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Aim: Magnetic-mediated hyperthermia has emerged as a promising therapeutic approach for treating cancer. This technique employs the heat dissipated by the magnetic nanoparticles when subjected to an external varying magnetic field, to bring about localized hyperthermia in tumor tissues. Owing to their conducive and tuneable “physical, chemical, and magnetic” characteristics, cobalt ferrite (CoFe2O4) nanoparticles are recognized as emerging contenders. The aim of the present work was to enhance the magnetic characteristics and guarantee the efficacy of CoFe2 O4 nanoparticles in targeting and eliminating cancer cells. Methods: CoFe2O4 nanoparticles were synthesized using the chemical co-precipitation route and underwent rigorous structural, morphological, and magnetic characterization techniques. The synthesized particles were then subjected to in vitro studies to evaluate their cytotoxicity and antimicrobial susceptibility. Results: The characterization techniques confirmed the cubic structure, ferrite phase, and spherical and magnetic nature of CoFe2O4 nanoparticles. The zeta potential was found to be − 0.0048V (4.8 mV). Cytotoxicity analysis exhibited decreased cell viability with increasing concentrations of CoFe2O4 nanoparticles. Antimicrobial studies displayed good inhibiting properties. Conclusion: The zeta potential of the synthesized CoFe2O4 nanoparticles was found to be higher than that of the breast cancer cells (MCF-7) which proves the synthesized drug to be effective. The in vitro studies also disclose the efficacy of the drug over cancer cells.

Aim: Magnetic-mediated hyperthermia has emerged as a promising therapeutic approach for treating cancer. This technique employs the heat dissipated by the magnetic nanoparticles when subjected to an external varying magnetic field, to bring about localized hyperthermia in tumor tissues. Owing to their conducive and tuneable "physical, chemical, and magnetic" characteristics, cobalt ferrite (CoFe2O4) nanoparticles are recognized as emerging contenders. The aim of the present work was to enhance the magnetic characteristics and guarantee the efficacy of CoFe2 O4 nanoparticles in targeting and eliminating cancer cells. Methods: CoFe2O4 nanoparticles were synthesized using the chemical co-precipitation route and underwent rigorous structural, morphological, and magnetic characterization techniques. The synthesized particles were then subjected to in vitro studies to evaluate their cytotoxicity and antimicrobial susceptibility. Results: The characterization techniques confirmed the cubic structure, ferrite phase, and spherical and magnetic nature of CoFe2O4 nanoparticles. The zeta potential was found to be − 0.0048V (4.8 mV). Cytotoxicity analysis exhibited decreased cell viability with increasing concentrations of CoFe2O4 nanoparticles. Antimicrobial studies displayed good inhibiting properties. Conclusion: The zeta potential of the synthesized CoFe2O4 nanoparticles was found to be higher than that of the breast cancer cells (MCF-7) which proves the synthesized drug to be effective. The in vitro studies also disclose the efficacy of the drug over cancer cells. [ABSTRACT FROM AUTHOR]

This work investigated the efficiency of CoFe2O4 nanoparticles in removing diclofenac and naproxen drugs from aqueous solutions. At first, the Taguchi method was performed to choose the most important factors among the investigated factors affecting the removal efficacy of these drugs. Afterward, the optimal conditions of the effective factors were investigated and modeled by the central composite design-based response surface method. The results revealed that the maximum drug removal was obtained at pH = 7, temperature of 25 °C, adsorbent dosage of 215 mg, sonication time of 21 min, and diclofenac and naproxen concentrations of 15 mg L−1. The removal efficacy of diclofenac and naproxen under these optimal conditions was 99.42 % and 95.11 %, respectively. Based on the results, it is concluded that CoFe2O4 nanoparticles can be applied as an easy-available and effective adsorbent for removing diclofenac and naproxen from water samples.

In this work, a new magnetic sorbent (cobalt ferrite nanoparticles modified with choline chloride: p-aminophenol deep eutectic solvent) was synthesized and used in magnetic dispersive solid phase extraction of heavy metals (Zn, Ni, Cu, Pb, Hg, and Cr) before their determination with inductively coupled plasma–optical emission spectrometry. In this method, firstly, the proteins of milk sample were precipitated by using trichloroacetic acid. Then, the magnetic sorbent was added into the clear supernatant phase obtained from pervious step and the mixture was vortexed. After isolating the sorbent particles in the presence of an external magnet, the supernatant phase was discarded and the sorbent was eluted using µL-level of ammonia solution. Finally, the eluent phase was injected into analytical instrument for the quantitative analysis. Under the optimized extraction conditions, satisfactory results including low limits quantification (1.4–2.1 ng mL−1) and detection (0.42–0.63 ng mL−1), high extraction recoveries (66–82%), and good precision with relative standard deviations ≤ 3.2 and 3.9% for intra– and inter day precisions, respectively) were obtained. In the last step, the suggested approach was used to determine the selected analytes in various milk samples. [ABSTRACT FROM AUTHOR]

Current work describes eco-friendly synthesis of cobalt ferrite (CoFe2O4) nanoparticles utilizing the flower and leaves extract of Hibiscus rosa-sinensis by chemical co-precipitation method and explored the behavior of CoFe2O4 nanoparticles on humidity sensing for humidity range 15% to 98% at room temperature. The cubic spinel structure of synthesized CoFe2O4 nanoparticles suggests a porous complex shape with an average crystalline size of 23.85 nm. Elemental analysis reveals no signs of impurity. Thermogravimetric analysis and differential thermal analysis showed that the material experienced a transformation toward thermal stability. CoFe2O4 nanoparticles as sensing medium were found to have a practical sensitivity of 40% relative humidity in the atmosphere and a response/recovery time of 5.31/7.75 seconds, respectively. CoFe2O4 nanoparticles are stable over time, according to the findings. CoFe2O4 nanoparticles humidity sensing performance demonstrates their suitability for room temperature-based humidity sensors. A general representation of the synthesis of CoFe2O4 nanoparticles [ABSTRACT FROM AUTHOR]

Among the modern oncological therapies, one of the most promising is based on tumor hyperthermia with magnetic nanoparticles resulting from the crystallization of iron and cobalt oxides. We synthesized core–shell magnetic nanoparticles of perchlorate-CoxFe3−xO4 (x = 0; 0.5; 1.0) via the co-precipitation method and stabilized them in aqueous suspensions. Fine granulation of the dispersed ferrophase was revealed by Transmission Electron Microscopy and Dynamical Light Scattering, with FTIR data detailing the surface-interaction phenomena. X-ray diffractometry revealed specific crystallization features of inverse spinel lattice, providing crystallite size and lattice parameters dependent on the cobalt content. The results of the Vibrating Sample Magnetometry investigations indicated that cobalt doping has reduced the magnetic core size and increased the nanoparticle dimension, which could be the result of crystallization defects at the nanoparticle surface related to the presence of cobalt ions. A mathematical model was applied with a focus on the quantitative description of the temperature distribution around magnetic nanoparticles. Further development of our research will consider new cobalt ferrite nanoparticles with new cobalt contents and different organic coatings to contribute to their biocompatibility and stability in aqueous suspensions, as required by administration in living organisms. [ABSTRACT FROM AUTHOR]

We discuss the atomic structure of cobalt ferrite nanoparticles doped with Mn via an analysis based on combining atomic pair distribution functions with high energy X-ray diffraction and high-resolution transmission electron microscopy measurements. Cobalt ferrite nanoparticles are promising materials for metal–air battery applications. Cobalt ferrites, however, generally show poor electronic conductivity at ambient temperatures, which limits their bifunctional catalytic performance in oxygen electrocatalysis. Our study reveals how the introduction of Mn ions promotes the conductivity of the cobalt ferrite electrode. [ABSTRACT FROM AUTHOR]

AC induction heating properties of colloidal nano-aggregates of ferrimagnetic cobalt ferrite magnetic nanoparticles (MNPs) are reported in this study. Bio-compatible chitosan polymer-coated CoFe 2 O 4 MNPs are synthesized using a co-precipitation method. Powder X-ray diffraction indicates the formation of mixed spinel structures for the uncoated (CP) and chitosan-coated (CP–CHN) MNPs, which is also supported by the cation distributions obtained from the Mössbauer spectra. The presence of chitosan coating on the surface of the CP-CHN MNPs is confirmed using X-ray photoelectron and Fourier transform infrared spectroscopy studies. Transmission electron microscopy shows primary particle sizes of ∼13 nm, which is larger than the superparamagnetic size limit of the CoFe 2 O 4 MNPs. Hence, the CP and CP-CHN MNPs exhibit ferrimagnetic behaviour at room temperature with estimated saturation magnetization values of ∼77.4 emu/g and ∼74.4 emu/g, respectively. The average hydrodynamic diameter is found to be ∼90 ± 8 nm for an aqueous dispersion of the CP-CHN MNPs, which indicate the formation of colloidal nano-aggregates due to the ferrimagnetic interaction of the primary MNPs. The CP-CHN sample exhibits a significantly high AC induction heating efficiency of ∼267.2 ± 4.0 W/g Fe , where the higher heating efficiency is attributed to the combination of hysteresis and relaxation-mediated magneto-thermal energy conversion, as confirmed using Stoner-Wohlfarth model-based dynamic hysteresis loop calculations. Further, the heating efficiency decreases with increasing sample concentration due to an increase in dipolar interaction, which is confirmed using semi-empirical calculations, where a lowering of the initial susceptibility is observed at higher concentrations. The higher AC induction heating efficiency, coupled with the demonstrated significant bio-compatibility during in vitro cytotoxicity studies, make the cobalt ferrite nano-aggregates potential candidates for magnetic hyperthermia. [Display omitted] • Nano-aggregates of ferrimagnetic cobalt ferrite nanoparticles were synthesized. • The presence of chitosan coating was confirmed by FTIR and XPS. • The nano-aggregates exhibited good AC induction heating efficiency. • Heating efficiency decreased at higher concentration due to dipolar interaction. • Chitosan coated samples exhibited superior biocompatibility against L929 cell-line. [ABSTRACT FROM AUTHOR]

• The easily separable CoFe 2 O 4 NPs were facilely prepared. • The CoFe 2 O 4 exhibited excellent PMS activation performance towards CR degradation. • Various inorganic anions exerted little influence on the CoFe 2 O 4 /PMS system. • The CoFe 2 O 4 /PMS system performed well over a wide range of pH. • The CR degradation mechanism and ecotoxicological assessment was investigated. Development of an effective catalyst is essential to eliminate the risks to ecological environment and human health caused by the accumulation of azo dyes in environmental water. Herein, the cobalt ferrite (CoFe 2 O 4) nanoparticles (NPs), facilely prepared by a one-pot hydrothermal procedure, were developed for peroxymonosulfate (PMS) activation towards Congo red (CR) degradations. The key experimental parameters were comprehensively investigated to optimize the degradation performance for CR in CoFe 2 O 4 /PMS system. Under optimal conditions, the CoFe 2 O 4 NPs exhibited an excellent capability for PMS activation to degrade CR with the degradation efficiency of nearly 100 % in a wide range of pH values (3.0–9.0). The electron paramagnetic resonance (EPR) and quenching experiments confirmed that the entire CR degradation process was dominantly by the non-radical (1O 2) and surface-bound SO 4 ·−and ·OH. CoFe 2 O 4 NPs displayed the remarkable stability and reusability, with degradation efficiency of 85.5 % even after six recycles. The possible degradation pathway in CR degradation process was proposed, and the qualitative analysis and ecotoxicity of the degradation intermediates were investigated. This work provided a facile and green strategy to prepare a prospective catalyst for the efficient removal of azo dyes by PMS activation. [ABSTRACT FROM AUTHOR]

Osteosarcoma remains a worldwide concern due to the poor effectiveness of available therapies in the clinic. Therefore, it is necessary to find a safe and effective therapy to realize the complete resection of osteosarcoma and reconstruction of the bone defect. Magnetic hyperthermia based on magnetic nanoparticles can kill tumor cells by raising the temperature without causing the side effects of conventional cancer treatments. This research aims to design a high-performance magnetic hydrogel composed of gelatin methacrylate and highly magnetic cobalt ferrite (CFO) nanoparticles for osteosarcoma treatment. Specifically, CFO is surface functionalized with methacrylate groups (MeCFO). The surface modified CFO has good biocompatibility and stable solution dispersion ability. Afterward, MeCFO nanoparticles are incorporated into GelMA to fabricate a three-dimensional (3D) printable MeCFO/GelMA magnetic hydrogel and then photocross-linked by UV radiation. MeCFO/GelMA hydrogel has high porosity and swelling ability, indicating that the hydrogel possesses more space and good hydrophily for cell survival. The rheological results showed that the hydrogel has shear thinning property, which is suitable as a bioprinting ink to produce desired structures by a 3D printer. Furthermore, 50 μg/mL MeCFO not only decreases the cell activity of osteosarcoma cells but also promotes the osteogenic differentiation of mBMSCs. The results of the CCK-8 assay and live/dead staining showed that MeCFO/GelMA hydrogel had good cytocompatibility. These results indicated that MeCFO/GelMA hydrogel with potential antitumor and bone reconstruction functions is a promising therapeutic strategy after osteosarcoma resection.

Co-ferrite nanoparticles have been prepared by wet chemical route using micelles. Two sets of particles with sizes of ⁓100 nm and ⁓200 nm were obtained by varying the concentration of micelles. The morphological and crystallographic study of the particles was performed by scanning electron microscope (SEM) and x-ray diffractometer respectively. To check the suitability of the co-ferrite nanoparticles in magnetic hyperthermia therapy, various magnetic measurements were carried out in presence of AC and DC magnetic fields. To investigate the suitability of the particles in hyperthermia therapy hysteresis loss of the particles under the application of AC magnetic field with various frequencies has been carried out. The parabolic nature of power loss with the frequency of the applied AC field has been verified from experimental data. From various measurements, it appeared that the particles with an average size ~100 nm have better efficiency in view of hyperthermia therapy. A large value of the specific absorption rate (SAR) was found from the ac hysteresis of the particles. [ABSTRACT FROM AUTHOR]

Abstract Bioactive materials in combination with antibiotics have been widely developed for the treatment of bone infection. Thus, this work aims to characterize six biomaterials formulated with different concentrations of hydroxyapatite and cobalt ferrite nanoparticles, in addition to the antibiotic ciprofloxacin, using X-ray diffraction (XRD), scanning electron microscopy (SEM), and the antibiotic diffusion test on agar. Furthermore, in vivo biocompatibility and the reabsorption process of these materials were analyzed. XRD showed that both hydroxyapatite and cobalt ferrite present high crystallinity. The photomicrographs obtained by SEM revealed that composites have a complex surface, evidenced by the irregular arrangement of the hydroxyapatite and cobalt ferrite granules, besides demonstrating the interaction between their components. The antibiotic-diffusion test showed that all biomaterials produced an inhibition halo in Staphylococcus aureus cultures. For the biocompatibility study, composites were surgically implanted in the dorsal region of rabbits. At 15, 30, 70, and 100 days, biopsies of the implanted regions were performed. The biomaterials were easily identified during histological analysis and no significant inflammatory process, nor histological signs of toxicity or rejection by the adjacent tissue were observed. We can conclude that the biomaterials analyzed are biocompatible, degradable, and effective in inhibiting the in vitro growth of Staphylococcus aureus. Graphical abstract

Three-dimensional additive manufacturing methods are being continuously improved with great interest in low cost and small size radio frequency (RF) circuits. Recent developments in magnetically tunable microwave/RF components are attractive for externally controlled circuits without influencing RF characteristics. This letter focuses on additive manufacturing of ferroic nanomaterials along with their implementation in frequency-tuned RF circuits using an applied magnetic field. Extraction of the additively manufactured magneto-dielectric composite was performed at $S$ -band frequencies using least squares curve fitting of measured and simulated $S$ -parameters for annular ring resonator modes. Polylactide (PLA) material used for additive manufacturing was extracted to have $\varepsilon = 1.80 - j0.031$. Meanwhile, magnetic CoFe2O4 with 45-nm average nanoparticles size was extracted to have $\varepsilon $ = $3.10 - j0.084$ and $\mu $ = $1.70 - j0.145$ ; while Protopasta’s magnetic filament had $\varepsilon $ = $1.80 - j0.031$ and $\mu $ = $2.19 - j0.569$. The 3-D printed magnetic composite is used to design tunable annular ring resonators at 2.4 GHz with up to 38-MHz frequency tuning for an applied 1-kG magnetic field. [ABSTRACT FROM AUTHOR]

Among the modern oncological therapies, one of the most promising is based on tumor hyperthermia with magnetic nanoparticles resulting from the crystallization of iron and cobalt oxides. We synthesized core–shell magnetic nanoparticles of perchlorate-CoxFe3−xO4 (x = 0; 0.5; 1.0) via the co-precipitation method and stabilized them in aqueous suspensions. Fine granulation of the dispersed ferrophase was revealed by Transmission Electron Microscopy and Dynamical Light Scattering, with FTIR data detailing the surface-interaction phenomena. X-ray diffractometry revealed specific crystallization features of inverse spinel lattice, providing crystallite size and lattice parameters dependent on the cobalt content. The results of the Vibrating Sample Magnetometry investigations indicated that cobalt doping has reduced the magnetic core size and increased the nanoparticle dimension, which could be the result of crystallization defects at the nanoparticle surface related to the presence of cobalt ions. A mathematical model was applied with a focus on the quantitative description of the temperature distribution around magnetic nanoparticles. Further development of our research will consider new cobalt ferrite nanoparticles with new cobalt contents and different organic coatings to contribute to their biocompatibility and stability in aqueous suspensions, as required by administration in living organisms.

Magnetoactive polymer composites have garnered significant attention for their potential use in diverse applications, owing to their rapid and reversible response to external magnetic fields. By incorporating magnetic nanoparticles (MNPs) into an elastomeric matrix, these composites exhibit unique properties under static or alternating magnetic fields. In this context, thermo-polyurethane-based magnetic active composites are promising materials for developing microfluidic system components such as valves and peristaltic pumps. In the current study, we investigated the utilization of cobalt ferrite (CoFe 2 O 4) magnetic nanoparticles in conjunction with a non-toxic synthesis method for polyurethane. It was explored the impact, on the overall success of the process, of cobalt ferrite nanoparticles incorporation at various stages of the thermo-polyurethane (TPU) synthesis reaction. Finally, the effects of different amounts of MNPs on the physicochemical properties of the resulting composites and their behavior as actuators under the influence of a magnetic field, was investigated. Our studies reveal that the actuator response of the composites increases proportionally with the percentage of MNPs present. Finally, the performance of a TPU/7.5% (V /V) CoFe2O4 composite strip as a flow control actuator within a microfluidic system was evaluated. This actuator responds to magnetic fields by bending, resulting in a 10% reduction in flow rate of microfluidic system. Reversing the magnetic field restores the flow rate to its initial value. Our cyclic tests illustrate the actuator's capacity to locally and temporarily modulate the microfluidic system's resistance. When combined with tailored TPU elasticity, these materials show significant potential for the fabrication of microfluidic valves and pumps. [Display omitted] • MNP timing addition is crucial for successful synthesis of TPU/CoFe 2 O 4 composite. • The effect of cobalt ferrite content on the material properties was evaluated. • All the prepared magnetic composites exhibit magnetic-actuator behavior. • Composite strip cuts flow by 10% in microfluidics, reversible with a magnetic field. • Cyclic tests show potential of TPU/CoFe 2 O 4 membranes in microfluidics flow control. [ABSTRACT FROM AUTHOR]

AC induction heating mediated magnetic fluid hyperthermia of superparamagnetic nanoparticles (MNPs) is being widely explored for localized thermo-therapy of tumours. One of the primary hindrances for rapid adaptation of this technique is the loss of heating efficiency when the MNPs are placed within the viscous tissue medium, which necessitates undesired increase in MNP concentrations or exposure time during practical applications. With an objective to mitigate this, here we report the viscosity independent magnetic hyperthermia properties of biocompatible ultrafine (average size ∼ 2.5 nm) chitosan-coated superparamagnetic CoFe 2 O 4 MNPs synthesized using a low-cost co-precipitation technique. The presence of the chitosan coating is confirmed from Fourier transform infrared and X-ray photoelectron spectroscopy. The superparamagnetic nature of the synthesized MNPs at 300 K is confirmed from Mössbauer spectroscopy, isothermal and temperature dependent magnetization studies. Experimental findings indicate a higher field-induced heating efficiency for the chitosan-coated MNPs due to superior colloidal stability. The ultrafine size, combined with higher anisotropy energy density, results in viscosity independent Nèel relaxation-dominated magneto-thermal energy conversion for the CoFe 2 O 4 MNPs. Experimental results reveal negligible loss of heating efficiency due to partial abrogation of Brownian relaxation when the chitosan-coated MNPs are immobilized in a tissue-equivalent agar medium, which is beneficial for practical applications. The heating efficiency of ∼72.1 ± 2.8 W/g Fe (at 33.1 kA/m and 126 kHz), obtained in the present study for the chitosan-coated MNPs, is higher than the previously documented values for ultrafine CoFe 2 O 4 MNPs, which is useful for reducing the exposure time during practical applications. Further, the chitosan coating rendered the ultrafine CoFe 2 O 4 MNPs bio-compatible against L929 cell line. The satisfactory magnetic fluid hyperthermia efficiency, negligible room temperature coercivity, retention of the field-induced heating efficiency in tissue-equivalent agar medium due to Nèel-dominated relaxation dynamics and superior biocompatibility, make the chitosan-coated ultrafine CoFe 2 O 4 MNPs an attractive candidate for practical MFH applications. [Display omitted] • Ultrafine superparamagnetic CoFe 2 O 4 MNPs prepared by co-precipitation. • CoFe 2 O 4 MNPs were coated with chitosan polymer, as confirmed by FTIR and XPS. • The coated MNPs exhibited good alternating field induced heating efficiency. • No loss in heating efficiency in agar medium due to Nèel dominated relaxation. • Coated MNPs exhibited superior biocompatibility against L929 cell lines. [ABSTRACT FROM AUTHOR]

In this paper, we present a study by computer simulation on superparamagnetic hyperthermia with CoFe2O4 ferrimagnetic nanoparticles coated with biocompatible gamma-cyclodextrins (γ-CDs) to be used in alternative cancer therapy with increased efficacy and non-toxicity. The specific loss power that leads to the heating of nanoparticles in superparamagnetic hyperthermia using CoFe2O4–γ-CDs was analyzed in detail depending on the size of the nanoparticles, the thickness of the γ-CDs layer on the nanoparticle surface, the amplitude and frequency of the alternating magnetic field, and the packing fraction of nanoparticles, in order to find the proper conditions in which the specific loss power is maximal. We found that the maximum specific loss power was determined by the Brown magnetic relaxation processes, and the maximum power obtained was significantly higher than that which would be obtained by the Néel relaxation processes under the same conditions. Moreover, increasing the amplitude of the magnetic field led to a significant decrease in the optimal diameter at which the maximum specific loss power is obtained (e.g., for 500 kHz frequency the optimal diameter decreased from 13.6 nm to 9.8 nm when the field increased from 10 kA/m to 50 kA/m), constituting a major advantage in magnetic hyperthermia for its optimization, in contrast to the known results in the absence of cyclodextrins from the surface of immobilized nanoparticles of CoFe2O4, where the optimal diameter remained practically unchanged at ~6.2 nm. [ABSTRACT FROM AUTHOR]

Persulfate-based advanced oxidation processes have been widely considered efficient remediation methods, and ferrite is a satisfactory activator of persulfate (PS) for the removal of environmental pollutants. Herein, cobalt ferrite nanoparticles (nano-CoFe2O4) were synthesized by the co-precipitation method and used to activate peroxymonosulfate (PMS) for the degradation of Congo red (CR) in aqueous solution. The results of characterization analysis showed that these nanoparticles exhibit an average crystallite size in the range of 13.96-25.17 nm, with a spherical structure, rich functional groups on their surfaces, and excellent magnetic and thermal stability. Furthermore, degradation experiments were designed to investigate the effects of a single factor, including the initial CR concentration, PMS concentration, catalyst dosage, initial pH and coexisting ions. The corresponding removal behaviour is in good agreement with the pseudo-first-order dynamics model. In addition, in the nano-CoFe2O4/PMS system, according to the identification results of reactive oxygen species, superoxide radical (•O2-) and singlet oxygen radical (1O2) species were the major active species that degraded CR, and the mechanism of PMS activation was comprehensively proposed. Meanwhile, after nano-CoFe2O4 was used five times continuously, the CR removal efficiency in the nano-CoFe2O4/PMS system decreased by only 7%, indicating that the prepared catalyst has excellent reusability. Therefore, the nano-CoFe2O4 synthesized in this research represents a novel, economical and efficient activator of PMS for the degradation of organic dyes in industrial wastewater. [ABSTRACT FROM AUTHOR]

We discuss the atomic structure of cobalt ferrite nanoparticles doped with Mn via an analysis based on combining atomic pair distribution functions with high energy X-ray diffraction and high-resolution transmission electron microscopy measurements. Cobalt ferrite nanoparticles are promising materials for metal–air battery applications. Cobalt ferrites, however, generally show poor electronic conductivity at ambient temperatures, which limits their bifunctional catalytic performance in oxygen electrocatalysis. Our study reveals how the introduction of Mn ions promotes the conductivity of the cobalt ferrite electrode.

Bioactive materials in combination with antibiotics have been widely developed for the treatment of bone infection. Thus, this work aims to characterize six biomaterials formulated with different concentrations of hydroxyapatite and cobalt ferrite nanoparticles, in addition to the antibiotic ciprofloxacin, using X-ray diffraction (XRD), scanning electron microscopy (SEM), and the antibiotic diffusion test on agar. Furthermore, in vivo biocompatibility and the reabsorption process of these materials were analyzed. XRD showed that both hydroxyapatite and cobalt ferrite present high crystallinity. The photomicrographs obtained by SEM revealed that composites have a complex surface, evidenced by the irregular arrangement of the hydroxyapatite and cobalt ferrite granules, besides demonstrating the interaction between their components. The antibiotic-diffusion test showed that all biomaterials produced an inhibition halo in Staphylococcus aureus cultures. For the biocompatibility study, composites were surgically implanted in the dorsal region of rabbits. At 15, 30, 70, and 100 days, biopsies of the implanted regions were performed. The biomaterials were easily identified during histological analysis and no significant inflammatory process, nor histological signs of toxicity or rejection by the adjacent tissue were observed. We can conclude that the biomaterials analyzed are biocompatible, degradable, and effective in inhibiting the in vitro growth of Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

In this work, The production of graphene nanoribbon (GNR)/CoFe2O4 nanocomposite is described using a simple, cost-effective, and innovative technique. X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were proved that graphene nanoribbons and GNR-CoFe2O4 nanocomposite were successfully synthesized. The designed nano-sensor was employed for the determination of vanillin using a carbon paste electrode (CPE) modified with graphene nanoribbons-CoFe2O4 nanocomposite and 1-methyl-3-butylimidazolium bromide (ionic liquid (IL)). The electrochemical behavior modified electrode for vanillin detection exhibited excellent electrocatalytic activity with a high peak current. Under the optimized conditions, the calibration curve offered linearity over a wide range of 0.01–500 µM, with a limit of detection of 5.2 nM. The fabricated nanosensor was successfully utilized for determination of vanillin in commercial real food samples with an outstanding recovery. [ABSTRACT FROM AUTHOR]

CoFe _2 O _4 , CoBi _0.1 Fe _1.9 O _4 , CoLa _0.1 Fe _1.9 O _4 , and CoAl _0.1 Fe _1.9 O _4 nanoparticles were successfully synthesized by the coprecipitation method. After annealing at 700 °C for 5 h, the x-ray Diffractometer results confirm that a single phase of cobalt ferrite-based nanoparticles is obtained, which is suitable for ICDD 22-1086. The addition of Bi ^3+ , La ^3+ and Al ^3+ ions to the cobalt ferrite nanoparticles modified the crystallite size and lattice constant. Trivalent metal cation substitution tunes the crystallite size which has also been confirmed by measuring the grains with Scanning Electron Microscope images. In the Far Transform Infra-Red curve, the addition of metal ions (Bi ^3+ , La ^3+ , and Al ^3+ ) to cobalt ferrite nanoparticles resulted in absorption peaks at the tetrahedral and octahedral sites without any additional absorption peaks. The VSM results showed that saturation magnetization decreased drastically in the presence of trivalent non-magnetic cations, which confirms the replacement of Fe ^3+ by trivalent non-magnetic cations. The kOe order of the coercive field was obtained in this experiment. The largest coercive field of the cobalt ferrite nanoparticles was obtained with the addition of La ^3+ ions, i.e. 3.67 kOe suggest to support both Jahn-Teller effect and strain-induced magnetism.

Fe oxide magnetic nanoparticles (MNPs) in general and cobalt ferrite nanoparticles in particular have immense potential for applications in catalysis, medicine, information and energy storage, etc. MNPs feature interesting physical and chemical properties, different to those of corresponding bulk materials. The magnetic anisotropy constant of almost spherical CoFe2O4 MNPs is much higher than that of magnetite (Fe3O4) MNPs of similar geometrical parameters due to the magnetocrystalline contribution. CoFe2O4 shows significant magnetization at saturation, high coercive field and Curie temperature, and good chemical and magnetic stability, being therefore preferable to the most usual Fe3O4 MNPs. A surfactant-assisted synthetic route was employed to synthesize Fe oxide and in particular cobalt ferrite MNPs over a wide pH range (3–13), endeavor which allowed analysis of transient and parasitic phase identified in acidic reaction conditions. [ABSTRACT FROM AUTHOR]

In this study, we have investigated structural and magnetic characteristics of cobalt ferrite (CoFe2O4) nanocrystalline powders prepared with different chelating agents/gelation promoters. Cobalt ferrite crystalline powders were prepared through sol-gel method with three gelation promoters namely, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG). After initial characterization of the samples by X-ray diffraction, TEM, TG-DSC techniques, FTIR, and Mössbauer spectroscopy techniques, the magnetic properties of the samples were measured using VSM. The analysis of the results clearly indicated that the cobalt ferrite samples prepared with chelating agent of lower molecular weight (PEG) have exhibited high saturation magnetization. The reasons for such higher magnetization have been identified and discussed. TEM images of CoFe2O4 nanoparticles are synthesized using sol-gel method with different chelating agents/gelation promoters namely PVA, PVP and PEG. [ABSTRACT FROM AUTHOR]

We synthesized CoFe2O4 nanoparticles using heating in various times by simple microwave method at power about 600W. Water, ethylene glycol and their combination were used as solvent. X-ray diffraction pattern(XRD) analysis was performed for evaluation of structural characterization of samples. We also used scanning electron microscopy (SEM) to evaluate the effects of various parameters of heating time and solvent type on mean grain size and nanostructure of the samples. Our results showed that with changing of these parameters, we can control the nanostructure and grain size of prepared samples. In addition, we produced polymeric nanocomposite of PVA/CoFe2O4 using poly vinyl alcohol films. The thermal stability of it in comparison to PVA polymer was assessed by thermal gravimetric analysis (TGA). Also the nanostructures of polymer nanocomposite were analyzed by SEM. To evaluate the magnetic parameters of samples, vibrating sample magnetometer (VSM) analysis were done. Also the spectrum of synthesized nanoparticles and polymer nanocomposite were drawn by FT-IR. Our results confirmed that the nanostructures, magnetic behavior and thermal stability of the prepared nanocomposite are acceptable for needed applications. Key Words: Cobalt ferrite nanoparticles, Magnetic behavior, Nanostructure, Polymer nanocomposite, Thermal stability

Cobalt ferrite (CoFe 2 O 4) nanoparticles were synthesized through the citrate precursor route. The XRD pattern confirmed the formation of a homogeneous single-phase spinel structure with an Fd3m space group. No impurities or unreacted constituents in the sample were observed. Analysis of the most prominent (311) peak of the XRD pattern revealed the crystallite size to be ~39 nm with lattice constant and interplanar spacing as ~8.374 Å and ~2.525 Å, respectively. Other key structural parameters, such as dislocation density, strain, X-ray density, and hopping lengths, were also obtained from XRD data. Structural parameters were refined by applying the full pattern fitting of the Rietveld method using the Pseudo-Voigt function. High-resolution images obtained from SEM and TEM confirmed the morphological characteristics and crystallite size of the CoFe 2 O 4 nanoparticles. The hysteresis loop recorded over the applied external magnetizing field of −10 kOe to +10 kOe revealed a specific saturation magnetization, specific remanent magnetization, and coercivity value of ~64 emu/g, ~24 emu/g, and ~565 Oe, respectively. A remanence ratio ~0.374 signified magnetostatic interaction between CoFe 2 O 4 nanoparticles and confirmed their multi-domain structure and soft magnetic nature. Investigations were carried out to obtain the variations in complex dielectric permittivity, complex magnetic permeability, dielectric and magnetic loss tangents, AC conductivity, and quality factor in 1–6 GHz frequency range. The CoFe 2 O 4 nanoparticles exhibited low dielectric and magnetic loss tangents of 10−2 and 10−3 order, along with moderate values of relative permittivity and refractive index, i.e., 4.801 and 2.3, respectively. The sustained magneto-dielectric behaviour and low-loss characteristics suggest that CoFe 2 O 4 nanoparticles can be suitably dispersed in a dielectric matrix and used to develop efficient substrate material for improved telemetry, telecommunications and radar systems of aerospace systems operating over the 1–6 GHz frequency range. [ABSTRACT FROM AUTHOR]

Cobalt ferrite nanoparticles were synthesized by the citric acid-assisted hydrothermal method with the citric acid to metal ion molar ratio (C/M) 0.5, 1, and 1.5. Nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM) techniques. The coarse cobalt ferrite particles are synthesized along with hematite impurities when using the routine hydrothermal method. However, the results showed that single-phase and uniform cobalt ferrite nanoparticles were formed in the presence of citric acid. The obtained results also revealed that by changing the C/M ratio from 0.5 to 1 and 1.5, the mean crystallite size and maximum magnetization were changed from 7.8, 4.7, and 7.3 nm and 50.3, 40, and 48.2 emu/g, respectively. Therefore, citrate acid concentration plays a significant role in the final properties of synthesized particles. Moreover, this parameter is a powerful tool for regulating the properties of nanoparticles. In addition, in this study, a mechanism for synthesis producer and role of the chelating agent concentration, based on the stability of the formed complexes during the synthesis process and its effect on the nucleation temperature, has been presented. [ABSTRACT FROM AUTHOR]

A wet chemical method was used to synthesize the cobalt ferrite nanoparticles (CFN) and further calcined at 1000°C. The effect of calcination onto the structure, morphology and crystallinity of the synthesized material was examined by different characterization techniques such as field-emission scanning electron microscopy (FE-SEM), Fourier transform infra-red (FTIR), thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD). The results identified that after calcination at 1000°C, the cobalt ferrite nanoparticles become more stable, bigger in crystallite size, lattice constant and greater cation distribution between octahedral and tetrahedral sites as compared to uncalcined parent CFN. Furthermore, the magnetic properties of both parent and calcined cobalt ferrite nanoparticles were also determined by the vibrating-sample magnetometer. The results declared that the saturation magnetization increased with the increased calcination while the converse is true for coercivity. The reason behind the decrease of coercivity is the pining effect at gain boundary. The hysteresis loop slowly levels as the temperature moves toward Curie temperature. [ABSTRACT FROM AUTHOR]

In this paper, we present a theoretical study on the maximum specific loss power in the admissible biological limit (PsM)l for CoFe2O4 ferrimagnetic nanoparticles, as a possible candidate in alternative and non-invasive cancer therapy by superparamagnetic hyperthermia. The heating time of the nanoparticles (Δto) at the optimum temperature of approx. 43 °C for the efficient destruction of tumor cells in a short period of time, was also studied. We found the maximum specific loss power PsM (as a result of superparamegnetic relaxation in CoFe2O4 nanoparticles) for very small diameters of the nanoparticles (Do), situated in the range of 5.88–6.67 nm, and with the limit frequencies (fl) in the very wide range of values of 83–1000 kHz, respectively. Additionally, the optimal heating temperature (To) of 43 °C was obtained for a very wide range of values of the magnetic field H, of 5–60 kA/m, and the corresponding optimal heating times (Δto) were found in very short time intervals in the range of ~0.3–44 s, depending on the volume packing fraction (ε) of the nanoparticles. The obtained results, as well as the very wide range of values for the amplitude H and the frequency f of the external alternating magnetic field for which superparamagnetic hyperthermia can be obtained, which are great practical benefits in the case of hyperthermia, demonstrate that CoFe2O4 nanoparticles can be successfully used in the therapy of cancer by superaparamagnetic hyperthermia. In addition, the very small size of magnetic nanoparticles (only a few nm) will lead to two major benefits in cancer therapy via superparamagnetic hyperthermia, namely: (i) the possibility of intracellular therapy which is much more effective due to the ability to destroy tumor cells from within and (ii) the reduced cell toxicity. [ABSTRACT FROM AUTHOR]

Nanoparticles of CoGdxFe2-xO4 (x = 0%, 25%, 50%) synthesized via sol-gel auto combustion technique and encapsulated within a polymer (Eudragit E100) shell containing curcumin by single emulsion solvent evaporation technique were formulated in this study. Testing of synthesized nanoparticles was carried out by using different characterization techniques, to investigate composition, crystallinity, size, morphology, surface charge, functional groups and magnetic properties of the samples. The increased hydrophilicity resulted in sustained drug release of 90.6% and 95% for E1(CoGd0.25Fe1.75O4) and E2(CoGd0.50Fe1.5O4), respectively, over a time span of 24 h. The relaxivities of the best-chosen samples were measured by using a 3T magnetic resonance imaging (MRI) machine, and a high r2/r1 ratio of 43.64 and 23.34 for composition E1(CoGd0.25Fe1.75O4) and E2(CoGd0.50Fe1.5O4) suggests their ability to work as a better T2 contrast agent. Thus, these novel synthesized nanostructures cannot only enable MRI diagnosis but also targeted drug delivery. [ABSTRACT FROM AUTHOR]

Goals of the investigation: This work aimed to evaluate the neuroprotective effects of zinc oxide (ZnO) nanoparticles in an experimental mouse model of rotenone-induced PD and investigate the therapeutic effects of ZnO, cobalt ferrite nanoparticles, and their combination. Methods: The levels of dopamine, norepinephrine, epinephrine, and serotonin were assessed using ELISA in the control and experimental model of PD mice. The dopa-decarboxylase expression level was assayed by real-time PCR. The expression level of tyrosine hydroxylase (TH) was assessed by western blot analysis. Results: Our data showed that levels of dopamine decreased in PD mice compared to normal. ZnO NP increased dopamine levels in normal and PD mice (37.5% and 29.5%; respectively, compared to untreated mice). However, ZnO NP did not cause any change in norepinephrine and epinephrine levels either in normal or in PD mice. Levels of serotonin decreased by 64.0%, and 51.1% in PD mice treated with cobalt ferrite and dual ZnO- cobalt ferrite NPs; respectively, when compared to PD untreated mice. The mRNA levels of dopa-decarboxylase increased in both normal and PD mice treated with ZnO NP. Its level decreased when using cobalt ferrite NP and the dual ZnO-cobalt ferrite NP when compared to untreated PD mice. A significant decrease in TH expression by 0.25, 0.68, and 0.62 folds was observed in normal mice treated with ZnO, cobalt ferrite, and the dual ZnO-cobalt ferrite NP as compared to normal untreated mice. In PD mice, ZnO administration caused a non-significant 0.15-fold decrease in TH levels while both cobalt ferrite and the dual ZnO-cobalt ferrite NP administration caused a significant 0.3 and 0.4-fold decrease respectively when compared to untreated PD mice. Principal conclusion : This study reveals that ZnO NPs may be utilized as a potential intervention to elevate dopamine levels to aid in PD treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

To develop a biocompatible cobalt ferrite (CF-NP) nanodrug formulation using oleic acid and poly (d,l-lactide-co-glycolic) acid (PLGA) for the delivery of docetaxel (DTX) specifically to breast cancer cells. The CF-NP were synthesised by hydrothermal method and conjugated with DTX in a PLGA matrix and were systematically characterised using XRD, FE-SEM, TEM, DLS, FTIR, TGA, SQUID etc. The drug loading, in vitro drug release, cellular uptake, cytotoxicity were evaluated and haemolytic effect was studied. The CF-NP showed good crystallinity with an average particle size of 21 nm and ferromagnetic nature. The DTX-loaded CF-NP (DCF-NP) showed 8.4% (w/w) drug loading with 81.8% loading efficiency with a sustained DTX release over time. An effective internalisation and anti-proliferative efficiency was observed in MCF-7 and MDA-MB-231 breast cancer cells and negligible haemolytic effect. The DCF-NP can have the potential for the effective delivery of DTX for breast cancer treatment. [ABSTRACT FROM AUTHOR]

In this study, the hyperthermia efficiency of CoFe 2 O 4 nanoparticles (CFNPs) was enhanced by narrowing their size distribution and increasing their magnetic moment. The CFNPs were synthesized using the solvothermal reflux method. The NPs were crystallized in the face-centered cubic spinel structure (lattice parameter of 8.373 Å) and had a particle size of ~10 nm, as revealed by the X-ray diffraction and transmission electron microscopy (TEM) results, respectively. The high-resolution TEM images of the NPs revealed their single crystal nature. The infrared absorption bands above 700 cm−1 confirmed the formation of octahedral and tetrahedral ligands on the surface of the NPs. The thermal analysis profiles of the synthesized NPs showed that the surface ligands decomposed at approximately 360 °C. The nanocolloids prepared using the NPs showed stable dispersion with a zeta potential of −17.7 mV. The X-ray photoelectron spectroscopy results revealed the presence of Co2+, Fe3+, and O2− in the NPs. The NPs existed in the superparamagnetic state with a maximum mass magnetization of 71 emu g−1, which is close to the theoretical value. The magnetic hyperthermia property of the NPs was investigated by determining their specific heat generation rate (SHGR) under biocompatible alternate magnetic field parameters. The NPs were capable of heating 185.32 W g−1. This value is greater than the SHGR reported previously for CFNPs synthesized by other methods. [ABSTRACT FROM AUTHOR]

Objective: this study evaluate the interaction of Cobalt Ferrite (CoFe2O4) and Nickel-Zinc Iron Oxide (Ni0.5Zn0.5Fe2O4) nanoparticles with human erythrocytes in relation to the hemolytic activity and the effect of the above nanoparticles on human plasma albumin of patients with β - thalassemia major compared to healthy subjects. Design and Methods: the study include 40 β - thalassemia major patients and 20 apparently healthy subjects. The hemolysis % assay and in vitro anti-inflammatory effect of the above nanoparticles were used. Results: The results indicated that Co ferrite nanoparticles increases the fragility (the hemolysis % was higher) of the erythrocytes more readily in the case of β - thalassemia patients compared to healthy subjects and the Ni-Zn ferrite nanoparticles increase the fragility of healthy subjects erythrocytes while in the case of thalassemia patients the hemolysis % were decrease with increasing the concentration of nanoparticles. The anti-inflammatory effect of the above nanoparticles was evaluated using the inhibition of denaturation method for human plasma albumin, the results have shown significant in-vitro anti-inflammatory effect of Co ferrite nanoparticles on plasma albumin but lower than the effect of Ni-Zn ferrite nanoparticles. Conclusions: Changes in the morphological features of erythrocytes were noticed due to the interaction of the above nanoparticles. Stability of erythrocytes was observed at lower concentration of these nanoparticles and the possible mechanisms of interaction have been described. [ABSTRACT FROM AUTHOR]

Magnetic paper sheets were prepared from bleached sugarcane bagasse fibers and cobalt ferrite nanoparticles by lumen loading method. Sugarcane bagasse is an important fibrous raw material widely used worldwide for papermaking, whereas cobalt ferrite nanoparticles is an appropriate material for fibers modification given their magnetic properties. Cobalt ferrite nanoparticles were synthetized by coprecipitation method and coated with silica by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) molecules. Then, silica coated magnetic nanoparticles were functionalized with polyethylenimine (PEI), as retention aid, by electrostatic bonding. It was observed that the loading degree of magnetic fibers depends on nanoparticles concentration and PEI dosage, which was determined by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) shows the deposition of coated nanoparticles on the surface and into macropores of fibers. All samples exhibited ferromagnetic behavior. The coercivity values of magnetic fibers are higher than 0.2 kOe. This indicates that these fibers could be used to produce paper for magnetic recording purposes. Magnetic papers with 10 and 20% of modified fibers were manufactured. Brightness and tensile index of papers were decreased with the rise of loading degree. CIEL*a*b analysis shows the color differences between unmodified and modified papers. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles (MNPs) are widely considered for cancer treatment, in particular for magnetic hyperthermia (MHT). Thereby, MNPs are still being optimized for lowest possible toxicity on organisms while the magnetic properties are matched for best heating capabilities. In this study, the biocompatibility of 12 nm cobalt ferrite MNPs, functionalized with citrate ions, in different dosages on mice and rats of both sexes was investigated for 30 days after intraperitoneal injection. The animals’ weight, behavior, and blood cells changes, as well as blood biochemical parameters are correlated to histological examination of organs revealing that cobalt ferrite MNPs do not have toxic effects at concentrations close to those used previously for efficient MHT. Moreover, these MNPs demonstrated high specific loss power (SLP) of about 400 W g−1. Importantly the MNPs retained their magnetic properties inside tumor tissue after intratumoral administration for several MHT cycles within three days. Thus, cobalt ferrite MNPs represent a perspective platform for tumor therapy by MHT due to their ability to provide effective heating without exerting a toxic effect on the organism. This opens up new avenues for smaller MNPs sizes while their heating efficiency is maintained.

Controlling the morphology and magnetic properties of CoFe2O4 nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe2O4 nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe2O4 nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe2O4 nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe2O4 nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe2O4 nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe2O4 nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe2O4 nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe2O4 magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.

In this paper, we present a theoretical study on the maximum specific loss power in the admissible biological limit (PsM)l for CoFe2O4 ferrimagnetic nanoparticles, as a possible candidate in alternative and non-invasive cancer therapy by superparamagnetic hyperthermia. The heating time of the nanoparticles (Δto) at the optimum temperature of approx. 43 °C for the efficient destruction of tumor cells in a short period of time, was also studied. We found the maximum specific loss power PsM (as a result of superparamegnetic relaxation in CoFe2O4 nanoparticles) for very small diameters of the nanoparticles (Do), situated in the range of 5.88–6.67 nm, and with the limit frequencies (fl) in the very wide range of values of 83–1000 kHz, respectively. Additionally, the optimal heating temperature (To) of 43 °C was obtained for a very wide range of values of the magnetic field H, of 5–60 kA/m, and the corresponding optimal heating times (Δto) were found in very short time intervals in the range of ~0.3–44 s, depending on the volume packing fraction (ε) of the nanoparticles. The obtained results, as well as the very wide range of values for the amplitude H and the frequency f of the external alternating magnetic field for which superparamagnetic hyperthermia can be obtained, which are great practical benefits in the case of hyperthermia, demonstrate that CoFe2O4 nanoparticles can be successfully used in the therapy of cancer by superaparamagnetic hyperthermia. In addition, the very small size of magnetic nanoparticles (only a few nm) will lead to two major benefits in cancer therapy via superparamagnetic hyperthermia, namely: (i) the possibility of intracellular therapy which is much more effective due to the ability to destroy tumor cells from within and (ii) the reduced cell toxicity.

High coercive single-domain CoFe2O4 nanoparticles with the minimal average size (7.6–12.8 nm) were synthesized by polyethylene glycol (PEG) assisted sol–gel method and subsequent annealing at different temperatures. The prepared samples were characterized by XRD, TEM, TG-DSC, and FTIR techniques. The XRD and TEM studies indicated the size and shape of the particles are highly dependent on annealing temperature. Magnetic properties of the developed cobalt ferrite nanoparticles were found to be dependent on their size and shape. The particles annealed at lower temperatures (about 400 °C) are found to be near spherical in shape and as the annealing temperature is increased from 400 to 800 °C, the shape of the particles is observed to be transformed from spherical to octahedron through intermediate cubic shape. Magnetic parameters viz., saturation magnetization (Ms) and remnant magnetization (Mr) exhibited a study increase with increase of the particle size. The coercive field, Hc exhibited a non-monotonic behavior with distinct maximum at about 700 °C and suggested the transition from single-domain to multi-domain state. The magneto-crystalline anisotropy constant, K, determined from Stoner–Wohlfarth relation, exhibited the maximum value, 10.74 × 106 erg/cm3 for the samples annealed at 800 °C. In addition, the magnitude of (BH)max (which is considered as the efficiency of cobalt ferrite nanoparticles for using as permanent magnets) exhibited the maximum value (1.04 × 106 GOe). Such higher values of these two parameters suggest the possible applications of the studied material in magnetic recording, high density digital recording disks and in magnetic sensors. [ABSTRACT FROM AUTHOR]

In this work, the synthesis and characterization of cobalt ferrite nanoparticles (CoFe2O4 NPs) were carried out. The characterization studies confirmed that the synthesized particles were determined to be magnetic CoFe2O4 NPs in nanoscale and cubic spinel structure. The Brunauer-Emmett-Teller specific surface area of mesoporous CoFe2O4 NPs was determined to be 145.03 m2/g. The photo Fenton-like degradation ability of CoFe2O4 NPs was also evaluated and the results demonstrated that the synergistic effect of combining of Co and Fe2O4 enabled CoFe2O4 NPs to become the promising photo Fenton-like catalyst for degradation of methylene blue (MB) from aqueous solutions. At the optimum experimental conditions (3.0 of initial pH, 25 mM of H2O2 concentration, 50 mg/L of initial dye concentration, and 0.25 g/L of catalyst concentration), 18.29% chemical oxygen demand removal and 99.75% color removal were achieved after the photo Fenton-like degradation of MB in the presence of CoFe2O4 NPs heterogeneous catalyst with near-UV radiation. [ABSTRACT FROM AUTHOR]

We discuss the calcination temperature dependence of the structural and magnetic properties of co-precipitated cobalt ferrite. Calcination process was performed under atmospheric condition without inert gas. High-purity cobalt ferrite nanoparticles are obtained experimentally. The size of the crystallites increases with the increase of the calcination temperature. Furthermore, the XRD analysis result show that cation redistribution occurs with the increase of the calcination temperature. The SEM result show that the structural organization of these particles changes from separate nanoparticles to the formation of compact granules with increasing calcination temperature. As a result, the saturation magnetization increases with the calcination temperature, reaching up to 62.30 emu/g. It was found that the cation distribution for both tetrahedral and octahedral sites affected by the calcination temperature. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CoFe 2 O 4) nanoparticles were prepared by chemical co-precipitation route at low temperature (70 °C). X-ray diffraction pattern confirms the cubic inverse spinel structure with an average crystallite size of ∼14 nm. Transmission electron microscopy exhibits a narrow distribution of particle size with an average particle size of 15 nm. The synthesized nanoparticles exhibited a saturation magnetization of 23.2 e m u / g and 33.6 e m u / g at 300 K and 20 K respectively. The randomly oriented spin layer thickness of 1.74 nm calculated at room temperature reduces the value of magnetization in as-synthesized nanoparticles. Exponential decay was observed in coercivity (H c) and remanence magnetization (M r) with the increase in temperature from 20 K to 300 K. Blocking temperature of 250 K is found from d (Z F C − F C) d t versus T curve. The plot of H H T versus T revealed the superparamagnetic behavior and exhibited largest superparamagnetic moment at 300 K. The effective anisotropy constant and surface anisotropy constant were calculated to be 6.00 × 104 J/m3 and 1.08 × 10−4 J/m2 respectively at blocking temperature. • Reduction in M s values with increasing temperature is attributed to the presence of non- magnetic surface layer and spin canting. • As synthesized single domain magnetic nanoparticles exhibited large magnetic moment per particle. • Dependence of superparamagnetic moment ((μ s p)) with temperature (T) and applied magnetic field (H) has been analysed systematically. • From vs. T graph, temperature ranges were measured for which as synthesized CoFe2O4 exhibits superparamagnetic behavior. • At 250 K and 300 K as synthesized CoFe2O4 nanoparticle exhibits superparamagnetic behavior with highest superparamagnetic moment 1.54 × 104 μB at T = 300 K. • The magnetic properties of cobalt ferrite nanoparticles synthesized in present work can be used as base ferrite materials environmental and biomedical applications. [ABSTRACT FROM AUTHOR]