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The utilization of nanoparticles to enhance bacterial activity and boost hydrogen production in fermentation processes has gained significant attention due to their unique properties such as high specific surface area and quantum size. This research aimed to improve the biohydrogen yield from food waste by adding iron oxide nanoparticles (Fe 3 O 4) at various concentrations (50, 75, 100, 150, and 200 mg/l) and titanium dioxide (TiO 2) at different amounts (25–150 mg/l) to a single-stage hybrid (dark/photo) fermentation reactor. After obtaining the optimal amount of these two nanoparticles, the effect of synergic addition of nanoparticles on hydrogen production yield, was investigated at ratios of Fe 3 O 4 /TiO 2 = 50/50 and 100/50 mg/mg. At the ratio of Fe 3 O 4 /TiO 2 = 100/50, the cumulative hydrogen production and yield of hydrogen have increased from 1613 to 3392 ml and 101.60 to 213.66 mlH 2 /gVS, respectively, compared to the control experiment. We also found that the COD removal rate has enhanced from 28% to 40.1%. In the optimal value, the bacterial growth lag phase has also remarkably decreased from 8.19 to 4.81 h. • Synergic application of TiO 2 and Fe 3 O 4 significantly increased biohydrogen purity and production yield. • TiO 2 played an important role in the activity of bacteria in the photo fermentation process. • Fe 3 O 4 played an important role in the dark fermentation system. • Nanoparticles may act as a scaffold for enzyme and substrate binding. • Optimal nanoparticle concentration may differ for different bioreactors. [ABSTRACT FROM AUTHOR]

[Display omitted] • α-Fe 2 O 3 was evaluated as anode of solid-state batteries using oxide electrolyte. • Smaller Fe 2 O 3 particles showed better anode performance. • Contact area between Fe 2 O 3 and the electrolyte was increased to improve performance. • Fe 2 O 3 anode operated for the first time in oxide-based solid-state Li batteries. As Li-ion battery anode materials, two types of hematite (Fe 2 O 3 (big), Fe 2 O 3 (ultrafine)) were evaluated by using liquid electrolyte and oxide-based solid electrolyte. Although the anode using Fe 2 O 3 (ultrafine) with larger specific surface area showed a high initial reversible capacity in the liquid-electrolyte cell, there was a steep capacity decay in the cycling test. In the solid-electrolyte cell, we obtained very low reversible capacities of 40 mA h g−1 for the anode using Fe 2 O 3 (big) with smaller specific surface area. In contrast, the capacity of Fe 2 O 3 (ultrafine) anode was as high as 400 mA h g−1 at the 20th cycle. This is the first demonstration of charge–discharge reactions for Fe 2 O 3 anode in oxide-based solid-state batteries. The Fe 2 O 3 (ultrafine) particles were dispersed relatively uniformly between solid electrolyte in the active layer, suggesting that the contact area between Fe 2 O 3 and solid electrolyte becomes large. Consequently, Fe 2 O 3 (ultrafine) could benefit from larger contact area delivering the suitable reaction site for Li+ to improve the anode performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • VFAs can be obtained from an aqueous solution derived by the fermentation of food waste; • Their recovery is pivotal for economic and environmental reasons; • Iron oxide NPs with functionalization or not showed low reproducible results; • Liquid-liquid extraction can be used showing higher efficiency; • the use of oleic acid presented extraction capacity up to 97% and good reproducibility. The extraction of volatile fatty acids (VFAs) from an aqueous solution derived by fermentation of food waste is a key challenge in the context of the circular economy, thanks to their high economic and environmental impact due to their wide-ranging use in various industrial fields. In this work, we compared two different extraction methods: one novel and one classical. Firstly, iron oxide nanoparticles of around 10 nm were prepared and used as they are or functionalised using (3-Aminopropyl)triethoxysilane) (APTES) molecules, adipic acid and oleic acid. This was compared with a traditional industrial method (liquid–liquid extraction) that can guarantee high extraction of VFAs with high reproducibility. Indeed the use of dichloromethane, hexane, methyl tert -butyl ether and oleic acid presented extraction values of up to 30 % while iron oxide NPs showed results with low reproducibility. The comparison demonstrated the use of oleic acid as a promising solvent for liquid–liquid extraction of VFAs. [ABSTRACT FROM AUTHOR]

Inorganic nanoparticles provide multipurpose platforms for a broad range of delivery applications. Intrinsic nanoscopic properties provide access to unique magnetic and optical properties. Equally importantly, the structural and functional diversity of gold, silica, iron oxide, and lanthanide-based nanocarriers provide unrivalled control of nanostructural properties for effective transport of therapeutic cargos, overcoming biobarriers on the cellular and organismal level. Taken together, inorganic nanoparticles provide a key addition to the arsenal of delivery vectors for fighting disease and improving human health. Unlabelled Image [ABSTRACT FROM AUTHOR]

[Display omitted] • T. indica fruit extract-based Fe 2 O 3 NPs (T. indica -Fe 2 O 3 NPs) were synthesized and characterized. • T. indica -Fe 2 O 3 NPs have shown significant antibacterial effects. • T. indica -Fe 2 O 3 NPs have shown significant antibiofilm effects. • T. indica -Fe 2 O 3 NPs have shown DPPH radical scavenging activity. In this investigation, T. indica fruit extract was used to phyto-synthesize T. indica -Fe 2 O 3 NPs and then they were characterized by bio-physical techniques. The formation of T. indica -Fe 2 O 3 NPs was checked by the development of black colour precipitate. A sharp peak was noticed at 400 nm for T. indica -Fe 2 O 3 NPs by UV–Vis spectroscopy. The different XRD peaks denotes the hexagonal shape of T. indica -Fe 2 O 3 NPs and the size of crystallite was 19.8 nm. The role of phytochemicals in the plant extract during NPs synthesis was confirmed by FTIR spectra. The existence of polyhedral shaped NPs measuring 28 nm was noticed through SEM analysis. EDX spectra recorded the weight (%) of elemental iron was 77.91%. The agar well diffusion assay revealed that the prepared T. indica -Fe 2 O 3 NPs showed greater inhibition of E. faecalis and S. aureus (Gram-positive) than K. pneumoniae and E. coli (Gram-negative) at 25 to 100 µg mL−1. Biofilm inhibition of test bacteria and fungi was noted. DPPH scavenging was increased to 71.1% at 100 μg mL−1. This investigation arrives the fact that T. indica -Fe 2 O 3 NPs has the potential to treat bacterial infections and could be employed as a substitute to conventional therapeutic agent in biomedical sector in the future. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Magnetic nanomaterials were formed by pulsed laser ablation of iron in water and air. • Material ablated in water contained spherical particles of Fe 3 O 4 , Fe 2 O 3 , FeO and Fe. • Material ablated in air contained more Fe 3 O 4 and nitrogen (N-O, N-H or FeN x) • The surface composition and electrokinetic properties of the materials differed. • Material obtained in air is more stable in colloids due to its surface composition. Abstract Magnetic nanomaterials were synthesized using a method of pulsed laser ablation of an iron target in water (PLAL) and in air (PLAG). The microstructure and composition of the obtained materials differed. Spherical nanoparticles (NPs) of 2–80 nm containing Fe 3 O 4 , α-Fe 2 O 3 , γ-Fe 2 O 3 , FeO and Fe were obtained using PLAL. According to the XPS and FTIR data, the surfaces of these particles contained both Fe 3 O 4 and Fe 2 O 3. PLAG led to the formation of NPs of 2–120 nm and 2-D lamellar structures up to 1 μm. This material contained more magnetite and nitrogen species, presumably iron nitrides. This material's surface contained FeOOH; the OH-group content was very high. It exhibited the greatest sedimentation stability and zeta potential value, while magnetic NPs (MNPs) obtained in water were less stable in colloids. The difference in the magnetic parameters of the two materials can be connected to not only the different composition (different magnetite content and nitrogen species presence) but also their structural features. Thus, PLAL and PLAG methods allowed for obtaining magnetic nanostructured materials with different characteristics suitable for application in different fields. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The engineering of iron oxide nanoparticles (IONPs) for biomedical use has received great interest over the past decade. In the present study we investigated the biocompatibility of IONPs grafted with linear (2P) or generation 1 (2PG1) or 2 (2PG2) dendronized oligoethyleneglycol units in THP-1-derived macrophages. To evaluate IONP effects on cell functionality and homeostasis, mitochondrial function (MTT assay), membrane permeability (LDH release), inflammation (IL-8), oxidative stress (reduced glutathione, GSH), NLRP3 inflammasome activation (IL-1β) and nanoparticle cellular uptake (intracellular iron content) were quantified after a 4-h or 24-h cell exposure to increasing IONP concentrations (0–300 µg Fe/mL). IONPs coated with a linear molecule, NP10COP@2P, were highly taken up by cells and induced significant dose-dependent IL-8 release, oxidative stress and NLRP3 inflammasome activation. In comparison, IONPs coated with dendrons of generation 1 (NP10COP@2PG1) and 2 (NP10COP@2PG2) exhibited better biocompatibility. Effect of the dendritic architecture of the surface coating was investigated in a kinetic experiment involving cell short-term exposure (30 min or 1 h 30) to the two dendronized IONPs. NP10COP@2PG2 disrupted cellular homeostasis (LDH release, IL-1β and IL-8 secretion) to a greater extend than NP10COP@2PG1, which makes this last IONP the best candidate as MRI contrast or theranostic agent. [ABSTRACT FROM AUTHOR]

[Display omitted] • The nanoparticles synthesized using Terminalia catappa leaf extract gave a mixture of Fe 2 O 3 and Fe 3 O 4 nanoparticles. • Cytotoxic behavior of the synthesized nanoparticles showed attack on both the normal (HEK 293) and cervical carcinoma (Hela) cell lines. • The effectiveness of nanoparticles towards anticancer properties depends of reaction conditions. In this research, iron oxide nanoparticles were synthesized by plant-mediated method. Their optical nature, crystallinity, composition, microscopy and sizes were characterized using energy dispersive X-ray, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The microscopic studies revealed spherical/polygonal morphologies with average particle size of 19.14 nm. The in-vitro cytotoxic analysis of the nanoparticles against HEK 293 normal cell lines and Human cervical (Hela) cell lines showed cell toxicity with IC 50 values 44.12 μg and 34.94 μg respectively. The antimicrobial tests showed sensitivity to some micro-organisms whereas some were resistant. In general, the nanoparticles displayed broad spectrum activity with Methicillin Resist Staphaureus (MRSA) showing the greatest growth inhibition. [ABSTRACT FROM AUTHOR]

Understanding water absorbency in paper is challenging as fibre swelling and out-of-plane deformation occur simultaneously during liquid imbibition. Liquid absorption is commonly accessed by gravimetric tests, which provides limited information on the local spatial and temporal distribution of fluid in the substrate. In this work, we developed iron tracers to map liquid imbibition in paper by in situ precipitation of iron oxide nanoparticles during passage of the wetting front. The iron oxide tracers were found to be robustly attached to the cellulosic fibres. After liquid absorption tests, absorbency was investigated by mapping the distribution of iron in 3D using X-ray micro-computed tomography (μCT) and in 2D using energy-dispersive X-ray spectroscopy. We demonstrate a difference in tracer distribution between the wetting front and the fully saturated region supporting that imbibition proceeds in two phases, i.e. liquid percolation through the cell wall initially prior to filling of the external pore spaces. Critically, we demonstrate that these iron tracers enhance image contrast and allow for new imaging modalities in μCT for fibre networks. [Display omitted] [ABSTRACT FROM AUTHOR]

Bionanocomposites fabricated using metal nanoparticles serve a wide range of biomedical applications viz., site targeted drug delivery, imaging etc. Theranostics emerge as an important field of science, which focuses on the use of single entity for both disease diagnosis and treatment. The present work aimed at designing a multifunctional nanocomposite comprising of iron/gold hybrid nanoparticles, coated with oleyl chitosan and conjugated with methotrexate. The HR-TEM images revealed the spherical nature of the composite, while it's nontoxic and biocompatible property was proved by the MTT assay in NIH 3T3 cells and hemolysis assay. Though the VSM results exhibited the magnetic property, the MRI phantom images and X-ray contrast images demonstrated the potential of the composite to be used as contrast agent. Thus the prepared nanocomposite possess good cytocompatibility, magnetic property and also high X-ray attenuation, wherein it could serve as a novel platform for both MRI and CT diagnosis, as well as drug conjugation could aid in targeted drug delivery. [ABSTRACT FROM AUTHOR]

A review of recent developments in the synthesis of hybrid iron oxide–noble metal nanocomposites and their application to various organic reactions is presented herein. Focus is placed on various strategies for achieving (1) Au nanoparticles (NPs) on Fe 3 O 4 @polymer catalysts, (2) optimized dispersion and stability of Fe 3 O 4 /Pd catalysts, (3) Au NPs supported on Fe 2 O 3 –graphene oxide hybrid nanosheets and (4) rose-like Pd–Fe 3 O 4 hybrid nanocomposite-supported Au nanocatalysts. Further application of such hybrid nanocomposites as catalysts for various organic reactions is discussed in brief. [ABSTRACT FROM AUTHOR]

• Size effect of iron oxide NPs (NP10, NP20, NP30, and NP40) was investigated in pumpkin. • TEM and VSM analyses revealed root-to-shoot translocation of all tested NPs. • NP30 exhibits the highest translocation performance, while a negligible amount of NP10 and NP40 reached to the leaves. • The status of nutrient elements significantly altered depend on NP-type. • The findings could be important for selecting the most suitable NP size for agricultural practices. The ability of nanoparticles (NPs) to migrate in the plant body is an important issue to ensure that the NPs reach the desired tissue and to be able to select the most efficient NPs for agricultural applications. In this study, the size impact of four different iron oxide NPs (8–10, 18–20, 20–40, and 30–50 nm referred as NP10, NP20, NP30, and NP40, respectively) on their translocation in pumpkin was elucidated. To assess the root-to-shoot translocation, phloem sap was examined under transmission electron microscope (TEM). In addition, vibrating sample magnetometer (VSM) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses of stem and leaf tissues were performed to confirm size-dependent translocation. TEM and VSM analyses verified root-to-stem translocation of all tested NPs. The NPs treatment significantly altered the abundances of Mn, Cu, K, P, Al, Mg, and Na in tissues. The iron (Fe) content was abundant in plants treated with NP30 and NP20, and the lowest in plants treated with NP10 and NP40. Together with, only NP30 was found to be significantly translocated to the leaves, where it was 393 mg/kg in DW, about 2.3 times that of control. These findings pointed out the size-dependent translocation of NPs. It seems that biological barriers in the vascular bundle appear to restrict the migration, especially for NPs with an average size of 40 nm and above in pumpkins. These findings are important for selecting the most suitable size of iron oxide NPs for use in agricultural practices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and evaluation of a new potential biolubricant from castor oil. • Modified castor seed oil showed potential physiochemical properties using iron oxide as an additive. • ANN based production and optimization was successfully achieved. The study presents the production of biolubricant from castor oil using Fe 3 O 4 nanoparticles and ethylene glycol in a transesterification process, as an additive. Operational parameters such as FAME/alcohol, catalyst loading, and temperature were optimized. The reaction was complete after two hours at 160 °C, giving a yield of 94 %. To enhance the physiochemical properties of modified castor seed oil (MCSO), Fe 3 O 4 nanoparticles and ethylene glycol were used. The biolubricant yield was also predicted using artificial neural networks (ANN). The multilayer perceptron (MLP)-based ANN showed a linear correlation between the output and target values at different temperatures, the amount of catalyst, and the alcohol/FAME ratios during training, testing, and validation. The tribological properties of the biolubricant produced (MCSO + ethylene glycol + 0.5 % Fe 3 O 4 nanoparticles) showed the lowest coefficient of friction (almost 50%) and 40% decreased wear compared to raw castor seed oil and other biolubricant samples produced. [ABSTRACT FROM AUTHOR]

In this research work, a green synthesis approach was utilized to synthesize Sr doped Fe 2 O 3 NPs and Fe 2 O 3 NPs using Egg Albumen with corresponding iron nitrates being precursors. Sr doped Fe 2 O 3 served as a nanophotocatalyst with effective photocatalytic activity and steadiness. The Sr doped Fe 2 O 3 NPs and Fe 2 O 3 NPs photocatalyst was characterized by XRD, FTIR, SEM, EDX, TEM, and UV–visible spectroscopy. Integrating the Sr2+ into the Fe 2 O 3 crystal lattice can significantly broaden the visible region, possibly due to the lowered energy bandgap through the doping energy level created under the conduction band and extended secondary usage wavelength visible light-triggered the photocatalytic efficiency. The synergistic impact between effective sun energy harvesting and charge separation significantly improves photocatalytic activity for TC (Tetracycline) drug degradation under visible light irradiation. The Fe showed high catalytic activity (80%) while Sr/Fe contributed up to 85% in 1 h under visible light, attributed to its narrow range of bandgap energy (∼2.2 eV). The rate constant of Sr/Fe was 1.15 times higher than Fe and hence higher photodegradation. A plausible mechanism of the Sr doped Fe 2 O 3 NPs photocatalytic behavior indicated that surface generated reactive oxygen species, together with strong oxidizing ability, were responsible for the degradation of TC antibiotic drugs into mineral acids like CO 2 , H 2 O some other small molecules. [ABSTRACT FROM AUTHOR]

Abstract: Iron oxide magnetic nano-particles (MNPs) have been prepared in aqueous solution by a modified co-precipitation method. Surface modifications have been carried out using tetraethoxysilane (TEOS), triethoxysilane (TES) and 3-aminopropyltrimethoxysilane (APTMS). The uncoated and coated particle products have been characterized with transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, infrared (IR) and Raman spectroscopy, and thermal gravimetric analysis (TGA). The particle sizes were determined from TEM images and found to have mean diameters of 13, 16 and 14nm for Fe3O4, TES/Fe3O4 and APTMS/Fe3O4, respectively. IR and Raman spectroscopy has been applied to study the effect of thermal annealing on the uncoated and coated particles. The results have shown that magnetite nano-particles are converted to maghemite at 109°C and then to hematite by 500°C. In contrast, the study of the effect of thermal annealing of micro-crystalline magnetite by IR spectroscopy revealed that the conversion to hematite began by 300°C and that no maghemite could be identified as an intermediate phase. IR spectra and TGA measurements revealed that the Si–H and 3-aminopropyl functional groups in TES and APTMS coated magnetite nano-particles decomposed below 500°C while the silica layer around the iron oxide core remained unchanged. The molecular ratio of APTMS coating to iron oxide core was determined to be 1:7 from the TGA data. Raman scattering signals have indicated that MNPs could be converted to maghemite and then to hematite using increasing power of laser irradiation in a manner similar to that observed for thermal annealing. [Copyright &y& Elsevier]

Abstract: Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By utilizing a surface layer of a photoreactive adhesion promoter on the substrates, the MNP–HG films were covalently immobilized during photocrosslinking. The high stability of the composite was documented by rinsing experiments with UV–Vis spectroscopy, while surface plasmon resonance and optical waveguide mode spectroscopy was employed to investigate the swelling behavior in dependence of the nanoparticle concentration, the particle type, and salt concentration. [Copyright &y& Elsevier]

Abstract: A highly efficient process using iron oxide magnetic nanoparticles (IO)-based immunomagnetic separation of tumor cells from fresh whole blood has been developed. The process involved polymer coated 30 nm IO that was modified with antibodies (Ab) against human epithelial growth factor receptor 2 (anti-HER2 or anti-HER2/neu) forming IO-Ab. HER2 is a cell membrane protein that is overexpressed in several types of human cancer cells. Using a HER2/neu overexpressing human breast cancer cell line, SK-BR3, as a model cell, the IO-Ab was used to separate 73.6% (with a maximum capture of 84%) of SK-BR3 cells that were spiked in 1 mL of fresh human whole blood. The IO-Ab preferentially bound to SK-BR3 cells over normal cells found in blood due to the high level of HER2/neu receptor on the cancer cells unlike the normal cell surfaces. The results showed that the nanosized magnetic nanoparticles exhibited an enrichment factor (cancer cells over normal cells) of 1:10,000,000 in a magnetic field (with gradient of 100 T/m) through the binding of IO-Ab on the cell surface that resulted in the preferential capture of the cancer cells. This research holds promise for efficient separation of circulating cancer cells in fresh whole blood. [Copyright &y& Elsevier]

Abstract: Fine powder of iron oxide has been required in the preparation of ferromagnetic α″-Fe16N2 powder in low temperature nitridation. Magnetite and maghemite mixture was obtained by the reaction of iron acetylacetonate Fe(acac)3 in benzyl alcohol. It was reduced to α-Fe in hydrogen at 400°C. Particle size of the α-Fe was 300nm in the reduction of iron oxides obtained from 2g of Fe(acac)3. It decreased to 100nm in the preparation using 8g of Fe(acac)3. After the successive nitridation under ammonia flow at 160°C, the highest yield of α″-Fe16N2 in 66wt.% was observed on the nitrided product from the latter α-Fe, because of the smallest α-Fe particle size after the reduction in the present study. The yield and reproducibility of α″-Fe16N2 formation in low temperature nitridation was improved using the iron oxide prepared in non-aqueous benzyl alcohol compared to the use of magnetite obtained from aqueous solution. [Copyright &y& Elsevier]

Abstract: Crystallization and magnetic property of Fe2O3 nanoparticle precipitated in SiO2 matrix was investigated. Fe2O3/SiO2 nanocomposite thin film was obtained by annealing of the amorphous Fe–Si–O thin film deposited by RF-magnetron sputtering of (α-Fe2O3)1−x /(SiO2) x composite targets. The Fe2O3 crystallite size increased with decreasing SiO2 area ratio, x of the target and increasing annealing temperature. ɛ-Fe2O3 with the crystallite size of 20–30nm was obtained after annealing the film deposited in SiO2 area ratio, x =0.33–0.42 at 900°C. Lower SiO2 area ratio (x) than 0.25 and higher annealing temperature resulted in precipitation of α-Fe2O3 with the larger crystallite size than 40nm. In the case of SiO2 area ratio, x ≥0.50, the annealed film was amorphous and showed higher magnetization and smaller coercivity due to the precipitation of very small crystalline γ-Fe2O3. The ɛ-Fe2O3/SiO2 composite thin film showed ferromagnetic hysteresis with coercive force of 0.14T. [Copyright &y& Elsevier]

Abstract: A fabrication method of Cy5.5-MMP substrate and PEG conjugated iron oxide nanoparticles with thin silica coating (PCM-CS) and its potential as an ‘activatable’ dual imaging probe for tumor imaging is described in this report. PCM-CS showed an intensity-averaged diameter of 43.1±6.3nm by dynamic light scattering without any noticeable aggregation over 7days. Fluorescence of Cy5.5 on the surface of nanoparticles was fully quenched and the quenching efficiency was 97.2%. PCM-CS showed protease specific fluorescence recovery in vitro caused from the specific peptide cleavage by MMP-2 and the probe displayed the sensitivity on 0.5nM or less enzyme concentration. Tumor was successfully visualized by NIRF and MRI in vivo by intravenously injected PCM-CS. NIRF signal of tumor was gradually increased up to 12h post injection and the intensity of tumor was about 3–4 times higher than normal tissue. NIRF signal at MMP-2 inhibitor treated tumor was clearly lower than tumor without inhibitor due to the insufficient peptide cleavage. NIRF signal at excised tumor was 5–10 times stronger than other organs. Noticeable darkening in magnetic resonance image was observed at the tumor region and the image was gradually darkened at 12h post injection of PCM-CS. The maximum signal difference between tumor region and healthy muscle was 34%. [Copyright &y& Elsevier]

Summary: The safe use of inorganic nanoparticles (NPs) in biomedical applications remains an unresolved issue. The present review presents an overview of the cytotoxic effects of commonly used inorganic NPs: quantum dots, gold and iron oxide nanoparticles. The main focus is on presenting recent findings and identifying similar cytotoxic effects which appear common to all these NPs. Next, several considerations are provided for optimizing cell–NP interaction studies which could aid in improving our understanding of NP toxicity. Finally, several critical NP parameters are discussed and suggestions are made on how to optimize NP design in view of minimal cytotoxicity. [ABSTRACT FROM AUTHOR]

Abstract: A new electrode structure based on a three-dimensional mesoporous matrix was developed. Nanoparticles of γ-iron oxide (Fe2O3) were introduced into the mesopores of a carbon matrix (mesoporous carbon, CMK-3) by oxidizing metallic iron, which was electroplated in the matrix. The resulting structure was found to have a high charge–discharge capacity when used as the positive electrode of a lithium battery. The iron oxide nanoparticles bonded tightly to the electrically conductive electrode framework, and showed a high activity for the electrochemical reaction: Fe2O3 +6Li→3Li2O+2Fe. [Copyright &y& Elsevier]

Abstract: Surface silvered polyimide (PI)/Fe2O3 composite films with both superparamagnetic and surface electrically conductive properties have been fabricated by an in situ technique. Iron (III) 2,4-pentanedionate was incorporated into a PI precursor poly(amic acid) solution and thermally decomposed to form iron oxide nanoparticles in the process of thermal imidization, preparing PI/Fe2O3 nanocomposite films. The establishment of a silver layer on the PI/Fe2O3 film surface involved the steps of chemical etching by the alkaline aqueous solution, ion exchange with silver ions and chemical reduction by glucose. The formed Fe2O3 particles of the nano scale endow the film with typical superparamagnetic response. By employing the etching time of only 10min and a reduction time of no more than 15min, the well-established silver layers have formed on the upside surface. The corresponding reflectivity and resistivity reached to the value of 76.15% and 0.7Ω/square respectively. [ABSTRACT FROM AUTHOR]

Abstract: We developed electrochemical biosensors based on enzyme functionalized nanoparticles of different compositions for the detection of bisphenol A. We utilized for the first time magnetic nickel nanoparticles as an enzyme immobilization platform and electrode material to construct screen-printing enzyme biosensors for bisphenol A. We compared the analytical performance of these sensors with those based on iron oxide (Fe3O4) and gold nanoparticles. The proposed biosensor format exhibited fast and sensitive amperometric responses to bisphenol A with a response time of less then 30s. Among the three configurations, nickel provided comparable or better characteristics in terms of detection limit and sensitivity than Fe3O4 and gold nanoparticles. The biosensors were characterized by good reproducibility, stability of more than 100 assays (residual activity for nickel was 98%) and a wide linear range which spanned from 9.1×10−7 to 4.8×10−5 M for nickel, 2.2×10−8 to 4.0×10−5 M for Fe3O4 and 4.2×10−8 to 3.6×10−5 M for gold. The highest sensitivity was obtained with nickel. The detection limits for the three types of biosensors were: 7.1×10−9, 8.3×10−9 and 1×10−8 M for nickel, Fe3O4 and gold nanoparticles in that order, respectively. These results demonstrate that nickel nanoparticles can be successfully used in the construction of electrochemical enzyme sensors for the detection of phenolic compounds. [Copyright &y& Elsevier]

Abstract: Spincoating colloidal solutions of monodisperse nanoparticles onto flat silica supports offers a facile and flexible way to produce model catalysts with well defined catalyst loading and particle size. By spincoating iron oxide (magnetite) nanoparticles with varying particle diameter we produce a model system for iron based Fischer–Tropsch catalysts. In this proof of principle study we employ a combination of surface spectroscopy (XPS) and transmission electron microscopy (TEM) to investigate the changes in surface chemistry and morphology of the model catalysts upon catalyst pretreatment and exposure to syngas. [Copyright &y& Elsevier]

Abstract: With the goal to achieve highly efficacious MRI-monitored magnetic targeting, a novel drug carrier with dual nature of superior magnetophoretic mobility and superparamagnetism was synthesized. This carrier was specially designed in a core-shell structure. The core was achieved by utilizing a strategy of self-assembly of oppositely charged ultrafine superparamagnetic iron oxide nanoparticles previously prepared. The final particles were formed by coating such cores with carboxymethyldextran (CMD) polymer. By exclusion of non-magnetic materials from the interior part of the particles, this structure maximized the amount of magnetic material and thus yielded a superior magnetophoretic mobility. Such a strategy avoids the challenge of superparamagnetism loss, which would be caused by cores exceeding a critical domain size. Coating the self-assembled core enables the magnetic carrier to be stable upon usage and storage and to be readily linked with drug molecules for therapeutic applications. In vitro characterization showed that these nanoparticles displayed a 3- to 4-fold enhancement in magnetophoretic mobility, and a markedly improved stability when stored in 50% serum as a comparison of conventional iron oxide-based magnetic nanoparticles. Preliminary in vivo studies revealed that the nanoparticles also function well as a contrast enhancer for MR imaging of brain glioma. This technology could lead to the development of a new paradigm of magnetic carriers that meet with the needs of various clinical applications. [Copyright &y& Elsevier]

Abstract: Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane. [Copyright &y& Elsevier]

Abstract: Previously we reported that plasma kallikrein and high molecular weight kininogen attach to the surface of dextran-coated superparamagnetic iron oxide nanoparticles (SPION) through the incompletely covered iron oxide core (Simberg et al., Biomaterials, 2009). Here we show that SPION also activate kallikrein–kinin system in vitro and in vivo. The serine protease activity of kallikrein was stably associated with SPION and could be detected on the nanoparticles even after extensive washing steps. The enzymatic activity was not detectable in kininogen-deficient and Factor XII-deficient plasma. The enzymatic activation could be blocked by precoating SPION with histidine-rich Domain 5 (D5) of kininogen. Importantly, the kallikrein activity was detectable in plasma of SPION-injected, but not of D5/SPION-injected mice. Tumor-targeted SPION when injected into kininogen-deficient and control mice, produced high levels of vascular clotting in tumors, suggesting that kallikrein activation is not responsible for the nanoparticle-induced thrombosis. These data could help in understanding the toxicity of nanomaterials and could be used in designing nanoparticles with controlled enzymatic activity. [Copyright &y& Elsevier]

Abstract: The aim of this study was to develop a novel polymeric magnetic nanoprobe as an MRI contrast agent to target hepatocytes, as well as to evaluate the targeting ability of the nanoprobe with MRI in vivo. Superparamagnetic iron oxide nanocrystals (SPIONs) were synthesized by a thermal decomposition and seed growth method. An 1-ethyl-3-(3-(dimethylamino)-propyl) carbodiimide (EDC)-mediated reaction coupled water-soluble chitosan (WSC) to linoleic acid (LA). Twelve-nanometer-sized SPIONs were incorporated into the core of self-assembled WSC–LA nanoparticles. The morphology and size distribution of the SPION-loaded WSC–LA nanoparticles (SCLNs) were determined by transmittance electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The encapsulation of SPIONs in the WSC–LA nanoparticles reduced the cytotoxicity of bare iron particles and enhanced their dispersion ability in water. The clustering of SPIONs into WSC–LA nanoparticles showed ultrasensitive magnetic behavior. After in vivo intravascular SCLN injection, MRI revealed relative signal enhancement in the liver. The localization of SCLN in hepatocytes was confirmed by Prussian blue staining and TEM analysis. We have successfully developed an ultrasensitive SCLN that effectively targets hepatocytes. The SCLN can be used as a contrast agent to aid in the diagnosis of hepatic diseases. [Copyright &y& Elsevier]

Abstract: Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles’ easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size. [Copyright &y& Elsevier]

Abstract: Fe3O4–poly(3,4-ethylene-dioxythiophene) (PEDOT) core-shell nanoparticles as heterogeneous Fenton catalysts were synthesized by acid etching-mediated chemical oxidation polymerization. Compared with pristine Fe3O4 nanoparticles or commercialized iron oxide nanopowder, Fe3O4–PEDOT core-shell nanoparticles demonstrated outstanding catalytic performance for the degradation of Reactive Black 5 (RB5) and Orange II. In the case of the degradation of RB5, Fe3O4–PEDOT core-shell nanoparticles had an approximately 2.5 times higher catalytic activity than commercialized Fe3O4 nanopowder. In addition, the ultrathin PEDOT shell can suppress leaching of iron cation through coordination formation, facilitating the catalytic reaction in the confined region of the nanoparticle surface. [Copyright &y& Elsevier]

Abstract: The influence of the composition of the polymer coated polyvinyl alcohol (PVA), vinyl alcohol/vinyl amine copolymer (A-PVA) and polyethylenimine (PEI) coated superparamagnetic iron oxide nanoparticles (SPIONs) on the colloidal stability, cytotoxicity and cellular uptake of these particles in different cell media is reported in this paper. Although all examined polymer coated SPIONs were stable in water and PBS buffer these colloidal systems had different stabilities in DMEM or RPMI media without and supplemented with fetal calf serum (FCS). We found that A-PVA coating onto the surface of the SPIONs decreased the cytotoxicity of the polymer compared to the same concentration of A-PVA alone. As well, polyplexes of PEI-SPIONs with DNA in concentration used for transfection experiments showed no cytotoxicity compared to PEI and PEI-SPIONs. Our data show that the choice of medium largely influences the uptake of these particles by HeLa cells. The optimal medium is different for the different examined polymer coated SPIONs and it should be determined in each case, individually. [Copyright &y& Elsevier]

Abstract: The electrochemical reaction mechanisms of tridymite FePO4 with Li ions were studied in the voltage range of 2.4–0V. The lithiation/delithiation of FePO4 was found to be similar to that of binary 3d-metal oxides, which involve the formation and decomposition of Li2O along with the reduction and oxidation of nanoscale 3d-metal nanoparticles. In the first discharge, FePO4 was reduced to metallic Fe nanoparticles dispersed in a lithium compound matrix consisting of Li3PO4 and Li2O. In the subsequent charge, these metallic Fe nanoparticles were partially oxidized to FeO by the decomposition of Li2O. The Li3PO4 matrix was inactive during the change of potential from 0 to 2.4V. It is notable that the re-oxidation of metallic Fe occurred only in the case of small nanoparticles, and the large Fe particles remained electrochemically inert during the reversible reaction. [Copyright &y& Elsevier]

Abstract: Synthesis of magnetite (Fe3O4) nanoparticles under oxidizing environment by precipitation from aqueous media is not straightforward because Fe2+ gets oxidized to Fe3+ and thus the ratio of Fe3+:Fe2+=2:1 is not maintained during the precipitation. A molar ratio of Fe3+:Fe2+ smaller than 2:1 has been used by many to compensate for the oxidation of Fe2+ during the preparation. In this work, we have prepared iron oxide nanoparticles in air environment by the precipitation technique using initial molar ratios Fe3+:Fe2+⩽2:1. The phases of the resulting powders have been determined by several techniques. It is found that the particles consist mainly of maghemite with little or no magnetite phase. The particles have been suspended in non-aqueous and aqueous media by coating the particles with a single layer and a bilayer of oleic acid, respectively. The particle sizes, morphology and the magnetic properties of the particles and the ferrofulids prepared from these particles are reported. The average particle sizes obtained from the TEM micrographs are 14, 10 and 9nm for the water, kerosene and dodecane-based ferrofluids, respectively, indicating a better dispersion in the non-aqueous media. The specific saturation magnetization (σs) value of the oleic-acid-coated particles (∼53emu/g) is found to be lower than that for the uncoated particles (∼63emu/g). Magnetization σs of the dodecane-based ferrofluid is found to be 10.1emu/g for a volume fraction of particles ϕ=0.019. Zero coercivity and zero remanance on the magnetization curves indicate that the particles are superparamagnetic (SPM) in nature. [Copyright &y& Elsevier]

Abstract: We describe in this paper an approach to synthesize superparamagnetic iron oxide nanoparticles in the presence of polymerized lactic acid. The resulted particles consisted of clusters of iron oxide monocrystals, embedded inside the polymer chains. The composite particles synthesized in situ were highly dispersible in aqueous solution with good stability. X-ray diffraction and magnetometer data all confirmed the crystalline structure and super-paramagnetic property of the particles. They exhibited narrow size distribution with hydrodynamic diameters close to 80nm. In addition, the particles were shown to have abundant surface carboxyl groups, which can be used to conjugate various biomolecules. Such a preparation would be especially useful for developing target specific MRI contrast agents or drug delivery vehicles. [Copyright &y& Elsevier]

Abstract: Nanostructured pure and silica-supported iron oxide materials have been prepared by the aerogel approach. Pure iron oxide powder derived from sol-gel ferric acetylacetonate formed agglomerates of 5–30nm small crystallites of hematite and maghemite according to TEM identification of crystal faces. Depositing ferric species to mesoporous silica aerogels generated 1–5nm particles in the amorphous matrix. They were evaluated for methanol oxidation in an ambient fixed-bed flow reactor from 225 to 300°C. Product selectivity and oxidation activity were dependent upon iron dispersion and reactor operation. The formation of dimethyl ether was mainly related to the bulk phase and Lewis acidity of iron oxide. Active catalysts that were selective to formaldehyde and methyl formate required appropriate iron dispersion on the silica surface, including a strong electronic interaction. Methoxy transformation to formaldehyde and formate species was found to be a function of surface temperature based on a Fourier transform infrared (FT-IR) analysis. Low to moderate reactor temperature and short catalyst contact time favored methanol conversion to formaldehyde. The formation of methyl formate was found to compete with that of formaldehyde. The dependence of response time on oxygen feed attenuation suggests that mobile lattice oxide ions participate in the surface reaction and that oxygen molecules help to maintain surface iron sites highly oxidized for Lewis chemisorption and redox electron transfer. A good correlation between microstructures and reaction characteristics is proposed. [Copyright &y& Elsevier]

Abstract: The detection of superparamagnetic iron oxide nanoparticles (SPION) in synoviocytes is reported. Synoviocytes were incubated for 2, 12, 24 and 48h with 1.5mg/ml of PVA coated SPION under the influence of magnets (12h). Particles were well tolerated by the synoviocytes, were easily detected using the Turnbulls and Prussian blue reactions between 12 and 24h. [Copyright &y& Elsevier]

Abstract: Magnetic nanocarrier consisting of iron oxide and gold was synthesized in an aqueous solution by using -ray irradiation. UV–vis absorption spectra showed surface plasmon resonance of nano-sized metallic gold. The surface of quasicore–shell structured magnetic iron oxide nanocarriers was almost covered with gold grains after having the gold grains grow over the iron oxides. [Copyright &y& Elsevier]

Abstract: Novel superparamagnetic iron oxide nanoparticles coated with polymerized PEGylated bilayers were prepared. Bilayers composed of 10-undecenoic acid (UD) inner and UDPEG (PEG ester of UD) outer layers are resistant to aggregation after -irradiation. Various methods of coating were developed to prepare small (60–100nm) and ultrasmall (20–35nm) particles without size separation processes. [Copyright &y& Elsevier]

Nanoparticle iron oxide catalyst was studied to determine the phase changes that occur during catalysis experiments and to determine if these changes could explain the oxidative catalysis and deactivation mechanisms. The starting material was characterized as a mixture of glassy material, poorly crystalline iron hydroxides, and a small amount of highly crystalline γ-Fe2O3. Under oxidative (with respect to phase changes in iron oxide) heating conditions (3% oxygen and higher) this material transformed to a much coarser α-Fe2O3, γ-Fe2O3, or Fe3O4 phase depending on the conditions of the experiment. When the material was pre-heated to intentionally transform it to α-Fe2O3, and then later exposed to catechol vapors below 450 °C, the α-Fe2O3 was further transformed to either an oxygen deficient γ-phase or to magnetite even though input oxygen tension remained well above the magnetite (Fe3O4), hematite (α-Fe2O3) phase boundary. These two phases (γ-Fe2O3 and magnetite), both of which are spinels, do not seem to be catalytically active for either the oxidation of CO or the oxidative degradation of catechol. It is proposed that the appearance of these phases are evidence of an intermediate reduction step in the oxidative catalysis mechanism performed by iron oxide. Specifically, this provides ex situ analytical evidence that a mechanism similar to the Mars–van-Krevelan mechanism operated for the catalysis by bulk crystalline iron oxide. Subsequent oxidation of the reduced iron oxide would normally regenerate the α-phase completing the Mars–van-Krevelan cycle. However, in cases where the rate of reduction exceeds the rate of oxidation, the iron oxide permanently transforms to a spinel and catalysis halts even though one of these spinels, maghemite (γ-Fe2O3), has no stability field in P–T space with respect to magnetite and hematite. The appearance of magnetite is similar to the results expected for reducing conditions and further attests to the role of α-Fe2O3 as an oxygen source during catalysis rather than as an electron acceptor. [Copyright &y& Elsevier]

NANOCAT® Superfine Fe2O3 nanoparticles were evaluated both as a catalyst and as an oxidant for carbon monoxide oxidation. It was found that the nanoparticles are much more effective as carbon monoxide catalysts than the non-nano oxide powder. For the Fe2O3 nanoparticles, the reaction order is first-order with respect to the partial pressure of carbon monoxide, and zero-order with respect to the partial pressure of oxygen. The apparent activation energy was 14.5 kcal mol−1 and the normalized reaction rate was 19 s−1 m−2 at 300 °C. In the absence of oxygen, Fe2O3 nanoparticles oxidize carbon monoxide directly as an oxidant. The resulting reduced forms of Fe2O3 also catalyze a disproportionation reaction for a considerable amount of carbon monoxide. The significant amount of carbon monoxide it can remove through the catalytic oxidation, direct oxidation, and the disproportionation reaction make it a very promising material in certain special applications, such as removing the carbon monoxide from a burning cigarette, where the potential toxicity of other, more conventional catalysts would be undesirable. The higher activity of Fe2O3 nanoparticles over non-nano Fe2O3 powders was attributed to a small particle size (3 nm), the presence of an hydroxylated phase of iron oxide (FeOOH), as revealed by both high resolution transmission electron microscopy (HRTEM) and a comparable study of FeOOH (goethite) powder. [Copyright &y& Elsevier]

α-Fe2O3 nanoparticles with controlled dispersion were obtained by using a mixed type of mechanical and ultrasonic milling with the addition of surfactant, in which particle refinement was done mechanically, and dispersion was done physically and chemically. The particle refinement and dispersion degree of the α-Fe2O3 were examined by TEM observation and analyses of turbidity as well as FT-IR spectra of the particle-dispersed solution. Smaller particle size and addition of 1% n-octyl alcohol surfactant make the dispersion effect better. This improved dispersion of the nanoparticles was attributable to increased adsorption of hydroxide ions on α-Fe2O3 nanoparticle surfaces as its area increased. [Copyright &y& Elsevier]

Magnetic and magnetotransport measurements were performed on gas-phase synthesized Fe nanoparticles subjected to surface oxidation and cold consolidation. Two samples were investigated with α-Fe volume fraction of 0.15 and 0.60. The sample with smaller metallic fraction is below the percolation threshold for metallic conduction and the conduction mechanism is dominated by thermally activated processes across the oxide. In this case, by lowering the temperature, an increase of the negative magnetoresistance is observed up to 5% at 50 K in a magnetic field of 70 kOe. The magnetoresistance dependence on the sample magnetization, temperature and sample composition is discussed considering the magnetic correlations present in these nanostrucuterd systems. [Copyright &y& Elsevier]

Iron oxide (Fe 2 O 3) is an intriguing anode material of electrochemical energy storage systems such as rechargeable batteries. The rational design of its nanostructure at mild condition to cope with the issues of low reversible capacity and sluggish kinetics is required. Herein, an efficient, facile, and potentially large-scale synthesis approach using the precursor of laminated iron oxychloride@polyaniline heterostructure and mild annealing is developed, yielding unique Fe 2 O 3 @carbon nanocomposites with hematite nanoparticles (∼20 nm) that embedded in nitrogen/chlorine-doped carbon nanodisk (N/Cl–C). Given the benefit of abundant active sites, good chemical contact between carbon and Fe 2 O 3 , and robust composite structure, the as-prepared Fe 2 O 3 @N/Cl–C anode material delivers competent lithium-ion storage properties, including high reversible capacity of 1010 mAh g−1 (based on the mass of the as-prepared nanocomposite) at 0.1 A g−1, decent rate performance upon a rigorous current change, and superior cycling stability with 955 mAh g−1 after 180 cycles as well as a sustained Coulombic efficiency of about 99%. This structural design may provide a new avenue for achieving efficient iron oxide-based materials in chemical and electrochemical applications such as catalysis, lithium-ion batteries, and sodium-ion batteries. Image 1 • Developing a novel, facile and scalable synthesis approach for hematite/carbon nanocomposites. • N/Cl-doped carbon nanodisk-encapsulated hematite anode shows robust structure for Li-ion storage. • High reversible capacity, decent rate capability and superior cycling performance are achieved. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles with a superparamagnetic iron oxide core were prepared in this work, in order to obtain multifunctional platforms with adequate features for cancer theranostics. Three different core-shell nanocomplexes were obtained: IO-OAm/mSiO 2 , IO-APTES/mSiO 2 and IO/SiO 2 /mSiO 2. In the case of IO-OAm/mSiO 2 and IO-APTES/mSiO 2 , iron oxide (IO) was obtained by thermal decomposition, having in this case a coating of oleylamine (OAm) that was in the second formulation exchanged by (3-aminopropyl)triethoxysilane ligand (APTES). Regarding the IO/SiO 2 /mSiO 2 formulation, iron oxide was synthesized by microemulsion. The mesoporous silica shell (mSiO 2) on the IO nanoparticles was obtained by sol-gel and the final materials were dried by supercritical fluids drying. VSM confirmed the superparamagnetic behaviour of the nanoparticles, leading to M S of 4.0, 1.8 and 10.2 emu·g−1, for IO-OAm/mSiO 2 , IO-APTES/mSiO 2 and IO/SiO 2 /mSiO 2 , respectively. NMR relaxometry has shown the potential of these nanoparticles to be used as T 2 contrast agents, with r 2 values as high as 63.93 s−1·mM−1 Fe. The three types of nanoparticles exhibited loading contents of epirubicin of ~3% and drug release percentages of 19% for IO-OAm/mSiO 2 , 24% for IO-APTES/mSiO 2 and 31% for IO/SiO 2 /mSiO 2. The cytotoxicity of drug-loaded and non-loaded most promising nanoparticles was assessed, showing high potential of these platforms for application as anticancer drug carriers. Unlabelled Image • Superparamagnetic iron oxide/mesoporous SiO 2 core-shell nanoparticles are prepared. • New ligand exchange and supercritical fluids drying approaches were applied. • Higher % of released epirubicin compared to the literature: up to 30% after 48 h • Potential as T 2 contrast agents for MRI, with r 2 as high as 63.93 s−1·mM−1 Fe. • Promising biocompatible multifunctional platforms for cancer theranostics [ABSTRACT FROM AUTHOR]

Abstract: The present work is a modification for Serpen et al.’s method for antioxidant activity determination for insoluble materials with special reference to metal oxide nanoparticles. As reported in our former publications the mixing procedures were followed as mentioned by Serpen et al. A new mixing procedure was followed for enhancing the reaction between metal oxide nanoparticles and DPPH in the solution. The sonication inside a water bath enhances the DPPH scavenging capacity of metal oxide nanoparticles up to 13.94% and 18.96% in case of ferric oxide and nickel oxide nanoparticles respectively. The control DPPH solution without any nanoparticles does not show any degradation due to sonication. [Copyright &y& Elsevier]

Abstract: We have synthesized the iron oxide nanoparticles using the newly developed mechanical ultrasonication method with the FeSO4 ·7H2O. We have also investigated the crystallographic structural properties, morphology, and magnetic properties of the nanopowders. According to the high resolution X-ray diffraction result, the as-synthesized iron oxide nanoparticles were magnetite (Fe3O4). The particle size of the magnetite nanoparticles was about 6nm confirmed by transmission electron microscopy image. The particle shape was almost a sphere confirmed by scanning electron microscopy image. The coercivity and saturation magnetization of the as-synthesized iron oxide nanopowders were 114Oe, and 3.7emu/g, respectively. [Copyright &y& Elsevier]

• Photothermal boiling of an aqueous suspension of iron oxide was studied. • The addition of particles increases the evaporation efficiency of water. • Evaporation efficiency increased by at least 12% at 3 wt% particle concentration. • The model predicting steam flowrate and optimal particle concentration was developed. • The process was established in-situ using a solar concentrator. Photo-thermal evaporation of nanofluids has potential applications in solar desalination, micro-CHP (combined heat and power) and domestic off-grid disinfection. In this research, we reproduced the process experimentally using 110-nm iron oxide particles dispersed in water. At an initial lab-scale stage, under the artificial radiation of 6.9 suns, we observed that the boiling nanofluid destabilizes to a suspension of 6µm agglomerates of nanoparticles and that up to 30% of the particles escape the system with the steam. At the prototype stage, we boiled the fluid in a solar concentrator producing 35 g/min steam with an efficiency of around 60%, which is sufficient to drive a small turbine. The optimum concentration of the nanoparticles was 3 wt%. To supplement the experiments, we developed a simplified model for engineering calculations of the solar steam generation rate. The model corresponds well to the experiments deviating by only 8%. [ABSTRACT FROM AUTHOR]

• Industrial-scale preparation of low-cost magnetite nanoparticles. • Transfer of laboratory synthesis to a continuous-flow process. • Method based on oxidative precipitation of Fe2+ controlled by OH− excess. • Nanoparticles' dimensions range from 40 to 300 nm. • Improved magnetic hyperthermia efficiency validated for developed nanoparticles. Continuous processes are always preferred over batch ones when reproducible and scalable industrial procedures are needed. This work illustrates the production of magnetite nanoparticles by oxidative precipitation in aqueous media, following a continuous approach that offers additional advantages. Particularly, the developed reaction setup succeeds (i) the complete separation of the green rust's precipitation from Fe 3 O 4 nucleation, (ii) the achievement of constant concentrations in all ionic and solid forms throughout the production line when steady-state is reached, what means constant supersaturation from both the formation of green rust and Fe 3 O 4 , and (iii) the possibility to control critical parameters, such as OH− excess over the initial stoichiometric Fe(OH) 2 precipitation, through on-line regulation of synthesis parameters such as the reactor's pH and redox potential. Importantly, continuous flow synthesis of Fe 3 O 4 nanoparticles enables high production capacities, low energy consumption and proportional scale-up at any volume. As a proof of concept, obtained nanoparticles were evaluated according to their magnetic response as potential magnetic hyperthermia agents indicating significant improvement of heating efficiency that goes up to 1.5–2 kW/g Fe3O4 for both smaller (~40 nm) and larger (~200 nm) particles. [ABSTRACT FROM AUTHOR]

Ultrasonic humidifier use is a potential source of human exposure to inhalable particulates. This research evaluated the behavior of insoluble iron oxide and aluminum oxide particles in water used to fill room-sized ultrasonic humidifiers. Solutions of 10 mg/L Fe, as iron oxide particles, or 5 mg/L Al, as aluminum oxide suspension, were added into tap water used to fill ultrasonic humidifiers. The humidifiers were operated for 14 h; samples were obtained over time and monitored for soluble and particulate Fe and Al, as well as particle sizes in the humidifier reservoir and emitted in aerosols. Denser, settleable particles of approximately 1.5 μm diameter of iron or aluminum oxides accumulated at the bottom of the humidifier reservoir. Smaller, suspended metal oxide particles of 0.22–0.57 μm diameter were emitted as aerosols from the humidifier. Soluble anions and cations in tap water were also present in the aerosols emitted from humidifiers. The results indicate that a typical 1.6 MHz ultrasonic humidifier can emit 0.22–0.57 μm particles and dissolved minerals from fill water into breathable air. Image 1 • Room-sized ultrasonic humidifiers potentially expose human to inhalable particles. • Room-sized ultrasonic humidifiers emit 0.22–0.57 μm metal oxide particles. • Denser than water particles were emitted at a low percent due to gravity settling. • Suspended particles larger than 0.22–0.57 μm are poorly emitted. [ABSTRACT FROM AUTHOR]