Monodisperse Fe3O4 Nanoparticles Research Articles

Versatile electrode platform for determination of hydrogen peroxide in serum samples based on hemoglobin embedded in iron oxide/reduced graphene oxide nanocomposite

Hydrogen peroxide (H2O2) is a vital messenger molecule facilitating signal transmission within cellular systems. The accurate quantification of H2O2 in complex environments, such as human serum, is instrumental in elucidating its diverse biological functions. In this study, we present the development of a robust electrode platform by integrating hemoglobin onto iron oxide (Fe3O4) nanoparticles and reduced graphene oxide (rGO) as a conducting support for the sensitive detection of H2O2 in human serum. The Fe3O4/rGO nanocomposite was synthesized via a facile single-step thermolysis reaction in the presence of oleylamine. Transmission electron microscopy (TEM) analysis revealed the formation of highly monodisperse Fe3O4 nanoparticles that were uniformly dispersed over the reduced graphene surface. The rGO surface provided abundant active sites (Fe3O4) for H2O2 sensing. Consequently, the resulting Hb/Fe3O4@rGO modified electrode exhibited a wide linear range of H2O2 concentrations from 1.5 to 2684 µM, demonstrating high sensitivity and low detection limit. Further characterization of the Hb/Fe3O4@rGO/GC electrode revealed a high surface coverage (τ = 3.0 × 10−9 mol cm−2), charge transfer coefficient (α = 0.83), and electron transfer rate constant (ks = 1.33 s−1). Subsequently, the Hb/Fe3O4@rGO/GC sensor probe was employed to analyze H2O2 in real human serum samples, demonstrating excellent recovery rates ranging from 99.8 % to 104.0 %. The nanocomposite material, designed through the innovative combination of graphene oxide reduction, Fe3O4 nanoparticle decoration, and oleylamine amide/amine bonding, serves as an excellent electrode material for H2O2 concentration sensing. Thus, this study presents a promising platform for the future determination of H2O2 biomarkers in clinical settings.

Viscosity Variations and Tribological Performances of Oleylamine-Modified Fe3O4 Nanoparticles as Mineral Oil Additives

In order to improve the flowabilities and anti-friction and anti-wear properties of lubricants, the viscosity variations and tribological performances of oleylamine-modified Fe3O4 nanoparticles as mineral oil additives were systematically investigated via rotational parallel plate rheometer, ball–disc reciprocating tribometer, non-contact three-dimensional surface profiler, scanning electron microscope, energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy. Spherical monodisperse Fe3O4 nanoparticles were synthesized and dispersed into mineral oils to obtain lubricants with mass fractions of 1%, 3%, 5%, 8%, 10% and 20%, respectively. These lubricants have excellent stabilities within 12 months. Interestingly, the dynamic viscosity and kinematic viscosity of the lubricants first decrease and then increase with the increase in Fe3O4 content, and the lubricants’ viscosity is at a minimum when the mass concentration is 5%. The tensile curves also show that with the mass fraction increase, the lubricants’ tackiness and adhesion have the same change law, and both reach the lowest point when the mass concentration is 5%. Meanwhile, Fe3O4 nanoparticles can improve the tribological properties of the base oils. It is worth noting that the maximum reduction in the wear volume at 25 °C is up to 93.8% compared with base oils when the additive concentration of the Fe3O4 nanoparticles is 5 wt%.

Tumor Microenvironment-Responsive Magnetic Nanofluid for Enhanced Tumor MRI and Tumor multi-treatments.

We prepared a tumor microenvironment-responsive magnetic nanofluid (MNF) for improving tumor targeting, imaging and treatment simultaneously. For this purpose, we synthesized sulfonamide-based amphiphilic copolymers with a suitable pKa at 7.0; then, we utilized them to prepare the tumor microenvironment-responsive MNF by self-assembly of the sulfonamide-based amphiphilic copolymers and hydrophobic monodispersed Fe3O4 nanoparticles at approximately 8 nm. After a series of characterizations, the MNF showed excellent application potential due to the fact of its high stability under physiological conditions and its hypersensitivity toward tumor stroma by forming aggregations within neutral or weak acidic environments. Due to the fact of its tumor microenvironment-responsiveness, the MNF showed great potential for accumulation in tumors, which could enhance MNF-mediated magnetic resonance imaging (MRI), magnetic hyperthermia (MH) and Fenton reaction (FR) in tumor. Moreover, in vitro cell experiment did not only show high biocompatibility of tumor microenvironment-responsive MNF in physiological environment, but also exhibit high efficacy on inhibiting cell proliferation by MH-dependent chemodynamic therapy (CDT), because CDT was triggered and promoted efficiently by MH with increasing strength of alternating magnetic field. Although the current research is limited to in vitro study, these positive results still suggest the great potential of the MNF on effective targeting, diagnosis, and therapy of tumor.

Magnetoresponsive Artificial Cilia Self-Assembled with Magnetic Micro/Nanoparticles.

Biological cilia have exquisitely organized dynamic ultrafine structures with submicron diameters and exceptional aspect ratios, which are self-assembled with ciliary proteins. However, the construction of artificial cilia with size and dynamic functions comparable to biological cilia remains highly challenging. Here, we propose a self-assembly technique that generates magnetoresponsive artificial cilia with a highly ordered 3D structural arrangement using vapor-phase magnetic particles of varying sizes and shapes. We demonstrate that both monodispersed Fe3O4 nanoparticles and Fe microparticles can be assembled layer-by-layer vertically in patterned magnetic fields, generating both "nanoscale" or "microscale" artificial cilia, respectively. The resulting cilia display several structural features, such as diameters of single particle resolution, controllable diameters and lengths spanning from nanometers to micrometers, and accurate positioning. We further demonstrate that both the magnetic nanocilia and microcilia can dynamically and immediately actuate in response to modulated magnetic fields while providing different stroke ranges and actuation torques. Our strategy provides new possibilities for constructing artificial nano- and microcilia with controlled 3D morphology and dynamic field responsiveness using magnetic particles of varied sizes and shapes.

SYNTHESIS AND STUDY OF STRUCTURES OF MAGNETITE Fe3O4 NANOPARTICLES IN POLYETHYLENE GLYCOL MEDIUM

Synthesis of magnetite Fe3O4 nanoparticles functionalized with polyethylene glycol was carried out by co-precipitation method using a very small amount of organic substances to obtain a highly monodisperse form of nanoparticles, and the structure of obtained Fe3O4 nanoparticles was studied by physical methods. During the synthesis of magnetic Fe3O4 nanoparticles surrounded by a polymer, it has been determined that by adjusting the amount of used polymer, the nature of the precipitating agent, the concentration of the initial precursors and the temperature it was possible to synthesize and stabilize monodisperse Fe3O4 nanoparticles with a high degree of purity, uniform in size

Superparamagnetic Iron Oxide Nanoparticles (SPIONs) and Reduced Graphene Oxide (RGO) Based Nanocomposites Prepared by Low-Temperature Route and Their Anticancer Properties

In this work, a facile low temperature solution route was reported for the preparation of monodisperse Fe3O4 nanoparticles and their reduced graphene oxide (RGO) based nanocomposites and used as anticancer agents. X-ray diffraction spectroscopy XRD and Raman studies revealed the high crystalline nature of the Fe3O4 nanoparticles and the presence of characteristic peaks of RGO in Fe3O4/RGO nanocomposites. Transmission electron microscopy (TEM) micrographs showed the morphology of the RGO nanosheets decorated by Fe3O4 nanoparticles with sizes ranging from 10–15 nm. High resolution (HR)-TEM study revealed the formation of Fe3O4/RGO nanocomposites with the interplanar spacing corresponding to the (311) plane of Fe3O4. The anti-cancer properties of Fe3O4/RGO nanocomposites against A549 cells were investigated using MTT, NRU assay, morphology of cells, and ROS generation analyses and compared with the pure Fe3O4 nanoparticles. In comparison between both the pure Fe3O4 and Fe3O4/RGO nanocomposites, more damage to the A549 cells resulted from the nanocomposites at a similar concentration of 100 μg/ml. The cell viability test showed that 36% cell viability was observed at a concentration of 100 μg/ml for Fe3O4/RGO nanocomposites. Additionally, the percentage of ROS generation for Fe3O4/RGO nanocomposites was higher than that of Fe3O4 at a concentration of 100 μg/ml. These results suggested that the as-synthesized nanocomposites might be a potential candidate for future anticancer agents.

Slow oxidation of magnetite nanoparticles elucidates the limits of the Verwey transition

Magnetite (Fe3O4) is of fundamental importance for the Verwey transition near TV = 125 K, below which a complex lattice distortion and electron orders occur. The Verwey transition is suppressed by chemical doping effects giving rise to well-documented first and second-order regimes, but the origin of the order change is unclear. Here, we show that slow oxidation of monodisperse Fe3O4 nanoparticles leads to an intriguing variation of the Verwey transition: an initial drop of TV to a minimum at 70 K after 75 days and a followed recovery to 95 K after 160 days. A physical model based on both doping and doping-gradient effects accounts quantitatively for this evolution between inhomogeneous to homogeneous doping regimes. This work demonstrates that slow oxidation of nanoparticles can give exquisite control and separation of homogeneous and inhomogeneous doping effects on the Verwey transition and offers opportunities for similar insights into complex electronic and magnetic phase transitions in other materials.

Water-Dispersible Fe3O4 Nanoparticles Modified with Controlled Numbers of Carboxyl Moieties for Magnetic Induction Heating

Monodisperse Fe3O4 nanoparticles (NPs) with excellent water dispersibility and stability were prepared by the introduction of the carboxyl group (−COOH) on the surface of the as-prepared oleyl-capped Fe3O4 NPs. Controlled introduction of the COOH moieties on the NP surface was carried out by a simple ligand exchange reaction using two types of phosphonic acid ligands with dodecyl moiety and the terminal COOH group. The degree of modification of the COOH group on the particle surface was controlled by tuning the molar ratios of the two phosphonic acids. During the ligand exchange reaction, no change was observed in the crystal structure and morphology of the Fe3O4 NPs. The results of Fourier transform infrared (FT-IR) spectroscopy confirmed that the two ligands were bound to the Fe3O4 NP surface through their phosphoric acid functional groups. The surface coverage and molar ratios of the two ligands were evaluated by thermal gravimetric analysis (TGA) and via proton nuclear magnetic resonance (1H NMR) measurements, respectively. Results obtained from the thermal analyses were consistent with the initial molar ratios of the ligands used in the reaction, which reflect on the efficiency of the developed ligand exchange process. Our COOH-modified Fe3O4 NPs could be dispersed in water by deprotonation for over 6 months and exhibit a typical ferrofluid behavior without the addition of other surfactants and dispersants, showing high dispersion stability. Furthermore, the magnetic induction heating performance of the Fe3O4 NPs in aqueous dispersions was evaluated and the specific absorption rate (SAR) value was estimated to be 38.3 W/g Fe. These results suggest that our COOH-modified Fe3O4 NPs with the desired number of COOH surface moieties can be advantageous for applications such as precise surface design, water-based ferrofluid, and hyperthermia treatment.

4-in-1 Fe3O4/g-C3N4@PPy-DOX nanocomposites: Magnetic targeting guided trimode combinatorial chemotherapy/PDT/PTT for cancer

At present, cancer has become a major disease threatening human health worldwide. Therefore, developing targeting guided multimode synergetic therapy has become one of the hot spots in current antitumor research and is also a great challenge. Herein, a new Fe3O4/g-C3N4@PPy-DOX nanocomposite containing magnetic iron oxide (Fe3O4) nanoparticles (NPs), lamellar structure of graphite-like carbon nitride (g-C3N4) and polypyrrole (PPy) shell with the loaded anti-tumor drug doxorubicin hydrochloride (DOX) was designed and prepared. The monodisperse Fe3O4 nanoparticles (NPs) with the diameter of 20 nm endowed the nanocomposite with the magnetic targeting ability, reducing damage to normal tissues. It is very interesting that the Fe3O4 NPs also possessed photosensitizer function for photodynamic therapy (PDT). The g-C3N4 sheets as the photocatalysis towards the degradation of water for generating O2 could effectively improve the hypoxia of solid tumors and increase the efficiency of PDT. In addition, PPy has high light-to-heat conversion efficiency, so was chosen for the cancer photothermal therapy (PTT). Finally, an anticancer drug (DOX) was loaded on the nanocomposite because the presence of mesoporous structure. Thus, the prepared Fe3O4/g-C3N4@PPy-DOX nanocomposites exhibit synergetic chemotherapy/PTT/enhanced PDT antitumor effect. This study provides an inspiration for combining targeting and multimodality to improve the anticancer efficiency.

Controllable synthesis of monodispersed iron oxide nanoparticles by an oxidation-precipitation combined with solvothermal process

As an important magnetic inorganic nanomaterial, iron oxide nanoparticles have exceptionally outstanding physical and chemical properties for bio-medicine and chemistry applications. Traditional Fe3O4 nanopowders normally have heavy aggregation problems, which may limit their applications. In this study, we made monodispersed Fe3O4 nanoparticles with an average size of 5–12 nm using a combination of oxidation-precipitation with solvothermal method. The Fe2+ in the reaction system can be partially oxidized to Fe3+ by the ambient air as an oxidizing agent, therefore, the precipitation process does not require nitrogen and other oxidants or reductants. The monodispersed Fe3O4 nanoparticles can be successfully modified and steadily dispersed in cyclohexane or n-hexane. The effects of different types of surfactants and alcohols, addition amount of surfactants and alkali, and ratio of ethanol-water solution were explored to obtain the optimum synthesis conditions. In addition, the different phase composition and morphology of final product can be simply adjusted using different addition amount of alkali to get Fe3O4, α-Fe2O3, γ-Fe2O3 and α-FeOOH nanoparticles. We believe that the monodispersed Fe3O4 nanoparticles with a good dispersibility and magnetic response may have great application prospects in biological medicine, chemocatalysis and magnetic recording for future research.

High-throughput screening of bisphenols using magnetic covalent organic frameworks as a SELDI-TOF-MS probe.

Core-shell structured magnetic covalent organic framework (Fe3O4@COF) nanospheres were rapidly synthesized at room temperature using the monodisperse Fe3O4 nanoparticles (NPs) as magnetic core and benzene-1,3,5-tricarbaldehyde (BTA) and 3,3'-dihydroxybenzidine (DHBD) as two building blocks (denoted as Fe3O4@BTA-DHBD), respectively. They can serve as a mass spectrometry probe for rapid and high-throughput screening of bisphenols (BPs) from pharmaceuticals and personal care products (PPCPs) by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). The Fe3O4@BTA-DHBD nanospheres showed some superior features involving average pore size distribution (2.82nm), high magnetization values (42.5emug-1), high specific surface area (82.96m2g-1), and good chemical/thermal stability. It was used as both ideal adsorbent for enrichment of BPs and new substrate to assist ionization in SELDI-TOF-MS. The method exhibited good linearity in the range 0.05-4000ngmL-1 with correlation coefficients (r) higher than 0.9920. Lowlimits of detection (LODs) (500pgmL-1 for bisphenol A (BPA), 2pgmL-1 for bisphenol B (BPB), 28pgmL-1 for bisphenol C (BPC), 60pgmL-1 for bisphenol F (BPF), 33pgmL-1 for bisphenol AF (BPAF), 200pgmL-1 for bisphenol BP (BPBP), 10pgmL-1 for bisphenol S (BPS), 90pgmL-1 for tetrabromobisphenol A (BPA(Br)4), and 380pgmL-1 for tetrabromobisphenol S (BPS(Br)4)) and good recoveries (80.6-115%) of BPs in PPCPs were achieved. The relative standard deviations (RSDs) of spot-to-spot (n = 10) and sample-to-sample (n = 5) were in the ranges 5-11% and 5-12%, respectively. The dual-function platform was successfully applied to the quantitative determination of BPs in PPCPs. It not only expanded the scope of the application of COFs but also provided an alternative strategy for the determination of hazardous compounds in PPCPs. Graphical abstract Schematic representation of the synthesis of core-shell structured magnetic covalent organic framework nanospheres (Fe3O4@COFs) and its application in the analysis of bisphenols by using Fe3O4@BTA-DHBD nanospheres as a MS probe based on surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

The first material made for air pollution control able to sequestrate fine and ultrafine air particulate matter

Air pollution accounts as a critical environmental issue in different populated cities. With the introduction of smart cities concept, suitable measures to reduce people exposition to pollutants must be part of the policies for a suitable urban development. Generally urban policy makers have proposed some restrictions (for example for traffic), that were resulted insufficient. Then probably, different approaches may be considered to face the air pollution problem.This paper proposes a new porous hybrid material (SUNSPACE) based on the use of industrial silicate minerals and alginate materials to promote PM sequestration in urban areas. It was designed to be applied as a coating on all available external cities surfaces. The synthesis conditions were slightly modified, with respect to the original material, to avoid thermal treatment, and make the material directly applicable. SUNSPACE was characterized by using different techniques: nitrogen physisorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results identify the presence of ink-bottle pores shape, suitable to sequestrate nano and micro PM.Moreover, PM reduction in the atmosphere generally occurs as a consequence of wet or dry deposition conditions, monodisperse Fe3O4 nanoparticles and indoor/outdoor exposure were used to investigate the ability of SUNSPACE in ultrafine PM sequestration.

Antibacterial Silver-Conjugated Magnetic Nanoparticles: Design, Synthesis and Bactericidal Effect.

The aim was to design and thoroughly characterize monodisperse Fe3O4@SiO2-Ag nanoparticles with strong antibacterial properties, which makes them a candidate for targeting bacterial infections. The monodisperse Fe3O4 nanoparticles were prepared by oleic acid-stabilized thermal decomposition of Fe(III) oleate; the particles were coated with silica shell using a water-in-oil reverse microemulsion, involving hydrolysis and condensation of tetramethyl orthosilicate. Resulting Fe3O4@SiO2 particles were modified by (3-mercaptopropyl)trimethoxysilane to introduce 1.1mmol SH/g. Finally, the Fe3O4@SiO2-SH nanoparticles were decorated with silver nanoclusters formed by reduction of silver nitrate with NaBH4. The particles were analyzed by FTIR, X-ray photoelectron and atomic absorption spectroscopy, dynamic light scattering and vibrating sample magnetometry. The antibacterial activity of the Fe3O4@SiO2 and Fe3O4@SiO2-Ag nanoparticles was tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria cultivated on Luria agar plates or in Luria broth. The superparamagnetic Fe3O4@SiO2-Ag nanoparticles (21nm in diameter; saturation magnetization 26 A∙m2/kg) were successfully obtained and characterized. Inhibitory and toxic effects against bacteria were documented by incubation of the Fe3O4@SiO2-Ag nanoparticles with Staphylococcus aureus and Escherichia coli. The combination of magnetic properties together with bactericidal effects is suitable for the disinfection of medical instruments, water purification, food packaging, etc.

An efficient approach for the synthesis of magnetic separable Fe3O4@TiO2 core-shell nanocomposites and its magnetic and photocatalytic performances

A convenient and efficient approach for the synthesis of Fe3O4@TiO2 nanocomposites with core-shell structure has been demonstrated. It takes four steps for synthesis process. Oleic acid-coated monodisperse Fe3O4 nanoparticles are obtained firstly, and surface modified Fe3O4 nanoparticles are followed to proceed. Then Fe3O4@TiO2 core-shell nanocomposites are subsequently synthesized using tetrabutyl titanate (TBOT) as titanium source and some polar aprotic solvents used as the mixed solvents. The obtained core-shell structure is composed of a central Fe3O4 nanoparticle core with sequential TiO2 surface, whereas the outer TiO2 coating was useful for the degradation of organic contaminants. Different core-shell nanocomposites in different polar solution are obtained. Shell thickness of Fe3O4@TiO2 nanocomposites could be adjusted rationally by changing synthetic conditions. The measurements of the magnetic properties demonstrate that the Fe3O4@TiO2 core-shell nanocomposites exhibit magnetic behavior at room temperature. The degradation of methylene blue solution was also explored.

Monodisperse Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy Core-Shell Composite Nanospheres for IBU Loading and Release.

The magnetic targeting drug delivery system is an effective way of targeting therapy. In this study, the monodisperse Fe3O4 nanoparticles with a particles size of about 180 nm were first prepared via a solvothermal method. Subsequently, the core-shell structure Fe3O4/SiO2 and Fe3O4/SiO2/polypyrrole (PPy) composite nanospheres were successfully synthesized by coating Fe3O4 nanoparticles with SiO2 shell layer using the Stöber method and PPy shell by solvothermal method in turn. The as-prepared nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and Ultraviolet-Visible spectrophotometer (UV-Vis). The results indicated that the as-prepared composite nanospheres displayed a well-defined core-shell structure and monodispersity. The thicknesses of SiO2 shell and PPy shell were ~6 nm and ~19 nm, respectively. Additionally, the as-prepared nanoparticles exhibited high saturation magnetization of 104 emu/g, 77 emu/g, and 24 emu/g, and have great potential applications in drug delivery. The drug loading and drug release of the Fe3O4/SiO2 and Fe3O4/SiO2/PPy composite nanospheres to ibuprofen (IBU) under stirring and ultrasonication were investigated. Their drug loading efficiency and drug release efficiency under ultrasonication were all higher than 33% and 90%, respectively. The drug release analyses showed sustained release of IBU from nanospheres and followed the Korsmeyer-Peppas model.

SYNTHESIS OF MAGNETIC NANOPARTICLES FROM SPENT PICKING LIQUORS IN AQUEOUS SATURATED SOLUTION OF CALCIUM HYDROXIDE

Spent pickling liquor is a considered hazardous waste because of its very high level of acidity and high metal concentration, and the conventional neutralization method regenerates an excessive quantity of sludge that poses a serious problem concerning to the landfill disposal and risk of ground water contamination. Therefore, recovery of spent pickling liquor is necessary. Several approaches have been investigated for spent pickling liquor recovery, but they are generally costly and lead to produce various iron salts or oxides which have a limited value. In the present study, we explore the potential of using spent pickling liquor as iron precursor for the synthesis of magnetic nanoparticles. Here, Fe3O4 nanoparticles were prepared easily by oxidation-precipitation from spent hydrochloride acid pickling liquors in aqueous saturated solution of calcium hydroxide at room temperature, in the air, and under suitable speed of rotation. The FT-IR, XRD and TEM results shown that monodisperse Fe3O4 nanoparticles in the size range of 10-25 nm were obtained, with a high level of crystallinity. The BET surface area was about 46 m2 g-1. The synthesized Fe3O4 nanoparticles exhibited the superparamagnetic behavior with relatively high saturation magnetization, Ms = 73 emu/g. The synthesis procedure of magnetic nanoparticles revealed here will provide a new possibility for spent pickling liquors recovery more effectively.
 For citation:
 Vu Minh X., Le Ha T. T., Pham Lan T., Pham Nam H., Le Huong T. M., Le Lu T. Nguyen Dung T. Synthesis of magnetic nanoparticles from spent picking liquors in aqueous saturated solution of calcium hydroxide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 59-63

Synthesis and characterization of monodispersed water dispersible Fe3O4 nanoparticles and in vitro studies on human breast carcinoma cell line under hyperthermia condition

Monodispersed Fe3O4 magnetic nanoparticles (MNPs) having size of 7 nm have been prepared from iron oleate and made water dispersible by functionalization for biomedical applications. Three different reactions employing thioglycolic acid, aspartic acid and aminophosphonate were performed on oleic acid coated Fe3O4. In order to achieve a control on particle size, the pristine nanoparticles were heated in presence of ferric oleate which led to increase in size from 7 to 11 nm. Reaction parameters such as rate of heating, reaction temperature and duration of heating have been studied. Shape of particles was found to change from spherical to cuboid. The cuboid shape in turn enhances magneto-crystalline anisotropy (Ku). Heating efficacy of these nanoparticles for hyperthermia was also evaluated for different shapes and sizes. We demonstrate heat generation from these MNPs for hyperthermia application under alternating current (AC) magnetic field and optimized heating efficiency by controlling morphology of particles. We have also studied intra-cellular uptake and localization of nanoparticles and cytotoxicity under AC magnetic field in human breast carcinoma cell line.

Preparation and Application of Magnetically Recoverable Cationic Exchanger Support on Monodisperse Fe3O4 Nanoparticles

A magnetically recoverable cationic exchanger has been effectively prepared through immobilized chloroacetic acid (CA) onto the Fe3O4 nanoparticles. The magnetic nanoparticles (MNPs) were synthesized by a coprecipitation method in an aqueous system. The MNPs were modified with sodium silicate and chloroacetic acid (CA), thus endowed these nanoparticles with strong magnetism and good dispersion. The physicochemical properties of the cationic exchange materials were characterized with Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The magnetic properties of the cationic exchange materials were analyzed by a vibrating sample magnetometer (VSM). The content of ions was measured by atomic absorption spectrophotometric method. The prepared cationic exchange nanoparticles display an excellent magnetic property with a saturation magnetization value of 26.58 emu/g and the prepared exchanger possess considerable thermal stability, which indicating a great potential application in heavy metal ion wastewater treatment. In this experiment, the exchange capacity of lead ion was 3.4 mmol g–1, And the maximum lead removal rate is up to 73.85%.

Facile synthesis of magnetic covalent organic framework nanobeads and application to magnetic solid-phase extraction of trace estrogens from human urine

A rapid and facile approach was developed for the synthesis of core-shell structured magnetic covalent organic framework nanobeads by using the monodisperse Fe3O4 nanoparticles (NPs) as magnetic core, and 1,3,5-triformylbenzene (Tb) and benzidine (Bd) as two building blocks (denoted as Fe3O4@TbBd), which were explored as an adsorbent for magnetic solid-phase extraction (MSPE) of estrogens from human urine sample. The core-shell structured Fe3O4@TbBd nanobeads showed some attractive features involving high specific surface area (202.18 m2/g), uniform pore size distribution (2.8 nm), high magnetic responsivity (41.4 emu/g), as well as excellent thermal and chemical stability, which made it an ideal adsorbent for selective isolation and enrichment of estrogens. Some parameters influencing extraction efficiency, including adsorbent dosage, extraction time, pH, ion strength, desorption solvent and desorption time were investigated systematically. Combined with HPLC–MS, a simple, fast, and sensitive method was developed for the enrichment and sensitive determination of seven estrogens, which showed good linearity (r > 0.9978) in the range of 0.005–10 μg/L, low limits of detection (0.2–7.7 ng/L, S/N = 3), low limits of quantification (0.6–25.6 ng/L, S/N = 10), high enrichment factors (75–197 fold), and good precision with relative standard deviations (RSD) lower than 4.8% for intra-day and 6.7% for inter-day. The proposed method was successfully applied to the analysis of trace estrogens in urine sample of pregnant woman with good recoveries (80.6–111.6%), demonstrating the promising potential of the Fe3O4@TbBd nanobeads as adsorbent in sample pretreatment.

Role of silver nanoshells on structural and magnetic behavior of Fe3O4 nanoparticles

The structural and magnetic behavior of monodispersed uncoated Fe3O4 nanoparticles (average particle size = 6 nm) and silver coating of mean thickness 1.5 nm and 2 nm prepared in an emulsion was investigated. The structural and magnetic analysis indicated the formation of a tri layer structure comprising of a disordered magnetic layer of diffused core present in between magnetic core and non-magnetic shell. The nanocrystals with thicker nanoshells exhibit superparamagnetic properties showing decrease in blocking temperatures with increasing shell thickness, whereas the particles of larger diameter are ferrimagnetic at room temperature. The value of saturation magnetization are smaller than those obtained for bulk magnetite emphasizing the presence of a disordered spin layer due to unsaturated iron ions at the surface in case of uncoated magnetite nanoparticles and at the interface for coated ones. The spin canting at the interface, surface strain and increased magnetoelastic anisotropy are some other factors influencing the magnetic properties of these nanoparticles.