Geometry and Surface Area Optimization in Iron Oxide Nanoparticles for Enhanced Magnetic Properties

Iron oxide nanoparticles (IONPs) are recognized for their potential in biomedical applications due to their distinctive physicochemical properties. This study investigates the synthesis of IONPs with various geometric morphologies-cubic, star-like, truncated icosahedron, and spherical-via thermal decomposition to enhance their utility in magnetic resonance imaging (MRI) and targeted drug delivery. X-ray diffraction analysis verified the Fe3O4 phase in all nanoparticles, illustrating the synthesis's efficacy. Particle morphologies were well-defined, with sizes ranging from 10 to 150 nm, as determined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Magnetic evaluations using a vibrating sample magnetometer (VSM-PPMs) demonstrated their superparamagnetic behavior, with larger particles exhibiting greater saturation magnetization. Notably, truncated icosahedron and cubic IONPs showed superior transverse relaxation rates, with r2 values of 56.77 s1 mM1 and 42.67 s1 mM1, respectively. These results highlight the potential of customizing IONP geometries to optimize their magnetic properties and increase surface area available for functionalization, thereby improving their efficacy for biomedical applications.

Facile synthesis of iron nanoparticles from Camellia Sinensis leaves catalysed for biodiesel synthesis from Azolla filiculoides

Recent years have seen an increase in research on biodiesel, an environmentally benign and renewable fuel alternative for traditional fossil fuels. Biodiesel might become more cost-effective and competitive with diesel if a solid heterogeneous catalyst is used in its production. One way to make biodiesel more affordable and competitive with diesel is to employ a solid heterogeneous catalyst in its manufacturing. Based on X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR), the researchers in this study proved their hypothesis that iron oxide core-shell nanoparticles were generated during the green synthesis of iron-based nanoparticles (FeNPs) from Camellia Sinensis leaves. The fabrication of spherical iron nanoparticles was successfully confirmed using scanning electron microscopy (SEM). As a heterogeneous catalyst, the synthesised catalyst has shown potential in facilitating the conversion of algae oil into biodiesel. With the optimal parameters (0.5 weight percent catalytic load, 1:6 oil-methanol ratio, 60 °C reaction temperature, and 1 h and 30 min reaction duration), a 93.33% yield was attained. This may be due to its acid-base property, chemical stability, stronger metal support interaction. Furthermore, the catalyst was employed for transesterification reactions five times after regeneration with n-hexane washing followed by calcination at 650 °C for 3 h.

Role of Electrolyte pH on Water Oxidation for Iridium Oxides

Understanding the effect of noncovalent interactions of intermediates at the polarized catalyst-electrolyte interface on water oxidation kinetics is key for designing more active and stable electrocatalysts. Here, we combine operando optical spectroscopy, X-ray absorption spectroscopy (XAS), and surface-enhanced infrared absorption spectroscopy (SEIRAS) to probe the effect of noncovalent interactions on the oxygen evolution reaction (OER) activity of IrOx in acidic and alkaline electrolytes. Our results suggest that the active species for the OER (Ir4.x+-*O) binds much stronger in alkaline compared with acid at low coverage, while the repulsive interactions between these species are higher in alkaline electrolytes. These differences are attributed to the larger fraction of water within the cation hydration shell at the interface in alkaline electrolytes compared to acidic electrolytes, which can stabilize oxygenated intermediates and facilitate long-range interactions between them. Quantitative analysis of the state energetics shows that although the *O intermediates bind more strongly than optimal in alkaline electrolytes, the larger repulsive interaction between them results in a significant weakening of *O binding with increasing coverage, leading to similar energetics of active states in acid and alkaline at OER-relevant potentials. By directly probing the electrochemical interface with complementary spectroscopic techniques, our work goes beyond conventional computational descriptors of the OER activity to explain the experimentally observed OER kinetics of IrOx in acidic and alkaline electrolytes.

Nanomedical research and development in Spain: improving the treatment of diseases from the nanoscale

The new and unique possibilities that nanomaterials offer have greatly impacted biomedicine, from the treatment and diagnosis of diseases, to the specific and optimized delivery of therapeutic agents. Technological advances in the synthesis, characterization, standardization, and therapeutic performance of nanoparticles have enabled the approval of several nanomedicines and novel applications. Discoveries continue to rise exponentially in all disease areas, from cancer to neurodegenerative diseases. In Spain, there is a substantial net of researchers involved in the development of nanodiagnostics and nanomedicines. In this review, we summarize the state of the art of nanotechnology, focusing on nanoparticles, for the treatment of diseases in Spain (2017-2022), and give a perspective on the future trends and direction that nanomedicine research is taking.

Biomimetic synthesis of iron oxide nanoparticles from Bacillus megaterium to be used in hyperthermia therapy

The suitable structural characteristics of magnetic nanoparticles have resulted in their widespread use in magnetic hyperthermia therapy. Moreover, they are considered a proper and operational choice for pharmaceutical nanocarriers. Using the biomimetic method, we were able to produce iron oxide magnetic nanoparticles from the bacterial source of PTCC1250, Bacillus megaterium, for therangostic diagnosis systems and targeted drug delivery. Some of the benefits of this method include mitigated environmental and biological dangers, low toxicity, high biocompatibility, cheap and short-term mass production possibilities in each synthesis round compared to other biological sources, simple equipment required for the synthesis; and the possibility of industrial-scale production. Bacillus megaterium is a magnetotactic bacteria (MTB) that has a magnetosome organelle capable of orienting based on external magnetic fields, caused by the mineralization of magnetic nanocrystals. Utilizing this capability and adding an iron nitrate solution to the bacterial suspension, we synthesized iron oxide nanoparticles. The extent of synthesis was measured using UV–visible spectrophotometry. The morphology was evaluated using FESEM. The crystallized structure was characterized using RAMAN and XRD. The size and distribution of the nanoparticles were assessed using DLS. The surface charge of the nanoparticles was measured using zeta potential. The synthesis of iron oxide nanoparticles was confirmed using FT-IR, and the magnetic property was measured using VSM. This study is continued to identify industrial and clinical applications.

Anti-metastatic breast cancer potential of novel nanocomplexes of diethyldithiocarbamate and green chemically synthesized iron oxide nanoparticles

Mortality rate of metastatic breast cancer is linked to cancer stem cells (CSCs)' aggressive features (chemoresistance to apoptosis and redox imbalance). Therefore, unique dual therapeutic strategy compacts CSCs with inducing oxidative stress-mediated nonapoptosis (ferroptosis), confers effective malignant tumor eradication. Diethyldithiocarbamate (DDC) is a potent inhibitor of CSC aldehyde dehydrogenase and lowers glutathione (GSH) which aggravate iron-dependent ferroptosis. Herein, nanoformulations of DDC with green chemically synthesized ferrous oxide nanoparticles (FeO NPs) and ferric oxide (Fe₂O₃ NPs) were prepared. Due to nanoparticle characters and synergistic effect between iron oxide NPs and DDC, nanocomplexes (DFeO NPs and DFe₂O₃ NPs, respectively) exhibited the strongest anti-metastatic cancer potency in vitro. Because of corresponding iron oxide nature, DFeO NPs demonstrated better therapeutic efficacy than DFe₄O₃ NPs, in mammary tumor liver metastasis-bearing mice, in terms of tumor size, histological analysis, immunostaining % of ki-67⁺ and caspase 3⁺, and gene expression of p53 and BCl2. The potent anti-tumor effect of DFeO nanocomplex is attributed to the maximum elevation of reactive oxygen species and lipid peroxidation (ferroptosis hall marker) with severe depletion of GSH and Nrf2 selectively in both tumor tissues, causing CSC eradication with halting metastatic activity. The latters were confirmed by lowering CD44⁺ % and gene expression of HIF-α, β-catenin, Notch, ABCG2-mediated chemoresistance, and MMP9 with diminishing liver tumor marker. Moreover, this nanocomplex did not cause any abnormal alterations in histological and biochemical parameters, compared to healthy group. Therefore, the selective apoptotic and ferroptotic with anti-CSC effects of DFeO NPs open new safe avenue for metastatic tumor therapy.

A critical review of the development and demulsification processes applied for oil recovery from oil in water emulsions

The formation of stable emulsions is a fundamental problem in oil industry that can result in a sequence of environmental and operational problems. Chemical demulsification is extensively applied for the recovery of oil from water as well as water from oil. This review introduces different chemical demulsifiers applied for the demulsification and recovery of oil from oil in water (O/W) emulsions. Main types of surfactants (anionic, cationic, nonionics and amphoteric) involved in the formation of emulsions and enhances their stability were discussed. Promising demulsifiers such as nanoparticle (NP), hyperbranched polymers, and ionic liquids (IL), which achieved high oil recovery rate, parameters influencing demulsification efficiency and demulsification mechanisms were explored. Lastly, improvements, challenges, and new changes being made to chemical demulsifiers were underlined. Functionalized magnetic nanoparticles and hyperbranched polymers were very effective in recovering oil from O/W emulsions with an efficiency >95%. Polymers with highly hydrophilic content and high molecular weight can achieve excellent oil recovery rates due to higher interfacial activity, higher dispersion, and presence of specific functional groups. Although ionic liquids could achieve oil recovery up to 90%, high cost limits their applications. NPs showed excellent oil recovery behavior at low concentrations and ambient temperature. Demulsification efficiency of NPs can be enhanced by functionalize with other components (e.g., polymers and surfactants), while service life can be extend by silica coating. Future challenges include scaling up the use of NPs in oil recovery process and highlighting contrasts between lab-scale and field-scale applications.

Understanding Pore Surface Modification of Sucrose-Modified Iron Oxide/Silica Mesoporous Composite for Degradation of Methylene Blue

Santa Barbara Amorphous (SBA-15) containing iron oxide with a sucrose-modified in a heterogeneous reaction for degradation methylene blue (MB) successful synthesized used hydrothermal, ultrasonication, and wet impregnation method. SBA-15 is mesoporous silica that can easily serve as external and internal surfaces making it suitable for a wide range of applications. The structure and morphology of materials were characterized using Surface Area Analyzer (SAA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Transmission Electron Microscopy (TEM). Iron oxide impregnated as a maghemite phase has an average size of 12 nm and well distributed on the SBA-15. After modified with sucrose the materials remaining stable, which has a two-dimensional hexagonal (p6mm) structure, high specific surface area, and large pore volume (up to 1.82 cm3.g−1). The degradation of MB was evaluated under visible light irradiation using UV-Vis spectroscopy. Catalytic activity showed efficiencies of 52.9; 70.2; and 21.1% for SBA-15, Fe2O3/SBA-15, and sucrose-modified Fe2O3/SBA-15 respectively. Sucrose-modified Fe2O3/SBA-15 has the lowest efficiency, which probably occurs due to the presence of pore-blocking and the formation of micropores on the external pore. The modification with sucrose has the advantage of producing a high surface area even though there is a catalytic center due to partial decomposition which causes a decrease in the efficiency of degradation of MB. All materials provide a high micro surface area so that they can be further adapted and can be widely applied to many potential applications as both catalyst support and an adsorbent. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Thermal and anticorrosion properties of polyurethane coatings derived from recycled polyethylene terephthalate and palm olein-based polyols

Polyols of palm olein/polyethylene terephthalate (PET) were synthesized by means of incorporating recycled PET from waste drinking bottles in different proportions into palm olein alkyd in the presence of ethylene glycol. The polyols were characterized by FTIR, and theirs hydroxyl value (OHV), acid value (AV) and viscosity were determined. The formulation of the polyurethane coating was carried out by dissolving the polyol in mixed solvent of cyclohexanone/tetrahydrofuran (THF) (4 : 1) followed by reacting 1 hydroxyl equivalent of the polyol with 1.2 equivalents of methylene diphenyldiisocyanate and 0.05% dibutyltin dilaurate (DBTDL) catalyst. The coating cured through the cross-linking reactions between hydroxyl and isocyanate groups. The formation of urethane linkages was established by FTIR spectroscopy. The set films were characterized by thermal analysis. To study their anticorrosion properties, polarization measurements and EIS in 3.5% NaCl solution were determined. The coatings displayed good thermal stability and anticorrosion properties which were supported by XRD analysis. The PU7 coating, with the highest proportion of PET (up to 15% w/w), displayed significantly improved thermal stability and anticorrosion properties. It is evident that the performance of the polyurethane (PU) coatings could be enhanced by the incorporation of PET.

Preparation of immunomagnetic beads coupled with a rhodamine hydrazine immunosensor for the detection of Mycobacterium avium subspecies paratuberculosis in bovine feces, milk, and colostrum

The aim of this study was to develop and evaluate a method for detecting Mycobacterium avium ssp. paratuberculosis (MAP) bacteria in bovine fecal, milk, and colostrum samples using immunomagnetic beads (IMB) and a rhodamine hydrazone immunosensor. Immunomagnetic beads were prepared by using purified antibodies from hyperimmunized sera that were coupled to Fe nanoparticles with diethylene triamine pentaacetic acid (DTPA) or ethyl (dimethyl aminopropyl) carbodiimide (EDC)-N-hydroxy succinimide (NHS) as linkers. Rhodamine hydrazone particles were synthesized and coupled to IgY anti-MAP antibodies using DTPA or EDC-NHS linkers. Separation efficiency of the IMB was tested on bovine fecal, milk, and colostrum samples experimentally contaminated with MAP. The studied methods were evaluated on their ability to detect MAP and separate bacteria in complex mediums. The ELISA results indicated 95% efficacy in antibody coupling to IMB, with the DTPA-IMB method being more efficient than the EDC-NHS-IMB method. By using the DTPA-IMB method, MAP bacteria were successfully recovered from fecal, milk, and colostrum samples. The DTPA-IMB method used in combination with the rhodamine hydrazone immunosensor had a limit of detection equal to 30 and 30,000 MAP cells/mL using chromogenic and fluorescent properties, respectively. Combining the DTPA-IMB separation method with the rhodamine hydrazone immunosensor provides a fast, sensitive, and cost-beneficial method for detecting MAP in bovine feces, milk, and colostrum.

A review of green methods for phyto-fabrication of hematite (α-Fe2O3) nanoparticles and their characterization, properties, and applications

The aim of the current work is the introduction of a quick and simple literature survey about the bio-fabrication of the Alpha Hematite nanoparticles (α-Fe₂O₃) using the plant extracts green method. The survey manifested the utilities of the environmentally friendly biosynthesis methods via extracting different plant species, some of its important physicochemical properties, various instrumental analysis characterization tools, and potential applications.

Facile synthesis of superparamagnetic Fe3O4@noble metal core-shell nanoparticles by thermal decomposition and hydrothermal methods: comparative study and catalytic applications

Herein, we report on developing a facile synthetic route for reusable nanocatalysts based on a combination of the supermagnetic properties of magnetite with the unique optical and catalytic properties of noble metal hybrid nanomaterials. We compare two different synthetic methods, to find out which is best from synthetic and application points of view, for the synthesis of Fe₃O₄ and Fe₃O₄@M (M = Ag or Au) core-shell hybrid nanostructures. The two different single-step synthetic methods are: thermal decomposition and hydrothermal. The structural, morphological and magnetic properties of the obtained Fe₃O₄ and Fe₃O₄@M nanoparticles were characterized by various techniques. XRD of the Fe₃O₄ nanoparticles exhibited sharp and strong diffraction peaks, confirming the highly crystalline structure of the Fe₃O₄ particles synthesized by the hydrothermal method, while broad and weak peaks were observed on using the thermal decomposition method. Both Fe₃O₄@Ag and Fe₃O₄@Au core-shells obtained by the hydrothermal method showed the reflection planes of Fe₃O₄ and additional planes of Ag or Au. But on the formation of Fe₃O₄@Ag/Au by the thermal decomposition method the peak for Fe₃O₄ disappeared and only the diffraction peaks of Ag or Au appeared. According to TEM analysis there was a broad particle-size distribution, random near-spherical shapes and slight particle agglomeration for Fe₃O₄ synthesized by the thermal decomposition method. However, there was a moderate size distribution, spherical shapes and well-dispersed particles without large aggregations for the hydrothermal method. TEM images of the synthesized nanoparticles by the two methods used showed a pronounced difference in both size and morphological shape. The catalytic performance of the synthesized nanoparticles was examined for the reduction of Congo red dye in the presence of NaBH₄. The Fe₃O₄ nanocatalyst maintained its catalytic activity for only one cycle. In the cases of Fe₃O₄@Au and Fe₃O₄@Ag, the catalytic activity was conserved for four and ten successive cycles, respectively. Based on the obtained results, it was concluded that the hydrothermal synthesis of Fe₃O₄, Fe₃O₄@Ag and Fe₃O₄@Au nanostructures is highly recommended due to their selectivity and merits.

New Synthetic Route for the Growth of α-FeOOH/NH2-Mil-101 Films on Copper Foil for High Surface Area Electrodes

A novel metal organic framework (MOF)-based composite was synthesized on a Cu substrate via a two-step route. An amorphous iron oxide/hydroxide layer was first deposited on a Cu foil through a sol-gel process; then, Fe-NH₂-Mil-101 was grown using both the iron oxide/hydroxide matrix, which provided the Fe³⁺ centers needed for MOF formation, and 2-aminoterephthalic acid ethanol solution. This innovative synthetic strategy is a convenient approach to grow metal oxide/hydroxide and MOF composite films. Structural, chemical, and morphological characterizations suggest that the obtained composite is made up of both the α-FeOOH goethite and the NH₂-Mil-101 phases featuring a hybrid heterostructure. The electrochemical features of the composite structure were investigated using electrochemical impedance spectroscopy. The impedance behavior of the α-FeOOH/NH₂-Mil-101 films indicates that they can be used as efficient high surface area metal hydroxide/MOF-based electrodes for applications such as energy storage and sensing.

Magneto-Optical Characteristics of Streptavidin-Coated Fe3O4@Au Core-Shell Nanoparticles for Potential Applications on Biomedical Assays

Recently, gold-coated magnetic nanoparticles have drawn the interest of researchers due to their unique magneto-plasmonic characteristics. Previous research has found that the magneto-optical Faraday effect of gold-coated magnetic nanoparticles can be effectively enhanced because of the surface plasmon resonance of the gold shell. Furthermore, gold-coated magnetic nanoparticles are ideal for biomedical applications because of their high stability and biocompatibility. In this work, we synthesized Fe₃O₄@Au core-shell nanoparticles and coated streptavidin (STA) on the surface. Streptavidin is a protein which can selectively bind to biotin with a strong affinity. STA is widely used in biotechnology research including enzyme-linked immunosorbent assay (ELISA), time-resolved immunofluorescence (TRFIA), biosensors, and targeted pharmaceuticals. The Faraday magneto-optical characteristics of the biofunctionalized Fe₃O₄@Au nanoparticles were measured and studied. We showed that the streptavidin-coated Fe₃O₄@Au nanoparticles still possessed the enhanced magneto-optical Faraday effect. As a result, the possibility of using biofunctionalized Fe₃O₄@Au nanoparticles for magneto-optical biomedical assays should be explored.

Mechanism and kinetics of magnetite oxidation under hydrothermal conditions

The stability of magnetite under oxidizing hydrothermal conditions was evaluated at temperatures of 120, 150, 180 and 275 °C. A well-characterized sample of commercially-available magnetite with a particle size of approximately 690 nm was oxidized by dissolved oxygen (DO) under alkaline hydrothermal conditions in titanium autoclaves. In these trials, the DO was always in equilibrium with the gas phase oxygen that was air-derived and was located above the hydrothermal solution, which contained ammonium hydroxide at a pH_{25 °C} of approximately 9.5. Samples recovered by filtration were analysed by X-ray diffraction and scanning electron microscopy, while Fe(ii)/Fe ratios were determined by titration in conjunction with spectrophotometry. Oxidation between 120 and 180 °C was found to generate high concentrations of maghemite and hematite in the product, with the latter compound having either a hexagonal bipyramidal or rhombohedral morphology. The oxidation kinetics was consistent with a diffusion controlled process. The reaction probably proceeded via the outward diffusion of ferrous ions from the magnetite, forming a magnetite/maghemite core/shell structure in conjunction with the dissolution of maghemite and reprecipitation of hematite. Oxidation at 275 °C presented different characteristics from those observed at the lower temperatures. Negligible amounts of maghemite were found, and the primary oxidation product was hematite with no specific morphologies. Moreover, the kinetics was slower than at 180 °C. This unexpected temperature effect is attributed to the rapid growth, at 275 °C, of a dense layer of hematite on the surface of the magnetite that impeded the oxidation of magnetite.

Oxidation kinetics of magnetite into hematite depends on temperature and morphology of the ferric oxide phase.

Green synthesis and characterization of novel 1,2,4,5-tetrasubstituted imidazole derivatives with eco-friendly red brick clay as efficacious catalyst

Use of cheaper and recyclable materials contributes positively to economic growth with environmental sustainability. We report the prospect of utilizing red brick clay as catalyst, which exhibited excellent activity in rapid one-pot four-component condensation of 1,2,4,5-tetrasubstituted imidazoles with high conversion and yields (91-96%) in aqueous medium at 60 °C in short reaction times (25-40 min). The red brick clay material was fully characterized by XRD, FT-IR, SEM, TEM, EDX and BET analyses. Red brick clay consisted of oxides of Si (20.38%), Fe (19.55%), Al (14.30%) and minor amounts of Ca (3.60%) and Mg (1.68%). The slate-like-shaped structure morphology and flaky appearance of inexpensive solid clay material proved competent material for the synthesis of 15 novel 1,2,4,5-tetrasubstituted imidazole derivatives. In addition, the advantages of the eco-friendly method are non-toxicity and re-usability of the catalyst. Reaction offers 78% atom economy and 84% carbon capture.

Surface Modification of Magnetic Iron Oxide Nanoparticles

Functionalized iron oxide nanoparticles (IONPs) are of great interest due to wide range applications, especially in nanomedicine. However, they face challenges preventing their further applications such as rapid agglomeration, oxidation, etc. Appropriate surface modification of IONPs can conquer these barriers with improved physicochemical properties. This review summarizes recent advances in the surface modification of IONPs with small organic molecules, polymers and inorganic materials. The preparation methods, mechanisms and applications of surface-modified IONPs with different materials are discussed. Finally, the technical barriers of IONPs and their limitations in practical applications are pointed out, and the development trends and prospects are discussed.

Biosynthesized iron oxide nanoparticles used for optimized removal of cadmium with response surface methodology

To effectively reuse adsorbent in removal of Cd (II), magnetic modification was considered as an alternative. In this study, iron oxide nanoparticles (IONPs) synthesized from the extract of Excoecaria cochinchinensis Lour leaves were modified by low-temperature calcination, and used to remove Cd (II). Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and magnetic properties analysis confirmed the successful synthesis of nanoscale magnetic FeOC composite. Response surface methodology (RSM) served to optimize the adsorption of Cd (II) by IONPs based on Box-Behnken design (BBD). According to the quadratic model, the effect of each factor on the removal of Cd (II) by IONPs was: pH > dosage > ionic strength > temperature. In percentage terms, 98.50% of Cd (II) (10 mg L^-1) was removed when the pH, absorbent dosage, temperature and ionic strength conditions were 8.07, 2.5 g L^-1, 45 °C, and 0.07 mol L^-1, respectively. The adsorption of Cd (II) by IONPs is consistent with pseudo-second order kinetics and Langmuir adsorption isotherm models, indicating that the process of adsorption of Cd (II) by IONPs belongs to monolayer chemical adsorption. The -COOH, -COH, Cπ electron and ≡FeOH may be the binding sites for Cd (II) on the surface of IONPs. Overall, IONPs can be used to remove Cd (II) effectively from aqueous solution in a wide range of conditions.

An Aspergillus aculateus strain was capable of producing agriculturally useful nanoparticles via bioremediation of iron ore tailings

Mining waste such as iron ore tailing is environmentally hazardous, encouraging researchers to develop effective bioremediation technologies. Among the microbial isolates collected from iron ore tailings, Aspergillus aculeatus (strain T6) showed good leaching efficiency and produced iron-containing nanoparticles under ambient conditions. This strain can convert iron ore tailing waste into agriculturally useful nanoparticles. Fourier-transform Infrared Spectroscopy (FT-IR analysis) established the at the particles are protein coated, with energy dispersive X-ray Spectroscopy (EDX analysis) showing strong signals for iron. Transmission Electron Microscopy (TEM analysis) showed semi-quasi spherical particles having average size of 15 ± 5 nm. These biosynthesized nanoparticles when tested for their efficacy on seed emergence activity of mungbean (Vigna radiata) seeds, and enhanced plant growth at 10 and 20 ppm.

Synthesis of TiO2@α-Fe2O3 core–shell heteronanostructures by thermal decomposition approach and their application towards sunlight-driven photodegradation of rhodamine B

TiO₂@α-Fe₂O₃ core–shell heteronanostructures that act as a good photocatalyst for the degradation of RhB were synthesized by a novel thermal decomposition approach.

In Situ Atomic-Scale Probing of the Reduction Dynamics of Two-Dimensional Fe2O3 Nanostructures

Atomic-scale structural dynamics and phase transformation pathways were probed, in situ, during the hydrogen-induced reduction of Fe₂O₃ nanostructure bicrystals using an environmental transmission electron microscope. Reduction commenced with the α-Fe₂O₃ → γ-Fe₂O₃ phase transformation of one part of the bicrystal, resulting in the formation of a two-phase structure of α-Fe₂O₃ and γ-Fe₂O₃. The progression of the phase transformation into the other half of the bicrystalline Fe₂O₃ across the bicrystalline boundary led to the formation of a single-crystal phase of γ-Fe₂O₃ with concomitant oxygen-vacancy ordering on every third {422} plane, followed by transformation into Fe₃O₄. Further reduction resulted in the coexistence of Fe₃O₄, FeO, and Fe via the transformation pathway Fe₃O₄ → FeO → Fe. The series of phase transformations was accompanied by the formation of a Swiss-cheese-like structure, induced by the significant volume shrinkage occurring upon reduction. These results elucidated the atomistic mechanism of the reduction of Fe oxides and demonstrated formation of hybrid structures of Fe oxides via tuning the phase transformation pathway.

p-Phosphonated Calix[n]arene Stabilizes Superparamagnetic Nanoparticles for Nitrate and Phosphate Uptake

Highly faceted superparamagnetic magnetite nanoparticles roughly 11 nm in diameter are readily accessible in the presence of p-phosphonated calix[n]arenes of different ring sizes (n=4, 5 and 6), through the use of a simple co-precipitation technique. In contrast, the larger calix[8]arene affords spherical particles of comparable size. The maximum magnetization is 70-60 emu g^-1 , which decreases with increasing size of the calixarene macrocycle, and the evidence indicates that the calixarenes bind to the surface of the nanoparticles via the phosphonate head groups rather than the phenolic oxygen centers. The stabilized nanoparticles show dual functionality: they remove up to 62 % of nitrate nitrogen and 48 % of phosphate from an aqueous effluent after 24 hours at concentrations of only 1 g L^-1 of calixarene-coated nanoparticles.

Assessing the hyperthermic properties of magnetic heterostructures: the case of gold-iron oxide composites

Gold-iron oxide composites were obtained by in situ reduction of an Au(III) precursor by an organic reductant (either potassium citrate or tiopronin) in a dispersion of preformed iron oxide ultrasmall magnetic (USM) nanoparticles. X-ray diffraction, transmission electron microscopy, chemical analysis and mid-infrared spectroscopy show the successful deposition of gold domains on the preformed magnetic nanoparticles, and the occurrence of either citrate or tiopronin as surface coating. The potential of the USM@Au nanoheterostructures as heat mediators for therapy through magnetic fluid hyperthermia was determined by calorimetric measurements under sample irradiation by an alternating magnetic field with intensity and frequency within the safe values for biomedical use. The USM@Au composites showed to be active heat mediators for magnetic fluid hyperthermia, leading to a rapid increase in temperature under exposure to an alternating magnetic field even under the very mild experimental conditions adopted, and their potential was assessed by determining their specific absorption rate (SAR) and compared with the pure iron oxide nanoparticles. Calorimetric investigation of the synthesized nanostructures enabled us to point out the effect of different experimental conditions on the SAR value, which is to date the parameter used for the assessment of the hyperthermic efficiency.

Facile biosurfactant assisted biocompatible α-Fe2O3 nanorods and nanospheres synthesis, magneto physicochemical characteristics and their enhanced biomolecules sensing ability

Tunable magnetic and electrocatalytic characteristics of α-Fe₂O₃ nanostructures were fabricated by tapping saponin induced anisotropic growth, demonstrated excellent electrocatalytic activity towards dopamine and uric acid with wider potential gap.

Alkali metal ion induced cube shaped mesoporous hematite particles for improved magnetic properties and efficient degradation of water pollutants

Alkali metal ion induced cube shaped mesoporous α-Fe₂O₃particles showed improved magnetic properties and efficient photo-Fenton degradation of methylene blue.

Super-Paramagnetic Nanoparticles with Spinel Structure: A Review of Synthesis and Biomedical Applications

The study of ceramic materials has attracted the attention of many researchers due to the possibility of their use in nanotechnology. The spinel ferrites form a large group of materials with a broad range of applications. Some examples include electronic devices such as high-frequency transformer cores, antenna rods, induction-tuners, among many others. However, when the ferritic materials display superparamagnetic behavior, their potential for biological applications like drug delivery, hyperthermia, resonance magnetic imaging and magnetic separation, become amazingly high. Therefore, the superparamagnetism is a characteristic strongly desired for spinel ferrites. Since this phenomenon is size-dependent, the methodologies to synthesize these materials has emerged as a crucial step in order to obtain the desired properties. In this regarding, several synthetic processes have been developed. For example, co-precipitation is a fast and cheap method to synthesize superparamagnetic spinel ferrites. However, methodologies involving microwave, ultrasound or polymers frequently result in these kind of materials. Therefore, this review brings a brief historic introduction about spinel ferrites as well as essential concepts to understand their structure and magnetic properties. In addition to this, recent advances in synthesis and applications of the superparamagnetic spinel ferrites are mentioned. Contents of Paper

Preparation and Characterization of Magnetite Nanoparticles

The preparation of magnetite nanoparticles with controlled size has attracted of scientific and technological broad attention. Spherical magnetite nanoparticles in the size range from 8nm to 22 nm were synthesized by coprecipiation method using hexadecyl trimethyl ammonium bromide (CTAB) as dispersant. Magnetite nanoparticles have good dispersibility and uniform particles size distribution. The properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), automated surface area and pore size analyzer, vibrating sample magnetometer (VSM) and the catalytic performance was measured using high performance liquid chromatography (HPLC). The saturation magnetization is 13.785emu/g, and the coercive force of the sample is 23.738G, the average size of the particles is 13.6 nm, specific surface area is 19.318 m2/g and phenol conversion is up to 99.5%. These results indicate the synthesized magnetite particles have good performance.

Enhanced magnetism in highly ordered magnetite nanoparticle-filled nanohole arrays

A new approach to develop highly ordered magnetite (Fe3O4) nanoparticle-patterned nanohole arrays with desirable magnetic properties for a variety of technological applications is presented. In this work, the sub-100 nm nanohole arrays are successfully fabricated from a pre-ceramic polymer mold using spin-on nanoprinting (SNAP). These nanoholes a then filled with monodispersed, spherical Fe3O4 nanoparticles of about 10 nm diameter using a novel magnetic drag and drop procedure. The nanohole arrays filled with magnetic nanoparticles a imaged using magnetic force microscopy (MFM). Magnetometry and MFM measurements reveal room temperature ferromagnetism in the Fe3O4-filled nanohole arrays, while the as-synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior. As revealed by MFM measurements, the enhanced magnetism in the Fe3O4-filled nanohole arrays originates mainly from the enhanced magnetic dipole interactions of Fe3 O4 nanoparticles within the nanoholes and between adjacent nanoholes. Nanoparticle filled nanohole arrays can be highly beneficial in magnetic data storage and other applications such as microwave devices and biosensor arrays that require tunable and anisotropic magnetic properties.

Engineered magnetic nanoparticles for biomedical applications

In the past decades, magnetic nanoparticles (MNPs) have been used in wide range of diverse applications, ranging from separation to sensing. Here, synthesis and applications of functionalized MNPs in the biomedical field are discussed, in particular in drug delivery, imaging, and cancer therapy, highlighting also recent progresses in the development of multifunctional and stimuli-responsive MNPs. The role of their size, composition, and surface functionalization is analyzed, together with their biocompatibility issues.

Facile synthesis of pseudo-peanut shaped hematite iron oxide nano-particles and their promising ethanol and formaldehyde sensing characteristics

Herein, pseudo-peanut shaped hematite iron oxide nano-particles are prepared through a facile cost effective wet chemical synthesis route.