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17 pages, 4914 KiB

Open AccessArticle

Energetic Electron-Assisted Synthesis of Tailored Magnetite (Fe₃O₄) and Maghemite (γ−Fe₂O₃) Nanoparticles: Structure and Magnetic Properties

by Johannes Dietrich, Alexius Enke, Nils Wilharm, Robert Konieczny, Andriy Lotnyk, André Anders and Stefan G. Mayr

Nanomaterials 2023, 13(5), 786; https://doi.org/10.3390/nano13050786 - 21 Feb 2023

Cited by 6 | Viewed by 2539

Abstract

Iron oxide nanoparticles with a mean size of approximately 5 nm were synthesized by irradiating micro-emulsions containing iron salts with energetic electrons. The properties of the nanoparticles were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, selective area diffraction and vibrating sample [...] Read more.

Iron oxide nanoparticles with a mean size of approximately 5 nm were synthesized by irradiating micro-emulsions containing iron salts with energetic electrons. The properties of the nanoparticles were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, selective area diffraction and vibrating sample magnetometry. It was found that formation of superparamagnetic nanoparticles begins at a dose of 50 kGy, though these particles show low crystallinity, and a higher portion is amorphous. With increasing doses, an increasing crystallinity and yield could be observed, which is reflected in an increasing saturation magnetization. The blocking temperature and effective anisotropy constant were determined via zero-field cooling and field cooling measurements. The particles tend to form clusters with a size of 34 nm to 73 nm. Magnetite/maghemite nanoparticles could be identified via selective area electron diffraction patterns. Additionally, goethite nanowires could be observed. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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22 pages, 6318 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Phosphate Capture Enhancement Using Designed Iron Oxide-Based Nanostructures

by Paula Duenas Ramirez, Chaedong Lee, Rebecca Fedderwitz, Antonia R. Clavijo, Débora P. P. Barbosa, Maxime Julliot, Joana Vaz-Ramos, Dominique Begin, Stéphane Le Calvé, Ariane Zaloszyc, Philippe Choquet, Maria A. G. Soler, Damien Mertz, Peter Kofinas, Yuanzhe Piao and Sylvie Begin-Colin

Nanomaterials 2023, 13(3), 587; https://doi.org/10.3390/nano13030587 - 1 Feb 2023

Cited by 6 | Viewed by 2526

Abstract

Phosphates in high concentrations are harmful pollutants for the environment, and new and cheap solutions are currently needed for phosphate removal from polluted liquid media. Iron oxide nanoparticles show a promising capacity for removing phosphates from polluted media and can be easily separated [...] Read more.

Phosphates in high concentrations are harmful pollutants for the environment, and new and cheap solutions are currently needed for phosphate removal from polluted liquid media. Iron oxide nanoparticles show a promising capacity for removing phosphates from polluted media and can be easily separated from polluted media under an external magnetic field. However, they have to display a high surface area allowing high removal pollutant capacity while preserving their magnetic properties. In that context, the reproducible synthesis of magnetic iron oxide raspberry-shaped nanostructures (RSNs) by a modified polyol solvothermal method has been optimized, and the conditions to dope the latter with cobalt, zinc, and aluminum to improve the phosphate adsorption have been determined. These RSNs consist of oriented aggregates of iron oxide nanocrystals, providing a very high saturation magnetization and a superparamagnetic behavior that favor colloidal stability. Finally, the adsorption of phosphates as a function of pH, time, and phosphate concentration has been studied. The undoped and especially aluminum-doped RSNs were demonstrated to be very effective phosphate adsorbents, and they can be extracted from the media by applying a magnet. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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25 pages, 5798 KiB

Open AccessArticle

Investigation of Aggregation and Disaggregation of Self-Assembling Nano-Sized Clusters Consisting of Individual Iron Oxide Nanoparticles upon Interaction with HEWL Protein Molecules

by Ruslan M. Sarimov, Egor I. Nagaev, Tatiana A. Matveyeva, Vladimir N. Binhi, Dmitriy E. Burmistrov, Dmitriy A. Serov, Maxim E. Astashev, Alexander V. Simakin, Oleg V. Uvarov, Venera V. Khabatova, Arthur G. Akopdzhanov, Nicolai L. Schimanowskii and Sergey V. Gudkov

Nanomaterials 2022, 12(22), 3960; https://doi.org/10.3390/nano12223960 - 10 Nov 2022

Cited by 14 | Viewed by 2406

Abstract

In this paper, iron oxide nanoparticles coated with trisodium citrate were obtained. Nanoparticles self-assembling stable clusters were ~10 and 50–80 nm in size, consisting of NPs 3 nm in size. The stability was controlled by using multi-angle dynamic light scattering and the zeta [...] Read more.

In this paper, iron oxide nanoparticles coated with trisodium citrate were obtained. Nanoparticles self-assembling stable clusters were ~10 and 50–80 nm in size, consisting of NPs 3 nm in size. The stability was controlled by using multi-angle dynamic light scattering and the zeta potential, which was −32 ± 2 mV. Clusters from TSC-IONPs can be destroyed when interacting with a hen egg-white lysozyme. After the destruction of the nanoparticles and proteins, aggregates are formed quickly, within 5–10 min. Their sizes depend on the concentration of the lysozyme and nanoparticles and can reach micron sizes. It is shown that individual protein molecules can be isolated from the formed aggregates under shaking. Such aggregation was observed by several methods: multi-angle dynamic light scattering, optical absorption, fluorescence spectroscopy, TEM, and optical microscopy. It is important to note that the concentrations of NPs at which the protein aggregation took place were also toxic to cells. There was a sharp decrease in the survival of mouse fibroblasts (Fe concentration ~75–100 μM), while the ratio of apoptotic to all dead cells increased. Additionally, at low concentrations of NPs, an increase in cell size was observed. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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20 pages, 5043 KiB

Open AccessArticle

Fe₃O₄-PEI Nanocomposites for Magnetic Harvesting of Chlorella vulgaris, Chlorella ellipsoidea, Microcystis aeruginosa, and Auxenochlorella protothecoides

by Kristína Gerulová, Alexandra Kucmanová, Zuzana Sanny, Zuzana Garaiová, Eugen Seiler, Mária Čaplovičová, Ľubomír Čaplovič and Marián Palcut

Nanomaterials 2022, 12(11), 1786; https://doi.org/10.3390/nano12111786 - 24 May 2022

Cited by 19 | Viewed by 3196

Abstract

Magnetic separation of microalgae using magnetite is a promising harvesting method as it is fast, reliable, low cost, energy-efficient, and environmentally friendly. In the present work, magnetic harvesting of three green algae (Chlorella vulgaris, Chlorella ellipsoidea, and Auxenochlorella protothecoides) and one [...] Read more.

Magnetic separation of microalgae using magnetite is a promising harvesting method as it is fast, reliable, low cost, energy-efficient, and environmentally friendly. In the present work, magnetic harvesting of three green algae (Chlorella vulgaris, Chlorella ellipsoidea, and Auxenochlorella protothecoides) and one cyanobacteria (Microcystis aeruginosa) has been studied. The biomass was flushed with clean air using a 0.22 μm filter and fed CO₂ for accelerated growth and faster reach of the exponential growth phase. The microalgae were harvested with magnetite nanoparticles. The nanoparticles were prepared by controlled co-precipitation of Fe²⁺ and Fe³⁺ cations in ammonia at room temperature. Subsequently, the prepared Fe₃O₄ nanoparticles were coated with polyethyleneimine (PEI). The prepared materials were characterized by high-resolution transmission electron microscopy, X-ray diffraction, magnetometry, and zeta potential measurements. The prepared nanomaterials were used for magnetic harvesting of microalgae. The highest harvesting efficiencies were found for PEI-coated Fe₃O₄. The efficiency was pH-dependent. Higher harvesting efficiencies, up to 99%, were obtained in acidic solutions. The results show that magnetic harvesting can be significantly enhanced by PEI coating, as it increases the positive electrical charge of the nanoparticles. Most importantly, the flocculants can be prepared at room temperature, thereby reducing the production costs. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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20 pages, 1916 KiB

Open AccessArticle

Surface Coverage Simulation and 3D Plotting of Main Process Parameters for Molybdenum and Vanadium Adsorption onto Ferrihydrite

by Loredana Brinza

Nanomaterials 2022, 12(3), 304; https://doi.org/10.3390/nano12030304 - 18 Jan 2022

Cited by 3 | Viewed by 2106

Abstract

Ferrihydrite, FHY, was synthesized and characterized for morphology, mineralogy, surface area, hydrodynamic diameter and surface charge properties before molybdenum (Mo) and vanadium (V) adsorption. The potentiometric titration results showed first direct evidence that CO₂ affects FHY surface sites at pH 6–9. Beside [...] Read more.

Ferrihydrite, FHY, was synthesized and characterized for morphology, mineralogy, surface area, hydrodynamic diameter and surface charge properties before molybdenum (Mo) and vanadium (V) adsorption. The potentiometric titration results showed first direct evidence that CO₂ affects FHY surface sites at pH 6–9. Beside CO₂, particles concentration may affect surface properties with an impact on adsorption performance. Additional new adsorption simulation results on theoretical surface coverage vs. experimental results obtained at varying particles concentration help theoreticians and experimentalists to better estimate and apply anion adsorption processes to real environments and suggest that simulation may not always be entirely reliable. Uptake capacities obtained experimentally, varying pH, particles and metals concentrations, were plotted to assess their synergetic effect and derive trends for future process optimization. Adsorption kinetics and isotherms were also considered. Experimentally derived values for maximum uptake capacities (0.43 and 1.20 mmol g⁻¹, for Mo and V, respectively) and partitioning coefficients have applications, such as in making decisions for anions removal from wastewaters to achieve depollution efficiency or concentration required for effluents discharge and also implications in elements cycling from a geochemical perspective. In this work, the 3D plotting of the main adsorption process parameters obtained experimentally showed inter-correlations between significant process parameters that influence the adsorption process, and provides guidelines for its optimization and indicates that laboratory data can be transposed to real systems. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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10 pages, 1041 KiB

Open AccessArticle

Strong Crystallographic Influence on Spin Hall Mechanism in PLD-Grown IrO₂ Thin Films

by Pilar Jiménez-Cavero, Irene Lucas, Jorge Ara-Arteaga, M. Ricardo Ibarra, Pedro A. Algarabel and Luis Morellón

Nanomaterials 2021, 11(6), 1478; https://doi.org/10.3390/nano11061478 - 2 Jun 2021

Cited by 3 | Viewed by 2883

Abstract

Spin-to-charge conversion is a central process in the emerging field of spintronics. One of its main applications is the electrical detection of spin currents, and for this, the inverse spin Hall effect (ISHE) has become one of the preferred methods. We studied the [...] Read more.

Spin-to-charge conversion is a central process in the emerging field of spintronics. One of its main applications is the electrical detection of spin currents, and for this, the inverse spin Hall effect (ISHE) has become one of the preferred methods. We studied the thickness dependence of the ISHE in iridium oxide (IrO

_{2}

) thin films, producing spin currents by means of the spin Seebeck effect in

γ -

Fe

_{2}

O

_{3}

/IrO

_{2}

bilayers prepared by pulsed laser deposition (PLD). The observed ISHE charge current density, which features a maximum as a consequence of the spin diffusion length scale, follows the typical behaviour of spin-Hall-related phenomena. By fitting to the theory developed by Castel et al., we find that the spin Hall angle

θ_{SH}

scales proportionally to the thin film resistivity,

θ_{SH} \propto ρ_{c}

, and obtains a value for the spin diffusion length

λ_{IrO}_{2}

of

λ_{IrO}_{2} = 3.3 (7)

nm. In addition, we observe a negative

θ_{SH}

for every studied thickness and temperature, unlike previously reported works, which brings the possibility of tuning the desired functionality of high-resistance spin-Hall-based devices. We attribute this behaviour to the textured growth of the sample in the context of a highly anisotropic value of the spin Hall conductivity in this material. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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18 pages, 5209 KiB

Open AccessEditor’s ChoiceArticle

Fabrication, Microstructure and Colloidal Stability of Humic Acids Loaded Fe₃O₄/APTES Nanosorbents for Environmental Applications

by Lyubov Bondarenko, Erzsébet Illés, Etelka Tombácz, Gulzhian Dzhardimalieva, Nina Golubeva, Olga Tushavina, Yasuhisa Adachi and Kamila Kydralieva

Nanomaterials 2021, 11(6), 1418; https://doi.org/10.3390/nano11061418 - 27 May 2021

Cited by 21 | Viewed by 4429

Abstract

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) [...] Read more.

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) has been synthesized via the sol-gel method with and without establishing an inert atmosphere, and then it was tested in terms of humic acids (HA) loading applied as a multifunctional coating agent. The influence of ambient conditions on the microstructure, colloidal stability and HA loading of different silica-coated MNPs has been established. The XRD patterns show that the content of stoichiometric Fe₃O₄ decreases from 78.8% to 42.4% at inert and ambient atmosphere synthesis, respectively. The most striking observation was the shift of the MNPs isoelectric point from pH ~7 to 3, with an increasing HA reaching up to the reversal of the zeta potential sign as it was covered completely by HA molecules. The zeta potential data of MNPs can be used to predict the loading capacity for HA polyanions. The data help to understand the way for materials’ development with the complexation ability of humic acids and with the insolubility of silica gel to pave the way to develop a novel, efficient and magnetically separable adsorbent for contaminant removal. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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Review

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16 pages, 1351 KiB

Open AccessReview

Iron Oxide Nanoparticle-Based Hyperthermia as a Treatment Option in Various Gastrointestinal Malignancies

by Julian Palzer, Lea Eckstein, Ioana Slabu, Oliver Reisen, Ulf P. Neumann and Anjali A. Roeth

Nanomaterials 2021, 11(11), 3013; https://doi.org/10.3390/nano11113013 - 10 Nov 2021

Cited by 41 | Viewed by 3884

Abstract

Iron oxide nanoparticle-based hyperthermia is an emerging field in cancer treatment. The hyperthermia is primarily achieved by two differing methods: magnetic fluid hyperthermia and photothermal therapy. In magnetic fluid hyperthermia, the iron oxide nanoparticles are heated by an alternating magnetic field through Brownian [...] Read more.

Iron oxide nanoparticle-based hyperthermia is an emerging field in cancer treatment. The hyperthermia is primarily achieved by two differing methods: magnetic fluid hyperthermia and photothermal therapy. In magnetic fluid hyperthermia, the iron oxide nanoparticles are heated by an alternating magnetic field through Brownian and Néel relaxation. In photothermal therapy, the hyperthermia is mainly generated by absorption of light, thereby converting electromagnetic waves into thermal energy. By use of iron oxide nanoparticles, this effect can be enhanced. Both methods are promising tools in cancer treatment and are, therefore, also explored for gastrointestinal malignancies. Here, we provide an extensive literature research on both therapy options for the most common gastrointestinal malignancies (esophageal, gastric and colorectal cancer, colorectal liver metastases, hepatocellular carcinoma, cholangiocellular carcinoma and pancreatic cancer). As many of these rank in the top ten of cancer-related deaths, novel treatment strategies are urgently needed. This review describes the efforts undertaken in vitro and in vivo. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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