Iron Oxide Microspheres Research Articles

Upscaling waste human hairs into micro/nanorobots for adsorptive removal of micro/nanoplastics

The escalating spread of micro/nanoplastics (MPs/NPs), originating from plastic waste fragmentation in the environment, is a growing global concern with detrimental effects on aquatic ecosystems. Previous methods for MPs/NPs treatment/removal poses significant challenges such as filtration, sedimentation efficiency, potential introduction of additional pollutants and expensive fabrication steps. In the current work, for the first-time keratin (KER)-based biohybrid micro/nanorobots obtained by facile decorations of iron-oxide microspheres with magnetic capabilities designed to dynamically remove (MPs/NPs) through various chemical/physical interactions, precise magnetic actuation, and improved surface functionalities. By integrating iron-oxide microspheres, keratin biohybrids achieve accurate motility and manipulation via external magnetic field regulation. This fuel free keratin magnetic micro/nanorobots (KMNRs) exhibit notable adsorptive removal efficiencies of 95% and 82% for (MPs/NPs) in water, offering diverse potentiality. Additionally, KMNRs demonstrated excellent recyclability, enhancing their sustainability. With eco-friendly, cost-effective, and real-world application attributes, designed KMNRs present an appealing approach to addressing MPs/NPs pollution.

Ultrafast Charging/Discharging and Highly Stable Non-aqueous Iron-Ion Batteries using Iron oxide (Fe3O4) Microspheres as Efficient Cathode Material

Rechargeable iron-ion batteries (RIIBs) are considered one of the alternatives to lithium-ion batteries (LIBs) due to their high volumetric energy density and low-cost fabrication in ambient conditions. A crucial aspect...

Synthesis of Fe2O3@SnO2 Core‐shell Nanocomposites via Thermal Decomposition Route and their Application as an Adsorbent

AbstractIn the current study, a thermal decomposition approach has been used to synthesize Fe2O3@SnO2 core‐shell nanocomposites in which Fe2O3 microsphere is the core and SnO2 is the shell. The thickness of shell (SnO2) is altered by varying amount of tin chloride pentahydrate (precursor of SnO2). Various characterization techniques were used to prove successful formation of Fe2O3@SnO2 core‐shell nanocomposites. XRD results confirm the presence of SnO2, α‐Fe2O3, and Fe3O4 in the calcined Fe2O3@SnO2 core‐shell nanocomposites. FE‐SEM and TEM studies reveal uniform deposition of SnO2 nanoparticles over the iron oxide microspheres. XPS analysis demonstrates the presence of Sn4+, Fe2+, Fe3+, and O2− in the Fe2O3@SnO2 core‐shell nanocomposites. Optical studies show that the Fe2O3@SnO2 core‐shell nanocomposites absorb in UV and visible regions. M−H studies on Fe2O3@SnO2 core‐shell nanocomposites indicate weak ferromagnetic and superparamagnetic behaviour of the nanocomposites at 5 K and 300 K, respectively. From M−T measurements, pure α‐Fe2O3 shows characteristic Morin transition (Tm), but the Fe2O3@SnO2 core‐shell nanocomposites do not show such transition. The Fe2O3@SnO2 core‐shell nanocomposites were explored as adsorbent for the removal of congo red (CR) from an aqueous solution.

Development of high reusability trifunctional polyethersulfones microspheres for the removal of methyl orange

This study focused on the synthesis of trifunctional microspheres with adsorption, degradation, and magnetic responsive properties. Firstly, polyethersulfones (PES) encapsulated poly(diallyldimethyl ammonia) chloride (PDDA) functionalized iron oxide (Fe3O4) microspheres were produced via phase inversion method. The PDDA/Fe3O4-PES microspheres were further coated with Fe3O4 nanoparticles (NPs) on the surface to provide the degradation ability to the formed c-PDDA/Fe3O4-PES microspheres. Characterization results such as FTIR analysis confirmed the coating of PDDA on Fe3O4 NPs, while the TGA analysis proved the excellent thermal stability of microspheres after the incorporation of PDDA/Fe3O4 NPs. BET specific surface area of microspheres was measured at 13.90 m2/g. Besides, the pH drift method confirmed the presence of positive charge on microspheres surface, which is important for the removal of anionic pollutants. Moreover, porous structure of microspheres was also observed under SEM. Formulation study was also carried out to investigate the suitable concentration for the synthesis of microspheres, including the concentration of PES polymer (1–20 wt%), the loading of PDDA/Fe3O4 NPs (1–5 wt%), and the concentration of polyethylene glycol (PEG) (1–20 wt%). The microspheres synthesized from different formulations were subjected to the batch removal of methyl orange (MO). Results showed that a 72.53 % removal of MO can be obtained under the following microspheres synthesis formulations: 10wt% of PES polymer, 2 wt% of PDDA/Fe3O4 NPs, and 5 wt% of PEG polymer. Lastly, the c-PDDA/Fe3O4-PES microspheres also demonstrated an excellent reusability as compared to pure PES microspheres. The c-PDDA/Fe3O4-PES microspheres could be reused up to 5 cycles without the need of regeneration while still maintaining high MO removal efficiency.

Construction of a Microfluidic Platform With Core-Shell CdSSe@ZnS Quantum Dot-Encoded Superparamagnetic Iron Oxide Microspheres for Screening and Locating Matrix Metalloproteinase-2 Inhibitors From Fruits of Rosa roxburghii.

The microfluidic platform is a versatile tool for screening and locating bioactive molecules from functional foods. Here, a layer-by-layer assembly approach was used to fabricate core-shell CdSSe@ZnS quantum dot encoded superparamagnetic iron oxide microspheres, which served as a carrier for matrix metalloproteinase-2. The matrix metalloproteinase-2 camouflaged magnetic microspheres was further incorporated into a homemade microfluidic platform and incubated with extracts of fruits of Rosa roxburghii. The flow rate of the microfluidic platform was tuned. The major influencing parameters on ligand binding, such as dissociate solvents, incubation pH, ion strength, temperature, and incubation time were also optimized by using ellagic acid as a model compound. The specific binding ligands were sent for structure elucidation by mass spectrometry. The absolute recovery of ellagic acid ranged from 101.14 to 102.40% in the extract of R. roxburghii under the optimal extraction conditions. The linearity was pretty well in the range of 0.009–1.00 mg·ml−1 (R2 = 0.9995). The limit of detection was 0.003 mg·ml−1. The relative SDs of within-day and between-day precision were <1.91%. A total of thirteen ligands were screened out from fruits of R. roxburghii, which were validated for their inhibitory effect by enzyme assay. Of note, eleven new matrix metalloproteinase-2 inhibitors were identified, which may account for the antitumor effect of fruits of R. roxburghii.

TEMPO-assisted Glycothermal Synthesis of Monodisperse Magnetic Iron Oxide Microspheres with Enhanced Adsorption Capacity

Direct synthesis of functionalized magnetic iron oxide (MIO) microspheres would promote their application as magnetic adsorbents, catalysts and bio-carriers. Herein monodisperse MIO microspheres of...

In-situ constructing uniform polymer network for iron oxide microspheres: A novel approach to improve the cycling stability of the conversion electrodes through chemical interaction

Electrochemical conversion reaction provides potential high-capacity anode materials for Li-ion and Na-ion batteries. However, the inferior cyclability is seriously hindering their applications. Herein, a novel strategy is introduced to improve the performance of conversion-type Fe2O3-AHP composite by using an organic amino-hyperbranched polymer additive. The amino groups of polymers could coordinate with Fe3+ through chemical interaction, and make Fe2O3 particles self-assemble into unique microspheres in solvothermal process. Moreover, the polymer additive in-situ constructs 3D uniform elastic frame work on molecular level in Fe2O3-AHP composite, which could accommodate the volume change and stabilize the Fe2O3 structure during lithiation/delithiation or sodiation/desodiation processes. Therefore, compared with Fe2O3-AHP-500 in which AHP was removed by heat treatment, the Fe2O3-AHP microspheres exhibit excellent long-term Li-storage (98.3% capacity retention rate after 1000 cycles at 2.0 A g−1) and Na-storage cyclabilities and maintain the integrity of microsphere structure after cycling. Furthermore, the polymer additive makes the Fe2O3-AHP microsphere have plenty of nanopores, which facilitate electrolyte infiltration and ion diffusion and thus enhance the kinetic performance. The present study highlights a novel strategy of in-situ construction of stable network on molecular level using polymer additive via strong chemical interaction, which delivers inspiration optimizing the long-term cyclability of conversion-type materials.

The Investigation of Mixed Ferrofluids Containing Iron Oxide nanoparticles and Microspheres

The aim of the present work is the synthesis and characterization of iron oxide (Fe3O4) nanoparticles. These nanoparticles are coated with oleic acid and polyvinyl butyral and mixed with microspheres and further developed ferrofluids with silicon oil. Studies of the performance of the nanoparticles in these ferrofluids with and without coating agents were carried out. The nanoparticles were synthesized using the chemical co‐precipitation technique and coated with oleic acid and polyvinyl butyral, and it further mixed with microsphere ferrofluids and developed using silicon oil. The prepared Fe3O4 nanoparticles and their coated forms of oleic acid and polyvinyl butyral were mixed with microspheres; furthermore, ferrofluids were developed with silicon oil. All forms of these ferrofluids are characterized for morphology and phase purity (SEM, XRD, and FTIR). The iron oxide (Fe3O4) nanoparticles have shown different magnetic properties, differentiating macroscopic iron oxide in suspended particles. The ratio of surface to volume increases along with the decrease in atomic size, essential for assessing the surface morphological properties. The magneto‐rheological (MR) fluids were determined, and shear stress of Expancel microsphere mixed iron oxide nanoparticle with and without them was found almost equal. However, the ferrofluid with PVB coated nanoparticles and microspheres emerged as a stable rheological ferrofluid, sustaining high shear stress and low viscosity with increasing shear rate. Also, shear rates up to 650 s−1 have been observed, showing very high shear stress withstanding capacity. The stability and performance of the magnetic colloidal ferrofluids depend on the thermal contribution and the balance between attractive/repulsive interactions.

Paramagnetic Clusters of Mn3(O2CCH3)6(Bpy)2 in Polyacrylamide Nanobeads as a New Design Approach to a T1- T2 Multimodal Magnetic Resonance Imaging Contrast Agent.

There is an increasing need for gadolinium-free magnetic resonance imaging (MRI) contrast agents, particularly for patients suffering from chronic kidney disease. Using a cluster-nanocarrier combination, we have identified a novel approach to the design of biomedical nanomaterials and report here the criteria for the cluster and the nanocarrier and the advantages of this combination. We have investigated the relaxivity of the following manganese oxo clusters: the parent cluster Mn3(O2CCH3)6(Bpy)2 (1) where Bpy = 2,2'-bipyridine and three new analogs, Mn3(O2CC6H4CH═CH2)6(Bpy)2 (2), Mn3(O2CC(CH3)═CH2)6(Bpy)2 (3), and Mn3O(O2CCH3)6(Pyr)2 (4) where Pyr = pyridine. The parent cluster, Mn3(O2CCH3)6(Bpy)2 (1), had impressive relaxivity ( r1 = 6.9 mM-1 s-1, r2 = 125 mM-1 s-1) and was found to be the most amenable for the synthesis of cluster-nanocarrier nanobeads. Using the inverse miniemulsion polymerization technique (1) in combination with the hydrophilic monomer acrylamide, we synthesized nanobeads (∼125 nm diameter) with homogeneously dispersed clusters within the polyacrylamide matrix (termed Mn3Bpy-PAm). The nanobeads were surface-modified by co-polymerization with an amine-functionalized monomer. This enabled various postsynthetic modifications, for example, to attach a near-IR dye, Cyanine7, as well as a targeting agent. When evaluated as a potential multimodal MRI contrast agent, high relaxivity and contrast were observed with r1 = 54.4 mM-1 s-1 and r2 = 144 mM-1 s-1, surpassing T1 relaxivity of clinically used Gd-DTPA chelates as well as comparable T2 relaxivity to iron oxide microspheres. Physicochemical properties, cellular uptake, and impacts on cell viability were also investigated.

The morphology and internal structure of natural and man-made iron oxide microspheres

The morphology and internal structure of natural and man-made iron oxide microspheres

Developing new adsorptive membrane by modification of support layer with iron oxide microspheres for arsenic removal

Arsenic-contaminated water has significant adverse impacts on human health and ecosystems. We developed a new adsorptive membrane by modifying the porous support layer of a phase inversion formed membrane for arsenic removal. Iron oxide (Fe3O4) microspheres were immobilized in the support layer of the membrane by reverse filtration, followed by dopamine polymerization. The prepared adsorptive membrane was compared with a virgin membrane without Fe3O4 microspheres and a Fe3O4 blended membrane in terms of membrane structures and separation performance. The adsorptive membrane prepared by our new method had comparable water permeability and rejection performance with the virgin membrane without Fe3O4 microspheres, but higher rejection performance and dynamic adsorption capacity than the membrane prepared by the conventional blending method. Both static and dynamic adsorption modes were used to evaluate the adsorption performance of the membranes. Our new adsorptive membrane also had excellent regeneration performance. After three regeneration cycles, the membrane was still capable of treating more than 2 tons of As-contaminated water/m2. The adsorptive membrane of 1 m2 could treat over 7 tons of water to the drinking water standard in terms of arsenic concentration during three regeneration cycles. Therefore, our adsorptive membrane may pave a new way for arsenic removal from water and ensuring drinking water security.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates.

Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances.

Superparamagnetic PLGA–iron oxide microspheres as contrast agents for dual-imaging and the enhancement of the effects of high-intensity focused ultrasound ablation on liver tissue

Efforts have been made to develop a multifunctional platform that could provide both diagnostic information and a therapeutic effect.

Bacterial origin of iron-rich microspheres in Miocene mammalian fossils

In their taphonomic study of a Cretaceous dinosaur fossil from the Gobi desert (Mongolia), Kremer et al. (2012) noted that the histological sections of this fossil preserved within their core iron oxide microspheres containing carbonaceous matter. They interpreted the carbonaceous nature of these structures as organic matter and suggested a microbial origin (probably bacterial) for the structures. Microspheres, similar both in composition and shape, have been identified in fossils from Cerro de la Garita, a Miocene mammalian site in Teruel, Spain. In the latter case, compact bone was also attacked by terrestrially associated bacteria (microscopic focal destruction [MFD]) which were enriched in iron and gives support to the idea that bacteria acted as the biological agent for iron precipitation during soft tissue decomposition in the early stages of bone diagenesis. Subsequent diagenetic episodes of mineralization related to the environmental context differ between these two sites; calcite precipitation at the palaeo-lakeshore of Cerro de la Garita and calcite and gypsum in the Gobi desert study case of Kremer et al. (2012). If the microsphere is bacterial in origin, it may be a useful taphonomic indicator of terrestrial exposure within a transitional environment of land and water.

Synthesis of porous iron oxide microspheres by a double hydrophilic block copolymer

Porous microspheres of iron oxide (Fe2O3) are synthesized using a double hydrophilic block copolymer of poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA). The PAA block with negative charge strongly interacts with ferric ions. The assembly of primary nanoparticles at elevated temperature forms the porous microsphere of Fe2O3. The MTT assay of the microspheres based on HepG2 cell indicates good biocompatibility. The thorough porosity of microspheres can accommodate a large amount of anticancer drug cisplatin.

A Facile Synthesis of Multifunctional Iron Oxide@Ag Core–Shell Nanoparticles and Their Catalytic Applications

AbstractA facile approach for the synthesis of iron oxide@Ag core–shell nanoparticles in which iron oxide microspheres serve as the core and the shell consists of silver nanoparticles has been reported. Thermal decomposition of silver acetate at 200 °C in the presence of iron oxide microspheres in diphenyl ether leads to the formation of iron oxide@Ag core–shell nanoparticles. The core–shell nanoparticles were characterized using powder X‐ray diffraction, diffuse reflectance spectroscopy, field emission scanning electron microscopy coupled with energy‐dispersive X‐ray analysis, transmission electron microscopy, and magnetic measurements. The catalytic activity of iron oxide@Ag core–shell nanoparticles has been demonstrated by using two reactions, namely, reduction of 4‐nitrophenol and reduction of methylene blue in aqueous solution.

A Thermal Decomposition Approach for the Synthesis of Iron Oxide Microspheres

ABSTRACTIron oxide microspheres possess a wide range of applications in lithium storage batteries, sensors, photocatalysis, environmental remediation, magnetic resonance imaging and drug delivery. The most commonly used method for the preparation of iron oxide microspheres is hydrothermal synthesis. Besides this, other synthetic methods such as co-precipitation, electrostatic self- assembly, microwave and sol-gel have been reported. The reported synthetic methods usually require longer time (2 to 48 hours) and expensive experimental set up. In the present study, a novel low temperature thermal decomposition approach for the synthesis of iron oxide microspheres has been reported. Thermal decomposition of an iron-urea complex ([Fe(CON2H4)6](NO3)3) in a mixture of diphenyl ether and dimethyl formamide at 200 °C for 35 minutes leads to the formation of iron oxide microspheres. The microspheres were characterized using a variety of analytical techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and magnetometry. The XRD results indicated amorphous nature for the as prepared iron oxide, whereas after calcination at 500 °C, crystalline α-Fe2O3 phase is obtained. The SEM images indicated uniform spheres with an average diameter of 1.2 ± 0.3 μm. The DRS results too gave evidence for the formation of α-Fe2O3 on calcination of the microspheres at 500 oC.The field and temperature dependent magnetic measurement results indicated superparamagnetic behavior for the as prepared iron oxide microspheres indicating that the microspheres consist of iron oxide nanoparticles. On the other hand, an antiferromagnetic behavior was observed for the microspheres calcined at 500 °C. The present synthetic method is a novel method to produce magnetic materials with controlled morphologies.

Formulation and evaluation of drug-loaded targeted magnetic microspheres for cancer therapy

Enhanced and targeted drug delivery using biodegradable microspheres is emerging as a promising approach for cancer therapy. The main objective of the present research was to formulate, characterize, and evaluate iron oxide (magnetic) containing a bovine serum albumin-based microsphere drug delivery system, capable of efficiently delivering sulforaphane, a histone deacetylase inhibitor, for an extended period of time in vivo. Magnetic microspheres were prepared by spray-drying and characterized for their physicochemical properties and dissolution profile. Further, they were evaluated for therapeutic efficacy in in vitro and in vivo systems. In vitro studies in B16 melanoma cells revealed that there was about 13%–16% more inhibition of cell viability when either 30 μM or 50 μM of sulforaphane was used with iron oxide in the polymeric carrier. Data from in vivo studies in C57BL/6 mice revealed that the magnetic microspheres (localized to the tumor site with the help of a strong magnet) inhibited 18% more tumor growth as compared with sulforaphane in solution. In addition, there was a 40% reduction in histone deacetylation levels in mice treated with iron oxide microspheres containing sulforaphane. Thus, magnetic microspheres are shown to be an effective drug delivery system for anticancer drugs.

Cationic poly(lactic-co-glycolic acid) iron oxide microspheres for nucleic acid detection

Herein, we envisage the possibility of preparing stable cationic poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating the iron oxide nanoparticles (IONPs; 8-12 nm). The IONPs are incorporated into PLGA in organic phase followed by microsphere formation and chitosan coating in aqueous medium via nano-emulsion technique. The average size of the microspheres, as determined by dynamic light scattering are about 310 nm, while the zeta potential for the composite remains near 35 mV at pH 4.0. These microspheres are electrophoretically deposited onto indium tin oxide (ITO)-coated glass substrate used as cathode and parallel platinum plate as the counter electrode. This platform is utilized to fabricate a DNA biosensor, by immobilizing a probe sequence specific to Escherichia coli. The bioelectrode shows a surface-controlled electrode reaction with the electron transfer coefficient (α) of 0.64 and charge transfer rate constant (k(s)) of 61.73 s(-1). Under the optimal conditions, this biosensor shows a detection limit of 8.7 × 10(-14) M and is found to retain about 81% of the initial activity after 9 cycles of use.

Adsorption of o-nitrophenol onto nano iron oxide and alginate microspheres: Batch and column studies

In the present study, the adsorption behavior of o-nitrophenol from aqueous medium, using nano iron oxide loaded calcium alginate beads were studied using equilibrium batch and column flow techniques. The effect of pH, adsorbent dose, contact time and temperature on adsorption capacity of the magnetic beads was investigated. The optimum pH value was defined to be 2 at temperature 30°C. The equilibrium data were fitted to Langmuir and Freundlich isotherm models. Batch adsorption data was better described by Freundlich isotherm model than Langmuir model. In column experiments the effect of the initial concentration, bed height and flow rate on o- nitrophenol adsorption were studied. The bed depth service time (BDST) model was used to analyze the experimental data. The sorption capacity per unit bed volume (N0) and rate constant (Ka) were calculated to be 578.4 mg/L and 1.18 L/mg/min, respectively. The characterization of the prepared magnetic beads has been accomplished by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. Key words: Adsorption isotherm, magnetic beads, o- nitrophenol.