Superparamagnetic γ-Fe2O3 Research Articles

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.

γ-Fe2O3@SiO2@4-(sulfoamino)butanoic acid as a novel superparamagnetic nanocatalyst promoted green synthesis of 5-(aryl)-5H-spiro[diindeno[1,2-b:2′,1′-e]pyridine-11,3′-indoline]-2′,10,12-trione derivatives

Grafting of 4-(sulfoamino)butanoic acid on superparamagnetic γ-Fe2O3@SiO2 nanoparticles afforded γ-Fe2O3@SiO2@4-(sulfoamino)butanoic acid as a novel heterogeneous nanocatalyst, which was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, field emission scanning electron microscopy, and thermal gravimetric analysis. In this research, we report a convenient and one-pot efficient direct protocol for the pseudo four-component preparation of 5-(aryl)-5H-spiro[diindeno[1,2-b:2′,1′-e]pyridine-11,3′-indoline]-2′,10,12-trione derivatives via cascade condensation reaction of 1,3-indandione and isatins with various aromatic amine in the presence of the catalytic amount of γ-Fe2O3@SiO2@4-(sulfoamino)butanoic acid under green conditions in aqueous media. This procedure offers several advantages such as: very easy reaction conditions, simple work-up, or purification, excellent yields, high purity of the desired product, atom economy, and short reaction times. The superparamagnetic catalyst is magnetically separable and retained chemical stability after recycling for at least five consecutive runs without detectable activity loss.

Facile bulk preparation and structural characterization of agglomerated γ-Fe2O3/SiO2 nanocomposite particles for nucleic acids isolation and analysis

Two facile methods for bulk preparation of γ-Fe2O3/SiO2 agglomerated magnetic nanocomposite (MNC) particles for magnetic separation of nucleic acids (NAs) are compared together. Different silica coating approaches were used for iron oxide silanization: Stöber method and sodium silicate dense-liquid process. Additional thermal treatment at 750 °C provided thermal and structural stability to the MNCs. The structural characteristics, magnetic properties, size and morphology of the synthesized materials have been studied. To validate the synthesized materials, the MNCs were used for the isolation of nucleic acids from human buccal epithelium cells and two human biosamples (whole blood and plasma) with addition of pathogenic viruses. It was shown that the prepared near-micron sized agglomerates of superparamagnetic (Ms = 40–45 emu/g) γ-Fe2O3/SiO2 MNC particles are fully coated with silica. The synthesized materials combine the advantages of nanosized (superparamagnetism) and micron-sized objects (separability, average precipitation stability). Both types of the MNCs described in the paper have demonstrated similar effectiveness of NAs isolation, comparable with commercial MAGNO-sorb® total NAs isolation kit (InterLabService, Russia) used as a reference. The appropriate structural stability, high magnetization and proper purity of the isolated NAs (A260/A280 ratio near 1.9) make the studied MNCs promising materials for magnetic bioseparation.

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.

Direct Observation of Chemical Conversion from Fe3O4 to ε-Fe2O3 by a Nanosize Wet Process

e-iron oxide (e-Fe2O3) has drawn attention from the viewpoints of high-density magnetic recording and high-frequency millimeter wave absorption. To date, chemical conversion from Fe3O4 (magnetite) to e-Fe2O3 under wet process conditions have been difficult. Herein, we report that e-Fe2O3 could be obtained from Fe3O4 using a nanosize wet process. In the present method, 10 or 16 nm sized Fe3O4 nanocrystals are used as the precursor. Fe3O4 nanocrystals are embedded in a silica matrix and subsequently sintered around 1000 °C in air, resulting in the chemical conversion from Fe3O4 to e-Fe2O3 being confirmed. In the case of 10 nm sized Fe3O4 precursors, the sample consists of 16% e-Fe2O3 and 84% γ-Fe2O3, whereas in the case of 16 nm sized Fe3O4 precursors, the sample consists of 24% e-Fe2O3 and 76% γ-Fe2O3. The magnetic hysteresis loops of the samples are theoretically predicted using the large hysteresis loop of e-Fe2O3 and the magnetization curve of super-paramagnetic γ-Fe2O3. The experimental and predicted h...

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.

Improvement of magnetorheological greases with superparamagnetic nanoparticles

Magnetorheological greases (MRGs) is a viscoelastic suspension comprised of carbonyl iron (CI) particles in a thixotropic medium; grease, which able to solve the instability problem that occurs in oil medium like MRFs. The primary purpose introduction of superparamagnetic nanoparticles γ-Fe2O3 in MRGs suspension is to investigate the effect of additives toward MRGs characteristics. Two types of MRGs suspension with and without nanoparticles γ-Fe2O3 were prepared in the same CI particles concentration for comparison purpose. It was observed that MRGs with incorporated of 1 wt% nanoparticles γ-Fe2O3 showed an increment regarding magnetic properties. In the meantime, the off-state viscosity of MRGs containing nanoparticles γ-Fe2O3 was reduced, however, increased during on-state condition. This fact indicates that the interspaces between CI particles are filled by the nanoparticles γ-Fe2O3. Therefore, the introduction of the nanoparticles indirectly improved the MRGs properties.

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.

Maghemite/nitrogen-doped graphene hybrid material as a reusable bifunctional catalyst for glycolysis of polyethylene terephthalate

In this paper, we present superparamagnetic γ-Fe2O3/nitrogen-doped graphene hybrid material as an efficient and environment-friendly bifunctional catalyst for a sustainable polyethylene terephthalate chemical recycling. The presented catalyst exhibit superparamagnetic behavior because of the infinitely small coercivity arising from the negligible energy barrier in the hysteresis of the magnetization loop. By magnetic recovering of the catalyst, the danger of releasing harmful catalyst components to the environment is reduced and the process becomes more cost-effective and sustainable. To the best of our knowledge, bifunctional catalyst including acidic and basic sites have never been used in any glycolysis reactions, particularly for polyethylene terephthalate. The catalytic activity of nitrogen-doped graphene and γ-Fe2O3 are also investigated which show the synergetic catalytic activity of γ-Fe2O3/nitrogen-doped graphene nanocomposite.

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.

Design and characterization of lisinopril-loaded superparamagnetic nanoparticles as a new contrast agent for in vitro, in vivo MRI imaging, diagnose the tumors and drug delivery system.

Superparamagnetic γ-Fe2O3@SiO2@lisinopril (MNPs-Lisinopril) nanoparticles are T2 and T2* negative contrast agents for magnetic resonance imaging. In this work, we report the preparation of lisinopril-coated MNPs for the first time as new T2 and T2* negative contrast agent for in vitro and in vivo MRI imaging and demonstrate the potential it simultaneously for drug delivery system, diagnose the tumors and MRI contrast agent. Measurements on the relaxivities (r1, r2 and r2*) of the MNPs-Lisinopril were determined in deionized water (in vitro). Furthermore, after subcutaneous injection of the MNPs-Lisinopril into 4T1 (ATCC® CRL2539™) tumor in BALB/c mice, the relaxivities were determined by a 1.5 T MRI apparatus (in vivo). T2- and T2*-weighted MRI images of MNPs-Lisinopril showed that the MR signal intensity decreased significantly with increasing nanoparticle concentration in water. With measured r2 values up to 236.66 mM-1s -1, our MNPs-Lisinopril show better performance than commercial alternatives. Also we tested drug release of Lisinopril coated MNPs at two different pHs. The MNPs- Lisinopril is a pH-sensitive drug delivery system and releases different amounts of lisinopril from MNPs-Captopril in different pHs.

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.

Effect of O-methyl-β-cyclodextrin-modified magnetic nanoparticles on the uptake and extracellular level of l-glutamate in brain nerve terminals

Changes in cholesterol concentration in the plasma membrane of presynaptic nerve terminals nonspecifically modulate glutamate transport and homeostasis in the central nervous system. Reduction of the cholesterol content in isolated rat brain nerve terminals (synaptosomes) using cholesterol-depleting agents decreases the glutamate uptake and increases the extracellular level of glutamate in nerve terminals. Extraction of cholesterol from the plasma membrane and its further removal from the synaptosomes by external magnetic field can be achieved by means of magnetic nanoparticles with immobilized cholesterol-depleting agent such as O-methyl-β-cyclodextrin (MCD). A simple approach is developed for preparation of maghemite (γ-Fe2O3) nanoparticles containing chemically bonded MCD. The method is based on preparation of a silanization agent containing MCD. It is synthesized by the reaction of triethoxy(3-isocyanatopropyl)silane with MCD. Base-catalyzed silanization of superparamagnetic γ-Fe2O3 provides a relatively stable colloid product containing 48μmol of MCDg−1. MCD-modified γ-Fe2O3 nanoparticles decrease the initial rate of the uptake and accumulation of l-[14C]glutamate and increase the extracellular l-[14C]glutamate level in the preparation of nerve terminals. The effect of MCD-immobilized nanoparticles is the same as that of MCD solution; moreover, magnetic manipulation of the nanoparticles enables removal of bonded cholesterol.

Low temperature synthesized ultrathin γ-Fe2O3 nanosheets show similar adsorption behaviour for As(iii) and As(v)

As synthesised graphene-like, superparamagnetic γ-Fe2O3 nanosheets show superior inorganic arsenic scavenging performance, demonstrating the feasibility of solving an environmental problem through material innovation, and the foreground of 2D materials in environmental improvement.

Integrin-targeting with peptide-bioconjugated semiconductor-magnetic nanocrystalline heterostructures

Binary asymmetric nanocrystals (BNCs), composed of a photoactive TiO2 nanorod joined with a superparamagnetic γ-Fe2O3 spherical domain, were embedded in polyethylene glycol modified phospholipid micelle and successfully bioconjugated to a suitably designed peptide containing an RGD motif. BNCs represent a relevant multifunctional nanomaterial, owing to the coexistence of two distinct domains in one particle, characterized by high photoactivity and magnetic properties, that is particularly suited for use as a phototherapy and hyperthermia agent as well as a magnetic probe in biological imaging. We selected the RGD motif in order to target integrin expressed on activated endothelial cells and several types of cancer cells. The prepared RGD-peptide/BNC conjugates, comprehensively monitored by using complementary optical and structural techniques, demonstrated a high stability and uniform dispersibility in biological media. The cytotoxicity of the RGD-peptide/BNC conjugates was studied in vitro. The cellular uptake of RGD-peptide conjugates in the cells, assessed by means of two distinct approaches, namely confocal microscopy analysis and emission spectroscopy determination in cell lysates, displayed selectivity of the RGD-peptide-BNC conjugate for the αvβ3 integrin. These RGD-peptide-BNC conjugates have a high potential for theranostic treatment of cancer.

Monodisperse water-soluble -Fe2O3/polyvinylpyrrolidone nanoparticles for a magnetic resonance imaging contrast agent

Water-soluble γ-Fe2O3/polyvinylpyrrolidone (PVP) nanoparticles were obtained by transferring oleic acid (OA) coated iron-oxide nanocrystals from hexane to water. The particle size of the γ-Fe2O3/PVP nanoparticles with excellent monodispersity is about 14 nm. Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) results indicate that PVP anchors on the γ-Fe2O3 nanoparticles through its carbonyl group and provided sufficient hydrophilicity. The maghemite content in the γ-Fe2O3/PVP nanoparticles was about 81 wt-%. The saturation magnetisation of the superparamagnetic γ-Fe2O3/PVP nanoparticles is 57·7 emu g− 1 at 295 K. For in vivo magnetic resonance imaging (MRI) studies, the γ-Fe2O3/PVP nanoparticles can be guided to the target area by a permanent magnet and show negative contrast enhancement on the target area of laboratory mice.

Core-shell bifunctional catalyst for steam methane reforming resistant to H2S: Activity and structure evolution

Results of studies on the activity of the Ni-containing catalyst in the steam reforming of methane (SRM) process are presented. It is established that the catalyst shows high activity in SRM, stability to coke formation and resistance to H2S presence in the reaction gas mixture. The catalyst was prepared on the basis of mixed oxides separated from layered vermiculite. The structure and the phase composition of catalytically active components were investigated by XAFS, XRD, EDX, TEM and Moessbauer spectroscopy. It is found that the active components of catalyst are represented by clusters with core-shell configuration where FeNi alloy is a core (∼10 nm) surrounded by superparamagnetic γ-Fe2O3 shell (1–4 nm). These clusters are distributed in the mixed spinel Mg(Fe,Al)2O4 matrix. It is suggested that clusters of FeNi alloy are active in SRM while superparamagnetic γ-Fe2O3 particles are active in the oxidative decomposition of H2S.

Controlled assembly of magnetic nanoparticles on microbubbles for multimodal imaging

Magnetic microbubbles (MMBs) consisting of microbubbles (MBs) and magnetic nanoparticles (MNPs) were synthesized for use as novel markers for improving multifunctional biomedical imaging. The MMBs were fabricated by assembling MNPs in different concentrations on the surfaces of MBs. The relationships between the structure, magnetic properties, stability of the MMBs, and their use in magnetic resonance/ultrasound (MR/US) dual imaging applications were determined. The MNPs used were NPs of 3-aminopropyltriethoxysilane (APTS)-functionalized superparamagnetic iron oxide γ-Fe2O3 (SPIO). SPIO was assembled on the surfaces of polymer MBs using a "surface-coating" approach. An analysis of the underlying mechanism showed that the synergistic effects of covalent coupling, electrostatic adsorption, and aggregation of the MNPs allowed them to be unevenly assembled in large amounts on the surfaces of the MBs. With an increase in the MNP loading amount, the magnetic properties of the MMBs improved significantly; in this way, the shell structure and mechanical properties of the MMBs could be modified. For surface densities ranging from 2.45 × 10(-7) μg per MMB to 8.45 × 10(-7) μg per MMB, in vitro MR/US imaging experiments showed that, with an increase in the number of MNPs on the surfaces of the MBs, the MMBs exhibited better T2 MR imaging contrast, as well as an increase in the US contrast for longer durations. In vivo experiments also showed that, by optimizing the structure of the MMBs, enhanced MR/US dual-modality image signals could be obtained for mouse tumors. Therefore, by adjusting the shell composition of MBs through the assembly of MNPs in different concentrations, MMBs with good magnetic and acoustic properties for MR/US dual-modality imaging contrast agents could be obtained.