Modification of superparamagnetic iron oxide nanoparticles with poly(diallyldimethylammonium chloride) at air atmosphere

Superparamagnetic iron oxide particles with average size less than 20 nm were prepared by chemical co‐precipitation method in the air atmosphere. After that, polydimethyldiallyl ammonium chloride (PDDA) was used for wrapping iron oxide particles to obtain the core/shell nanocomposites. The parameters influencing properties of iron oxide particles and iron oxide/PDDA nanocomposites were investigated and optimized. The prepared iron oxide and nanocomposites were characterized by X‐ray diffraction (XRD) measurement, transmission electron microscopy (TEM), particle size and Zeta potential analyzer, Fourier transform infrared (FTIR) spectroscopy, and vibrating sample magnetometry (VSM), respectively. It was found that the iron oxide particles are cubic inverse spinel Fe₃O₄ with spherical shape. Superparamagnetic behavior of Fe₃O₄ with 73.114 emu/g is produced with NH₄OH as precipitator, and decreased to 58.583 emu/g for Fe₃O₄/PDDA nanocomposites. The Zeta potential of nanocomposites is positive value. The results showed that Fe₃O₄/PDDA nanocomposites have excellent future using as a carrier for bonding with some negative charged particles. Copyright © 2016 John Wiley & Sons, Ltd.     

Superparamagnetic Fe3O4@Alginate supported L-arginine as a powerful hybrid inorganic–organic nanocatalyst for the one-pot synthesis of pyrazole derivatives

Hybrid inorganic–organic material Fe₃O₄@Alg@CPTMS@Arg, was prepared by the layer-by-layer techniques through grafting l-arginine (l-arg) to Fe₃O₄@Alg using 3-chloropropyltrimethoxysilane (CPTMS) as a linker. Fe₃O₄@Alg was prepared by in situ co-precipitation of iron (iii) and iron (ii) chloride in the presence alginate (Alg). The hybrid inorganic–organic material was characterized employing various techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The as-prepared Fe₃O₄@Alg@CPTMS@Arg nanoparticles mediated the synthesis of pyrazole derivatives with via one-pot reaction between phenylhydrazine, malononitrile, and various aromatic aldehydes under reflux in ethanol. Recycled catalyst exhibited comparable efficacy after seven cycles. The high catalytic activity, excellent yields, as well as the recyclability of the hybrid nanomaterials with quantitative efficiency, are factors that render this environmentally benign procedure appealing.     

Conducting and magnetic behaviors of monodispersed iron oxide/polypyrrole nanocomposites synthesized by in situ chemical oxidative polymerization

This study describes the preparation of nanocomposites fabricated from monodispersed iron oxide (Fe₃O₄) and polypyrrole (PPy) by in situ chemical oxidative polymerization. The monodispersed 4 nm Fe₃O₄ nanoparticles which served as cores were synthesized using the thermal decomposition of a mixture of Iron (III) acetylacetonate and oleic acid in the presence of high boiling point solvents. The resulting nanoparticles were further dispersed in an aqueous solution with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form micelle/Fe₃O₄ spherical templates that avoid the aggregation of Fe₃O₄ nanoparticles during the further preparation of the nanocomposites. The Fe₃O₄/PPy nanocomposites were then synthesized via in situ chemical oxidative polymerization on the surface of the spherical templates. Both field‐emission scanning electron microscopy (FESEM) and high‐resolution transmission electron microscopy (HRTEM) images indicate that the resulting Fe₃O₄ nanoparticles are close to spherical dots with a particle size of about 4 nm and a standard deviation of less than 5% (4 ± 0.2 nm). Structural and morphological analysis using FESEM and HRTEM showed that the fabricated Fe₃O₄/PPy nanocomposites are core (Fe₃O₄)‐shell (PPy) structures. Morphology of the nanocomposites shows a remarkable change from spherical to tube‐like structures as the content of monodispersed Fe₃O₄ nanoparticles increases from 9% up to 24 wt %. The conductivities of these Fe₃O₄/PPy nanocomposites are about six times higher than those of PPy without Fe₃O₄. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4647–4655, 2007     

Constructing magnetic Fe3O4‐Au@CeO2 hybrid nanofibers for selective catalytic degradation of organic dyes

Au nanoparticles (Au NPs) play a vital role in heterogeneous catalytic reactions. However, pristine Au NPs usually suffer from poor selectivity and difficult recyclability. In this work, Fe₃O₄‐Au@CeO₂ hybrid nanofibers were prepared via a simple one‐pot redox reaction between HAuCl₄ and Ce (NO₃)₃ in the presence of Fe₃O₄ nanofibers. CeO₂ shell was uniformly coated on the surface of Fe₃O₄ nanofibers to form a unique core‐shell structure, while Au NPs were encapsulated inside the CeO₂ shell. The as‐prepared Fe₃O₄‐Au@CeO₂ hybrid nanofibers have been proved to be positively surface charged due to the formation of CeO₂ shell, enabling them to be good candidates for predominant selective catalytic activity towards the degradation of negatively charged organic dyes. In addition, the Fe₃O₄‐Au@CeO₂ hybrid nanofibers showed magnetic properties, offering them excellent recyclable usability. This work presents a facile and effective solution to prepare magnetic noble metal/metal oxide hybrid nanomaterials with unique chemical structure and surface characteristic for promising applications in heterogeneous catalysis.     

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe3O4 hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

In this report, we introduced Graphene oxide‐iron oxide (GO‐Fe₃O₄) nanocomposites as a heterogeneous catalyst for arylation/alkylation of benzothiazoles with aldehydes and benzylic alcohols in the presence of diisopropyl azodicarboxylate (DIAD) as an oxidant which exclusively produced 2‐aryl (alkyl)‐1H–benzothizoles in moderate to excellent yields. The absence of precious metals and toxic solvent, easy product isolation, and recyclability of the GO‐Fe₃O₄ with no loss of activity are notable advantages of this method.     

Synthesis,characterization, and properties of monodispersed magnetite coated multi‐walled carbon nanotube/polypyrrole nanocomposites synthesized by in‐situ chemical oxidative polymerization

This study describes the preparation of a nanocomposites fabricated from monodispersed 4‐nm iron oxide (Fe₃O₄) coated on the surface of carboxylic acid containing multi‐walled carbon nanotube (c‐MWCNT) and polypyrrole (PPy) by in situ chemical oxidative polymerization. High‐resolution transmission electron microscopy images and X‐ray diffraction (XRD) data indicate that the resulting Fe₃O₄ nanoparticles synthesized using the thermal decomposition are close to spherical dots with a particle size about 4 ± 0.2 nm. The resulting nanoparticles were further mixed with c‐MWCNT in an aqueous solution containing with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form one‐dimensional Fe₃O₄ coated c‐MWCNT template for further preparation of nanocomposite. Structural and morphological analysis using field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, and XRD showed that the fabricated Fe₃O₄ coated c‐MWCNT/PPy nanocomposites are one‐dimensional core (Fe₃O₄ coated c‐MWCNT)‐shell (PPy) structures. The conductivities of these Fe₃O₄ coated c‐MWCNT/PPy nanocomposites are about four times higher than those of pure PPy matrix. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 727–733, 2008     

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide,Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe₃O₄NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe₃O₄@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review’s main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.     

Preparation of novel hybrid nanomaterials based on LaFeO3 and phosphotungstic acid as a highly efficient magnetic photocatalyst for the degradation of methylene blue dye solution

Novel magnetic hybrid nanomaterials 1 (LaFeO₃.Fe₃O₄@SiO₂-NH₂/PW₁₂) were synthesized by supporting phosphotungstic acid (H₃PW₁₂O₄₀; PW₁₂) on LaFeO₃.Fe₃O₄ nanomaterials through sono-assisted method. The synthesized nanomaterials were fully characterized by using FT-IR, XRD, UV–vis, BET-BJH, VSM, SEM, and TEM analyses. FT-IR, XRD, and UV–vis confirmed successful synthesis of nanomaterials. The SEM and TEM images revealed spherical morphology with core-shell structure for hybrid nanomaterials 1 . VSM results confirmed the magnetic property of hybrid nanomaterials 1 and suggested it as easily recyclable photocatalyst for removal of organic dyes from aqueous solution. The photocatalytic activity of hybrid nanomaterials 1 has been studied over the degradation of methylene blue (MB) and methyl orange (MO) solution under UV–vis light irradiation. Importantly the hybrid nanomaterials 1 showed outstanding degradation efficiency for MB solution in comparison with bare LaFeO₃.Fe₃O₄ and PW₁₂. The photocatalytic activity was enhanced mainly due to the high efficiency in separation of electron–hole pairs induced by the remarkable synergistic effects of LaFeO₃.Fe₃O₄ and PW₁₂ semiconductors. After the photocatalytic reaction, the nanocomposite can be easily separated from the reaction solution and reused several times without loss of its photocatalytic activity. Trapping experiments indicated that hole (h_VB⁺) and ^•OH radicals were the main reactive species for dye degradation in the present photocatalytic system. On the basis of the experimental results and estimated band gaps, the mechanism for the enhanced photocatalytic activity was proposed.     

Synthesis of Co/MFe2O4 (M=Fe, Mn) core/shell nanocomposite particles

Monodispersed cobalt nanoparticles (NPs) with controllable size (8–14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe₂O₄ (M=Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe₂O₄ nanocomposites are prepared with tunable shell thickness (1–5 nm). The Co/MFe₂O₄ nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Compared to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications.     

Bacitracin‐Conjugated Superparamagnetic Iron Oxide Nanoparticles: Synthesis,Characterization and Antibacterial Activity

Bacitracin‐conjugated superparamagnetic iron oxide (Fe₃O₄) nanoparticles were prepared by click chemistry and their antibacterial activity was investigated. After functionalization with hydrophilic and biocompatible poly(acrylic acid), water‐soluble Fe₃O₄ nanoparticles were obtained. Propargylated Fe₃O₄ nanoparticles were then synthesized by carbodiimide reaction of propargylamine with the carboxyl groups on the surface of the iron oxide nanoparticles. By further reaction with N₃‐bacitracin in a Cu^I‐catalyzed azide–alkyne cycloaddition, the magnetic Fe₃O₄ nanoparticles were modified with the peptide bacitracin. The functionalized magnetic nanoparticles were characterized by powder X‐ray diffraction, X‐ray photoelectron spectroscopy, TEM, zeta‐potential analysis, FTIR spectroscopy and vibrating‐sample magnetometry. Cell cytotoxicity tests indicate that bacitracin‐conjugated Fe₃O₄ nanoparticles show very low cytotoxicity to human fibroblast cells, even at relatively high concentrations. In view of the antibacterial activity of bacitracin, the biofunctionalized Fe₃O₄ nanoparticles exhibit an antibacterial effect against both Gram‐positive and Gram‐negative organisms, which is even higher than that of bacitracin itself. The enhanced antibacterial activity of the magnetic nanocomposites allows the dosage and the side effects of the antibiotic to be reduced. Due to the antibacterial effect and magnetism, the bacitracin‐functionalized magnetic nanoparticles have potential application in magnetic‐targeting biomedical applications.     

Electromagnetic properties of Fe3O4‐functionalized graphene and its composites with a conducting polymer

Hybrid materials of Fe₃O₄‐decorated reduced graphene oxide (Fe₃O₄‐RGO) and poly(3,4‐ethylenedioxythiophene) (PEDOT) were prepared by poly(ionic liquid)‐mediated hybridization. In this hybrid material, poly(ionic liquid) was found to perform multiple roles for: (1) stabilizing Fe₃O₄‐RGO against aggregation in the reaction medium, (2) transferring Fe₃O₄‐RGO nanomaterials from aqueous into organic phase, and (3) associating Fe₃O₄‐RGO nanomaterials with PEDOT. The hybrid materials of Fe₃O₄‐RGO with PEDOT showed the lowest surface resistivity of 80 Ω sq^?1 at an RGO‐Fe₃O₄ loading of 1 wt %, and exhibited superparamagnetic behavior with an electromagnetic interference shielding effectiveness of 22 dB. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Au-Fe3O4 heterostructures for catalytic,analytical, and biomedical applications

Au-Fe₃O₄ heterostructures including dumbbell-like dimer, core-shell structure, and flower-type nanoparticles (NPs), attract much attention due to their multiple modifiable surfaces and unique properties coming from either Au or Fe₃O₄ nanoparticles. This review focuses on the preparation methods and biomedical applications of these heterogenous NPs in the fields of catalysis, assay, multimodal imaging, and combination therapy.     

Green and simple method for preparing iron oxide nanoparticles supported on mesoporous biochar as a Fenton catalyst

With the on-going development of nanotechnology, iron-containing nanomaterials have received much attention in wastewater treatment and site remediation. Here, we synthesized a biochar-supported iron oxide nanocomposite (Fe_mO_n/BC) by simply pyrolysing rice root, which is a natural source both of iron and carbon. The Fe_mO_n/BC nanocomposite nicely preserved the vascular bundle structure of rice root. With iron oxide doped on the mesoporous biocarbon, the composite has the usability as a Fenton-like catalyst in the Fenton system. Fe_mO_n/BC-700 (pyrolysis at 700 °C) was selected to catalysis the reactive brilliant red X-3B degradation. Under the same catalytic effect, the service life of Fe_mO_n/BC-700 almost doubles that of iron microparticles. We believe this green and energy-efficient method might have value in biomass usage and helps sustainable development.     

Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes

Iron(III) oxide is a low‐cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe₂O₃ with high surface area‐to‐volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4–5 nm γ‐Fe₂O₃ nanoparticles by a polymer‐assisted aggregating self‐assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open‐pore structure with high surface area (up to 167 m² g^?1) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ‐Fe₂O₃ to α‐Fe₂O₃ and to Fe₃O₄ under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large‐scale synthesis.     

A Facile Approach to Fabricate Water‐soluble Au‐Fe3O4 Nanoparticle for Liver Cancer Cells Imaging

Au‐Fe₃O₄ nanoparticles were widely used as nanoplatforms for biologic applications through readily further functionalization. Dopamine (DA)‐coated superparamagnetic iron oxide (SPIO) nanoparticles (DA@Fe₃O₄) have been successfully synthesized using a one‐step process by modified coprecipitation method. Then 2–3 nm gold nanoparticles were easily conjugated to DA@Fe₃O₄ nanoparticles by the electrostatic force between gold nanoparticles and amino groups of dopamine to afford water‐soluble Au‐Fe₃O₄ hybrid nanoparticles. A detailed investigation by dynamic light scatting (DLS), transmission electron microscopy (TEM), fourier transform infrared (FT‐IR) and X‐ray diffraction (XRD) were performed in order to characterize the physicochemical properties of the hybrid nanoparticles. The hybrid nanoparticles were easily functionalized with a targeted small peptide A54 (AGKGTPSLETTP) and fluorescence probe fluorescein isothiocyanate (FITC) for liver cancer cell BEL‐7402 imaging. This simple approach to prepare hybrid nanoparticles provides a facile nanoplatform for muti‐functional derivations and may be extended to the immobilization of other metals or bimolecular on SPIO surface.     

Investigation of thermal behaviour of hybrid nanostructures based on Fe2O3 and PAMAM dendrimers

Dendrimers or biofunctionalized dendrimers can be assembled onto magnetic iron oxide nanoparticles to stabilize or functionalize inorganic nanoparticles. Carboxylated poly(amidoamine) PAMAM dendrimers (generation 4.5) have been used for the synthesis of iron oxide nanoparticles, resulting nanocomposites with potential biomedical applications. The present paper aims to systematically investigate the thermal behaviour of nanostructured hybrids based on ferric oxide and PAMAM dendrimers, by differential scanning calorimetry (DSC) technique. The novelty consists both in synthesis procedure of hybrid nanostructures as well as in DSC approach of these nanocomposites. For the first time, we propose a new method to prepare Fe₂O₃??dendrimer nanocomposite, using soft chemical process at high pressure. Commercial PAMAM dendrimers with carboxylic groups on its surface were used. When high pressure is applied, polymeric structures suffer morphological changes leading to hybrid nanostructures' formation. In the same time, crystallinity of inorganic nanoparticles is provided. DSC results showed an increase in thermal stability of composites as compared to commercial dendrimers. This could be due to the formation of strong interactions between ferric oxide and carboxyl groups, as confirmed by Fourier transform infrared spectroscopy. Electron microscopy analysis (SEM/EDX) and size measurements were performed to demonstrate the existence of nanosized particles.     

Self-assembly approach for the synthesis of electro-magnetic functionalized Fe3O4/polyaniline nanocomposites: Effect of dopant on the properties

Electro-magnetic functionalized Fe₃O₄/polyaniline (PANI) nanocomposites were synthesized by chemical oxidative polymerization in the presence of ammonium peroxydisulfate as an oxidizing agent. Polymerization was carried out independently using two different types of dopants, organic acids (camphorsulfonic acid (CSA) and p-toluenesulfonic acid (TSA)) and inorganic acid (hydrochloric acid). A plausible mechanism for the formation of the nanocomposites (NCs) is presented. During the formation of NCs, CSA/TSA also serves as a micellar template, whereas micelle formation is absent in the case of HCl. Fe₃O₄/PANI-CSA-NC, Fe₃O₄/PANI-TSA-NC and Fe₃O₄/PANI-HCl-NC were characterized for morphology, molecular structure, electrical conductivity and magnetic properties by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–vis) and superconductor quantum interference device (SQUID) measurements. The results indicate that dopant influence the properties of the NCs. TEM photographs of Fe₃O₄/PANI-CSA and Fe₃O₄/PANI-TSA reveal that the composite particles are spherical having a layer of PANI-CSA or PANI-TSA over Fe₃O₄ nanoparticles. Fe₃O₄/PANI-CSA-NC and Fe₃O₄/PANI-TSA-NC have better morphology, conductivity and high magnetic saturation (M_s) than that of Fe₃O₄/PANI-HCl-NC. Under applied magnetic field, the NCs exhibit the hysteresis loops of the ferromagnetic behavior. M_s value varies with content of Fe₃O₄ present in the composites.     

Electrocatalytic Activity of Nanohybrids Based on Carbon Nanomaterials and MFe2O4 (M=Co,Mn) towards the Reduction of Hydrogen Peroxide

We report the advantages of hybrid nanomaterials prepared with electrogenerated ferrites (MFe₂O₄; M: Co, Mn) and multi‐walled carbon nanotubes (MWCNTs) or thermally reduced graphene oxide (TRGO) on the electro‐reduction of hydrogen peroxide. Glassy carbon electrodes (GCE) modified with these hybrid nanomaterials dispersed in Nafion/isopropanol demonstrated a clear synergism on the catalytic reduction of reduction of hydrogen peroxide at pH 13.00. The intimate interaction between MFe₂O₄ and carbon nanomaterials allowed a better electronic transfer and a facilitated regeneration of M²⁺ at the carbon nanomaterials, reducing the charge transfer resistances for hydrogen peroxide reduction and increasing the sensitivities of the amperometric response.     

Bio‐based hyperbranched polyurethane/Fe3O4 nanocomposites as shape memory materials

The bio‐based shape memory polymers have generated immense interest as advanced smart materials. Mesua ferrea L. seed oil‐based hyperbranched polyurethane (HBPU)/Fe₃O₄ nanocomposites were prepared by the in‐situ polymerization technique. The transmission electron microscopy confirmed the homogeneous distribution of the Fe₃O₄ nanoparticles in polymer matrix, whereas Fourier transform infrared spectroscopic study revealed the presence of strong interfacial interactions between them. The incorporation of Fe₃O₄ (0 to 10 wt%) into the HBPU resulted in an increase in tensile strength (5.5–15 MPa) and scratch resistance (3–6 kg). The thermo‐gravimetric analysis indicated the improvement of thermal stability (240–270°C) of the nanocomposites. The nanocomposites exhibited full shape fixity, as well as almost full shape recovery under the microwave stimulus. The shape recovery speed increased with the increase of Fe₃O₄ nanoparticles content in the nanocomposites. Thus, the studied nanocomposites might be used as advanced shape memory materials in different potential fields. Copyright © 2013 John Wiley & Sons, Ltd.     

A simplistic one-pot method to produce magnetic graphene-CdS nanocomposites

A simple, yet novel process was developed where magnetic graphene-CdS (Fe₃O₄-CdS/G) nanocomposites were prepared by a one-pot solvothermal route in which the reduction of graphite oxide (GO) into graphene was accompanied by the generation of CdS and Fe₃O₄ nanoparticles. The results of TEM and XRD studies indicate the formation of Fe₃O₄-CdS/G nanocomposites. Besides vibration sample magnetometry, fluorescence spectra and loading of doxorubicin (DOX) reveal that this new nanocomposite possesses good superparamagnet (44.85 emu/g), good fluorescent properties and a high loading efficiency (0.98 mg/mg). The efficient, stable, and water soluble nanocomposites are confirmed to be suitable for biomedical applications.