Motion Of Magnetic Nanoparticles Research Articles

Magnetophoretic Effect on the Nanofluid Flow Over Decelerating Spinning Sphere with the Presence of Induced Magnetic Field

Magnetophoresis is the movement of magnetic nanoparticles under the guidance of magnetic field. Our goal is to perceive an unsteady magneto-nanofluid flow over a decelerating rotating sphere induced by an external magnetic field. In the flow analysis Brownian motion, thermophoresis and magnetopheresis effect are implemented in the model equations. At the boundary situation, zero-mass flux has been thought out. Utilizing similarity conversions we have converted the constitutive equations into ODEs and solve them numerically. The control of various factors on the flow properties has been staged through proper figures and tables. It is remarkably perceived that the magnetophoresis parameter increases the heat transmission ability of the fluid. Also, the magnetic-Prandtl number decreases the Nusselt number significantly. It is also professed that induced magnetic field elevates the heat transferability of the flow system and intensifies the velocity along the x-direction and diminishes the velocity along the z-direction.

Magnetofluidic mixing of a ferrofluid droplet under the influence of a time-dependent external field

Abstract

Magnetic Nanoparticles as a Tool for Remote DNA Manipulations at a Single-Molecule Level.

Remote control of cells and single molecules by magnetic nanoparticles in nonheating external magnetic fields is a perspective approach for many applications such as cancer treatment and enzyme activity regulation. However, the possibility and mechanisms of direct effects of small individual magnetic nanoparticles on such processes in magneto-mechanical experiments still remain unclear. In this work, we have shown remote-controlled mechanical dissociation of short DNA duplexes (18-60 bp) under the influence of nonheating low-frequency alternating magnetic fields using individual 11 nm magnetic nanoparticles. The developed technique allows (1) simultaneous manipulation of millions of individual DNA molecules and (2) evaluation of energies of intermolecular interactions in short DNA duplexes or in other molecules. Finally, we have shown that DNA duplexes dissociation is mediated by mechanical stress and produced by the movement of magnetic nanoparticles in magnetic fields, but not by local overheating. The presented technique opens a new avenue for high-precision manipulation of DNA and generation of biosensors for quantification of energies of intermolecular interaction.

Two-Phase Biofluid Flow Model for Magnetic Drug Targeting

Magnetic drug targeting (MDT) is a noninvasive method for the medical treatment of various diseases of the cardiovascular system. Biocompatible magnetic nanoparticles loaded with medicinal drugs are carried to a tissue target in the human body (in vivo) under the applied magnetic field. The present study examines the MDT technique in various microchannels geometries by adopting the principles of biofluid dynamics (BFD). The blood flow is considered as laminar, pulsatile and the blood as an incompressible and non-Newtonian fluid. A two-phase model is adopted to resolve the blood flow and the motion of magnetic nanoparticles (MNPs). The numerical results are obtained by utilizing a meshless point collocation method (MPCM) alongside with the moving least squares (MLS) approximation. The numerical results are verified by comparing with published numerical results. We investigate the effect of crucial parameters of MDT, including (1) the volume fraction of nanoparticles, (2) the location of the magnetic field, (3) the strength of the magnetic field and its gradient, (4) the way that MNPs approach the targeted area, and (5) the bifurcation angle of the vessel.

Squid‐Inspired Smart Window by Movement of Magnetic Nanoparticles in Asymmetric Confinement

AbstractThe camouflage used by cephalopods is an interesting topic in biomimetics. Squid, part of the cephalopod family, have transformable skin that can be made transparent or darkened through control of the light‐absorption area. This is achieved using a muscular structure. A smart‐window scheme inspired by this is developed. Magnetic nanopigments dispersed within an asymmetric pyramidal array are used and the light‐absorption area is manipulated through use of a magnetic field. Refractive‐index‐matched liquids are used as a dispersion media to avoid refraction at the interface. The transparency hysteresis (ON/OFF ratio) performance depends on the ratio of magnetic nanoparticles and the dispersive fluid and a model is derived to explain this. In addition, a 3D‐printed structure is proposed and demonstrated for better performance.

Movement of magnetic nanoparticles in brain tissue: mechanisms and impact on normal neuronal function

Magnetic nanoparticles (MNPs) have been used as effective vehicles for targeted delivery of theranostic agents in the brain. The advantage of magnetic targeting lies in the ability to control the concentration and distribution of therapy to a desired target region using external driving magnets. In this study, we investigated the behavior and safety of MNP motion in brain tissue. We found that MNPs move and form nanoparticle chains in the presence of a uniform magnetic field, and that this chaining is influenced by the applied magnetic field intensity and the concentration of MNPs in the tissue. Using electrophysiology recordings, immunohistochemistry and fluorescent imaging we assessed the functional health of neurons and neural circuits and found no adverse effects associated with MNP motion through brain tissue. From the Clinical EditorMuch research has been done to test the use of nanocarriers for gaining access across the blood brain barrier (BBB). In this respect, magnetic nanoparticles (MNPs) are one of the most studied candidates. Nonetheless, the behavior and safety of MNP once inside brain tissue remains unknown. In this article, the authors thus studied this very important subject.

Nanomechanical control of properties of biological membranes achieved by rodlike magnetic nanoparticles in a superlow-frequency magnetic field

It is proposed to use single-domain rodlike magnetic nanoparticles (MNPs) as mediators for nanomechanical control of properties of biological membranes and cells on the molecular or cellular level by exposing them to a homogeneous nonheating low-frequency magnetic field (AC MF). The trigger effect is achieved due to rotatory-oscillatory motion of MNPs in the AC MF, which causes the needed deformations in macromolecules of the membrane interacting with these MNPs.

Simulation of the Motion of Magnetic Nanoparticles in Human Tissues

In this paper an attempt on the basis of the theory of mobile cellular automata to develop a model of motion of magnetic nanoparticles in human organs and tissues. In the framework of the method of movable cellular automata, the simulated system (tissues and organs) is represented by an assembly of interacting automata (elements of finite size). The concept of the method is based on the introduction of a new state type – the state of a pair of automata. Setting various parameters of the medium (tissues and organs). We can vary behavior of these particles in these mediums.

Dielectrophoresis-Magnetophoresis Force Driven Magnetic Nanoparticle Movement in Transformer Oil Based Magnetic Fluids

Magnetic fluid is a stable colloidal mixture contained magnetic nanoparticles coated with a surfactant. Recently, it was found that the fluid has properties to increase heat transfer and dielectric characteristics due to the added magnetic nanoparticles in transformer oils. The magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength when the electric field is applied. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field. The behaviors of magnetic nanoparticles in both the fields must play an important role in changing the heat transfer and dielectric characteristics of the fluids. In this study, we visualized the movement of magnetic nanoparticles influenced by both the fields applied in-situ. It was found that the magnetic nanoparticles travel in the region near the electrode by the electric field and form long chains along the field direction by the magnetic field. It can be inferred that the movement of magnetic nanoparticles appears by both the fields, and the breakdown voltage of transformer oil based magnetic fluids might be influenced according to the dispersion of magnetic nanoparticles.

Spin-Spin and Spin-Lattice Relaxation of Protons in Ferrofluids Characterized With a High- $T_{\rm c}$ SQUID-Based NMR Spectrometer in Microtesla Fields

In this work, the relaxation rates of ferrofluids are characterized using a high-Tc SQUID-based nuclear magnetic resonance spectrometer in different field strengths and temperatures. It was found that the longitudinal relaxation rate, 1/T1, of ferrofluids measured in a high field strength is significantly higher than that measured in a low field strength. We attribute this to the magnetic-field gradients from the magnetization of magnetic nanoparticles that accelerate the T1-relaxation more in a high strength of magnetic fields than they are in a low strength of magnetic fields. Furthermore, T1 and T2 decrease when temperature increases, where T2 is the transverse relaxation time. This is due to the improved field-homogeneity seen by protons' spins at high temperatures, attributed to the enhanced Brownian motion of magnetic nanoparticles. Characterizing the relaxation rates will be helpful for further use of ferrofluids as contrast agents in low-field MR imagings.

Visualization on the behavior of nanoparticles in magnetic fluids under the electric field

The dielectric breakdown characteristics of magnetic fluids can be influenced by the magnetic nanoparticles included because their properties should be affected by the applied electric field. Based on measuring the dielectric breakdown voltage of magnetic fluids, we found that it is higher than that of the pure transformer oil in the case of the specific volume concentrations of magnetic nanoparticles. It is known from a numerical simulation that the conductive nanoparticles might behavior as electron scavengers in the electrically stressed magnetic fluids and change fast electrons into slowly negative charged nanoparticles for the electrical breakdown. In this study, we focus on the motion of magnetic nanoparticles in the fluids under the electric field applied by the visualization using a microchannel and an optical microscope.

Brownian motion of magnetic nanoparticles as a source of energy?

Brownian motion of magnetic nanoparticles in a low–density gas can induce random voltage pulses in a microscopic electric circuit containing a high–number–of–turns coil and a classical diode rectifier. The amplitude of the voltage pulses is estimated and the rectification condition examined. We have shown that in our toy–model nanogenerator where the motion of the magnetic nanoparticle is restricted to one–dimensional rotation around its vertical axis and the nanoparticle is inserted into a very low number–density gas (3 × 1016 m-3) one can generate voltage pulses of the amplitude of 3 × 10-8 V in one coil turn. The total number of 106 turns is then necessary to reach the rectifying region.