Concentrations Of Magnetite Nanoparticles Research Articles

Magnetite nanoparticles from representative coal fired power plants in China: Dust removal capture and their final atmospheric emission

Information on the emission of coal combustion-sourced magnetite nanoparticles (MNPs) is lacking, which is critical for their health-related risks. In this study, MNPs in coal fly ashes (CFAs) from various coal-fired power plants (CFPPs) in China equipped with various dust removal devices were extracted and quantified using single particle ICP-MS. The number concentrations of MNPs in CFAs captured by dust removal increased with stage, while their size decreased. Among all the dust removal devices, electrostatic-fabric-integrated precipitators showed the best removal of MNPs. Furthermore, throughout all the coal combustion by-products in a typical CFPP, MNPs in EFA (fly ash escaped from the stack) showed the highest number concentration (1.2 × 107 particles/mg) and lowest size (78 nm). Although the mass of CFA escaping through the stack is extremely low, it still had an emission rate of 1.9 × 1015 particles/h, contributing 3.56 % of the total emissions of MNPs in number. In addition, the purity of MNPs and their associated toxic metals showed a size-dependent variation pattern. As the particle size of MNPs decreased, the proportion of Fe in MNPs increased from 43 % in bottom ash (BA) to 84 % in EFA, while the abundance of trace toxic metals in EFA was 3.3 times higher than that of BA. These MNPs with the highest purity can adsorb elevated concentrations of toxic metals, and can be discharged directly into the atmosphere, posing a risk of synergistic toxicity.

Within-city spatial variations in PM2.5 magnetite nanoparticles and brain cancer incidence in Toronto and Montreal, Canada.

Magnetite nanoparticles are small, strongly magnetic iron oxide particles which are produced during high-temperature combustion and friction processes and form part of the outdoor air pollution mixture. These particles can translocate to the brain and have been found in human brain tissue. In this study, we estimated associations between within-city spatial variations in concentrations of magnetite nanoparticles in outdoor fine particulate matter (PM2.5) and brain cancer incidence. We performed a cohort study of 1.29 million participants in four cycles of the Canadian Census Health and Environment Cohort in Montreal and Toronto, Canada who were followed for malignant brain tumour (glioma) incidence. As a proxy for magnetite nanoparticle content, we measured the susceptibility of anhysteretic remanent magnetization (χARM) in PM2.5 samples (N = 124 in Montreal, N = 110 in Toronto), and values were assigned to residential locations. Stratified Cox proportional hazards models were used to estimate hazard ratios (per IQR change in volume-normalized χARM). ARM was not associated with brain tumour incidence (HR = 0.998, 95% CI 0.988, 1.009) after adjusting for relevant potential confounders. Although we found no evidence of an important relationship between within-city spatial variations in airborne magnetite nanoparticles and brain tumour incidence, further research is needed to evaluate this understudied exposure, and other measures of exposure to magnetite nanoparticles should be considered.

Controlled Release of the Anticancer Drug Cyclophosphamide from a Superparamagnetic β-Cyclodextrin Nanosponge by Local Hyperthermia Generated by an Alternating Magnetic Field.

A β-cyclodextrin (β-CD) nanosponge (NS) was synthesized using diphenyl carbonate (DPC) as a cross-linker to encapsulate the antitumor drug cyclophosphamide (CYC), thus obtaining the NSs-CYC system. The formulation was then associated with magnetite nanoparticles (MNPs) to develop the MNPs-NSs-CYC ternary system. The formulations mentioned above were characterized to confirm the deposition of the MNPs onto the organic matrix and that the superparamagnetic nature of the MNPs was preserved upon association. The association of the MNPs with the NSs-drug complex was confirmed through field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, dynamic light scattering, ζ-potential, atomic absorption spectroscopy, X-ray powder diffraction, selected area electron diffraction, and vibrating-sample magnetometer. The superparamagnetic properties of the ternary system allowed the release of CYC by utilizing magnetic hyperthermia upon the exposure of an alternating magnetic field (AMF). The drug release experiments were carried out at different frequencies and intensities of the magnetic field, complying with the "Atkinson-Brezovich criterion". The assays in AMF showed the feasibility of release by controlling hyperthermia of the drug, finding that the most efficient conditions were F = 280 kHz, H = 15 mT, and a concentration of MNPs of 5 mg/mL. CYC release was temperature-dependent, facilitated by local heat generation through magnetic hyperthermia. This phenomenon was confirmed by DFT calculations. Furthermore, the ternary systems outperformed the formulations without MNPs regarding the amount of released drug. The MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays demonstrated that including CYC within the magnetic NS cavities reduced the effects on mitochondrial activity compared to those observed with the free drug. Finally, the magnetic hyperthermia assays showed that the tertiary system allows the generation of apoptosis in HeLa cells, demonstrating that the MNPs embedded maintain their properties to generate hyperthermia. These results suggest that using NSs associated with MNPs could be a potential tool for a controlled drug delivery in tumor therapy since the materials are efficient and potentially nontoxic.

Magnetic Chitosan Bionanocomposite Films as a Versatile Platform for Biomedical Hyperthermia.

Responsive magnetic nanomaterials offer significant advantages for innovative therapies, for instance, in cancer treatments that exploit on-demand delivery on alternating magnetic field (AMF) stimulus. In this work, biocompatible magnetic bionanocomposite films are fabricated from chitosan by film casting with incorporation of magnetite nanoparticles (MNPs) produced by facile one pot synthesis. The influence of synthesis conditions and MNP concentration on the films' heating efficiency and heat dissipation are evaluated through spatio-temporal mapping of the surface temperature changes by video-thermography. The cast films have a thickness below 100µm, and upon exposure to AMF (663kHz, 12.8 kA m-1), induce exceptionally strong heating, reaching a maximum temperature increase of 82 °C within 270 s irradiation. Further, it is demonstrated that the films can serve as substrates that supply heat for multiple hyperthermia scenarios, including: i) non-contact automated heating of cell culture medium, ii) heating of gelatine-based hydrogels of different shapes, and iii) killing of cancerous melanoma cells. The films are versatile components for non-contact stimulus with translational potential in multiple biomedical applications.

Fabrication and characterization of magnesium implants coated with magnetic nanoparticles-wollastonite-hydroxyapatite for medical and sports injury applications: Finite element analysis

Recently, wollastonite nanoceramics were considered a suitable choice for the orthopedic applications in terms of the presence of silicon, and calcium ions. Using the nanoceramics for the coatings of orthopedic application was increased to facilitate the possibility of stabilization and integration with the host tissue and the regeneration of bone tissues. Using the ceramic coatings was extensively improved due to their biological properties. The present investigation delves into the utilization of innovative wollastonite nanoceramics (WS) fortified with magnetite nanoparticles (MNPs) as coatings for biomechanical implants. The study focuses on evaluating the bioactivity and mechanical attributes of electrophoretic coatings while characterizing their phase and structure through the employment of X-ray diffraction (XRD) and scanning electron microscope (SEM). The coatings are also evaluated for bioactivity and biodegradation in simulated body fluid (SBF) and phosphate-buffered saline (PBS) for 21 days. Additionally, the mechanical properties of the coatings are simulated using Finite Element Analysis (FEA) to predict porosity and elastic modulus. The presence of wollastonite with silica nanoparticles in a magnesium alloy significantly enhances bone formation, as evidenced by the highest degree of apatite formation observed in the alloy containing 10% wollastonite. This particular composition resulted in a remarkable 29% increase in apatite growth. These findings highlight the potential of incorporating wollastonite with silica nanoparticles to promote and improve bone formation processes. The results indicate that the specimen coated with a 10% concentration of magnetic nanoparticles (MNPs) exhibits favorable mechanical performance and desirable biological behavior, making it suitable for use in sports biomechanics implants. The results indicate that the specimen treated with a greater concentration of MNPs demonstrates advantageous mechanical characteristics and desirable biological responses, rendering it a promising candidate for the production of sports and orthopedic prostheses.

X-ray Computed Tomography (CT) to Scan the Structure and Characterize the Mud Cake Incorporated with Various Magnetic NPs Concentration: An Application to Evaluate the Wellbore Stability and Formation Damage

The X-ray computed tomography method has provided unrivalled data about the characterization and evolution of the internal/external structure of materials by analyzing CTN and non-destructive imaging approach. Applying this method on the appropriate drilling-fluid ingredients plays a significant role in generating proper mud cake quality to stabilize wellbore, and avoid formation damage and filtration loss by preventing drilling fluid invasion into the formation. In this study, smart-water drilling mud containing different concentrations of magnetite nanoparticles (MNPs) was used to assess the filtration loss properties and formation impairment. Conventional static filter press, non-destructive X-ray computed tomography (CT) scan images and high-resolution quantitative measurement of CT number method were used to estimate the filtrate volume and characterize the filter cake layers, hence evaluating the reservoir damage through hundreds of merged images. The CT scan data were combined with the HIPAX and Radiant viewer digital image processing. The variation in CT number of mud cake samples under different concentrations of MNPs and without MNPs concentration were analyzed, and hundreds of 3D images as a cross-sectional profile were used. This paper highlights the importance of MNPs property in terms of minimizing filtration volume and improving mud cake quality and thickness, and hence improving the wellbore stability. From the results, a notable reduction of filtrate drilling mud volume and mud cake thickness to 40.9% and 46.6%, respectively, were recorded for drilling fluids incorporated with 0.92 wt.% of MNPs. However, this study asserts that optimal MNPs should be implemented to guarantee the best filtration property. As confirmed from the results, increasing the MNPs concentration beyond the optimal value (up to 2 wt.%) increased the filtrate volume and mud cake thickness by 3.23 and 33.3%, respectively. CT scan profile images show two layers of mud cake produced from water-based drilling fluids possessing 0.92 wt.% MNPs. The latter concentration was found to be the optimal additive of MNPs as it caused a decrease in filtration volume, mud cake thickness, and pore spaces within the structure of the mud cake. Using the optimum MNPs, the CT number (CTN) shows a high CTN and density material, and uniform compacted thin mud cake structure (0.75 mm). The produced thin mud cake layer reveals the precipitation or exchange of elemental/mineral composition during fluid-solid interaction. These results confirm that MNPs could help in avoiding or reducing the formation damage, driving away drilling fluid from the formation, and improving borehole stability.

Functionalized Magnetite Nanoparticles: Characterization, Bioeffects, and Role of Reactive Oxygen Species in Unicellular and Enzymatic Systems.

The current study evaluates the role of reactive oxygen species (ROS) in bioeffects of magnetite nanoparticles (MNPs), such as bare (Fe3O4), humic acids (Fe3O4-HA), and 3-aminopropyltriethoxysilane (Fe3O4-APTES) modified MNPs. Mössbauer spectroscopy was used to identify the local surrounding for Fe atom/ions and the depth of modification for MNPs. It was found that the Fe3O4-HA MNPs contain the smallest, whereas the Fe3O4-APTES MNPs contain the largest amount of Fe2+ ions. Bioluminescent cellular and enzymatic assays were applied to monitor the toxicity and anti-(pro-)oxidant activity of MNPs. The contents of ROS were determined by a chemiluminescence luminol assay evaluating the correlations with toxicity/anti-(pro-)oxidant coefficients. Toxic effects of modified MNPs were found at higher concentrations (>10-2 g/L); they were related to ROS storage in bacterial suspensions. MNPs stimulated ROS production by the bacteria in a wide concentration range (10-15-1 g/L). Under the conditions of model oxidative stress and higher concentrations of MNPs (>10-4 g/L), the bacterial bioassay revealed prooxidant activity of all three MNP types, with corresponding decay of ROS content. Bioluminescence enzymatic assay did not show any sensitivity to MNPs, with negligible change in ROS content. The results clearly indicate that cell-membrane processes are responsible for the bioeffects and bacterial ROS generation, confirming the ferroptosis phenomenon based on iron-initiated cell-membrane lipid peroxidation.

Microfluidic Synthesis and Purification of Magnetoliposomes for Potential Applications in the Gastrointestinal Delivery of Difficult-to-Transport Drugs.

Magnetite nanoparticles (MNPs) have gained significant attention in several applications for drug delivery. However, there are some issues related to cell penetration, especially in the transport of cargoes that show limited membrane passing. A widely studied strategy to overcome this problem is the encapsulation of the MNPs into liposomes to form magnetoliposomes (MLPs), which are capable of fusing with membranes to achieve high delivery rates. This study presents a low-cost microfluidic approach for the synthesis and purification of MLPs and their biocompatibility and functional testing via hemolysis, platelet aggregation, cytocompatibility, internalization, and endosomal escape assays to determine their potential application in gastrointestinal delivery. The results show MLPs with average hydrodynamic diameters ranging from 137 ± 17 nm to 787 ± 45 nm with acceptable polydispersity index (PDI) values (below 0.5). In addition, we achieved encapsulation efficiencies between 20% and 90% by varying the total flow rates (TFRs), flow rate ratios (FRRs), and MNPs concentration. Moreover, remarkable biocompatibility was attained with the obtained MLPs in terms of hemocompatibility (hemolysis below 1%), platelet aggregation (less than 10% with respect to PBS 1×), and cytocompatibility (cell viability higher than 80% in AGS and Vero cells at concentrations below 0.1 mg/mL). Additionally, promising delivery results were obtained, as evidenced by high internalization, low endosomal entrapment (AGS cells: PCC of 0.28 and covered area of 60% at 0.5 h and PCC of 0.34 and covered area of 99% at 4 h), and negligible nuclear damage and DNA condensation. These results confirm that the developed microfluidic devices allow high-throughput production of MLPs for potential encapsulation and efficient delivery of nanostructured cell-penetrating agents. Nevertheless, further in vitro analysis must be carried out to evaluate the prevalent intracellular trafficking routes as well as to gain a detailed understanding of the existing interactions between nanovehicles and cells.

Effect of pH and zeta potential of Pickering stabilizing magnetite nanoparticles on the features of magnetized polystyrene microspheres

AbstractStyrene as a monomer was emulsified in water using several magnetite nanoparticles concentration and pH values. Emulsified styrene drops were used as templates for polymerization, in presence of water soluble free radical initiator, and formation of composite particles. Styrene template drops stabilization was verified by light as well as scanning electron microscopy imaging, which ensured the participation of the particles in building up a mechanical barrier to stop oil drops coalescence. Furthermore, the produced polystyrene composites were strongly attracted to an external magnet. The difference in particles size as a function of pH was elucidated using zeta potential measurements, which indicated dominance of pH on the hydrophilicity of the particles and consequently the extent of emulsification, which in turn affected the size of the obtained microspheres. Under some circumstances, capsules were formed instead of particles. Thereby, it can be concluded that the magnetic microspheres are optimally formed at pH 2.3 independently of the magnetite content used.

An intravenous application of magnetic nanoparticles for osteomyelitis treatment: An efficient alternative.

The infection of bone and bone marrow is called osteomyelitis. Treatment is difficult since antibiotics can not reach with enough concentration to the infected area. For the first time in this study, we have developed gentamicin-loaded magnetic gelatin nanoparticles (GMGNPs) for nanocarrier-mediated and magnetically targeted osteomyelitis therapy. Gelatin, genipin, and magnetite were used for preparation of that novel carrier system due to their biodegradable and biocompatible properties. Cross-linking degree of gelatin nanoparticles, concentration of magnetite nanoparticles, and adsorbed drug amount were optimized. Furthermore, nanoparticles were characterized and the drug release profile was determined. The osteomyelitis model was constituted in the proximal tibia of rats. The therapeutic potential of GMGNPs on rats was monitored via X-Ray radiography and hematological and histopathological analyses were performed. According to the results, 110.3±8.2µg gentamicin/mg GMGNPs were used, hydrodynamic size was measured as 253.7±11.8nm, and GMGNPs have controlled drug release profile. Based on in vivo and ex vivo studies, after six doses of GMGNPs treatment, abscess began to heal and the integrity of periost and bone began to reconstruct. In conclusion, it can be suggested that GMGNPs could provide efficient therapy for osteomyelitis.

Efficient non-contact heat generation on flexible, ternary hydroxyapatite/curdlan/nanomagnetite hybrids for temperature controlled processes.

The ternary HAp/curdlan/nanomagnetite hybrids with ceramic and polymer phase incorporation of magnetite nanoparticles (MNPs) were fabricated to study their heating ability under action of the alternating magnetic field (AMF), 808nm near infrared laser radiation (NIR) and their synergic stimulation. The energy conversion was evaluated in terms of the specific absorption rate (SAR) as a function of the MNPs concentration in composites and to estimate their potential in temperature-controlled regenerative processes and hyperthermia. Measurements were carried out on dry and Ringer's solution soaked composite materials in order to mimic in situ conditions. It was found that the MNPs release during prolonged experiment is limited and has no significant effect on energy conversion emphasizing stability of the hybrids. Incorporation of the MNPs in polymer phase of the hybrid can additionally limit particle leaking as well as plays a role as insulating layer for the heat dissipation lowering the risk of sample overheating. In general, it was shown that maximum temperature of hybrid can be achieved in a relatively short time of exposure to stimulating factors whereas its control can be done through optimization of experiment conditions. MNPs incorporation into the curdlan (polymer phase) lead to strengthening of the mechanical properties of the whole network.

Heat Transfer in Hairpin Heat Exchanger using Magnetite/Water Nanofluid

The present work deals with heat transfer augmentation in a Hair-Pin heat exchanger using magnetite/water nanofluid at volume concentrations of 0.004%, 0.006% and 0.008% under turbulent flow, the effect of different concentration of magnetite nanoparticles are added in pure water as basefluid on heat transfer coefficient and pressure drop in a hair-pin heat exchanger for counteract flow arrangement are investigated. The magnetite/water nanofluid is flowing through the inner tube and Reynolds number considered is in the range of 16000 to 30000. The results showed that there is 25-33% enhancement in heat transfer coefficient at 0.008% to the water at Reynolds number range of 16000 to 30000.

Physical characterization and uptake of iron oxide nanoparticles of different prostate cancer cells

Abstract Among nanoparticles, magnetic nanoparticles are the most appealing candidate for diagnosis and cancer therapy. The researchers are tempting to improve the particles properties, including the size, shape, coating, and magnetic behavior or heating characteristics. Core shell type of magnetic nanoparticle is an important property that modulates their internalization via normal and cancer cells. In this study, magnetite nanoparticles (MNP) covered by N-(2-aminoethyl)-3-aminopropyltriethoxysilane (aminosilane – APTES) were synthesized by co-precipitation of aqueous solution of ferric chloride and ferrous sulfate iron salts with ammonium hydroxide as a base and functionalized by APTES to increase the viability and affinity of the particles to the cancer cells. The structural and morphological properties of these particles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR). 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT assay) was carried out, to check the viability of the cells treatment with MNP and APTES-MNP. To study the cellular uptake in vitro, two prostate cell lines were investigated: PC3 as a cancerous cell line and BPH1 as a benign epithelial cell line (normal cells). Both cell lines were incubated for 24 h with different concentrations of MNP and APTES-MNP (100 and 500 μg/ml and one untreated sample as control). TEM and flow cytometry (FC) analyses were subsequently carried out to monitor the cellular uptake of MNP and APTES-MNP. FC data revealed an increase in cell granularity following the treatment with high concentration of the particles. Data showed that PC3 cancer cells take up more APTES-MNP with respect to control cells than BPH1 benign cells and in contrast BPH1 cell uptake MNP correlated to control cells more efficient than PC3 cells. The results from FC and TEM analyses demonstrate increasing of affinity of particles to cancer cell line (PC3). In this project we investigated the effect of surface functionalization of NP to affinity of the MNP and APTES-MNP on PC3 cells as a malignancy prostate cell and BPH1 benign cells as a normal cells. This approach may help to optimize the efficiency of hyperthermia for prostate cancer through internalization of particles to the cells or attaching to the membrane.

Fabrication of Magnetically Stirrable Anisotropic Microparticles via the Microfluidic Method

AbstractA one‐step strategy to fabricate magnetically stirrable microparticles with geometric/chemical anisotropies via a microfluidic technique combined with partial phase separation is presented. Monodisperse oil‐in‐water microemulsions composed of magnetite nanoparticles (MNPs) and two polymers, polystyrene and poly(d,l‐lactide‐co‐glycolide) (PLGA), dissolved in chloroform are generated using the microfluidic method. Upon incubating the microemulsions in pure water at ambient conditions, the solvent contained in the microemulsions is gradually removed and partial phase separation between the two polymers occurs spontaneously. In the meantime, the microemulsion droplets are vertically aligned due to the density difference of the two polymer phases. During the spontaneous phase separation, the MNPs become unstable and the aggregated MNPs segregate downward by gravity to the denser PLGA phase. After complete removal of the solvent, the resulting particles adopt geometric/chemical anisotropies, and they are magnetically rotatable under an external magnetic field. It is demonstrated that the morphology of the anisotropic particles can be controlled readily by adjusting the ratio of the two polymers as well as the concentration of MNPs. It is believed that the developed method based on the partial phase separation and the gravity‐induced segregation of the MNPs enables large‐scale production of magnetically stirrable microparticles.

Study of Nanocomposite Permittivity on the Basis of Magnetite Nanoparticles (Fe3O4) and Polymeric Matrix: Polyethylene and Polystyrene in Electromagnetic Field

This paper deals with the investigation results of nanocomposite permittivity based on magnetite nanoparticles and a polymeric matrix in electromagnetic field. Dependencies of real and imaginary parts of nanocomposite permittivity on the frequency of the electromagnetic field and size and concentration of magnetite nanoparticles have been found, and the dependence of imaginary part of permittivity on the real one has been determined. The Cole-Cole type has the dependence of the imaginary part of permittivity on the real one at high frequencies of electromagnetic field (at small values of the real part of permittivity) and hyperbolic behavior at small frequencies of the electromagnetic field (at large values of the real part of permittivity). Refraction index, loss angle tangent, and penetration depth of the nanocomposite.

Dielectric relaxations of nanocomposites composed of HEUR polymers and magnetite nanoparticles

We investigate the dynamics of nanocomposites composed of hydrophobically modified ethoxylated urethanes (HEUR) and magnetite nanoparticles (MNPs) as dry films. We employed dielectric relaxation spectroscopy (DRS) in combination with differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC). The three techniques reveal a strong heterogeneity of the matrix of the nanocomposites, consisting of (i) a crystalline poly(ethyleneoxide) PEO bulk phase, (ii) an amorphous PEO portion, and (iii) small PEO crystallites which experience different constraints than the PEO bulk phase. TSDC and DRS reveal a very high direct current (DC)-conductivity of the pure matrix, which increases with MNPs concentration. The increase of the DC-conductivity is not related to an increase of the segmental mobility, but most likely to the change of the morphology of the hydrophobic domains of the polymer matrix, due to the formation of large MNPs clusters. Indeed, the MNPs neither influence the segmental dynamics of the polymer nor the phase behavior of the polymer matrix. The addition of MNPs slightly increases the activation energy related to the γ-relaxation of the polymer. This effect might be related to the changes in nano-morphology as demonstrated by the slight increase of the degree of crystallinity. The analysis of the DRS data with the electrical modulus M″(ω) and the derivative ε″der formalism allow us to identify a low-frequency process in addition to the conductivity relaxation. This low-frequency dispersion is also revealed by TSDC. It is most likely related to the Maxwell-Wagner-Sillars relaxation, which typically occurs in systems which feature phase separation. The detailed investigation of the dielectric properties of these novel nanocomposites with increasing MNPs concentration will be useful for their practical application, for example as absorbers of electromagnetic waves.

Multi-stage freezing of HEUR polymer networks with magnetite nanoparticles.

We observe a change in the segmental dynamics of hydrogels based on hydrophobically modified ethoxylated urethanes (HEUR) when hydrophobic magnetite nanoparticles (MNPs) are embedded in the hydrogels. The dynamics of the nanocomposite hydrogels is investigated using dielectric relaxation spectroscopy (DRS) and neutron spin echo (NSE) spectroscopy. The magnetic nanoparticles within the hydrophobic domains of the HEUR polymer network increase the size of these domains and their distance. The size increase leads to a dilution of the polymers close to the hydrophobic domain, allowing higher mobility of the smallest polymer blobs close to the "center". This is reflected in the decrease of the activation energy of the β-process detected in the DRS data. The increase in distance leads to an increase of the size of the largest hydrophilic polymer blobs. Therefore, the segmental dynamics of the largest blobs is slowed down. At short time scales, i.e. 10(-9) s < τ < 10(-3) s, the suppression of the segmental dynamics is reflected in the α-relaxation processes detected in the DRS data and in the decrease of the relaxation rate Γ of the segmental motion in the NSE data with increasing concentration of magnetic nanoparticles. The stepwise (multi-stage) freezing of the small blobs is only visible for the pure hydrogel at low temperatures. On the other hand, the glass transition temperature (Tg) decreases upon increasing the MNP loading, indicating an acceleration of the segmental dynamics at long time scales (τ∼ 100 s). Therefore, it would be possible to tune the Tg of the hydrogels by varying the MNP concentration. The contribution of the static inhomogeneities to the total scattering function Sst(q) is extracted from the NSE data, revealing a more ordered gel structure than the one giving rise to the total scattering function S(q), with a relaxed correlation length ξNSE = (43 ± 5) Å which is larger than the fluctuating correlation length from a static investigation ξSANS = (17.2 ± 0.3) Å.

Enhanced oxygen transfer rate and bioprocess yield by using magnetite nanoparticles in fermentation media of erythromycin.

BackgroundMagnetite nanoparticles have widespread biomedical applications. In the aerobic bioprocesses, oxygen is a limiting factor for the microbial metabolic rate; hence a high availability of oxygen in the medium is crucial for high fermentation productivity. This study aimed to examine the effect of using magnetite nanoparticles on oxygen transfer rate in erythromycin fermentation culture.MethodsMagnetite nanoparticles were synthetized through co-precipitation method. After observing the enhanced oxygen transfer rate in deionized water enriched with magnetite nanoparticles, these nanoparticles were used in the media of by Saccharopolyspora erythraea growth to explore their impact on erythromycin fermentation titer. Treatments comprised different concentrations of magnetite nanoparticles, (0, 0.005, 0.02 v/v).ResultsIn the medium containing 0.02 v/v magnetite nanoparticles, KLa was determined to be 1.89 time higher than that in magnetite nanoparticle-free broth. An improved 2.25 time higher erythromycin titer was obtained in presence of 0.02 v/v nanoparticles.ConclusionsOur results, demonstrate the potential of magnetite nanoparticles for enhancing the productivity of aerobic pharmaceutical bioprocesses.

Evaluation of in vitro mutagenicity and genotoxicity of magnetite nanoparticles

For successful application of nanomaterials in bioscience, it is essential to understand the biological fate and potential toxicity of nanoparticles. The aim of this study is to evaluate the genetic safety of magnetite nanoparticles (MNPs) (Fe(3)O(4)) in order to provide their diverse applications in life sciences, such as drug development, protein detection, and gene delivery. Concentrations of 10 ppm, 30 ppm, and 70 ppm (10-70 μg/mL) of the MNPs of 8.0 ± 2.0 nm were used. Characterization of MNPs was done with transmission electron microscopy (TEM), X-Ray Diffractometry (XRD) and a vibrating sample magnetometer (VSM). The MNPs mutagenic potential was evaluated using the Salmonella Ames test with Salmonella strains TA100, TA2638, TA102, and TA98 in the presence and the absence of metabolic activation with S9-liver extract. Genetic mutations at the chromosomal level and extent of DNA damage using the alkaline Comet assay were applied to peripheral blood lymphocytes and HEK-293 cell lines respectively. There were significant changes in the results of the Salmonella mutagenicity test at the 70 ppm concentration of MNPs which might reflect their mutagenic activity at higher concentrations. Cytogenetic evaluation revealed the absence of genetic mutations at the chromosomal level. The extent of DNA damage quantified by Comet assay and the mutagenicity study using Ames test were significantly correlated for the MNPs. Our results indicated that magnetite nanoparticles with the defined physicochemical properties caused apparent toxicity at higher concentrations of 30 ppm and 70 ppm without chromosomal abnormalities under the experimental conditions of this study.

Magnetite nanoparticles with high heating efficiencies for application in the hyperthermia of cancer

Magnetic hyperthermia is a safe method for cancer therapy. A gap-type alternating current magnetic field (100 kHz, 100–300 Oe) is expected to be clinically applicable for magnetic hyperthermia. In this study, magnetite nanoparticles (MNPs) varying in size from 8 to 413 nm were synthesized using a chemical coprecipitation and an oxidation precipitation method to find the optimum particle size that shows a high heating efficiency in an applied magnetic field. The particles' in vitro heating efficiency in an agar phantom at an MNP concentration of 58 mg Fe/ml was measured in an applied magnetic field. In a magnetic field of 120 Oe, the temperature increase (Δ T) of the agar phantom within 30 s was 9.3 °C for MNPs with a size of 8 nm, but was less for the other samples, while in a magnetic field of 300 Oe, Δ T = 55 °C for MNPs with a size of 24 nm, and Δ T = 25 °C for MNPs with a size of 8 nm. The excellent heating efficiency of MNPs with a size of 24 nm in a magnetic field of 300 Oe may be due to a combination of the effects of both relaxation and hysteresis losses of the magnetic particles. It is believed that MNPs with a size of 8–24 nm will be useful for the in situ hyperthermia treatment of cancer.