Crystalline Iron Oxide Nanoparticles Research Articles

Echinochloa frumentacea grains extract mediated synthesis and characterization of iron oxide nanoparticles: A greener nano drug for potential biomedical applications

Iron oxide nanoparticles have been used in diverse fields due to their significant applications. The synthesis of iron oxide nanoparticles using plant material extract is a simple, inexpensive and eco-friendly approach. The present study demonstrates the effective bio-synthesis of iron oxide nanoparticles using grains extract of Echinochloa frumentacea. GC-MS analysis report revealed the information about the phytochemicals in aqueous grains extract. The formation of iron oxide nanoparticles was confirmed using UV–visible, XRD, FTIR, HRTEM, EDX, and mapping analyses. The UV–visible spectrum of iron oxide nanoparticles showed the SPR band at 289 nm. The XRD studies confirmed the formation of high crystalline iron oxide nanoparticles. HRTEM analysis showed that the formed nanoparticles were rectangular and triangular in shape and the size ranged between 20 and 40 nm. The iron oxide nanoparticles revealed significant antibacterial activity against the microbes such as Staphylococcus aureus and Salmonella typhi at 150 μg/mL and morphological changes were observed. The high concentration of nanoparticles exhibited 24 and 27 mm zone of inhibition on S. typhi and S. aureus, respectively. We observed the role of biological activities such as antioxidant, anti-inflammatory, and anti-diabetic properties of nanoparticles, and they showed excellent bioactive properties even at a low IC50 value. The antioxidant, anti-inflammatory and anti-diabetic analyses showed high activity at 95.10, 92.10 and 91.68% for 80 μg/mL concentration, respectively. Moreover, the iron oxide nanoparticles exhibited high cytotoxicity (94.36%) against A549 cancer cells and no toxicity against HEK293 normal cells which showed the biocompatibility of nanoparticles. The larvicidal and insecticidal activities of nanoparticles showed the maximum mortality at 48 h in 100 ppm and 72 h in 75, 100 μg/kg, respectively. The morphological and structural changes in larvae and insects validated the effective biological activities of iron oxide nanoparticles. The plant growth study results recommended that the lower concentration of nanoparticles at 60 ppm was helpful for the germination of seeds and growth of root and stem in the Vigna unguiculata plant. Finally, the study results suggested that the synthesized iron oxide nanoparticles can potentially be useful in pharmaceutical, agricultural, targeted drug delivery and biomedical applications.

Glucose-coated superparamagnetic iron oxide nanoparticles prepared by metal vapor synthesis can target GLUT1 overexpressing tumors: In vitro tests and in vivo preliminary assessment.

Superparamagnetic iron oxide nanoparticles (SPIONs) coated with glucose (Glc-SPIONs) were prepared by a new approach called Metal Vapor Synthesis (MVS) and their morphological/structural features were investigated by transmission electron microscopy (TEM) and dynamic light scattering. TEM analysis revealed the presence of small roundish crystalline iron oxide nanoparticles in the organic amorphous phase of glucose, The particles were distributed in a narrow range (1.5 nm-3.5 nm) with a mean diameter of 2.7 nm. The hydrodynamic mean diameter of the Glc-SPIONs, was 15.5 nm. From 4 mg/mL onwards, there was a constant level of positive contrast in a T1-weighted sequence. In vitro experiments were performed in three cell lines: pancreatic cancer (PSN-1), human thyroid cancer (BCPAP), and human embryonic kidney non-tumor cells. We evaluated GLUT1 expression in each cell line and demonstrated that the exposure time and concentration of the Glc-SPIONs we used did not affect cell viability. PSN-1 cells were the most effective at internalizing Glc-SPIONs. Although significantly higher than the control cells, a lower Fe content was detected BCPAP cells treated with Glc-SPIONs. To confirm the involvement of GLUT1 in Glc-SPIONs internalization, cellular uptake experiments were also conducted by pre-treating cancer cells with specific GLUT1 inhibitors, All the inhibitors reduced the cancer cell uptake of Glc-SPIONs In vivo tests were performed on mice inoculated with Lewis lung carcinoma. Mice were treated with a single i.v. injection of Glc-SPION and our results showed a great bioavailability to the malignant tissue by the i.v. administration of Glc-SPIONs. Glc-SPIONs were efficiently eliminated by the kidney. To the best of our knowledge, our study demonstrates for the first time that Glc-SPIONs prepared with MVS can be electively internalized by tumor cells both in vitro and in vivo by exploiting one of the most universal metabolic anomalies of cancer.

Magnetic Ordering in Ultrasmall Potassium Ferrite Nanoparticles Grown on Graphene Nanoflakes.

Magnetic nanoparticles are central to the development of efficient hyperthermia treatments, magnetic drug carriers, and multimodal contrast agents. While the magnetic properties of small crystalline iron oxide nanoparticles are well understood, the superparamagnetic size limit constitutes a significant barrier for further size reduction. Iron (oxy)hydroxide phases, albeit very common in the natural world, are far less studied, generally due to their poor crystallinity. Templating ultrasmall nanoparticles on substrates such as graphene is a promising method to prevent aggregation, typically an issue for both material characterization and applications. We generate ultrasmall nanoparticles, directly on the carbon framework by the reaction of a graphenide potassium solution, charged graphene flakes, with iron(II) salts. After mild water oxidation, the obtained composite material consists of ultrasmall potassium ferrite nanoparticles bound to the graphene nanoflakes. Magnetic properties as evidenced by magnetometry and X-ray magnetic circular dichroism, with open magnetic hysteresis loops near room temperature, are widely different from classical ultrasmall superparamagnetic iron oxide nanoparticles. The large value obtained for the effective magnetic anisotropy energy density Keff accounts for the presence of magnetic ordering at rather high temperatures. The synthesis of ultrasmall potassium ferrite nanoparticles under such mild conditions is remarkable given the harsh conditions used for the classical syntheses of bulk potassium ferrites. Moreover, the potassium incorporation in the crystal lattice occurs in the presence of potassium cations under mild conditions. A transfer of this method to related reactions would be of great interest, which underlines the synthetic value of this study. These findings also give another view on the previously reported electrocatalytic properties of these nanocomposite materials, especially for the sought-after oxygen reduction/evolution reaction. Finally, their longitudinal and transverse proton NMR relaxivities when dispersed in water were assessed at 37 °C under a magnetic field of 1.41 T, allowing potential applications in biological imaging.

Green & sustainable synthetic route of obtaining iron oxide nanoparticles using Hylocereus undantus (pitaya or dragon fruit)

In the present communication, we have synthesized iron oxide nanoparticles through a greener method. The adopted method is highly efficient because of its sustainable and eco- friendly approach. The conventional routes of synthesis require high temperature and large volume of solvents which are not suitable for environment applications. The adopted method is applied to synthesize magnetic and optical iron oxide nanoparticles. The iron oxide nanoparticles were prepared using the water extract of Hylocereus undantus (pitaya) which acts as a reducing agent. The as obtained nanoparticles obtained were characterized through PXRD (Powder X-ray Diffraction), UV–Vis (Ultraviolet– Visible Spectroscopy), TEM (Transmission electron microscopy), SAED (Selected Area Electron Diffraction), FT-IR (Fourier transform infrared spectroscopy), DLS (Dynamic Light Scattering) and TGA (Thermogravimetric analysis). According to various methods of characterization, it was revealed that the nanoparticles were spherical in shape and the size were in the range of 10–15 nm. The major lattice planes present in the synthesized crystalline iron oxide nanoparticles were known through XRD and SAED. The synthesized nanoparticles were uniform in size as revealed through DLS. TGA was performed to testify the degradation of nanoparticles under high temperatures. So, the iron oxide nanoparticles formed were spherical, uniform, ultrafine, reusable and magnetic in nature.

Role of hydration and micellar shielding in tuning the structure of single crystalline iron oxide nanoparticles for designer applications

AbstractDifferent physicochemical properties of nanoscale iron oxides have been useful in enabling various applications. Desirable biochemical, magnetic, and catalytic properties result from the structure and size of the iron oxide polymorph particles. To produce monodispersed single crystalline particles, PS‐b‐P2VP reverse micelle templating has proven to be a convenient low temperature method. Here, Raman spectroscopy and quantitative nanomechanical mapping analysis are used to provide a full picture of the formation and transformation processes that occur within the reverse micelle templates. Surprisingly, shielding of the hygroscopic FeCl precursor salt against hydration rather than complexation with the pyridine is responsible for the formation of ‐FeO particles. Additionally, micelle shielded nanoparticles not only exhibited a uniform size distribution and ordered dispersion, but also an increased transition temperature for the to ‐phase transition, up to 700 C, making them much more stable than traditional nanoparticles. Using these key understandings of particle formation, nanoparticles can be tuned with composition ranging from a purely spinel (‐FeO, FeO) to a purely hexagonal phase (‐FeO), and varying ratios of the three phases, while maintaining a fixed particle size. Modifying parameters offer intriguing opportunities to tailor designer iron oxide nanoparticles for targeted applications with a facile and scalable technique.

Synergistic approach towards the sustainable management of heavy metals in wastewater using mycosynthesized iron oxide nanoparticles: Biofabrication, adsorptive dynamics and chemometric modeling study

In our study, novel mycosynthesis of ferromagnetic, monodispersed, spherical, crystalline iron oxide nanoparticles (IO-NPs) of 73.05 ± 15.47 nm were biofabricated using manglicolous fungi Aspergillus tubingensis (STSP 25) isolated from rhizospheric sediment samples of Avicennia officinalis which was sustainably utilised for the removal of Pb (II), Ni (II), Cu (II), and Zn (II) from wastewater. The elemental and XRD characterisation had shown Fe2O3 (hematite) nature of the IO-NPs which were aqua stable due to deposition of extracellular fungal bio molecules onto them. Initial batch adsorption studies revealed that at pH 6 in 313 K temp, 1 g/L of IO-NPs could able to remove >90 % of heavy metals from the aqueous matrix. This was further confirmed through muti-factor chemometric approach which involved RSM and ANN module. RSM and ANN analysis inferred that 98.0037 % of Pb (II), 96.4502 % of Ni (II), 92.1984 % of Cu (II), and 93.9913 % of Zn (II) ions were adsorbed from 9.66 mg/L of heavy metals on 1 g/L concentration of IO-NPs in 308.25 K temperature at pH 6. Adsorptive dynamics indicated the process of adsorption was kinetically spontaneous and thermodynamically it followed endothermic reaction, where metallic ions got chemisorbed on the monolayer interface of IO-NPs. The overall process followed the Langmuir isotherm model and Pseudo-second order kinetics. The Adsorbing potentiality of IO-NPs for Pb (II), Ni (II), Cu (II), and Zn (II) was found to be 9.206 mg/g, 9.666 mg/g, 8.335 mg/g and 9.106 mg/g respectively. Reusability study showed IO-NPs had high regeneration capability till five adsorption/desorption cycle.

Improving the Heating Efficiency of Iron Oxide Nanoparticles by Tuning Their Shape and Size

Magnetic nanoparticle-mediated hyperthermia is a very promising therapy for cancer treatment. In this field, superparamagnetic iron oxide nanoparticles have been commonly employed because of their intrinsic biocompatibility, but they present some limitations that restrict their heating efficiency (specific absorption rate, SAR). Therefore, we have investigated how tuning the size and shape of these iron oxide nanoparticles can be useful to enhance their hyperthermia responses. Monodisperse and crystalline iron oxide nanoparticles have been synthesized by thermal decomposition in two different shapes (spheres and cubes) in a wide range of sizes, ∼10–100 nm. We have thoroughly characterized them both structurally (X-ray diffraction and transmission electron microscopy) and magnetically (physical property measurement system), and then we have analyzed their heating efficiency using a combination of calorimetric and AC magnetometry measurements (0–800 Oe, 300 kHz). We have been able to delimit a range of opti...

A systematic study of the controlled generation of crystalline iron oxide nanoparticles on graphene using a chemical etching process.

Chemical vapor deposition (CVD) of carbon precursors employing a metal catalyst is a well-established method for synthesizing high-quality single-layer graphene. Yet the main challenge of the CVD process is the required transfer of a graphene layer from the substrate surface onto a chosen target substrate. This process is delicate and can severely degrade the quality of the transferred graphene. The protective polymer coatings typically used generate residues and contamination on the ultrathin graphene layer. In this work, we have developed a graphene transfer process which works without a coating and allows the transfer of graphene onto arbitrary substrates without the need for any additional post-processing. During the course of our transfer studies, we found that the etching process that is usually employed can lead to contamination of the graphene layer with the Faradaic etchant component FeCl3, resulting in the deposition of iron oxide FexOy nanoparticles on the graphene surface. We systematically analyzed the removal of the copper substrate layer and verified that crystalline iron oxide nanoparticles could be generated in controllable density on the graphene surface when this process is optimized. It was further confirmed that the FexOy particles on graphene are active in the catalytic growth of carbon nanotubes when employing a water-assisted CVD process.

Single step, phase controlled, large scale synthesis of ferrimagnetic iron oxide polymorph nanoparticles by thermal plasma route and their rheological properties

In this paper we report single step large scale synthesis of highly crystalline iron oxide nanoparticles viz. magnetite (Fe3O4) and maghemite (γ-Fe2O3) via gas phase condensation process, where micron sized iron metal powder was used asa precursor. Selective phases of iron oxide were obtained by variation of gas flow rate of oxygen and hence partial pressure of oxygen inside the plasma reactor. Most of the particles were found to possesses average crystallite size of about 20–30nm. The DC magnetization curves recorded indicate almost super-paramagnetic nature of the iron oxide magnetic nanoparticles. Further, iron oxide nanoparticles were analyzed using Raman spectroscopy, X-ray photoelectron spectroscopy and Mossbauer spectroscopy. In order to explore the feasibility of these nanoparticles for magnetic damper application, rheological studies have been carried out and compared with commercially available Carbonyl Iron (CI) particles. The nanoparticles obtained by thermal plasma route show improved dispersion which is useful for rheological applications.

Modulation of Magnetic Heating via Dipolar Magnetic Interactions in Monodisperse and Crystalline Iron Oxide Nanoparticles

In the pursuit of controlling the heat exposure mediated by magnetic nanoparticles, we provide new guidelines for tailoring magnetic relaxation processes via dipolar interactions. For this purpose, highly crystalline and monodisperse magnetic iron oxide nanocrystals whose sizes range from 7 to 22 nm were synthesized by thermal decomposition of iron organic precursors in 1-octadecene. The as-synthesized nanoparticles are soft nanomagnets, showing superparamagnetic-like behavior and SAR values which progressively increase with particle size, field frequency, and amplitude up to 3.6 kW/gFe. Our data show the influence of media viscosity, particle size, and concentration on dipolar interactions and consequently on the magnetic relaxation processes related to the heat release. Understanding the role of dipolar interactions is of great importance toward the use of iron oxide nanoparticles as efficient hyperthermia mediators.

Growth and characterizations of magnetic nanoparticles under hydrothermal conditions: Reaction time and temperature

Abstract Magnetic iron oxide nanoparticles with various sizes and magnetic properties were synthesized by using a hydrothermal method. The initial nanoparticles were obtained by co-precipitation of ferric and ferrous salts and then treated under a hydrothermal condition for 1–120 h at 160 °C. At reaction time of 12 h, further treatment on the particles was performed at 200 °C. The resultant nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD) and vibrating sample magnetometer. The images obtained by TEM showed that the particles are around spherical in shape. The mean size of particles increased from 14±4 nm to 74±9 nm as the reaction time was increased from 1 h to 120 h. From the XRD patterns, high crystalline iron oxide nanoparticles were obtained with increasing reaction time and temperature. The saturation magnetizations obtained from magnetization curves were found to be rising from 74.9 to 93.5 emu/g that is consistent with the bulk value of the magnetite.

Nanoscale size effect on surface spin canting in iron oxide nanoparticles synthesized by the microemulsion method

Uniformly sized and crystalline iron oxide nanoparticles (IONPs) with spinel structure and mean diameters of about 3, 6 and 9 nm were synthesized in high yield using the microemulsion route at room temperature. The nanoparticles (NPs) were stabilized in situ by organic surfactant molecules which acted both as a stabilizer of the microemulsion system and as a capping layer of the NP surface. NP size control was attained by careful adjustment of the preparation conditions. The structure, morphology and NP size distribution were investigated by x-ray diffraction, transmission electron microscopy and scanning electron microscopy. A particular effort was devoted in this work to study the effect of size and capping of these NPs on their magnetic structure by in-field Mössbauer spectroscopy at 4.2 K. The mean canting angle (relative to the applied field direction) of the Fe spins was observed to increase with decreasing NP size due to the enhanced surface-to-volume ratio. Comparing bare and capped NPs of the same diameter, we verified that the spin canting was not affected by the organic capping. This implied almost identical magnetic orientations of bare and capped NPs. Simultaneously, the capping material was capable of preventing agglomeration effects which can occur in case of direct particle contact. Using a core/shell model, we showed that spin canting originated from the surface shell of the NPs. Furthermore, the Mössbauer spectral parameters provided evidence for the existence of a high fraction of Fe3O4 (magnetite) in the IONP.

Highly crystalline superparamagnetic iron oxide nanoparticles (SPION) in a silica matrix

We report on magnetic properties of iron oxide nanoparticles in a silica matrix synthesized by the sol–gel method. The sample is characterized by using X-ray powder diffractometer (XRPD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and superconducting quantum interference device (SQUID) magnetometer. TEM reveals iron oxide nanoparticles (maghemite/magnetite) of small sizes of about 4nm, narrow size distribution and no particle agglomeration. The SQUID measurements show low blocking temperature TB=6K and superparamagnetic behavior above 30K. Obtained saturation magnetization MS=61.1emu/g is very high, among the highest values for iron oxides of particle size below 5nm. The field-cooled hysteresis measurements do not show displacement of the hysteresis loop thus indicating an absence of exchange bias, whereas AC susceptibility reveals non-interacting nanoparticles. The values of Keff and KS (effective and surface anisotropy constants) obtained in this work are smaller than those reported in the literature for systems where shell's disorder spin structure (surface effects) is observed. These results point to highly crystalline iron oxide nanoparticles with a low amount of internal defects and small surface disorder shell thickness which is uncommon for nanoparticles of this size. Superparamagnetic iron oxide nanoparticles (SPION) with such properties are convenient for the biomedical applications in targeted diagnostics and drug delivery.

Critical radius for exchange bias in naturally oxidized Fe nanoparticles

Details of synthesis and structural characterization of highly crystalline iron oxide nanoparticles are presented together with results on the magnetic investigation as a function of the temperature and applied field. Monodisperse Fe nanoparticles were prepared by thermal decomposition of iron pentacarbonyl in the presence of oleic acid. These iron nanoparticles were readily oxidized on exposure to air. The resulting nanocrystals have been identified as inverse spinels, being $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ the dominant phase of the small $5\text{\ensuremath{-}}\mathrm{nm}$ iron oxide nanocrystals, whereas the proportion of the ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ component gradually increases on increasing the particle size. The small particles volume resulted in finite-size effects, for instance, the magnetization deviates from the ${T}^{3∕2}$ Bloch's law. At the same time, high field irreversibility and shifted hysteresis loops after field-cooled processes have been detected, and attributed to a low-temperature surface spin-glass layer. Moreover, there is a critical diameter below which the surface spin-glass behavior and exchange bias effect abruptly disappear.