Dispersed Iron Oxide Nanoparticles Research Articles

SBA-15 with short-sized channels modified with Fe2O3 nanoparticles. A novel approximation of an efficient adsorbent for As removal in contaminated water

AbstractThe urgent need for technologies to ensure health standards, as per the Sustainable Development Goals established by the United Nations, has prompted research into addressing human health problems associated with chemical contaminants in air, water, and soil. Heavy metals, particularly arsenic, pose significant health risks, with millions of people worldwide exposed to concentrations exceeding recommended limits. Nanostructured materials, including ordered mesoporous substrates such as SBA-15, have shown promise for arsenic removal due to their high surface area and pore characteristics. This study aimed to synthesize a silica mesoporous material with reduced pore channel length to enhance surface area and active sites, thereby improving arsenic removal efficiency. By exploring various surfactant-to-silica precursor ratios, a suitable value was identified to promote the production of shortened SBA-15 particles. These shortened pore channels facilitated the dispersion of iron oxide nanoparticles (Fe2O3) on the SBA-15 surface, resulting in an effective adsorbent that achieved over 95% arsenic removal. The combination of the modified SBA-15 substrate and Fe2O3 nanoparticles demonstrated high efficiency in arsenic removal from aqueous effluents, offering a promising solution to address water pollution and associated health risks.

Magnetic-Responsive Liposomal Hydrogel Membranes for Controlled Release of Small Bioactive Molecules-An Insight into the Release Kinetics.

This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were prepared by encapsulation of 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) multilayered vesicles (MLVs) loaded with ferulic acid (FA), i.e., DPPC:FA liposomes, into gelatin hydrogel membranes containing dispersed iron oxide nanoparticles (MNPs), i.e., magnetic-responsive gelatin. The FA release mechanisms and kinetics from magnetic-responsive liposomal gelatin were studied and compared with those obtained with conventional drug delivery systems, e.g., free liposomal suspensions and hydrogel matrices, to access the effect of liposome entrapment and magnetic field on FA delivery. FA release from liposomal gelatin membranes was well described by the Korsmeyer-Peppas model, indicating that FA release occurred under a controlled diffusional regime, with or without magnetic stimulation. DPPC:FA liposomal gelatin systems provided smoother controlled FA release, relative to that obtained with the liposome suspensions and with the hydrogel platforms, suggesting the promising application of liposomal hydrogel systems in longer-term therapeutics. The magnetic field, with low intensity (0.08 T), was found to stimulate the FA release from magnetic-responsive liposomal gelatin systems, increasing the release rates while shifting the FA release to a quasi-Fickian mechanism. The magnetic-responsive liposomal hydrogels developed in this work offer the possibility to magnetically activate drug release from these liposomal platforms based on a non-thermal related delivery strategy, paving the way for the development of novel and more efficient applications of MLVs and liposomal delivery systems in biomedicine.

Ethanol-water motifs-A re-interpretation of the double-difference pair distribution functions of aqueous iron oxide nanoparticle dispersions.

In dispersion, nanoparticles can interact with the surrounding dispersion medium, such that an interfacial region with a structure differing from that of the bulk exists. Distinct nanoparticulate surfaces induce specific degrees of interfacial phenomena, and the availability of surface atoms is a crucial prerequisite for interfacial restructuring. Here, we investigate the nanoparticle-water interface of 0.5-10 wt. % aqueous iron oxide nanoparticle dispersions of 6nm diameter in the presence of 6 vol. % ethanol with x-ray absorption spectroscopy (XAS) and atomic pair distribution function (PDF) analysis. The absence of surface hydroxyl-groups in XAS spectra is in accordance with the double-difference PDF (dd-PDF) analysis, due to a fully covered surface from the capping agent. The previously observed dd-PDF signal is not stemming from a hydration shell, as postulated in Thomä et al. [Nat Commun. 10, 995 (2019)], but from the residual traces of ethanol from nanoparticle purification. With this article, we provide an insight into the arrangement of EtOH solutes in water at low concentration.

Magnetic heating of water dispersible and size-controlled superparamagnetic cobalt iron oxide nanoparticles

Magnetic nanoparticles have been of great interest for various biomedical applications due to their controllability in the distance. Monodisperse superparamagnetic CoFe2O4 (CFO) nanoparticles were synthesized by solvothermal method with oleic acid. The oleic acid ligands are exchanged with citric acid to obtain water-dispersible citric acid-coated CA (CFO–CA) nanoparticles. The M–H curve recorded at room temperature shows the superparamagnetic nature of CFO nanoparticles for both oleic- and citric-coated samples. The magnetic heating performance of CFO–CA shows an exciting dependence on the particle size and surface functionality. The hyperthermia efficiency of CFO–CA nanoparticles increases with increasing magnetic field strength and nanoparticle concentration. A specific absorption ratio value of 152.7 W/g obtained in this study is comparable to other investigations, demonstrating a great potential of CFO–CA nanoparticles for hyperthermia-based treatments. This controlled synthesis process can be applied to various functional biomedical nanoparticles to prepare nanoparticles with designed surface moieties for further potential applications.

A novel formulation of active hexagonal‐compact nano packed composite system using emerging technology for food packaging applications

AbstractWe report the nanoformulation of the active hexagonal‐compact nano‐packed composite system with iron oxide nanoparticles and glossy glutinous chitosan‐tapioca starch biopolymer solution (CTS‐S) for improved potential benefit in food packaging applications. The high pressure processing (HPP) treatment at various pressure level ranging from 100 to 500 MPa at constant time 120 s and optimized the formation of hexagonal nano‐packed system at 500 MPa. The UV–vis spectrophotometer (UV), Fourier transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD) and Zeta potential analysis suggested uniform dispersion of iron oxide nanoparticles and formulated an effective stable nano‐packed composite structure. The XRD analysis of HPP treated sample confirmed the enhancement in material properties with high degree of crystallinity nature. Further studies on antimicrobial effects for HPP treated nano‐packed composite solution exhibited an excellent antimicrobial property and examined over a period of 1 month against microbial deterioration. The study revealed that the novel nano‐packed composite solution could be used as an antimicrobial food packaging material.Practical applicationThe research focused to the development of novel formulation of active hexagonal nano‐packed composite system using non‐thermal high pressure pascalization (HPP) technology. For the first time the design of compact nano structural pattern from the composite solution was developed which expresses an anti‐microbial characteristic even after exposed to environmental condition for a month. The experimental results revealed the practical application of formulated nano‐packed composite system with improvement bio‐physical properties and material characteristics has created an interest toward the food‐borne microbial barrier coating material which can be used in food packaging applications as well as promoting longer shelf life of food products with fabrication of nano‐packaging material as a commercial beneficial aspect in food packaging industries.

Beam-induced redox chemistry in iron oxide nanoparticle dispersions at ESRF-EBS.

The storage ring upgrade of the European Synchrotron Radiation Facility makes ESRF-EBS the most brilliant high-energy fourth-generation light source, enabling in situ studies with unprecedented time resolution. While radiation damage is commonly associated with degradation of organic matter such as ionic liquids or polymers in the synchrotron beam, this study clearly shows that highly brilliant X-ray beams readily induce structural changes and beam damage in inorganic matter, too. Here, the reduction of Fe3+ to Fe2+ in iron oxide nanoparticles by radicals in the brilliant ESRF-EBS beam, not observed before the upgrade, is reported. Radicals are created due to radiolysis of an EtOH-H2O mixture with low EtOH concentration (∼6 vol%). In light of extended irradiation times during insitu experiments in, for example, battery and catalysis research, beam-induced redox chemistry needs to be understood for proper interpretation of insitu data.

Microwave-Enabled Size Control of Iron Oxide Nanoparticles on Reduced Graphene Oxide

Nanoparticle-functionalized 2D material networks are promising for a wide range of applications, but in situ formation of nanoparticles is commonly challenged by rapid growth. Here, we demonstrate controlled synthesis of small and dispersed iron oxide nanoparticles on reduced graphene oxide (rGO) networks through rapid localized heating with microwaves with low-cost iron nitrate as the precursor. The strong coupling of the microwave radiation with the rGO network rapidly heats the network locally to decompose the iron nitrate and generate iron oxide nanoparticles, while cessation of microwaves leads to rapid cooling to minimize crystal growth. Small changes in the microwave reaction time (<1 min) led to very large changes in the iron oxide morphology. The solid-state microwave syntheses produced narrower nanoparticle size distribution than conventional heating. These results illustrate the potential of solid-state microwave syntheses to control the nanoparticle size on 2D materials through rapid localized heating under the microwave process conditions, which should be extendable to a variety of transition metal oxide-rGO systems.

Design of concentrated colloidal dispersions of iron oxide nanoparticles in ionic liquids: Structure and thermal stability from 25 to 200 °C

HypothesisSome of the most promising fields of application of ionic liquid-based colloids imply elevated temperatures. Their careful design and analysis is therefore essential. We assume that tuning the structure of the nanoparticle-ionic liquid interface through its composition can ensure colloidal stability for a wide temperature range, from room temperature up to 200 °C. ExperimentsThe system under study consists of iron oxide nanoparticles (NPs) dispersed in ethylmethylimidazolium bistriflimide (EMIM TFSI). The key parameters of the solid-liquid interface, tuned at room temperature, are the surface charge density and the nature of the counterions. The thermal stability of these nanoparticle dispersions is then analysed on the short and long term up to 200 °C. A multiscale analysis is performed combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA). FindingsFollowing the proposed approach with a careful choice of the species at the solid-liquid interface, ionic liquid-based colloidal dispersions of iron oxide NPs in EMIM TFSI stable over years at room temperature can be obtained, also stable at least over days up to 200 °C and NPs concentrations up to 12 vol% (≈30 wt%) thanks to few near-surface ionic layers.

Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration.

The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide nanoparticles with phase-changing organic ligand shells agglomerate at temperatures between 5 °C and 20 °C. We observed the concurrent change in magnetic properties using magnetic particle spectroscopy (MPS) with a temporal resolution on the order of seconds and found reversible switching of magnetic properties of SPIONs by changing their agglomeration state. The non-linear correlation between magnetization amplitude from MPS and agglomeration degree from SAXS data indicated that the agglomerates' size distribution affected magnetic properties.

Effect of Iron Oxide Nanoparticles on the Physical Properties of Medium Density Fiberboard.

This paper investigates the influence of iron oxide (Fe2O3) nanoparticles on the physical properties of medium density fiberboard (MDF). In this study, three different nano iron oxide loadings, i.e., 0.5, 1.5 and 2.5 wt %, and untreated poplar fibers were used. The iron oxide (Fe2O3) nanoparticles were initially dispersed into urea formaldehyde resin using a high-vacuum mechanical stirrer before being incorporated into natural fibers. The untreated poplar fibers were wound onto metal frames to produce dry mat layers. Twenty different composite samples were made. All composite samples were tested for physical properties, i.e., thickness swelling, water absorption, moisture content and density in accordance with standards EN-317, ASTM D570, EN-322 and EN-323 respectively. Based on the results, it was found that the incorporation of homogeneously dispersed iron oxide nanoparticles significantly improved thickness swelling (Ts). Moreover, water absorption (WA) improved by up to 49.18 and 34.54%, respectively, at the highest loading of 2.5 wt %. Microstructure was investigated and characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) and we examined whether iron oxide nanoparticles exhibit good interactions with urea formaldehyde and poplar wood fibers. Heat and mass transfer investigation in the form of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) was carried out due to the impact of Fe2O3 nanoparticles. The curing temperature and thermal stability of the resin were enhanced due to the addition of Fe2O3 nanoparticles. A one-way ANOVA statistical analysis was established to effectively control the use of Fe2O3 nanoparticles. Therefore, the presence of iron oxide nanoparticles in an epoxy polymer contributes to a stiffer matrix that, effectively, enhances the capability of improving the physical properties of nano MDF.

Synthesis and Characterization of Water Dispersible Iron Oxide (�a-Fe2O3) Nanoparticles for Biomedical Applications

In this study, L-lysine coated �a-Fe2O3 nanoparticles were synthesized by a chemical approach in two steps. In the first step �a-Fe2O3 nanoparticles were synthesized by a polyol-reduction method. XRD analysis confirmed the presence of cubic maghemite phase with an average crystallite size of 9.2 nm. SEM analysis showed that the prepared �a-Fe2O3 nanoparticles have a spherical structural morphology with the tendency of agglomeration and with size in the range 8.36- 10.69 nm. The �a-Fe2O3 nanoparticles were coated with L-lysine in the second stage in an aqueous dispersion with ultrasonication followed by a gentle heating at 40��C. FT-IR spectroscopy confirmed the presence of L-lysine on the nanoparticles surface and the Zeta potential also supported the coating of nanoparticles with a hydrophilic layer of amino acid (L-lysine) and a good stability in aqueous medium. Hysteresis loop shows a ferromagnetic behavior at room temperature for both samples.

Enhancing arsenic adsorption via excellent dispersion of iron oxide nanoparticles inside poly(vinyl alcohol) nanofibers

Superparamagnetic iron oxide nanoparticles (SPIONs) are great adsorbents of toxic arsenic in water. However, SPIONs efficiency is limited by a tendency towards agglomeration, and an extra filtering process is required in actual applications to avoid possible harmful effects of nanoparticles released to the environment. Here, we show a novel green method to confine and disperse SPIONs (10 nm) inside insoluble electrospun PVA nanofibers (final concentration 0.14 wt. %). We found that the resulting membrane has an enhanced arsenic adsorption capacity (> 52 mg/g) and presents a new adsorption mechanism, involving a high swelling of the superhydrophilic nanofibers before actual solution interchange can occur. A suitable heat treatment provided water insolubility to the membrane while maintaining hydrophilicity and active sites in the SPIONs. We show the excellent dispersion and homogeneous distribution of the SPIONs inside the nanofibers using electron microscopies and scale this analysis to an area of statistical significance via magnetic studies and novel Small and Wide Angle X-Ray Scattering SAXS/WAXS 2D scannings. The production process is environmentally friendly, given that only PVA was used as SPIONs dispersant and no chemicals were added for crosslinking. This work presents a novel material that expands the broad technological applications of both iron oxide nanoparticles and electrospinning, opening a route to new horizons in water purification.

Effects of an oscillating magnetic field on ice nucleation in aqueous iron‐oxide nanoparticle dispersions during supercooling and preservation of beef as a food application

AbstractThis study was aimed to explore the effects of an oscillating magnetic field (OMF) on the ice nucleation behavior of distilled water (DW) and iron‐oxide nanoparticle dispersion (IND) during supercooling. The magnetic field intensity and distribution of the OMF produced by Helmholtz coils were predicted using COMSOL. It was hypothesized that the ferric nanoparticles in the IND would promote the heterogeneous ice nucleation, and the OMF could inhibit the nucleation process by rotating the particles. The supercooling probability of IND was significantly increased by 36% under the OMF at the ambient temperature of −10°C. However, the OMF also enhanced the supercooling stability of DW by 32%, suggesting that it could induce the dipolar movements of water molecules via water diamagnetism and create the induced electric fields, subsequently suppressing the occurrence of ice nucleation within DW as well. As an extended application, fresh beef was preserved in a supercooled state with the OMF treatment and its supercooled state was effectively extended for a week at the temperature of −4°C. The supercooling preservation potentially prolonged the shelf life of meat with no significant changes in drip loss, color, and bacterial growth for up to a week in this study.Practical applicationsRecently, the application of an oscillating magnetic field (OMF) has attracted considerable interest in the food preservation industry because the OMF is supposed to control ice nucleation during the freezing process. The present study demonstrated that the OMF treatment potentially suppressed ice nucleation in water and aqueous iron‐oxide nanoparticle dispersion. As a case study, beef steaks were preserved at subzero temperatures with the OMF treatment and they were successfully supercooled at −4°C for up to 7 days. The supercooling technology based on the OMF allowed to maintain the meat quality for an extended period while preventing bacterial growth. This novel technology can be integrated into a commercial refrigeration system and ensure the prolonged shelf life of various food products.

Synthesis and Characterization of Oleic Acid Coated Magnetic Nanoparticles for Hyperthermia Applications

In this study, we aimed to synthesize stable dispersions of iron oxide nanoparticles (IONs) coated with different amounts of oleic acid (OA) suitable for magnetic nano hyperthermia applications. For this purpose, bare and different amounts of oleic acid (0.2%, 0.5% and 1.0%, v/v) coated IONs were prepared by co-precipitation method. Then, their structures, morphologies, magnetic properties and heating abilities were characterized by using suitable techniques. IONs+1.0%OA nanoparticles showed low agglomeration with high dispersion capacity. Moreover, 1.0% OA coating showed the highest heating ability with a temperature increase of (25.2 °C) compared to IONs+OA (0.2%, 16.4 °C; 0.5%, 19 °C), but similar with bare IONs (26.7 °C). The specific absorption rate (SAR) values of bare IONs and IONs+OA (0.2%, 0.5%, 1.0% v/v) were found as 39.50, 34.81, 23.36 and 45.98 W/g, respectively. Our results showed that the comparable hyperthermia effect of IONs+1.0%OA with bare IONs was attributable to their uniform dispersion performance along with higher SAR values. We concluded that the dispersion of hydrophobic IONs+OA in an aqueous medium is one of the critical requirements for increasing temperature in magnetic nano hyperthermia applications.

Interfacial Behavior of Oligo(Ethylene Glycol) Dendrons Spread Alone and in Combination with a Phospholipid as Langmuir Monolayers at the Air/Water Interface.

Dendrons consisting of two phosphonate functions and three oligo(ethylene glycol) (OEG) chains grafted on a central phenoxyethylcarbamoylphenoxy group were synthesized and investigated as Langmuir monolayers at the surface of water. The OEG chain in the para position was grafted with a t-Bu end-group, a hydrocarbon chain, or a partially fluorinated chain. These dendrons are models of structurally related OEG dendrons that were found to significantly improve the stability of aqueous dispersions of iron oxide nanoparticles when grafted on their surface. Compression isotherms showed that all OEG dendrons formed liquid-expanded Langmuir monolayers at large molecular areas. Further compression led to a transition ascribed to the solubilization of the OEG chains in the aqueous phase. Brewster angle microscopy (BAM) provided evidence that the dendrons fitted with hydrocarbon chains formed liquid-expanded monolayers throughout compression, whilst those fitted with fluorinated end-groups formed crystalline-like domains, even at large molecular areas. Dimyristoylphosphatidylcholine and dendron molecules were partially miscible in monolayers. The deviations to ideality were larger for the dendrons fitted with a fluorocarbon end-group chain than for those fitted with a hydrocarbon chain. Brewster angle microscopy and atomic force microscopy supported the view that the dendrons were ejected from the phospholipid monolayer during the OEG conformational transition and formed crystalline domains on the surface of the monolayer.

Electro-optic switching and memory effect in suspension of ferroelectric liquid crystal and iron oxide nanoparticles

In this work, impact of dispersion of iron oxide nanoparticles (Fe2O3 NPs) into ferroelectric liquid crystal (FLC) SCE-13 mixture on the electro-optical and dielectric properties has been studied. It has been found that the dispersion of Fe2O3 NPs in host FLC matrix exhibits pronounced influence on response time, spontaneous polarization, rotational viscosity and voltage required for switching the FLC molecules. Also dispersed system shows memory effect as confirmed by the optical texture and dielectric permittivity studies. Effort has been made to explain the experimental results as for as possible.

Effect of Polymer Surface Modification of Superparamagnetic Iron Oxide Nanoparticle Dispersions in High Salinity Environments

Superparamagnetic nanoparticles (SPIONs) can be used as nuclear magnetic resonance (NMR) signal enhancement agents for petroleum exploration. This enhancement effect is uniform if SPIONs are monodisperse in size and in composition; yet it is challenging to synthesize monodisperse particles that do not aggregate in high salinity petroleum brine. Here, we report a method to synthesize individual SPIONs coated with tunable surface coating densities of poly(2-acrylamido-2-methyl-1-propanesulfonic acid (pAMPS) with a catechol end-group (pAMPS*). To establish parameters under which pAMPS*-coated SPIONS do not aggregate, we compared computational predictions with experimental results for variations in pAMPS* chain length and surface coverage. Using this combined theoretical and experimental approach, we show that singly dispersed SPIONs remained stabilized in petroleum brine for up to 75 h with high surface density pAMPS*.

Atomic insight into hydration shells around facetted nanoparticles

Nanoparticles in solution interact with their surroundings via hydration shells. Although the structure of these shells is used to explain nanoscopic properties, experimental structural insight is still missing. Here we show how to access the hydration shell structures around colloidal nanoparticles in scattering experiments. For this, we synthesize variably functionalized magnetic iron oxide nanoparticle dispersions. Irrespective of the capping agent, we identify three distinct interatomic distances within 2.5 Å from the particle surface which belong to dissociatively and molecularly adsorbed water molecules, based on theoretical predictions. A weaker restructured hydration shell extends up to 15 Å. Our results show that the crystal structure dictates the hydration shell structure. Surprisingly, facets of 7 and 15 nm particles behave like planar surfaces. These findings bridge the large gap between spectroscopic studies on hydrogen bond networks and theoretical advances in solvation science.

Particle assembling induced by non-homogeneous magnetic field at transformer oil-based ferrofluid/silicon crystal interface by neutron reflectometry

The effect of magnetic nanoparticle assembly formation at a planar interface between a transformer oil-based ferrofluid and single-crystal silicon under non-homogeneous magnetic fields was studied by specular neutron reflectometry. The ferrofluid probed represents a stable suspension of dispersed iron oxide nanoparticles (characteristic size about 10 nm) coated with oleic acid in a low-polarity liquid carrier (transformer oil). It was shown that the reflectivity curves are sensitive to the application of a non-homogeneous external magnetic field. In particular, at a low magnetic flux density (<35 mT) they are well described in terms of the simplest model of a strict boundary between two semi-infinite homogeneous media. Nevertheless, slight concentrating of the ferrofluid bulk at the interface was detected. At a high magnetic flux density (35–75 mT), the analysis gives a three-layered structure of in-depth profiles of the scattering length density, thus showing the formation of two effective adsorption layers with different content of magnetic nanoparticles in them.

Electrochemical study of magnetic nanogel designed for controlled release of chlorhexidine gluconate

Intensive care is required for patient with higher degree of burns as they are prone to sepsis mortality. Topical antimicrobials/antiseptics are the conventional treatment of choice with each having its limitation in terms of toxicity and effectiveness. Magnetic nanogel have long been studied for in vivo drug delivery in cancer treatment. Inspired by fact that incorporation of magnetic nanoparticles will enhance the antimicrobial properties of nanogel, we developed a chitosan-gelatin based polymer with dispersed magnetic Cobalt iron oxide nanoparticles for controlled release of chlorhexidine gluconate. MNPs were synthesized by co-precipitation method and confirmation of CoFe2O4 phase was done with XRD analysis. Nanogel was fabricated by solution casting method and further characterization to determine drug interaction with polymer and MNPs was performed using Fourier Transformed Infra-Red Spectroscopy, Scanning Electron Microscopy, and Electroanalytical methods including Cyclic Voltammetry, Square Wave Voltammetry and Electrochemical Impedance Spectroscopy. Results of the study indicate that electrochemical nature of nanogel is pH dependent and the drug release can be induced at pH ranging from 6 to 7. Findings of this study highlight potential of the synthesized nanogel in developing burn care treatment that enables on demand drug release in response to sepsis with changing pH and can be integrated with detection system due to the presence of MNPs in it.