identified as characteristic markers for gutter oil. In this study, the nanocomposite of graphene oxide–Fe3O4 (GO–Fe3O4) was synthesized by a co-precipitation method, and applied to magnetic solid phase extraction (MSPE) process. The capsaicin, dihydrocapsaicin and N-vanillylnonanamide extracted in gutter oil were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Under the optimized pretreatment conditions, the limit of detection (LOD) and limit of quantification (LOQ) are 0.15 and 0.4 µg L−1, respectively. The linear range is 0.4–200 µg L−1, and the correlation coefficients (R2) are over 0.996 for all three compounds. The recoveries range from 81.2% to 103.3% for soybean oil and 71.2% to 84.3% for rapeseed oil. The values of matrix effect range in 87.6%–105.5% and 83.4%–110.6% and the intra-day RSDs range from 2.8%–4.6% to 4.8%–6.1% for soybean oil and rapeseed oil, respectively. The adsorbent can be reused for multiple times with no appreciable loss of adsorption capability. The present methodology has high potential for screening of gutter oil in food samples, thus having importance for food safety monitoring.

Perceptive removal of toxic azo dyes from water using magnetic Fe3O4 reinforced graphene oxide–carboxymethyl cellulose recyclable composite: Adsorption investigation of parametric studies and their mechanisms

A magnetic FGC composite was prepared using Fe3O4 particles and graphene oxide–carboxymethyl cellulose which were blended as the source materials. The adsorptive interactions of FGC matrix with dye molecules like Congo Red (CR), Acid Red 1 (AR1) and Reactive Red 2 (RR2) were examined and explained through various analytical techniques. The optimum conditions for the adsorption of dyes include the initial concentration of dyes (50 mg/L), volume of dyes (50 mL), adsorbent dosage (100 mg) and solution pH (3-6). In these conditions, the FGC showed extreme adsorption efficiency of 45.09, 47.32 and 46.21 mg/g for the removal of CR, AR1 and RR2 dye molecules, respectively. The Freundlich isotherm data shows better fit for dye molecules adsorption. The thermodynamic results confirmed the endothermic and spontaneous nature in adsorption. The mechanism of CR, AR1 and RR2 dyes adsorption on FGC composite follows the interactions such as electrostatic attraction, hydrogen bonding, π−π stacking, and surface complexation. The FGC composite was regenerated over 65% after five consecutive cycles using an aqueous 0.1 M NaOH solution. The FGC composite showed an enhanced adsorption capacity for the removal of toxic azo dyes. Hence, the prepared composite could be used as a potential adsorbent for the removal of dye molecules from contaminated water.

Removal performance and mechanism of Fe3O4/graphene oxide as an efficient and recyclable adsorbent toward aqueous Hg(II)

Decontamination of aqueous heavy metal is a challenging task of environmental remediation. Herein, we demonstrated an adsorptive method for efficient removal of aqueous Hg(II) using a magnetic nanocomposite Fe3O4/graphene oxide (Fe3O4/GO). Adsorption of Hg(II) onto Fe3O4/GO equilibrated in 4 min, with the adsorption percent and quantity of 91.17% and 547.01 mg g−1, respectively. Fe3O4/GO can be easily recovered from solution via magnetic separation for reuse, and retaining 73.5% of its original capacity after five consecutive cycles. The Temkin model and PSO model were most suitable for describing adsorption in equilibrium and non-equilibrium state, respectively. Both GO and Fe3O4 adsorbed Hg(II) via donating electrons in oxygen atoms toward Hg(II). Moreover, GO made a major contribution, while Fe3O4 made a minor one to adsorption. The facile preparation, high adsorption efficiency, easy recovery, and reusability may enable Fe3O4/GO to be a promising adsorbent for aqueous Hg(II).

Two-dimensional superlattice-like sheets of superparamagnetic graphene oxide/magnetic nanoparticle hybrids

Using a simple and facile method, we precisely controlled the two-dimensional layered array structure of graphene oxide (GO)–iron oxide (Fe3O4) nanoparticle hybrid multilayer films and investigated the correlation between the assembled structure of the hybrid films and their magnetic properties. GO–Fe3O4 nanoparticle hybrids were obtained via the ligand exchange of oleic acid-functionalized Fe3O4 nanoparticles with GO at the gas–liquid interface. Hybrids of oriented Fe3O4 nanoparticles and GO monolayers spontaneously formed at the gas–liquid interface, which were subsequently deposited on solid substrates using the Langmuir–Schaefer (LS) technique. Two-dimensional superlattices of GO–Fe3O4 nanoparticle hybrids were fabricated through repeated LS deposition of the nanoparticle monolayer with a hexagonal array structure sandwiched between GO monolayers. The magnetic properties of the GO–Fe3O4 multilayer were measured using SQUID magnetometry. From the field cooling/zero field cooling results, we found that the 2D superlattice-like layered structure of the GO–Fe3O4 multilayer facilitates the layer-dependent properties in the out-of-plane field case due to the dipolar interactions between the top and bottom layers.

One-pot synthesis of spirooxindole-pyrrolizidine compounds using magnetically separable Fe3O4-graphene oxide (Fe3O4-GO) catalyst

A couple of novel Spirooxindole-pyrrolizidine compounds have been synthesized from chalcone derivatives as α, β-unsaturated carbonyl compounds by the help of heterogeneous magnetically separable Fe3O4-GO catalyst. Four steps involved in this research are synthesis of Fe3O4-GO catalyst, synthesis of chalcone derivatives from 4-hydroxybenzaldehyde and cinnamaldehyde, synthesis of spirooxindole-pyrrolizidine derivatives by 1,3-dipolar-cycloaddition reaction through the formation of azomethine ylide, and the last is antioxidant activity assay using DPPH method. The result showed that the use of Fe3O4-GO catalyst as much as 5 wt% can increase the reaction yield to 86.27 %. From the DPPH assay, it is known that spirooxindole-pyrrolizidine derivatives have an antioxidant activity but spirooxindole-pyrrolizidine derived from 4-hydroxybenzaldehyde is the better one.

Optimal design of a lightweight and thin radar absorbing nanocomposite

Recently, attention to polymeric nanocomposites has gained a great extent as they present new opportunities to provide superior properties in microwave absorbing materials. In this study polystyrene (PS) nanocomposites containing various nano-fillers were successfully synthesized and employed as microwave absorbing materials. The mentioned materials are usually designed to solve protection against electromagnetic interference in wireless communication systems and high frequency circuit mechanisms. In this study the performance of three various polystyrene (PS) nanocomposites containing: semi-conductor zinc oxide, non-metallic conductive graphene oxide and magnetic Fe3O4 were compared. The fillers type was selected as variable parameter and its influence on the electromagnetic wave absorption and reflection loss (RL) amount was investigated. The scanning electron microscopy (SEM) was used in morphological and particle size study of the nanocomposites. The electromagnetic wave absorption properties of nanocomposites were studied and compared using a vector network analyzer (frequency range of 5-8 GHz). The results indicate that at the same preparation conditions the polystyrene/graphene oxide nanocomposites have higher absorption compared with others.

Laccase Immobilized Fe3O4-Graphene Oxide Nanobiocatalyst Improves Stability and Immobilization Efficiency in the Green Preparation of Sulfa Drugs

This paper, reports on the novel and green synthesis procedure for sulfonamides that involved the immobilization of Trametes Versicolor laccase onto the Fe3O4–graphene nanocomposite via glutaraldehyde (GA) crosslinking (Lac/Fe3O4/GO). Various parameters, mainly, activation time, GA, and laccase concentration were investigated and optimized. The results showed that the optimal contact time was 4 h, GA concentration was 5% while laccase concentration was 5 mg·mL−1, at which a high enzyme activity recovery was achieved (86%). In terms of the stability of immobilized laccase to temperature and storage conditions, the performance of the nanobiocatalyst was found to significantly exceed that of free laccase. The results have indicated that nearly 70% of relative activity for immobilized laccase remained after the incubation period of 2 h at 55 °C, but only 48% of free laccase remained within the same time period. Moreover, the immobilized laccase retained 88% of its initial activity after storage for 20 days. In case of the free laccase, the activity retained within the same time period was 32%. In addition, the nanobiocatalyst possessed better recycling performance as evidenced from the observation that after eight cycles of repeated use, it retained 85% of its original activity.

Multi-field-coupling energy conversion for flexible manipulation of graphene-based soft robots

Soft robots enabling controllable movement in a predicable manner have attracted enormous research interests. However, current researches on soft robots are mainly limited to single actuation mode, and thus complex and multidimensional motility is significantly limited. Here, we propose and demonstrate for the first time a multi-field-coupling energy conversion strategy for flexible manipulation of soft robots, by which 3D-positioning, rotating, levitating, capturing and releasing of a small object by a smart claw are synergistically realized via magnetic, ultrasonic, humidity and light fields. The essence of the strategy is coupling design of the robot compositional materials that can convert energy from different fields into efficient mechanical works. As a typical example, we developed a magnetic-field-assisted gradient assembly method for preparing asymmetric Fe3O4 nanoparticles (NPs) and graphene oxide (GO) composite film. The asymmetric distribution of Fe3O4 NPs in GO leads to an reasonable mechanical stiffness and alters the water adsorption capability of the two sides, which not only imparts multi-responsiveness but also suitably addresses the problem of interlayer detachment in the case of bimorph actuators. The robust soft robots demonstrate good durability, revealing great potential for developing advanced robotic systems that permit direct conversion of multi-field energies to mechanical works.

Magnetic Fe3O4-graphene oxide nanocomposite – synthesis and practical application for the heterogeneous photo-Fenton degradation of different dyes in water

ABSTRACT Characterization and test a magnetic graphene oxide (GO) nanocomposite (Fe3O4-GO) in the photo-degradation of Methylene Blue (MB), Reactive Black 5 (RB), and Acid Blue 80 (AB) dyes were investigated in this work. Measurements indicated that GO was decorated by Fe3O4. Kinetic tests showed that the process was more efficient in degrade MB – %Degradation MB>RB>AB; also in the regeneration and reuse of the photocatalyst. Regarding the phytotoxicity, all seeds germinated, although a decrease in the root length after the photodegradation was observed. In overall, Fe3O4-GO seems to be a promissory photocatalyst for the degradation of different textile dyes.

Synthesis of rGO/p-Fe3O4@PANI three-phase nanomaterials and electromagnetic wave absorption properties

A novel rGO/p-Fe3O4@PANI three-phase nanomaterial was prepared by coating conductive polyaniline (PANI) on reduced graphene oxide (rGO) and porous Fe3O4 (p-Fe3O4), which can increase the reflection interface of electromagnetic waves and extend the reflection path of electromagnetic waves propagating inside the material, and between them. Three kinds of rGO/p-Fe3O4@PANI samples were prepared. The mass percentage of PANI in the samples was established. The mass ratio of rGO to p-Fe3O4 was changed to ameliorate the impedance matching and attenuation constant. Compared with rGO/p-Fe3O4, rGO/p-Fe3O4@PANI exhibits excellent electromagnetic wave absorption performance. When the mass ratio of rGO to p-Fe3O4 in the 40 wt% three-phase material is 1:5 and the thickness is 2.5 mm, the minimum RL of rGO/p-Fe3O4@PANI is −41.38 dB at 9.75 GHz and the effective absorption bandwidth to electromagnetic wave reaches 3.08 GHz (from 8.40 to 11.48 GHz), indicating that is a potentially attractive candidate for high efficiency electromagnetic wave absorbers. The combination of the conductive polymer, porous magnetic nanoparticles and rGO improves the impedance matching condition to some extent, and effectively increases the attenuation constant of the material.

Magnetic Properties of Poly(trimethylene terephthalate‐block‐Poly(tetramethylene oxide) Copolymer Nanocomposites Reinforced by Graphene Oxide–Fe3O4 Hybrid Nanoparticles

Thermoplastic elastomeric nanocomposites based on poly(trimethylene terephthalate‐block‐poly(tetramethylene oxide) copolymer (PTT‐PTMO) and graphene oxide (GO)–Fe3O4 nanoparticles hybrid are prepared by in situ polymerization. Superparamagnetic GO–Fe3O4 hybrid nanoparticles before introducing to elastomeric matrix are characterized by X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effect of loading (0.3 and 0.5 wt%) of GO–Fe3O4 nanoparticle hybrid on the phase structure, tensile, and magnetic properties of synthesized nanocomposites is investigated. The phase structure of nanocomposites is evaluated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Dispersion of GO–Fe3O4 nanoparticles in elastomeric matrix is evaluated by transmission electron microscopy (TEM). Magnetic properties of GO–Fe3O4 nanoparticle hybrid and nanocomposites with their content are characterized using two different techniques: direct current superconducting quantum interference device (dc SQUID) magnetization measurements as a function of temperature (from 2 to 300 K) and external magnetic field and ferromagnetic resonance (FMR) at microwave frequency.

Electrochemical Determination of Levodopa on Carbon Paste Electrode Modified with Salmon Sperm DNA and Reduced Graphene Oxide–Fe3O4 Nanocomposite

In this work, an electrochemical label-free DNA biosensor was developed for determination of levodopa (LD). The biosensor was constructed using reduced graphene oxide decorated with Fe3O4 magnetic nanoparticles (rGO–Fe3O4) on a carbon paste electrode (CPE) and double-stranded deoxyribonucleic acid (DNA) (DNA/rGO–Fe3O4-CPE). The application was related to the molecular interaction between LD and DNA. Thus, the voltammetric behavior of LD at the surface of DNA/rGO–Fe3O4-CPE was studied using differential pulse voltammetry (DPV) where the oxidation peak current of LD was measured as an analytical signal. A considerable increase was observed in the oxidation signal of LD at the DNA-coated electrode compared to the DNA-free electrode, indicating the pre-concentration of LD due to the interaction with the surface-confined DNA layer. Scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy confirmed the structure of the synthesized nanocomposites (electrode composition). Electrochemical studies revealed that modification of the electrode significantly increases the oxidation peak currents of LD. Under the optimum conditions, the calibration curve was linear in the range of 0.5–600 nM with a detection limit of 0.11 nM. The relative standard deviation for 200.0 nM was 4.07% (n = 5). The developed biosensor was successfully applied to the analysis of LD in human serum and urine sample.

An enzymatic performance for a new swift magnetically detachable bio-conjugate of Candida rugosa lipase with modified Fe3O4–graphene oxide nanocomposite

The high stability, reusability, half-life, and catalytic activity, accompanied by facile separation from the reaction products, are essential for fulfilling the promise of biocatalysts for different applications in analytical and industrial processes. Here, the Candida rugosa lipase (CRL) immobilization on a new chemically modified, magnetically coated graphene oxide nanosheets is presented. The synthesis, modification, and CRL immobilization operations are monitored and verified through XRD, VSM, FT-IR, TEM, SEM, EDS, UV−Vis, and AFM techniques. The appraisal of operational parameters reveals the high-grade reusability, high pH, thermal, and storage stability of the synthesized swift magnetically detachable biocatalyst. The molecular interpretation of this catalytic performance represents by enzyme–enzyme and enzyme–product interactions. This unique magnetic bio-conjugate with outstanding performance recommends for analytical and industrial applications in a wide range of temperature and pH.

A beta-cyclodextrin-functionalized magnetic metal organic framework for efficient extraction and determination of prochloraz and triazole fungicides in vegetables samples

A β-cyclodextrin-functionalized magnetic zinc-metal organic framework (M-MOF/β-CD) was synthesized via a facile one-pot reaction. M-MOF/β-CD was used as a magnetic porous absorbent for the extraction and determination of prochloraz and three triazole fungicides in vegetable samples. M-MOF/β-CD was prepared by creating MOF layers on the surface of a Fe3O4–graphene oxide (GO) nanocomposite and bonding them with β-CD molecules. Characterization suggested that a 3D porous structure was formed, with M-MOF/β-CD exhibiting high superparamagnetism and a large surface area. As a new strategy, integrating MOFs with Fe3O4–GO could improve their water-resistance and mechanical strength by providing a rigid nanosupport interface. Combining M-MOF and β-CD resulted in excellent selective adsorption capacities for prochloraz and three triazole fungicides. The static adsorption process was evaluated and the results were in good agreement with the Freundlich model. Subsequently, M-MOF/β-CD was applied to extracting prochloraz and triazole fungicides from tomato and lettuce vegetables, followed by HPLC-MS/MS determination. The limits of detection for the above fungicides were found to be 0.25–1.0 μg/L at a signal-to-noise ratio of 3, with spiked recoveries of 74.13%–119.83%, indicating that M-MOF/β-CD was promising for application to the extraction and determination of fungicides in complex matrices.

Graphene oxide-Fe3O4 nanocomposite magnetic solid phase extraction followed by UHPLC-MS/MS for highly sensitive determination of eight psychoactive drugs in urine samples

Graphene oxide–Fe3O4 (GO–Fe3O4) nanocomposite was synthesized by a facile chemical co-precipitation method. The GO–Fe3O4 was used as magnetic sorbent to extract the eight psychoactive drugs from urine samples. The analytes are morphine (MOR), 6-monoacetylmorphine (6-MAM), amphetamine (AMP), methamphetamine (MAMP), codeine, cocaine, dolantin and benzoylecgonine (BZE), which were determined by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method has high selectivity for the target analytes. The limit of detection (LOD) and limit of quantification (LOQ) were 0.02–0.2 μg L−1 and 0.05–0.5 μg L−1, respectively. The Mandel's fitting test revealed good linearity within all linear ranges. The linear ranges were calculated as 0.05–1000 μg L−1 for AMP, MAMP, cocaine and dolantin; 0.1–1000 μg L−1 for 6-MAM and codein; and 0.5–1000 μg L−1 for MOR and BZE. The recoveries ranged in 80.4–105.5%. The intra-day and inter-day RSDs are in the range of 2.7–13.1% and 3.9–13.7%, respectively. Magnetic solid phase extraction (MSPE) with GO–Fe3O4 provides a convenient, rapid and green sample pretreatment method for extracting the target psychoactive drugs from urine. This methodology can be used for simultaneous or individual detection of eight major psychoactive drugs with high sensitivity. This method has high potential in clinical and forensic areas for psychoactive drugs analysis.

Synthesis of Graphene Oxide-Fe3O4 Based Nanocomposites Using the Mechanochemical Method and in Vitro Magnetic Hyperthermia.

The study presented in this work consists of two parts: The first part is the synthesis of Graphene oxide-Fe3O4 nanocomposites by a mechanochemical method which, is a mechanical process that is likely to yield extremely heterogeneous particles. The second part includes a study on the efficacy of these Graphene oxide-Fe3O4 nanocomposites to kill cancerous cells. Iron powder, ball milled along with graphene oxide in a toluene medium, underwent a controlled oxidation process. Different phases of GO-Fe3O4 nanocomposites were obtained based on the composition used for milling. As synthesized nanocomposites were characterized by x-ray diffraction (XRD), alternating magnetic field (AFM), Raman spectroscopy, and a vibrating sample magnetometer (VSM). Additionally, the magnetic properties required to obtain high SAR values (Specific Absorption Rate-Power absorbed per unit mass of the magnetic nanocomposite in the presence of an applied magnetic field) for the composite were optimized by varying the milling time. Nanocomposites milled for different extents of time have shown differential behavior for magneto thermic heating. The magnetic composites synthesized by the ball milled method were able to retain the functional groups of graphene oxide. The efficacy of the magnetic nanocomposites for killing of cancerous cells is studied in vitro using HeLa cells in the presence of an AC (Alternating Current) magnetic field. The morphology of the HeLa cells subjected to 10 min of AC magnetic field changed considerably, indicating the death of the cells.

Attenuation of electromagnetic microwaves by a sandwich-like hybrid nanocomposite of reduced graphene oxide and amine-functionalized magnetic mesoporous silica

Abstract A hybrid composite with a sandwich-like structure constructed from reduced graphene oxide (rGO) and magnetic Fe3O4 particles coated mesoporous SiO2 (Fe3O4@mSiO2) is reported. For better adhesion of Fe3O4@mSiO2 on the rGO sheets, the surface of the Fe3O4@mSiO2 was modified with amonopropyltriethoxysilane to form amine-functionalized magnetic mesoporous silica (AMS). The anchoring of AMS particles on the surface of rGO in the resulting reduced graphene oxide/amine-functionalized magnetic mesoporous silica (rGAMS) hybrid greatly improved exfoliation of the rGO sheets. The as-synthesized rGAMS readily absorbed microwave radiation in epoxy composites. An rGAMS absorber with 10 wt% filler loading had an effective absorption bandwidth of 9.8 GHz in the frequency from 8.2 to 18 GHz, and the minimum reflection loss was -49.4 dB at 13.4 GHz. The adhesion of AMS particles not only induced a high specific surface area, but also acted as loci for microwave entrapment due to magnetic loss caused by their intrinsic porosity.

Reduced Graphene Oxide-Fe3O4 Nanocomposite Based Nanofluids: Study on Ultrasonic Assisted Synthesis, Thermal Conductivity, Rheology, and Convective Heat Transfer

The present work deals with the preparation of reduced graphene oxide-Fe3O4 (rGO-Fe3O4) nanocomposite and its nanofluid by an ultrasound assisted method for convective heat transfer study. Formatio...

Preparation of PMMA/GO and PMMA/GO-Fe3O4 nanocomposites for malachite green dye adsorption: Kinetic and thermodynamic studies

The adsorption performances of as prepared poly(methyl methacrylate)/graphene oxide-Fe3O4 (PMMA/GO-Fe3O4) and poly (methyl methacrylate)/graphene oxide (PMMA/GO) nanocomposite as adsorbents were investigated for malachite green (MG) dye removal. For MG dye adsorption on PMMA/GO and PMMA/GO-Fe3O4 nanocomposite, 35 min was selected as the best contact time because there was no main change after 35 min. Optimum adsorption of the dye by both adsorbents occurred at 298 K. The calculated values of the entropy (ΔS°), enthalpy (ΔH°) and Gibbs energy (ΔG°) indicated that the adsorption process was exothermic in nature. The results indicated that PMMA/GO and PMMA/GO-Fe3O4 were good adsorbents for removing MG dye from aqueous solution and were good construed with the pseudo-second-order type (I) due to the law value for chi-square (X2) and high value of the correlation coefficients.

Multifunctional Photo- and Magnetoresponsive Graphene Oxide-Fe3O4 Nanocomposite-Alginate Hydrogel Platform for Ice Recrystallization Inhibition.

Tuning ice recrystallization (IR) has attracted tremendous interest in fundamental research and a variety of practical applications, including food and pharmaceutical engineering, fabrication of anti-icing coating and porous materials, and cryopreservation of biological cells and tissues. Although great efforts have been devoted to modulation of IR for better microstructure control of various materials, it still remains a challenge, especially in cryopreservation, where insufficient suppression of IR during warming is fatal to the cells. Herein, we report an all-in-one platform, combining the external physical fields and the functional materials for both active and passive suppression of IR, where the photo- and magnetothermal dual-modal heating of GO-Fe3O4 nanocomposites (NCs) can be used to suppress IR with both enhanced global warming and microscale thermal disturbance. Moreover, the materials alginate hydrogels and GO-Fe3O4 NCs can act as IR inhibitors for further suppression of the IR effect. As a typical application, we show that this GO-Fe3O4 nanocomposite-alginate hydrogel platform can successfully enable low-cryoprotectant, high-quality vitrification of stem cell-laden hydrogels. We believe that the versatile ice recrystallization inhibition platform will have a profound influence on cryopreservation and tremendously facilitate stem cell-based medicine to meet its ever-increasing demand in clinical settings.