Oxyhydroxide Nanoparticles Research Articles

Superparamagnetic Relaxation in Ensembles of Ultrasmall Ferrihydrite Nanoparticles

The paper examines the impact of interparticle interactions on the superparamagnetic relaxation of ultrasmall nanoparticle ensembles, using Fe2O3∙nH2O iron oxyhydroxide (ferrihydrite) nanoparticles as an example. Two samples were analyzed: ferrihydrite of biogenic origin (with an average particle size of d ≈ 2.7 nm) with a natural organic shell, and a sample (with d ≈ 3.5 nm) that underwent low-temperature annealing, during which the organic shell was partially removed. The DC and AC magnetic susceptibilities (χ′(T), χ′′(T)) in a small magnetic field in the superparamagnetic (SPM) blocking region of the nanoparticles were measured. The results show that an increase in interparticle interactions leads to an increase in the SPM blocking temperature from 28 to 52 K according to DC magnetization data. It is shown that below the SPM blocking temperature, magnetic interactions of nanoparticles lead to the formation of a collective state similar to spin glass in bulk materials. The scaling approach reveals that the dynamics of correlated magnetic moments on the particle surface slow down with increasing interparticle interactions. Simulation of χ′′(T) dependence has shown that the dissipation of magnetic energy occurs in two stages. The first stage is directly related to the blocking of the magnetic moment of nanoparticles, while the second stage reflects the spin-glass behavior of surface spins and strongly depends on the strength of interparticle interactions.

Nitrogen-ion-irradiated defective tin oxyhydroxide nanoparticle anode for ultrafast and highly stable lithium-ion storage

High-performance lithium-ion batteries require high energy density, long cycle life, and fast (dis)chargeability. Despite several accomplishments in increasing capacity under normal operation, maintaining high capacity under fast charging and discharging remains a challenge. To achieve such performance, we have applied nitrogen-ion (N+) irradiation to an anode material comprising tin oxyhydroxide nanoparticles (Sn6O4(OH)4 NPs) active material, carbon black conducting agent, and polyvinylidene fluoride (PVDF) binder. Sn6O4(OH)4 NPs have high capacity and fair rate capability due to their layered structure with a large interlayer spacing of 0.455 nm and a small particle size of < 5 nm. N+ irradiation induces multiple defects including implanted N+ and oxygen vacancies in the anode material. The defects provide more Li-ion active sites in the Sn6O4(OH)4 NPs and lead to amorphization of carbon black as well as increasing the conductivities of Sn6O4(OH)4 NPs. Additionally, N+ irradiation brings about cross-linking of PVDF, enhancing the binding property. As a consequence, the N+-irradiated anode shows significantly improved performance: a capacity maintains 2306 mA h g−1 after 500 cycles at 0.5C and 1053 mA h g−1 after 300 cycles at 5C. Moreover, the anode exhibits outstanding rate capability even under ultrahigh-rate operation: 65.1 % capacity retention at 50C.

Sulfate enhances the adsorption and retention of Cu(II) and Zn(II) to dispersed and aggregated iron oxyhydroxide nanoparticles

The adsorption and retention of metal ions to nanoscale iron (hydr)oxides in aqueous systems is significantly influenced by prevailing environmental conditions. We examined the influence of sulfate, the second most common anion in seawater that is present in many other natural aquatic systems, on the adsorption and retention of Cu(II) and Zn(II) to synthetic iron oxyhydroxide nanoparticles (NPs) and their aggregates. Batch uptake experiments with monodisperse NPs and NPs aggregated by changes in pH, ionic strength, and temperature were conducted over sulfate concentrations ranging from 0 to 0.30 M. The introduction of 0.03 M sulfate significantly increased the initial adsorption and retention of Zn(II) and Cu(II) compared to sulfate-free conditions; with increasing sulfate >0.03 M, Zn(II) retention continuously increased, while Cu(II) retention was considerably more variable but increased slightly. NP aggregation, when induced by pH and ionic strength, was positively correlated with metal ion retention, while aggregation temperature was negatively correlated with both adsorption and retention. Aqueous geochemical modeling indicated that Zn(II) readily complexes with sulfate to form ZnSO4 (aq), but that stable aqueous CuSO4 species are uncommon. EXAFS spectroscopic analysis suggests structural incorporation of Zn(II) and Zn(II)-sulfate ternary surface complexation, while Cu(II) primarily forms inner-sphere bidentate surface complexes. Collectively, the effects of sulfate in both reducing surface charge repulsion, initiating ternary surface complexation, and enabling structural incorporation aid to enhance both metal adsorption and retention to iron oxyhydroxide NPs and their aggregates.

Neurotoxicity Profiling of Aluminum Salt-Based Nanoparticles as Adjuvants for Therapeutic Cancer Vaccine.

Therapeutic vaccines containing aluminum adjuvants have been widely used in the treatment of tumors due to their powerful immune-enhancing effects. However, the neurotoxicity of aluminum adjuvants with different physicochemical properties has not been completely elucidated. In this study, a library of engineered aluminum oxyhydroxide (EAO) and aluminum hydroxyphosphate (EAHP) nanoparticles was synthesized to determine their neurotoxicity in vitro. It was demonstrated that the surface charge of EAHPs and size of EAOs did not affect the cytotoxicity in N9, bEnd.3, and HT22 cells; however, soluble aluminum ions trigger the cytotoxicity in three different cell lines. Moreover, soluble aluminum ions induce apoptosis in N9 cells, and further mechanistic studies demonstrated that this apoptosis was mediated by mitochondrial reactive oxygen species generation and mitochondrial membrane potential loss. This study identifies the safety profile of aluminum-containing salts adjuvants in the nervous system during therapeutic vaccine use, and provides novel design strategies for their safer applications. SIGNIFICANCE STATEMENT: In this study, it was demonstrated that engineered aluminum oxyhydroxide and aluminum hydroxyphosphate nanoparticles did not induce cytotoxicity in N9, bEnd.3, and HT22 cells. In comparation, soluble aluminum ions triggered significant cytotoxicity in three different cell lines, indicating that the form in which aluminum is presenting may play a crucial role in its safety. Moreover, apoptosis induced by soluble aluminum ions was dependent on mitochondrial damage. This study confirms the safety of engineered aluminum adjuvants in vaccine formulations.

Charged-Particle-Irradiated Tin Oxyhydroxide Nanoparticle Anodes for Lithium-Ion Batteries

Metal oxyhydroxides have been promising ceramic materials in miscellaneous electrochemical fields due to their multiple redox states, interlayer conductivity, and structural stability as well as electrocatalytic activity. When applied to anode active materials for secondary batteries, particularly lithium-ion batteries, metal oxyhydroxides have a much larger theoretical capacity than that of commercial graphite by conversion and/or alloying reactions with lithium ions rather than intercalation. However, the inevitable volume variation of metal oxyhydroxides during battery operation impinges other primary components in anode materials such as binders and conducting agents, leading to pulverizing the anode materials. Moreover, metal oxyhydroxides are not electrically conductive so much that electrochemical reactions cannot be facilitated efficiently during cycling. Accordingly, many efforts, for example, nanostructuring, constructing hierarchical configurations or hollow structures, and hybridization with carbonaceous materials, have been attempted to overcome the limitations of metal oxyhydroxide anode active materials. In addition, crystal defects in anode materials are greatly helpful to promote electrochemical activity by tuning electronic and chemical properties. Hydrogen annealing, plasma treatment, and chemical reduction method are common approaches to inducing a large number of defects in materials, but they are generally employed at high temperatures or under controlled-pressure circumstances. Therefore, we deploy charged particle irradiation to generate numerous defects in the metal oxyhydroxide anode materials. Incident charged particles interact with a lot of atoms in the anode materials, causing atomic displacement. As a result of the displacement, diverse kinds of defects are produced, which change the electronic and chemical structures of the anode materials. Charged particle irradiation introduces a high density of defects and selective defect types for short time at room temperature. Amorphization is also induced by charged particle irradiation, which is beneficial to improve the electrochemical performance of metal oxyhydroxide anode materials. Herein, we first synthesize tin oxyhydroxide nanoparticles (SnOOH NPs), one of the potential anode active materials using simple nanostructuring, via an electrochemical route, anodization. Anodization is a very fast and concise process to obtain nanostructured metal oxides as well as NPs. Electrodes with SnOOH NPs are irradiated with various charged particles including electrons, protons, helium ions, nitrogen ions, and argon ions, and the irradiation effects are investigated. SnOOH NP anodes irradiated with each type of charged particle show different electrochemical performances from each other, but all of the irradiated SnOOH NP anodes exhibit enhanced discharge capacity or cycle life compared with a pristine SnOOH NP anode. Plausible mechanisms of the irradiation effects depending on charged particles are also proposed. Charged particle irradiation can be utilized for not only metal oxyhydroxides but any kind of ceramic materials in diverse applications including lithium-ion batteries. Figure 1

Magnesium oxyhydroxide nanoparticles: Synthesis, characterization and evaluation of their genotoxicity in Vicia faba L.

Magnesium oxyhydroxide nanoparticles (MgO/Mg(OH)2-NPs) were synthesized by a chemical route and their toxicity were evaluated using Vicia faba L. The obtained solids were characterized using visible infrared and ultraviolet spectroscopy, X-ray diffraction (XRD), electron microscopy and surface area by the BET method. The results indicated the presence of two phases: periclase (MgO) and brucite (Mg(OH)2). These MgO/Mg(OH)2 were <50 nm in size, with band gap energy between 5.95 and 6.12 eV and Urbach energy of ∼340 meV. To determine toxicological endpoints, such as mitotic index (MI) and micronucleus induction (MN), Vicia faba L. root tip cells were treated with suspensions containing concentrations of 12.5, 25, 50 and 100 mg/L of MgO/Mg(OH)2-NPs. The results of the toxicological evaluation showed a decrease in MI in the roots of Vicia faba L. exposed to NPs and a positive correlation between the percentage of cells with MN and the concentrations of MgO/Mg(OH)2-NPs used.

Biosynthesis and characterization of α-FeOOH nanoparticles using Isabella grape (Vitis Labrusca L.) extract

The advancement of environmentally sustainable and eco-friendly approaches to nanoparticle synthesis has gained significant importance in analytical chemistry. This research examined the green synthesis of iron oxyhydroxide nanoparticles, utilizing Vitis labrusca L. extract as both a reducing and stabilizing agent. The application of this natural extract offers an environmentally friendly alternative to conventional chemical synthesis techniques and is expected to meet the growing demand for sustainable applications. The synthesized iron oxyhydroxide nanoparticles were characterized using advanced techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR), to verify their composition and structure. The findings reveal the successful synthesis of iron oxyhydroxide nanoparticles with a uniform size distribution and excellent stability.

High mass loading paper-based electrode material with cellulose fibers under coordination of zirconium oxyhydroxide nanoparticles and sulfosalicylic acid

With the rapid expansion of the flexible electronics market, it is critical to develop high-performance flexible energy storage electrode materials. Cellulose fibers, which are sustainable, low cost, and flexible, fully meet the requirements of flexible electrode materials, but they are electrically insulating and cause a decrease in energy density. In this study, high-performance paper-based flexible electrode materials (PANI:SSA/Zr-CFs) were prepared with cellulose fibers and polyaniline. A high mass loading of polyaniline was wrapped on zirconia hydroxide-modified cellulose fibers under metal-organic acid coordination through a facile in situ chemical polymerization process. The increase in mass loading of PANI on cellulose fibers not only improves the electrical conductivity but also enhances the area-specific capacitance of the flexible electrodes. The results of electrochemical tests show that the area specific capacitance of the PANI:SSA/Zr-CFs electrode is 4181 mF/cm2 at 1 mA/cm2, which is more than two times higher than that of the electrode with PANI on pristine CFs. This work provides a new strategy for the design and manufacture of high-performance flexible electronic electrodes based on cellulose fibers.

Gum Arabic-Stabilized Ferric Oxyhydroxide Nanoparticles for Efficient and Targeted Intestinal Delivery of Bioavailable Iron

Nanostructured iron(III) compounds are promising food fortificants with desirable iron bioavailability and food compatibility. Here, gum arabic (GA) solubilized 252 mg of iron(III) per g at neutral pH in the form of GA-stabilized ferric oxyhydroxide nanoparticles (GA-FeONPs) with Z-average size of 142.7 ± 5.9 nm and ζ-potential of -20.50 ± 1.25 mV. Calcein-fluorescence-quenching assay revealed well-absorbed iron from GA-FeONPs by polarized Caco-2 cells due to efficient macropinocytic internalization and asialoglycoprotein receptor-mediated specific endocytosis facilitated by the polypeptide and arabinogalactan fractions of GA, respectively, with endocytosed GA-FeONPs being in part basolaterally transcytosed and in another part degraded into cellular labile iron pool. GA-FeONPs showed good colloidal stability under varied pH, gastrointestinal, thermal processing, and spray/freeze drying conditions and displayed remarkably weaker pro-oxidant activity than FeSO4 in glyceryl trilinoleate emulsion (P < 0.05). Oral pharmacokinetics unveiled desirable iron bioavailability of GA-FeONPs relative to FeSO4, i.e., 124.27 ± 5.91% in aqueous solution and 161.64 ± 5.01% in milk. Overall, GA-FeONPs are a promising novel iron fortificant with food-compatible, efficient, and targeted intestinal iron delivery and sustained iron-release properties.

Effect of goethite (α-FeOOH) nanoparticles on the surface properties and flotation behavior of chalcopyrite

Chalcopyrite flotation is selectively depressed by oxidation treatment. The presence of ferric oxyhydroxide on the surface of chalcopyrite after oxidation treatment is a key factor in depressing chalcopyrite flotation. However, there is no concrete evidence that ferric oxyhydroxide has a depressing effect. In addition, the effectiveness of this depressing effect could be enhanced by directly applying ferric oxyhydroxide nanoparticles. This study investigated the effect of goethite (α-FeOOH) nanoparticles on the surface properties and flotation behavior of chalcopyrite. α-FeOOH nanoparticles were produced through chemical precipitation followed by hydrothermal treatment. The crystalline structure of irregular rice grain-shaped α-FeOOH nanoparticles was confirmed by the X-ray diffraction pattern and scanning electron microscope image. Micro-flotation experiments showed that chalcopyrite recovery decreased significantly from 93 % to 13 % when 30 mg/L α-FeOOH nanoparticles was used. This flotation result demonstrated the potential of α-FeOOH nanoparticles as a nanodepressant for the flotation of chalcopyrite. These nanoparticles physically adsorbed on the chalcopyrite surface and rendered its surface hydrophilic, thereby reducing the chalcopyrite flotation recovery. The attractive electrostatic force between the positively charged α-FeOOH nanoparticles and the negatively charged chalcopyrite surface is likely responsible for the adsorption of α-FeOOH nanoparticles on chalcopyrite.

Defect-rich ultrafine amorphous tin oxyhydroxide nanoparticle anode for high-performance lithium-ion batteries

Metal oxyhydroxide nanostructures are attractive anode materials for lithium-ion batteries (LIBs) because of their appreciable theoretical capacity. In their amorphous phase they can greatly relieve volume changes during cycling, enhancing cycle stability. Here, we successfully produce amorphous tin oxyhydroxide nanoparticles (a-SnOOH NPs) with sizes of less than 5 nm using a facile electrochemical anodization method. Plentiful oxygen vacancies (VOs) are generated in the NPs by simply introducing glycerol into the electrolyte. The numerous defects further facilitate the electrochemical kinetics of the a-SnOOH NPs with rich VOs (a-SnOOH/VO NPs), resulting in better cell performance. With the synergetic combination of amorphous nature and abundant defect sites, the a-SnOOH/VO NP anode for LIBs exhibits a considerable initial discharge capacity of 2171.3 mAh/g at a current rate of 0.2 C and retains a high reversible capacity with a coulombic efficiency of 98.4% after 300 cycles. The ultrafine particles also deliver exceptional rate capability with a large capacity of 641.9 mAh/g even at a high current rate of 20 C.

Mineral Nanoparticle Aggregation Alters Contaminant Transport under Flow.

Iron oxyhydroxide nanoparticle reactivity has been widely investigated, yet little is still known on how particle aggregation controls the mobility and transport of environmental compounds. Here, we examine how aggregates of goethite (α-FeOOH) nanoparticle deposited on 100-300 μm quartz particles (GagCS) alter the transport of two emerging contaminants and two naturally occurring inorganic ligands-silicates and phosphates. Bromide tracer experiments showed no water fractionation into mobile and immobile water zones in an individual goethite-coated sand (GCS) column, whereas around 10% of the total water was immobile in a GagCS column. Reactive compounds were, in contrast, considerably more mobile and affected by diffusion-limited processes. A new simulation approach coupling the mobile-immobile equation with surface complexation reactions to surface reactive sites suggests that ∼90% of the binding sites were likely within the intra-aggregate zones, and that the mass transfer between mobile and immobile fractions was the rate-limited step. The diffusion-controlled processes also affected synergetic and competitive binding, which have otherwise been observed for organic and inorganic compounds at goethite surfaces. These results thereby call for more attention on transport studies, where tracer or conservative tests are often used to describe the reactive transport of environmentally relevant molecules.

Efficient and durable S-doped Ni/FeOOH electrocatalysts for oxygen evolution reactions.

It is important to develop highly efficient and durable Earth-abundant oxygen evolution reaction (OER) electrocatalysts by an energy- and time-saving strategy. Herein, a facile strategy was used to synthesize S-doped nickel-iron oxyhydroxide (S-Ni/FeOOH) nanoparticles on nickel-iron foam (NFF) (S-Ni/FeOOH@NFF), which exhibits a striking enhancement of OER performance compared to Ni/FeOOH@NFF. The free-standing S-Ni/FeOOH@NFF electrode possesses a low overpotential of 229 mV at a current density of 10 mA cm-2, which is 180 mV lower than that of Ni/FeOOH@NFF. In addition, the electrode was also remarkably stable. The current density still remains at 95% after 150 h at a high current density of 100 mA cm-2.

One-pot gamma radiolysis synthesis of a graphene oxide-supported cobalt oxyhydroxide electrocatalyst for oxygen reduction reaction

In this work, high-performance non-platinum group metal (non-PGM) electrocatalysts for oxygen reduction reaction (ORR) are synthesized from graphene oxide-supported cobalt oxyhydroxide nanoparticles via a one-pot gamma radiolysis method. Investigations are conducted into how cobalt precursor concentration and the amount of gamma radiation affect the electrocatalysts' ability to perform oxygen reduction reactions as well as their physicochemical characteristics. Results show that the electrocatalyst prepared with the 0.1 M cobalt precursor and gamma radiation dose of 25 kGy has an advantage over the other samples in displaying good oxygen reduction activity. The characterization results of the synthesized electrocatalyst obtained through field-emission scanning electron microscopy–energy dispersive spectroscopy and X-ray diffraction combined with Rietveld refinement confirm the presence of nanosized cobalt oxyhydroxide particles that are evenly distributed on the surface of graphene oxide. ORR results show that the electrocatalyst has an onset potential of 0.90 V (vs. the reversible hydrogen electrode or RHE), a half-wave potential of 0.75 V (vs. RHE), a low peroxide yield of 7.08%, and an electron transfer number of 3.86, indicating a four-electron transfer path-way in the ORR process. This work provides an alternative facile means to mass-produce competitive non-PGM ORR electrocatalysts for fuel cell applications.

A Comprehensive Study of Synthesis and Analysis of Anisotropic Iron Oxide and Oxyhydroxide Nanoparticles.

One-dimensional anisotropic nanoparticles are of great research interest across a wide range of biomedical applications due to their specific physicochemical and magnetic properties in comparison with isotropic magnetic nanoparticles. In this work, the formation of iron oxides and oxyhydroxide anisotropic nanoparticles (ANPs) obtained by the co-precipitation method in the presence of urea was studied. Reaction pathways of iron oxide and oxyhydroxide ANPs formation are described based on of X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and pulse magnetometry studies. It is shown that a nonmonotonic change in the Fe3O4 content occurs during synthesis. The maximum content of the Fe3O4 phase of 47.4% was obtained at 12 h of the synthesis. At the same time, the reaction products contain ANPs of α-FeOOH and submicron isotropic particles of Fe3O4, the latter formation can occur due to the oxidation of Fe2+ ions by air-oxygen and Ostwald ripening processes. A subsequent increase in the synthesis time leads to the predominant formation of an α-FeOOH phase due to the oxidation of Fe3O4. As a result of the work, a methodological scheme for the analysis of iron oxide and oxyhydroxide ANPs was developed.

Structure and electrical potential of calcium phosphate coatings modified with aluminum oxyhydroxide nanoparticles

The effect of the introduction of charged aluminum oxyhydroxide (AO) nanoparticles into the porous coatings from calcium phosphate formed by micro-arc oxidation on their electrical potential and structure was studied. The modification resulted in changes in the morphology and elemental composition of the coatings. The selection of coating functionalization parameters resulted in obtaining homogeneously distributed aluminum oxyhydroxide nanoparticles in the form of agglomerates, providing the maximum change in the electrical potential of the coatings. An increase in the duration of ultrasonic dispersion (USD) of initial AlN powder suspension from 10 to 60 min and an increase in the surface roughness of the coatings, parameter Ra, from 3.5 to 5.5 µm led to an increase in the surface electrical potential from −85 to −35 mV. At the same time, the aluminum content in the coating decreased from 3 to 1 at.% with an increase in the duration of USD of the AlN powder suspension from 10 to 60 minutes. The introduction of aluminum oxyhydroxide nanoparticles into the coating contributed to an improvement in corrosion properties, namely, an increase in the corrosion potential from 0.1 to 0.2 mV and a decrease in the corrosion current from 2.5 ∙10−9 to 1.1·10−9 A ∙ cm2.

Transformation of used aluminium foil food container into AlOOH nanoflakes with high catalytic activity in anionic azo dye reduction

Synthesis of aluminium-based nanomaterials from aluminium-waste has received huge attention in current scientific research. Herein, an attempt was made to convert aluminium foil food container into aluminium oxyhydroxide (AlOOH) nanoparticles by a precipitation method. X-ray diffraction (XRD), spectroscopic and electron microscopic studies were employed to characterize impure AlOOH (containing sodium chloride, NaCl) and pure AlOOH samples. The band gap (Eg) of AlOOH nanoparticles was found to be 4.5 eV. The catalytic potential of AlOOH samples was evaluated using reduction of methyl orange (MO) and Eriochrome black T (EBT) dyes. Impure AlOOH nanoparticles could reduce 99.8% of MO and EBT dye within 4 min and 3 min respectively. Effect of the AlOOH dosage and NaBH4 concentration on catalytic reduction was determined. Used aluminium foil food container-derived AlOOH nanoparticles will become a low-cost and sustainable catalyst in the catalytic treatment of azo dye contaminated waters.

Triple action of FeCl3-assisted hydrothermal treatment of digested sludge for deep dewatering

In this study, a FeCl3-assisted hydrothermal treatment (HTT) process under mild conditions (90 °C–130 °C) was developed for deep dewatering of anaerobically digested sludge. HTT of sludge at 90 °C–130 °C with 4%–6% Fe3+ ions loading based on total sludge solids followed by mechanical dewatering reduced sludge water content from 82% to 38%–53% and sludge weight by 62%–72%. The treatment increased the flowability of sludge through reduction of apparent viscosity and disintegration of colloidal forces between sludge particles. This study unveiled that FeCl3-assisted HTT process had three mechanisms for improving sludge dewaterability and flowability. The treatment hydrolysed sludge flocs in the presence of Lewis acid FeCl3 and high temperature (90–130 °C). Fe3+ ions also improved dewaterability through the formation of double electric layers and neutralisation of surface negative charges, leading to flocculation of sludge flocs. More importantly, the hydrolysed sludge components produced during HTT process acted as reducing agents and led to in-situ generation of iron oxyhydroxide nanoparticles through reduction-oxidation reactions, further enhancing flocculation/co-precipitation of sludge flocs. The treatment reduced EPS content and changed conformational structures of EPS proteins by breaking down hydrogen bond-maintaining α-helix which led to a loose EPS protein structure and enhanced hydrophobicity and flocculability. Furthermore, the FeCl3-assisted treatment promoted immobilisation of the majority of heavy metals in the sludge matrix through co-precipitation/complexation reactions with iron species and organic/inorganic matters. This indicates that the FeCl3-assisted treatment reduced direct toxicity/bioavailability of the majority of heavy metals and the treated sludge may be suitable for land application. Overall, this study provides new insights into mechanism of FeCl3-assisted HTT process for dewaterability of anaerobically digested sludge and immobilisation of heavy metals.

Iron oxide and iron oxyhydroxide nanoparticles impair SARS-CoV-2 infection of cultured cells

BackgroundCoronaviruses usually cause mild respiratory disease in humans but as seen recently, some human coronaviruses can cause more severe diseases, such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the global spread of which has resulted in the ongoing coronavirus pandemic.ResultsIn this study we analyzed the potential of using iron oxide nanoparticles (IONPs) coated with biocompatible molecules like dimercaptosuccinic acid (DMSA), 3-aminopropyl triethoxysilane (APS) or carboxydextran (FeraSpin™ R), as well as iron oxyhydroxide nanoparticles (IOHNPs) coated with sucrose (Venofer®), or iron salts (ferric ammonium citrate -FAC), to treat and/or prevent SARS-CoV-2 infection. At non-cytotoxic doses, IONPs and IOHNPs impaired virus replication and transcription, and the production of infectious viruses in vitro, either when the cells were treated prior to or after infection, although with different efficiencies. Moreover, our data suggest that SARS-CoV-2 infection affects the expression of genes involved in cellular iron metabolism. Furthermore, the treatment of cells with IONPs and IOHNPs affects oxidative stress and iron metabolism to different extents, likely influencing virus replication and production. Interestingly, some of the nanoparticles used in this work have already been approved for their use in humans as anti-anemic treatments, such as the IOHNP Venofer®, and as contrast agents for magnetic resonance imaging in small animals like mice, such as the FeraSpin™ R IONP.ConclusionsTherefore, our results suggest that IONPs and IOHNPs may be repurposed to be used as prophylactic or therapeutic treatments in order to combat SARS-CoV-2 infection.Graphical

Carbothermal Shock Synthesis of High Entropy Oxide Catalysts: Dynamic Structural and Chemical Reconstruction Boosting the Catalytic Activity and Stability toward Oxygen Evolution Reaction

AbstractMixed transition‐metals (TM) based catalysts have shown huge promise for water splitting. Conventional synthesis of nanomaterials is strongly constrained by room‐temperature equilibria and Ostwald ripening. Ultra‐fast temperature cycling enables the synthesis of metastable metallic phases of high entropy alloy nanoparticles, which later transform to oxide/hydroxide nanoparticles upon use in aqueous electrolytes. Herein, an in situ synthesis of non‐noble metal high entropy oxide (HEO) catalysts on carbon fibers by rapid Joule heating and quenching is reported. Different compositions of ternary to senary (FeNiCoCrMnV) HEO nanoparticles show higher activity towards catalyzing the oxygen evolution reaction (OER) compared to a noble metal IrO2 catalyst. The synthesized HEO also show two orders of magnitude higher stability than IrO2, due to stronger carbide‐mediated intimacy with the substrate, activated through the OER process. Alloying elements Cr, Mn and V affect OER activity by promoting different oxidation states of the catalytically active TM (Fe, Ni and Co). Dissolution of less stable elements (Mn, V and Cr) leads to enhancements of OER activity. Dynamic structural and chemical perturbations of HEO oxide nanoparticles activate under OER conditions, leading to enlargement in ECSA by forming mixed single atom catalysts and ultra‐fine oxyhydroxide nanoparticles HEOs.