As-synthesized Fe3O4 Nanoparticles Research Articles

Citrus sinensis assisted biogenic synthesis and physicochemical properties of Fe3O4 nanoparticles for antibacterial activity

The biogenic synthesis of Fe3O4 nanoparticles was boosted by the use of a recently found organic acid produced from Citrus sinensis. Fe3O4 nanoparticles were synthesized at 350 °C and 450 °C, and their physical and chemical properties were studied using a number of different characterisation techniques. Crystalline structure and phase were determined by X-ray diffraction (XRD) analysis of as-synthesized and annealed Fe3O4 nanoparticles. This finding demonstrates that the Fe3O4 nanoparticles have a unique, cubic spinel structure with only one phase. With the use of well-established formulae, we were able to calculate the crystallite size and lattice parameter of the synthesized Fe3O4 nanoparticles, and found that their size increased as a function of the annealing temperature, from 11 nm to 34 nm. The FTIR method was used to analyse the as-synthesized and annealed Fe3O4 nanoparticles for functional groups, molecular structure, and chemical bonding. Metallic components at 465, 551 and 1628 cm−1 were found after analysing the three samples. Field Emission Scanning Electron Microscopy (FESEM) was used to analyse the surface morphology and grain size fluctuations of Fe3O4 nanoparticles, while Energy Dispersive X-ray Spectroscopy (EDX) was used to study the elemental composition. Fe3O4 nanoparticles' thermal characteristics change depending on the annealing temperature. The antibacterial efficacy of Fe3O4 nanoparticles, manufactured using green methods, was assessed against two different types of bacteria: Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative).

Drug delivery system based on magnetic iron oxide nanoparticles coated with (polyvinyl alcohol-zinc/aluminium-layered double hydroxide-sorafenib)

The structural, physicochemical, morphological, and magnetic properties of magnetic drug nanoparticles prepared using polymer, layered double hydroxide (LDHs) and drug as the coating agent and magnetic iron oxide nanoparticles (MNPs) as the core were systematically studied. Firstly, a co-precipitation method was employed to synthesize the Fe3O4 nanoparticles. Then, the surface was coated with polyvinyl alcohol, Zn/Al-LDH and sorafenib (SO). XRD and FTIR studies indicate that the core has the crystal structure of the iron oxide. The TGA results supported the existence of both the core and the shell. The saturation magnetization of the as-synthesized Fe3O4 nanoparticles was found to be reduced from 80 to57 emu/g when the nanoparticles were coated with polyvinyl alcohol, Zn/Al-LDH and the drug sorafenib. HRTEM images revealed that the mean dimension of the naked Fe3O4 nanoparticles is around 30 nm. Further structural characterizations showed that the addition of the shell led to the formation of uniform particles with a particle size distribution of about 95 nm. The kinetics of drug release from the nanoparticles was found to be governed by the pseudo-second-order equation. Cell viability assays clearly showed that the magnetic iron oxide nanoparticles coated with polyvinyl alcohol-sorafenib-Zn/Al-layered double hydroxide were found to be more potent than sorafenib alone against HepG2 liver cancer cells, while displayed no cytotoxicity against 3T3 fibroblasts. These results show that the coated Fe3O4 magnetite nanoparticles are a good candidate as a drug delivery carrier to be further explored for biomedical applications.

Peroxydisulfate activation by in-situ synthesized Fe3O4 nanoparticles for degradation of atrazine: Performance and mechanism

Herein activation of persoxydisulfate (PDS) was achieved by in-situ synthesized Fe3O4 nanoparticles (NPs) from a sacrificial iron anode in an electrochemical (EC) cell. The as-synthesized Fe3O4 NPs were characterized to be in spherical and in the nano size. The performance of the process, EC-Fe3O4/PDS, was investigated in terms of atrazine (ATZ) degradation. Optimum process conditions were determined as initial pH of 5, electrolyte (Na2SO4) concentration of 1 mM, a current density of 1.67 A m−2, PDS concentration of 0.5 mM and initial ATZ concentration of 10 mg L–1. At optimum conditions, the EC-Fe3O4/PDS process could effectively degrade 80% of ATZ in an aqueous solution within a short reaction time of 20 min. The electrical energy consumption of the process was found to be quite low with 0.0307 kWh/m3. Based on the LC/MS analysis, the degradation pathway of ATZ with seven transformation products was proposed. Finally, a possible mechanism of the EC-Fe3O4/PDS process was put forward, which includes the activation of PDS and the role of radicals in the degradation of ATZ. In conclusion, the combination of Fe3O4 NPs catalyzed PDS oxidation with the EC process was very effective in the degradation of ATZ to dechlorinated final products. The strong synergistic effect makes this process superior to conventional methods due to the high degradation efficiency with low electrical energy and chemical consumption. Application of this method, with very low current density, may not only minimize the electrical energy consumption but also help reduce the sludge production due to the lower iron dissolution.

Implementation of magnetic Fe3O4@ZIF-8 nanocomposite to activate sodium percarbonate for highly effective degradation of organic compound in aqueous solution

Here, as-synthesized Fe3O4 nanoparticles were incorporated into the zeolitic imidazolate framework (ZIF-8) lattice to activate sodium percarbonate (SPC) for degradation of methylene blue (MB). The reaction rate constant of Fe3O4@ZIF-8/SPC process (0.0632min−1) at acidic conditions (pH=3) was more than six times that of the Fe3O4/SPC system (0.009min−1). Decreasing the solute concentration, along with increasing SPC concentration and Fe3O4@ZIF-8 nanocomposite (NC) dosage, favored the catalytic degradation of MB. The Fe3O4@ZIF-8 NC after fifteen consecutive treatment processes showed the excellent stability with a negligible drop in the efficiency of the system (<10%). The reaction pathway was obtained via GC–MS analysis.

Synthesis of Fe3O4 nanoparticles with tunable sizes for the removal of Cr(VI) from aqueous solution

In this study, size-tunable magnetite (Fe3O4) nanocrystal spheres were promptly synthesized by a facile one-pot solvothermal process with the presence of triethanolamine as an additive. The as-synthesized Fe3O4 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometer. The results showed that the synthesized nanoparticles were in the size range of 30–350 nm, had well-defined Fe3O4 crystal phase, and had favorable saturation magnetization. The effects of various important parameters, such as initial Cr(VI) concentration, temperature, and pH, on the adsorption properties of the as-obtained Fe3O4 particles for the removal of Cr(VI) in aqueous solution were deeply analyzed and studied. The results confirmed that the adsorption efficiency was highly pH dependent, decreased with the increasing of initial concentration of Cr(VI), and increased with increasing temperature. The adsorption data were well fitted with the Langmuir isotherm. The maximum adsorption capacity calculated from the Langmuir isotherm was 56.625 mg g−1 at temperature of 35°C and pH of 2.0.

ROS-independent toxicity of Fe3O4 nanoparticles to yeast cells: Involvement of mitochondrial dysfunction

Fe3O4 nanoparticles, one kind of magnetic nanomaterials (NMs), are widely used in drug delivery, biological imaging, sensors, catalysts and pollution management. However, its toxicity to biological systems and related toxicity mechanisms remain to be explored. In this study, we investigate the effect of as-synthesized Fe3O4 nanoparticles on growth of Saccharomyces cerevisiae, an important model fungus. Growth inhibition assays showed that Fe3O4 nanoparticles remarkably inhibited yeast growth. Interestingly, this inhibitory effect was not attributed to the well-known plasma membrane damage, cell wall damage and ROS accumulation. Further investigations revealed that the nanoparticles strongly impaired mitochondrial functions, resulting in abnormal mitochondrial morphology, decreased mitochondrial membrane potential (MMP) and attenuated ATP production. Most importantly, the respiratory chain complex Ⅳ, rather than other respiratory chain complexes and ATP synthases, was found to be the main target of the nanoparticles. This study uncovers a novel ROS-independent toxicity mechanism of Fe3O4 nanoparticles to eukaryotic cells.

Microwave-assisted rapid synthesis of Fe3O4/poly(styrene-divinylbenzene-acrylic acid) polymeric magnetic composites and investigation of their structural and magnetic properties

We report a facile method for rapid synthesis of highly crystalline superparamagnetic Fe3O4 nanoparticles with crystallite size in the range of 25–33 nm via microwave synthesizer. The Fe3O4 stabilized with PVP was used to synthesize strong magnetized spherical polymeric magnetic composites (PMCs) in the range 0.3–1.5 µm via microwave irradiated emulsion polymerization using vinyl monomers. The influence of reaction time and the amount of reactive reagents on the structure, morphology, thermal stability and magnetic property of synthesized PMCs were examined. HR-TEM revealed the incorporation of superparamagnetic Fe3O4 nanoparticles in the cross-linked polymeric matrix of poly(styrene-divinylbenzene-acrylic acid). The synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior at 300 K with a high saturation magnetization 67.5 emu/g for MNP-3. Interestingly, the as-synthesized magnetically responsive PMCs [Fe3O4/P(St-DVB-AA)] exhibit ferromagnetic properties with enhanced saturation magnetization in the measured temperature interval of 10–350 K, which is in contrast with the superparamagnetic behavior of synthesized Fe3O4 nanoparticles. An excellent saturation magnetization 22.5 emu/g was noted for the composite PMC-10 loaded with ∼24% magnetic nanoparticles. Further, the as-synthesized Fe3O4 nanoparticles and polymer magnetic composites exhibit the charge ordering (Verwey transition) at low temperature in the range 30–41 K and 23–25 K, respectively.

Optimization of photochemical decomposition acetamiprid pesticide from aqueous solutions and effluent toxicity assessment by Pseudomonas aeruginosa BCRC using response surface methodology

Contamination of water resources by acetamiprid pesticide is considered one of the main environmental problems. The aim of this study was the optimization of acetamiprid removal from aqueous solutions by TiO2/Fe3O4/SiO2 nanocomposite using the response surface methodology (RSM) with toxicity assessment by Pseudomonas aeruginosa BCRC. To obtain the optimum condition for acetamiprid degradation using RSM and central composite design (CCD). The magnetic TiO2/Fe3O4/SiO2 nanocomposite was synthesized using co-precipitation and sol–gel methods. The surface morphology of the nanocomposite and magnetic properties of the as-synthesized Fe3O4 nanoparticles were characterised by scanning electron microscope and vibrating sample magnetometer, respectively. In this study, toxicity assessment tests have been carried out by determining the activity of dehydrogenase enzyme reducing Resazurin (RR) and colony forming unit (CFU) methods. According to CCD, quadratic optimal model with R2 = 0.99 was used. By analysis of variance, the most effective values of each factor were determined in each experiment. According to the results, the most optimal conditions for removal efficiency of acetamiprid (pH = 7.5, contact time = 65 min, and dose of nanoparticle 550 mg/L) was obtained at 76.55%. Effect concentration (EC50) for RR and CFU test were 1.950 and 2.050 mg/L, respectively. Based on the results obtained from the model, predicted response values showed high congruence with actual response values. And, the model was suitable for the experiment’s design conditions.

Magnetite Fe3O4 nanoparticles synthesis by wet chemical reduction and their characterization

The authors report the synthesis of Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its characterization. Ferric chloride hexa-hydrate (FeCl3 · 6H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the synthesized Fe3O4 nanoparticles was determined by energy dispersive analysis of x-rays technique. The x-ray diffraction (XRD) technique was used for structural characterization of the nanoparticles. The crystallite size of the nanoparticles was determined using XRD data employing Scherrer’s formula and Hall–Williamson’s plot. Surface morphology of as-synthesized Fe3O4 nanoparticles was studied by scanning electron microscopy. High resolution transmission electron microscopy analysis of the as-synthesized Fe3O4 nanoparticles showed narrow range of particles size distribution. The optical absorption of the synthesized Fe3O4 nanoparticles was studied by UV–vis–NIR spectroscopy. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique for absorption band study in the infrared region. The magnetic properties of the as-synthesized Fe3O4 nanoparticles were evaluated by vibrating sample magnetometer technique. The thermal stability of the as-synthesized Fe3O4 nanoparticles was studied by thermogravimetric technique. The obtained results are elaborated and discussed in details in this paper.

Sol–gel derived silica/chitosan/Fe3O4 nanocomposite for direct electrochemistry and hydrogen peroxide biosensing

A novel strategy to fabricate hydrogen peroxide third generation biosensor has been developed from sol–gel of silica/chitosan (SC) organic–inorganic hybrid material assimilated with iron oxide magnetic nanoparticles (Fe3O4). The large surface area of Fe3O4 and porous morphology of the SC composite facilitates a high loading of horseradish peroxidase (HRP). Moreover, the entrapped enzyme preserves its conformation and biofunctionality. The fabrication of hydrogen peroxide biosensor has been carried out by drop casting of the SC/F/HRP nanocomposite on glassy carbon electrode (GCE) for study of direct electrochemistry. The x-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) confirms the phase purity and particle size of as-synthesized Fe3O4 nanoparticles, respectively. The nanocomposite was characterized by UV–vis spectroscopy, fluorescence spectroscopy and Fourier transform infrared (FTIR) for the characteristic structure and conformation of enzyme. The surface topographies of the nanocomposite thin films were investigated by scanning electron microscopy (SEM). Dynamic light scattering (DLS) was used to determine the particle size distribution. The electrostatic interactions of the SC composite with Fe3O4 nanoparticles were studied by the zeta potential measurement. Electrochemical impedance spectroscopy (EIS) of the SC/F/HRP/GCE electrode displays Fe3O4 nanoparticles as an excellent candidate for electron transfer. The SC/F/HRP/GCE exhibited a pair of well-defined quasi reversible cyclic voltammetry peaks due to the redox couple of HRP-heme Fe (III)/Fe (II) in pH 7.0 potassium phosphate buffer. The biosensor was employed to detect H2O2 with linear range of 5 μM to 40 μM and detection limit of 5 μM. The sensor displays excellent selectivity, sensitivity, good reproducibility and long term stability.

Enhanced Magnetism in Highly Ordered Magnetite Nanoparticle‐Filled Nanohole Arrays

A new approach to develop highly ordered magnetite (Fe3O4) nanoparticle-patterned nanohole arrays with desirable magnetic properties for a variety of technological applications is presented. In this work, the sub-100 nm nanohole arrays are successfully fabricated from a pre-ceramic polymer mold using spin-on nanoprinting (SNAP). These nanoholes a then filled with monodispersed, spherical Fe3O4 nanoparticles of about 10 nm diameter using a novel magnetic drag and drop procedure. The nanohole arrays filled with magnetic nanoparticles a imaged using magnetic force microscopy (MFM). Magnetometry and MFM measurements reveal room temperature ferromagnetism in the Fe3O4-filled nanohole arrays, while the as-synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior. As revealed by MFM measurements, the enhanced magnetism in the Fe3O4-filled nanohole arrays originates mainly from the enhanced magnetic dipole interactions of Fe3 O4 nanoparticles within the nanoholes and between adjacent nanoholes. Nanoparticle filled nanohole arrays can be highly beneficial in magnetic data storage and other applications such as microwave devices and biosensor arrays that require tunable and anisotropic magnetic properties.

Sub-30 nm Fe3O4 and γ-Fe2O3 octahedral particles: preparation and microwave absorption properties

A simple low-cost hydrothermal method has been developed to fabricate uniformly dispersed octahedral Fe3O4 nanoparticles with tunable size. The particle size can be reduced to 20–30 nm under the effect of phosphate, meanwhile, the edetate disodium can improve the dispersivity of particles. High-resolution transmission electron microscope showed that the octahedral Fe3O4 nanoparticle was enclosed by eight (111) planes. Octahedral γ-Fe2O3 nanoparticles were obtained by reoxidizing the as-synthesized Fe3O4 nanoparticles. The microwave absorption properties of the octahedral Fe3O4 and γ-Fe2O3 nanoparticles were measured in the frequency range of 2–18 GHz. A minimum reflection loss of −28 dB was observed at 8.6 GHz for octahedral Fe3O4 nanoparticles.

Folate-conjugated Fe3O4 nanoparticles for in vivo tumor labeling

Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid (FA) ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging (MRI) target detection and magnetic hyperthermia.

Bifunctional Fe3O4@C/YVO4:Sm3+ composites with the core–shell structure

A novel Fe3O4@C/YVO4:Sm3+ composites with magnetic and luminescent properties were reported. Firstly, the as-synthesized Fe3O4 nanoparticles were coated by carbon as a shell via a simple hydrothermal method. Furthermore, the Fe3O4@C nanoparticles were modified by YVO4:Sm3+ phosphors through a simple sol–gel process to prepared the Fe3O4@C/YVO4:Sm3+ microspheres. The characterization of as-prepared products were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and vibrating sample magnetometer (VSM). It is shown that Fe3O4@C/YVO4:Sm3+ composites with well-crystallized and core–shell structure were prepared. Additionally, the Fe3O4@C/YVO4:Sm3+ composites show excellent magnetic properties (13 emu/g) and luminescent properties, which made the composites useful for applications in biomedical devices such as magnetic bio-separation and drug/gene delivery.

Characterization of stabilized porous magnetite core-shell nanogel composites based on crosslinked acrylamide/sodium acrylate copolymers

Stabilized and dispersed superparamagnetic porous nanogels based on sodium acrylate (AA-Na) and acrylamide (AM) in a surfactant-free aqueous system were synthesized via solution polymerization at room temperature. The formation of magnetite nanoparticles was confirmed and their properties characterized using Fourier transform infrared spectroscopy. Extensive characterization of the magnetic polymer particles using transmission electron microscopy (TEM), dynamic light scattering and zeta potential measurements revealed that Fe3O4 nanoparticles were incorporated into the shells of poly(AM/AA-Na). The average particle size was 5 – 8 nm as determined from TEM. AM/AA-Na nanoparticles with a diameter of about 11 nm were effectively assembled onto the negatively charged surface of the as-synthesized Fe3O4 nanoparticles via electrostatic interaction. Crosslinked magnetite nanocomposites were prepared by in situ development of surface-modified magnetite nanoparticles in an AM/AA-Na hydrogel. Scanning electron microscopy was used to study the surface morphology of the prepared composites. The morphology, phase composition and crystallinity of the prepared nanocomposites were characterized. Atomic force microscopy and argon adsorption – desorption measurements of Fe3O4.AM/AA indicated that the architecture of the polymer network can be a hollow porous sphere or a solid phase, depending on the AA-Na content. c � 2013 Society of Chemical Industry

Facilely preparation and microwave absorption properties of Fe3O4 nanoparticles

The Fe3O4 nanoparticles were prepared by a novel wet-chemical method which shows its highly synthesizing efficiency and controllability. A possible formation mechanism was also proposed to explain the synthesizing process. X-ray diffraction (XRD) and transmission electron microscope (TEM) were employed and yielded an examination of an average diameter of 77nm of the as-synthesized Fe3O4 nanoparticles with face-centered cubic structure. Vibrating sample magnetometer (VSM) and vector network analyzer were employed to measure the magnetic property and electromagnetic parameters of the nanoparticles, then reflection losses (RL (dB)) were calculated in the frequency range of 2–18GHz. A large saturation magnetization (72.36emu/g) and high coercivity (95Oe) were determined and indicated that the Fe3O4 nanoparticles own strong magnetic performance. Following simulation results showed that the lowest reflection loss of the sample was −21.2dB at 5.6GHz with layer thickness of 6mm. Effect of nanometer-sized further provided an explanation for the excellent microwave absorption behavior shown by the Fe3O4 nanoparticles.

Al-doped Fe3O4 Nanoparticles and Their Magnetic Properties

Al-doped Fe3O4 nanoparticles were synthesized for the first time via the Composite-Hydroxide-Mediated (CHM) method from Fe3O4 and Al2O3 without using any capping agent. The synthesis technique was one-step and cost effective. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS). Samples with a tunable size of 500–1500 nm, 200–800 nm, and 100–700 nm could be obtained by adjusting the reaction time and temperature. Magnetic property of the as-synthesized Al-doped Fe3O4 nanoparticles was investigated. Magnetic hysteresis loops measured in the field range of −10 kOe<H<10 kOe, indicated the ferromagnetic behavior with coercivity (H c) of 470 and 110 Oe and remanence magnetization (M r) of 13 and 6.4 emu/g at the temperature of 5 and 300 K, respectively. The saturation intensity (M s) was 46.1 emu/g at 5 K, while it was about 43.6 emu/g at 300 K.

Size-controlled synthesis of magnetite nanoparticles.

Monodisperse magnetite nanoparticles have been synthesized by high-temperature solution-phase reaction of Fe(acac)3 in phenyl ether with alcohol, oleic acid, and oleylamine. Seed-mediated growth is used to control Fe3O4 nanoparticle size, and variously sized nanoparticles from 3 to 20 nm have been produced. The as-synthesized Fe3O4 nanoparticles have inverse spinel structure, and their assemblies can be transformed into gamma-Fe2O3 or alpha-Fe nanoparticle assemblies, depending on the annealing conditions. The reported procedure can be used as a general approach to various ferrite nanoparticles and nanoparticle superlattices.