Magnetic Core Shell Nanocomposites Research Articles

Co-immobilization of crosslinked enzyme aggregates on lysozyme functionalized magnetic nanoparticles for enhancing stability and activity

Surface chemistry of carriers plays a key role in enzyme loading capacity, structure rigidity, and thus catalyze activity of immobilized enzymes. In this work, the two model enzymes of horseradish peroxidase (HRP) and glucose oxidase (GOx) are co-immobilized on the lysozyme functionalized magnetic core-shell nanocomposites (LYZ@MCSNCs) to enhance their stability and activity. Briefly, the HRP and GOx aggregates are firstly formed under the crosslinker of trimesic acid, in which the loading amount and the rigidity of the enzyme can be further increased. Additionally, LYZ easily forms a robust anti-biofouling nanofilm on the surface of SiO2@Fe3O4 magnetic nanoparticles with abundant functional groups, which facilitate chemical crosslinking of HRP and GOx aggregates with minimized inactivation. The immobilized enzyme of HRP-GOx@LYZ@MCSNCs exhibited excellent recovery activity (95.6 %) higher than that of the free enzyme (HRP&GOx). Specifically, 85 % of relative activity was retained after seven cycles, while 73.5 % of initial activity was also remained after storage for 33 days at 4 °C. The thermal stability and pH adaptability of HRP-GOx@LYZ@MCSNCs were better than those of free enzyme of HRP&GOx. This study provides a mild and ecofriendly strategy for multienzyme co-immobilization based on LYZ functionalized magnetic nanoparticles using HRP and GOx as model enzymes.

Highly selective removal of thorium from acidic solutions achieved on phosphonic acid functionalized core–shell magnetic nanocomposite: Understanding adsorption and binding mechanisms

Thorium has received widespread attention as potential nuclear fuel alternative for the next-generation thorium-based molten salt reactors. With the growth of nuclear energy, it is needful to exploit magnetic nanomaterials to remove thorium from aqueous solutions, owing to their superparamagnetism and large specific surface energy. Nevertheless, most of magnetic nanomaterials often suffered from low thorium selectivity and poor structural ability in acidic solutions. Herein, a novel core–shell magnetic nanocomposite Fe3O4@SiO2/P (AA-MMA-VPA) possessing phosphonic acid was developed by a controlled radical polymerization of vinylphosphonic acid (VPA) in the presence of Fe3O4 encapsulated by SiO2 (Fe3O4@SiO2). Due to the presence of the high content of phosphonic acid groups and the absence of any universal groups, Fe3O4@SiO2/P (AA-MMA-VPA) displayed exceptional selectivity for thorium in the presence of 11 co-existing cations. The separation factor STh/M value for Fe3O4@SiO2/P(AA-MMA-VPA) concerning all other competing cations surpassed 74.4, and the largest value for STh/M even amounted to 343.5. Further, Fe3O4@SiO2/P (AA-MMA-VPA) possessed a maximum adsorption capacity (qmax) of 485.4 mg g−1 at pH of 3.0, higher than that of other magnetic sorbents. By reason of its core–shell structure, the sorbent possessed an outstanding structure stability even after immersed into HNO3 solution at pH of 0.5 for 72 h. The sorbent could as well be magnetically recouped, and recycled at least six times without evident diminution in sorption amount. The sterling removal performance of the sorbent was assigned to the interaction of thorium with phosphonic acid, corroborated by FT-IR, XPS and DFT method. Thus, this study affords a new viewpoint for exploiting magnetic nanomaterials with sterling acidic resistance for the strongly selective entrapment of thorium from acidic media.

Core-shell magnetic nanocomposite Fe3O4@SiO2@CS@POCl2-x for alcohols to alkyl halides transformation

In this study, we examined the efficiency of a new magnetic core-shell nanocomposite, Fe3O4@SiO2@CS@POCl2-x (NCP@ POCl2-x), which carries POCl2-x functional groups (where X can be 0, 1, or 2) on its surface. The nanocomposite was explored as a reagent for converting alcohols into alkyl halides using molecular bromine (Br2) or iodine (I2) as a model organic transformation. The conversion process demonstrated promising practical applications with ease of operation, and the pure product could be conveniently isolated through magnetic filtration, simplifying the synthesis process. The surface characteristics of the nanocomposite were thoroughly investigated using vibrating-sample magnetometer (VSM) spectrum analysis, field emission scanning electron microscopy (FESEM) images, and Fourier-transform infrared spectroscopy (FT-IR). TEM imaging also confirmed the core-shell structure of the nanocomposite, and XRD analysis revealed distinct peaks corresponding to the presence of Fe3O4. The study demonstrates that NCP@ POCl2-x is an effective reagent for alkyl halide transformations, offering various possibilities for applications in organic synthesis.

Cu(II) supported on Chitosan/LDH/Fe3O4 magnetic nanocomposite as an effective heterogeneous nanocatalyst for synthesizing bis(indolyl) methanes under ultrasonic conditions

Chitosan is a natural, nontoxic biopolymer with amine and hydroxyl functional groups which make it easy for chitosan molecules to form intermolecular and intramolecular hydrogen bonds. In that context, the present study reports Cu(II) supported on Chitosan@MgCuAl-LDH@Fe3O4 magnetic nanocomposite (Fe3O4@MgCuAl-LDH@CS/Cu(II)) as an effective and a novel heterogeneous catalyst to perform electrophilic substitution reaction between indoles and aromatic aldehydes to yield bis(indolyl)methane derivatives (BIMs) in shorter reaction time under ultrasonic conditions. Copper ions were mainly adsorbed onto the core–shell magnetic nanocomposite (Fe3O4@MgCuAl-LDH) modified with chitosan by the chelating capacity of chitosan and LDH. The catalyst's physicochemical properties and morphological structure were characterized using advanced analytical techniques, including XRD, FT-IR, FESEM, HRTEM, TGA, VSM, ICP-OES and EDX. Overall, the results show that Sonication significantly enhanced the catalytic performances compared to conventional heating. Also, the prepared catalyst could be easily separated from the solution using an external magnetic field and reused up to nine times without considerable leaching or loss in its catalytic activity.

High-performance NiO@Fe3O4 magnetic core-shell nanocomposite for catalytic ozonation degradation of pharmaceutical pollution.

Pharmaceuticals that are present in superficial waters and wastewater are becoming an ecological concern. Therefore, it is necessary to provide high-performance methods to limit the harmful ecological effects of these materials to achieve a sustainable environment. In this research, NiO@Fe3O4 nanocomposite was prepared by the co-precipitation method and utilized in the catalytic ozonation process for the degradation of 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-quinoline-3-carboxylic acid (ciprofloxacin antibiotic), for the first time. The influencing parameters in the degradation process were analyzed and optimized via response surface methodology (RSM). The optimal ciprofloxacin removal efficiency (100%) was found at pH = 6.5, using 7.5 mg of the NiO@Fe3O4 nanocatalyst and 0.2 g L-1 h-1 ozone (O3) flow, applied over 20 min. Results showed a significant synergistic effect in the analyzed system, which makes the proposed catalytic ozonation process more efficient than using the catalyst and ozone separately. Also, based on the kinetic analysis data, the catalytic ozonation process followed the pseudo-first-order model. In addition, the nanocatalyst showed high recyclability and stability (88.37%) after five consecutive catalytic ozonation process cycles. In conclusion, the NiO@Fe3O4 nanocatalyst/O3 system can be effectively used for the treatment of pharmaceutical contaminants.

Solid state – Green construction of starch- beaded Fe3O4@Ag nanocomposite as superior redox catalyst

In this present work, a novel approach which had been developed for the green synthesis of starch-decorated Fe3O4 @Ag nanocomposite by using one-step grinding method. The magnetic core shell nanocomposite was designed by magnetite (Fe3O4) surrounded by the starch (maize corn), a biopolymer which act as a matrix for argentum (Ag) nanoparticles. This leads to the core shell structure starch – Fe3O4 @Ag nanocomposite (NC). The morphological and physical properties of the prepared nanocomposite was characterized by FE-SEM, HR-TEM, XPS, VSM, XRD, FT-IR and UV-Vis spectroscopic studies. The average particle size of the nanocomposite was found to be 9–11 nm. In addition, the nanocomposite gains a retentivity magnetisation of 25.50 emu/g makes the NC saveable for reusability. The nanocomposite had a greater stability for more than a month was confirmed with the help of UV-DRS and XRD analysis. The main advantage of the catalyst is temperature independent; During the conversion of benzaldehyde to benzoic acid, the product yield was achieved higher at ambient condition. Furthermore, the NC exposes the outstanding catalytic performance for reductive degradation of various carcinogenic water pollutants such as Methylene Blue (MB) and Methyl Red (MR) within 14 min and 18 min respectively. Moreover, it is also capable for reduction of 4-nitrophenol in an efficient manner. Thus, the NC holds a greater activity towards oxidation and reductive degradation reaction.

Highly crosslinking core-shell magnetic nanocomposites based catalyst and heat free polymerization for isolation of glycoprotein.

New approaches for the engineering of well-defined, pore modality, and multi-chemical functionality nanocomposites are crucial to generate the next generation of functional materials with recoverable and easy preparation properties. Here, a catalyst and heat free polymerization reaction is exploited and fabricated zwitterionic system around magnetic nanoparticles. N-aminoethyl piperazine propane sulfonate (AEPPS) and dopamine (DA) are introduced as the zwitterionic system, which provided abundant zwitterionic groups (NH2, SO3-, N+) and strong adhesion and various oxidation state properties. And that, the zwitterionic engineering will assemble between AEPPS and DA whereby Schiff base formation or Michael type addition. Whereafter, a series of sophisticated array of microscopic, spectroscopic, and structure techniques verify the formation of highly crosslinking internal zwitterionic architectures, well-defined core-shell structure, and better porosity. The zwitterionic structure-function relationships and striking porous structure are explored in a multi-interaction adsorption assay. The adsorption capacity of the magnetic nanocomposites was 1065.8mg/g. And that, the system exhibited with hydrophilic-hydrophobic activity towards glycoprotein and better performance to bioactive protein (Ig-G) isolation form human whole blood sample. The synergistic enhancement interaction in hydrophilic target enrichment, easy preparation, and soft substrate properties of the AEPPS-DA zwitterionic materials make them intriguing candidates for sustainable biomedical loading and chromatographic separation.

Metal decorated silica-based core-shell magnetic nanocomposite for the solid-phase microextraction of cadmium(II) with determination by high-resolution continuum source flame atomic absorption spectrometry

The present study describes a facile and environmentally friendly hydrothermal method for the fabrication of metal decorated silica-based core-shell magnetic nanocomposite M@Si-MNCs, applied as a sustainable coating material for the solid-phase microextraction of toxic cadmium ions. M@Si-MNCs were characterized by scanning electron microscopy, X-ray-diffraction, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller analyzer. Relevant parameters have been studied to obtain maximum recovery, including pH, adsorbent dosage, model solution volume, - adsorption and desorption time, and matrix effects. The developed method obtained excellent linearity from 50 to 500 µg/L with a limit of detection of 1.2 µg/L and a limit of quantification of 4.1 µg/L. The new method was applied for separation, preconcentration and determination of cadmium in environmental and tobacco samples.

Sonochemical Preparation of a Magnet-Responsive Fe3O4@ZIF-8 Adsorbent for Efficient Cu2+ Removal.

This work presents a novel approach to synthesizing magnetic core-shell nanocomposites, consisting of magnetic nanoparticles and a metal-organic framework, for environmental applications. The synthesis is based on the encapsulation of magnetic Fe3O4 nanoparticles with microporous zeolitic imidazolate framework-8 (ZIF-8) nanocrystals via ultrasonic activation under a continuous supply of precursor solutions. This sonochemical approach is proven to be a fast, cost-effective, and controllable route for the preparation of magnet-responsive Fe3O4@ZIF-8 nanoparticles with a core-shell structure. The functional nanomaterial possesses a high content of ZIF-8 and combined micro/mesoporosity, and thus can be used as adsorbents that can be easily separated using a magnet. In particular, the sonochemically prepared Fe3O4@ZIF-8 exhibits significant adsorption performance for the removal of copper ions from water: a short adsorption time (10 min), high maximum uptake capacity (345 mg g−1), and excellent removal efficiency (95.3%). These performances are interpreted and discussed based on the materials characteristics of Fe3O4@ZIF-8 established by microscopy, gas sorption, X-ray diffraction, and thermal analysis.

Rapid Microwave-Assisted Synthesis of Fe3O4/SiO2/TiO2 Core-2-Layer-Shell Nanocomposite for Photocatalytic Degradation of Ciprofloxacin

In this work, magnetic nanoparticles based on magnetite were successfully prepared via rapid microwave-assisted synthesis. In order to obtain the ternary core–shell Fe3O4/SiO2/TiO2 nanocomposite, first magnetite (Fe3O4) nanoparticles were coated with a protective layer of silica (SiO2) and finally with titania (TiO2). The composite configuration comprising porous and photoactive shells should facilitate the removal of organic micropollutants (OMPs) from water. Furthermore, the magnetic core is critical for processing the management of the photocatalytic powder suspension. The magnetization of the prepared magnetic nanoparticles was confirmed by vibrating-sample magnetometry (VSM), while the structure and morphology of the core–shell nanocomposite were investigated by means of XRD, FTIR, and SEM. Adsorption and photocatalysis were evaluated by investigating the removal efficiency of ciprofloxacin (CIP) as a model OMP using the prepared magnetic core–shell nanocomposite under UV-A light irradiation. It was found that the Fe3O4/SiO2/TiO2 nanocomposite showed good synergistic adsorption and photocatalytic properties. The measurement of iron in eluate confirmed that no leaching occurred during the photocatalytic examination. The recovery of magnetic nanocomposite by an external magnetic field confirmed that the magnetically separated catalyst is highly suitable for recycling and reuse.

Core-Shell-Structured Covalent-Organic Framework as a Nanoagent for Single-Laser-Induced Phototherapy.

Imaging-guided phototherapy, including photothermal therapy and photodynamic therapy, has been emerging as a promising avenue for precision cancer treatment. However, the utilization of a single laser to induce combination phototherapy and multiple-model imaging remains a great challenge. Herein, we report, the first of its kind, a covalent-organic framework (COF)-based magnetic core-shell nanocomposite, Fe3O4@COF-DhaTph, that is used as a multifunctional nanoagent for cancer theranostics under single 660 nm NIR irradiation. Besides significant photothermal and photodynamic effects, it still permits triple-modal magnetic resonance/photoacoustic/near-infrared thermal (IR) imaging due to its unequaled magnetic and optical performance. We believe that the results obtained herein could obviously promote the application of COF-based multifunctional nanomaterials in cancer theranostics.

Synthesis and characterization of magnetic wrinkled mesoporous silica nanocomposites containing Fe3O4 or CoFe2O4 nanoparticles for potential biomedical applications

We report the preparation of magnetic wrinkled mesoporous silica (MWMS) nanocomposites by either seeding magnetic nanoparticles during the preparation of the WMS nanoparticles (Fe3O4@WMS and CoFe2O4@WMS) or by mixing via sonication of the magnetic and the wrinkled mesoporous silica (WMS) nanoparticles (WMS-Fe3O4 and WMS-CoFe2O4). The morphology and physical properties of the nanocomposites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and dynamic light scattering. Raman spectroscopy was used to detect the magnetic nanoparticles embedded into the silica matrix or anchored on the WMS surface, as a fast and convenient analytical tool for the identification of metal oxide phases present in the magnetic nanocomposites. Depending on the preparation method, magnetic nanoparticles were located at the center of the WMS particles, producing well-defined core-shell magnetic nanocomposites or they were present anchored on the surface of the fibrous structure of the mesoporous silica nanoparticles. The resulting MWMS nanocomposites may become potentially useful in biomedical applications as drug delivery systems or contrast agents for magnetic resonance imaging.

Oxygen-independent free radical generation mediated by core-shell magnetic nanocomposites synergizes with immune checkpoint blockade for effective primary and metastatic tumor treatment

Advanced or metastatic tumor treatment is a long-lasting problem that leads to high mortality. Photodynamic therapy (PDT) has emerged as a promising clinical therapeutic strategy with the ability of destroying local tumors and initiating systemic anti-tumor immune responses for metastasis inhibition. However, the efficacy is typically limited by tumor hypoxia, aggregation caused self-quenching of classic photosensitizers (PSs), and intrinsic or adaptive immune resistance that mediated by cellular and molecular immunosuppressive components. Here, we designed an oxygen-independent photosensitizer by core-shell magnetic nanocomposites (MNCs), with functionalized iron oxide nanoclusters as the core and coordination polymerization of Zinc Tetra (N-methyl-4-pyridyl) porphyrin (ZnTMPyP) as the shell. MNCs PDT induced persistent free radical generation via facilitating an effective electron-hole separation, polarized macrophages to pro-inflammatory M1 phenotype, and activated systemic antitumor immunity. Nevertheless, adaptive immune resistance occurred simultaneously, characterized by highly increased PD-L1 expression on tumor cells, dendritic cells (DCs) and macrophages. As a result, combined use of MNCs PDT with checkpoint blockade effectively suppressed well-established primary tumors as well as tumor metastasis via a ‘trident’ modality, including persistent free radical generation in both normoxic and hypoxic conditions for direct tumor destruction, enhanced frequency of tumor infiltrating-lymphocytes (TILs) and modified tumor immunosuppressive microenvironment with reduced immunosuppressive cells and PD-L1 blockade. We also explore the underlying mechanisms of metastasis inhibition according to the transcriptome expression profiling of lung tissues, which revealed that the ‘trident’ modality altered numerous genes mainly related to immuno-activation and cancer associated signaling pathways. We expect the expanded use of this platform for various types of cancer malignancy.

Ag NPs on chitosan-alginate coated magnetite for synthesis of indazolo[2,1-b]phthalazines and human lung protective effects against α-Guttiferin

Biocomposite nanomaterials have been evolved as the new generation catalysts and therapeutic supplement in these days. Magnetically isolation has added new features to this category. This has encouraged us to synthesize a novel Ag NP adorned chitosan-alginate dual bio-polysaccharide (two of the more versatile polysaccharides) modified core-shell magnetic nanocomposite (Fe3O4/CS-Alg/Ag NPs). The material was meticulously characterized following different physicochemical techniques, such as, FT-IR, ICP-OES, FESEM, EDX, atomic mapping, TEM, VSM, XRD and XPS studies. The as synthesized material was catalytically explored in the one-pot multicomponent synthesis of biologically potent 2H-indazolo[2,1-b]phthalazine-trione derivatives involving a wide range of substrates. The reactions were ended up with excellent yields under solvent-free heating conditions. The catalyst recyclability, heterogeneity and leaching tests were performed to ensure its high stability and robustness. It could be reused as much as 10 times in succession with almost unchanged catalytic performances. In the lung protective part of the present research, the human lung toxicity was induced by α-Guttiferin. The cell viability of lung MRC-5, CCD19Lu, WI-38, and BEAS-2B cell lines was measured by trypan blue assay. Caspase-3 activity was assessed by the caspase activity colorimetric assay kit and mitochondrial membrane potential of lung cells was studied by Rhodamine123 fluorescence dye. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test was used to show DNA fragmentation and apoptosis of lung cells. Also, the Rat inflammatory cytokine assay kit was used to measure the concentrations of inflammatory cytokines. The catalyst-treated cell cutlers significantly (p ≤ 0.01) reduced the DNA fragmentation, caspase-3 activity, and inflammatory cytokines concentrations, and raised the mitochondrial membrane potential and cell viability in the high concentration of α-Guttiferin-treated lung MRC-5, CCD19Lu, WI-38, and BEAS-2B cells. The best result of lung protective properties of catalyst against α-Guttiferin was seen in the high dose of catalyst i.e., 4 μg. DPPH test revealed similar antioxidant potentials for catalyst and butylated hydroxytoluene. The catalyst inhibited half of the DPPH molecules in the concentration of 171 μg/mL. According to the above results, catalyst can be administrated as a lung protective drug for the treatment of lung diseases after approving in the clinical trial studies in humans.

Hydrogen generation by catalytic hydrolysis of sodium borohydride using the nano-bimetallic catalysts supported on the core-shell magnetic nanocomposite of activated carbon

The purpose of this study were to prepare the novel supported bimetallic cobalt-nickel catalysts on the core-shell magnetic nanocomposite of activated carbon derived from wood by sequential and co-deposition-precipitation. The performance of the prepared catalyst was evaluated for the hydrogen generation from hydrolysis of sodium borohydride. The magnetic catalysts were characterized by applying the XRD, XPS, FTIR, FESEM, TEM, ICP, BET and VSM tests. The hydrogen generation rate was increased with the reduction of calcination temperature. The well dispersed magnetic nanoparticles were fabricated with average size below of 30 nm which was confirmed by TEM, FESEM and XRD results. The activity of the prepared samples with respect to the preparation method was illustrated to follow a specific order: Co/Ni/MWAC > Ni/Co/MWAC > Co–Ni/MWAC. The developed model derived from design of experiments could correlate the operating parameters with the experimental data while the correlation coefficient was achieved to be 0.99. The hydrogen generation rate was increased with increasing the reaction temperature and the concentration of sodium borohydride in the alkaline solutions. The hydrogen generation rate was measured to be 740.70 ml min−1. gcat−1 in the presence of the Co/Ni/MWAC at 30 °C. The experimental study also indicated that the hydrolysis of sodium borohydride was a zero order type reaction and the activation energy was calculated 40.70 kJ mol−1. The stability of the prepared sample was also investigated for six cycles which showed the acceptable performance of the synthesized catalyst for the practical applications.

Fe3O4@PDA@MnO2 core-shell nanocomposites for sensitive electrochemical detection of trace Pb(II) in water

In this study, Fe3O4@PDA@MnO2 core-shell magnetic nanocomposites were synthesized for the first time, and used to enrich target analyte to construct an electrochemical sensor for sensitive detection of trace Pb(II) in the environmental samples. A dense polydopamine (PDA) coating was firstly formed on the surface of Fe3O4 to ensure high stability because the developed method is employed under strongly acidic conditions. Then a high adsorption capacity MnO2 shell can be simply introduced to the surface of the PDA as a result of the redox activity between PDA and KMnO4. Differential pulse voltammetry (DPV) was applied for determining target metal ions. Chemical and electrochemical factors, including quantity of Fe3O4@PDA@MnO2 nanocomposites, preconcentration solutions pH, preconcentration time and supporting electrolytes, were optimized. Under excellent conditions, the designed sensor demonstrated a linear response to Pb(II) within the range of 0.1–150 μg L−1 and with a detection limit of 0.03 μg L−1. The proposed methodology exhibited excellent performance in selectivity, sensitivity and long-term stability, and was also successfully applied to determine Pb(II) in the real water samples. This study suggested that Fe3O4@PDA@MnO2 nanocomposites are a better alternative to Pb(II) analysis resulting from its low cost, low toxicity, strong adsorption, and good reproducibility.

Detection of 3,4-diaminotoluene based on Sr0.3Pb0.7TiO3/CoFe2O4 core/shell nanocomposite via an electrochemical approach

We reported a scalable sol–gel method for the preparation of Sr0.3Pb0.7TiO3/CoFe2O4 core–shell magnetic nanocomposite with a finely controlled shell and evaluated its efficiency as an electrochemical sensor for the selective detection of 3,4-diaminotoluene.

CoFe2O4–Fe3O4 bimagnetic heterostructure: a versatile core-shell nanoparticle with magnetically recoverable photocatalytic and self heating properties

CoFe2O4–Fe3O4 (Fe/Co = 2.3, 2.75 & 3.5) core-shell magnetic nanocomposite (MNC) was successfully prepared by combined sonochemical and reverse co-precipitation method using cost effective and readily available precursor. The structure, morphology, thermal, optical and magnetic properties of the MNC was extensively studied and the product was found suitable for use as an environmentally safe recyclable photocatalyst for pollution control. The self-heating properties of the MNC was also investigated for magnetic hyperthermia application. The studies of Infrared (IR) and Ultraviolet-visible (UV-Vis) spectroscopy confirmed the synthesis and formation of the bimagnetic heterostructure. The x-ray Diffraction studies and Transmission Electron Microscopy (TEM) analysis confirmed the formation of subnanometer clusters (<10 nm) in the asprepared samples. The results of Differential Scanning Calorimetry (DSC)/Thermo-Gravimetric Analysis (TGA) analysis of the as prepared samples showed transformation of intermediate Fe-phases to Fe3O4 during sample heating at 420 °C. This transformation accompanied structural changes in the asprepared sample that led to the formation of the coreshell structure which was observed in the TEM images of the annealed sample with Fe/Co ratio (x = 3.5). The magnetization-hysteresis (M-H) studies was done on the asprepared and annealed samples using the Vibrating Sample Magnetometer (VSM). The VSM studies showed significant improvement of magnetization and coercivity in the annealed samples making it suitable for re-usability in photocatalytic reaction and magnetic hyperthermia application. The degradation of phenolphthalein (a non-biodegradable organic chemical) in the presence of UV light irradiation was used as a reference reaction to confirm the photocatalytic properties of the CoFe2O4–Fe3O4 MNC, which could be well isolated from the media at the end of degradation, by applying an external magnetic field and reused. The nanocomposite was also investigated for magnetic hyperthermia using induction heating properties and the result infer that it is also a promising material for hyperthermia application.

Preparation and characterization of novel polyoxometalate/CoFe2O4/metal-organic framework magnetic core-shell nanocomposites for the rapid removal of organic dyes from water.

In this study, the MIL-101(Cr) metal–organic framework was functionalized with a Dowson-type polyoxometalate (P2W18O626−; POM) and magnetic spinel cobalt ferrite (CoFe2O4; CFO) through a hydrothermal route and was characterized by means of FT-IR, XRD, FE-SEM, EDX, BET, and VSM measurements. All analyses confirmed the successful encapsulation of POM (∼32.2 wt%) into the magnetic MIL-101(Cr) framework. Compared to the pristine MIL-101(Cr) MOF, the as-prepared magnetic ternary nanocomposite (abbreviated as POM/CFO/MIL-101(Cr)) demonstrated a notable decrease in both the surface area and pore volume because of the incorporation of CoFe2O4 nanoparticles and huge P2W18O626− polyanions into the cages of the MIL-101(Cr) framework. The POM/CFO/MIL-101(Cr) was then applied as a magnetically separable adsorbent for the rapid elimination of rhodamine B (RhB), methyl orange (MO), and methylene blue (MB) dye pollutants from aqueous solutions. For achieving the optimized conditions, the effects of initial pH, initial dye concentration, temperature, salt effect, and adsorbent dose on MB and RhB elimination were investigated. The dye adsorption isotherms followed the Langmuir model and pseudo-second-order kinetic model. The POM/CFO/MIL-101(Cr) composite material not only exhibited a fast adsorption rate towards dye molecules, but also demonstrated the selective adsorption of the cationic dyes in wastewater. The recycling experiments also demonstrated that the POM/CFO/MIL-101(Cr) adsorbent was highly stable and could be quickly recovered under a magnetic field without any alteration in the structure. The high adsorption capacity, simple fabrication method, rapid separation by a magnet and supreme reusability of the POM/CFO/MIL-101(Cr) nanocomposite make it an attractive adsorbent for the elimination of cationic dyes from wastewater.

A Carbon Paste Electrode Modified by Graphene Oxide/Fe3O4@SiO2/Ionic Liquid Nanocomposite for Voltammetric Determination of Acetaminophen in the Presence of Tyrosine

Herein, we introduce a novel modification process for carbon paste electrode by magnetic core–shell nanocomposite of graphene oxide/Fe3O4@SiO2 and n-hexyl-3-methylimidazolium hexafluoro phosphate as ionic liquid. Electrochemical features of this modified carbon paste electrode and its performance evaluation in simultaneous detection of acetaminophen and tyrosine via voltammetric oxidation was investigated. Moreover, diagnostic techniques including cyclic voltammetry, square wave voltammetry and chronoamperometry were applied in order to study the electrochemical oxidation behavior of this sensor toward acetaminophen. According to square wave voltammetry results, linear dynamic range between 1.0 × 10–6–1.0 × 10–3 M was observed for acetaminophen. The function of modified electrode in real samples containing acetaminophen and tyrosine was satisfactory.