Magnetic Nanoparticles: Synthesis, Anisotropy, and Applications

Doped magnetic nanoparticles: From synthesis to applied technological frontiers

Doped magnetic nanoparticles (DMNPs) have become a fascinating class of nanomaterials with important implications in science and technology. The comprehensive review focuses on the synthetic methods, types of doping elements, distinctive properties, and extensive applications of DMNPs. The synthesis section highlights different methods, highlighting their benefits and drawbacks, such as chemical precipitation, co-precipitation, thermal breakdown, sol-gel, and other processes. Strategies for increasing the stability and functioning of DMNP are also reviewed, including surface functionalization and ligand exchange. An in-depth study is done to clarify how doping materials including transition metals, non-metals, and rare earth elements affect the chemical stability and magnetic characteristics of DMNP. Applications in various fields, such as biomedicine (MRI contrast agents, medication transport, antibacterial activity), environmental remediation (water purification, heavy metal removal), and sensing technologies, heavily rely on these features. DMNPs offer much potential in a variety of disciplines. Still, there are several challenges to their adoption, including regulatory and safety concerns, cost-effectiveness issues, and scalability issues. More research is required to overcome these difficulties and maximize the use of MDNPs for ensuring food safety.

Urchin-like magnetic nanoparticles loaded with type X collagen siRNA and Stattic to treat triple negative breast cancer under rotating magnetic field like an "enchanted micro-scalpel"

Magnetic nanoparticles effectively target drug delivery, contrast agents, biosensors, and more. Urchin-like magnetic nanoparticles (UMN) with abundant spike-like structures exhibit superior magneto-mechanical force to destroy tumor cells compared with other shapes of magnetic nanoparticles. However, when cell contents are released from tumor cells induced by magneto-mechanical force, they can act on surrounding tumor cells to facilitate tumor development. Therefore, multifunctional UMN is necessary. Interleukin-6 (IL-6) is an important inflammatory factor which is released after cell rupture, it can activate the STAT3 signaling pathway to promote tumor progression. Type X collagen (COL10A1) is a significant component of the extracellular matrix, ranking second among all aberrant genes in triple negative breast cancer (TNBC), and its knockdown can suppress tumorigenesis and metastasis. Here, we built a rotating magnetic field (RMF) platform, and a novel UMN using a straightforward solvothermal method was synthesized, which was much simpler than existing method. Stattic (STAT3 inhibitor) and COL10A1 siRNA were loaded onto the UMN@PEI to form UMNP/St/si. The RMF drove UMNP/St/si disrupted the cell membrane, promoted cell death. The inhibitory effects of UMNP/St/si under RMF on TNBC were verified both in vitro and in vivo. Furthermore, despite the increase in IL-6 due to cell rupture, IL-6/STAT3 signaling pathway was inhibited by Stattic, compensating for the deficiency of magneto-mechanical force. Moreover, the underlying mechanical mechanism of UMNP/St/si after exposure to RMF was also analyzed. It suggests that UMNP/St/si is a promising and effective strategy for TNBC treatment and provides valuable insights for treating other diseases as well.

A Compendium of Magnetic Nanoparticle Essentials: A Comprehensive Guide for Beginners and Experts

Magnetic nanoparticles (MNPs) are advanced materials that combine the unique properties of magnetic materials and nanoscale dimensions, enabling a wide range of applications in biomedicine, environmental science, and information technology. This review provides a comprehensive yet accessible introduction to the fundamental principles, characterization techniques, and diverse applications of MNPs, with a focus on their nanoscale magnetic properties, such as superparamagnetism, single-domain behavior, and surface effects. It also delves into their classification and the critical role of parameters like magnetic anisotropy and blocking temperature. Emphasis is placed on routine characterization methods, including X-ray diffraction, electron microscopy, and magnetometry, as well as advanced concepts like magnetic hyperthermia and self-regulated heating. Designed for newcomers and experts alike, this review serves as both an educational guide and a quick-reference resource, ensuring clarity while maintaining scientific rigor.

Magnetic properties of different phases iron oxide nanoparticles prepared by micro emulsion-hydrothermal method

In this study, we report the synthesis of iron oxide nanoparticles (FeONPs) using micro-emulsion-hydrothermal method. By adjusting the synthesis temperature, we successfully produced FeO nanorods and nanospheres. In addition, the 2-octanol, and the surfactant cetyltrimethylammonium bromide served as a solvent in the synthesis process. Using iron nitrate hexahydrate as the salt precursor allowed for the formation of FeONPs with varied sizes, shapes and phases. The synthesized materials were extensively characterized using XRD, SEM, TEM, EDS, FTIR, and XPS techniques. However, the structural analysis revealed rhombohedral (hematite), and (magnetite) crystal structures in the materials synthesized at different temperature and durations, with particles ranged in size from 12 to 97 nm. More importantly, the magnetic characterization, performed with a vibrating sample magnetometer and SQUID magnetometer, indicated that the NPs showed not clear superparamagnetic behavior. In conclusion, this work demonstrates the synthesis of FeONPs with controlled size, shape and phase using microemulsion hydrothermal technique, with detailed characterization offering valuable insights into their magnetic and structural properties.

Renal Clearable Chiral Manganese Oxide Supraparticles for In Vivo Detection of Metalloproteinase-9 in Early Cancer Diagnosis

In this study, polypeptide TGGGPLGVARGKGGC-induced chiral manganese dioxide supraparticles (MnO2 SPs) are prepared for sensitive quantification of matrix metalloproteinase-9 (MMP-9) in vitro and in vivo. The results show that L-type manganese dioxide supraparticles (L-MnO2 SPs) exhibited twice the affinity for the cancer cell membrane receptor CD47 (cluster of differentiation, integrin-associated protein) than D-type manganese dioxide supraparticles (D-MnO2 SPs) to accumulate at the tumor site after surface modification of the internalizing arginine-glycine-aspartic acid (iRGD) ligand, specifically reacting with the MMP-9, disassembling into ultrasmall nanoparticles (NPs), and efficiently underwent renal clearance. Furthermore, L-MnO2 facilitates the quantification of MMP-9 in mouse tumor xenografts, as demonstrated by circular dichroism (CD) and magnetic resonance imaging (MRI) within 2 h. A strong linear relationship is observed between MMP-9 concentration and both CD and MRI intensity, ranging from 0.01 to 10 ng mL-1. The corresponding limits of detection (LOD) are 0.0054 ng mL-1 for CD and 0.0062 ng mL-1 for MRI, respectively. hese SPs provide a new approach for exploring chiral advanced biosensors for early diagnosis of cancer.

Multiscale Mass Transport Across Membranes: From Molecular Scale to Nanoscale to Micron Scale

Multiscale mass transport across membranes occurs ubiquitously in biological systems but is difficult to achieve and long-sought-after in abiotic systems. The multiscale transmembrane transport in abiotic systems requires the integration of multiscale transport channels and energy ergodicity, making multiscale mass transport a significant challenge. Herein, emulsion droplets with cell-like confinement are used as the experimental model, and multiscale mass transport is achieved from molecular scale to nanoscale to micron scale, reproducing rudimentary forms of cell-like transport behaviors. By adjustment of the magnetic dipole interactions between adjacent superparamagnetic nanoparticles (MNPs), the assembled structure at the interface of emulsion droplets is successfully modified, which constructs transport channels of various scales at the interface. Simultaneously, the assembly process of MNPs induces self-emulsification, which increases entropy and further reduces Gibbs free energy, ultimately realizing multiscale mass transport that evolves in time visiting all possible microscopic states (energy ergodicity). This work represents the comprehensive identification and realization of a multiscale transmembrane transport in abiotic droplet systems, which offers opportunities for the development of high-order cell-like characteristics in emulsion droplet-based communities, synthetic cells, microrobots, and drug carriers.

Magnetically induced localized heating enabling rapid and efficient synthesis of metal-organic frameworks

We demonstrate magnetic induction heating (MIH) with superparamagnetic iron oxide nanoparticles (IONPs) as a new rapid and energy-efficient methodology for synthesizing metal-organic frameworks (MOFs). Acting as localized heat sources, these IONPs overcome the energy losses associated with traditional solvothermal synthesis, which enables a fast, uniform, and highly energy-efficient heat transfer process. The versatility of this method is illustrated for the successful synthesis of three different benchmark MOFs in good yields with high crystallinity.

Terminal Tryptophan-Directed Anisotropic Self-Assembly for Precise Protein Nanostructure Regulation

A common challenge in nanotechnology is synthesizing nanomaterials with well-defined structures. In particular, it remains a major unresolved challenge to precisely regulate the structure and function of protein nanomaterials, which are structurally diverse, highly ordered, and complex and offer an innovative means that enables a high performance in various nanodevices, which is rarely achievable with other nanomaterials. Here an innovative approach is proposed to fabricating multi-dimensional (0- to 3D) protein nanostructures with functional and structural specialties via molecular-level regulation. This approach is based on a stable, consistent, anisotropic self-assembly of Tobacco mosaic virus (TMV) coat protein-derived engineered building blocks where genetically added tryptophan residues are externally tailored. The unique structural characteristics of each nanostructure above are demonstrated in detail through various analyses (electron microscopy, atomic force microscopy, dynamic light scattering, and small-angle X-ray scattering) and further investigated through molecular dynamics simulations, indicating that this control, anisotropic, and molecular assembly-based approach to regulating protein nanostructures holds great potential for customizing a variety of nanomaterials with unique functions and structures.

Electrified Dynamically Responsive Ammonia Decomposition to Hydrogen Based on Magnetic Heating of a Ru Nanocatalyst

Storing and transporting pressurized or liquid hydrogen is expensive and hazardous. As a result, safer methods, such as chemical storage in ammonia, are becoming increasingly important. However, the instantaneous start of a conventionally heated decomposition reactor is challenging. Here we report on the electrified and dynamically responsive decomposition of ammonia as a means of releasing on-demand chemically bonded hydrogen based on the rapid magnetic heating of a well-designed Ru-based nanocomposite catalyst. Under relatively mild conditions (400 °C, 1 bar) a rapid decomposition rate of 5.33 molNH3 gRu -1 h-1 was achieved. Experimental observations under non-isothermal, dynamic conditions coupled with modelling at the level of density functional theory and micro-kinetic modeling confirmed the minute-scale response of the H2 release. The rapid response of our catalytic system would, at least in principle, enable the utilization of intermittent, renewable electricity and a tunable H2/NH3 ratio in the reactor's effluent.

Structure-Function Relationship of Iron Oxide Nanoflowers: Optimal Sizes for Magnetic Hyperthermia Depending on Alternating Magnetic Field Conditions

Iron oxide nanoflowers (IONFs) that display singular magnetic properties can be synthesized through a polyol route first introduced almost 2 decades ago by Caruntu et al., presenting a multi-core morphology in which several grains (around 10 nm) are attached together and sintered. These outstanding properties are of great interest for magnetic field hyperthermia, which is considered as a promising therapy against cancer. Although of significantly smaller diameter, the specific adsorption rate (SAR) of IONFs reach values on the order of 1 kW g-1, as large as "magnetosomes" that are natural magnetic nanoparticles typically ~40 nm found in certain bacteria, which can be grown artificially but with much lower yield compared to chemical synthesis such as the polyol route. This work aims at better understanding the structure-property relationships, linking the internal IONF nanostructure as observed by high resolution transmission electron microscopy (HR-TEM) to their magnetic properties. A library of mono- and multicore IONFs is presented, with diameters ranging from 11 to 30 nm in a narrow size distribution. More particularly, by relating their structural features (diameter, morphology, defects…) to their magnetic properties investigated by utilizing AC magnetometry over a wide range of alternating magnetic field (AMF) conditions, we showed that the SAR values of all synthesized batches vary with overall diameter and number of constituting cores. These variations are in qualitative agreement with theoretical predictions either by the Linear Response Theory (LRT) at low fields or with the Stoner-Wohlfarth (SW) model at larger amplitudes, and with numerical simulations reported previously. More precisely, our results show a continuous (almost quadratic) increase of SAR with IONF diameter for AMF amplitudes of 20 kA m-1 and above, whatever the frequency between 146 and 344 kHz, and a pronounced maximum at an IONF diameter of 22 nm for amplitudes of 16 kA m-1 and below. Thank to this understanding of the impact of size and core multiplicity, stable colloidal solutions of IONPs can be synthesized with diameters targeting a SAR value adapted to the theragnostic approach envisioned.

Single-point mutated lanmodulin as a high-performance MRI contrast agent for vascular and kidney imaging

Magnetic resonance imaging contrast agents can enhance diagnostic precision but often face limitations such as short imaging windows, low tissue specificity, suboptimal contrast enhancement, or potential toxicity, which affect resolution and long-term monitoring. Here, we present a protein contrast agent based on lanmodulin, engineered with a single-point mutation at position 108 from N to D to yield maximum gadolinium binding sites. After loading with Gd3+ ions, the resulting protein complex, LanND-Gd, exhibits efficient renal clearance, high relaxivity, and prolonged renal retention compared to commercial agents. LanND-Gd enables high-performance visualization of whole-body structures and brain vasculature in male mice at a resolution finer than one hundred micrometers. In male ischemia mouse models, LanND-Gd also improves kidney dysfunction monitoring while minimizing risks of neural toxicity or immunogenic reactions. This protein-based contrast agent offers superior image quality, improved biocompatibility, and extended imaging timeframes, promising significant advancements in magnetic resonance-based diagnostics and patient outcomes.

Reductive pathways in molten inorganic salts enable colloidal synthesis of III-V semiconductor nanocrystals

Colloidal quantum dots, with their size-tunable optoelectronic properties and scalable synthesis, enable applications in which inexpensive high-performance semiconductors are needed. Synthesis science breakthroughs have been key to the realization of quantum dot technologies, but important group III-group V semiconductors, including colloidal gallium arsenide (GaAs), still cannot be synthesized with existing approaches. The high-temperature molten salt colloidal synthesis introduced in this work enables the preparation of previously intractable colloidal materials. We directly nucleated and grew colloidal quantum dots in molten inorganic salts by harnessing molten salt redox chemistry and using surfactant additives for nanocrystal shape control. Synthesis temperatures above 425°C are critical for realizing photoluminescent GaAs quantum dots, which emphasizes the importance of high temperatures enabled by molten salt solvents. We generalize the methodology and demonstrate nearly a dozen III-V solid-solution nanocrystal compositions that have not been previously reported.

Synthesis of a novel nanomagnetic N4 bis schiff base complex of copper(ii) as an efficient catalyst for click synthesis of tetrazoles

In this study, we have prepared a novel bis-Schiff-base copper(ii) complex by modifying Fe3O4 with acetylacetone functionalities and subsequently forming a Schiff base with 2-picolylamine and CuCl2 through a template method. Immobilization of 2,4-pentanedione and its reaction with 2-picolylamine enabled the synthesis of 1,3-diketimines (HNacNac) as an anionic ligand. This unique design resulted in a tetradentate N4 coordination sphere for copper(ii) ion complexation. The resulting heterogeneous catalyst, [Fe3O4@Sil-Schiff-base-Cu(ii)], efficiently catalyzed the click condensation of diverse aryl nitriles with sodium azide to produce 5-substituted 1H-tetrazoles in high yields and selectivity. The catalyst demonstrated remarkable stability and recyclability without appreciable loss of catalytic activity, as confirmed by hot filtration and reusability studies.

Anomalous size dependence of the coercivity of nanopatterned CrGeTe3

The coercivity of single-domain magnetic nanoparticles typically decreases with the nanoparticle size and reaches zero when thermal fluctuations overcome the magnetic anisotropy. Here, we used SQUID-on-tip microscopy to investigate the coercivity of square-shaped CrGeTe3 nanoislands with a wide range of sizes and width-to-thickness aspect ratios. The results reveal an anomalous size-dependent coercivity, with smaller islands exhibiting higher coercivity. The nonconventional scaling of the coercivity in CrGeTe3 nanoislands was found to be inversely proportional to the island width and thickness (1/wd). This scaling implies that the nanoisland magnetic anisotropy is proportional to the perimeter rather than the volume, suggesting a magnetic edge state. In addition, we observe that 1600 nm wide islands display multi-domain structures with zero net remnant field, corresponding to the magnetic properties of pristine CrGeTe3 flakes. Our findings highlight the significant influence of edge states on the magnetic properties of CrGeTe3 and deepen our understanding of low-dimensional magnetic systems.

Enhanced Magnetic Heating for Efficient Oxygen Evolution Reaction by Pinning Effect of Ferromagnetic/Antiferromagnetic Coupling

The magnetic heating effect under alternating magnetic fields (AMFs) has recently gained attention in catalysis due to its potential to greatly boost catalytic activities by providing localized heating around magnetic nanoparticles. However, nanoparticles still suffer from low magnetic heating efficiency due to their low magnetic anisotropy and thermal fluctuation, which is a key barrier in the wide application of AMF-assisted catalysis. Herein, by introducing the pinning effect of ferromagnetic/antiferromagnetic (FM/AFM) coupling, NiO/NiOOH (AFM/FM) core-shell nanoparticles exhibit significantly enhanced oxygen evolution reaction activity and resistance to thermal fluctuations under AMF, compared to NiOOH nanoparticles. Notably, magnetized NiO/NiOOH nanoparticles provide an overpotential of 186 mV at 10 mA cm-2, outperforming unmagnetized ones (218 mV) under the same conditions, further emphasizing the prominent role of the pinning effect in enhanced magnetic heating efficiency. This work provides valuable inspiration to design advanced magnetic catalysts and meet the challenge of the development of AMF-assisted catalysis.

Magnetic engineering nanoparticles: Versatile tools revolutionizing biomedical applications

The use of nanoparticles has increased significantly over the past few years in a number of fields, including diagnostics, biomedicine, environmental remediation, and water treatment, generating public interest. Among various types of nanoparticles, magnetic nanoparticles (MNPs) have emerged as an essential tool for biomedical applications due to their distinct physicochemical properties compared to other nanoparticles. This review article focuses on the recent growth of MNPs and comprehensively reviews the advantages, multifunctional approaches, biomedical applications, and latest research on MNPs employed in various biomedical techniques. Biomedical applications of MNPs hold on to their ability to rapidly switch magnetic states under an external field at room temperature. Ideally, these MNPs should be highly susceptible to magnetization when the field is applied and then lose that magnetization just as quickly once the field is removed. This unique property allows MNPs to generate heat when exposed to high-frequency magnetic fields, making them valuable tools in developing treatments for hyperthermia and other heat-related illnesses. This review underscores the role of MNPs as tools that hold immense promise in transforming various aspects of healthcare, from diagnostics and imaging to therapeutic treatments, with discussion on a wide range of peer-reviewed articles published on the subject. At the conclusion of this work, challenges and potential future advances of MNPs in the biomedical field are highlighted.

Designing intelligent bioorthogonal nanozymes: Recent advances of stimuli-responsive catalytic systems for biomedical applications

Bioorthogonal nanozymes have emerged as a potent tool in biomedicine due to their unique ability to perform enzymatic reactions that do not interfere with native biochemical processes. The integration of stimuli-responsive mechanisms into these nanozymes has further expanded their potential, allowing for controlled activation and targeted delivery. As such, intelligent bioorthogonal nanozymes have received more and more attention in developing therapeutic approaches. This review provides a comprehensive overview of the recent advances in the development and application of stimuli-responsive bioorthogonal nanozymes. By summarizing the design outlines for anchoring bioorthogonal nanozymes with stimuli-responsive capability, this review seeks to offer valuable insights and guidance for the rational design of these remarkable materials. This review highlights the significant progress made in this exciting field with different types of stimuli and the various applications. Additionally, it also examines the current challenges and limitations in the design, synthesis, and application of these systems, and proposes potential solutions and research directions. This review aims to stimulate further research toward the development of more efficient and versatile stimuli-responsive bioorthogonal nanozymes for biomedical applications.

Single-domain magnetic particles with motion behavior under electromagnetic AC and DC fields are a fatal cargo in Metropolitan Mexico City pediatric and young adult early Alzheimer, Parkinson, frontotemporal lobar degeneration and amyotrophic lateral sclerosis and in ALS patients

Metropolitan Mexico City (MMC) children and young adults exhibit overlapping Alzheimer and Parkinsons' diseases (AD, PD) and TAR DNA-binding protein 43 pathology with magnetic ultrafine particulate matter (UFPM) and industrial nanoparticles (NPs). We studied magnetophoresis, electron microscopy and energy-dispersive X-ray spectrometry in 203 brain samples from 14 children, 27 adults, and 27 ALS cases/controls. Saturation isothermal remanent magnetization (SIRM), capturing magnetically unstable FeNPs ~ 20nm, was higher in caudate, thalamus, hippocampus, putamen, and motor regions with subcortical vs. cortical higher SIRM in MMC ≤ 40y. Motion behavior was associated with magnetic exposures 25-100 mT and children exhibited IRM saturated curves at 50-300 mT associated to change in NPs position and/or orientation in situ. Targeted magnetic profiles moving under AC/AD magnetic fields could distinguish ALS vs. controls. Motor neuron magnetic NPs accumulation potentially interferes with action potentials, ion channels, nuclear pores and enhances the membrane insertion process when coated with lipopolysaccharides. TEM and EDX showed 7-20 nm NP Fe, Ti, Co, Ni, V, Hg, W, Al, Zn, Ag, Si, S, Br, Ce, La, and Pr in abnormal neural and vascular organelles. Brain accumulation of magnetic unstable particles start in childhood and cytotoxic, hyperthermia, free radical formation, and NPs motion associated to 30-50 μT (DC magnetic fields) are critical given ubiquitous electric and magnetic fields exposures could induce motion behavior and neural damage. Magnetic UFPM/NPs are a fatal brain cargo in children's brains, and a preventable AD, PD, FTLD, ALS environmental threat. Billions of people are at risk. We are clearly poisoning ourselves.

Directed assembly of small binary clusters of magnetizable ellipsoids

We report the effect of shape anisotropy and material properties on the directed assembly of binary suspensions composed of magnetizable ellipsoids. In a Monte Carlo simulation, we implement the ellipsoid-dipole model to calculate the pairwise dipolar interaction energy as a function of position and orientation. The analysis explores dilute suspensions of paramagnetic and diamagnetic ellipsoids with different aspect ratios in a superparamagnetic medium. We analyze the local order of binary structures as a function of particle aspect ratio, medium permeability, and dipolar interaction strength. Our results show that local order and symmetry are tunable under the influence of a uniform magnetic field when one component of the structure is dilute with respect to the other. The simulation results match previously reported experiments on the directed assembly of binary suspension of spheres. Additionally, we report the conditions on particle aspect ratios and medium properties for various structures with rotational symmetries, as well as open and enclosed structures under the influence of a uniform magnetic field.

Functionalized magnetic particles coupled with LC-MS strategy facilitated discovery of trace thioalkaloids with potent immunosuppressive activity

Trace natural products (TNPs) are still the vital source of drug development. However, the mining of novel TNPs is becoming increasingly challenging due to their low abundance and complex interference. A comprehensive strategy was proposed in which the functionalized magnetic particles integrated with LC-MS for TNPs discovery. Under the guidance of the approach, fifteen trace Nuphar alkaloids including seven new ones, cyanopumiline A sulfoxide (1), cyanopumiline C sulfoxide (8) and cyanopumilines A-E (4-5, 10, 12-13) featuring an undescribed nitrile-containing 6/6/5/6/6 pentacyclic ring system were isolated from the rhizomes of Nuphar pumila. Their structures and absolute configurations were determined on the basis of detailed spectroscopic data analysis and single-crystal X-ray diffraction analysis. Notably, a concise method based on 13C NMR spectroscopy was established to determine the relative configurations of spiroatoms. Biologically, compounds 1-12 exhibited potent immunosuppressive activities with IC50 values ranging from 0.1-12.1 μM against anti-CD3/CD28 induced human peripheral T cell proliferation. Mechanistic studies revealed that 4 could dose-dependently decrease pro-inflammatory cytokines and the expression levels of CD25 and CD71.

Polymeric nanocarrier-based adjuvants to enhance a locally produced mucosal coryza vaccine in chicken

Infectious coryza (IC) is an acute upper respiratory disease of chicken caused by Avibacterium (A.) paragallinarum. This disease results in an increased culling rate in meat chicken and a marked decrease in egg production (10% to more than 40%) in laying and breeding hens. Vaccines were first used against IC and effectively controlled the disease. Nanotechnology provides an excellent way to develop a new generation of vaccines. NPs have been widely used in vaccine design as adjuvants and antigen delivery vehicles and as antibacterial agents; thus, they can be used as inactivators for bacterial culture. In this research, the antibacterial effects of several nanoparticles (NPs), such as silicon dioxide with chitosan (SiO2-CS), oleoyl-chitosan (O.CS), silicon dioxide (SiO2), and iron oxide (Fe3O4), on A. paragallinarum were studied. Additionally, different A. paragallinarum vaccines were made using the same nanomaterials at a concentration of 400 µg/ml to help control infectious coryza disease in chicken. A concentration of 400 µg/ml of all the NPs tested was the best concentration for the inactivation of A. paragallinarum. Additionally, this study showed that the infectious coryza vaccine adjuvanted with SiO2 NPs had the highest immune response, followed by the infectious coryza vaccine adjuvanted with Fe3O4 NPs, the infectious coryza vaccine adjuvanted with SiO2-CS NPs, and the infectious coryza vaccine adjuvanted with O.CS NPs in comparison with the infectious coryza vaccine adjuvanted with liquid paraffin (a commercial vaccine).

Room-temperature-persistent magnetic interaction between coordination complexes and nanoparticles in maghemite-based nanohybrids

Maghemite nanoparticles functionalised with Co(II) coordination complexes at their surface show a significant increase of their magnetic anisotropy, leading to a doubling of the blocking temperature and a sixfold increase of the coercive field. Magnetometric studies suggest an enhancement that is not related to surface disordering, and point to a molecular effect involving magnetic exchange interactions mediated by the oxygen atoms at the interface as its source. Field- and temperature-dependent X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) studies show that the magnetic anisotropy enhancement is not limited to surface atoms and involves the core of the nanoparticle. These studies also point to a mechanism driven by anisotropic exchange and confirm the strength of the magnetic exchange interactions. The coupling between the complex and the nanoparticle persists at room temperature. Simulations based on the XMCD data give an effective exchange field value through the oxido coordination bridge between the Co(II) complex and the nanoparticle that is comparable to the exchange field between iron ions in bulk maghemite. Further evidence of the effectiveness of the oxido coordination bridge in mediating the magnetic interaction at the interface is given with the Ni(II) analog to the Co(II) surface-functionalised nanoparticles. A substrate-induced magnetic response is observed for the Ni(II) complexes, up to room temperature.

Tumor-Homing Peptides as Crucial Component of Magnetic-Based Delivery Systems: Recent Developments and Pharmacoeconomical Perspective

According to data from the World Health Organization (WHO), cancer is considered to be one of the leading causes of death worldwide, and new therapeutic approaches, especially improved novel cancer treatment regimens, are in high demand. Considering that many chemotherapeutic drugs tend to have poor pharmacokinetic profiles, including rapid clearance and limited on-site accumulation, a combined approach with tumor-homing peptide (THP)-functionalized magnetic nanoparticles could lead to remarkable improvements. This is confirmed by an increasing number of papers in this field, showing that the on-target peptide functionalization of magnetic nanoparticles improves their penetration properties and ensures tumor-specific binding, which results in an increased clinical response. This review aims to highlight the potential applications of THPs in combination with magnetic carriers across various fields, including a pharmacoeconomic perspective.

Magneto-optical nanosystems for tumor multimodal imaging and therapy in-vivo

Multimodal imaging, which combines the strengths of two or more imaging modalities to provide complementary anatomical and molecular information, has emerged as a robust technology for enhancing diagnostic sensitivity and accuracy, as well as improving treatment monitoring. Moreover, the application of multimodal imaging in guiding precision tumor treatment can prevent under- or over-treatment, thereby maximizing the benefits for tumor patients. In recent years, several intriguing magneto-optical nanosystems with both magnetic and optical properties have been developed, leading to significant breakthroughs in the field of multimodal imaging and image-guided tumor therapy. These advancements pave the way for precise tumor medicine. This review summarizes various types of magneto-optical nanosystems developed recently and describes their applications as probes for multimodal imaging and agents for image-guided therapeutic interventions. Finally, future research and development prospects of magneto-optical nanosystems are discussed along with an outlook on their further applications in the biomedical field.

Magnetic Iron Oxide Nanoparticles Coated by Coumarin-Bound Copolymer for Enhanced Magneto- and Photothermal Heating and Luminescent Thermometry

In this work, we report on the synthesis and investigation of new hybrid multifunctional iron oxide nanoparticles (IONPs) coated by coumarin-bound copolymer, which combine magneto- or photothermal heating with luminescent thermometry. A series of amphiphilic block copolymers, including Coum-C11-PPhOx27-PMOx59 and Coum-C11-PButOx8-PMOx42 bearing luminescent and photodimerizable coumarin moiety, as well as coumarin-free PPhOx27-PMOx57, were evaluated for their utility as luminescent thermometers and for encapsulating spherical 26 nm IONPs. The obtained IONP@Coum-C11-PPhOx27-PMOx59 nano-objects are perfectly dispersible in water and able to provide macroscopic heating remotely triggered by an alternating current magnetic field (AMF) with a specific absorption rate (SAR) value of 240 W.g-1 or laser irradiation with a photothermal conversion efficiency of η = 68%. On the other hand, they exhibit temperature-dependent emission of coumarin offering the function of luminescent thermometer, which operates in the visible region between 20 °C and 60 °C in water displaying a maximal relative thermal sensitivity (Sr) of 1.53%·°C-1 at 60 °C.

Development of dispersive solid phase extraction based on magnetic metal organic framework for the extraction of sunitinib in biological samples and its determination by high performance liquid chromatography-tandem mass spectrometry

Herein, a simple, sensitive, and reliable dispersive solid phase extraction was reported for the efficient extraction of sunitinib from biological samples. To facilitate the extraction of the desired analyte from urine and plasma samples, magnetic MIL-101Cr (NH2) @SiO2 @ NiFe2O4 was synthesized by a hydrothermal method and applied as an effective sorbent during the extraction process. After adsorption of the drug using 10 mg of MIL-101Cr (NH2) @ SiO2 @ NiFe2O4 nanoparticles through vortexing (1 min), the sorbent was separatedfrom the sample solution using a magnet. To eluate the drug, the sorbent containing the sunitinib was contacted with 100 µL dimethylformamide. The eluent was analyzed by high performance liquid chromatography-tandem mass spectrometry. Reasonable validation data consisting of low limits of detection (0.14, 0.35, and 0.70 ng mL-1 in deionized water, plasma, and urine) and quantification (0.48, 1.2, and 2.4 ng mL-1 in deionized water, plasma, and urine, respectively), a wide linear range of the calibration curve (0.48-200, 1.2-200, and 2.4-100 ng mL-1 in deionized water, plasma, and urine, respectively) good extraction recovery (76 %), and low relative standard deviations for inter- and intra-day precisions (6.9 %) were obtained by the method. Eventually, the proposed procedure was effectively implemented on both plasma and urine samples, yielding successful outcomes.

Economic and Accessible Portable Homemade Magnetic Hyperthermia System: Influence of the Shape, Characteristics and Type of Nanoparticles in Its Effectiveness

Currently, one of the main causes of death in the world is cancer; therefore, it is urgent to obtain a precocious diagnosis, as well as boost research and development of new potential treatments, which should be more efficient and much less invasive for the patient. Magnetic hyperthermia (MH) is an emerging cancer therapy using nanoparticles, which has proved to be effective when combined with chemotherapy, radiotherapy and/or surgery, or even by itself, depending on the type and location of the tumor's cells. This article presents the results obtained by using a previously developed economic homemade hyperthermia device with different types of magnetite nanoparticles, with sizes ranging between 12 ± 5 and 36 ± 11 nm and presenting different shapes (spherical and cubic particles). These magnetic nanoparticles (MNPs) were synthesized by three different methods (co-precipitation, solvothermal and hydrothermal processes), with their final form being naked, or possessing different kinds of covering layers (polyethylene glycol (PEG) or citric acid (CA)). The parameters used to characterize the heating by magnetic hyperthermia, namely the Specific Absorption Rate (SAR) and the intrinsic loss power (ILP), have been obtained by two different methods. Among other results, these experiments allowed for the determination of which synthesized MNPs showed the best performance concerning hyperthermia. From the results, it may be concluded that, as expected, the shape of MNPs is an important factor, as well as the time that the MNPs can remain suspended in solution (which is directly related to the concentration and covering layer of the MNPs). The MNPs that gave the best results in terms of the SAR were the cubic particles covered with PEG, while in terms of total heating the spherical particles covered with citric acid proved to be better.

Tumor versus Tumor Cell Targeting in Metal-Based Nanoparticles for Cancer Theranostics

The application of metal-based nanoparticles (mNPs) in cancer therapy and diagnostics (theranostics) has been a hot research topic since the early days of nanotechnology, becoming even more relevant in recent years. However, the clinical translation of this technology has been notably poor, with one of the main reasons being a lack of understanding of the disease and conceptual errors in the design of mNPs. Strikingly, throughout the reported studies to date on in vivo experiments, the concepts of "tumor targeting" and "tumor cell targeting" are often intertwined, particularly in the context of active targeting. These misconceptions may lead to design flaws, resulting in failed theranostic strategies. In the context of mNPs, tumor targeting can be described as the process by which mNPs reach the tumor mass (as a tissue), while tumor cell targeting refers to the specific interaction of mNPs with tumor cells once they have reached the tumor tissue. In this review, we conduct a critical analysis of key challenges that must be addressed for the successful targeting of either tumor tissue or cancer cells within the tumor tissue. Additionally, we explore essential features necessary for the smart design of theranostic mNPs, where 'smart design' refers to the process involving advanced consideration of the physicochemical features of the mNPs, targeting motifs, and physiological barriers that must be overcome for successful tumor targeting and/or tumor cell targeting.

Tuning Surface, Phase, and Magnetization of Superparamagnetic Magnetite by Ionic Liquids: Single-Step Microwave-Assisted Synthesis

Achieving colloidal and chemical stability in ferrofluids by surface modification requires multiple steps, including purification, ex situ modification steps, and operation at high temperatures. In this study, a single-step microwave-assisted methodology is developed for iron oxide nanoparticle (IONP) synthesis utilizing a series of imidazolium-based ionic liquids (ILs) with chloride, bis(trifluoromethylsulfonyl)imide, and pyrrolide anions as the reaction media, thus eliminating the use of volatile organics while enabling rapid synthesis at 80 °C as well as in situ surface functionalization. The characterized surface functionality, hydrodynamic particle size, magnetization, and colloidal stability of the IONPs demonstrate a strong dependence on the IL structure, ion coordination strength, reactivity, and hydrophilicity. The IONPs present primarily a magnetite (Fe3O4) phase with superparamagnetism with the highest saturation magnetization at 81 and 73 emu/g at 10 and 300 K, respectively. Depending on the IL coating, magnetization and exchange anisotropy decrease by 20 and 2-3 emu/g (at 35 wt % IL), respectively, but still represent the highest magnetization achieved for coated IONPs by a coprecipitation method. Further, the surface-functionalized superparamagnetic magnetite nanoparticles show good dispersibility and colloidal stability in water and dimethyl sulfoxide at 0.1 mg/mL concentration over the examined 3 month period. This study reports on the intermolecular and chemical interactions between the particle surface and the ILs under synthetic conditions as they relate to the magnetic and thermal properties of the resulting IONPs that are well suited for a variety of applications, including separation and catalysis.

Anisotropy in magnetic materials for sensors and actuators in soft robotic systems

The field of soft intelligent robots has rapidly developed, revealing extensive potential of these robots for real-world applications. By mimicking the dexterities of organisms, robots can handle delicate objects, access remote areas, and provide valuable feedback on their interactions with different environments. For autonomous manipulation of soft robots, which exhibit nonlinear behaviors and infinite degrees of freedom in transformation, innovative control systems integrating flexible and highly compliant sensors should be developed. Accordingly, sensor-actuator feedback systems are a key strategy for precisely controlling robotic motions. The introduction of material magnetism into soft robotics offers significant advantages in the remote manipulation of robotic operations, including touch or touchless detection of dynamically changing shapes and positions resulting from the actuations of robots. Notably, the anisotropies in the magnetic nanomaterials facilitate the perception and response with highly selective, directional, and efficient ways used for both sensors and actuators. Accordingly, this review provides a comprehensive understanding of the origins of magnetic anisotropy from both intrinsic and extrinsic factors and summarizes diverse magnetic materials with enhanced anisotropy. Recent developments in the design of flexible sensors and soft actuators based on the principle of magnetic anisotropy are outlined, specifically focusing on their applicabilities in soft robotic systems. Finally, this review addresses current challenges in the integration of sensors and actuators into soft robots and offers promising solutions that will enable the advancement of intelligent soft robots capable of efficiently executing complex tasks relevant to our daily lives.

Recent Advances in Synergistic Effect of Nanoparticles and Its Biomedical Application

The synergistic impact of nanomaterials is critical for novel intracellular and/or subcellular drug delivery systems of minimal toxicity. This synergism results in a fundamental bio/nano interface interaction, which is discussed in terms of nanoparticle translocation, outer wrapping, embedding, and interior cellular attachment. The morphology, size, surface area, ligand chemistry and charge of nanoparticles all play a role in translocation. In this review, we suggest a generalized mechanism to characterize the bio/nano interface, as we discuss the synergistic interaction between nanoparticles and cells, tissues, and other biological systems. Novel perceptions are reviewed regarding the ability of nanoparticles to improve hybrid nanocarriers with homogeneous structures to enhance multifunctional biomedical applications, such as bioimaging, tissue engineering, immunotherapy, and phototherapy.

Metal-Organic Framework as a New Type of Magnetothermally-Triggered On-Demand Release Carrier

The development of external stimuli-controlled payload systems has been sought after with increasing interest toward magnetothermally-triggered drug release (MTDR) carriers due to their non-invasive features. However, current MTDR carriers present several limitations, such as poor heating efficiency caused by the aggregation of iron oxide nanoparticles (IONPs) or the presence of antiferromagnetic phases which affect their efficiency. Herein, a novel MTDR carrier is developed using a controlled encapsulation method that fully fixes and confines IONPs of various sizes within the metal-organic frameworks (MOFs). This novel carrier preserves the MOF's morphology, porosity, and IONP segregation, while enhances heating efficiency through the oxidation of antiferromagnetic phases in IONPs during encapsulation. It also features a magnetothermally-responsive nanobrush that is stimulated by an alternating magnetic field to enable on-demand drug release. The novel carrier shows improved heating, which has potential applications as contrast agents and for combined chemo and magnetic hyperthermia therapy. It holds a great promise for magneto-thermally modulated drug dosing at tumor sites, making it an exciting avenue for cancer treatment.

Magnetic aerogels from FePt and CoPt3 directly from organic solution

Here the synthesis of magnetic aerogels from iron platinum and cobalt platinum nanoparticles is presented. The use of hydrazine monohydrate as destabilizing agent triggers the gelation directly from organic solution, and therefore a phase transfer to aqueous media prior to the gelation is not necessary. The aerogels were characterized through Transmission Electron Microscopy, Scanning Electron Microscopy, Powder X-Ray Diffraction Analysis and Argon Physisorption measurements to prove the formation of a porous network and define their compositions. Additionally, magnetization measurements in terms of hysteresis cycles at 5 K and 300 K (M-H-curves) as well as zero field cooled-field cooled measurements (ZFC-FC measurements) of the dried colloids and the respective xero- and aerogels were performed, in order to analyze the influence of the gelation process and the network structure on the magnetic properties.

Multiparametric modulation of magnetic transduction for biomolecular sensing in liquids

The recent COVID19 pandemic has remarkably boosted the research on in vitro diagnosis assays to detect biomarkers in biological fluids. Specificity and sensitivity are mandatory for diagnostic kits aiming to reach clinical stages. Whilst the modulation of sensitivity can significantly improve the detection of biomarkers in liquids, this has been scarcely explored. Here, we report on the proof of concept and parametrization of a novel biosensing methodology based on the changes of AC magnetic hysteresis areas observed for magnetic nanoparticles following biomolecular recognition in liquids. Several parameters are shown to significantly modulate the transducing capacity of magnetic nanoparticles to detect analytes dispersed in saline buffer at concentrations of clinical relevance. Magnetic nanoparticles were bio-conjugated with an engineered recognition peptide as a receptor. Analytes are engineered tetratricopeptide binding domains fused to the fluorescent protein whose dimerization state allows mono- or divalent variants. Our results unveil that the number of receptors per particle, analyte valency and concentration, nanoparticle composition and concentration, and field conditions play a key role in the formation of assemblies driven by biomolecular recognition. Consequently, all these parameters modulate the nanoparticle transduction capacity. Our study provides essential insights into the potential of AC magnetometry for customizing biomarker detection in liquids.

Highly anisotropic Fe3C microflakes constructed by solid-state phase transformation for efficient microwave absorption

Soft magnetic materials with flake geometry can provide shape anisotropy for breaking the Snoek limit, which is promising for achieving high-frequency ferromagnetic resonances and microwave absorption properties. Here, two-dimensional (2D) Fe3C microflakes with crystal orientation are obtained by solid-state phase transformation assisted by electrochemical dealloying. The shape anisotropy can be further regulated by manipulating the thickness of 2D Fe3C microflakes under different isothermally quenching temperatures. Thus, the resonant frequency is adjusted effectively from 9.47 and 11.56 GHz under isothermal quenching from 700 °C to 550 °C. The imaginary part of the complex permeability can reach 0.9 at 11.56 GHz, and the minimum reflection loss (RLmin) is -52.09 dB (15.85 GHz, 2.90 mm) with an effective absorption bandwidth (EAB≤-10 dB) of 2.55 GHz. This study provides insight into the preparation of high-frequency magnetic loss materials for obtaining high-performance microwave absorbers and achieves the preparation of functional materials from traditional structural materials.

Dual-responsive magnetic nanodroplets for controlled oxygen release via ultrasound and magnetic stimulation

Magnetic oxygen-loaded nanodroplets (MOLNDs) are a promising class of nanomaterials dually sensitive to ultrasound and magnetic fields, which can be employed as nanovectors for drug delivery applications, particularly in the field of hypoxic tissue treatment. Previous investigations were primarily focused on the application of these hybrid systems for hyperthermia treatment, exploiting magnetic nanoparticles for heat generation and nanodroplets as carriers and ultrasound contrast agents for treatment progress monitoring. This work places its emphasis on the prospect of obtaining an oxygen delivery system that can be activated by both ultrasound and magnetic fields. To achieve this goal, Fe3O4 nanoparticles were employed to decorate and induce the magnetic vaporization of OLNDs, allowing oxygen release. We present an optimized method for preparing MOLNDs by decorating nanodroplets made of diverse fluorocarbon cores and polymeric coatings. Furthermore, we performed a series of characterizations for better understanding how magnetic decoration can influence the physicochemical properties of OLNDs. Our comprehensive analysis demonstrates the efficacy of magnetic stimulation in promoting oxygen release compared to conventional ultrasound-based methods. We emphasize the critical role of selecting the appropriate fluorocarbon core and polymeric coating to optimize the decoration process and enhance the oxygen release performance of MOLNDs.

Materials-Driven Soft Wearable Bioelectronics for Connected Healthcare

In the era of Internet-of-things, many things can stay connected; however, biological systems, including those necessary for human health, remain unable to stay connected to the global Internet due to the lack of soft conformal biosensors. The fundamental challenge lies in the fact that electronics and biology are distinct and incompatible, as they are based on different materials via different functioning principles. In particular, the human body is soft and curvilinear, yet electronics are typically rigid and planar. Recent advances in materials and materials design have generated tremendous opportunities to design soft wearable bioelectronics, which may bridge the gap, enabling the ultimate dream of connected healthcare for anyone, anytime, and anywhere. We begin with a review of the historical development of healthcare, indicating the significant trend of connected healthcare. This is followed by the focal point of discussion about new materials and materials design, particularly low-dimensional nanomaterials. We summarize material types and their attributes for designing soft bioelectronic sensors; we also cover their synthesis and fabrication methods, including top-down, bottom-up, and their combined approaches. Next, we discuss the wearable energy challenges and progress made to date. In addition to front-end wearable devices, we also describe back-end machine learning algorithms, artificial intelligence, telecommunication, and software. Afterward, we describe the integration of soft wearable bioelectronic systems which have been applied in various testbeds in real-world settings, including laboratories that are preclinical and clinical environments. Finally, we narrate the remaining challenges and opportunities in conjunction with our perspectives.

Interplay of Anisotropy Energy Barrier and Self-Heating Efficiency of Cobalt-Substituted CuFe2O4 Nanoparticles

In this study, we delve into the intricate interplay between the anisotropy energy barrier and the self-heating efficiency of magnetic nanoparticles (MNPs). We embarked on this exploration by synthesizing Cu1-xCoxFe2O4 (x = 0, 0.1, 0.3, and 0.5) MNPs using a straightforward coprecipitation method. Our magnetic assessments, conducted at different temperatures, unveiled a notable trend as we traversed from x = 0.1 to x = 0.5. Specifically, we observed a consistent increase in saturation magnetization, coercivity, and remanence. This pattern also extended to the anisotropy energy barrier, which was derived from the effective anisotropy constant determined through the temperature dependency of the coercivity method. However, an intriguing twist emerged when we scrutinized the specific absorption rate (SAR), calculated via the Box-Lucas method. Contrary to much of the existing literature, our experimental results showcased a decline in SAR concerning x. This experimental work challenges the conventional understanding of the relationship between the anisotropy energy barrier and the SAR value of these nanoparticles. This study prompts us to reconsider the intricate mechanisms governing the relaxation of magnetic moments and subsequent heat release when subjected to an alternating magnetic field. By doing so, we aim to gain fresh insights into the self-heating properties of MNPs and optimize their utilization to better understand their heat-release properties and ensure that they are used as efficiently as possible in a variety of biomedical applications.

Chiral Plasmonic Hybrid Nanostructures: A Gateway to Advanced Chiroptical Materials

Chirality introduces a new dimension of functionality to materials, unlocking new possibilities across various fields. When integrated with plasmonic hybrid nanostructures, this attribute synergizes with plasmonic and other functionalities, resulting in unprecedented chiroptical materials that push the boundaries of the system's capabilities. Recent advancements have illuminated the remarkable chiral light-matter interactions within chiral plasmonic hybrid nanomaterials, allowing for the harnessing of their tunable optical activity and hybrid components. These advancements have led to applications in areas such as chiral sensing, catalysis, and spin optics. Despite these promising developments, there remains a need for a comprehensive synthesis of the current state-of-the-art knowledge, as well as a thorough understanding of the construction techniques and practical applications in this field. This review begins with an exploration of the origins of plasmonic chirality and an overview of the latest advancements in the synthesis of chiral plasmonic hybrid nanostructures. Furthermore, representative emerging categories of hybrid nanomaterials are classified and summarized, elucidating their versatile applications. Finally, the review engages with the fundamental challenges associated with chiral plasmonic hybrid nanostructures and offer insights into the future prospects of this advanced field.

Magnetic nanoagent assisted deciphering of heterogeneous glycans in extracellular vesicles of varied cellular origins

Extracellular vesicles bear a rich glycome that presents versatile functions in diverse biological processes. Leverage polydopamine modified magnetic particles to serve as nanosized agents for rapid and robust EV capture and manipulation, we here integrated the easy magnetic actuation with specific lectin-glycan binding and enzyme-mediated fluorescence amplification and thus proposed a facile approach to efficiently decipher a broad spectrum of glycans in EVs. Termed magnetic nanoagent assisted extracellular vesicle glycan deciphering (MAEG), the developed assay utilized a magnet as the assistant operation tool and realized fast (∼1 h) and sensitive (a limit of detection of ∼0.7 μg/mL vesicles) EV glycan analysis in a simple low-cost (around 2.27 Chinese Yuan for one test) manner without requirement of any sophisticated platforms. With robust performance for different sample species, the assay achieved to depict the comprehensive glycosylation landscapes for varied EVs derived from eight cell lines focusing on non-small-cell lung cancer. Systematic analyses clearly revealed the high heterogeneity in glycan features of EVs of varied cellular origins. Using an established difference network method, unique glycan features in different EVs were sifted out and further compiled to construct lectin-denoted patterns as dedicated glycosylation fingerprints, potentially expanding EV-based clinical applications.

Programming an Enhanced Uptake and the Intracellular Fate of Magnetic Microbeads

This study compares two kinds of magnetic microbeads with different surface features and cell entry pathways, aiming to provide insights into how to program their cell uptake and intracellular fate. It is found that a rougher surface enhances the cell uptake of the microbeads, regardless of whether they are pulled by a magnetic field gradient or adsorbed by the cell membrane. However, the entry route affects the intracellular localization of the microbeads: The magnetically dragged microbeads reach the cytoplasm, while the adsorbed microbeads stay in the late endosomes and lysosomes. This suggests that different strategies can be used to target different cellular compartments with magnetic microbeads. Moreover, it is demonstrated that the cells containing the microbeads can be moved and regrown at specific locations by applying a magnetic field gradient, showing the potential of these magnetic microbeads for cell delivery and manipulation.

A novel two-dimensional NiCl2O8 lattice with negative Poisson's ratio and magnetic modulation

Two-dimensional (2D) materials with simultaneous magnetic semiconducting properties and a negative Poisson's ratio are crucial for fabricating multifunctional electronic devices. However, progress in this area has been generally constrained. Based on first-principles calculations, we engineered a 2D Ni-based oxyhalide with a honeycomb lattice structure. It was observed that the NiCl2O8 monolayer exhibits both high- and low-buckling states in its geometry, along with intrinsic magnetic semiconductor properties in its electronic structure. Importantly, we demonstrated that the magnetic ordering of the NiCl2O8 lattice is susceptible to applied strain, which resulted in a phase transition from paramagnetic to ferromagnetic under biaxial strain. The Curie temperature was also evaluated using Monte Carlo simulations within the Ising model. Additionally, our research uncovered that the 2D NiCl2O8 lattice chain displays a negative Poisson's ratio (NPR) along the z-direction. The triangular hinge structure in its centrosymmetric configuration was identified as the origin of this unique phenomenon. The coexistence of NPR and magnetic phase transition properties in the NiCl2O8 lattice makes it quite promising for applications in nanoelectronic and spintronic devices.

Quantifying the Efficacy of Magnetic Nanoparticles for MRI and Hyperthermia Applications via Machine Learning Methods

Magnetic nanoparticles are a prospective class of materials for use in biomedicine as agents for magnetic resonance imagining (MRI) and hyperthermia treatment. However, synthesis of nanoparticles with high efficacy is resource-intensive experimental work. In turn, the use of machine learning (ML) methods is becoming useful in materials design and serves as a great approach to designing nanomagnets for biomedicine. In this work, for the first time, an ML-based approach is developed for the prediction of main parameters of material efficacy, i.e., specific absorption rate (SAR) for hyperthermia and r1 /r2 relaxivities in MRI, with parameters of nanoparticles as well as experimental conditions as descriptors. For that, a unique database with more than 980 magnetic nanoparticles collected from scientific articles is assembled. Using this data, several tree-based ensemble models are trained to predict SAR, r1 and r2 relaxivity. After hyperparameter optimization, models reach performances of R2 = 0.86, R2 = 0.78, and R2 = 0.75, respectively. Testing the models on samples unseen during the training shows no performance drops. Finally, DiMag, an open access resource created to guide synthesis of novel nanosized magnets for MRI and hyperthermia treatment with machine learning and boost development of new biomedical agents, is developed.

Design of Water-Soluble Rotaxane-Capped Superparamagnetic, Ultrasmall Fe3O4 Nanoparticles for Targeted NIR Fluorescence Imaging in Combination with Magnetic Resonance Imaging

Integrating an NIR fluorescent probe with a magnetic resonance imaging (MRI) agent to harvest complementary imaging information is challenging. Here, we have designed water-soluble, biocompatible, noncytotoxic, bright-NIR-emitting, sugar-functionalized, mechanically interlocked molecules (MIMs)-capped superparamagnetic ultrasmall Fe3O4 NPs for targeted multimodal imaging. Dual-functional stoppers containing an unsymmetrical NIR squaraine dye interlocked within a macrocycle to construct multifunctional MIMs are developed with enhanced NIR fluorescence efficiency and durability. One of the stoppers of the axle is composed of a lipophilic cationic TPP+ functionality to target mitochondria, and the other stopper comprises a dopamine-containing catechol group to anchor at the surface of the synthesized Fe3O4 NPs. Fe3O4 NPs surface-coated with targeted NIR rotaxanes help to deliver ultrasmall magnetic NPs specifically inside the mitochondria. Two carbohydrate moieties are conjugated with the macrocycle of the rotaxane via click chemistry to improve the water solubility of MitoSQRot-(Carb-OH)2-DOPA-Fe3O4 NPs. Water-soluble, rotaxane-capped Fe3O4 NPs are used for live-cell mitochondria-targeted NIR fluorescence confocal imaging, 3D and multicolor imaging in combination with T2-weighted MRI on a 9.4 T MR scanner with a high relaxation rate (r2) of 180.7 mM-1 s-1. Biocompatible, noncytotoxic, ultrabright NIR rotaxane-capped superparamagnetic ultrasmall monodisperse Fe3O4 NPs could be a promising agent for targeted multimodal imaging applications.

Nanoparticle-Based Photothermal Therapy for Breast Cancer Noninvasive Treatment

Rapid advancements in materials science and nanotechnology, intertwined with oncology, have positioned photothermal therapy (PTT) as a promising noninvasive treatment strategy for cancer. The breast's superficial anatomical location and aesthetic significance render breast cancer a particularly pertinent candidate for the clinical application of PTT following melanoma. This review comprehensively explores the research conducted on the various types of nanoparticles employed in PTT for breast cancer and elaborates on their specific roles and mechanisms of action. The integration of PTT with existing clinical therapies for breast cancer is scrutinized, underscoring its potential for synergistic outcomes. Additionally, the mechanisms underlying PTT and consequential modifications to the tumor microenvironment after treatment are elaborated from a medical perspective. Future research directions are suggested, with an emphasis on the development of integrative platforms that combine multiple therapeutic approaches and the optimization of nanoparticle synthesis for enhanced treatment efficacy. The goal is to push the boundaries of PTT toward a comprehensive, clinically applicable treatment for breast cancer.

Magnetically Induced Anisotropic Interaction in Colloidal Assembly

The wide accessibility to nanostructures with high uniformity and controllable sizes and morphologies provides great opportunities for creating complex superstructures with unique functionalities. Employing anisotropic nanostructures as the building blocks significantly enriches the superstructural phases, while their orientational control for obtaining long-range orders has remained a significant challenge. One solution is to introduce magnetic components into the anisotropic nanostructures to enable precise control of their orientations and positions in the superstructures by manipulating magnetic interactions. Recognizing the importance of magnetic anisotropy in colloidal assembly, we provide here an overview of magnetic field-guided self-assembly of magnetic nanoparticles with typical anisotropic shapes, including rods, cubes, plates, and peanuts. The Review starts with discussing the magnetic energy of nanoparticles, appreciating the vital roles of magneto-crystalline and shape anisotropies in determining the easy magnetization direction of the anisotropic nanostructures. It then introduces superstructures assembled from various magnetic building blocks and summarizes their unique properties and intriguing applications. It concludes with a discussion of remaining challenges and an outlook of future research opportunities that the magnetic assembly strategy may offer for colloidal assembly.

Quantifying superparamagnetic signatures in nanoparticle magnetite: a generalized approach for physically meaningful statistics and synthesis diagnostics

Magnetization is a common measurable for characterizing bulk, nanoscale, and molecular materials, which can be quantified to high precision as a function of an applied external field. These data provide detailed information about a material's electronic structure, phase purity, and impurities, though interpreting this data can be challenging due to many contributing factors. In sub-single-domain particles of a magnetic material, an inherently time-dependent rotation of the entire particle spin becomes possible. This phenomenon, known as superparamagnetism (SPM), simultaneously represents a very early size-dependent property to be considered, while being one of the least explored in the current quantum materials era. This discrepancy is, at least in part, due to the need for models with less built-in complexity that can facilitate the generation of comparative data. In this work, we map an extensive dataset of variable-size SPM Fe₃O₄ (magnetite) to an intrinsic statistical model for their field-dependence. By constraining the SPM behavior to a probabilistic model, the data are apportioned to several decorrelated sources. From this, there is strong evidence that standard measures such as saturation magnetization, M_S, are poor comparative parameters, being dependent on experimental knowledge and measurement of the magnetic mass. In contrast, parameters of the intrinsic probability distribution, such as the maximum susceptibility, χ_max, are far better suited to describe the SPM behavior itself and do not propagate unknown magnetic mass error. By confining the data fitting to intrinsic variables of the model distribution, scaling parameters, and linear contributions, we find greater value in magnetic data, ultimately aiding potential synthesis diagnostics and prediction of new properties and functionality.

Advances in Organic-Inorganic Hybrid Latex Particles via In Situ Emulsion Polymerization

Hybrid latex particles combine the unique properties of inorganic nano/micro particles with the inherent properties of polymers, exhibiting tremendous potential for a variety of applications. Recent years have witnessed an increased interest in the design and preparation of hybrid latex particles with well-defined size, structure and morphology. Due to its simplicity, versatility and environmental friendliness, the in situ (Pickering) emulsion polymerization has been demonstrated to be a powerful approach for the large-scale preparation of hybrid latex particles. In this review, the strategies and applications of in situ (Pickering) emulsion polymerization for the preparation of hybrid latex particles are systematically summarized. A particular focus is placed on the strategies for the preparation of hybrid latex particles with enhanced properties and well-defined core-shell, yolk-shell, multinuclear, raspberry-like, dumbbell-shaped, multipod-like or armored morphologies. We hope that the considerable advances, examples and principles presented in this review can motivate future contributions to provide a deeper understanding of current preparation technologies, develop new processes, and enable further exploitation of hybrid latex particles with outstanding characteristics and properties.

Synthesis of new hybrid pyridines catalyzed by Fe3O4@SiO2@urea-riched ligand/Ch-Cl

Herein, a new heterogeneous catalytic system through modification of urea functionalized magnetic nanoparticles with choline chloride [Fe₃O₄@SiO₂@urea-riched ligand/Ch-Cl] was designed and synthesized. Then, the synthesized Fe₃O₄@SiO₂@urea-riched ligand/Ch-Cl was characterized by using FT-IR spectroscopy, FESEM, TEM, EDS-Mapping, TGA/DTG and VSM techniques. After that, the catalytic usage of Fe₃O₄@SiO₂@urea-riched ligand/Ch-Cl was investigated for the synthesis of hybrid pyridines with sulfonate and/or indole moieties. Delightfully, the outcome was satisfactory and the applied strategy represents several advantages such as short reaction times, convenience of operation and relatively good yields of obtained products. Moreover, the catalytic behavior of several formal homogeneous DESs was investigated for the synthesis of target product. In addition, a cooperative vinylogous anomeric-based oxidation pathway was suggested as rational mechanism for the synthesis of new hybrid pyridines.

Nano-Patterned Magnetic Edges in CrGeTe3 for Quasi 1-D Spintronic Devices

The synthesis of two-dimensional van der Waals magnets has paved the way for both technological applications and fundamental research on magnetism confined to ultra-small length scales. Edge magnetic moments in ferromagnets are expected to be less magnetized than in the sample interior because of the reduced amount of neighboring ferromagnetic spins at the sample edge. We recently demonstrated that CrGeTe₃ (CGT) flakes thinner than 10 nm are hard ferromagnets; i.e., they exhibit an open hysteresis loop. In contrast, thicker flakes exhibit zero net remnant field in the interior, with hard ferromagnetism present only at the cleaved edges. This experimental observation suggests that a nontrivial interaction exists between the sample edge and the interior. Here, we demonstrate that artificial edges fabricated by focus ion beam etching also display hard ferromagnetism. This enables us to write magnetic nanowires in CGT directly and use this method to characterize the magnetic interaction between the interior and edge. The results indicate that the interior saturation and depolarization fields depend on the lateral dimensions of the sample. Most notably, the interior region between the edges of a sample narrower than 300 nm becomes a hard ferromagnet, suggesting an enhancement of the magnetic exchange induced by the proximity of the edges. Last, we find that the CGT regions amorphized by the gallium beam are nonmagnetic, which introduces a novel method to tune the local magnetic properties of CGT films, potentially enabling integration into spintronic devices.