Use Of Magnetic Particles Research Articles

Multi-focused electric and magnetic field sourcing from an azimuthally polarized vortex circular hyperbolic umbilic beam.

In this paper, one kind of multi-focusing electric and magnetic field which is sourced from an azimuthally polarized vortex circular hyperbolic umbilic beam (APVCHUB) is presented. After passing through a high NA objective, both the electric and magnetic fields of the APVCHUBs will focus multiple times, and a high-purity longitudinal magnetic field (p q =80%) will be generated. Besides, the mutual induction of the vortex phase and azimuthal polarization changes the electric and magnetic fields' vibration state and intensity distribution, making the longitudinal magnetic field carry an m-order concentric vortex. Our findings suggest that the APVCHUB could have potential applications in magnetic particle manipulation, extremely weak magnetic detection, data storage, semiconductor quantum dot excitation, etc.

NH2-Functionalized Magnetic Nanoparticles for the N-Glycomic Analysis of Patients with Multiple Sclerosis.

Glycosylation is vital for well-functioning glycoproteins and is reportedly altered in chronic inflammatory disorders, including multiple sclerosis (MS). High-throughput quantitative measurement of protein glycosylation is challenging, as glycans lack fluorophore groups and require fluorescent labeling. The attachment of fluorescent tags to each glycan moiety necessitates sample clean-up for reliable quantitation. The use of magnetic particles in glycan sample preparation is reportedly an easy-to-use solution to accomplish large-scale biomarker discovery studies. In this study, NH2-funtionalized magnetic nanoparticles were synthetized, characterized and applied for the glycosylation analysis of serum samples from patients diagnosed with multiple sclerosis and corresponding healthy controls. Serum samples were PNGase F digested and labeled by procainamide via reductive amination, followed by magnetic nanoparticle-based purification. The prepared samples were analyzed by hydrophilic interaction liquid chromatography, allowing for the relative quantitation of the individual glycan species. Significant glycosylation alterations were detected between MS patients and healthy controls, especially when analyzing the different gender groups.

Abstract 2948: A multimodal, label-free tool for gentle and efficient cell separation

Abstract LevitasBio has developed the LeviCell™ platform, a powerful new technology for cell separation and characterization that utilizes magnetic fields to levitate cells. Unlike other methods, cell separation via magnetic levitation does not require dyes, antibodies or specific markers, and the cells are not modified or perturbed in any fashion. However, magnetic levitation also does not preclude the use of these tools to further enhance separation of cells. In its simplest form, magnetic levitation requires only the addition of an inert paramagnetic compound to the media in which the cells are suspended. The cells are subsequently introduced into an externally applied magnetic field while contained within a single-use cartridge, which causes the cells to levitate in solution. The cells’ intrinsic properties, including density and magnetic susceptibility, determine the height to which the cells levitate. As different cell types often have different such properties, they may often levitate to different heights, facilitating their separation. Continuous imaging allows for complete sample analysis and characterization with the benefit of real-time control over the cell separation. The simplicity of magnetic levitation enables cells to be treated gently without use of high pressure or other perturbations that commonly lead to increased cellular stress responses, specific cell type activation, or even cell death. The direct and gentle flow path leads to high yields of live cells even with very low input cell numbers. This novel cell separation technology enables a variety of applications, including: the enrichment of viable cells from dead/dying cells and debris; separation of different cell types possessing distinct densities; and, in cases where the intrinsic density changes, the separation of differentiated from undifferentiated cells. Given that the levitation chamber is flanked by two magnets on the top and bottom, the levitation technology also inherently allows for the use of magnetic particles to deplete undesired cells within a cell population. Here we illustrate the performance of anti-CD45 antibody-conjugated magnetic particles for CD45+ cell depletion with the LeviCell system. CD45+ depletion rates of greater than 99% are readily obtained across a wide range of total CD45+ input cell numbers, from 105 to 107 total cells. Furthermore, CD45+ cell depletion is performed simultaneously with live cell enrichment, allowing for the collection of a high viability CD45- live cell population. Citation Format: Kevin Travers, Chris Stevens, Susana Jett, Suzanne Weaver, Teddy de Groot, Stefan Ha, Geoff Facer, Kathy Lazaruk. A multimodal, label-free tool for gentle and efficient cell separation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2948.

Ultrasensitive lateral flow immunoassay of phycotoxin microcystin-LR in seafood based on magnetic particles and peroxidase signal amplification

In this study, an immunochromatographic test system for the ultrasensitive and rapid detection of the highly toxic phycotoxin microcystin-leucine-arginine (MC-LR) has been developed. The lateral flow immunoassay (LFIA) is based on an indirect competitive format with the use of magnetic particles (MPs) as a colored label for secondary antibodies and a carrier for horseradish peroxidase (HRP) as a means of signal amplification. A simple method of simultaneous covalent binding of antibodies and HRP to the surface of MPs was applied. The developed test system allows for the detection of MC-LR with an instrumental detection limit of 2 pg/mL and cutoff of 50 pg/mL within 17 min. A high specificity of the LFIA has been demonstrated: the cross-reactivity with MC-LR structural analogs was negligible. A technique for sample preparation of various seafood samples was proposed. The applicability of the LFIA for the control of MC-LR contamination of shrimp, octopus, squid, and mussels has been confirmed. The assay recoveries ranged from 71% to 115%. The developed approach is of great potential as a universal tool that can be applied to a wide range of analytes.

On the use of magnetic particles to enhance the flow of vibrated grains through narrow apertures

The flow of grains through narrow apertures possess an extraordinary challenge: clogging. Strategies to alleviate the effect of clogging, such as the use of external vibration or addition of smaller grains, are always part of the design of machinery for the handling of bulk materials. In this work, we study with numerical simulations the effect of adding self-repelling magnetic particles to a sample of grains. We consider a vibrated two-dimensional hopper with a small orifice through which disks flow and clog intermittently. We find that the magnetic repulsion has a second order effect in comparison with the effect of the size of the added grains. Small added grains ease the flow of the original species. However, when the magnetic repulsion is switched on for the added small grains their “lubricating” effect is usually lessened. Only for a narrow range of sizes of the added particles we observe a subtle improvement of flow rate of the original particles with magnetic repulsion.

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods.

The remediation of water streams, polluted by various substances, is important for realizing a sustainable future. Magnetic adsorbents are promising materials for wastewater treatment. Although numerous techniques have been developed for the preparation of magnetic adsorbents, with effective adsorption performance, reviews that focus on the synthesis methods of magnetic adsorbents for wastewater treatment and their material structures have not been reported. In this review, advancements in the synthesis methods of magnetic adsorbents for the removal of substances from water streams has been comprehensively summarized and discussed. Generally, the synthesis methods are categorized into five groups, as follows: direct use of magnetic particles as adsorbents, attachment of pre-prepared adsorbents and pre-prepared magnetic particles, synthesis of magnetic particles on pre-prepared adsorbents, synthesis of adsorbents on preprepared magnetic particles, and co-synthesis of adsorbents and magnetic particles. The main improvements in the advanced methods involved making the conventional synthesis a less energy intensive, more efficient, and simpler process, while maintaining or increasing the adsorption performance. The key challenges, such as the enhancement of the adsorption performance of materials and the design of sophisticated material structures, are discussed as well.

Fractional model of MHD blood flow in a cylindrical tube containing magnetic particles

In recent years, the use of magnetic particles for biomedicine and clinical therapies has gained considerable attention. Unique features of magnetic particles have made it possible to apply them in medical techniques. These techniques not only provide minimal invasive diagnostic tools but also transport medicine within the cell. In recent years, MRI, drug supply to infected tissue, Hyperthermia are more enhanced by the use of magnetic particles. The present study aims to observe heat and mass transport through blood flow containing magnetic particles in a cylindrical tube. Furthermore, the magnetic field is applied vertically to blood flow direction. The Caputo time fractional derivative is used to model the problem. The obtained partial fractional derivatives are solved using Laplace transform and finite Hankel transform. Furthermore, the effect of various physical parameters of our interest has also been observed through various graphs. It has been noticed that the motion of blood and magnetic particles is decelerated when the particle mass parameter and the magnetic parameter are increased. These findings are important for medicine delivery and blood pressure regulation.

Scavenging of bacteria or bacterial products by magnetic particles functionalized with a broad-spectrum pathogen recognition receptor motif offers diagnostic and therapeutic applications

Sepsis is a dysregulated host response of severe bloodstream infections, and given its frequency of occurrence and high mortality rate, therapeutic improvements are imperative. A reliable biomimetic strategy for the targeting and separation of bacterial pathogens in bloodstream infections involves the use of the broad-spectrum binding motif of human GP-340, a pattern-recognition receptor of the scavenger receptor cysteine rich (SRCR) superfamily that is expressed on epithelial surfaces but not found in blood. Here we show that these peptides, when conjugated to superparamagnetic iron oxide nanoparticles (SPIONs), can separate various bacterial endotoxins and intact microbes (E. coli, S. aureus, P. aeruginosa and S. marcescens) with high efficiency, especially at low and thus clinically relevant concentrations. This is accompanied by a subsequent strong depletion in cytokine release (TNF, IL-6, IL-1β, Il-10 and IFN-γ), which could have a direct therapeutic impact since escalating immune responses complicates severe bloodstream infections and sepsis courses. SPIONs are coated with aminoalkylsilane and capture peptides are orthogonally ligated to this surface. The particles behave fully cyto- and hemocompatible and do not interfere with host structures. Thus, this approach additionally aims to dramatically reduce diagnostic times for patients with suspected bloodstream infections and accelerate targeted antibiotic therapy. Statement of significanceSepsis is often associated with excessive release of cytokines. This aspect and slow diagnostic procedures are the major therapeutic obstacles. The use of magnetic particles conjugated with small peptides derived from the binding motif of a broad-spectrum mucosal pathogen recognition protein GP-340 provides a highly efficient scavenging platform. These peptides are not found in blood and therefore are not subject to inhibitory mechanisms like in other concepts (mannose binding lectine, aptamers, antibodies). In this work, data are shown on the broad bacterial binding spectrum, highly efficient toxin depletion, which directly reduces the release of cytokines. Host cells are not affected and antibiotics not adsorbed. The particle bound microbes can be recultured without restriction and thus be used directly for diagnostics.

Tolerability to non-endosomal, micron-scale cell penetration probed with magnetic particles

The capability of HeLa cells to internalize large spherical microparticles has been evaluated by using inorganic, magnetic microparticles of 1 and 2.8 µm of diameter. In both absence but especially under the action of a magnet, both types of particles were uptaken, in absence of cytotoxicity, by a significant percentage of cells, in a non-endosomal process clearly favored by the magnetic field. The engulfed particles efficiently drive inside the cells chemically associated proteins such as GFP and human alpha-galactosidase A, without any apparent loss of protein functionalities. While 1 µm particles are completely engulfed, at least a fraction of 2.8 µm particles remain embedded into the cell membrane, with only a fraction of their surface in cytoplasmic contact. The detected tolerance to endosomal-independent cell penetration of microscale objects is not then restricted to organic, soft materials (such as bacterial inclusion bodies) as previously described, but it is a more general phenomenon also applicable to inorganic materials. In this scenario, the use of magnetic particles in combination with external magnetic fields can represent a significant improvement in the internalization efficiency of such agents optimized as drug carriers. This fact offers a wide potential in the design and engineering of novel particulate vehicles for therapeutic, diagnostic and theragnostic applications.

Metal-Organic Framework-Derived Carbon/Carbon Nanotubes Mediate Impedance Matching for Strong Microwave Absorption at Fairly Low Temperatures.

The use of magnetic particles and carbon materials, particularly those with compatible dielectric and magnetic loss, is crucial in managing microwave pollution. However, the mismatched impedance of currently available absorbers constrains their practical applications. Herein, we demonstrate the potential of a metal-organic framework (MOF)-derived composite whose impedance matching is optimized through spraying and immersion of MOF precursors in carbon nanotube socks followed by carbonization. The composite presents extremely strong microwave absorption with a reflection loss of -30 dB, a thin thickness of 1.5 mm, and a wide frequency bandwidth of 7.8 GHz. The excellent absorption can still be maintained even at a fairly low temperature of -40 °C. Such results are primarily attributed to the synergistic effect between the hierarchical architecture and multiple components that greatly optimizes the impedance matching. We believe that the composite is a promising microwave absorber that can help to solve the critical electromagnetic wave pollution.

Recent Trends in Enzyme Immobilization-Concepts for Expanding the Biocatalysis Toolbox.

Enzymes have been exploited by humans for thousands of years in brewing and baking, but it is only recently that biocatalysis has become a mainstream technology for synthesis. Today, enzymes are used extensively in the manufacturing of pharmaceuticals, food, fine chemicals, flavors, fragrances and other products. Enzyme immobilization technology has also developed in parallel as a means of increasing enzyme performance and reducing process costs. The aim of this review is to present and discuss some of the more recent promising technical developments in enzyme immobilization, including the supports used, methods of fabrication, and their application in synthesis. The review highlights new support technologies such as the use of well-established polysaccharides in novel ways, the use of magnetic particles, DNA, renewable materials and hybrid organic–inorganic supports. The review also addresses how immobilization is being integrated into developing biocatalytic technology, for example in flow biocatalysis, the use of 3D printing and multi-enzymatic cascade reactions.

Use of magnetic particles in the purification of IgM antibodies against Taenia solium.

The use of L protein coupled magnetic particles for the concentration and purification of immunoglobulin M (mIgM) monoclonal antibodies against Taenia solium was evaluated. Three concentration methods and different elution times were evaluated and the ratio of particles to the ratio of mIgM was optimized. It is demonstrated that: 1) with the use of magnetic particles, a previous concentration of mIgM is not required, which reduces the manipulation of the antibodies and improves the recovery, 2) the use of a binding buffer can be omitted, since the pH of most cell culture supernatants are neutral, and 3) longer elution times (~ 45 minutes) are needed to increase recovery to a level greater than 80%. The study demonstrates that the use of L protein-coupled magnetic particles is a simple and efficient tool for mIgM concentration and purification.

Numerical study of magnetic particles mixing in waste water under an external magnetic field

Abstract The combination of nanotechnology and microfluidics may offer an effective water and wastewater treatment. A novel approach combines the use of magnetic particles which can capture heavy metal impurities in microfluidic ducts. The purpose of this study is to investigate the mixing mechanism of two water streams, one with magnetic particles and the other with wastewater. The optimum mixing is obtained when particles are uniformly distributed along the volume of water in the duct for the combined action of a permanent, spatially and temporally aligned magnetic field. Results showed that mixing is enhanced as the frequency of the magnetic field decreases or its amplitude increases, while magnetic gradient is found to play an insignificant role in the present configuration. Moreover, for simulations with low frequency, the mean concentration of particles is found to be twice as high as compared to the cases with higher frequency. Optimum distribution of particles inside the micromixer is observed for the combination of 0.6 T, 8 T/m and 5 Hz for the magnetic magnitude, gradient and frequency, respectively, where concentration reaches the optimal value of 0.77 mg/mL along the volume of the duct.

Investigation on magnetization induced by tightly focused azimuthally polarized fractional vortex beam

All-optical magnetic recording based on the inverse Faraday effect has become a research hotspot in recent years due to its ultra-high storage density and ultra-fast magnetization reversal rate. Existing studies have shown that by optimizing the phase modulation or performing 4π tight focusing of azimuthally polarized vortex beams, high-resolution longitudinal magnetization fields with different axisymmetric intensity patterns can be generated. In order to meet the requirements of more complex all-optical magnetic recording and asymmetric magnetic particle capture and manipulation, it is particularly important to generate an asymmetric light-induced magnetization field with adjustable center position. Studies have shown that the fractional vortex phase could lead to the asymmetric focal field distribution generation under tight focusing conditions, which means that the tightly-focused azimuthally polarized light carrying the fractional vortex phase can produce a novel asymmetric light-induced magnetization field. As a new degree of freedom for the regulation of the magnetization field, the fractional topological charge will bring more new phenomena, new effects and new applications in the field of interaction between light and matter. In this work, for the first time to our knowledge, the magnetization induced by tightly focused azimuthally polarized fractional vortex beam is studied based on the Richard-Wolf vector diffraction theory and the inverse Faraday effect. The equivalent approximation of the magnetization induced by azimuthally polarized fractional vortex beam regarded as a weighted superposition of magnetization induced and crossly induced by a finite number of azimuthally polarized adjacent integer-order vortex beams, where the number of the equivalent terms is chosen by using the histogram intersection method of the intensity distribution image of the magnetization field. The magnetization field distribution under different values of <i>α</i> are also numerically simulated. Studies have shown that magnetization induced by the azimuthally polarized fractional vortex beam is asymmetrically distributed. When the fractional vortex topological charge α belongs to [0.5,1.5], as the vortex topological load increases, the splitting phenomenon of the transverse distribution of magnetization field appears with the magnetization spot position shift in the direction perpendicular to the optical axis. When <i>α</i> equals 0.5 or 1.5, the maximum offset of the center of the magnetization spot is 0.24<i>λ</i>. When the fractional vortex topological charge α belongs to [2,3], the transverse distribution of magnetization field splits two hot intensity spots with gradually growing outer ring diameter. When the fractional vortex topological charge <i>α</i> tends to be an integer 3, the transverse distribution of magnetization field also gets round and symmetrical. In particular, when the fractional vortex topological charge α is a half-integer, especially larger than 3. The number of hot spots (<inline-formula><tex-math id="M8">\begin{document}$\alpha - 0.5 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200269_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200269_M8.png"/></alternatives></inline-formula>) of the intensity of the magnetization field and the number of dark spots (<inline-formula><tex-math id="M9">\begin{document}$ \alpha - 1.5 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200269_M9.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="16-20200269_M9.png"/></alternatives></inline-formula>) surrounded by them all have a positive correlation with the number of vortex order. The research in this paper is expected to have new applications in the fields of all-optical magnetic recording and the capture and manipulation of magnetic particles.

Characterization of magnetic particles of azocasein-iron composite for protease purification

Research on magnetic particles has expanded over the years. These particles have several properties, such as low cost, fast preparation and use time, high surface area, and easy separation, which allow them to be employed in the purification of molecules, for example, enzymes. In this work, magnetic particles of azocasein-iron composite were produced, characterized and used in the purification of a microbial protease. The particle characterization was performed using the established techniques: X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). A purification rate of 11.64 was achieved by the use of magnetic particles in comparison to the crude extract. The recovery rate was very low but was higher when compared to the traditional, expensive, and slow DEAE-Sepharose column purification.

Magnetically Assisted Control of Stem Cells Applied in 2D, 3D and In Situ Models of Cell Migration.

The success of cell therapy approaches is greatly dependent on the ability to precisely deliver and monitor transplanted stem cell grafts at treated sites. Iron oxide particles, traditionally used in vivo for magnetic resonance imaging (MRI), have been shown to also represent a safe and efficient in vitro labelling agent for mesenchymal stem cells (MSCs). Here, stem cells were labelled with magnetic particles, and their resulting response to magnetic forces was studied using 2D and 3D models. Labelled cells exhibited magnetic responsiveness, which promoted localised retention and patterned cell seeding when exposed to magnet arrangements in vitro. Directed migration was observed in 2D culture when adherent cells were exposed to a magnetic field, and also when cells were seeded into a 3D gel. Finally, a model of cell injection into the rodent leg was used to test the enhanced localised retention of labelled stem cells when applying magnetic forces, using whole body imaging to confirm the potential use of magnetic particles in strategies seeking to better control cell distribution for in vivo cell delivery.

Landfill leachate treatment by sorption in magnetic particles: preliminary study

Leachates are still an open issue in environmental protection. Many of the applied methods for their treatment present low efficiency and thus need to be used collectively. In practice reverse osmosis is mostly used, as it is the most effective option, regardless of its cost. Magnetic methods to treat effluents have been used for water and wastewater treatment by the use of magnetic particles together with magnetic separation for the removal of contaminants. However, large-scale applications are few or even non-existent when we deal with complex contaminated media such as landfill leachates, for which not even research studies at laboratorial scale with real samples have been done yet. In this work, we apply for the first time magnetic sorption for the treatment of leachates, and close the full cycle by studying the regeneration and re-use of the magnetic particles; we also study the influence of the concentration of magnetic particles, the use of several pre-treatment methodologies and the type of particle used in the process, in real landfill samples from the waste treatment plant of Salamanca (Spain), for the removal of COD, NO3−, NO2−, NH4+, Total-N, PO43−, SO42− and Cl−. Regeneration of the magnetic particles after being used in the sorption stage is also studied, as well as their efficiency regarding their re-use. It is also determined the optimum number of batches for complete desorption and for regeneration of the particles, the effect of successive regeneration and re-use cycles, the use of two different regeneration methods, the efficiency of the desorption, the effect of the quantity of solvent and the influence of the time of sorption. Due to its innovative character and the complexity of the media, this work represents a first preliminary approach and, although some promising results have been obtained, further studies are required to completely understand and evaluate the proposed treatment process.

Impact of shock loading with mid-stage pulping wastewater on a magnetic micro-aerobic activated sludge system

The effect of mid-stage pulping wastewater (as shock load) on micro-aerobic magnetic activated sludge system was studied. Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-stage wastewater for 16 days. “Recovery” experiments were conducted by using simulated wastewater for 12 days. Upon the addition of mid-stage wastewater, COD Cr removal pertaining to the use of magnetic particles reached 71.57% and remained above 80% in the “recovery” experiment. However, the efficiency of the reactor in the absence of magnetic particles was only 37.29%, and reached about 40% in the “recovery” experiment. After the micro-aerobic activated sludge was shocked, the flocculation performance and surface properties of the sludge were analyzed, and the results showed that all indicators of the reactors in the presence of magnetic particles were superior to those of reactors without magnetic particles. After 12 days of “recovery”, the indicators of the sludge pertaining to the reactors containing magnetic particles “recovered” completely.

Localized Manipulation of Magnetic Particles in an Ensemble

The ability to manipulate magnetic particles selectively and simultaneously (within a group of such particles) has significant implications in studying cellular behaviors and in manipulating micro-structures at an ensemble-level. The current magnetic manipulation techniques have been demonstrated to be effective for studying cell mechanics. However, they suffer from low throughput, as only one particle is addressed in an individual experiment. This renders them unsuitable for ensemble-level operations. In this paper, we present a magnetic manipulation system that enables (effectively) simultaneous yet localized manipulation of magnetic particles. The proposed system is equipped with a novel device, which realizes magnetic force localization. The properly localized force allows selective manipulation of a single magnetic particle in a group. The localization effects of this device are demonstrated and quantified through analytical modeling and simulations that yielded statistically meaningful results. With the characterized device, experiments were carried out to evaluate the effectiveness of the proposed system.

Modern magnetic immunoassay: Biophysical and biochemical aspects

In this review article an analysis of the biochemical and biophysical aspects of modern magnetic immunoassay (MIA) is conducted and additionally the problems and perspectives of its application in biology, biotechnology and medicine are defined. Magnetic immunoassay should be considered as an evolutionary extension of the classical immunoassay. MIA can have many variants of modifications, similar to the classic immunoenzymatic assay. The key distinctive element of the MIA is the use of magnetic particles (MPs), which are usually nanoparticles. MPs in the MIA can act as a marker for detection, or the solid phase at which the immunochemical reaction takes place. MIA possesses basic advantages over classical immunoassay methods: thanks to the unique magnetic properties of the MPs and the ability to manipulate it in the external magnetic field, it is possible to increase the informative value of the analysis (first of all, sensitivity and specificity), as well as the rigid requirements for “purity” of tested samples. For the purposes of immunoassay, magnetic particles of size from 10 to 200 nm are important, since such particles are in a superparamagnetic state, in the absence of strong magnetic fields; they are not agglomerated in a liquid medium. The size of the spherical particle determines the rate of sedimentation and mobility in the solution. The outer polymeric membrane serves as a matrix in which the surface functional groups are added, and also protects the core of the metal from the external environment. The outer shell may also consist of agarose, cellulose, porous glass, silicon dioxide etc. There are several strategies for the synthesis of nanoparticles: mechanical (dispersion), physical (gas phase deposition), wet chemical methods (chemical comprecipitation, thermal decomposition, methods of micro emulsion, hydrothermal reactions) and physico-chemical methods. Also used are magnesite nanoparticles of biogenic origin. Magnetic particles may function, and this is important for immunoassay. Surface functional groups include carboxylic, amino, epoxy, hydroxyl, tosyl, and N-hydroxysuccinate-activated groups. Magnetic spherical particles usually interact with surface molecules such as streptovidine, biotin, protein A, protein G, and immunoglobulin etc. Directions and prospects of the development of methods of magnetic immunoassay are determined, mainly, by the development of methods for detecting or influencing magnetic particles. In this case, the classical methods of detection are electrochemical methods, electrochemiluminescence, fluorescence. More modern ones include giant magnetoresistance, superconducting quantum interference devices, surface-enhanced Raman spectroscopy, biosensors based on nonlinear magnetization, magneto-PCR immunoassay. The current trend is to combine or integrate the application of various biochemical, physical, molecular and genetic, physico-chemical detection methods. In fact, all of these benefits undoubtedly open up broad prospects for the practical application of MIA in biology, biotechnology and medicine.