Amount Of Iron Oxide Nanoparticles Research Articles

Nanostructured Lipid Carrier Co-Loaded with Docetaxel and Magnetic Nanoparticles: Physicochemical Characterization and In Vitro Evaluation.

Lung cancer is currently the most prevalent cause of cancer mortality due to late diagnosis and lack of curative therapies. Docetaxel (Dtx) is clinically proven as effective, but poor aqueous solubility and non-selective cytotoxicity limit its therapeutic efficacy. In this work, a nanostructured lipid carrier (NLC) loaded with iron oxide nanoparticles (IONP) and Dtx (Dtx-MNLC) was developed as a potential theranostic agent for lung cancer treatment. The amount of IONP and Dtx loaded into the Dtx-MNLC was quantified using Inductively Coupled Plasma Optical Emission Spectroscopy and high-performance liquid chromatography. Dtx-MNLC was then subjected to an assessment of physicochemical characteristics, in vitro drug release, and cytotoxicity. Dtx loading percentage was determined at 3.98% w/w, and 0.36 mg/mL IONP was loaded into the Dtx-MNLC. The formulation showed a biphasic drug release in a simulated cancer cell microenvironment, where 40% of Dtx was released for the first 6 h, and 80% cumulative release was achieved after 48 h. Dtx-MNLC exhibited higher cytotoxicity to A549 cells than MRC5 in a dose-dependent manner. Furthermore, the toxicity of Dtx-MNLC to MRC5 was lower than the commercial formulation. In conclusion, Dtx-MNLC shows the efficacy to inhibit lung cancer cell growth, yet it reduced toxicity on healthy lung cells and is potentially capable as a theranostic agent for lung cancer treatment.

Preparation and characterization of electrospun magnetic poly(ether urethane) nanocomposite mats: Relationships between the viscosity of the polymer solutions and the electrospinning ability

The aim of this research was to obtain electrospun fibers from poly(ether urethane) (PEU) and poly(ether urethane)-iron oxide nanoparticles (PUC) based on the correlation between the rheological characteristics and the electrospinnability of the polymer suspensions. Firstly, our goal was to explore the domain of polymer concentration suitable for electrospinning using the rheological data, in order to control the formation of electrospun fibers and to avoid the defects such as beaded fibers or sprayed droplets. By increasing the polymer concentration in the system, the morphology was changed from droplets to a mixture of droplets and nanofibers, to uniform, defect free fibers, showing a randomly ordered orientation of the fibers. Then, the influence of the amount of iron oxide nanoparticles on the rheological behaviour of nanocomposites was also envisaged. The diameter of the electrospun PUC fibers decreased with the increase of the iron oxide nanoparticles content as it was revealed by scanning electron microscopy (SEM) and confocal Raman microscopy investigations. Moreover, the magnetic properties were also envisaged and it was evidenced that the electrospun nanocomposite mats displayed superparamagnetic properties with low coercivity and remanence and reversible hysteresis behaviour. These results will allow further to choose the electrospinning parameters for an optimal design of future polyurethane nanocomposite mats for targeted applications, especially those where high surface area-to-volume or length-to-diameter ratios are required.

Tuning magnetic response and ionic conductivity of electrospun hybrid membranes for tissue regeneration strategies

AbstractElectrospun membranes play an increasing role in tissue regeneration base on their suitable morphological features. The implementation of active response, such as magnetically responsiveness or piezo‐ionic features can further improve tissue regeneration by better resembling varying microenvironment during cell culture. In this context, this work reports on the development of poly(vinylidene fluoride) (PVDF) oriented (O) and randomly (R) oriented electrospun fibers containing different amounts of iron oxide nanoparticles (Fe3O4, NP) or ionic liquid (IL) choline bis(trifluoromethylsulfonyl) imide ([Chol][TFSI]) (5, 10, and 15% wt).The addition of the fillers did not result in significant differences in the morphology of the electrospunfibers or their degradation temperature. PVDF‐O + IL fibers present diameters between 0.98 and 1.28 μm, crystallinity between 52% and 59% and electroactive PVDF β‐phase content between 73% and 88%. PVDF‐R + IL fiber diameter ranges from 1.29 to 1.97 μm, crystallinity between 46% and 55% and β‐phase content between 79% and 82%. The PVDF‐O + Fe3O4 fiber diameter varied between 0.81 and 1.07 μm, crystallinity between 48% and 59% and β‐phase between 73% and 81%. The effective NP content in the fibers followed a nearly linear relation with the theoretical values, with experimental yields between 93% and 97%. Further, the inclusion of IL into PVDF matrix leads to an increase of the ionic conductivity up to 2.6 × 10−9 S.cm−1 for the sample with 15% IL content. Finally, the potential of the materials for tissue engineering was evaluated, by analyzing its cytotoxicity for L929 fibroblasts, with cell viability results of over 90% indicating the cytocompatibility of these materials.

Rational synthesis of polymer coated inorganic nanoparticles-MWCNT hybrids via solvophobic effects

The efficient synthesis of inorganic nanoparticle-carbon nanotube hybrids requires the development of models and synthetic guidelines that can be used to maximise the interactions between both nanomaterials. Herein we report the application of the Hansen surface energy based solubility parameter theory as a model for the selection of solvents that can maximise the interactions between iron oxide nanoparticles and MWCNTs. To achieve this, we synthesized iron oxide nanoparticle-MWCNT hybrid materials in three different solvents and characterized their composition with TGA. The solvent was found to have a significant impact in the final amount of iron oxide composition of the hybrids. The Hansen surface energy based solubility parameters of MWCNTs were characterized via inverse gas chromatography and were used to evaluate the interactions between the MWCNTs and the solvent media. Under this model we expected that large differences between the Hansen surface energy based solubility parameters of solvents and MWCNTs would be correlated with larger incorporation of iron oxide nanoparticles in the hybrids. The amount of iron oxide nanoparticles found in the hybrids were indeed consistent with the predictions of the Hansen surface energy based solubility parameter theory making it a powerful tool for the design of nanoparticle-carbon nanotube hybrids.

Composite Materials Based on Iron Oxide Nanoparticles and Polyurethane for Improving the Quality of MRI.

Polyether urethane (PU)-based magnetic composite materials, containing different types and concentrations of iron oxide nanostructures (Fe2O3 and Fe3O4), were prepared and investigated as a novel composite platform that could be explored in different applications, especially for the improvement of the image quality of MRI investigations. Firstly, the PU structure was synthetized by means of a polyaddition reaction and then hematite (Fe2O3) and magnetite (Fe3O4) nanoparticles were added to the PU matrices to prepare magnetic nanocomposites. The type and amount of iron oxide nanoparticles influenced its structural, morphological, mechanical, dielectric, and magnetic properties. Thus, the morphology and wettability of the PU nanocomposites surfaces presented different behaviours depending on the amount of the iron oxide nanoparticles embedded in the matrices. Mechanical, dielectric, and magnetic properties were enhanced in the composites’ samples when compared with pristine PU matrix. In addition, the investigation of in vitro cytocompatibility of prepared PU nanocomposites showed that these samples are good candidates for biomedical applications, with cell viability levels in the range of 80–90%. Considering all the investigations, we can conclude that the addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work.

Electrical and acoustic investigation of partial discharges in two types of nanofluids

Measurements of partial discharges in liquid dielectrics are important for prediction of a serious failure of electrical equipment. Recent research findings show that application of nanoparticles in dielectric liquids may increase their resistance to partial discharges. However, physical properties of a host liquid are expected to play a decisive role in the effective suppression of partial discharges by nanoparticles. In this paper, a transformer oil prepared by a gas-to-liquid technology and a standard naphthenic transformer oil are doped with an equal amount of iron oxide nanoparticles. Determination of basic physical properties of the oils and the nanofluids is followed by an experimental investigation of partial discharges under various alternating voltage levels. The detection of partial discharges is approached by two independent methods, electrically and acoustically. Both methods revealed occurrence of partial discharges in the gas-to-liquid oil at higher voltages, as compared with the naphthenic oil. Acoustic emission energy is found one order of magnitude greater in the gas-to-liquid oil than in the naphthenic oil. The acoustic wave propagation dependence on the physical properties of the liquid is considered in the qualitative explanation of the observed phenomenon. The presence of nanoparticles can suppress partial discharges in the naphthenic oil, but not in the gas-to-liquid oil.

Free‐Standing N‐doped Reduced Graphene Oxide Papers Decorated with Iron Oxide Nanoparticles: Stable Supercapacitor Electrodes

AbstractIn this study, graphene oxide paper is obtained via vacuum‐assisted filtration of graphene oxide solution to prepare self‐standing electrodes for supercapacitors. Simultaneous reduction and N‐doping of graphene oxide paper are performed by chemical reduction followed by thermal annealing. Influence of different reduction techniques on the electrochemical properties of the self‐standing papers is investigated. N‐doped reduced graphene oxide papers are decorated with iron oxide nanoparticles to increase the energy density of the material. Increasing the amount of iron oxide nanoparticles in the composite paper results in enhanced capacitance. In the galvanostatic charge‐discharge measurements, iron oxide/N‐doped reduced graphene oxide electrode exhibits specific capacitance of 203 F g−1at 0.5 mA cm−2. This value is remarkable since the electrode has a high mass loading of 2 mg cm−2, which shows that the electrode can be used for practical purposes. Moreover, these electrodes operate in a wide potential window (1.6 V) and exhibit 79 % capacitance retention at 10000 cycles.

3D crystallographic alignment of alumina ceramics by application of low magnetic fields

Non-cubic crystals exhibit anisotropic physical and functional properties. Microscopic crystallites as constituents of polycrystalline materials are randomly oriented, thus polycrystalline ceramics lack the anisotropic properties of their monocrystalline counterparts. We propose a technology that exploits the synergy between magnetic alignment and colloidal ceramics processing, and enables to independently tune the orientation of grains in different sample regions by infinitesimal magnetic fields (<10 mT). The grain pivot mechanism enables the emulation of single crystals, as well as the creation of large complex-shaped ceramic elements with designed crystallographic landscapes and spatially and directionally tuned properties. Ultra-high magnetic response arises from magnetic shape anisotropy of platelet-shaped seed crystallites coated with small amounts of iron oxide nanoparticles. To control crystallographic growth directions during subsequent annealing procedures, the seeds are dispersed and aligned in a matrix of chemically identical, but much finer spherical particles. This technology opens an avenue to remarkably improve structural and functional properties of ceramic elements employed in numerous industrial applications.

Magnetic Field-Induced Polymerization of Molecularly Imprinted Polymers

In this work, we developed a novel approach for the preparation of molecularly imprinted polymer (MIP) coatings directly onto magnetic multicore nanoparticles (MMCs) using alternating magnetic fields to trigger the polymerization reaction. MIPs were synthesized with rhodamine 123 (R123) as model template molecule, methacrylic acid as functional monomer, and trimethylolpropane trimethacrylate as cross-linker. The amount of iron oxide nanoparticles and the composition of the polymerization mixture were optimized to enable the thermal polymerization of a thin MIP shell on each MMC using electromagnetic heating without altering the properties of the recognition layer. The thickness of the polymerized MIP layer grafted onto the MMCs was fine-tuned by adjusting the dose of electromagnetic field (101.4 kHz, total power dissipation = 105 W). The resulting magnetic multicore MIP nanoparticles (MMC-MIPs) were characterized by Fourier transform infrared and X-ray diffraction spectroscopy, transmission electron micro...

Facile Synthesis of Iron Oxide/Graphene Nanocomposites Using Liquid Phase Plasma Method.

Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of iron oxide nanoparticles onto graphene sheet. Iron oxide nanoparticles with the size of 50 nm were precipitated with uniform dispersion on the surface of graphene sheet. The amount of iron oxide nanoparticles precipitated on graphene sheets increased with increasing LPP process times. The XPS, Raman and EDX analyses showed that the iron oxide/graphene composites synthesized by the LPP process.

Lysosomal iron liberation is responsible for the vulnerability of brain microglial cells to iron oxide nanoparticles: comparison with neurons and astrocytes

Iron oxide nanoparticles (IONPs) are used for various biomedical and neurobiological applications. Thus, detailed knowledge on the accumulation and toxic potential of IONPs for the different types of brain cells is highly warranted. Literature data suggest that microglial cells are more vulnerable towards IONP exposure than other types of brain cells. To investigate the mechanisms involved in IONP-induced microglial toxicity, we applied fluorescent dimercaptosuccinate-coated IONPs to primary cultures of microglial cells. Exposure to IONPs for 6 h caused a strong concentration-dependent increase in the microglial iron content which was accompanied by a substantial generation of reactive oxygen species (ROS) and by cell toxicity. In contrast, hardly any ROS staining and no loss in cell viability were observed for cultured primary astrocytes and neurons although these cultures accumulated similar specific amounts of IONPs than microglia. Co-localization studies with lysotracker revealed that after 6 h of incubation in microglial cells, but not in astrocytes and neurons, most IONP fluorescence was localized in lysosomes. ROS formation and toxicity in IONP-treated microglial cultures were prevented by neutralizing lysosomal pH by the application of NH4Cl or Bafilomycin A1 and by the presence of the iron chelator 2,2′-bipyridyl. These data demonstrate that rapid iron liberation from IONPs at acidic pH and iron-catalyzed ROS generation are involved in the IONP-induced toxicity of microglia and suggest that the relative resistance of astrocytes and neurons against acute IONP toxicity is a consequence of a slow mobilization of iron from IONPs in the lysosomal degradation pathway.

Uptake and metabolism of iron and iron oxide nanoparticles in brain astrocytes

Astrocytes are considered key regulators of the iron metabolism of the brain. These cells are able to rapidly accumulate iron ions and various iron-containing compounds, store iron efficiently in ferritin and also export iron. The present short review summarizes our current knowledge of the molecular mechanisms involved in the handling of iron by astrocytes. Cultured astrocytes efficiently take up iron as ferrous or ferric iron ions or as haem by specific iron transport proteins in their cell membrane. In addition, astrocytes accumulate large amounts of iron oxide nanoparticles by endocytotic mechanisms. Despite the rapid accumulation of high amounts of iron from various iron-containing sources, the viability of astrocytes is hardly affected. A rather slow liberation of iron from accumulated haem or iron oxide nanoparticles as well as the strong up-regulation of the synthesis of the iron storage protein ferritin are likely to contribute to the high resistance of astrocytes to iron toxicity. The efficient uptake of extracellular iron by cultured astrocytes as well as their strong up-regulation of ferritin after iron exposure also suggests that brain astrocytes deal well with an excess of iron and protect the brain against iron-mediated toxicity.

Ferritin up-regulation and transient ROS production in cultured brain astrocytes after loading with iron oxide nanoparticles

To investigate the cellular consequences of a prolonged cellular presence of large amounts of iron oxide nanoparticles (IONPs) as well as the fate of such particles in brain cells, cultured primary astrocytes were loaded for 4h with dimercaptosuccinate-coated IONPs. Subsequently, the IONP-treated cells were incubated for up to 7days in IONP-free medium and the cell viability, metabolic parameters and iron metabolism of the cells were investigated. Despite an up to 100-fold elevated specific cellular iron content, IONP-loaded cells remained viable throughout the 7day main incubation and did not show any substantial alteration in glucose and glutathione metabolism. During the incubation, the high cellular iron content of IONP-loaded astrocytes remained almost constant. Electron microscopy revealed that after 7days of incubation most of the cellular iron was still present in IONP-filled vesicles. However, the transient appearance of reactive oxygen species (ROS) as well as a strong increase in cellular levels of the iron storage protein ferritin suggest that at least some low-molecular-weight iron was liberated from the accumulated IONPs. These results demonstrate that even the prolonged presence of large amounts of accumulated IONPs does not harm astrocytes and that these cells store IONP-derived iron in ferritin.

Core/shell polymethyl methacrylate/polyethyleneimine particles incorporating large amounts of iron oxide nanoparticles prepared by emulsifier-free emulsion polymerization

A facile synthetic route for the preparation of magnetic poly(methyl methacrylate) (PMMA) core/polyethyleneimine (PEI) shell colloidal particles, possessing high saturation magnetization is reported. Bilayer oleic acid-stabilized iron oxide nanoparticles (bIOs) were designed to have both favorable encapsulation of iron oxide nanoparticles and interaction with protonated amine groups of PEI. The prepared particles had diameter ranging from 180 to 207 nm with narrow size distribution and displayed highly positive surface charges up to +47 mV. TEM revealed that the well-defined bIOs were successfully encapsulated inside the polymer core–shell colloids. Thermogravimetric analysis and magnetization study indicated that these colloidal particles had the magnetic material up to 80 wt % loading and exhibited superparamagnetic property with high saturation magnetization. Thus, they could be potentially useful in various applications, including magnetic separation, medical diagnostics, or drug delivery.

Electrospun PVC/Fe3O4 composite nanofibers for microwave absorption applications

In this paper we present a study on the microwave frequency properties of PVC/Fe3O4 composite nanofibers, with different amounts of iron oxide nanoparticles incorporate in PVC matrix. Using electrospinning where obtained composite nanofibers with diameters ranging between 100nm and 600nm. The transmission loss of PVC/Fe3O4 composites measured in the microwave frequency range of X-band were found to be below −15dB demonstrating that these materials can be used as protection material of electromagnetic radiation. The applied magnetic field significantly modifies the measured scattering parameters in our samples case in a rather large domain of values for the field.

Transmission of Light through Magnetic Nanocavities

The transmission of light through a metallic film stack on a transparent substrate, perforated with a periodic array of cylindrical holes/nanocavities, is studied. The structure is fabricated by using self-assembled nanosphere lithography. Since one layer in the film stack is made of a ferromagnetic metal (iron), exposure of the structure to a solution containing iron oxide nanoparticles causes nanoparticle accumulation inside the nanocavities. This changes the dielectric constant inside the nanocavities and thus affects the light transmission. Simulations are in good agreement with experiment, and show large sensitivity of the response to the amount of iron oxide nanoparticles deposited. This could be used in various sensor applications.

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign.

Structural Organization of Iron Oxide Nanoparticles Synthesized Inside Hybrid Polymer Gels Derived from Alginate Studied with Small-Angle X-ray Scattering

The structural organization of iron oxide nanoparticles (NPs) obtained through in situ coprecipitation of iron salts in semi-interpenetrating polymer networks (semi-IPNs) constituted of alginate (Alg) and poly(N-isopropylacrylamide) (PNiPAAm) has been investigated by means of small-angle X-ray scattering and transmission electron microscopy. The oxidation reaction was repeated up to two times to increase the amount of iron oxide NPs formed. The results were compared to the synthesis of iron oxide nanoparticles in an alginate solution. It has been demonstrated that the polymeric gel acts as a spatial framework for iron oxide nanoparticles that controls their particle size distribution and that the application of repeating oxidation cycles does not increase the polydispersity of the iron oxide nanoparticles.