Magnetic Properties Of Nanoparticles Research Articles

Magnetic properties of exchanged-coupled nanostructured core–shell particles of CoO@MnFe[formula omitted]O[formula omitted

In this work the structural and magnetic properties of nanoparticles of bimagnetic core–shell CoO@MnFe2O4 were reported. The structure and the morphology of the nanoparticles were characterized by X-ray powder diffraction and by transmission electron microscopy. Hysteresis loops were recorded by varying the applied magnetic field (H) in the range ± 85 kOe for several temperature values (T). The T-dependence of the zero-field- and the field-cooling magnetization were investigated from room temperature until 5 K for H = 100 Oe. The coercivity was found to be enhanced to about 2.34 kOe at 5 K while shiftings in the hysteresis loops due to the exchange-bias effect were also observed reaching 472 Oe at 5 K. The blocking temperature for this core–shell nanoparticle system was also found to be ≈ 103 K. The enhancement in the coercivity and the exchange-bias effect are discussed within a model based on the exchange-coupling of the magnetic moments at the core–shell interface.

Unveiling the Role of the Properties of Magnetic Nanoparticles for Highly Efficient Low-Frequency Magneto-Mechanical Actuation of Biomolecules.

The role of the properties of magnetic nanoparticles in the remote magneto-mechanical actuation of biomolecules under the influence of external magnetic fields is still of particular interest. Here, a specially designed strategy based on the mechanical destruction of short oligonucleotide duplexes is used to demonstrate the effect of magnetic nanoparticles with different sizes (5-99 nm) on the magnitude of the magneto-mechanical actuations in a low-frequency alternating magnetic field. The results show that the mechanical destruction of complementary chains of duplexes, caused by the rotational-vibrational movements of nanoparticles upon exposure to a magnetic field, has a nonmonotonic dependence on the nanoparticle core size. The main hypothesis of this phenomenon is associated with a key role of magneto-dipole interactions between individual nanoparticles, which blocks the movements of nanoparticles in dense clusters. This result will allow fine-tuning of the magnetic nanoparticle properties for addressing specific magneto-mechanical tasks.

Magnetic Nanoparticles: A Review on Synthesis, Characterization, Functionalization, and Biomedical Applications.

Nowadays, magnetic nanoparticles (MNPs)are applied in numerous fields, especially in biomedical applications. Since biofluidic samples and biological tissues are nonmagnetic, negligible background signals can interfere with the magnetic signals from MNPs in magnetic biosensing and imaging applications. In addition, the MNPs can be remotely controlled by magnetic fields, which make it possible for magnetic separation and targeted drug delivery. Furthermore, due to the unique dynamic magnetizations of MNPs when subjected to alternating magnetic fields, MNPs are also proposed as a key tool in cancer treatment, an example is magnetic hyperthermia therapy. Due to their distinct surface chemistry, good biocompatibility, and inducible magnetic moments, the material and morphological structure design of MNPs has attracted enormous interest from a variety of scientific domains. Herein, a thorough review of the chemical synthesis strategies of MNPs, the methodologies to modify the MNPs surface for better biocompatibility, the physicochemical characterization techniques for MNPs, as well as some representative applications of MNPs in disease diagnosis and treatment are provided. Further portions of the review go into the diagnostic and therapeutic uses of composite MNPs with core/shell structures as well as a deeper analysis of MNP properties to learn about potential biomedical applications.

Role of lattice defects on the magnetism of gold nanoparticles irradiated with neutrons

The origin of the unexpected magnetic properties of nanoparticles made of gold, silver, or other diamagnetic metals remains obscure despite a large body of experimental and theoretical studies. Whereas many studies have endeavoured at finding correlations between magnetism and nanoparticle size or ligand coating, none so far has attempted at investigating the role of core crystallinity. We have irradiated gold nanoparticles with energetic neutrons or protons with the aim of nucleating lattice defects in the crystalline cores. Comparison of the magnetic behaviours before and after irradiation demonstrates clearly that the presence of defects in the crystalline lattice of the nanoparticles cores contributes efficiently to their magnetism.

Magnetic Manganese‐Based Micromotors MnFe2O4@Fe3O4/graphite and Mn2O3@Fe2O3@Fe3O4/graphite for Organic Pollutant Degradation

AbstractWastewater pollution with organic compounds poses a serious threat to human health. One of the possible methods for solving these problems can be the use of micro/nanomotors. Among them, manganese‐based micro/nanomotors have a number of important advantages related to high catalytic activity, powerful motion, and low cost. Due to their mobility, micro/nanomotors promote an increase in the intensity of mass transfer in the reacting system. When introducing ferromagnetic elements into manganese‐based micro/nanomotors, it is possible not only to increase their motion speed, but also to make their motion more controllable. Herein, for the first time it demonstrates a synthesis method for MnFe2O4@Fe3O4/graphite and Mn2O3@Fe2O3@Fe3O4/graphite magnetic catalytic micromotors, which have remarkable photocatalytic properties. Micromotors are clusters of nanoparticles whose motion in a hydrogen peroxide solution in a non‐uniform magnetic field is caused by the action of magnetic force and self‐diffusiophoresis. Nanoparticles are synthesized by the plasma‐arc method with subsequent annealing in the air. When changing the annealing temperature, the catalytic and magnetic properties of nanoparticles can vary within a wide range of values. Micromotors MnFe2O4@Fe3O4/graphite have the most optimal catalytic and magnetic properties. The results of the research show that these micromotors are effective catalysts in the decomposition of methylene blue.

Green Synthesis of Magnetic Nanoparticles from Oldenlandia diffusa: Characterization and Therapeutic Activities

This study investigated green synthesis of magnetic nanoparticles (MNP) using Oldenlandia diffusa, its cauterization, and therapeutic propertieson liver cancer cells via an in-vitro approach. Anti-cancer, anti-oxidant, and anti-diabetic properties of MNP were evaluated. Synthesis of MNP was confirmed via UV-visible spectroscopy. Oldenlandia diffusa MNP (20–40 nm) showed absorption peak at 327 nm in UV-visible, XRD, EDX and FTIR spectral analysis. MNP were monoclinic, and rhombohedral with two stretching peaks at 646 cm−1, and 1098 cm−1 confirming Fe–O–Fe mode and Fe = O due to the iron element. IC50 values for MNP (IC50 74 μg/ml & 58 μg/ml) using DPPH and ABTS methods were high as compared to aqueous leaf extract of Oldenlandia diffusa confirming anti-oxidant properties. MNP exhibited α-amylase inhibitory activity with maximum inhibition of 82.17±0.82 μg/ml for α-glucosidase inhibitory action of 84.82±0.89 μg/ml. MNP showed dose-dependant in-vitro tumor suppression activity against HepG2 cells (16.08% at 150 μg/ml and 28.31% at 150 μg/ml). MNP also demonstrated anti-leishmanial activity at 400 g/ml (74.26±0.82 g/ml for promastigotes and 69.40±0.69 μg/ml for amastigotes). Oldenlandia diffusa actively bonded with magnetic Fe-nanoparticles and suppressed the growth of HepG2 cells. It demonstrated anti-cancer, antioxidant, anti-leishmanaland anti-diabetic activities. Thus, Oldenlandia diffusa is a potential anti-cancer therapeutic drug for liver cancer.

Aggregation of Magnetic Nanoparticles in Biological Solvents Evaluated by HTS-SQUID Magnetic Immunoassay System

Magnetic nanoparticles (MNPs) have been studied for various medical applications by taking advantage of their unique magnetic properties. Magnetic immunoassay (MIA) is a technique for the rapid detection of target biomarkers by antigen-antibody reaction between antibody-modified MNPs and the target biomarker. In this study, we aim to improve the accuracy of the MIA, we evaluated the AC magnetic properties of MNPs in the biological solvents. To measure the magnetic signal of MNPs, we used the developed HTS-SQUID magnetic immunoassay system. First, we evaluated the instability of the HTS-SQUID magnetic immunoassay system using pellets of manganese (II) fluoride. The results show that the device instability due to operating time does not affect the measurement of magnetic signal changes in MNPs due to biological solvents. Since the magnetic properties of MNPs depend on particle size and viscosity, we measured the time evolution of the magnetic signal of Resovist in glycerin, human serum, sheep whole blood, and NaCl. It was found that the magnetic signal of Resovist decreased exponentially with ions contained in the solvent. The results are fitted as the exponential double function, suggesting that the magnetic signal of MNPs in biological solvents is affected by the aggregation of MNPs in the blood and that there are at least two steps in the mechanism of the aggregation.

Ferromagnetic Resonance in Magnetic Oxide Nanoparticules: A Short Review of Theory and Experiment

This review article aims to provide a comprehensive overview of recent FMR studies on magnetic oxide nanoparticles and their potential applications. The use of the FMR technique is a powerful tool to study the magnetic properties of magnetic nanoparticles and can provide valuable information on their behavior. For this, we will start by discussing the purpose of these magnetic nanoparticles and their application in various fields, including biomedical applications, energy storage, and environmental remediation. We will then discuss the methods used to prepare magnetic nanoparticles and the theory behind FMR including the superparamagnetic effect. Additionally, we will present the most recent studies on FMR for magnetic oxide nanoparticles by highlighting the effect of temperature and doping on the magnetic properties of these nanoparticles.

Phase Composition and Magnetic Properties of Nanoparticles with Magnetite–Maghemite Structure

Precipitation of nanopowders with mixed magnetite–maghemite composition was carried out under different conditions and with different separation techniques. The exact character of interactions of different iron oxide phases in the nanopowder was the main object of interest. The obtained nanopowders have spherical particles about 10–20 nm in size. Electron paramagnetic resonance (EPR) study showed that iron ions incorporate fully into magnetite and maghemite structures. The shape of the EPR line points out that single homogenous solid solutions were formed during synthesis. In the studied solid solutions, different ratios of vacancies and Fe2+/Fe3+ ratios were observed but in spite of different synthesis techniques in both cases, there were no additional diamagnetic structural phases presented.

Impact of colloidal stabilization of MnZn-ferrite nanoparticles by oleic acid on their magnetothermal properties

Introduction: The development of magnetic agents for magnetic fluid hyperthermia application is a complex task requiring simultaneous optimization of chemical, biomedical, magnetic, and, in particular, thermal properties of magnetic nanoparticles (MNPs). In the majority of papers, the magnetothermal measurements are carried out on bare MNPs suspended in deionized water with subsequent optimization of the required physiological and medical properties, including toxicity and biocompatibility. However, in real hyperthermia practice, the stable fluids or colloids of magnetic MNPs are used, and the colloidal stabilization can significantly modify their magnetic properties, including magnetothermal ones.Methods: This paper is focused on the study of ZnxMn1-xFe2O4 MNPs stabilized by oleic acid/sodium oleate in this context.Results and Discussion: Our research demonstrates the crucial changes in the magnetic properties and magnetothermal response of ZnMn ferrite MNPs after the colloidal stabilization: while bare MNPs demonstrate significant coercivity, nonzero remanent magnetization, and superquadratic dependence of heat generation on the magnetic field amplitude, the magnetic properties of colloidal ZnMn ferrite MNPs are typical for superparamagnetic ones and their magnetothermal response is described by a conventional quadratic dependence on magnetic field amplitude. Various factors such as size distribution, magnetic anisotropy, and interparticle dipole–dipole interaction are considered as the origins of such an impact on magnetic MNPs’ properties.

Magnetic Nanoparticle-Based High-Performance Positive and Negative Magnetic Resonance Imaging Contrast Agents.

In recent decades, magnetic nanoparticles (MNPs) have attracted considerable research interest as versatile substances for various biomedical applications, particularly as contrast agents in magnetic resonance imaging (MRI). Depending on their composition and particle size, most MNPs are either paramagnetic or superparamagnetic. The unique, advanced magnetic properties of MNPs, such as appreciable paramagnetic or strong superparamagnetic moments at room temperature, along with their large surface area, easy surface functionalization, and the ability to offer stronger contrast enhancements in MRI, make them superior to molecular MRI contrast agents. As a result, MNPs are promising candidates for various diagnostic and therapeutic applications. They can function as either positive (T1) or negative (T2) MRI contrast agents, producing brighter or darker MR images, respectively. In addition, they can function as dual-modal T1 and T2 MRI contrast agents, producing either brighter or darker MR images, depending on the operational mode. It is essential that the MNPs are grafted with hydrophilic and biocompatible ligands to maintain their nontoxicity and colloidal stability in aqueous media. The colloidal stability of MNPs is critical in order to achieve a high-performance MRI function. Most of the MNP-based MRI contrast agents reported in the literature are still in the developmental stage. With continuous progress being made in the detailed scientific research on them, their use in clinical settings may be realized in the future. In this study, we present an overview of the recent developments in the various types of MNP-based MRI contrast agents and their in vivo applications.

Dimension-Dependent Magnetic Behavior of Manganese-Cysteine Inorganic Complex Nanoparticles.

A cysteine-based complex of Mn2+ led to the formation of nanoparticles in aqueous medium under ambient conditions. The formation and evolution of the nanoparticles in the medium were followed by ultraviolet-visible light (UV-vis) spectroscopy, circular dichroism, and electron spin resonance spectroscopy that also revealed a first-order process. The magnetic properties of the nanoparticles isolated as solid powders exhibited strong crystallite and particle size dependence. At low crystallite size, as well as particle size, the complex nanoparticles showed superparamagnetic behavior similar to other magnetic inorganic nanoparticles. The magnetic nanoparticles were found to undergo a superparamagnetic to ferromagnetic transition, and then to paramagnetic transition with a gradual increase in either their crystallite size or particle size. The discovery of dimension-dependent magnetic property of inorganic complex nanoparticles may usher in a superior option for tuning the magnetic behavior of nanocrystals, depending on the component ligands and metal ions.

Green synthesis of iron oxide nanoparticles using Hibiscus plant extract

In the present work, hematite (α-Fe2O3) nanoparticles (NPs) were synthesized by using a simple and facile green synthesis by using Hibiscus plant extract. The used solution is composed of plant extract and 0.1 M of iron chloride mixture. The nanoparticles are grown at ambient temperature. The prepared nanoparticles morphology, structure and composition were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission microscopy (HRTEM). The synthesized nanoparticles are formed by agglomeration of spherical and mono-disperse grains. XRD analysis reveals that the grains are polycrystalline with an average particle size of 20 nm. The calcinated nanoparticles contain small traces of maghemite and hydroxide. A vibrating sample magnetometer (VSM) was used for the nanoparticle magnetic properties determination. The finding reveals the superparamagnetic behaviour of the synthesized α-Fe2O3 nanoparticles owing to a saturated magnetization (Ms) of 0.96 emu/g, and low remnant magnetization Mr of 0.06 emu/g.

Tuning the magnetic properties of oleic-acid-coated cobalt ferrite nanoparticles by varying the surfactant coverage

Organic coatings on magnetic nanoparticles are extensively used in various applications. As demonstrated recently, these coatings affect the magnetic behavior of the nanoparticles. The modification of the magnetic properties of the nanoparticles and nanoparticle assemblies as the percentage of the oleic acid (OA) coverage of a cobalt ferrite nanoparticle increases, is investigated numerically using a multiscale modeling approach that combines density functional theory (DFT) and Monte Carlo simulations. The DFT calculations show that the increase in OA coverage results in a monotonic decrease of the mean magneto-crystalline anisotropy and in a reduction of the atomic magnetic moments and the exchange coupling constants in the nanoparticle. These effects are attributed to the gradual recovery of the bulk spinel structure at the coated surface, as the OA coverage increases. Input from the DFT calculations is used in the mesoscopic modeling for the study of the magnetic behavior of an assembly of these nanoparticles by employing the Monte Carlo simulations technique. The results demonstrate that despite the decrease of magnetic anisotropy, the coercive field increases with the increase in percentage of OA coverage in the assembly, in agreement with experimental findings. This study suggests the possibility of tailoring the magnetic properties of cobalt ferrite nanoparticles for high-performance applications by varying the organic coating concentration.

Reaction time-induced improvement in hyperthermia properties of cobalt ferrite nanoparticles with different sizes

Chemical reaction conditions involved in the formation of nanoscale materials can enormously affect their properties. However, the correlation between the reaction time (RT) and hyperthermia properties of magnetic nanoparticles (MNPs) is yet to be understood. Here, we synthesize cobalt ferrite magnetic nanoparticles (MNPs) using a thermal decomposition technique with different RT values. The variation in RT (70–180 min) is designed in such a way that the nucleation and growth process can be affected and improved considerably, achieving monodisperse spherical-like MNPs with superparamagnetic nature as confirmed by first-order reversal curve analysis. Hyperthermia properties are studied for cobalt ferrite MNP ferrofluids with different concentrations (1–5 mg/ml) at various magnetic field strengths (100–400 Oe). We obtain a maximum specific loss power (SLP) value of 510 W/g for MNPs synthesized using RT = 150 min. By extracting magnetic characteristic, we find a correlation between SLP and coercive field values as a function of RT, which can shed light on subtle changes in hyperthermia properties of MNPs.

A prediction model for magnetic particle imaging–based magnetic hyperthermia applied to a brain tumor model

Background and objectiveBrain tumor is a global health concern at the moment. Thus far, the only treatments available are radiotherapy and chemotherapy, which have several drawbacks such as low survival rates and low treatment efficacy due to obstruction of the blood-brain barrier. Magnetic hyperthermia (MH) using magnetic nanoparticles (MNPs) is a promising non-invasive approach that has the potential for tumor treatment in deep tissues. Due to the limitations of the current drug-targeting systems, only a small proportion of the injected MNPs can be delivered to the desired area and the rest are distributed throughout the body. Thus, the application of conventional MH can lead to damage to healthy tissues. MethodsMagnetic particle imaging (MPI)-guided treatment platform for MH is an emerging approach that can be used for spatial localization of MH to arbitrarily selected regions by using the MPI magnetic field gradient. Although the feasibility of this method has been demonstrated experimentally, a multidimensional prediction model, which is of crucial importance for treatment planning, has not yet been developed. Hence, in this study, the time dependent magnetization equation derived by Martsenyuk, Raikher, and Shliomis (which is a macroscopic equation of motion derived from the Fokker-Planck equation for particles with Brownian relaxation mechanism) and the bio-heat equations have been used to develop and investigate a three-dimensional model that predicts specific loss power (SLP), its spatio-thermal resolution (temperature distribution), and the fraction of damage in brain tumors. ResultsBased on the simulation results, the spatio-thermal resolution in focused heating depends, in a complex manner, on several parameters ranging from MNPs properties to magnetic fields characteristics, and coils configuration. However, to achieve a high performance in focused heating, the direction and the relative amplitude of the AC magnetic heating field with respect to the magnetic field gradient are among the most important parameters that need to be optimized. The temperature distribution and fraction of the damage in a simple brain model bearing a tumor were also obtained. ConclusionsThe complexity in the relationship between the MNPs properties and fields parameter imposes a trade-off between the heating efficiency of MNPs and the accuracy (resolution) of the focused heating. Therefore, the system configuration and field parameters should be chosen carefully for each specific treatment scenario. In future, the results of the model are expected to lead to the development of an MPI-guided MH treatment platform for brain tumor therapy. However, for more accurate quantitative results in such a platform, a magnetization dynamics model that takes into account coupled Néel-Brownian relaxation mechanism in the MNPs should be developed.

Controlled Release of Doxorubicin from Magnetoliposomes Assisted by Low-Frequency Magnetic Field.

The article presents magnetoliposomes as potential carriers of doxorubicin. The magnetic properties of nanoparticles embedded in liposomes enable the targeting of drug-loaded carriers to cancer cells and subsequent release of their payload using an external alternating magnetic field as a trigger. The cytotoxicity of empty and doxorubicin-loaded magnetoliposomes in the absence and after exposure to magnetic field was evaluated in cancerous and normal breast cells. The characteristic shows the carrier with size distribution <130 nm, slightly negative zeta potential and polydispersity index <0.2. Doxorubicin was encapsulated in magnetoliposomes with an efficiency of 31 % and released in the presence of an alternating magnetic field at 50 %. Magnetoliposomes with drug provided high cytotoxic effect on tumor cells and low cytotoxic effect on normal cells. The research conducted in this article may indicate the potential application of the studied magnetoliposomes in release of drugs under the influence of magnetic field in cancer cells.

Temperature influence on NiFeMo nanoparticles magnetic properties and their viability in biomedical applications.

NiFeMo alloy nanoparticles were synthesized by co-precipitation in the presence of organic additives. Nanoparticles thermal evolution shows that there is a significant increase in the average size (from 28 to 60 nm), consolidating a crystalline structure of the same type as the Ni3 Fe phase but with lattice parameter a=0.362 nm. Measurements of magnetic properties follow this morphological and structural evolution increasing saturation magnetization (Ms) by 578% and reducing remanence magnetization (Mr) by 29%. Cell viability assays on as-synthesized revealed that nanoparticles (NPs) are not cytotoxic up to a concentration of 0.4μg/mL for both non-tumorigenic (fibroblasts and macrophages) and tumor cells (melanoma).

Formulation and Characterization of Fe3O4@PEG Nanoparticles Loaded Sorafenib; Molecular Studies and Evaluation of Cytotoxicity in Liver Cancer Cell Lines.

Iron oxide nanoparticles are one of the nanocarriers that are suitable for novel drug delivery systems due to low toxicity, biocompatibility, loading capacity, and controlled drug delivery to cancer cells. The purpose of the present study is the synthesis of coated iron oxide nanoparticles for the delivery of sorafenib (SFB) and its effects on cancer cells. In this study, Fe3O4 nanoparticles were synthesized by the co-precipitation method, and then sorafenib was loaded onto PEG@Fe3O4 nanoparticles. FTIR was used to ensure polyethylene glycol (PEG) binding to nanoparticles and loading the drug onto the nanoshells. A comparison of the mean size and the crystalline structure of nanoparticles was performed by TEM, DLS, and X-ray diffraction patterns. Then, cell viability was obtained by the MTT assay for 3T3 and HepG2 cell lines. According to FT-IR results, the presence of O-H and C-H bands at 3427 cm-1 and 1420 cm-1 peak correlate with PEG binding to nanoparticles. XRD pattern showed the cubic spinel structure of trapped magnetite nanoparticles carrying medium. The magnetic properties of nanoparticles were examined by a vibrating-sample magnetometer (VSM). IC50 values at 72 h for treatment with carriers of Fe3O4@PEG nanoparticle for the HepG2 cell line was 15.78 μg/mL (p < 0.05). This study showed that Fe3O4 nanoparticles coated by polyethylene glycol and using them in the drug delivery process could be beneficial for increasing the effect of sorafenib on cancer cells.

Preparation and Characterization of Magnetic Iron Oxide (Fe3 O4 ) Nanoparticles with Different Polymer Coating Agents

In the present study, the influence of the organic stabilizers on the formation of magnetic iron-oxide nanoparticles was investigated. Polyethylene glycol (PEG), dextran (DEX), and chitosan was chosen as biocompatible surface modification agents for obtained magnetic nanoparticles. The structure of the coated Fe3 O4 nanoparticles was learned by the X-ray diffraction and Fouriertransform infrared spectroscopic methods. It was explored that the PEG coated magnetic nanoparticles have relatively larger crystallite sizes, which indicate a more ordered crystal structure of these nanoparticles. Furthermore, FT-IR analysis showed that the Fe3 O4 -PEG system possesses a stronger nanoparticle-stabilizer interaction at the supramolecular level. This study emphasizes the significance of optimizing the surface properties of magnetic nanoparticles when using them in biomedical applications.