Concentration Of Magnetic Nanoparticles Research Articles

Dual solutions on MHD radiative three-dimensional bidirectional nanofluid flow over a non-linearly permeable shrinking sheet

The bidirectional flow and thermal transfer of magnetohydrodynamics (MHD) and radiative nanofluid (magnetite-vacuum pump oil) due to a nonlinear shrinking surface in a three dimensional system is studied. The boundary layer model is first transformed into a set of ordinary differential equations using the similarity transformations, and then solved using the bvp4c solver. The accuracy of the present model is justified by comparing present data with the numerical values from the published findings. The effect of factors (magnetic parameter, radiation parameter and nanoparticles volumetric concentration) on the development of responses (skin friction coefficient and thermal rate) and critical value (separation value from laminar to turbulent flow) is observed through the graphical presentation. In addition, two solutions are attained where the first solution is affirmed as the reliable solution through stability analysis. Conclusively, the suction effect is necessary in generating the solutions under the phenomenon of opposing shrinking flow. The addition of magnetic parameter and nanoparticles concentration can enhance both responses as well as the critical value while the radiation parameter tends to reduce the heat transfer coefficient. The types of stretching/shrinking velocity (linear/nonlinear) also affect the heat transfer rate. The critical value can be extended by using the linear velocity, but, for thermal enhancement, the nonlinear form of velocity can significantly develop the thermal rate better than the linear shrinking surface.

Magnetic Nanocomposites for the Remote Activation of Sulfate Radicals for the Removal of Rhodamine B.

The widespread presence of numerous organic contaminants in water poses a threat to the ecological environment and human health. Magnetic nanocomposites exposed to an alternating magnetic field (AMF) have a unique ability for magnetically mediated energy delivery (MagMED) resulting from the embedded magnetic nanoparticles; this localized energy delivery and associated chemical and thermal effects are a potential method for removing contaminants from water. This work developed a novel magnetic nanocomposite-a polyacrylamide-based hydrogel loaded with iron oxide nanoparticles. For this magnetic nanocomposite, persulfate activation and the contamination removal in water were investigated. Magnetic nanocomposites were exposed to AMF with a model organic contaminant, rhodamine B (RhB) dye, with or without sodium persulfate (SPS). The removal of RhB by the nanocomposite without SPS as a sorbent was found to be proportional to the concentration of magnetic nanoparticles (MNPs) in the nanocomposite. With the addition of SPS, approximately 100% of RhB was removed within 20 min. This removal was attributed primarily to the activation of sulfate radicals, triggered by MNPs, and the localized heating resulted from the MNPs when exposed to AMF. This suggests that this magnetic nanocomposite and an AMF could be a unique environmental remediation technique for hazardous contaminants.

A comprehensive approach combining gradient porous metal foam and the magnetic field to regulate latent heat storage performance

This study proposes a comprehensive regulation method of gradient porous metal structure combined with the magnetic field to improve the controllability of heat utilization of latent heat thermal energy storage (LHTES) unit. Melting and solidification are considered. The enthalpy porosity method and magnetic force model describe the phase change of phase change material (PCM) and the movement of Fe3O4 nanoparticles under the magnetic field and assume the local thermal non-equilibrium model of metal foam. The numerical model is consistent with the visual experimental results of melting front evolution. The effects of magnetic nanoparticle concentration and gradient porosity on heat transfer and thermal energy change during melting and solidification are numerically studied. The results show that the phase change rate increases with the concentration of nanoparticles. The positive magnetic field further accelerates the phase change and heat energy change. The addition of copper foam considerably shortened the phase change time. The positive magnetic field accelerated the melting and heat energy change rate of PCM in copper foam by 18.2% and 23.1%, but the improvement of solidification was weak. Based on magnetic field promotion, the setting of porosity spacing with different gradients can regulate the phase interface uniformity, total heat energy, and heat energy change rate. Finally, according to different heat utilization scenarios of the LHTES system, this study gives recommended cases to optimize the performance of melting, solidification, and the phase change cycle.

Infrared-driven pyroelectric effect in magnetoelectric sensor for suspended on-chip magnetic nanoparticles quantification

Precise and real-time quantification of suspended magnetic nanoparticles (MNPs) is essential for augmenting the efficacy of the present MNP-based lab-on-a-chip systems. Existing MNP quantification techniques use bulky external electromagnets, which make such techniques expensive, energy-inefficient, and result in significant side effects on the surrounding healthy tissues. Here, we report on the development of an infrared-driven, Ni/lead magnesium niobate–lead titanate (PMN–PT) magnetoelectric (ME) heterostructure-based sensor that enables rapid assessment of the suspended MNPs in a fluidic environment without using an external magnetic field. The injected MNPs are captured by the generated magnetic field gradient of the Ni thin film. Subsequently, the optothermal-pyroelectric property of the underlying PMN–PT layer is utilized to quantitatively assess the MNPs' concentration. Under the incident infrared pulse at zero bias voltage, the device shows different transient photocurrent responses against varied MNP concentrations with a sensitivity of 0.29 nA mg−1 ml and a response time of less than 2 s. Such a ME device can improve the efficacy of current ME-based lab-on-a-chip systems, where a single device can capture, manipulate, as well as quantitatively assess the MNPs efficiently for critical biomedical applications such as drug delivery, drug regulation, and hyperthermia.

Effects of injection rates and tissue diffusivity in magnetic nano-particle hyperthermia.

Effects of injection rate and tumor physiology on the diffusion of magnetic nano-particles (MNPs) and temperature profile during magnetic hyperthermia are investigated in this work. The study considers three injection rates (2.5 μL/min, 10 μL/min, and 40 μL/min), and two MNP diffusion coefficients (10-9 m2/s and 10-11 m2/s). The simulation of this physics has been done on 3D tumor surrounded by healthy tissue. Transient MNP distribution in tissue is evaluated using Darcy's flow model and the MNP transport (convection-diffusion) equation. The temperature profile in the tumor model is computed by solving Penne's bioheat transfer equation (PBHTE). Results show tumors with high collagen content (with low MNP diffusivity) are more restrictive towards MNP transport than tumors having low collagen content. Thus, tumors with low MNP diffusivity need a higher injection rate to increase the homogeneity of MNP concentration as well as temperature profile during thermo-therapy. Results also show that, MNP fluid injected with a higher injection rate produces a more uniform MNP concentration up to greater depth than the lower injection rate.

Inductive Thermal Effect on Thermoplastic Nanocomposites with Magnetic Nanoparticles for Induced-Healing, Bonding and Debonding On-Demand Applications

In this study, the heating capacity of nanocomposite materials enhanced with magnetic nanoparticles was investigated through induction heating. Thermoplastic (TP) matrices of polypropylene (PP), thermoplastic polyurethane (TPU), polyamide (PA12), and polyetherketoneketone (PEKK) were compounded with 2.5–10 wt.% iron oxide-based magnetic nanoparticles (MNPs) using a twin-screw extrusion system. Disk-shape specimens were prepared by 3D printing and injection molding. The heating capacity was examined as a function of exposure time, frequency, and power using a radio frequency (RF) generator with a solenoid inductor coil. All nanocomposite materials presented a temperature increase proportional to the MNPs’ concentration as a function of the exposure time in the magnetic field. The nanocomposites with a higher concentration of MNPs presented a rapid increase in temperature, resulting in polymer matrix melting in most of the trials. The operational parameters of the RF generator, such as the input power and the frequency, significantly affect the heating capacity of the specimens, higher input power, and higher frequencies and promote the rapid increase in temperature for all assessed nanocomposites, enabling induced-healing and bonding/debonding on-demand applications.

Optimizing precision nanoparticle delivery for magneto-mechanically-based calcium modulation.

Modulating calcium influx events through mechanically actuated magnetic nanoparticles (MNPs) at the cell membrane or in the cytosol of neurons has been trending in the past few years. The mechanical force load is a critical parameter that can be fine-tuned through MNPs concentration and the incubation time. Commonly, MNPs get incubated for 24 h to improve the probability of neuronal uptake; however, critical cellular processes such as protein turnover also coincide during that time frame. Hence, we optimized the incubation time for MNPs to be below <24 h while showing similar calcium response events in neurons. To achieve this goal, we recorded transient calcium fluorescence (Fluo-4 AM, 10x Leica DMI-8, 4 fps) in dissociated primary rat cortical neurons (at 14 days in vitro) with starch-amine functionalized MNPs (incubated for 4 h and 24 h) over 12 min, where a magnetic field actuated 40-80 pN forces on the MNPs from 4 min to 8 min. We decomposed the mean somatic calcium signals into a resting concentration (lower envelope) and calcium events (magnitude and frequency) and correlated them with the Sørenson-Dice. All data was compared with the Mann-Whitney U test (N = 4 cultures, single neuron cells: control = 2262, 4 h = 2424, 24 = 1062). Our results showed that both incubation times provided increases in resting concentration and calcium event frequency and decreased event magnitude and synchronous correlation in comparison to the control. Although similar, we observed that the 4 h incubation time increased the calcium event response with higher frequency and decreased event magnitudes and synchronous correlation when compared to the 24 h incubation. Altogether, our results show that shorter MNPs incubation times can make calcium influx more precise and potentially overcome adverse effects stemming from protein turnover.

Waste Plastic Nanomagnetite Pour Point Depressants for Heavy and Light Egyptian Crude Oil.

One of the most widely used plastics in the world's rapidly urbanizing population is polyethylene (PE). Globally, there is a growing demand for plastics. Polyethylene plastics do pollute and harm the environment. Although polyethylene is said to be nonbiodegradable, any chemical deterioration can take hundreds of years. This study intends to improve the crude oil property, precisely its pour point, by using polyethylene derived from waste products with magnetic nanoparticles (MNPs) and applying it to heavy and light crude oils. Forty crude oil samples were prepared by changing the PE additive concentration from 0.25 to 2% with 0-2.0% MNP concentration. Dynamic light scattering (DLS), gas chromatography, and photomicrographic techniques were employed during the study. DLS results revealed that nanoparticles of heavy (B) crude oil have bigger particle sizes than light (A) crude oil samples, and the overall distribution of the added nanoparticles was much better in light crude oil than in heavy crude oil. The photomicrographic results revealed that the treated samples using additives provided a significant wax crystal reduction compatible with the provided pour point results. The prepared sample of the treated light (A) crude oil provided a more extraordinary rheology performance than the heavy (B) crude oil. Moreover, prepared crude oil samples with PE additives and MNPs are effective as pour point depressants.

Theoretical Development in the Viscosity of Ferrofluid

Abstract The viscosity of ferrofluid has a vital role in liquid sealing of the hard disk drives, biomedical applications as drug delivery, hyperthermia, and magnetic resonance imaging. The theoretical expressions for ferrofluid viscosity and its limitation are presented in detail in this article. A qualitative comparison of the theoretical and experimental viscosity results is also shown. In the absence of a magnetic field, the viscosity of ferrofluid depends on the volume concentration of magnetic nanoparticles, including surfactant layers. However, the viscosity of ferrofluid due to stationary magnetic field depends on the angle between the applied magnetic field and vorticity in the flow. If this angle is 90 deg, then there is a maximum increase in the viscosity. When field frequency matches with the relaxation time, known as resonance condition, then there is no impact of an alternating magnetic field in the viscosity of ferrofluid. If the frequency of an alternating magnetic field is less than resonance frequency, then an alternating magnetic field increases the viscosity of ferrofluid. For diluted ferrofluid, present theoretical results of viscosity have good agreement with the experimental data.

Magnetic force microscopy study of induced magnetism in graphene nanoribbons influenced by magnetic nanoparticles

Nanoscale analysis of magnetic properties of graphene nanoribbons (GNRs) conjugated with magnetic nanoparticles has been studied in this work. The effect of varying concentrations of Fe3O4 and Ni nanoparticles on the magnetic domain structure of GNRs has been investigated using magnetic force microscopy (MFM). A variable external magnetic field was applied to the samples, and an evident variation in the domain structure with a change in the magnetic field was observed. It was found that magnetic properties and the imaged magnetic domain structure are influenced by the concentration of magnetic nanoparticles conjugated with GNRs. The vibrating sample magnetometry (VSM) studies support the nano-domain studies done using MFM such that the trend observed for the saturation magnetization obtained from vibrating sample magnetometry (VSM) matches that of the phase difference obtained using MFM.

Quantitative Study of the Effect of Nanoparticles on the Mechanical Properties of Colon Cancer Cells

Magnetic nanoparticles (MNPs) are often used as drug-carrying particles for targeted therapy of tumors. Studying their effects on cell activity and mechanical properties is of great significance for the targeted treatment of tumors. In this paper, we used a combination of atomic force microscopy (AFM) and fluorescent labeling to study the mechanical properties of cells after the endocytosis of MNPs. Colon cancer cells SW480 were selected to co-culture with MNPs with a particle size of 50 nm, and the cell viability was measured and systematically analyzed under different conditions. The results showed that the safe dose of MNPs to colon cancer cells SW480 was 50 µg/mL, and when the amount exceeded 50 µg/mL, the cell viability decreased significantly. Increase the concentration of MNPs step by step within the safe dose of 0-50 µg/mL. Through the analysis of a large number of data measured by AFM, the results show that the mechanical properties of cells change significantly with the increase of MNPs concentration. In this paper, the experimental results are analyzed by comparing concentration gradients. The concentrations are set to 0, 30, and 50 µg/mL , respectively, to verify the influence of MNPs on the mechanical properties of cells.

Effect of magnetic nanoparticles on magnetic field homogeneity

The mechanism of magnetic nanoparticles (MNPs) affecting magnetic field uniformity is studied in this work. The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method. The induced field of the single MNP is combined with the magnetic field distribution of magnetofluid. In the simulation, magnetic field uniformity is described by a statistical distribution. As the chemical shift (CS) and full width at half maximum (FWHM) of magnetic resonance (MR) spectrum can reflect the uniformity of magnetic field, the simulation is verified by spectrum experiment. Simulation and measurement results prove that the CS and FWHM of the MR spectrum are basically positively correlated with the concentration of MNPs and negatively correlated with the temperature. The research results can explain how MNPs play a role in MR by affecting the uniform magnetic field, which is of great significance in improving the temperature measurement accuracy of magnetic nanothermometers and the spatial resolution of magnetic particle imaging.

Superparamagnetic hyperthermia and cytotoxicity properties of bimagnetic core–shell nanoparticles synthesized by solvothermal reflux method

Magnetic properties of spinel ferrites nanoparticles (NPs) were well studied for various applications, including biomedical applications such as magnetic hyperthermia agents, magnetic resonance imaging (MRI) contrast agents, targeted drug delivery agents, etc., Magnetic properties of these nanoparticles were altered by metal cations substitution as well as variation of size and shape of nanoparticles. Here hard–soft magnetic materials based magnetic exchange coupled bimagnetic CoFe2O4-CaFe2O4, and CaFe2O4-CoFe2O4 core–shell nanoparticles (CSNPs) with narrow size distribution were synthesized to alter their magnetic properties. Structural, morphology, magnetic, superparamagnetic hyperthermia (SPHT), and cytotoxicity properties of these NPs were reported. Unimagnetic phase CoFe2O4, CaFe2O4 nanoparticles were also studied for comparison. Though CaFe2O4 macrocrystals crystallizes in orthorhombic structure, CaFe2O4 nanocrystals crystallizes in cubic spinel structure whereas both macro- and nanoparticles of CoFe2O4 crystallizes in spinel structure. Scanning electron nanographs (electrongraphs) of all samples show narrow size distributed spherical particles of average particle size of around 10 nm and is confirmed by transmission electron nanographs. Room temperature magnetic hysteresis loop of all samples were shown superparamagnetic nature with very low coercive field. Bimagnetic CSNPs show higher specific heat generation rate (SHR) or specific magnetic field energy absorption rate (SAR) of superparamagnetic nanoparticles (474 W/g for CaFe2O4-CoFe2O4 CSNPs under H = 35.5 kAm−1 and f = 316 kHz field parameters ) compared to counterpart unimagnetic nanoparticles (407 W/g for CaFe2O4 NPs). However, the SAR decreases with increase of magnetic nanoparticles (MNPs) concentration in the dispersion medium due to reduced superparamagnetic relaxation time resulting from magnetic dipole interactions among dispersed nanoparticles. This is also confirmed in SPHT properties of dispersant removed CSNPs. Cytotoxicity studies show that cell viability increases with MNPs concentration due to increased colorimetric interference of iron oxide and inhomogeneous distribution of MNPs, due to magnetic interactions, among cell culture wells, at higher concentration. These CSNPs may be used for localized SPHT in cancer therapy.

Numerical study of convective heat transfer and particle distribution subject to magneto-static field in a square cavity

Magnetic nanoparticle suspension has been applied in a variety of energy transport systems due to its excellent flowing characteristics and extraordinary thermal conductivity, and it has proven to significantly influence the sustainable development of energy and the environment. This work aims to focus on the thermal, fluidic properties of the magnetic nanofluid while also considering the coupling factors of magnetic field, thermal exchange, fluidity and nanoparticle concentration. Firstly, the simulation results of velocity and temperature distribution will be validated using the finite element method, which is in accordance with previous results of natural convection in a square cavity. The analysis model of developed magneto-hydrodynamics heat transfer will then be constructed with the explanation of entropy and concentration distribution. In comparison to natural convection, the magnetic field-enhanced method is able to break through the limit of thermal exchange efficiency. In addition, when the magnetic field is increased to 30 kA/m, the thermodynamic force is replaced by magnetic volumetric force and this plays a role in the heat transfer of the cavity, while the average Nusselt numbers increase by 17% in comparison to natural convection performance (Ra = 105). Entropy generation increases as magnetic field strength increases as a result of the enhancement to circulation and temperature gradient in the nanofluid. This work utilises an advanced strategy for the convection performance of magnetic nanofluid and analyses the multi-physical field.

Electrospinning as a method for preparation of redispersible dry product with high content of magnetic nanoparticles

One of the key technological challenges in the development of iron-oxide-based magnetic nanoparticles (MNPs) is their long-term physical stability in colloidal dispersions. This can be improved by their transformation into a dry form. Here, we introduce electrospinning as a drying method for ethanol-based and water-based MNP dispersions, which enables the preparation of high-loaded dry MNP products. The obtained easily dispersible electrospun product contained up to 50 % (w/w) of MNPs, homogeneously distributed in the fibrillar structure, which is much more compared to the products of currently available methods for drying MNP dispersions. The polymers used as building blocks of nanofibers, namely poloxamer 188 and polyethylene oxide, improved the tolerance of MNPs to high ionic strength dispersion medium and thus enhanced the short-term physical stability of MNP dispersions after reconstitution. The dry product was stable for up to 1 month at room temperature and relative humidity up to 70 %. It was in the form of a nanofiber mat, which prevented the aerosolization of MNPs and their unintentional ambient exposure. Therefore, the electrospun product with MNPs is expected to be a safer dry formulation of MNPs than the nanoparticulate powders, which are usually the final products of the conventional drying methods.

Developing magnetorelaxometry imaging for human applications

Objective. Magnetic nanoparticles (MNPs) are a promising tool in biomedical applications such as cancer therapy and diagnosis, where localization and quantification of MNP distributions are often mandatory. This can be obtained by magnetorelaxometry imaging (MRXI). Approach. In this work, the capability of MRXI for quantitative imaging of MNP inside larger volumes such as a human head is investigated. We developed a human head phantom simulating a glioblastoma multiforme (GBM) tumor containing MNP for magnetic hyperthermia treatment. The sensitivity of our MRXI setup for detection of MNP concentrations in the range of 3–19 mg cm−3 was studied. Main result. The results show the high capability of MRXI to detect MNPs in a human head sized volume. Superficial sources with a concentration larger than 12 mg cm-3 could be reconstructed with a resulotion of about 1 cm-3. Significance. The reconstruction of the MNP distribution, mimicking a GBM tumor of 7 cm3 volume with clinically relevant iron concentration, demonstrates the in vivo feasibility of MRXI in humans.

Effect of Cobalt Ferrite Nanoparticles in a Hydrophilic Shell on the Conductance of Bilayer Lipid Membrane.

We measured the conductance of bilayer lipid membranes of diphytanoylphosphatidylcholine induced by interaction with cubic magnetic nanoparticles (MNPs) of cobalt ferrite 12 and 27 nm in size and coated with a hydrophilic shell. The MNP coating is human serum albumin (HSA) or polyethylene glycol (PEG). The interaction of nanoparticles added to the bulk solution with the lipid bilayer causes the formation of metastable conductive pores, which, in turn, increases the integral conductance of the membranes. The increase in conductance with increasing MNP concentration was practically independent of the particle size. The dependence of the bilayer conductance on the concentration of PEG-coated MNPs was much weaker than that on the concentration with a shell of HSA. Analyzing the current traces, we believe that the conductive pores formed as a result of the interaction of nanoparticles with the membrane can change their size, remaining metastable. The form of multilevel current traces allows us to assume that there are several metastable pore states close in energy. The average radius of the putative cylindrical pores is in the range of 0.4-1.3 nm.

Thermoacoustic concentration imaging of magnetic nanoparticles under single-pulse magnetic fields

Under a single-pulse magnetic field (SMF), we proposed a thermoacoustic (TA) concentration imaging method of magnetic nanoparticles (MNPs). This method derived the relationship between the concentration of MNPs and TA signals based on the mechanism of the TA effect. In the simulation, we ideally reconstructed the concentration map of the MNPs from the simulated TA signals. It proves the feasibility of the proposed method. In the experiment, a multi-channel acquisition system was built, and the MNP suspension with the iron concentration of 1 mg/ml was injected into two gaps of the phantom. Then, 128 TA signals were obtained by a multi-channel acquisition system. Finally, the imaging results faithfully reconstructed the cross-sectional image of the MNP area in the phantom. It is demonstrated that the TA concentration imaging of the MNPs under the SMF has the potential to achieve low-concentration MNP imaging in vivo, which provides a promising molecular imaging method for imaging MNP-labeled cancer tissues.

Scanning magnetometer based on magnetoimpedance sensor for measuring a remnant magnetization of printed toners

In this work, a scanning magnetometer based on a giant magnetoimpedance sensor was used to study the toner material of a black-and-white laser printer that contains iron oxide nanoparticles. We measured the local perpendicular magnetic field component of various sizes black toner strips, magnetized in a perpendicular magnetic field. Our calibration samples were two-wire current lines, which are the current analogue of magnetized toner strips. Magnetic images of the samples were obtained. It was found that investigated toner samples have an average concentration of magnetic nanoparticles per unit area of order of 6 μg/mm2. At this concentration of nanoparticles, the remnant magnetic moment of the sample 1.6 × 5 mm2 in size was about of 0.046 µA⋅m2 and could be reliably registered by the scanning magnetometer. The magnetic image of the toner sample was compared with a hysteresis loop obtained using a vibrating sample magnetometer.

Inverse problem of magneto-acoustic concentration tomography for magnetic nanoparticles with magnetic induction in a saturation magnetization state based on the least squares QR factorization method-trapezoidal method.

In order to improve the imaging quality of magneto-acoustic concentration tomography for magnetic nanoparticles (MNPs) with magnetic induction (MACT-MI) and overcome the boundary singularity, this paper built a matrix model which shows the relationship between the partial derivative distribution of MNP concentration and the ultrasound signals, and focused on proposing a concentration reconstruction method based on the least squares QR factorization (LSQR) method-trapezoidal method. Firstly, simulation models with different shapes were established. Secondly, the magnetic and acoustic field simulation data was substituted into the inverse problem method based on LSQR-trapezoidal method for concentration reconstruction. Finally, the reconstructed images were analyzed and the effect of MNP cluster radius on the reconstruction was investigated. Considering the diffusely asymptotic concentration distribution of MNPs in actual biological tissue environment, an asymptotic concentration model was established and the reconstructed images were analyzed. The simulation results show that under the same conditions, compared with the reconstruction method based on the method of moments (MoM), LSQR-trapezoidal method has clearer image boundaries, more stable imaging results, and faster imaging speed. Compared with the uniform concentration model, LSQR-trapezoidal method is more applicable to the asymptotic concentration model. This study provides a basis for further reconstruction of the accuracy of experimental research.