Magnetochemistry

45 pages, 10369 KiB

Open AccessReview

Basic Principles and Recent Advances in Magnetic Cell Separation

by Marie Frenea-Robin and Julien Marchalot

Magnetochemistry 2022, 8(1), 11; https://doi.org/10.3390/magnetochemistry8010011 - 14 Jan 2022

Cited by 54 | Viewed by 17233

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great [...] Read more.

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells. Full article

(This article belongs to the Special Issue Magnetic Cell Separation)

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9 pages, 691 KiB

Open AccessReview

Origin of Perovskite Multiferroicity and Magnetoelectric-Multiferroic Effects—The Role of Electronic Spin in Spontaneous Polarization of Crystals

by Isaac B. Bersuker

Magnetochemistry 2022, 8(1), 9; https://doi.org/10.3390/magnetochemistry8010009 - 11 Jan 2022

Cited by 3 | Viewed by 2493

Abstract

In this semi-review paper, we show that the multiferroic properties of perovskite ABO₃ crystals with B(dⁿ), n > 0, centers are fully controlled by the influence of the electronic spin on the local dipolar instability that triggers the spontaneous [...] Read more.

In this semi-review paper, we show that the multiferroic properties of perovskite ABO₃ crystals with B(dⁿ), n > 0, centers are fully controlled by the influence of the electronic spin on the local dipolar instability that triggers the spontaneous polarization of the crystal. Contrary to the widespread statements, the multiferroicity of these crystals does not emerge due to the addition of unpaired electrons (carrying magnetic moments) to the spontaneously polarizing crystal; the spin states themselves are an important part of the local electronic structure that determines the very possibility of the spontaneous polarization. This conclusion emerges from vibronic theory, in which the ferroelectricity is due to the cooperative interaction of the local dipolar distortions induced by the pseudo-Jahn-Teller effect (PJTE). The latter requires sufficiently strong vibronic coupling between ground and excited electronic states with opposite parity but the same spin multiplicity. The detailed electronic structure of the octahedral [B(dⁿ)O₆] center in the molecular orbital presentation shows how this requirement plays into the dependence of the possible perovskite magnetic, ferroelectric, and multiferroic properties on the number of d electrons, provided the criterion of the PJTE is obeyed. Revealed in detail, the role of the electronic spin in all these properties and their combination opens novel possibilities for their manipulation by means of external perturbations and exploration. In particular, it is shown that by employing the well-known spin-crossover phenomenon, a series of novel effects become possible, including magnetic-ferroelectric (multiferroic) crossover with electric-multiferroic, magnetic-ferroelectric, and magneto-electric effects, some of which have already been observed experimentally. Full article

(This article belongs to the Special Issue Magnetic Multiferroics)

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19 pages, 5337 KiB

Open AccessReview

The Origins and the Current Applications of Microfluidics-Based Magnetic Cell Separation Technologies

by Ozgun Civelekoglu, A. Bruno Frazier and A. Fatih Sarioglu

Magnetochemistry 2022, 8(1), 10; https://doi.org/10.3390/magnetochemistry8010010 - 11 Jan 2022

Cited by 9 | Viewed by 4419

Abstract

The magnetic separation of cells based on certain traits has a wide range of applications in microbiology, immunology, oncology, and hematology. Compared to bulk separation, performing magnetophoresis at micro scale presents advantages such as precise control of the environment, larger magnetic gradients in [...] Read more.

The magnetic separation of cells based on certain traits has a wide range of applications in microbiology, immunology, oncology, and hematology. Compared to bulk separation, performing magnetophoresis at micro scale presents advantages such as precise control of the environment, larger magnetic gradients in miniaturized dimensions, operational simplicity, system portability, high-throughput analysis, and lower costs. Since the first integration of magnetophoresis and microfluidics, many different approaches have been proposed to magnetically separate cells from suspensions at the micro scale. This review paper aims to provide an overview of the origins of microfluidic devices for magnetic cell separation and the recent technologies and applications grouped by the targeted cell types. For each application, exemplary experimental methods and results are discussed. Full article

(This article belongs to the Special Issue Magnetic Cell Separation)

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20 pages, 6998 KiB

Open AccessArticle

Steric Quenching of Mn(III) Thermal Spin Crossover: Dilution of Spin Centers in Immobilized Solutions

by Komala Pandurangan, Anthony B. Carter, Paulo N. Martinho, Brendan Gildea, Tibebe Lemma, Shang Shi, Aizuddin Sultan, Tia E. Keyes, Helge Müller-Bunz and Grace G. Morgan

Magnetochemistry 2022, 8(1), 8; https://doi.org/10.3390/magnetochemistry8010008 - 10 Jan 2022

Cited by 7 | Viewed by 3675

Abstract

Structural and magnetic properties of a new spin crossover complex [Mn(4,6-diOMe-sal₂323)]⁺ in lattices with ClO₄⁻, (1), NO₃⁻, (2), BF₄⁻, (3), CF₃SO₃⁻, (4), and Cl⁻ (5) [...] Read more.

Structural and magnetic properties of a new spin crossover complex [Mn(4,6-diOMe-sal₂323)]⁺ in lattices with ClO₄⁻, (1), NO₃⁻, (2), BF₄⁻, (3), CF₃SO₃⁻, (4), and Cl⁻ (5) counterions are reported. Comparison with the magnetostructural properties of the C₆, C₁₂, C₁₈ and C₂₂ alkylated analogues of the ClO₄⁻ salt of [Mn(4,6-diOMe-sal₂323)]⁺ demonstrates that alkylation effectively switches off the thermal spin crossover pathway and the amphiphilic complexes are all high spin. The spin crossover quenching in the amphiphiles is further probed by magnetic, structural and Raman spectroscopic studies of the PF₆⁻ salts of the C₆, C₁₂ and C₁₈ complexes of a related complex [Mn(3-OMe-sal₂323)]⁺ which confirm a preference for the high spin state in all cases. Structural analysis is used to rationalize the choice of the spin quintet form in the seven amphiphilic complexes and to highlight the non-accessibility of the smaller spin triplet form of the ion more generally in dilute environments. We suggest that lattice pressure is a requirement to stabilize the spin triplet form of Mn³⁺ as the low spin form is not known to exist in solution. Full article

(This article belongs to the Special Issue Molecular Spin Crossover Materials: Recent Trends, Emerging Properties and Applications)

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10 pages, 5499 KiB

Open AccessArticle

Manipulation of Time- and Frequency-Domain Dynamics by Magnon-Magnon Coupling in Synthetic Antiferromagnets

by Xing Chen, Cuixiu Zheng, Sai Zhou, Yaowen Liu and Zongzhi Zhang

Magnetochemistry 2022, 8(1), 7; https://doi.org/10.3390/magnetochemistry8010007 - 30 Dec 2021

Cited by 11 | Viewed by 3338

Abstract

Magnons (the quanta of spin waves) could be used to encode information in beyond Moore computing applications. In this study, the magnon coupling between acoustic mode and optic mode in synthetic antiferromagnets (SAFs) is investigated by micromagnetic simulations. For a symmetrical SAF system, [...] Read more.

Magnons (the quanta of spin waves) could be used to encode information in beyond Moore computing applications. In this study, the magnon coupling between acoustic mode and optic mode in synthetic antiferromagnets (SAFs) is investigated by micromagnetic simulations. For a symmetrical SAF system, the time-evolution magnetizations of the two ferromagnetic layers oscillate in-phase at the acoustic mode and out-of-phase at the optic mode, showing an obvious crossing point in their antiferromagnetic resonance spectra. However, the symmetry breaking in an asymmetrical SAF system by the thickness difference, can induce an anti-crossing gap between the two frequency branches of resonance modes and thereby a strong magnon-magnon coupling appears between the resonance modes. The magnon coupling induced a hybridized resonance mode and its phase difference varies with the coupling strength. The maximum coupling occurs at the bias magnetic field at which the two ferromagnetic layers oscillate with a 90° phase difference. Besides, we show how the resonance modes in SAFs change from the in-phase state to the out-of-phase state by slightly tuning the magnon-magnon coupling strength. Our work provides a clear physical picture for the understanding of magnon-magnon coupling in a SAF system and may provide an opportunity to handle the magnon interaction in synthetic antiferromagnetic spintronics. Full article

(This article belongs to the Special Issue Advances in Antiferromagnetic Spintronics)

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30 pages, 957 KiB

Open AccessReview

The Microscopic Mechanisms Involved in Superexchange

by Jacques Curély

Magnetochemistry 2022, 8(1), 6; https://doi.org/10.3390/magnetochemistry8010006 - 30 Dec 2021

Cited by 4 | Viewed by 2824

Abstract

In earlier work, we previously established a formalism that allows to express the exchange energy J vs. fundamental molecular integrals without crystal field, for a fragment A–X–B, where A and B are 3d¹ ions and X is a closed-shell diamagnetic ligand. [...] Read more.

In earlier work, we previously established a formalism that allows to express the exchange energy J vs. fundamental molecular integrals without crystal field, for a fragment A–X–B, where A and B are 3d¹ ions and X is a closed-shell diamagnetic ligand. In this article, we recall this formalism and give a physical interpretation: we may rigorously predict the ferromagnetic (J < 0) or antiferromagnetic (J > 0) character of the isotropic (Heisenberg) spin-spin exchange coupling. We generalize our results to nd^m ions (3 ≤ n ≤ 5, 1 ≤ m ≤ 10). By introducing a crystal field we show that, starting from an isotropic (Heisenberg) exchange coupling when there is no crystal field, the appearance of a crystal field induces an anisotropy of exchange coupling, thus leading to a z-z (Ising-like) coupling or a x-y one. Finally, we discuss the effects of a weak crystal field magnitude (3d ions) compared to a stronger (4d ions) and even stronger one (5d ions). In the last step, we are then able to write the corresponding Hamiltonian exchange as a spin-spin one. Full article

(This article belongs to the Special Issue Computational Modelling of Magnetic Molecules and Multifunctional Magnetic Materials)

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18 pages, 4231 KiB

Open AccessArticle

Continuous Flow Labeling and In-Line Magnetic Separation of Cells

by Zhixi Qian, Thomas R. Hanley, Lisa M. Reece, James F. Leary, Eugene D. Boland and Paul Todd

Magnetochemistry 2022, 8(1), 5; https://doi.org/10.3390/magnetochemistry8010005 - 30 Dec 2021

Cited by 1 | Viewed by 2940

Abstract

There is an identified need for point-of-care diagnostic systems for detecting and counting specific rare types of circulating cells in blood. By adequately labeling such cells with immunomagnetic beads and quantum dots, they can be efficiently collected magnetically for quantification using fluorescence methods. [...] Read more.

There is an identified need for point-of-care diagnostic systems for detecting and counting specific rare types of circulating cells in blood. By adequately labeling such cells with immunomagnetic beads and quantum dots, they can be efficiently collected magnetically for quantification using fluorescence methods. Automation of this process requires adequate mixing of the labeling materials with blood samples. A static mixing device can be employed to improve cell labeling efficiency and eliminate error-prone laboratory operations. Computational fluid dynamics (CFD) were utilized to simulate the flow of a labeling-materials/blood mixture through a 20-stage in-line static mixer of the interfacial-surface-generator type. Optimal fluid mixing conditions were identified and tested in a magnetic bead/tumor cell model, and it was found that labeled cells could be produced at 1.0 mL/min flow rate and fed directly into an in-line magnetic trap. The trap design consists of a dual flow channel with three bends and a permanent magnet positioned at the outer curve of each bend. The capture of labeled cells in the device was simulated using CFD, finite-element analysis and magnetophoretic mobility distributions of labeled cells. Testing with cultured CRL14777 human melanoma cells labeled with anti-CD146 1.5 μm diameter beads indicated that 90 ± 10% are captured at the first stage, and these cells can be captured when present in whole blood. Both in-line devices were demonstrated to function separately and together as predicted. Full article

(This article belongs to the Special Issue Magnetic Cell Separation)

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23 pages, 9233 KiB

Open AccessArticle

Tailoring Magnetic and Transport Anisotropies in Co_100−x–Cu_x Thin Films through Obliquely Grown Nano-Sheets

by Cristina Favieres, José Vergara and Vicente Madurga

Magnetochemistry 2022, 8(1), 4; https://doi.org/10.3390/magnetochemistry8010004 - 28 Dec 2021

Cited by 5 | Viewed by 2365

Abstract

The magnetic and transport properties of pulsed laser-deposited Co_100−x–Cu_x thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous [...] Read more.

The magnetic and transport properties of pulsed laser-deposited Co_100−x–Cu_x thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field H_k remained constant for x = 0, 5 and 10, H_k ≈ 35 kAm⁻¹, and decreased to 28 and 26 kAm⁻¹ for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field H_c increased when x increased, from 200 (x = 0) to 1100 Am⁻¹ (x = 30). In contrast, in obliquely deposited films, H_c decreased from 1500 (x = 0) to 100 Am⁻¹ (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition. Full article

(This article belongs to the Special Issue Soft and Hard Magnetic Materials: Latest Advances and Prospects)

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18 pages, 4451 KiB

Open AccessReview

The Advantages of EPR Spectroscopy in Exploring Diamagnetic Metal Ion Binding and Transfer Mechanisms in Biological Systems

by Shelly Meron, Yulia Shenberger and Sharon Ruthstein

Magnetochemistry 2022, 8(1), 3; https://doi.org/10.3390/magnetochemistry8010003 - 26 Dec 2021

Cited by 6 | Viewed by 4619

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has emerged as an ideal biophysical tool to study complex biological processes. EPR spectroscopy can follow minor conformational changes in various proteins as a function of ligand or protein binding or interactions with high resolution and sensitivity. Resolving [...] Read more.

Electron paramagnetic resonance (EPR) spectroscopy has emerged as an ideal biophysical tool to study complex biological processes. EPR spectroscopy can follow minor conformational changes in various proteins as a function of ligand or protein binding or interactions with high resolution and sensitivity. Resolving cellular mechanisms, involving small ligand binding or metal ion transfer, is not trivial and cannot be studied using conventional biophysical tools. In recent years, our group has been using EPR spectroscopy to study the mechanism underlying copper ion transfer in eukaryotic and prokaryotic systems. This mini-review focuses on our achievements following copper metal coordination in the diamagnetic oxidation state, Cu(I), between biomolecules. We discuss the conformational changes induced in proteins upon Cu(I) binding, as well as the conformational changes induced in two proteins involved in Cu(I) transfer. We also consider how EPR spectroscopy, together with other biophysical and computational tools, can identify the Cu(I)-binding sites. This work describes the advantages of EPR spectroscopy for studying biological processes that involve small ligand binding and transfer between intracellular proteins. Full article

(This article belongs to the Special Issue EPR Spectroscopy in Chemistry and Biology)

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12 pages, 2427 KiB

Open AccessArticle

An Uneven Chain-like Ferromagnetic Copper(II) Coordination Polymer Displaying Metamagnetic Behavior and Long-Range Magnetic Ordering

by Cai-Ming Liu and You Song

Magnetochemistry 2022, 8(1), 2; https://doi.org/10.3390/magnetochemistry8010002 - 23 Dec 2021

Cited by 4 | Viewed by 5522

Abstract

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu₃(L)₂(N₃)₄(H₂O)₃)_n (1, HL = 6-hydroxynicotinic acid). It is the [...] Read more.

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu₃(L)₂(N₃)₄(H₂O)₃)_n (1, HL = 6-hydroxynicotinic acid). It is the first example of one-dimensional (1D) chain-like copper(II) coordination polymer showing both metamagnetic behavior and long-range magnetic ordering (T_c = 6.7 K), thanks to the interchain hydrogen bonds, which make a three-dimensional (3D) supramolecular array of the entire molecular structure and mediate the interchain antiferromagnetic interaction. Full article

(This article belongs to the Section Magnetic Materials)

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19 pages, 2586 KiB

Open AccessArticle

Correlation between Supramolecular Connectivity and Magnetic Behaviour of [Fe^III(5-X-qsal)₂]⁺-Based Salts Prone to Exhibit SCO Transition

by Bruno J. C. Vieira, Laura C. J. Pereira, Vasco da Gama, Isabel C. Santos, Ana C. Cerdeira and João C. Waerenborgh

Magnetochemistry 2022, 8(1), 1; https://doi.org/10.3390/magnetochemistry8010001 - 21 Dec 2021

Cited by 8 | Viewed by 2893

Abstract

We present an extensive study to determine the relationship between structural features of spin crossover (SCO) systems based on N-(8-quinolyl)salicylaldimine (qsal) ligand derivatives and their magnetic properties. Thirteen new compounds with general formula [Fe^III(5-X-qsal)₂]⁺ (X = H, F, [...] Read more.

We present an extensive study to determine the relationship between structural features of spin crossover (SCO) systems based on N-(8-quinolyl)salicylaldimine (qsal) ligand derivatives and their magnetic properties. Thirteen new compounds with general formula [Fe^III(5-X-qsal)₂]⁺ (X = H, F, Cl, Br and I) coupled to Cl⁻, ClO₄⁻, SCN⁻, PF₆⁻, BF₄⁻ and BPh₄⁻ anions were prepared and magnetically characterized. The structure/properties correlations observed in these compounds were compared to those of salts with the same [Fe^III(qsal-X)₂]⁺ cations previously reported in the literature. These cations favour the LS configuration in compounds with the weakest connectivity. As connectivity increases most of them present HS states at room temperature and structures may be described as arrangements of parallel layers of interacting cation dimers. All the compounds based on these cations undergoing complete SCO transitions within the 4–300 K temperature range have high intralayer connectivity. If, however, the interlayer connectivity becomes very strong they remain blocked in the HS or in the LS state. The SCO transition may be affected by the slightest change of solvent molecules content, disorder or even crystallinity of the sample and it remain difficult to predict which kind of ligand substituent should be selected to obtain compounds with the desired connectivity. Full article

(This article belongs to the Special Issue Photofunctional Molecular Magnets: Development and Their Potential Applications)

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Magnetochemistry, Volume 8, Issue 1 (January 2022) – 11 articles

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