Iron Oxide Nanomaterials Research Articles

Structural, dielectric, optical and magnetic studies of dysprosium doped iron oxide nanostructures

Lanthanide-doped iron oxide nanomaterials are potential candidates of current interest for many advanced applications. In this paper, we report on the synthesis of pure and dysprosium (Dy3+) ion doped iron oxide nanostructures, such as ⍺-DyxFe2-xO3 by employing a sol-gel auto combustion method. The pure and doped iron oxide nanostructures have been characterized by employing X-ray diffraction (XRD), transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The synthesized nanostructures were studied for dielectric, optical and magnetic properties. Dy3+ ion doped ⍺-Fe2O3 nanostructures shows enhancement in the dielectric properties as compared to pure ⍺-Fe2O3. Temperature-dependent conductivity follows Motts law, which confirms the mechanism of variable range hopping in them. Band gap and photoluminescence increases with increase in concentration of Dy3+ ion doping in ⍺-Fe2O3 system. Saturation magnetization increases significantly in doped systems. It was observed that doped systems saturate at low fields (10 kOe) as compared to pure ⍺-Fe2O3 system, which does not saturate up to the maximum applied field (20 kOe). High value of saturation magnetization at low applied magnetic fields, large band gap, enhanced dielectric and efficient photoluminescent properties makes the Dy3+ ion doped iron oxide nanostructures possibly the potential candidates for device applications.

Synthesis of highly magnetic iron oxide nanomaterials from waste iron by one-step approach

One of the biggest challenges of present-day scientific research is the disposal and/or recycling of environmental waste. In this work, scrap iron obtained from a blacksmith’s backyard was used as precursor for the synthesis of magnetic nanomaterials. Highly magnetic iron based nanomaterials were synthesized in presence of urea and alkali by carefully tuning the precursor concentration and temperature. Characterization of the synthesized nanomaterials was done by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The magnetic behavior of the synthesized iron-oxide nanoparticles was studied using a squid magnetometer. The net impact of the work reported herein is based on the principle of “Wealth-from-Waste”. Waste scrap iron was converted by a scalable synthetic strategy to useful nanomaterials with potential magnetic applications.

The Influence of Synthesis Parameters on Structural and Magnetic Properties of Iron Oxide Nanomaterials.

Magnetic iron oxides have been used in biomedical applications, such as contrast agents for magnetic resonance imaging, carriers for controlled drug delivery and immunoassays, or magnetic hyperthermia for the past 40 years. Our aim is to investigate the effect of pressure and temperature on the structural, thermal, and magnetic properties of iron oxides prepared by hydrothermal synthesis at temperatures of 100–200 °C and pressures of 20–1000 bar. It has been found that pressure influences the type of iron oxide crystalline phase. Thus, the results obtained by Mössbauer characterization are in excellent agreement with X-ray diffraction and optical microscopy characterization, showing that, for lower pressure values (<100 bar), hematite is formed, while, at pressures >100 bar, the major crystalline phase is goethite. In addition, thermal analysis results are consistent with particle size analysis by X-ray diffraction, confirming the crystallization of the synthesized iron oxides. One order of magnitude higher magnetization has been obtained for sample synthesized at 1000 bar. The same sample provides after annealing treatment, the highest amount of good quality magnetite leading to a magnetization at saturation of 30 emu/g and a coercive field of 1000 Oe at 10 K and 450 Oe at 300 K, convenient for various applications.

Rituximab conjugated iron oxide nanoparticles for targeted imaging and enhanced treatment against CD20-positive lymphoma.

Since its launch in 1997, rituximab (RTX) has extensively improved the treatment of CD20-positive follicular and diffuse large B cell non-Hodgkin lymphoma (NHL). The application of RTX is limited usually by the failed therapy because of resistance. Iron oxide nanomaterials have been explored for cancer detection and treatment in recent years. In this study, a multivalent nanoprobe comprising one Fe3O4 nanoparticle and several RTX antibodies was constructed for the targeted imaging and enhanced treatment of NHL. Poly(ethylene glycol) (PEG)-coated Fe3O4 nanoparticles were fabricated via a thermal decomposition method and ligand exchange. RTX was conjugated onto the surface of the Fe3O4-PEG nanoparticles to form Fe3O4-PEG-nAb (n = 2, 5 or 8) multivalent nanoprobes. These multivalent nanoprobes, with a core size of approximately 11 nm and a hydrodynamic diameter of about 22 nm, showed colloidal stability in buffer solution. The r2 relaxation rate of Fe3O4-PEG-nAb was similar to that of Fe3O4-PEG (309 ± 3.08 mM-1 s-1). The specificity of nanoprobes for CD20-positive Raji cells was assessed on a clinical magnetic resonance imaging scanner. The receptor binding site of one multivalent nanoprobe was more than that of one RTX, exhibiting valence-dependent induction of Raji cell apoptosis, and this effect could be enhanced by complement activation from blood serum added. A similar activity was observed in vivo in a NHL xenograft model. The multivalent nanoprobe treatment significantly reduced tumor burden and enhanced survival in comparison to the RTX group. Our studies demonstrate that the appropriate design and preparation of anticancer antibody-nanoparticle conjugates enable the generation of improved anticancer nanomedicines and could thus provide an efficient cancer theranostic strategy.

Autophagy Modulated by Inorganic Nanomaterials.

With the rapid development of nanotechnology, inorganic nanomaterials (NMs) have been widely applied in modern society. As human exposure to inorganic NMs is inevitable, comprehensive assessment of the safety of inorganic NMs is required. It is well known that autophagy plays dual roles in cell survival and cell death. Moreover, inorganic NMs have been proven to induce autophagy perturbation in cells. Therefore, an in-depth understanding of inorganic NMs-modulated autophagy is required for the safety assessment of inorganic NMs. This review presents an overview of a set of inorganic NMs, consisting of iron oxide NMs, silver NMs, gold NMs, carbon-based NMs, silica NMs, quantum dots, rare earth oxide NMs, zinc oxide NMs, alumina NMs, and titanium dioxide NMs, as well as how each modulates autophagy. This review emphasizes the potential mechanisms underlying NMs-induced autophagy perturbation, as well as the role of autophagy perturbation in cell fate determination. Furthermore, we also briefly review the potential roles of inorganic NMs-modulated autophagy in diagnosis and treatment of disease.

Synthesis of Green Recyclable Magnetic Iron Oxide Nanomaterials Coated by Hydrophobic Plant Extracts for Efficient Collection of Oil Spills

A facile method for synthesis of environmentally friendly magnetite nanomaterials (MNMs) was applied using hydrophobic biocomponents as capping and stabilizing agents. The biocomponents were extracted from Matricaria aurea (MAE) and Ochradenus baccatus (OBE) and used for the surface modification of MNMs to increase their dispersion efficiency on the collection of heavy crude oil spills. Synthesized MNM samples (MAE-MNMs and OBE-MNMs) were verified using thermogravimetric analysis; Fourier-transform infrared spectroscopy; transmission electron microscopy; dynamic light scattering, and vibrating-sample magnetometry. The application of these nanomaterials in the collection of oil spill showed that the MAE-MNMs and OBE-MNMs successfully collected 95% and 91% of the oil spill, respectively. These results support the potential use of these materials as eco-friendly composites for the successful collection of oil spills that might occur during offshore operations.

Silica Removal Using Magnetic Iron-Aluminum Hybrid Nanomaterials: Measurements, Adsorption Mechanisms, and Implications for Silica Scaling in Reverse Osmosis.

Composite magnetic aluminum hydroxide at iron oxide nanomaterials, Al(OH)3@Fe3O4, with a well-defined core-shell structure, were used as pretreatment adsorbents for the removal of silica in brackish water. The Al(OH)3 outer shell confers silica adsorption capacity, and the superparamagnetic Fe3O4 core allows material separation and magnetic recovery. The as-prepared nanomaterials (2 g L-1) remove ∼95 and ∼80% silica from Si-rich solutions with 0.5 and 2 mM initial silica concentrations, respectively. Regeneration under basic conditions was evaluated, and post-adsorption treatment with 0.05 M NaOH yielded optimal material reusability. After four regeneration cycles, the Al(OH)3@Fe3O4 nanomaterials retain their magnetic property while still being able to remove ∼40% silica from solutions at an adsorbent concentration of 2 g L-1. The mechanism of silica adsorption onto the surface of the nanomaterials was probed using several spectroscopic techniques. ATR-FTIR (attenuated total reflection-Fourier transform infrared) integrated with two-dimensional correlation analysis shows that silica species vary from Q2 to Q4 with adsorption time corresponding to silica polymerization. 29Si solid-state NMR spectra show an upfield chemical shift displacement of the Q2 signal, which indicates the formation of Q4 units, suggesting silica polymerization onto the Al(OH)3 shell. In addition, a laboratory-scale reverse osmosis setup was used to evaluate Al(OH)3@Fe3O4 as pretreatment materials for silica removal. Results show that silica scaling was significantly alleviated, and water recovery was enhanced when feed waters were pretreated with the magnetic nanomaterials. Taken together, our study highlights the promise of magnetic Al(OH)3@Fe3O4 nanomaterials in treating brackish water and achieving higher water recovery for inland desalination.

Evolution of gluconic acid capped paramagnetic iron oxide nanoparticles

Magnetic iron oxide nanomaterials are essential for many industrial, environmental and biomedical applications. While ferromagnetic and superparamagnetic iron oxide materials are known, paramagnetic iron oxide nanoparticles have not been significantly reported. In this study, we report the synthesis and characterization of the gluconic acid capped paramagnetic iron oxide nanoparticles (PIONs) using a simple green co-precipitation approach. The PIONs were characterized using Fourier Transform infrared spectroscopy, Scanning electron microscopy, X-ray diffractiometry, differential scanning calorimetry, thermogravimetry, Brunauer–Emmett–Teller (BET) and vibrating sample magnetometry (VSM). The material exhibited linear relationship between magnetization and the field, thus confirming its paramagnetic nature. Also, the as-synthesized PIONs showed a positive zeta potential (+29.7 mV), H2 type IV mesoporous characteristics (pore size = 3.09 nm) with a higher surface area (261.31 m2/g) than some materials in the literature. The as-synthesized material, exhibited potentials for catalysis, organic synthesis, adsorption, environmental remediation and magnetic resonance T1 bio-imaging.

Cerium- and Iron-Oxide-Based Nanozymes in Tissue Engineering and Regenerative Medicine

Nanoparticulate materials displaying enzyme-like properties, so-called nanozymes, are explored as substitutes for natural enzymes in several industrial, energy-related, and biomedical applications. Outstanding high stability, enhanced catalytic activities, low cost, and availability at industrial scale are some of the fascinating features of nanozymes. Furthermore, nanozymes can also be equipped with the unique attributes of nanomaterials such as magnetic or optical properties. Due to the impressive development of nanozymes during the last decade, their potential in the context of tissue engineering and regenerative medicine also started to be explored. To highlight the progress, in this review, we discuss the two most representative nanozymes, namely, cerium- and iron-oxide nanomaterials, since they are the most widely studied. Special focus is placed on their applications ranging from cardioprotection to therapeutic angiogenesis, bone tissue engineering, and wound healing. Finally, current challenges and future directions are discussed.

Controllable Design of Polypyrrole-Iron Oxide Nanocoral Architectures for Supercapacitors with Ultrahigh Cycling Stability

Polypyrrole-modified iron oxide nanomaterials have been synthesized employing a one-step hydrothermal protocol. The influence of the reaction temperature has been investigated by performing the synthesis at four different temperatures (Ppy@Fe2O3-120 °C, Ppy@Fe2O3-140 °C, Ppy@Fe2O3-160 °C, and Ppy@Fe2O3-180 °C). Synthesized materials exhibited an unprecedentedly peculiar morphology (star/coral reef-like architectures), induced by the presence of pyrrole in the reaction media. Full characterization of the samples revealed the critical influence of temperature on the crystallinity, textural properties and specially on (C+N)/Fe surface ratios in the materials. As-synthesized nanohybrids were integrated into electrodes to construct supercapacitor devices. A effective tuning of the electrochemical features was achieved by controlling the (C+N)/Fe ratio on the surface, strongly dependent on reaction temperature. The best electrochemical performance was reached by Ppy@Fe2O3-180 °C nanohybrid, which exhibited a re...

In vitro inhibition of tumor growth by low-dose iron oxide nanoparticles activating macrophages.

Macrophages as immunocyte are attracting more and more attention in cancer therapy. Our previous study observed that dimercaptosuccinic acid (DMSA)-coated Fe3O4 magnetic nanoparticles triggered comprehensive immune responses of mouse macrophages (RAW264.7 cells) and induced production of many kinds of cytokines. This study investigated the effects of Fe3O4 magnetic nanoparticles on RAW264.7 cells proliferation, migration, and inhibition of tumor growth in vitro. Fe3O4 magnetic nanoparticles had an average size of about 11 nm with good dispersibility and uniformity. Fe3O4 magnetic nanoparticles internalized efficiently into RAW264.7 cells. Through Cell Counting Kit-8 (CCK-8) detection, the proliferation of RAW264.7 cells significantly increased by the low-dose Fe3O4 magnetic nanoparticles (50 µg/mL) treatment. The results of wound-healing and Transwell assays both displayed a significant promotion of the RAW264.7 cells migratory capability compared with control group ( P<0.01). It is interesting to find that a large number of proliferated RAW264.7 cells were activated to surround quickly and attack mouse liver cancer cell (Hepa1-6) cells by Fe3O4 magnetic nanoparticles. The growth of Hepa1-6 cells was effectively inhibited according to microscope imaging and flow cytometry analysis. The inhibition may be cooperative effects of RAW264.7 cells proliferation, migration, and immune activation. The results suggest potential clinical value of low-dose iron oxide nanomaterials in cancer therapy.

Enhanced removal of lead ions from aqueous solution by iron oxide nanomaterials with cobalt and nickel doping

Wastewater containing heavy metal ions such as lead should be treated for cleanup before discharge to environment. This work reports new nanomaterials of orthohexagonal iron oxide for efficient removal of lead (II), which were doped with cobalt (CoFe2O3) or Nickel (NiFe2O3) ions through a simple method. The structure of adsorbents and adsorption mechanism were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometer, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and so on. The results showed that the concentration of nitrate concentration has a tiny effect on the Pb(II) adsorption and the kinetic adsorption experiments showed that CoFe2O3 and NiFe2O3 took less time to achieve the equilibrium state than Fe2O3 without doping And the isotherm batch experiments showed that Langmuir model matched well with the data of Fe2O3, Freundlich model fitted well in CoFe2O3 and NiFe2O3 experiments data, indicating that cobalt/nickel doping changes the adsorption mechanism. XPS analysis showed that the hydroxyl at surface played an important role in Pb(II) removal and the hydrogen bond was replaced by metal-oxygen bond. Furthermore, the adsorption capacities of, CoFe2O3 and NiFe2O3 for Pb(II) removal were 136.0 mg/g and 97.5 mg/g respectively, which were superior to pristine Fe2O3 (93.9 mg/g). This study clearly showed that CoFe2O3 and NiFe2O3 are promising candidates for lead ion removal in aqueous solution.

Electrochemical sensing of hydrogen peroxide using nitrogen-doped graphene/porous iron oxide nanorod composite

In this work, iron oxide nanomaterials with different shapes and structures were used as active materials for electrode. The proposed sensitive and non-enzymatic H2O2 biosensor, based on N-doped graphene/porous Fe2O3 NRs (N-rGO/Fe2O3 NRs), exhibits good stability and reproducibility under the optimal experimental conditions. Furthermore, this H2O2 biosensor was also utilized to detect H2O2 in real sample (orange juice) and high selectivity towards H2O2 was found. Therefore, the porous N-rGO/Fe2O3 NRs composite is thought of as a potential material in biosensing and bioanalysis.

Environmental oxidative aging of iron oxide nanoparticles

The environmental aging of functional iron oxide nanomaterials, especially those used in biomedical applications, may have significant consequences for both their mechanism of action and their safety profile. However, to date, there has been no way to systematically measure this property, and the problem has been largely overlooked. We show here that a recently proposed “center of gravity” method for determining the composition of magnetite (Fe3O4) and maghemite (γ-Fe2O3) mixtures via 57Fe Mössbauer spectroscopy can be applied to the matter. We show that a long-established diffusion model can be used to characterize the oxidative aging process, yielding a parametric (and therefore predictive) description of the magnetite-to-maghemite oxidation processes occurring within the nanoparticles.

The role of high-valent (Mo and V) cations in defect spinel iron oxide nanomaterials: Toward improving Li-ion storage

Defect spinel Fe3-δO4 samples doped with high-valent Mo and V cations have been prepared by sol-gel auto-combustion rout with increasing concentrations of Mo and V, respectively. Energy Dispersive X-ray fluorescence (EDXRF) and Attenuated Total Reflection Fourier transform Infrared (ATR-FTIR) spectroscopies have verified the compositions of the samples and the oxidation states of the metal cations. Synchrotron Radiation X-ray Powder Diffraction (SR-XRPD) patterns were measured at MCX beamline of ELETTRA synchrotron. Structure and microstructure of the samples were studied by the Rietveld method. Increasing densities of vacancies were found to be generated by the high-valent Mo and V cations which were correlated to the lattice parameter, crystallite size and microstrain of each sample. The hysteresis loops were measured at room temperature using the Vibrating Sample Magnetometer (VSM) and good agreement was found between the Fe-cation distributions revealed from Rietveld adjustments and those predicted by the saturation magnetization (Ms) measurements. The High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the proposed isotropic crystallite size model implemented in the Rietveld adjustments. Finally, the results presented herein show agreement with previous works on iron oxide materials used as intercalation cathode for Li-ion batteries and predict better performance for the current Mo- and V-doped defect spinel.

Antimicrobial efficacy of green synthesized iron oxide nanoparticles

This paper reports experimental details for preparation of poly-dispersed hematite (Fe2O3) nanoparticles using Nyctanthes arbor tristis flower extract at physiological pH and room temperature. The bio-inspired fabricated iron oxide nanomaterial is characterized by XRD patterns which reveal the formation of a high crystalline quality with rhombohedral structure having hematite phase. It is observed that XRD peak intensity is affected by the concentration of precursor. The FT-IR analysis reveals the existence of Fe-O bonding in the synthesized nanoparticles. The FE-SEM analysis reveals the nanostructure which is found to be poly-dispersed bead like agglomerates. The synthesized nanoparticles exhibit potential antimicrobial efficacies against Kleb. pneumoniae and Staph. aureus. Also the minimum inhibitory concentrations of the synthesized nanoparticles have been determined.

Triple Stimuli-Responsive Magnetic Hollow Porous Carbon-Based Nanodrug Delivery System for Magnetic Resonance Imaging-Guided Synergistic Photothermal/Chemotherapy of Cancer

The premature leakage of anticancer drugs during blood circulation may the damage immune system, normal cells, and tissues. Constructing targeted nanocarriers with pH, glutathione, and NIR triple-responsive property can effectively avoid the leakage of anticancer drugs before they arrive at the targeted site. In this paper, magnetic hollow porous carbon nanoparticles (MHPCNs) were successfully fabricated as nanocarrier. Poly(γ-glutamic acid) was used to cap the pores of MHPCNs. The photothermal conversion property of carbon and iron oxide (Fe3O4) nanomaterials was utilized to perform photothermal therapy to overcome multidrug-resistance produced by chemotherapy. The biodistribution of nanoparticles was investigated by magnetic resonance imaging. Experiments in vivo confirm the efficient accumulations of nanoparticles at tumor sites. Meanwhile, tumor growth was effectively inhibited via synergistic photothermal/chemotherapy with minimal side effects.

Template-assisted fabrication of tunable aspect ratio, biocompatible iron oxide pillar arrays

The extensive use of iron oxide nanomaterials in biomedical applications has prompted the development of a novel substrate for evaluating cell behaviour. This study examines the fabrication of tuneable length iron oxide pillar arrays using the porous nanochannels of anodic aluminium oxide membranes, and evaluates the biocompatibility of the substrate. The electroformed iron pillars were found to conform to the template channels with slightly larger iron oxide pillar diameters, due to the presence of an oxide shell. The biocompatibility was then confirmed with WST-1 proliferation and viability assay of cultured KT98 murine neural/progenitor stem cells on the surface of the pillar array; with no significant difference observed between viable cells after seven days of culture on iron oxide pillars, flat iron oxide, and tissue culture polystyrene. The physical properties of the pillar arrays were linked to the adhesion and spreading of the cells, and found that cells cultured on the pillar arrays had reduced spreading in comparison to tissue culture polystyrene control. In addition, it was found that protein expression was unaffected by culture on iron oxide substrates. The results of this study indicate that iron oxide pillar arrays are suitable to extended cell studies.

New Perspectives on Biomedical Applications of Iron Oxide Nanoparticles.

Iron oxide nanomaterials are considered promising tools for improved therapeutic efficacy and diagnostic applications in biomedicine. Accordingly, engineered iron oxide nanomaterials are increasingly proposed in biomedicine, and the interdisciplinary researches involving physics, chemistry, biology (nanotechnology) and medicine have led to exciting developments in the last decades. The progresses of the development of magnetic nanoparticles with tailored physico-chemical and surface properties produced a variety of clinically relevant applications, spanning from magnetic resonance imaging (MRI), drug delivery, magnetic hyperthermia, to in vitro diagnostics. Notwithstanding the wellknown conventional synthetic procedures and their wide use, along with recent advances in the synthetic methods open the door to new generations of naked iron oxide nanoparticles possessing peculiar surface chemistries, suitable for other competitive biomedical applications. New abilities to rationally manipulate iron oxides and their physical, chemical, and biological properties, allow the emersion of additional possibilities for designing novel nanomaterials for theranostic applications.

Multifunctional Porous Iron Oxide Nanoagents for MRI and Photothermal/Chemo Synergistic Therapy.

Nanoagents of integrating multiple imaging and therapeutic modalities have attracted tremendous attention for biomedical applications. Herein, we synthesize porous hollow Fe3O4 as a theranostic agent for MRI and combined photothermal/chemo cancer therapy. The as-prepared porous iron oxide nanoagents allow for T2-weighted MR imaging. Interestingly, we demonstrate that the porous structure endows the nanoagents an outstanding photothermal property for cancer cell killing, in comparison with other types of iron oxide nanomaterials. Under the exposure of an NIR laser, the heat produced by porous Fe3O4 can accelerate the release of the loaded drug (e.g., DOX) to enhance chemotherapeutic efficacy, promoting the ablation of cancer cells with synergistic photothermal/chemotherapy.