Search Results (134)

Iron-based nanoparticles, particularly iron oxide nanostructures (IONPs), have emerged as versatile and clinically relevant platforms for drug delivery and theranostic applications. Among these, superparamagnetic iron oxide nanoparticles (SPIONs), including magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃), are the most extensively investigated due to their biocompatibility, magnetic responsiveness, and established safety profiles. Their unique superparamagnetic behavior enables external magnetic-field-guided targeting, magnetic resonance imaging (MRI) contrast enhancement, and magnetically triggered hyperthermia, enabling simultaneous diagnosis and therapy. Surface functionalization with polymers, silica, lipids, peptides, and biomolecules further improves colloidal stability, circulation time, targeting specificity, and controlled drug release. Core–shell architectures and multifunctional hybrid systems have expanded the therapeutic scope of iron nanoparticles, integrating chemotherapy, gene delivery, photothermal therapy, and Fenton reaction–mediated catalytic therapy. Despite promising preclinical outcomes, challenges remain regarding long-term biosafety, oxidative stress induction, biodistribution, large-scale reproducibility, and regulatory translation. This review summarizes the physicochemical properties, synthesis strategies, surface-engineering approaches, drug-loading mechanisms, and biomedical applications of iron-based nanoparticles, highlighting recent advances in multifunctional and peptide-functionalized systems. Critical considerations for clinical translation and future perspectives in precision nanomedicine are also discussed. Full article

In search of a non-surgical alternative for male animal sterilization, this study investigated the use of gold-coated maghemite nanoparticles (γ-Fe₂O₃@Au) functionalized with citrate to produce testicular photohyperthermia (PHT). Wistar rats received an intratesticular injection of the fluid containing the nanoparticles (150 µL/testicle) followed by testicular irradiation with an LED light (808 nm). Testicular temperature was maintained at ~45 °C for 15 min. The results demonstrated a significant reduction in testicular volume and weight and sperm motility and normal morphology in PHT-treated animals, together with histopathological degeneration of seminiferous tubules. No treatment-related side effects or signs of systemic toxicity were observed. The biodistribution of the gold (Au) and iron (Fe) from the nanoparticles showed that the testes were the primary site of nanoparticle accumulation until day 56 post-treatment with possible renal excretion of Au. These findings support the prospect of testicular PHT mediated by γ-Fe₂O₃@Au nanoparticles as a neutering method for male animals. Full article

Iron oxide particles (magnetite Fe₃O₄, hematite α-Fe₂O₃, and maghemite γ-Fe₂O₃) are prevalent constituents of atmospheric particulate matter (PM) and have gained increasing attention due to potential health implications. This scoping review provides a broad mapping of published in vivo and in vitro studies addressing the biological and toxicological effects of iron oxide particles across particle size fractions (PM10, PM2.5, PM1.0, and nanoscale) and exposure routes, including inhalation, intranasal instillation, and intravenous administration. As a scoping review, no formal risk-of-bias appraisal was conducted; however, studies were selected through predefined eligibility criteria and a structured screening workflow. Iron oxide exposure is consistently associated with oxidative stress and inflammatory responses, while mitochondrial dysfunction, genotoxicity, and neurological effects are frequently reported depending on particle characteristics and exposure context. Among studies with explicit crystalline phase identification, magnetite is most frequently associated with higher biological reactivity, whereas hematite and maghemite display more variable and context-dependent responses. Limited human evidence aligns with experimental findings, identifying magnetite-rich nanoparticles in neural and cardiovascular tissues alongside markers of oxidative and mitochondrial damage. Overall, this scoping review highlights dominant research trends, mechanistic pathways, and key knowledge gaps regarding iron oxide-containing PM, emphasizing the need for integrative approaches linking atmospheric particle characterization with toxicological research. Full article

The usage of magnetic nanoparticles (MNPs), particularly iron oxide-based systems such as magnetite (${\mathrm{Fe}}_3$${\mathrm{O}}_4$) and maghemite ($\gamma$-${\mathrm{Fe}}_2$${\mathrm{O}}_3$), has significantly advanced the field of theranostics. These nanoparticles unite therapeutic and diagnostic capabilities due to their favorable magnetic properties and surface engineering potential. However, the path from synthesis to clinical application poses substantial challenges, including optimization of structure–property–function relationships, biocompatibility issues, and effective surface functionalization. Various synthesis methods, such as co-precipitation and thermal decomposition, aim to achieve specific nanoparticle characteristics, although they encounter obstacles related to scalability and reproducibility. Furthermore, characterizing these systems through structural, microstructural and spectroscopic techniques is vital to determine their functional efficacy and ensure their safe biomedical usage. This review comprehensively examines recent advancements and identifies existing challenges in the clinical translation of MNPs, highlighting the need for refined methods and standardized protocols to effectively exploit their theranostic potential. It outlines future directions, emphasizing the importance of green synthesis and robust characterization frameworks to enhance the integration of MNPs in personalized medicine. Full article

Mining tailings are considered a significant environmental challenge due to their large quantities and high residual metal content, particularly iron. Recent developments in biogenic technologies offer a sustainable approach to recovering valuable materials from these waste streams. We consider a biogenic iron oxide nanoparticles production process from mining tailings as an environmentally friendly route to magnetic materials. Microorganisms, including iron-oxidizing and iron-reducing bacteria, microalgae, and fungi, can convert soluble and mineral-bound iron into iron oxide nanoparticles (NPs) phases such as magnetite, maghemite, and hematite. These biogenic iron oxide NPs often exhibit specific physicochemical properties, including controlled particle size, high surface area, and engineered magnetic properties, which make them potentially important for applications in environmental remediation, catalysis, and agriculture. The processes behind microbial iron conversion, the parameters governing mineral phase formation, and the approaches for optimizing the process are presented. This strategy supports the circular economy concept by combining biogenic synthesis with various forms of mining waste, thereby reducing environmental threats associated with tailings confinement and providing an environmentally friendly mechanism for the production of value-added magnetic materials. Full article

Magnetite (Fe₃O₄) nanoparticles are biocompatible, non-toxic, and easily functionalized. Coating them with mesoporous silica (mSiO₂) offers high surface area, pore volume, and tunable surface chemistry for drug loading. In this study, Fe₃O₄ magnetic nanoparticles were synthesized and coated with mSiO₂ shells enriched with calcium ions (Ca²⁺), aiming to enhance bioactivity for bone regeneration and tissue engineering. Different synthesis routes were tested to optimize shell formation Their characterization confirmed the presence of a crystalline Fe₃O₄ core with partial conversion to maghemite (Fe₂O₃) post-coating. The silica shell was mostly amorphous and the optimized samples exhibited mesoporous structure (type IVb). Calcium incorporation slightly altered the magnetic properties without significantly affecting core crystallinity or particle size (11.68–13.56 nm). VSM analysis displayed symmetric hysteresis loops and decreased saturation magnetization after coating and Ca²⁺ addition. TEM showed spherical morphology with some agglomeration. MTT assays confirmed overall non-toxicity, except for mild cytotoxicity at high concentrations in the Ca²⁺-enriched sample synthesized by a modified Stöber method. Their capacity to induce human periodontal ligament cell osteogenic differentiation, further supports the potential of Fe₃O₄/mSiO₂/Ca²⁺ core–shell nanoparticles as promising candidates for bone-related biomedical applications due to their favorable magnetic, structural, and biological properties. Full article

This study aimed to clarify the interactions between cobalt-adsorbed Chlorella vulgaris cells and amine-functionalized maghemite nanoparticles, focusing on nanoparticle adsorption to the algal surface and the subsequent magnetic sedimentation of the formed complexes. The combined process of cobalt uptake by algae and secondary binding of magnetic nanoparticles demonstrates a promising and sustainable strategy for heavy metal removal from industrial wastewater. The adsorption capacity of Chlorella vulgaris was assessed, achieving 96 ± 2% Co²⁺ removal, followed by magnetic separation using γ-Fe₂O₃ nanoparticles. The subsequent magnetic separation of the cobalt-adsorbed biomass achieved efficiencies ranging from 57.43% to 97.64% within a 60 s timeframe, demonstrating a significant enhancement over conventional sedimentation methodologies. Stable nanoparticle–biomass binding was facilitated by electrostatic interactions between protonated amine groups on the surface of amine-functionalized maghemite particles and the negatively charged functional groups of the algal cell wall, complemented by the contribution of hydroxyl and carboxyl groups. The even distribution of amine-functionalized maghemite nanoparticles on algal surfaces was further validated by Transmission Electron Microscopy (TEM) imaging, and the strong magnetic properties of the nanoparticles enabled rapid and efficient separation under an external magnetic field. This study underscores the promise of integrating Chlorella vulgaris with amine-functionalized maghemite nanoparticles as a cost-effective, biocompatible, and environmentally sustainable approach for large-scale heavy metal removal from industrial wastewater. Full article

The contamination of aquatic systems by industrial dyes, particularly methylene blue (MB), presents a significant environmental challenge due to their chemical stability and toxicity. In this study, the development and application of a novel magnetic nanohybrid comprising multiwall carbon nanotubes (MWCNTs) functionalized with maghemite (γ-Fe₂O₃) nanoparticles biosynthesized using Eucalyptus globulus extract (denoted MWNT-NPE) is reported. The material was thoroughly characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Vibrating Sample Magnetometer (VSM), and Fourier-Transform Infrared (FTIR) techniques, revealing high crystallinity, mesoporosity, and superparamagnetic behavior. The MWNT-NPE exhibited exceptional MB adsorption performance under optimized conditions (pH 6, 0.8 g L⁻¹ dose, 40 min equilibrium), achieving a maximum adsorption capacity of 92.9 mg g⁻¹. Kinetic analysis indicated chemisorption and physisorption regimes depending on MB concentration, with the pseudo-second-order and Freundlich isotherm models providing the best fits of experimental data. FTIR spectroscopy demonstrated that the removal mechanism involves π–π stacking, hydrogen bonding, and electrostatic interactions between MB molecules and the composite’s surface functional groups. Notably, the magnetic nanohybrid retained over 98% removal efficiency across five regeneration cycles and successfully removed MB from synthetic effluents with efficiencies exceeding 91%. These findings highlight the synergistic adsorption and magnetic recovery capabilities of the bio-functionalized hybrid system, presenting a sustainable, reusable, and scalable solution for industrial dye remediation. Full article

Nanotechnology, specifically magnetic nanoparticles (MNPs), is revolutionizing cancer treatment. Magnetic hyperthermia is a treatment that, using MNPs, can selectively kill cancer cells without causing damage to the surrounding tissues. Background/Objectives: This work aimed to analyze how the synthesis conditions, namely, how the pH of the reaction can influence the magnetic properties of Fe₃O₄ nanoparticles for magnetic hyperthermia, using the hydrothermal synthesis. Methods: For the hydrothermal synthesis, FeCl₃·6H₂O and FeCl₂·4H₂O were mixed with different quantities of NaOH to adjust the pH. After obtaining a black precipitate, the samples were placed in an autoclave at 200 °C for 60 h, followed by a washing and drying phase. The obtained MNPs were analyzed using X-Ray Diffraction (XRD), Transmission Electron Microscopy, a Superconducting Quantum Interference Device, Specific Absorption Rate analysis, and cytotoxicity assays. Results: Different MNPs were analyzed (9.06 < pH < 12.75). The XRD results showed the presence of various iron oxide phases (magnetite, maghemite, and hematite), resulting from the oxidization of the iron phases present in the autoclave. In terms of the average particle size, it was verified that, by increasing the pH value, the size decreases (from 53.53 nm to 9.49 nm). Additionally, MNPs possess a superparamagnetic behaviour with high SAR values (above 69.3 W/g). Conclusions: It was found that the pH of the reaction can influence the size, morphology, magnetization, and thermal efficiency of the MNP. The MNP with the highest composition of Fe₃O₄ was synthesized with a pH of 12.75, with a cubic morphology and a SAR value of 92.7 ± 3.2 W/g. Full article

This study focused on composites of magnetite magnetic nanoparticles (MNP) and poly(lactic acid) (PLA) prepared via sonochemical synthesis. The evaluation of MNP loadings (2, 5, 10, 15, and 20 wt.%) provided insights into the structural and reactivity properties of the materials. Methods used included XRD, FT-IR and Raman spectroscopy, SEM and TEM microscopy, textural and thermal analysis (TG and DTA), and magnetic property measurements. The agreement between theoretical and experimental MNP loadings was good. XRD patterns showed predominantly MNP and semicrystalline phases, with a minor maghemite phase detected by FT-Raman and magnetic measurements. FT-IR analysis revealed interactions between MNP and PLA, confirmed by thermal analysis showing higher transition temperatures for the composites (145 °C) compared to pure PLA (139 °C). FT-Raman spectra also indicated that PLA helps prevent iron oxide oxidation, enhancing nanoparticle stability. SEM and TEM micrographs showed well-dispersed, spherical nanoparticles with minimal agglomeration, dependent on MNP loading. The nanocomposites exhibited low N₂ adsorption, resulting in low surface area (~2.1 m²/g) and porosity (~0.03 cm³/g). Magnetic analysis indicated that in the 2MNP/PLA sample, MNP were in a superparamagnetic-like regime at 300 K, suggesting good dispersion of 2 wt.% MNP in the PLA matrix. Full article

Maghemite (γ-Fe₂O₃) nanoparticles are widely used in biomedical, catalytic, and environmental applications owing to their superparamagnetic properties and surface tunability. Functionalization with primary amine groups via 3-aminopropyltriethoxysilane (APTES) is commonly employed to enable the covalent immobilization of biomolecules and other functional species. The efficiency of this silanization process depends significantly on the density of surface hydroxyl groups, which serve as reactive sites for silane coupling. In this study, the impact of acid and base pretreatments on the surface hydroxylation of γ-Fe₂O₃ nanoparticles and the subsequent APTES grafting performance was systematically evaluated. Intermediate modification using tetraethoxysilane (TEOS) was explored as a strategy to enhance silanization by forming a hydroxyl-rich silica interlayer. Fourier transform infrared spectroscopy and zeta-potential measurements were performed to assess surface chemistry and functional-group incorporation. The results indicate that acid pretreatment significantly increases the availability of reactive –OH groups, while TEOS-assisted silanization improves the uniformity and density of surface-bound amine groups. These findings highlight the critical role of surface conditioning and sequential modification in achieving the controlled and robust amine functionalization of iron oxide nanoparticles. The developed approach provides a foundation for the rational design of surface engineering protocols for high-performance magnetic nanomaterials. Full article

Administration of monocyte-derived dendritic cells (moDCs) sensitized by cancer-associated antigens to the patient is applied to boost the T-cell mediated anti-tumor immune response. Loading moDCs with magnetic nanoparticles (MNPs) and controlling their migration to lymph nodes by an external magnetic field is a way to improve the effectiveness of immunotherapy. In this study, spherical MNPs of maghemite iron oxide with a diameter of about 14 nm were synthesized by laser target evaporation method (LTE) and examined in the context of their prospective use for the needs of moDCs immunotherapy. Characterization of the physicochemical properties of MNPs and their stabilization in physiological media, as well as the magnetic properties of MNPs in the suspensions were considered in detail. The cytotoxic effect of MNPs in growth medium on the human moDCs and MNPs uptake by the cells were also estimated. We show that up-taken MNPs and MNPs in growth medium demonstrated cytotoxic effect only at high concentrations. At the same time, at low concentrations MNPs up-taken by moDCs increased their viability causing the stimulation effect. The evaluation of the quantity of MNPs, up-taken by cells, is possible by magnetometry even for the smallest γ-Fe₂O₃ concentrations. Full article

Nickel-doped iron oxide/graphene oxide powders were synthesized by the co-precipitation method varying the Ni/Fe ratio, and the activity of the materials towards the oxygen reduction reaction in a microbial fuel cell (MFC) was studied. The samples presented X-ray diffraction peaks associated with magnetite, maghemite and Ni ferrite, as well as evidence of hematite. Raman spectra confirmed the presence of maghemite (γ-Fe₂O₃) and NiFe₂O₄. Scanning electron micrographs showed exfoliated sheets decorated with nanoparticles, and transmission electron micrographs showed spherical nanoparticles about 10 nm in diameter well distributed on the individual graphene sheet. The electrocatalytic activity for the oxygen reduction reaction (ORR) was studied by cyclic voltammetry in an air-saturated electrolyte, finding that the best catalyst was the sample with a 1:2 Ni/Fe ratio, using a catalyst concentration of 15 mg·cm⁻² on graphite felt. The 1:2 Ni/Fe catalyst provided an oxygen reduction potential of 397 mV and a maximum oxygen reduction current of −0.13 mA; for comparison, an electrode prepared with GO/γ-Fe₂O₃ showed a maximum ORR of 369 mV and a maximum current of −0.03 mA. Microbial fuel cells with a vertical proton membrane were prepared with Ni-doped Fe₃O₄ and Fe₃O₄/graphene oxide and tested for 24 h; they reached a stable OCV of +400 mV and +300 mV OCV, and an efficiency of 508 mW·m⁻² and 139 mW·m⁻², respectively. The better performance of Ni-doped material was attributed to the combined presence of catalytic activity between γ-Fe₂O₃ and NiFe₂O₄, coupled with lower wettability, which led to better dispersion onto the electrode. Full article

Maghemite nanoparticles (NPs) were successfully developed using phenolic-rich extracts (cyanidin) from Citrus reticulata peel residues. The 11 nm maghemite NPs, obtained at 3% w/v and at 353 K, presented the optimal synthesis conditions. To improve dye adsorption performance, the synergetic adsorption behavior between these 11 nm NPs and multiwall carbon nanotubes was demonstrated. Prior to the adsorption tests, the aging effect on NPs was carefully assessed using various analytical techniques, which clearly showed the magnetite–maghemite phase transition. However, this had no impact on the cyanidin coating or adsorption properties. A remarkable percentage removal of (93 ± 3)% for methylene blue and (84 ± 3)% for methylene green was achieved in short equilibrium times of 10 and 25 min, respectively, with an optimum pH value of 5.5. Reuse experiments revealed that 90% removal for both dyes was achieved between the second to seventh regeneration cycles. Organic loading during these cycles was effectively confirmed by X-ray photoelectron spectroscopy and magnetic measurements. Dye adsorption involves a two-step mechanism: (i) electrostatic adsorption by the negative surface groups of the adsorbent (isoelectric point of 5.2) and the dye cationic groups and (ii) π–π stacking interactions between the aromatic benzene rings of the dyes, the hexagonal skeleton of the multiwall carbon nanotubes, and the phenolic ring groups of the biosynthesized sample. These results suggest that the low-cost modified phenolic adsorbent can be successfully applied to dye removal from water with promising recycling properties. Full article

Maghemite (γ-Fe₂O₃) nanoparticles have attracted considerable interest for electronic applications due to their tunable electrical properties. Doping strategies offer an effective way to optimize their resistive behavior for use in electronic devices. In this study, cobalt (Co) was incorporated into γ-Fe₂O₃ to enhance its resistive properties. X-ray diffraction (XRD) confirmed the retention of the cubic P4₃32 phase, with Co doping inducing subtle lattice distortions due to ionic substitution. Scanning and transmission electron microscopy (SEM/TEM) revealed morphological changes, where Co incorporation influenced particle shape and size distribution. Electrical conductivity analysis demonstrated a decrease in both AC and DC conductivity with the increase in Co content, indicating enhanced resistive behavior. The increase in activation energy suggests a reduction in charge carrier mobility, leading to higher resistivity. Impedance spectroscopy further confirmed increased real and imaginary impedance values, reinforcing the role of Co in suppressing charge transport. These results position cobalt-doped maghemite as a promising material for electronic resistive devices, such as tunable resistors and negative temperature coefficient (NTC) thermistors, where controlled conductivity and stable resistive behavior are essential. Full article