Effect of Zn-substitution on magnetic structure of cobalt ferrite nanoparticles.

This study investigates the effects of Zn substitution on the magnetic properties of ∼5 nm cobalt ferrite nanoparticles (ZnxCo1-xFe2O4, where x = 0, 0.13, 0.34, and 0.

Hydrophobic iron oxide nanoparticles: Controlled synthesis and phase transfer via flash nanoprecipitation.

Iron oxide nanoparticles (IONPs) synthesized via thermal decomposition find diverse applications in biomedicine owing to precise control of their physico-chemical properties. However, use in such applications requires phase transfer from organic solvent to water, which remains a bottleneck. Through the thermal decomposition of iron oleate (FeOl), we systematically investigate the impact of synthesis conditions such as oleic acid (OA) amount, temperature increase rate, dwell time, and solvent on the size, magnetic saturation, and crystallinity of IONPs.

Magnetic nanocomposite for lead (II) removal from water.

A magnetic perovskite-spinel oxide nanocomposite synthesized through a sol-gel self-combustion process is used for the first time as an adsorbent to remove toxic heavy metals (i.e., Pb).

Red mud treated with KOH: synthesis of sustainable materials from waste for water treatment.

Solid waste resulting from bauxite ore (red mud) was converted into useful products consisting in hydrogarnet together with zeolite. Red mud (RM) transformation from disposal material into new source was carried out using potassium hydroxide as an activator and hydrothermal process (HY) or vapor phase crystallization (VPC) approach. HY process was performed at 60, 90, and 130 °C whereas during the VPC method, red mud was contacted only with vapor from the distilled water heated at 60 and 90 °C.

Biocatalyst immobilization on magnetic nano-architectures for potential applications in condensation reactions.

In this review article, a perspective on the immobilization of various hydrolytic enzymes onto magnetic nanoparticles for synthetic organic chemistry applications is presented. After a first part giving short overview on nanomagnetism and highlighting advantages and disadvantages of immobilizing enzymes on magnetic nanoparticles (MNPs), the most important hydrolytic enzymes and their applications were summarized. A section reviewing the immobilization techniques with a particular focus on supporting enzymes on MNPs introduces the reader to the final chapter describing synthetic organic chemistry applications of small molecules (flavour esters) and polymers (polyesters and polyamides).

Advancements in polyol synthesis: expanding chemical horizons and Néel temperature tuning of CoO nanoparticles.

The polyol synthesis of CoO nanoparticles (NPs) is typically conducted by dissolving and heating cobalt acetate tetrahydrate and water in diethylene glycol (DEG). This process yields aggregates of approximately 100 nm made of partially aligned primary crystals. However, the synthesis demands careful temperature control to allow the nucleation of CoO while simultaneously preventing reduction, caused by the activity of DEG.

Chemical engineering of cationic distribution in spinel ferrite nanoparticles: the effect on the magnetic properties.

A set of ∼9 nm CoFeO nanoparticles substituted with Zn and Ni was prepared by thermal decomposition of metallic acetylacetonate precursors to correlate the effects of replacement of Co with the resulting magnetic properties. Due to the distinct selectivity of these cations for the spinel ferrite crystal sites, we show that it is possible to tailor the magnetic anisotropy, saturation magnetization, and interparticle interactions of the nanoparticles during the synthesis stage. This approach unlocks new possibilities for enhancing the performance of spinel ferrite nanoparticles in specific applications.

Iron Oxide Nanoparticle-Assisted Delamination of TiCT MXenes: A New Approach to Produce Magnetic MXene-Based Composites.

TiCT MXene is one of the most comprehensively studied 2D materials in terms of its adsorptive, transport, and catalytic properties, cytotoxic performance, etc. Still, conventional MXene synthesis approaches provide low single-flake MXene yield and frequently uncontrollable properties, demanding further post-processing. The MXene family also lacks magnetism, which is helpful for producing effective nanoadsorbents as their magnetic decantation is the cheapest and most convenient way to remove the spent adsorbent from water.

Template-free generation and integration of functional 1D magnetic nanostructures.

The direct integration of 1D magnetic nanostructures into electronic circuits is crucial for realizing their great potential as components in magnetic storage, logical devices, and spintronic applications. Here, we present a novel template-free technique for producing magnetic nanochains and nanowires using directed self-assembly of gas-phase-generated metallic nanoparticles. The 1D nanostructures can be self-assembled along most substrate surfaces and can be freely suspended over micrometer distances, allowing for direct incorporation into different device architectures.

Unraveling Exchange Coupling in Ferrites Nano-Heterostructures.

The magnetic coupling of a set of SrFe O /CoFe O nanocomposites is investigated. Advanced electron microscopy evidences the structural coherence and texture at the interfaces of the nanostructures. The fraction of the lower anisotropy phase (CoFe O ) is tuned to assess the limits that define magnetically exchange-coupled interfaces by performing magnetic remanence, first-order reversal curves (FORCs), and relaxation measurements.

Tunable particle-agglomeration and magnetic coupling in bi-magnetic nanocomposites.

A set of non-stoichiometric Zn-Co-ferrite nanoparticles (NPs) was prepared by thermal decomposition of metallic complexes, in the presence of oleic acid, and, after a ligand-exchange process, was coated by a hydrophilic surfactant: these NPs were used as seeds in a sol-gel self-combustion synthesis to prepare nanocomposites (NCs) with a fixed weight ratio. Our focus here is the development of an efficient synthetic approach to control the magnetic coupling between a hard-magnetic matrix (Sr-ferrite) and NPs. The physico-chemical synthetic conditions (temperature, pH, colloidal stability) were optimized in order to tune their effect on the final particles' agglomeration in the matrix.

FeO-Halloysite Nanotube Composites as Sustainable Adsorbents: Efficiency in Ofloxacin Removal from Polluted Waters and Ecotoxicity.

The present work aimed at decorating halloysite nanotubes (HNT) with magnetic FeO nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/FeO) to remove the antibiotic ofloxacin (OFL) from waters. The chemical-physical features of the obtained materials were characterized through the application of diverse techniques (XRPD, FT-IR spectroscopy, SEM, EDS, and TEM microscopy, thermogravimetric analysis, and magnetization measurements), while ecotoxicity was assessed through a standard test on the freshwater organism . Independently of the synthesis procedure, the magnetic composites were successfully obtained.

Effect of Piezoelectric BaTiO Filler on Mechanical and Magnetoelectric Properties of ZnCoFeO/PVDF-TrFE Composites.

Polymer-based multiferroics, combining magnetic and piezoelectric properties, are studied experimentally-from synthesis to multi-parameter characterization-in view of their prospects for fabricating biocompatible scaffolds. The main advantage of these systems is facile generation of mechanical deformations and electric signals in response to external magnetic fields. Herein, we address the composites based on PVDF-TrFE polymer matrices filled with a combination of piezoelectric (BaTiO BTO) and/or ferrimagnetic (ZnCoFeO, ZCFO) particles.

Hardening of Cobalt Ferrite Nanoparticles by Local Crystal Strain Release: Implications for Rare Earth Free Magnets.

In this work, we demonstrate that the reduction of the local internal stress by a low-temperature solvent-mediated thermal treatment is an effective post-treatment tool for magnetic hardening of chemically synthesized nanoparticles. As a case study, we used nonstoichiometric cobalt ferrite particles of an average size of 32(8) nm synthesized by thermal decomposition, which were further subjected to solvent-mediated annealing at variable temperatures between 150 and 320 °C in an inert atmosphere. The postsynthesis treatment produces a 50% increase of the coercive field, without affecting neither the remanence ratio nor the spontaneous magnetization.

Effect of albumin coating on the magnetic behavior of Mn ferrite nanoclusters.

The effect of clustering induced by albumin coating on the magnetic behaviour of ultra-small MnFeO nanoparticles has been systematically investigated and compared with that in pure Mn ferrite nanoparticle dense assembly, using a mesoscopic scale approach and numerical simulations reproducing the experimental findings well. Our results provide evidence that in the coated system, the interplay between intra-particle and intra-cluster exchange interactions strongly affects the exchange bias and coercive field values, with the dipolar interactions playing a minor role. Instead, the albumin coating does not affect the thermal stability of the observed superspin glass phase, the freezing temperature being similar in the coated and uncoated systems.

The Boundary Between Volume and Surface-Driven Magnetic Properties in Spinel Iron Oxide Nanoparticles.

Despite modern preparation techniques offer the opportunity to tailor the composition, size, and shape of magnetic nanoparticles, understanding and hence controlling the magnetic properties of such entities remains a challenging task, due to the complex interplay between the volume-related properties and the phenomena occurring at the particle's surface. The present work investigates spinel iron oxide nanoparticles as a model system to quantitatively analyze the crossover between the bulk and the surface-dominated magnetic regimes. The magnetic properties of ensembles of nanoparticles with an average size in the range of 5-13 nm are compared.

Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles.

The synthesis strategy and magnetic characterisation of two systems consisting of nanoparticles with core/shell morphology are presented: an assembly of hard/soft nanoparticles with cores consisting of magnetically hard cobalt ferrite covered by a magnetically soft nickel ferrite shell, and the inverse system of almost the same size and shape. We have successfully designed these nanoparticle systems by gradually varying the magnetic anisotropy resulting in this way in the modulation of the magnetic dipolar interactions between particles. Both nanoparticle systems exhibit high saturation magnetisation and display superparamagnetic behaviour at room temperature.

Magnetic Nanoclusters Increase the Sensitivity of Lateral Flow Immunoassays for Protein Detection: Application to Pneumolysin as a Biomarker for .

Lateral flow immunoassays for detecting biomarkers in body fluids are simple, quick, inexpensive point-of-care tests widely used in disease surveillance, such as during the coronavirus disease 2019 (COVID-19) pandemic. Improvements in sensitivity would increase their utility in healthcare, food safety, and environmental control. Recently, biofunctional magnetic nanoclusters have been used to selectively label target proteins, which allows their detection and quantification with a magneto-inductive sensor.

Crossover From Individual to Collective Magnetism in Dense Nanoparticle Systems: Local Anisotropy Versus Dipolar Interactions.

Dense systems of magnetic nanoparticles may exhibit dipolar collective behavior. However, two fundamental questions remain unsolved: i) whether the transition temperature may be affected by the particle anisotropy or it is essentially determined by the intensity of the interparticle dipolar interactions, and ii) what is the minimum ratio of dipole-dipole interaction (E ) to nanoparticle anisotropy (K V, anisotropy⋅volume) energies necessary to crossover from individual to collective behavior. A series of particle assemblies with similarly intense dipolar interactions but widely varying anisotropy is studied.

Double-Layer Fatty Acid Nanoparticles as a Multiplatform for Diagnostics and Therapy.

Today, public health is one of the most important challenges in society. Cancer is the leading cause of death, so early diagnosis and localized treatments that minimize side effects are a priority. Magnetic nanoparticles have shown great potential as magnetic resonance imaging contrast agents, detection tags for in vitro biosensing, and mediators of heating in magnetic hyperthermia.

Complex correlations between microstructure and magnetic behavior in SrFeO hexaferrite nanoparticles.

The magnetic properties of SrFeO (SFO) hard hexaferrites are governed by the complex relation to its microstructure, determining their relevance for permanent magnets´ applications. A set of SFO nanoparticles obtained by sol-gel self-combustion synthesis was selected for an in-depth structural X-Rays powder diffraction (XRPD) characterization by means of G(L) line-profile analysis. The obtained crystallites´ size distribution reveal a clear dependence of the size along the [001] direction on the synthesis approach, resulting in the formation of platelet-like crystallites.

Magnetism of Nanoparticles: Effect of the Organic Coating.

The design of novel multifunctional materials based on nanoparticles requires tuning of their magnetic properties, which are strongly dependent on the surface structure. The organic coating represents a unique tool to significantly modify the surface structure trough the bonds between the ligands of the organic molecule and the surface metal atoms. This work presents a critical overview of the effects of the organic coating on the magnetic properties of nanoparticles trough a selection of papers focused on different approaches to control the surface structure and the morphology of nanoparticles' assemblies.

Combined Bottom-Up and Top-Down Approach for Highly Ordered One-Dimensional Composite Nanostructures for Spin Insulatronics.

Engineering magnetic proximity effects-based devices requires developing efficient magnetic insulators. In particular, insulators, where magnetic phases show dramatic changes in texture on the nanometric level, could allow us to tune the proximity-induced exchange splitting at such distances. In this paper, we report the fabrication and characterization of highly ordered two-dimensional arrays of LaFeO (LFO)-CoFeO (CFO) biphasic magnetic nanowires, grown on silicon substrates using a unique combination of bottom-up and top-down synthesis approaches.

Boosting Magnetoelectric Effect in Polymer-Based Nanocomposites.

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (α) of the magnetoelectric effect.