Superparamagnetic γ-Fe2O3 Nanoparticles Research Articles

Optimizing degradation conditions of treatment of TATB explosive wastewater by γ-Fe2O3 nanoparticles and UV synergistic degradation

In this work, the effect of superparamagnetic γ-Fe2O3 nanoparticles and ultraviolet light (UV) synergistic degradation on the treatment of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) explosive wastewater was studied. γ-Fe2O3 nanoparticles were prepared by hydrolysis method and the degradation performance of TATB explosive wastewater was systematically studied with UV light assisted. The results showed that γ-Fe2O3 magnetic nanoparticles have a low size distribution that ranged from 5 to 10 nm and possesses superparamagnetic properties. The optimized degradation condition was investigated and best degradation performance was obtained with the optimized conditions: the initial of pH = 3, UV illumination intensity (5 w/cm2), reaction temperature (25 °C), initial total organic carbon concentration (4.025 mg/L) as well as reaction time (60 min). This work can offer a new idea to degrade the explosive wastewater.

Combining Ag and γ-Fe2O3 properties to produce effective antibacterial nanocomposites

The antibacterial activity of hybrid γ-Fe2O3/Ag nanocomposites against the bacterial pathogens E. coli (Gram-negative) and S. aureus (Gram-positive) has been studied. Silver is a well-known bactericidal agent and γ-Fe2O3 nanoparticles release heat when they are exposed to alternating magnetic fields. The combination of both properties to fight infections has not been previously explored. The nanocomposites were synthesized through reduction of silver nitrate in the presence of pre-synthesized superparamagnetic γ-Fe2O3 nanoparticles. Changing systematically the ratio of γ-Fe2O3 and silver precursor and the temperature of the reaction allowed obtaining superparamagnetic nanocomposites with different Ag contents and particle sizes. The antibacterial activity of the samples was tested, and the minimum inhibitory concentrations and minimum bactericidal concentrations of the nanocomposites were determined to compare the microbicidal activity of the samples. It was found that it is related with the release of silver ions from the nanocomposites. Finally, we studied the combination of the bactericidal effect of silver and magnetic hyperthermia finding a synergetic effect between them when plates containing E. coli or S. aureus bacteria with γ-Fe2O3/Ag nanocomposites were subjected to an alternating magnetic field. This effect is related with an increase in the release of silver ions due to that heat dissipation.

Synthesis of Trisubstituted 1,3-Thiazoles Using Gly-Pro-Glu (Tripeptide) Supported on Superparamagnetic Silica-Encapsulated γ-Fe2O3 Nanoparticles through Efficient Multi-Component Reaction in Water

Gly-Pro-Glu tripeptide supported on superparamagnetic silica-encapsulated γ-Fe2O3 nanoparticles -used as a magnetically recyclable heterogeneous catalyst- was synthesized. The catalyst was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectrum (EDS), thermo-gravimetric analysis (TGA), vibrating sample magnetometry (VSM), and Fourier transform infrared spectroscopy (FT-IR). MNPs-Gly-Pro-Glu was applied for the efficient synthesis of trisubstituted 1,3-thiazole derivatives. The catalyst demonstrated a superior catalytic activity toward the green one-pot synthesis of trisubstituted 1,3-thiazole via three-component reactions between arylglyoxals, cyclic-1,3-dicarbonyls and thiobenzamides in water. More importantly, the synthesized catalyst was separated easily by using an external magnet and was reused for ten runs without intense loss of catalytic activity.

Autodegradable clusters made from superparamagnetic nanoparticles with drug-release properties.

Aim: The agglomeration of nanoparticles plays an important role in the preparation of nanostructured materials, which has implications in their practical applications such as plasma nanosensor and drug release. Materials & methods: Highly stable individual superparamagnetic γ-Fe2O3 nanoparticles with diameter of 5nm were first synthesized in water. These particles were then assembled into spherical clusters with diameters of approximately 200nm using a simple and versatile method. Results: The prepared γ-Fe2O3 nanoparticle-based clusters were then used for aminophylline drug loading and release properties investigation. The results show the high drug load rate, release speed and release rate. Conclusion: The present materials and method present great potential in drug-release application.

Crystallization of magnetic particles in nNa2O-9SrO-6Fe2O3-8B2O3 (n = 1 and 4) glasses

Abstract Magnetic glass-ceramics with composition nNa2O-9SrO-6Fe2O3-8B2O3 (n = 1 and 4) were prepared by fast quenching of the molten oxide mixtures and subsequent thermal treatment of the obtained glasses at 450–950 °C. The samples were investigated by differential thermal analysis, x-ray powder diffraction, electron microscopy, and SQIUD magnetometry. Increasing of the sodium oxide content leads to a significant decrease of the glass transition, devitrification, and melting temperatures. Just above the glass transition temperature (525 °C for n = 1 and 430 °C for n = 4) superparamagnetic γ-Fe2O3 nanoparticles precipitate, which, at elevating annealing temperature, are substituted by thin hexaferrite nanoplatelets with coercivities of 2000–4000 Oe; the annealing at higher temperatures results in crystallization of the submicron hexaferrite particles with a coercivity of up to 6000 Oe. Thus the glass-ceramics are highly applicable sources of non-sintered nanoparticles with various morphologies and magnetic properties.

Magnetic Regulation of Thermo-Chemotherapy from a Cucurbit[7]uril-Crosslinked Hybrid Hydrogel.

The fabrication, characterization, and therapy efficiency of a noncovalent-bonded hydrogel network, which is assembled by utilizing cucurbit[7]uril as a supramolecular linker to "stick" superparamagnetic γ-Fe2 O3 nanoparticles onto the polymer backbone of catechol-functionalized chitosan are described. The unique barrel-shaped structure of cucurbit[7]uril not only facilitates host-guest recognition with the catechol derivatives, but also forms robust electrostatic interactions between its carbonyl portals and the γ-Fe2 O3 nanoparticles in a supramolecular manner, which leaves the physical and chemical properties of the nanoparticles intact. The γ-Fe2 O3 nanoparticles display vibrational movement and heat generation under an alternating magnetic field, endowing the formed hybrid supramolecular hydrogel with both thermo- and chemotherapy modalities, which are demonstrated both in vitro and in vivo. Here, a facile strategy is introduced to construct noncovalent interactions between a polymer matrix and the incorporated nanoparticles, which is amendable to a wide range of biomedical and industrial applications.

Fluorescent magnetic PEI-PLGA nanoparticles loaded with paclitaxel for concurrent cell imaging, enhanced apoptosis and autophagy in human brain cancer.

Magnetic nanoparticles are regarded as a promising drug delivery vehicle with the improved efficacy and lowered side effects for antitumor therapy. Herein, the poly lactic-co-glycolic acid (PLGA) modified magnetic nanoplatform was synthesized using superparamagnetic γ-Fe2O3 nanoparticles (MNPs) as a core, and then labelled with polyethylenimine (PEI)-conjugated fluorescein isothiocyanate (FITC), and simultaneously loaded with antitumor drug paclitaxel (PTX) for theranostic analysis of antitumor effects investigated in human brain glioblastoma U251 cells. As a result, the prepared PEI-PLGA-MNPs showed a relatively round sphere with an average size of 80 nm approximately, and the FITC-labeling PEI-PLGA-MNPs were efficiently endocytosed by the U251 cells for cellular imaging. Moreover, the fabricated PEI-PLGA-PTX-MNPs also demonstrated an inhibition of the targeted cell proliferation and migration, and a programmed cell death, via both apoptosis modulating by a burst of reactive oxygen species (ROS) and autophagy with accumulation of autophagosomes and LC3-II signals detected in the treated glioblastoma U251 cells after uptaking. Therefore, the constructed nanoplatform could be effectively applied for simultaneous cellular imaging and drug delivery in human brain glioblastoma treatment in future.

Fabrication of superparamagnetic nanofibrous poly(l-lactic acid)/γ-Fe2 O3 microspheres for cell carriers.

Nanofibrous poly(l-lactic acid) (PLLA) microspheres are extensively studied to be used as cell carriers in the field of tissue engineering because the unique structure can promote cell proliferation and migration. But as injectable scaffold materials, PLLA microspheres easily run off to the soft tissue space because of the lack of cohesive force. It will affect the treatment efficiency and even cause additional inflammatory response. In order to overcome this disadvantage, superparamagnetic γ-Fe2 O3 nanoparticles assisted with oxidative polymerization of dopamine were used for surface modification of PLLA microspheres in this study. The results showed that this surface modification had no obvious cytotoxicity, and the modified microspheres possessed the ability to carry seed cells to controllably move to the defect sites with the guidance of magnetic field, which may be able to increase the repair efficiency. Moreover, the characteristic nanofibrous structure was not destroyed after modification, which was able to promote biological activity of cells. This work provides a novel way to produce superparamagnetic nanofibrous microspheres designed for cell microcarriers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 511-520, 2019.

Bare and polymer coated iron oxide superparamagnetic nanoparticles for effective removal of U (VI) from acidic and neutral aqueous medium

Superparamagnetic γ-Fe2O3 nanoparticles (5 nm diameter) were synthesized in water. The bare particles exhibit good colloidal stability at ∼pH 2 because of the strong electrostatic repulsion with a surface charge of +25 mV. The polyacrylic acid (PAA)-coated particles exhibit remarkable colloidal stability at ∼pH 7 with abundant free carboxyl groups as reactive sites for subsequent functionalization. In this work, we used zeta potential analysis, transmission electron microscopy, small angle X-ray scattering, and Inductively coupled plasma mass spectrometry to investigate the adsorption behavior of U (VI) on bare and coated colloidal superparamagnetic nanoparticles at pH 2 and pH 7. At pH 2, uranyl ion (UO22+) absorbed on the surface of the bare particles with decreasing particle surface charge. This induced particle agglomeration. At pH 7, uranyl ion (UO22+) hydrolyzed and formed plate-like particles of uranium hydroxide that were ∼50 nm in diameter. The PAA-coated iron oxide nanoparticles absorbed on the surface of these U (VI) hydroxide plates to form large aggregates that precipitate to the bottom of the dispersion. At both pH 2 and pH 7, the resulting U (VI)/nanoparticle complex can be easily collected and extracted from the aqueous environment via an external magnetic field. The results show that both bare and polymer-coated superparamagnetic γ-Fe2O3 nanoparticles are potential absorbents for removing U (VI) from water.

Synthesis and in vitro experiments of carcinoma vascular endothelial targeting polymeric nano-micelles combining small particle size and supermagnetic sensitivity

Objective: To construct carcinoma vascular endothelial-targeted polymeric nanomicelles with high magnetic resonance imaging (MRI) sensitivity and to evaluate their biological safety and in vitro tumor-targeting effect, and to monitor their feasibility using clinical MRI scanner.Method: Amphiphilic block copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) was synthesized via the ring-opening polymerization of ε-caprolactone (CL) initiated by poly(ethylene glycol) (PEG), in which cyclic pentapeptide Arg-Gly-Asp (cRGD) was conjugated with the terminal of hydrophilic PEG block. During the self-assembly of PEG-PCL micelles, superparamagnetic γ-Fe2O3 nanoparticles (11 nm) was loaded into the hydrophobic core. The cRGD-terminated γ-Fe2O3-loaded polymeric micelles targeting to carcinoma vascular endothelial cells, were characterized in particle size, morphology, loading efficiency and so on, especially high MRI sensitivity in vitro. Normal hepatic vascular endothelial cells (ED25) were incubated with the resulting micelles for assessing their safety. Human hepatic carcinoma vascular endothelial cells (T3A) were cultured with the resulting micelles to assess the micelle uptake using Prussian blue staining and the cell signal intensity using MRI.Results: All the polymeric micelles exhibited ultra-small particle sizes with approximately 50 nm, high relaxation rate, and low toxicity even at high iron concentrations. More blue-stained iron particles were present in the targeting group than the non-targeting and competitive inhibition groups. In vitro MRI showed T2WI and T2 relaxation times were significantly lower in the targeting group than in the other two groups.Conclusion: γ-Fe2O3-loaded PEG-PCL micelles not only possess ultra-small size and high superparamagnetic sensitivity, also can be actively targeted to carcinoma vascular endothelial cells by tumor-targeted cRGD. It appears to be a promising contrast agent for tumor-targeted imaging.

Smooth and rapid microwave synthesis of MIL-53(Fe) including superparamagnetic [formula omitted] nanoparticles

MIL-53(Fe) linked to superparamagnetic γ-Fe2O3 nanoparticles was created using time-efficient microwave synthesis. Intermediates as well as the final product have been characterized by Dynamic Light Scattering (DLS), Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA). It is found that this route allows the production of Fe nanoparticles with typical sizes of about 80nm that are embedded inside the metal-organic structures. Detailed magnetization measurements using SQUID magnetometry revealed a nearly reversible magnetization loop indicating essentially superparamagnetic behavior.

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300K). It has been shown that the model based on the spin value S=30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles.

Thermal transformation of water-dispersible magnetite nanoparticles

Thermal transformation of water-dispersible magnetite (Fe3O4) nanoparticles formed by the thermal decomposition of [Fe(NH2CONH2)6](NO3)3 in triethylene glycol (TEG) was studied to explore the possibilities of the synthesis of water-dispersible maghemite (γ-Fe2O3) using X-ray diffraction, differential thermal analysis, thermogravimetric analysis, and Fourier transformed infrared spectroscopy. The structural and magnetic properties of resulting γ-Fe2O3 nanoparticles were characterized using N2 adsorption–desorption, transmission electron microscopy, UV–Vis absorption spectroscopy, and vibrating sample magnetic measurements. The results show that the oxidation of Fe3O4 nanoparticles at 150 °C for 6 h can produce superparamagnetic γ-Fe2O3 nanoparticles less than 10 nm in size coated with a TEG layer. The obtained γ-Fe2O3 nanoparticles are highly dispersible in water owing to the hydrophilic properties of the TEG coating.

Size-Controlled Pd Nanoparticle Catalysts Prepared by Galvanic Displacement into a Porous Si-Iron Oxide Nanoparticle Host.

Porous silicon nanoparticles containing both Pd and iron oxide nanoparticles are prepared and studied as magnetically recoverable catalysts for organic reductions. The Pd nanoparticles are generated in situ by electroless deposition of Pd(NH3)42+, where the porous Si skeleton acts as both a template and as a reducing agent and the released ammonia ligands raise the local pH to exert control over the size of the Pd nanoparticles. The nanocomposites are characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, nitrogen adsorption, X-ray diffraction, superconducting quantum interference device magnetization, and dynamic light scattering. The nanocomposite consists of a porous Si nanoparticle (150 nm mean diameter) containing ∼20 nm pores, uniformly decorated with a high loading of surfactant-free Pd nanoparticles (12 nm mean diameter) and superparamagnetic γ-Fe2O3 nanoparticles (∼7 nm mean diameter). The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride is catalyzed by the nanocomposite, which is stable through the course of the reaction. Catalytic reduction of the organic dyes methylene blue and rhodamine B is also demonstrated. The conversion efficiency and catalytic activity are found to be superior to a commercial Pd/C catalyst compared under comparable reaction conditions. The composite catalyst can be recovered from the reaction mixture by applying an external magnetic field due to the existence of the superparamagnetic iron oxide nanoparticles in the construct. The recovered particles retain their catalytic activity.

Superparamagnetic γ-Fe2O3nanoparticles as an easily recoverable catalyst for the chemical recycling of PET

There have been numerous studies to develop catalysts for the chemical recycling of poly(ethylene terephthalate) (PET) via glycolysis. However, in the field of PET glycolysis, only a few have attempted to recover and reuse the catalysts. This research utilized easily recoverable superparamagnetic γ-Fe2O3 nanoparticles as a reusable catalyst for PET glycolysis. γ-Fe2O3 nanoparticles were produced by calcining Fe3O4 nanoparticles prepared by the co-precipitation method. The produced γ-Fe2O3 nanoparticles had an average size of 10.5 ± 1.4 nm, and a very high surface area reaching 147 m2 g−1. Its superparamagnetic property was also confirmed. Glycolysis reactions were carried out, and the γ-Fe2O3 catalysts were recovered after the reactions by simple magnetic decantation. The use of magnetic iron oxide allowed the easy recovery of the catalyst from the glycolysis products. At 300 °C and a 0.05 catalyst/PET weight ratio, the maximum bis(2-hydroxyethlyl) terephthalate (BHET) monomer yield reached more than 90% in 60 min. At 255 °C and a 0.10 catalyst/PET weight ratio, the BHET yield reached more than 80% in 80 min. The catalyst was reused 10 times, giving almost the same BHET yield each time.

Super-paramagnetic responsive nanofibrous scaffolds under static magnetic field enhance osteogenesis for bone repair in vivo

A novel nanofibrous composite scaffold composed of super-paramagnetic γ-Fe2O3 nanoparticles (MNP), hydroxyapatite nanoparticles (nHA) and poly lactide acid (PLA) was prepared using electrospinning technique. The scaffold well responds extern static magnetic field with typical saturation magnetization value of 0.049 emu/g as well as possesses nanofibrous architecture. The scaffolds were implanted in white rabbit model of lumbar transverse defects. Permanent magnets are fixed in the rabbit cages to provide static magnetic field for the rabbits post surgery. Results show that MNP incorporated in the nanofibers endows the scaffolds super-paramagnetic responsive under the applied static magnetic field, which accelerates new bone tissue formation and remodeling in the rabbit defect. The scaffold also exhibits good compatibility of CK, Cr, ALT and ALP within normal limits in the serum within 110 days post implantation. In conclusion, the super-paramagnetic responding scaffold with applying of external magnetic field provides a novel strategy for scaffold-guided bone repair.

Facile synthesis and catalytic application of Ag–Fe2O3–carbons nanocomposites

We present a facile and mild synthetic strategy for preparing the Ag–Fe2O3–carbons nanocomposites (Ag-MACs) via γ-ray, in which the superparamagnetic γ-Fe2O3 and silver nanoparticles are randomly dispersed in the porous carbons. The results show that Ag-MACs have large surface area (654m2/g) and superparamagnetism. Meanwhile, we also study the application of Ag-MACs in the catalytic reduction of 4-nitrophenol to 4-aminophenol. Experimental results show Ag-MACs have high catalytic reduction capacity and can be separated from the water easily by the magnet for the reuse. In addition, the initial concentration of silver nitrate is determined for the maximum reaction rate.

A facile approach to superparamagnetic porous carbons and its high capability for the removal of pollutants in water

We present a facile and mild synthetic strategy for preparing superparamagnetic porous carbons via γ-ray, in which the superparamagnetic γ-Fe2O3 nanoparticles are randomly dispersed in the porous carbons. The magnetic porous carbon materials have large surface area (844m2/g) and large pore volume (0.86cm3/g). Meanwhile, the saturation magnetization can be tunable by changing the initial amount of iron salt. We also study the application of magnetic porous carbon materials in the removal of organic pollutants in water. Experimental results show that the magnetic porous materials have high capacity of removing the pollutants and can be separated from the water easily by the magnet.

Controlled Assembly of Ultrasmall Iron Oxide Nanoparticles on Carbon Nanotubes: Facile Preparation and Interfacially Induced Ferromagnetism

Abstract Ultrasmall (<5 nm) γ-Fe2O3 nanocrystals with tunable loading density on the carbon nanotubes (CNTs) were solvothermally synthesized using bifunctional phenol as capping ligand and dually as surfactant that favored uniform attachment. With the interfacial charge transfer, the nanosize-dependently superparamagnetic γ-Fe2O3 nanoparticles transform to weak ferromagnetism at room temperature.

X-ray photoelectron and Mössbauer spectroscopy studies of bimetallic 57Fe-Pd nanocomposites prepared by metal-vapor synthesis

X-ray photoelectron and Mossbauer spectroscopy were used to study the composition and structure of 57Fe-Pd bimetallic black and 57Fe-Pd/SiO2 nanocomposites prepared by metal-vapor synthesis. The main parameters of the core level photoelectron spectra of 57Fe-Pd systems were determined. The bimetallic system was shown to be a disordered amorphous structure consisting of Pd particles, superparamagnetic γ-Fe2O3 nanoparticles with size 8–10 nm, and a Fe-O-Pd solid solution. Considerable broadening of Pd 3d peaks in 57Fe-Pd/SiO2 and an increase in the O 1s-Si 2p energy interval by 0.4 eV with respect to the spectrum of initial SiO2 were observed; this was evidence of the interaction of Pd with the support. The binding energy of Fe 2p3/2 peak in the nanocomposite spectrum was close to that of Fe2O3, but had a smaller width of the satellite peak and a larger spin-orbit splitting, which was indicative of a considerable amount of FeOOH on the surface compared with the other iron oxides.