Search Results (292)

Background: Magnetic particle imaging (MPI) is an emerging, tracer-based modality that directly detects superparamagnetic iron oxide nanoparticles (SPIONs) with exceptional sensitivity, quantitative signal behavior, and full immunity to air–tissue susceptibility artifacts. These features make MPI particularly well-suited for pulmonary imaging, where traditional techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine-based ventilation/perfusion (V/Q) imaging are limited by radiation exposure, low contrast, and motion-related signal degradation. Objective: This review synthesizes the current state of MPI for lung imaging, with emphasis on its physical principles, tracer development, preclinical applications, and its potential role in assessing pulmonary perfusion, vascular integrity, inflammation, and therapeutic responses. Methods: A systematic evaluation of preclinical studies was performed across three major application domains: pulmonary perfusion mapping, cell tracking and therapeutic monitoring, and vascular injury and permeability assessment. Study designs, SPION formulations, MPI acquisition strategies, and validation methods, including histopathology, biodistribution, broncho-alveolar lavage fluid (BALF) analysis, and Evans Blue assays, were examined to characterize methodological consistency and imaging performance. Results: MPI consistently demonstrated high-contrast, quantitative visualization of pulmonary blood flow, endothelial barrier disruption, inflammatory signaling, and transplanted or inhaled cell populations. Tracer engineering played a critical role: macroaggregated albumin superparamagnetic iron oxide nanoparticles (MAA-SPIONs) enabled capillary-level perfusion mapping, LS-008 improved temporal resolution and vascular delineation, Synomag/Synomag-D allowed quantification of vascular leakage in acute and chronic lung injury, and vascular cell adhesion molecule-1 (VCAM-1)-targeted probes provided molecular-level assessment of inflammation. Hybrid MPI-CT and MPI-MRI approaches further enhanced anatomic localization and enabled accurate pulmonary blood volume (PBV) estimation. Across studies, MPI measurements showed strong agreement with established biological assays and remained free of the artifacts that limit CT and MRI in the lung. Conclusions: Preclinical evidence demonstrates that MPI is a robust, radiation-free, and quantitatively precise modality for functional and molecular lung imaging. Its ability to map perfusion, track therapeutic agents, and noninvasively quantify vascular permeability positions MPI as a promising future alternative or complement to CT, MRI, and nuclear medicine for pulmonary assessment. Continued tracer optimization, system scaling, and clinical validation are key steps toward translating MPI into routine clinical use. Full article

The field of nanoparticle-based biotechnology has undergone substantial advancement, characterized by progress in targeted drug delivery systems, the development of innovative diagnostic and imaging platforms, the expanded adoption of environmentally sustainable (“green”) synthesis approaches, and an increasing emphasis on the integration of emerging technologies such as artificial intelligence and nanorobotics. Conventional nanoparticle synthesis often involves toxic reducing agents; however, recent advances promote eco-friendly green synthesis methods utilizing biological systems such as bacteria, fungi, algae, yeast, plants, and actinomycetes. These biological approaches are safe, sustainable, cost-effective, and capable of producing highly stable Nanoparticles (NPs). The interaction of nanomaterials with biological systems is crucial for developing intracellular and subcellular drug delivery technologies with minimal toxicity, governed by nano–bio interface mechanisms such as cellular translocation, surface wrapping, embedding, and internal attachment. Key factors influencing NP behavior include morphology, size, surface area, surface charge, and ligand chemistry. Magnetic nanoparticles, particularly iron-based forms, exhibit unique superparamagnetic properties that are strongly influenced by particle size, as explained by the Néel relaxation mechanism, in which thermal energy induces flipping of magnetic moments. Nanoparticles demonstrate diverse modes of action, including antimicrobial activity, reactive oxygen species (ROS)-induced cytotoxicity, genotoxicity, and plant growth promotion. NP performance and biological effects are strongly dependent on their size, shape, dosage, and concentration. This critical review article aims to elucidate evolution, classification, preparation methods, and multifaceted applications of nanoparticles. Full article

Background: Magnetic Particle Imaging (MPI) is an emerging biomedical imaging modality that detects superparamagnetic iron oxide nanoparticles (SPIONs), providing high contrast, sensitivity, and quantification capabilities without ionizing radiation, making it particularly suitable for cancer diagnostics. Considerable engineering efforts are underway to translate MPI technology to clinical settings. Most of these MPI scanners feature a cylindrical bore geometry similar to that of other clinical imaging modalities, which limits their potential application primarily to head scanning. Methods: We have developed a single-sided MPI scanner designed to expand the modality’s applicability to other regions of the human body through a unique hardware design developed in our previous work. Imaging experiments were performed on an anatomical breast phantom containing implanted SPION point sources placed at anatomically plausible locations for breast tumors. These point sources served as artificial tumors for evaluating the system’s suitability for breast imaging applications. Results: The scanner successfully detected and clearly resolved the implanted SPION tumors in two orthogonal imaging planes. Tumor positioning was independently validated by ultrasound imaging, confirming MPI’s accurate localization. In addition, sensitivity measurements demonstrated a detection limit of 4.0 $\mathsf{\mu }\mathrm{g}$ of iron, below the estimated 4.8 $\mathsf{\mu }\mathrm{g}$ sensitivity threshold required for breast tumor detection with electronic depth scanning up to 3.5 cm deep. Conclusions: Together, these results demonstrate the capability of a single-sided MPI geometry for breast imaging applications. Imaging an anatomical breast-shaped volume presents significant challenges for MPI due to the size and accessibility constraints of conventional hardware. The results presented highlight the advantages of this approach and support its potential to extend MPI from small-animal imaging to clinically relevant applications. Full article

This study investigates magnetic harvesting of Chlorella vulgaris cultivated under saline and wastewater conditions using Fe₃O₄ and polyethylene-glycol-coated Fe₃O₄ (Fe₃O₄@PEG) nanoparticles synthesized by ultrasound-assisted coprecipitation. TEM showed agglomerated, quasi-spherical particles with mean diameters of 13 ± 1 nm (Fe₃O₄) and 15 ± 1 nm (Fe₃O₄@PEG). FTIR confirmed the Fe–O vibrational bands of magnetite and the characteristic PEG vibrations in the coated sample. VSM measurements indicated superparamagnetic behavior, with saturation magnetizations of 72.74 emu/g for Fe₃O₄ and 32.25 emu/g for Fe₃O₄@PEG. SEM–EDX of native and functionalized cells verified nanoparticle attachment on the algal surface. Magnetic separation experiments (OD684) showed a decrease in supernatant absorbance with increasing nanoparticle dose, consistent with biomass removal; the PEG-coated system showed a lower apparent biomass concentration after functionalization. Full article

Background/Objectives: Magnetic nanoparticles have emerged as powerful tools for biomedical imaging, targeted drug delivery, and hyperthermia therapy. Magnetic particle imaging (MPI) is among the most promising technologies built around its properties: a radiation-free, quantitative tomographic modality that detects superparamagnetic iron oxide nanoparticles (SPIONs) directly against a biologically silent background. This review synthesizes MPI’s physical principles, nanoparticle design strategies, and preclinical applications within the broader landscape of magnetic material engineering for biomedical use. Methods: A systematic review was conducted covering MPI signal generation and image reconstruction, nanoparticle core synthesis and surface coating approaches, and preclinical applications, spanning cell tracking, oncological imaging, vascular perfusion, neuroimaging, and MPI-guided theranostics. Studies were selected to provide quantitative benchmarks and direct comparisons with competing modalities where available. Results: MPI delivers signal-to-background ratios above 1000:1, iron-mass linearity at R² ≥ 0.99, regardless of tissue depth, and acquisition rates up to 46 volumes per second. Tracer architecture—encompassing single-core particles, multicore nanoflowers, and stimuli-responsive cluster designs—is the primary determinant of sensitivity, environmental robustness, and theranostic capability. Preclinical results include detection of cell populations in the low thousands, earlier ischaemia identification than diffusion-weighted MRI, real-time drug release quantification, and spatially confined tumour hyperthermia. Three translational bottlenecks are identified: the absence of a clinically approved tracer with optimal relaxation dynamics, hardware performance losses when scaling to human-bore systems, and overestimation of passive tumour accumulation in murine models. Conclusions: MPI illustrates how progress in magnetic material design directly expands clinical imaging and theranostic possibilities. Successful translation will require indication-driven, interdisciplinary development that integrates materials science, scanner engineering, and regulatory strategy in parallel. Full article

In this study, representative soil profiles developed on clastic rock parent materials in Yunnan Province were investigated to elucidate the formation mechanisms of soil magnetic properties under weakly magnetic parent material conditions and to evaluate the response of magnetic enhancement to chemical weathering and pedogenic differentiation. A combination of environmental magnetic measurements, bulk geochemical analyses, weathering index calculations, and ternary diagram discrimination was applied to characterize soil magnetic behavior, magnetic grain size distribution, and chemical weathering processes. The results show that the clastic rock parent materials exhibit overall low magnetic intensities, with low-frequency magnetic susceptibility (χ_lf) ranging from 2.543 × 10⁻⁸ m³/kg to 595.652 × 10⁻⁸ m³/kg. Under this weakly magnetic background, soils in the study area display pronounced pedogenic magnetic enhancement, with magnetic parameters showing clear and systematic vertical differentiation along soil profiles, indicating that soil magnetic signals are primarily controlled by pedogenesis. The frequency-dependent susceptibility (χ_fd%) generally falls within the range of 5.403%–17.574%, with a mean value of 12.898%, suggesting a substantial contribution from fine-grained magnetic particles. Magnetic grain size diagnostics further indicate that newly formed superparamagnetic (SP) and stable single-domain (SSD) particles generated during pedogenesis dominate the magnetic enhancement signal. The results of the Chemical Index of Alteration (CIA) indicate that approximately 78% of the profiles reach the strong weathering category (CIA > 85), while only 22% fall into the moderate weathering category (CIA: 65–85). Correlation analyses further reveal that grain-size-sensitive magnetic ratios (e.g., χ_fd%, χ_ARM/SIRM) exhibit a strong correspondence with chemical weathering intensity indicators. These findings suggest that, under weakly magnetic parent material conditions, pedogenically induced magnetic enhancement can be more readily identified and quantitatively assessed. The integration of environmental magnetism and geochemical approaches, therefore, provides a robust framework for investigating pedogenic differentiation and supports high-resolution paleoenvironmental reconstruction in regions dominated by weakly magnetic parent materials. Full article

The aim of this study was to synthesize alginate hydrogel beads using ionotropic gelation containing pH-sensitive magnetic reduced graphene oxide (MGO). MGO was prepared using a hydrothermal method and surrounded by alginate beads. FTIR, XRD, FESEM, TEM, VSM and TGA showed that the synthesized beads have a quasi-spherical structure, exhibit superparamagnetic behavior, and are thermally stable up to 350 °C. The model drug, quercetin, was loaded into these particles with an efficiency of 25.8%. These particles showed a pH-dependent release. HFF-2 and Caco-2 cells were used to investigate cytotoxicity. At a concentration of 140 μg/mL, more than 80% viability was observed in HFF-2 cells and anticancer effects were observed on Caco-2 cells with a decrease in viability of less than 50% at a concentration of 200 μg/mL. The obtained cell culture results indicate that the hydrogel beads are biocompatible and act as a drug delivery system. Full article

Nanoparticles of ferrimagnetic magnetite (Fe₃O₄) are cornerstones of modern nanoscience and technology, primarily due to their superparamagnetic behavior. Beyond traditional applications in magnetorheology and magnetic hyperthermia, these materials are increasingly vital in fields like active matter, where precise surface fine-tuning is crucial. While coating isotropic, quasi-spherical magnetite nanoparticles with silica is a well-established and versatile route towards functionalization, transferring this achievement to nanorod systems remains a significant challenge. Successful coating of these high-aspect-ratio geometries would allow to exploit the direction-dependent properties and increased magnetic anisotropies. However, current literature largely focuses on polycrystalline rods composed of small, clustered subunits, which limits their magnetic potential. This work describes a breakthrough in the homogeneous silica coating and stabilization of monocrystalline magnetite nanorods. We demonstrate that the superior magnetic properties of these “naked” monocrystalline rods induce strong dipole-dipole interactions, which trigger aggregation and typically prevent the isolation of individual and homogeneously coated core-shell nanoparticles. By investigating the specific mechanisms of this aggregation, we established a robust coating procedure that yields the desired isolated particles. Critically, we show that the magnetite nanorods retain their monocrystalline integrity within the silica shell, thereby preserving the enhanced magnetic properties of the original nanocrystals. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) are commonly produced through wet-chemical methods that require high temperature and pressure and involve multiple synthesis steps. Our research group has developed an innovative, sustainable, and patented one-step aqueous synthesis operating at ambient temperature and pressure, enabling the direct production of SPIONs in suspension. In this work, we investigated the extension of this method to obtain polymer-coated SPIONs for biomedical imaging applications. Two water-soluble and biocompatible polymers—poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)—were selected and prepared into twelve samples varying in polymer concentration and iron precursor molarity. Each formulation was characterized and compared to bare SPIONs synthesized with the same approach using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and alternating gradient magnetometry (AGM). The results confirm that the one-step method yields polymer-coated nanoparticles with a cubic spinel magnetite core. PEG produced spherical, monodisperse particles (10–30 nm) exhibiting superparamagnetic behavior but lower magnetization values (1–5 emu/g). In contrast, PVA-coated nanoparticles showed a morphology dependent on polymer concentration and reagent molarity, while maintaining an average size of ~10 nm and superparamagnetic behavior, with magnetization comparable to bare SPIONs (25–50 emu/g). A preliminary MRI evaluation of a selected PVA-coated sample revealed relaxivity values of r₁ = 0.12 mM⁻¹ s⁻¹ and r₂ = 6.44 mM⁻¹ s⁻¹, supporting the potential of this synthesis route for imaging-oriented nanomaterials. Full article

A comprehensive study of the magnetic properties of baked clays containing ferrimagnetic particles in various magnetic states, including superparamagnetic, has been carried out in this work. The phase composition of the magnetic fraction of laboratory and industrial samples made from the same clay is mainly represented by iron (III) oxide polymorphs and possibly non-stoichiometric magnetite. Experimental methods included magnetic granulometry, Mössbauer spectroscopy, scanning electron microscopy, X-ray phase analysis, and pulsed electromagnetic measurements. A theoretical model of magnetostatically interacting particles with a lognormal volume distribution was used to interpret the experimental data, allowing the contribution of superparamagnetic grains to be taken into consideration. It is shown that the firing mode significantly affects the composition of iron oxide phases and their magnetic characteristics. Laboratory samples are characterized by approximately twice the proportion of superparamagnetic particles. At sufficiently low concentrations of ferrimagnet in samples <0.1%, the concentration of superparamagnetic particles is even two orders of magnitude lower. It is the use of pulse methods that provides a more reliable diagnosis of their presence. The complex application of experimental methods with theoretical modeling makes it possible to reveal and quantitatively describe the microheterogeneous nature of the magnetic state of baked clays, which is applicable to a wide range of magnetic materials, and to analyze more deeply the thermal and phase history of archaeological and geological objects. Full article

Cu-modified ferrites, prepared by solvothermal syntheses, at up to 200 °C, show the presence of copper metal particles, embedded in ferrite nanocrystalline particle agglomerates. Notably, these metallic copper micron-sized crystallites were dramatically reduced in size, down to a few tens of nanometers, when part of the copper dopant was replaced by zinc. All materials were magnetic due to the presence of the cubic spinel phase, being ferrimagnetic, measured with external fields up to 6000 Oe, showing a narrow hysteresis of 89 Oe for the largest particle size copper ferrite material of 15 nm. Superparamagnetic behavior was observed for the smallest size, e.g., 11 nm, Cu-doped and the zinc-doped, 9–10 nm average particle size ferrites. The redox activity of the materials was studied in free-radical oxidation reactions (pH 7.4, physiological and pH 8.5, optimal) by the chemiluminescent method with (i) Fenton’s reagent (^·OH, ^·OOH); (ii) H₂O₂; and (iii) O₂^·− radicals. All materials presented extremely strong inhibitory activities (converted to prooxidant only at pH 7.4 in system iii, excluding the largest isolated copper-particle-containing material, which remained inhibitory). The materials’ antimicrobial potential was checked on Gram-positive and Gram-negative bacteria, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923 via two classical methods, namely the spot and well diffusion tests in agar medium. The above tests included a nanocrystalline CuO, tenorite, as a reference material too. The Daphnia magna ecotoxicity test showed that all of the investigated materials are rather toxic, and since daphnia is a key component in freshwater ecosystems, the toxicity even at low concentrations may have significant consequences for the ecological balance. This requires careful monitoring and assessment of the possible use or disposal of these nanomaterials in the environment. Full article

Co-TiO₂ materials have rich magnetic and electronic properties for advanced magnetoresistance (MR) sensing field. The non-uniform Co-TiO₂ nanocomposite films are prepared via magnetron sputtering. With substrate temperature increasing, the particles undergo agglomeration, and this non-uniform structure transits from the superparamagnetic-particle Co distribution to the particle-cluster Co distribution. Consequently, the MR decreases from 6% to 1%, owing to low resistivity. To investigate the electronic transport mechanism, the microstructural analysis and temperature-dependent fitting calculations of conduction and MR were investigated. In this study, non-uniform nanocomposite films with a broad particle size distribution were fabricated. With testing temperature decreasing, electron transport changes from higher order hopping to higher order cotunneling processes. The non-uniform films deposited at room temperature exhibited a negative MR up to 30% at 2 K, which was attributed to higher order cotunneling in the Coulomb blockade regime and explained by establishing a non-uniform multi-channel conduction model. Full article

Magnetic Particle Imaging (MPI) is a new type of tracer-based imaging that has great spatial and temporal resolution, does not require ionizing radiation, and can see deep into tissues by directly measuring the nonlinear magnetization response of superparamagnetic iron oxide nanoparticles (SPIONs). Unlike Magnetic Resonance Imaging (MRI) or Computed Tomography (CT), MPI has very high contrast and quantitative accuracy, which makes it perfect for use in dynamic cardiovascular applications. This study presents a full picture of the most recent changes in cardiac MPI, such as the physics behind Field-Free Point (FFP) and Field-Free Line (FFL) encoding, new ideas for tracer design, and important steps in the evolution of scanner hardware. We discuss the clinical relevance of cardiac MPI in visualizing myocardial perfusion, quantifying blood flow, and guiding real-time interventions. A hybrid imaging workflow, which improves anatomical detail and functional assessment, is utilized to explore the integration of MPI with complementary modalities, particularly MRI. By consolidating recent preclinical breakthroughs and highlighting the roadmap toward human-scale implementation, this article underscores the transformative potential of MPI in cardiac diagnostics and image-guided therapy. Full article

Electromagnetic heating (EMH) using microwaves has emerged as a promising enhanced oil recovery (EOR) technique, particularly for heavy crude oils where conventional thermal methods encounter technical and environmental challenges. However, its large-scale implementation remains limited due to incomplete understanding of its energy transfer mechanisms. This study proposes an experimental–numerical approach integrating magnetic graphene oxide nanoparticles (Fe₃O₄@GO) with microwave heating to enhance energy absorption near the wellbore. The nanomaterial was synthesized via a modified Hummer’s method followed by in situ magnetite precipitation and studied through multiple material characterization techniques showing uniform 80 nm particles with superparamagnetic behavior—ideal for EMH applications. Nine experiments were conducted on sand–heavy-oil–water systems with nanoparticle concentrations up to 500 ppm using a laboratory microwave heating prototype. A simulation model was then developed in CMG-STARS for history matching to estimate energy absorption as a function of saturation and nanoparticle concentration. Experiments reached temperatures up to 240 °C, with 653 MJ of effective heat transferred to the target zone over 55 h, as estimated from the input heat required in the simulator for history matching. The results confirm that magnetic graphene oxide nanoparticles enhance thermal efficiency and heat distribution in microwave-assisted EOR. Full article

Magnetic Particle Imaging (MPI) is a cutting-edge noninvasive imaging technique that offers high sensitivity, quantitative accuracy, and operates without the need for ionizing radiation compared to other imaging techniques. Utilizing superparamagnetic iron oxide nanoparticles (SPIONs) as tracers, MPI enables direct and precise visualization of target sites with no limitation on imaging depth. Unlike magnetic resonance imaging (MRI), which relies on uniform magnetic fields to produce anatomical images, MPI enables direct, background-free visualization and quantification of SPIONS within living organisms. This article provides an in-depth overview of MPI’s applications in tracking tumor development and supporting cancer therapy. The distinct physical principles that underpin MPI, including its ability to produce high-contrast images devoid of background tissue interference, facilitating accurate tumor identification and real-time monitoring of treatment outcomes, are outlined. The review outlines MPI’s advantages over conventional imaging techniques in terms of sensitivity and resolution, and examines its capabilities in visualizing tumor vasculature, tracking cellular movement, evaluating inflammation, and conducting magnetic hyperthermia treatments. Recent progress in tracer optimization and magnetic navigation has expanded MPI’s potential for targeted drug delivery, along with deep machine learning procedures for MPI applications. Additionally, considerations around safety and the feasibility of clinical implementation are also discussed in the present review. Overall, MPI is positioned as a promising tool in advancing cancer diagnostics, personalized therapy assessment, and noninvasive treatment strategies. Full article