Effects Of Fe3O4 Research Articles

Anti-microbial, anti-biofilm, and efflux pump inhibitory effects of ellagic acid-bonded magnetic nanoparticles against Escherichia coli isolates.

The spread of microbial resistance is a threat to public health. In this study, the anti-microbial, anti-biofilm, and efflux pump inhibitory effects of ellagic acid-loaded magnetic nanoparticles (Fe3O4NPs@EA) against beta-lactamase producing Escherichia coli isolates have been investigated. The effects of Fe3O4 NPs@EA on the growth inhibition of E. coli isolates were determined by disc diffusion method and determining the minimum inhibitory concentration was done using broth micro-dilution method. The anti-biofilm effect of nanoparticles was investigated using the microplate method. The efflux pump inhibitory effect of nanoparticles was investigated using cart-wheel method and by investigating the effect of nanoparticles on acrB and tolC genes expression levels. Fe3O4 NPs@EA showed anti-bacterial effects against test bacteria, and the MIC of these nanoparticles varied from 0.19 to 1.56 mg/mL. These nanoparticles caused a 43-62% reduction in biofilm formation of test bacteria compared to control. Furthermore, efflux pump inhibitory effect of these nanoparticles was confirmed at a concentration of 1/8 MIC, and the expression of acrB and tolC genes decreased in bacteria treated with 1/4 MIC Fe3O4 NPs@EA. According to the results, the use of nanoparticles containing ellagic acid can provide a basis for the development of new treatments against drug-resistant E. coli. This substance may improve the concentration of antibiotics in the bacterial cell and increase their effectiveness by inhibiting the efflux in E. coli isolates.

Microstructure and magnetic properties of the FeSiBCuNb nanocrystalline soft magnetic composites coated with oil-phase single Fe3O4 nanoparticles by thermal decomposition method

Here, the core-shell structured FeSiBCuNb/Fe3O4 soft magnetic composites (SMCs) were successfully designed and fabricated by coating Fe3O4 magnetic nanoparticles on the surface of phosphorylated FeSiBCuNb powder. The effects of Fe3O4 and Polyvinylpyrrolidone (PVP) contents on the micromorphology, interface structure, and soft magnetic properties of SMCs were systematically investigated. The results demonstrate that the Fe3O4 magnetic nanoparticles are uniformly distributed on the surface of magnetic powders, which fill up the air gap in-between the magnetic powder and increase the resistivity. It shows that the permeability gradually decreases with the increase of Fe3O4 from 0 wt% to 1 wt%, while the loss decreases first and then increases. The loss separation of SMCs indicates that the Fe3O4 nanoparticles effectively reduce the hysteresis loss and eddy current loss. Furthermore, the FeSiBCuNb/Fe3O4 SMCs with the addition of PVP as a binder enhance the binding force between Fe3O4 nanoparticles and the powder matrix, which facilitates the formation of a uniform and dense interface structure. When adding 0.3 wt% PVP + Fe3O4 nanoparticles, the FeSiBCuNb/Fe3O4 SMCs exhibit excellent soft magnetic properties with ultra-low loss of 138.5 kW/m3 (100 mT/50 kHz), high permeability of 54, and good frequency stability. The presented results provide a new strategy for synthesizing ultra-low core loss and frequency stability of core-shell structured SMCs, which has great potential for applications at high frequencies.

Preparation of mixed-mode weak cation exchange magnetic solid-phase extraction sorbent and its application in the extraction of 21 illicit drugs from wastewater

The detection of illicit drugs in wastewater can effectively monitor and evaluate the trend of illicit drug abuse. A novel mixed-mode cation exchange magnetic sorbent Fe3O4 @poly(ST/DVB/MA-COOH) was prepared and firstly applied as magnetically dispersed solid phase extraction material to efficiently, rapidly, and selectively extract 21 illicit drugs from wastewater. The selectivity of the sorbent was mainly attributed to the electrostatic interaction. The effects of Fe3O4 @poly(ST/DVB/MA-COOH) preparation and extraction conditions on the adsorption performance were thoroughly discussed. Among the 21 illicit drugs, the absolute extraction recovery values for 19 illicit drugs were greater than 80 % and the entire adsorption process could be achieved in one minute. Subsequently, the Fe3O4 @poly(ST/DVB/MA-COOH) sorbent combined with UHPLC-MS/MS was used to establish a quantitative method for the effectively extracted 19 illicit drugs in wastewater. The method had a good determination coefficient in the range of 0.2–200 ng/L and the limits of detection of the method were 0.03–0.67 ng/L. The spiked recovery values were in the range of 87.0–119.6 %. Finally, the method was successfully applied to the detection of 19 illicit drugs in wastewater samples and also compared with the commonly used SPE method. The obtained results indicate that Fe3O4 @poly(ST/DVB/MA-COOH) has great advantages in the detection of illicit drugs in wastewater.

Exosomes from magnetic particles-primed mesenchymal stem cells enhance neural differentiation of PC12 cells

This study aimed to investigate the effects of mesenchymal stem cell exosomes loaded with Fe3O4 magnetic particles (Fe3O4@ MSC-exo) on the survival and neural differentiation of PC12 cells. Exosomes were separated from Fe3O4 magnetic nanoparticles-primed umbilical cord mesenchymal stem cells condition medium by ultracentrifugation and characterized by transmission electron microscopy, flow nano analysis, and western blotting. PC12 cells were treated with culture medium containing exosomes. The effects of Fe3O4@ MSC-exo on PC12 cell proliferation, migration, and neural differentiation were analyzed using CCK-8 assay, transwell migration assay, RT-qPCR, and immunofluorescence, respectively. Additionally, miRNA sequencing was performed on Fe3O4@ MSC-exo, followed by bioinformatic analysis of the results. We found that Fe3O4@ MSC-exo can promote PC12 cell proliferation, migration, and neural differentiation. According to the sequencing results, there were a total of 43 differentially expressed miRNAs. The present study indicated that Fe3O4@ MSC-exo might enhance nerve cell function, laying the foundation for targeted therapy of nerve injury.

Comparative physiological and metabolomic analyses reveal that Fe3O4 and ZnO nanoparticles alleviate Cd toxicity in tobacco

BackgroundHeavy metals repress tobacco growth and quality, and engineered nanomaterials have been used for sustainable agriculture. However, the underlying mechanism of nanoparticle-mediated cadmium (Cd) toxicity in tobacco remains elusive.ResultsHerein, we investigated the effects of Fe3O4 and ZnO nanoparticles (NPs) on Cd stress in tobacco cultivar ‘Yunyan 87’ (Nicotianatabacum). Cd severely repressed tobacco growth, whereas foliar spraying with Fe3O4 and ZnO NPs promoted plant growth, as indicated by enhancing plant height, root length, shoot and root fresh weight under Cd toxicity. Moreover, Fe3O4 and ZnO NPs increased, including Zn, K and Mn contents, in the roots and/or leaves and facilitated seedling growth under Cd stress. Metabolomics analysis showed that 150 and 76 metabolites were differentially accumulated in roots and leaves under Cd stress, respectively. These metabolites were significantly enriched in the biosynthesis of amino acids, nicotinate and nicotinamide metabolism, arginine and proline metabolism, and flavone and flavonol biosynthesis. Interestingly, Fe3O4 and ZnO NPs restored 50% and 47% in the roots, while they restored 70% and 63% in the leaves to normal levels, thereby facilitating plant growth. Correlation analysis further indicated that these metabolites, including proline, 6-hydroxynicotinic acid, farrerol and quercetin-3-O-sophoroside, were significantly correlated with plant growth.ConclusionsThese results collectively indicate that metal nanoparticles can serve as plant growth regulators and provide insights into using them for improving crops in heavy metal-contaminated areas.Graphical

Effects of Fe₃O₄ on the denitrification performance of Pseudomonas stutzeri

Biological denitrification is the most widely used technology for nitrate removal in wastewater treatment. Conventional denitrification requires long hydraulic retention time, and the nitrate removal efficiency in winter is low due to the low temperature. Therefore, it is expected to develop new approaches to enhance the denitrification process. In this paper, the effect of adding different concentrations of Fe₃O₄ nanoparticles on the denitrification catalyzed by Pseudomonas stutzeri was investigated. The maximum specific degradation rate of nitrate nitrogen improved from 18.0 h⁻¹ to 23.7 h⁻¹ when the concentration of Fe₃O₄ increased from 0 mg/L to 4 000 mg/L. Total proteins and intracellular iron content also increased along with increasing the concentration of Fe₃O₄. RT-qPCR and label-free proteomics analyses showed that the relative expression level of denitrifying genes napA, narJ, nirB, norR, nosZ of P. stutzeri increased by 55.7%, 24.9%, 24.5%, 36.5%, 120% upon addition of Fe₃O₄, and that of denitrifying reductase Nap, Nar, Nir, Nor, Nos increased by 85.0%, 147%, 16.5%, 47.1%, 95.9%, respectively. No significant difference was observed on the relative expression level of denitrifying genes and denitrifying reductases between the bacteria suspended and the bacteria adhered to Fe₃O₄. Interestingly, the relative expression level of electron transfer proteins of bacteria adhered to Fe₃O₄ was higher than that of the bacteria suspended. The results indicated that Fe₃O₄ promoted cell growth and metabolism through direct contact with bacteria, thereby improving the denitrification. These findings may provide theoretical support for the development of enhanced denitrification.

Triclosan removal by heterogeneous Fenton-like process: Studying the kinetics and surface chemistry of Fe3O4 as catalyst

Fe3O4 was used as a recoverable catalyst in heterogeneous Fenton-like process for Triclosan (TCS) degradation in this study. The kinetics and surface chemistry of the catalyst were investigated in detail. Peroxymonosulfate (PMS) was used to generate radicals and found to be an effective oxidant used with Fe3O4. The effects of Fe3O4 and PMS dosage, adsorption, pH and catalyst surface charges were studied. The system is at optimum at [TCS:PMS] at 1:25 and increases linearly with Fe3O4 dosage from 0.125 to 0.750 g/L. Under the optimum condition, TCS was removed in less than 60 min. It is concluded that Fe3O4 has the role of both adsorbent and catalyst. TCS and PMS are adsorbed near or onto Fe3O4 surface for catalytic reactions. The pH level has a critical effect on the reaction as it changes the form of active sites of Fe3O4. The active site of Fe3O4 is positive ( Fe−OH2+) in acidic and negative ( Fe–O−) in alkaline solution, leading to different adsorbility of PMS and TCS. The optimum pH for this reaction is in pH 6–9, in which the low surface charges on Fe3O4 allow both PMS and TCS to access active sites and form inner-sphere complex for reaction.

Laminar forced convection performance of non-Newtonian water-CNT/Fe3O4 nano-fluid inside a minichannel hairpin heat exchanger: Effect of inlet temperature

This numerical study aims to focus on the effect of difference between the inlet temperatures of working fluids on the hydrothermal characteristics of a counter-current minichannel hairpin heat exchanger. The water flows in the annulus side and the water based hybrid nano-fluid containing Fe3O4 and carbon nanotubes (CNTs) passes through the tube side of heat exchanger. Temperature-dependent thermal conductivity and viscosity are considered for the non-Newtonian hybrid nano-fluid. The effects of Fe3O4 and CNT volume fractions as well as the Reynolds number on the performance metrics of the heat exchanger are also assessed. The results revealed that the increase of difference between the inlet temperatures of working fluids leads to the augmentation of heat transfer rate, overall heat transfer coefficient (except at Reynolds number of 500), heat exchanger effectiveness and PEC; while the pumping power diminishes with the increase of inlet water temperature.

Preparation and properties of polyimide/Fe3O4 composite foams

Purpose This paper aims to develope the electromagnetic interference shielding materials with high performance. To develop advanced polymer-based electromagnetic interference shielding materials with rather high temperature stability, good processability and moderate mechanical properties, the authors chose the polyimide (PI) foam as matrix and ferriferrous oxide (Fe3O4) as fillers to prepare the composite foams with lightweight and rather good electromagnetic interference shielding performance. Design/methodology/approach Some polyimide nanocomposite foams with Fe3O4 as fillers have been prepared by in situ dispersion and foaming with pyromellitic dianhydride (PMDA) and isocyanate (PAPI) as raw materials and water as foaming agent. By varying the Fe3O4 contents, a series of PI/Fe3O4 nanocomposite foams with fine microstructures and high thermal stability were obtained. The structure and performances of nanocomposite foams were examined, and the effects of Fe3O4 on the microstructure and properties of composite foams were investigated. Findings This work demonstrates that PI/Fe3O4 foams could be fabricated by thermally treating the polyimide foam intermediates with Fe3O4 nanoparticles through a blending reaction of precursors. The final PI/Fe3O4 composite foams maintained the excellent thermal property and showed a super paramagnetic behaviour, which has a positive effect on the improvement of electromagnetic shielding performance. Research limitations/implications In this paper, the effects of Fe3O4 on the performances of PI/Fe3O4 composite foam were reported. It provided an effective methodology for the preparation of polymer/Fe3O4 nanocomposite foams, which hold great promise towards the potential application in the areas of electromagnetic shielding materials. Originality/value A series of PI/Fe3O4 composite foams with different contents of Fe3O4 were prepared by blending reaction of the precursors. The effects of Fe3O4 on the structures and properties of PI/Fe3O4 composite foam were discussed in detail.

Preparation and characterization of CaO–Al2O3–SiO2 glass-ceramics from molybdenum tailings

Molybdenum tailings (MTs) are by-products of the molybdenum mining industry, and further treatment are necessary before their disposal for avoiding contamination of the environment, such as landfills, plant covers, or using material productions. Here, MTs were blended with other chemical raw materials to manufacture a decorative glass-ceramic of CaO–Al2O3–SiO2 by sintering processes. The effects of Fe3O4 and TiO2 oxides in MTs on the melting and crystallization behavior of the glasses were investigated by DSC, XRD, FESEM, FTIR, and TEM. The results showed that the crystallization temperature (Tc) and crystallization activation energy (E) of the glasses decreased when the amount of MTs increased from 41 to 49 wt% (M1-M5). Wollastonite (CaSiO3) and catena-silicate (Ca2.87Fe0.13(SiO3)3), which constituted as the major and minor crystalline phases, were precipitated in the prepared glass-ceramic. In the five specimens tested, the crystalline phases were evenly distributed throughout the surface and sufficiently interlocked together. This one step sintering process, in which the glass ceramic was nucleated and crystallized at 1110 °C for 2 h, generated a material with an appearance suitable for building decoration.

Assessing the Impact of Iron-based Nanoparticles on pH, Dissolved Organic Carbon, and Nutrient Availability in Soils

With the ongoing commercialization of nanotechnology products, the increasing use of engineered nanoparticles (NPs) could lead potentially to environmental risks. This study investigated the dynamic influences of three iron-based NPs (Fe0, Fe3O4, and Fe2O3) applied into a red soil (RS) and a Wushan soil (WS) with different application rates (2 to 6 g kg−1) on soil physicochemical properties such as pH, dissolved organic carbon (DOC), available ammonium nitrogen (NH4 +-N), available phosphorus (AP), and enzymatic activities. The results showed that the addition of Fe0 NPs increased DOC and available NH4 +-N, but significantly decreased AP, while Fe3O4 and Fe2O3 NPs slightly reduced soil pH in both soils and significantly declined available NH4 +-N in the WS and AP in the RS. No significant difference was observed between the effects of Fe3O4 and Fe2O3 NPs on soil properties except AP in the RS. All iron-based NPs decreased the activities of urease and acid phosphatase in both soils. The effects on soil physicochemical properties, especially available NH4 +-N and AP induced by iron-based NPs, varied greatly with soil types. These results implied that cautions should be paid for the environmental application of iron-based NPs, especially iron oxide NPs in soils.

Effect of nanoscale Fe3O4, TiO2 and carbon particles on cucumber seed germination

The effects of Fe3O4, TiO2 and carbon nanoparticles on the cucumber (Cucumis sativus) seed germination rate, root elongation and germination index were studied. The nanoparticles used ranged in average particle size from 30–50 nm, and their concentration ranged from 0 to 5000 μg/mL. Inhibitory effects were observed and the reduction in root growth was more obvious than the seed germination percentages. In all cases some perturbations of the normal functions with respect to control in germinating test were observed. The results obtained provide a better understanding of the phytotoxicity of the nanomaterials used in this study, and may help to further understand the interaction of nanoparticles with the environment prior to their use in agriculture.

Hybrid nanocomposites based on superparamagnetic and ferromagnetic particles: A comparison of their magnetic and dielectric properties

Nanocomposites of magnetic nanoparticles and polymer matrices combine the properties of their components, and as such are good examples of functional nanomaterials with excellent application potential. Against this background, experimental and theoretical studies of such composites are of great interest. In this study we aim to provide insight into the static and dynamic magnetic response, as well as the dielectric response, of magnetic nanocomposites subjected to external magnetic and electric fields. We directly compare the behavior of polyurethane films doped with superparamagnetic Fe3O4, and blocked ferromagnetic CoFe2O4 nanoparticles. While a reversible, Langevin magnetization curve is observed for Fe3O4@PU films, hysteretic magnetic behavior is found in case of CoFe2O4@PU films. The hysteresis observed for CoFe2O4 nanoparticles can be explained by interactions at the interface between particles and polymer matrix in conjunction with its ferromagnetic nature. The results of dielectric spectroscopy experiments revealed different effects of Fe3O4 and CoFe2O4 nanoparticles on polymer dynamics.

Fabrication and Thermoelectric Properties of p-Type Bi<sub>1</sub>Sb<sub>4</sub>Te<sub>7.5</sub> Alloy Doped with Fe<sub>3</sub>O<sub>4</sub>

We investigated the effects of Fe3O4 (0~0.1 wt.%) on the thermoelectric properties of Bi1Sb4Te7.5 alloy prepared by mechanical alloying process. The Seebeck coefficient increased with Fe3O4 content, but the power factor decreased with Fe3O4 content because of the decreased electrical conductivity. The thermal conductivity decreased with Fe3O4. The carrier concentration measured by the Hall effect measurement decreased with Fe3O4. The thermal conductivity of 0.1 wt.% Fe3O4 alloy was 0.814 W/Km, 20%lower than that of Fe3O4 free alloy. As a result, the small addition of Fe3O4 improved the Z value owing to the decreased thermal conductivity by adding Fe3O4. The Z value of 0.01 wt.% Bi1Sb4Te7.5 alloy was 3.1×10-3 /K, the highest value among the prepared alloys.