The combination of magnetic hyperthermia therapy with the controlled release of chemotherapeutic agents in tumors may be an efficient therapeutic with few side effects because the bioavailability, ...tolerance and amount of the drug can be optimized. Here, we prepared magnetoliposomes consisting of magnetite nanoparticle cores and the anticancer drug gemcitabine encapsulated by a phospholipid bilayer. The potential of these magnetoliposomes for controlled drug release and cancer treatment via hyperthermic behavior was investigated. The magnetic nanoparticle encapsulation efficiency was dependent on the initial amount of magnetite nanoparticles present at the encapsulation stage; the best formulation was 66%. We chose this formulation to characterize the physicochemical properties of the magnetoliposomes and to encapsulate gemcitabine. The mean particle size and distribution were determined by dynamic light scattering (DLS), and the zeta potential was measured. The magnetoliposome formulations all had acceptable characteristics for systemic administration, with a mean size of approximately 150 nm and a polydispersity index <0.2. The magnetoliposomes were stable in aqueous suspension for at least one week, as determined by DLS. Temperature increases due to the dissipation energy of magnetoliposome suspensions subjected to an applied alternating magnetic field (AMF) were measured at different magnetic field intensities, and the values were appropriated for cancer treatments. The drug release profile at 37 °C showed that 17% of the gemcitabine was released after 72 h. Drug release from magnetoliposomes exposed to an AMF for 5 min reached 70%.
Magnetic fluids, more specifically aqueous colloidal suspensions containing certain magnetic nanoparticles (MNPs), have recently been gaining special interest due to their potential use in clinical ...treatments of cancerous formations in mammalians. The technological application arises mainly from their hyperthermic behavior, which means that the nanoparticles dissipate heat upon being exposed to an alternating magnetic field (AMF). If the temperature is raised to slightly above 43 °C, cancer cells are functionally inactivated or killed; however, normal cells tend to survive under those same conditions, entirely maintaining their bioactivity. Recent in vitro studies have revealed that under simultaneous exposure to an AMF and magnetic nanoparticles, certain lines of cancer cells are bio-inactivated even without experiencing a significant temperature increase. This non-thermal effect is cell specific, indicating that MNPs, under alternating magnetic fields, may effectively kill cancer cells under conditions that were previously thought to be implausible, considering that the temperature does not increase more than 5 °C, which is also true in cases for which the concentration of MNPs is too low. To experimentally test for this effect, this study focused on the feasibility of inducing K562 cell death using an AMF and aqueous suspensions containing very low concentrations of MNPs. The assay was designed for a ferrofluid containing magnetite nanoparticles, which were obtained through the co-precipitation method and were functionalized with citric acid; the particles had an average diameter of 10 ± 2 nm and a mean hydrodynamic diameter of approximately 40 nm. Experiments were first performed to test for the ability of the ferrofluid to release heat under an AMF. The results show that for concentrations ranging from 2.5 to 1.0 × 10
3
mg L
−1
, the maximum temperature increase was actually less than 2 °C. However, the in vitro test results from K562 cells and suspensions containing these MNPs at concentrations varying within a narrower range from 2.5 to 10 mg L
−1
, typically under an AMF of 15 kA m
−1
at 356 kHz, indicate efficient cytotoxic activity against malignant cells and inhibition of cell growth, even at very low hyperthermally induced temperature increases. The IC
50
value varied with time, reaching 3.5 mg L
−1
after 10 min under the AMF. Our results effectively demonstrate new prospective uses for such nanoparticles in advanced medical practices in oncology.
Graphical Abstract
In the present work, the reactivity of a heterogeneous Fenton system based on thermally treated goethite, particularly focusing on the effect of surface Fe
2+ sites on the iron oxide particles to ...degrade quinoline in aqueous medium was studied. The reactions were monitored by using an electrospray ion source with an Agilent ion trap mass spectrometer (ESI-MS). The chemical mechanism was modeled with theoretical calculations.
▪
A heterogeneous Fenton-like reaction occurring on the thermally modified surface of a synthetic iron oxide previously treated with a H
2 stream was investigated. The quinoline decomposition, used as an organic substrate model, was monitored with electrospray ionization mass spectrometry. Quinoline was found to be oxidized through a successive hydroxylation mechanism. These results strongly suggest that highly reactive hydroxyl radicals, generated during the reaction involving H
2O
2 on the catalysts surface, respond for this oxidation, and confirm that the material is an efficient heterogeneous Fenton-like catalyst. Theoretical quantum mechanics calculations, by the density functional theory (DFT), were carried out in order to understand the basic molecular degradation steps for quinoline decomposition mechanism on this H
2-treated goethite (αFeOOH) surface.
Nanoparticles of magnetite (Fe3O4) were obtained by reacting ferric chloride with sodium sulphite, through the reduction-precipitation method. The effects of adding tetramethylammonium hydroxide ...(TMAOH) during or after the precipitation of the iron oxide were studied in an attempt to obtain well-dispersed magnetite nanoparticles. Accordingly, the following experimental conditions were tested: (i) precipitation in absence of TMAOH (sample Mt), (ii) the same as (i) after peptizing with TMAOH (Mt1), (iii) TMAOH added to the reaction mixture during the precipitation of magnetite (Mt2). Analyses with transmission electron microscopy (TEM), X-ray diffraction, Mössbauer spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), zeta potential, and magnetization measurements up to 2.5 T revealed that magnetite was normally formed also in the medium containing TMAOH. The degree of particles agglomeration was monitored with laser diffraction and technique and inspection of TEM images. The relative contributions of Néel and Brownian relaxations on the magnetic heat dissipation were studied by investigating the ability of suspensions of these magnetite nanoparticles to release heat in aqueous and in hydrogel media. Based on ATR-FTIR and zeta potential data, it is suggested that the surfaces of the synthesized magnetite particles treated with TMAOH become coated with (CH3)4N+ cations.
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► Reuse of industrial steel waste as a catalyst for wastewater treatment. ► Use of a low-cost catalyst as an iron source for photo-Fenton-like processes. ► High activity of steel ...waste for the decolorization of RR195 by AOPs. ► Evidence of homogeneous and heterogeneous photo-Fenton reactions with steel waste as the catalyst.
This study investigated the use of blast furnace dust (BFD) as a catalyst to degrade an azo dye (RR195) by photo-Fenton-like processes. This waste contains hematite, magnetite and maghemite as iron sources, and its dissolution provides more Fe3+ than Fe2+ for the Fenton reaction in solution. The effect of hydrogen peroxide concentration and catalyst dosage on the kinetics of hydrogen peroxide decomposition and dye decolorization was also studied. The photo-Fenton-like process was compared to Fenton-like (using BDF without irradiation), Fenton and photo-Fenton (using FeSO4 as iron source), UV/H2O2 and UV processes. The results indicated that BFD can be effectively used as a catalyst in the photocatalytic process because it was able to completely degrade H2O2 via an adjusted Langmuir–Hinshelwood model. Although the photo-Fenton-like reaction with BFD showed the same decolorization efficiency of RR195 as the homogeneous photo-Fenton process (using FeSO4), the catalyst considerably increased the reaction rates (more than five times) according pseudo-first-order kinetics. The results of the irradiated systems using BFD can be more efficient in dye decolorization due to greater hydroxyl radical production through Fe2+/Fe3+ cycling and by the occurrence of homogeneous and heterogeneous reactions. The practical use of the steel waste is promising, because it increases the reaction rates and its high density and magnetic proprieties enable an easy solid–liquid separation and reuse, making it a versatile material for environmental applications.
Samples of ferrofluids containing chemically stabilized nanoparticles of magnetite (Fe3O4) with tetramethylammonium hydroxide (TMAOH) were prepared by a direct reduction–precipitation method. The ...influences of aging time and temperature on the size and monodispersion characteristics of the produced nanoparticles were investigated. Transmission electron microscopy, powder X-ray diffraction, Fourier-transform infrared, and magnetization measurements with applied magnetic field up to 2T were used to characterize the synthesized iron oxides. Raising the temperature of the synthesized material in autoclave affects positively the monodispersion of the nanoparticles, but it was not found to significantly influence the size itself of individual particles.
► From report protocols, chemical synthesis of magnetite with FeCl3 (stable in air) instead of FeCl2 or Fe(NO3)3, precursor. ► Chemical reduction with Na2SO3 provides an additional advantage. ► As any eventual reformation of Fe3+ from reoxidization of produced Fe2+ may be sequestered by remaining SO32− in the medium. ► Nanoparticles are stably individualized with tetramethylammonium hydroxide that acts as a surface-active agent. ► Thermal treatment reduces further the mean sizes of particles, as required for many medical uses.
In this work the adsorption features of activated carbon and the magnetic properties of iron oxides were combined in a composite to produce magnetic adsorbents. These magnetic particles can be used ...as adsorbent for a wide range of contaminants in water and can subsequently be removed from the medium by a simple magnetic procedure. Activated carbon/iron oxide magnetic composites were prepared with weight ratios of 2:1, 1.5:1 and 1:1 and characterized by powder XRD, TG, magnetization measurements, chemical analyses, TPR, N
2 adsorption–desorption isotherms, Mössbauer spectroscopy and SEM. The results suggest that the main magnetic phase present is maghemite (γ-Fe
2O
3) with small amounts of magnetite (Fe
3O
4). Magnetization enhancement can be produced by treatment with H
2 at 600 °C to reduce maghemite to magnetite. N
2 adsorption measurements showed that the presence of iron oxides did not significantly affect the surface area or the pore structure of the activated carbon. The adsorption isotherms of volatile organic compounds such as chloroform, phenol, chlorobenzene and drimaren red dye from aqueous solution onto the composites also showed that the presence of iron oxide did not affect the adsorption capacity of the activated carbon.
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▶ A simple method for the liquid-phase aerobic oxidation of thiols has been developed. ▶ Co–Fe inexpensive magnetic materials are used as efficient heterogeneous catalysts. ▶ ...Disulfides can be obtained in high yields at low catalyst loading (0.008mol%). ▶ The catalyst does not undergo leaching and can be recovered magnetically and reused. ▶ The reaction occurs under mild alkali free conditions using air as an oxygen source.
Cobalt–iron magnetic composites prepared by the thermal treatment of an iron oxide-rich soil in the presence of sucrose and cobalt(II) sulfate are efficient heterogeneous catalysts for the liquid-phase aerobic oxidation of thiols into disulfides. The materials have been characterized by Mössbauer spectroscopy, XRD, N2 adsorption–desorption, and elemental analysis. It has been shown that the isomorphic substitution of iron by cobalt occurs preferentially in the framework of the wüstite (FeO) phase and strongly affects the catalytic behavior of the material. The choice of a solvent is critically important for the efficiency of the reaction. In weakly basic solvents, such as dimethylformamide and dimethylacetamide, disulfides can be obtained in near-quantitative yields at low catalyst loading (0.008mol%). A significant practical advantage of this environment-friendly process is the use of inexpensive magnetically recoverable materials as catalysts and oxygen as a final oxidant as well as mild alkali free conditions. Of particular note are the stability of the catalyst toward leaching and the possibility of catalyst recycling without any special treatment.
In this work, the adsorption features of clays with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as ...adsorbent for contaminants in water and can be subsequently removed from the medium by a simple magnetic process. The bentonite–iron oxide magnetic composites have been prepared with weight ratios of 2:1, 1.5:1, and 1:1 and characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TG), magnetization measurements, chemical analyses, temperature-programmed reduction (TPR), N
2 adsorption–desorption isotherms, Mössbauer spectroscopy, and scanning electron microscopy (SEM). The results suggest that the main magnetic phase present is maghemite (γ-Fe
2O
3). A magnetization enhancement can be produced by treatment with H
2 at 600 °C to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m
2 g
−1 (
V
micropores=0.003 cm
3 g
−1) for the pure bentonite to 55 m
2 g
−1 (
V
micropores=0.009 cm
3 g
−1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni
2+, Cu
2+, Cd
2+, and Zn
2+ from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite.
Zinc hexacyanoferrate (ZnHCF) is a Prussian Blue analog and can be intercalated by both monovalent and divalent ions. ZnHCF/multi-walled carbon nanotube (MWCNT) film could be used as a cathode for ...zinc ions battery. Carbon nanotubes improved significantly the electrochemical performance of the electrode. It is described the preparation of ZnHCF/MWCNT films by the interfacial method with cyclohexane/water mixture as solvent. The crystal structure, morphology, and microstructure of the as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, Mossbaüer, Raman spectroscopy, and infrared spectroscopy. Results revealed that the MWCNTs extend the electrochemical properties of the ZnHCF and influence the structure and morphology of the hexacyanoferrate particles. If tested as cathode material for zinc ion batteries, the nanocomposite film exhibits a capacity of 25.81 mA h g-1, which is much higher than those obtained for a ZnHCF single-component film (3.28 mA h g-1). The physical characteristics and properties that allow good reversibility to a high potential difference, achieved with the ZnHCF/MWCNT film, suggest new developments in the manufacture of translucent, flexible and light energy storage devices, which can be used as a lower-cost, safer and environmentally friendly alternative to the currently existing technologies.
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