Showed Saturation Magnetization Research Articles

Effect of particle size and composition on local magnetic hyperthermia of chitosan-Mg1-xCoxFe2O4 nanohybrid.

In this study, Mg1-xCoxFe2O4 (0≤x ≤ 1 with ∆x = 0.1) or MCFO nanoparticles were synthesized using a chemical co-precipitation method and annealed at 200, 400, 600, and 800°C respectively to investigate the structural properties of the materials by X-ray diffractometer (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Controlled annealing increased particle size for each value of x. The aim was to investigate how specific loss power (SLP) and maximum temperature (Tmax) during local magnetic hyperthermia were affected by structural alterations associated with particle size and composition. The lattice parameter, X-ray density, ionic radius, hopping length, bond length, cation-cation distance, and cation-anion distance increase with an increase in Co2+ content. Raman and FTIR spectroscopy reveal changes in cation distribution with Co2+ content and particle size. Magnetic properties measured by the physical property measurement system (PPMS) showed saturation magnetization (Ms), coercivity (Hc), remanent magnetization (Mr/Ms), and anisotropy constant (K1) of the Mg1-xCoxFe2O4 nanoparticles increase with Co2+ content and particle size. When exposed to an rf magnetic field, the nanohybrids experienced an increase in both the SLP (specific loss power) and Tmax (maximum temperature) as the particle size initially increased. However, these values reached their peak at critical particle size and subsequently decreased. This occurs since a modest increase in anisotropy, resulting from the presence of Co2+ and larger particle size, facilitates Néel and Brownian relaxation. However, for high anisotropy values and particle size, the Néel and Brownian relaxations are hindered, leading to the emergence of a critical size. The critical size increases as the Co2+ content decreases, but it decreases as the Co2+ content increases, a consequence of higher anisotropy with the increase in Co2+. Additionally, it is noteworthy that the maximum temperature (Tmax) rises as the concentration of nanohybrids grows, but the specific loss power (SLP) decreases. An increased concentration of chitosan-MCFO nanohybrids inhibits both the Néel and Brownian relaxation processes, reducing specific loss power.

Structural, magnetic, optical, and antibacterial properties of Mn1-xNixFe2O4 nanoparticles

Herein, we report the synthesis of Mn1-xNixFe2O4 (MNFO) nanoparticles (NPs) with lime peel and capsicum coating for different compositions (x = 0.0–0.4) by chemical co-precipitation method tested for antibacterial properties. The coated sample, Mn0.6Ni0.4Fe2O4 NPs has exhibited excellent antibacterial activity against gram positive and negative species compared to uncoated ones. Significantly, lime peel coated samples have exhibited more antibacterial effect as compared to capsaicin coated at x = 0.4. The crystallite size of the sample analysed via X-ray diffraction (XRD) is in nano regime, 7–10 nm. Results show considerably low strain for all samples except a peak value for composition at x = 0.1; which can be ascribed to the cation distribution and different ionic radii of the bivalent metal ions. Fourier transform infrared spectroscopy (FTIR) confirms presence of functional groups. The ultraviolet visible (UV–Vis) spectra reveal indirect band gap of 2–2.5 eV. The field emission scanning electron microscopy (FESEM) analysis shows nano cubical structure. The energy dispersive x-ray (EDX) spectroscopy confirms the presence of elements (Mn, Ni, Fe, and O) in the sample. The magnetic properties have investigated using vibrating sample magnetometer (VSM), shows saturation magnetization and remnant magnetization decreases with increasing Ni content. The low values of saturation magnetization and coercive force is indicative of formation of soft ferrite with super paramagnetic in nature.

Crystal Structure, Optical and Magnetic Properties of Green-Synthesized NiZnFe<sub>2</sub>O<sub>4</sub>/SiO<sub>2</sub> for Degradation of Methylene Blue

NiZnFe2O4/SiO2 was successfully synthesized by green-synthesis method using moringa oleifera with various concentrations of 0%, 5%, 10%, 15%, 20%, 30% and 50%. X-Ray diffraction spectra showed that the crystal structure of NiZnFe2O4/SiO2 has a mixed cubic spinel structure. Fourier-transform infrared spectra indicated the C-H functional group at 2374-2378 cm-1 which identified that green synthesis has been successfully carried out, Si-O-Si (siloxane) at 1072-1100 cm-1 which was confirmed as NiZnFe2O4/SiO2 which allows modification silica was successfully encapsulated in NiZnFe2O4/SiO2 confirmed by the presence of Si-O-Si groups at 1065-1086 cm-1. The result of the vibrating sample magnetometer NiZnFe2O4/SiO2 showed saturation magnetization and coercivity was 9-18 emu/g and with at 44-50 Oe respectively, so it is detected as superparamagnetic. The UV-Vis absorbance spectrum of NiZnFe2O4/SiO2 for all concentrations was at 194 nm with a band gap of energy ranging from 3.14 to 3.34 eV which indicates good absorption. The Photocatalytic process with NiZnFe2O4/SiO2 using organic dye methylene blue was available to do up to 94%.

Effect of TiO<sub>2 </sub>on Photocatalytic Activity of NiZnFe<sub>2</sub>O<sub>4</sub>/TiO<sub>2</sub> Nanocrystalline for Methylene Blue Degradation

The photocatalytic activity of NiZnFe2O4/TiO2 core-shell gg nanocrystalline was carried out. The NiZnFe2O4/TiO2 core-shell was synthesized using co-precipitation method with various concentrations 1:0, 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction spectra pattern showed crystallite size at various concentrations 1:0, 1:1, and 1:3, which of 5.00 nm, 4.90 nm, and 10.81 nm, respectively. The morphology of NiZnFe2O4 nanocrystalline was characterized by transmission electron microscopy which confirmed that the sample undergoes agglomeration with not uniform particle shape. The average particle size of the nanocrystalline was 10.26 nm. Fourier transform infra-red showed functional groups such as Ti-O-Ti, M-Otetra, and M-Oocta at 1473.62, 563 - 586, and 401- 424 cm-1. In addition, the presence of Ti-O-Ti and M-O functional groups indicates NiZnFe2O4/TiO2 core-shell has been formed. The absorbance spectrum of the NiZnFe2O4/TiO2 core-shell has an energy band gap in the range of 2.1 – 3.3 eV. The results of the Vibrating sample magnetometer showed saturation magnetization and coercivity values ​​in the range of 12.4 – 22.9 emu/gr and 47 - 55 Oe, which were correlated as soft magnetic properties. NiZnFe2O4/TiO2 was successfully degraded Methylene Blue that reach 99.8% under UV light irradiation. The addition of TiO2 increases degradation, TiO2 acts as a trapping state that inhibits electron-hole recombination which can prolong the reaction time between free electrons and MB solution molecules. This study revealed the high potential of NiZnFe2O4/TiO2 core-shell nanocrystalline in photocatalytic application.

The study of structural, magnetic, and microwave absorbing properties of graphene/hexagonal ferrite for microwave absorber

This work reports the synthesis and characterization of Y-type Hexaferrite (Ba2Co2Fe12O22) and its composites with 20, 30, 40, and 50 wt% rGO. Ferrites were fabricated using the hydrothermal method and then sintered for 6 h at 1000 °C. The formation of Y-type hexaferrite (Ba2Co2Fe12O22) and Ferrites/rGO composites was confirmed using x-ray diffraction. Ferrite/rGO composites exhibited no diffraction peaks due to rGO, which may be due to staking disorders and uniformly dispersed graphene sheets. Scanning electron microscopy showed that graphene nanolayers are well-decorated with Y-type hexaferrite nanoparticles. FTIR spectra measured for Ba2Co2Fe12O22, rGO, and Ba2Co2Fe12O22/rGO nanocomposites revealed the presence of relevant functional chemical bonds. The dielectric properties studied between 1MHz-3GHz frequency range showed that composites of Ba2Co2Fe12O22/rGO perform better than pure ferrite. Diffuse reflectance spectroscopy was applied to determine the band gap, and rGO/Ferrites composites exhibited a band gap in the range of 4.4–4.6 eV. Vibrating sample magnetometer (VSM) measurements showed saturation magnetization of 26.2 emu g−1 in pure hexaferrite, which significantly lowered with rGO content in the composites. From enhanced absorption and reflection parameters of dielectric properties and magnetic loss that originate from the synergetic effect of rGO and Y-type hexaferrite (Ba2Co2Fe12O22), this study suggests lightweight, flexible, and efficient EMI shielding composites.

Room-Temperature, Nanoscale Multiferroic Pb(Fe0.5Ta0.5)1−x(Zr0.53Ti0.47)xO3 (x = 0.2, 0.3) Thin Films Grown via the Pulsed Laser Deposition Technique

Multiferroic materials capable of robust magnetoelectric coupling at room temperature are currently being explored for their possible multifunctional device applications. Highly (100)-oriented Pb(Fe0.5Ta0.5)x(Zr0.53Ti0.47)1−x (PZTFTx) thin films (x = 0.2 and 0.3) with a thickness of about 300 nm were grown on La0.67Sr0.33CoO3 (LSCO)-buffered MgO 100-oriented substrates via the pulsed laser deposition method. An analysis of their X-ray diffraction patterns suggests the stabilization of the orthorhombic phase in the thin films at room temperature. Dielectric spectroscopic measurements of the metal–insulator–metal (Pt/PZTFTx/LSCO) thin-film capacitors as a function of temperature revealed a diffuse ferroelectric-to-paraelectric phase transition around Tm ~520 and 560 K for the x = 0.2 and 0.3 thin films, respectively. Well-saturated electrical hysteresis loops with large remanent (Pr) and saturation (Ps) polarizations were observed in these capacitors, which indicates the establishment of intrinsic ferroelectric ordering in the thin films at room temperature. These thin films retained ferromagnetic/ferrimagnetic ordering up to 300 K and showed saturation magnetization values of 8.3 (x = 0.2) and 6.1 (x = 0.3) emu/cm3 at room temperature. The magnetoelectric coupling constants of 2040 mV/cmOe (x = 0.2) and 850 mV/cmOe (x = 0.3), respectively, were obtained at an in-plane bias field at room temperature. The present study demonstrates that PZTFTx thin films are multiferroic at room temperature with large magnetoelectric couplings, and these materials may be suitable for use in magnetic sensors and spintronic device applications.

Nickel‐asparagine complex fixed on a magnetic substrate as a precursor for preparing substituted acridines

In this work, an efficient, novel, retrievable, and magnetic heterogeneous nanocatalyst, Fe3O4@CPTMS@Asp@Ni was successfully fabricated using Fe3O4 nanoparticles as the core that were coated with surfactant and 3‐chloropropyltrimethoxysilan and deposited asparagine and nickel metal that can be used in multicomponent reactions for the synthesis of acridines derivatives with high yield in short reaction times. The virtue of obtained nanocatalyst was identified using transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction analysis, energy dispersive X‐ray, Brunauer–Emmett–Teller, vibrating sample magnetometry, Raman, and thermogravimetric analysis. The X‐ray diffraction analysis studies demonstrate that the average crystallite sizes of the prepared nanocatalyst are estimated to be about 45.4 nm. Also, the vibrating sample magnetometry measurement shows saturation magnetization values (Ms) of 7 emu/g for Fe3O4@CPTMS@Asp@Ni nanocatalyst. Also, after the synthesis steps, the application of the prepared nanocatalyst in the preparation of acridine‐1,8(2H,5H)‐diones has been investigated. Then to evaluate and assess the efficiency of the nanocatalyst as mentioned above, and its effect on the synthesis of divergent acridines via a one‐pot, three‐component condensation reaction of cyclic 1,3‐dione, aryl glyoxal, with ammonium acetate in the water as green solvent was studied. Also, when investigating the reusability of this catalyst, it was observed that Fe3O4@CPTMS@Asp@Ni nanocatalyst could be reused at least five times without losing its efficiency. High efficiency, outstanding yields in quick intervals, easy separation using a magnetic field, and possessing reusability are significant benefits of the attained nanocatalyst.

Magnetic Nanoclusters Stabilized with Poly[3,4-Dihydroxybenzhydrazide] as Efficient Therapeutic Agents for Cancer Cells Destruction.

Magnetic structures exhibiting large magnetic moments are sought after in theranostic approaches that combine magnetic hyperthermia treatment (MH) and diagnostic magnetic resonance imaging in oncology, since they offer an enhanced magnetic response to an external magnetic field. We report on the synthesized production of a core-shell magnetic structure using two types of magnetite nanoclusters (MNC) based on a magnetite core and polymer shell. This was achieved through an in situ solvothermal process, using, for the first time, 3,4-dihydroxybenzhydrazide (DHBH) and poly[3,4-dihydroxybenzhydrazide] (PDHBH) as stabilizers. Transmission electron microscopy (TEM) analysis showed the formation of spherical MNC, X-ray photoelectronic spectroscopy (XPS) and Fourier transformed infrared (FT-IR) analysis proved the existence of the polymer shell. Magnetization measurement showed saturation magnetization values of 50 emu/g for PDHBH@MNC and 60 emu/g for DHBH@MNC with very low coercive field and remanence, indicating that the MNC are in a superparamagnetic state at room temperature and are thus suitable for biomedical applications. MNCs were investigated in vitro, on human normal (dermal fibroblasts-BJ) and tumor (colon adenocarcinoma-CACO2, and melanoma-A375) cell lines, in view of toxicity, antitumor effectiveness and selectivity upon magnetic hyperthermia. MNCs exhibited good biocompatibility and were internalized by all cell lines (TEM), with minimal ultrastructural changes. By means of flowcytometry apoptosis detection, fluorimetry, spectrophotometry for mitochondrial membrane potential, oxidative stress, ELISA-caspases, and Western blot-p53 pathway, we show that MH efficiently induced apoptosis mostly via the membrane pathway and to a lower extent by the mitochondrial pathway, the latter mainly observed in melanoma. Contrarily, the apoptosis rate was above the toxicity limit in fibroblasts. Due to its coating, PDHBH@MNC showed selective antitumor efficacy and can be further used in theranostics since the PDHBH polymer provides multiple reaction sites for the attachment of therapeutic molecules.

Morphologic, structural, and magnetic characterization of cobalt ferrite nanoparticles synthesized at different temperatures

In this study we report on the synthesis and characterization of cobalt ferrite (CoFe2O4) nanoparticles (NPs), synthesized by chemical co-precipitation in alkaline medium. Two samples were synthesized at two different temperatures, 35 and 90 oC. Both samples were characterized by Transmission Electron Microscopy (TEM), x-ray diffraction (XRD), and room-temperature (RT) magnetization. Two samples showed superparamagnetic behavior (SPM) at RT. TEM reveals morphological mean diameter increasing 5.8 nm to 10.4 nm, with the increase of the co-precipitation temperature. XRD confirm the inverse cubic spinel structure. The RT magnetization curves were analyzed by the first-order Langevin function averaged out by a lognormal distribution function of magnetic moments. This analysis showed saturation magnetization and magnetic moment increases from 60.2 to 74.8 emu/g and from 3.9 x 103 to 8.2 x 103 mB, respectively.

Nano-sized Fe3O4@SiO2-molecular imprinted polymer as a sorbent for dispersive solid-phase microextraction of melatonin in the methanolic extract of Portulaca oleracea, biological, and water samples

In this study, a magnetic molecularly imprinted polymer (MMIP (Fe3O4@SiO2-MIP)) was used for the dispersive magnetic solid-phase microextraction (d-MSP-μ-E) to design an easy and effective method for melatonin (MLT) extraction in the methanolic extract of Portulaca oleracea, human urine and plasma, and water samples. HPLC with UV detection was utilized, and pH, the type and volume of eluent, MMIP mass, and contact time were considered as effective factors in the study of MLT separation and pre-concentration. These factors were optimized by Plackett–Burman and multi-objective response surface methodology (RSM). The values were 10 mg, 14 min, 4.2, methanol, 0.180 mL, 2.5 min, for the MMIP mass, time of sorption, sample pH, eluent type, eluent volume, and time of elution, respectively. At the optimum conditions, the limit of detection (LOD) was 0.046 ng mL−1, and the limit of quantification (LOQ) was 0.156 ng mL−1. The sorption capacity of the proposed MMIP sorbent was 109.1 mg g−1 at the optimum conditions. Besides, linear dynamic range (LDR) was 0.2–4200 ng mL−1, and the precision of the method (RSD %) for triplicate measurements was <6.1%. The MMIP showed saturation magnetization of 19.75 emu g−1, resulting in fast separation of the sorbent. The sorption test revealed the high sorption capacity of the MMIP for MLT and its homogeneous binding sites. In all spiked levels (50, 100, 200, and 500 ng mL−1), 93.07–104.1% was the range obtained for the recovery of MLT. The relative selectivity factor (β) values of MLT/tryptophan, MLT/serotonin, MLT/ferulic acid, MLT/mefenamic acid, MLT/quercetin, MLT/luteolin, and MLT/chlorogenic acid were 1.60, 1.68, 2.02, 2.38, 2.32, 2.40, and 2.50, respectively. The results of desorption–regeneration cycles (seven times) by employing the MMIP showed the high stability of the resultant material. In conclusion, the MMIP combined with the magnetic separation showed a specific sorption behavior for MLT and suggested a simple, flexible, selective, and powerful analytical tool.

Facile Synthesis and Characterization of Nanospinel Ferrites: Structural, Magnetic, and Optical Studies

Nanoparticles of spinel ferrites with composition MFe2O4 (M = Zn, Ni) have been effectively synthesized by hydrothermal and sol-gel routes, in which Triton-X 100 is used as a surfactant. The structure of ferrite nanoparticles has been characterized by X-ray diffraction, which has showed single cubic spinel phases for all the samples. The surface morphology and elemental composition have been examined by field emission-scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) spectroscopy. A combined morphology in shape of sphere, octagon, and agglomerated flakes were found on FESEM images for the nanoparticles synthesized by both methods. FTIR showed underlying absorption bands pertinent to the stretching vibration of metal at the octahedral and tetrahedral sites. Vibrating sample magnetometer (VSM) results showed saturation magnetization (Ms) and remanence (Mr) for spinels prepared by hydrothermal route to be more than those produced by sol-gel methods. The optical band gap values were estimated by diffuse UV-visible reflectance spectroscopy (DRS).

Alternating Magnetic Field and Ultrasound Waves as Size Controlling Parameters in Preparation of Superparamagnetic Fe3O4 Nanoparticles

Magnetic nanoparticles have been studied extensively owing to their widespread applications. Here, a novel and simple co-precipitation method is introduced in the presence of an external alternating magnetic field along with ultrasound waves for the synthesis of uniform magnetite (Fe₃O₄) nanoparticles with an average particle size of below 10 nm, the results of which were compared further. These agitating probes were employed to induce nucleation process of Fe₃O₄ nanoparticles resulting in creation of such particles with remarkable magnetic properties. These were assessed by XRD, TEM, vibrating sample magnetometer (VSM), AFM, and magnetic force microscopy (MFM) analyses. XRD patterns revealed the spinel phase of the obtained magnetite. The size and morphology of the nanoparticles were determined by AFM, TEM, and HR-TEM. The results indicated efficient control over size distribution in such new processes. The magnetic properties of the prepared Fe₃O₄ nanoparticles were characterized by MFM and VSM, demonstrating their superparamagnetic behavior. They showed saturation magnetization ranging from 57.4 to 79.4 emu/g with coercivity of 11.9 to 12.55 Oe, depending on the applied procedure.

Multifunctional solution blow spun NiFe–NiFe2O4 composite nanofibers: Structure, magnetic properties and OER activity

Multifunctional nanomaterials are of great technological interest due to a wide range of applications. This study reports the structure, magnetic properties and electrocatalytic activity to oxygen evolution reaction (OER) of NiFe–NiFe2O4 composite nanofibers prepared by solution blow spinning (SBS) with an average diameter of 133.4 nm. X-ray diffraction (XRD) analysis revealed that NiFe alloy crystallites have an average size of 26.3 nm. The magnetization versus temperature (MxT) and magnetization versus magnetic field (MxH) measurements show saturation magnetization of 123 emu g−1 and thermal blocking temperature of 117 K. The MxT measurements show a quick response of the composite sample to magnetic field variations of ±0.3 Oe, indicating that the solution blow spun material has great potential for magnetic sensor applications. From an electrocatalytic point of view, nanofibers show a low overpotential of 316 mV vs RHE at J = 10 mA cm−2, and a significant turnover frequency (TOF) of 4.03 s−1 at only 400 mV. NiFe–NiFe2O4 nanofibers have an excellent chemical stability as revealed by chronopotentiometry analysis along 15 h. These results stand solution blow spun NiFe–NiFe2O4 composite nanofibers in line with the best NiFe-based catalysts reported in the literature.

SPIONs/3D SiSBA-16 based Multifunctional Nanoformulation for target specific cisplatin release in colon and cervical cancer cell lines

Multifunctional nanomaterials can be used for dual applications: drug delivery as well as in bioimaging. In current study, we investigated potential use of silica based supports; 3D cage type SiSBA-16 (S-16), monodispersed hydrophilic spherical silica (HYPS) and mesocellular foam (MSU-F) for cisplatin (Cp) delivery. To obtain magnetic resonance characteristics, 10 wt% iron oxide was loaded through enforced adsorption technique. For pH stimuli responsive release of Cp, 10 wt%SPIONs/S-16 was functionalized with 3-(Aminopropyl)triethoxysilane (A) and poly acrylic acid (PAA) termed as 10 wt%SPIONs/S-16-A-Cp and 10 wt%SPIONs/S-16-APAA-Cp. By TEM analysis, the average diameter of the SPIONs was found to range between 10–60 nm. VSM analysis showed saturation magnetization over S-16, HYPS and MSU-F were in the following order: 10 wt%SPIONs/HYPS (4.08 emug−1) > 10 wt%SPIONs /S-16 (2.39 emug−1) > 10 wt%SPIONs/MSU-F (0.23 emug−1). Cp release study using dialysis membrane in PBS solution over 10 wt%SPIONs/S-16 nanoformulations showed highest cumulative release (65%) than 10 wt%SPIONs/MSU-F-A-Cp (63%), 10 wt%SPIONs/HYPS-A-Cp (58%), and Cp-F127/S-16 (53%), respectively. 10 wt%SPIONs/S-16-A-Cp and 10 wt%SPIONs/S-16-APAA-Cp were evaluated for in vitro target anticancer efficiency in human cancer cell lines (colon cancer (HCT 116), cervical cancer (HeLa)) and normal cells (Human embryonic kidney cells (HEK293) using MTT and DAPI staining. 10 wt%SPIONs/S-16-A-Cp treated Hela and HCT116 cancerous cell lines showed significant control of cell growth, apoptotic activity and less cytotoxic effect as compared to Cp and 10 wt%SPIONs/S-16. Target specific Cp release in the cells shows that 10 wt%SPIONs/S-16-A-Cp can be easily upgraded for magnetic resonance imaging capability.

Fabrication of magnetic tunnel junctions with a metastable bcc Co3Mn disordered alloy as a bottom electrode

We fabricated MgO barrier magnetic tunnel junctions (MTJs) with a Co3Mn alloy bottom and FeCoB top electrodes. The (001)-oriented epitaxial films of the metastable bcc Co3Mn disordered alloys obtained showed saturation magnetization of approximately 1640 emu cm−3. The transmission electron microscopy showed that the MgO barrier was epitaxially grown on the Co3Mn electrode. Tunnel magnetoresistance of approximately 150% was observed at room temperature after the annealing of MTJs at 350 °C, indicating that bcc Co3Mn alloys have relatively high spin polarization.

Hollow Fe₃O₄/Graphene Oxide Nanocomposites as Novel Rapamycin Carrier: Formulation Optimization and In Vitro Characterization.

In the present research an attempt was made to develop and optimize rapamycin (Rapa) loaded hollow magnetic Fe3O4/graphene oxide (Fe3O4/GO) nanocomposites using solvent evaporation technique and response surface methodology (RSM). A Box-Behnken design (BBD) with a three-level, three-factor was used to determine preparation parameters that would achieve the highest encapsulation efficiency (EE) and drug loading capacity (DLC). At optimum conditions such as mass ratio of Rapa to Fe3O4/GO (Rapa: Fe3O4/GO) 0.45, oscillation rate 144.0, and volume ratio of water to solvent (W/S) 4.2, the EE and DLC of experimentally prepared particles reached 84.92 ± 5.50% and 28.68 ± 2.54% respectively. The morphological assessment results showed that hollow Fe3O4 nano-aggregates were evenly and tightly dispersed on the layer of GO membrane. After the addition of GO and encapsulation of Rapa, the Fe3O4/GO nanocomposites and Rapa loaded magnetic Fe3O4/GO (Fe3O4/GO-Rapa) nanocomposites showed saturation magnetization of 57.77 and 40.71 emu/g respectively. The drug releasing experiment indicated a slightly acidic atmosphere, which was suitable for Rapa releasing from the obtained Fe3O4/GO nanocomposites. The cell counting Kit-8 (CCK-8) assays demonstrated the hollow Fe3O4/GO nanocomposites could effectively improve the efficacy of Rapa in killing HepG2 cells, which displayed a concentration-dependent manner. All these results suggested the prepared Fe3O4/GO nanocomposites have a potential application in drug delivery system.

Structural, optical and magnetic properties of CeO2 nanowires with nonmagnetic Mg2+ doping

Here we report nonmagnetic Mg doped CeO2 (Ce1-xMgxO2, 0.00 ≤ x ≤ 0.08) synthesized via a facile hydrothermal method. The influence of Mg doping on the structure, morphology, optical and magnetic properties of CeO2 were examined by XRD, SEM, TEM, XPS, Raman, UV–vis and M-H curve. The SEM and TEM images display that as-synthesized samples are composed of the bundle of nanowires. Raman scattering shows that Mg doping causes a huge redshift of F2g mode. The absorption spectra indicate that band gap energy becomes narrow and drops to 3.00 eV with Mg doping, which are attributed to the presence of defects forming a band of electron states. Magnetic measurements show saturation magnetization (MS) initially increases and then decreases and the largest MS of 1.5 × 10−3 emu/g appears at 4 at.% Mg-doped CeO2, which is likely explained by a VO mediated F-center exchange (FCE) mechanism.

Magnetic, microwave absorption and structural properties of Mg\u2013Ti added Ca\u2013M hexaferrite nanoparticles

The Mg2+ and Ti4+ ions substituted M-type Ca(MgTi)xFe12−2xO19 (x = 0, 0.3, 0.6, 0.9) hexagonal ferrites (x = 0, 0.3, 0.6, 0.9) were synthesized by the citrate sol–gel method. The microwave absorption, crystal structure, magnetic and morphology of the nanopowders were investigated with vector network analyzer, X-ray diffraction (XRD), vibrating sample magnetometer and transmission electron microscopy. XRD results verified the formation of M-type hexagonal structures. The particle size estimated by the Scherer formula. Results illustrated particles size is less 100 nm. The hysteresis loops showed saturation magnetization increased from 72 to 98 kA m−1 while coercive force decreased from 1710 to 428 Oe with Mg–Ti content. Microwave absorption properties measured by the standing-wave-ratio method in the Ku band frequency. The observations showed that Ca(MgTi)xFe12−2xO19 nanopowders have extraordinary microwave absorption properties. It is observed bandwidth 6.3 gigahertz (12.5–18.8 GHz with respect to − 15 dB reflection loss) for composite x = 0.6. Furthermore, the results showed a minimum reflection loss − 31.5 and − 39 dB for composites 0.6 and 0.9, respectively. It should be pointed out thickness of the composites are 1.9 mm.

Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

A novel bio-sorbent comprising encapsulated Agrobacterium fabrum (SLAJ731) and iron oxide nanoparticles for removal of crude oil co-contaminant, lead Pb(II)

A novel adsorbent, iron oxide nanoparticles and A. fabrum strains encapsulated in calcium alginate, was prepared for the removal of lead. The crude oil degrading strain was isolated from core samples from Assam Oilfield, India and was able to resist lead up to 2900mgL−1 thus proving to be a highly lead tolerant. Chemically synthesized Fe3O4 magnetic nanoparticles (10–20nm) by co-precipitation method were characterized using various techniques. Vibrating Sample Magnetometer (VSM) showed saturation magnetization of 46.6emug−1, indicating superparamagnetic nature of synthesized MNPs, which will aid in separation of biosorbent after adsorption. Lead removal was studied using the bio-sorbent synthesized by immobilizing biomass and MNPs in calcium alginate beads at 200rpm and 37°C, and the adsorption capacity was found to be maximum at pH 5.5. Adsorption kinetics was examined using pseudo first order, pseudo second order and intra-particle diffusion (IPD) models. The kinetic data agreed to pseudo second order model and the adsorption rate constant (k2) decreased with an increase in initial concentrations. Initial adsorption rate (h, mgg−1min−1) was found to be kinetically controlled and the function of initial Pb(II) concentration. The IPD was found rate limiting step after 60min of adsorption. Adsorption data were fitted well to Langmuir isotherm. The maximum adsorption capacity of the synthesized bio-sorbent was found to be 197.02mgg−1. Thermodynamic studies suggested that the adsorption process was spontaneous and endothermic in nature. Biosorbent showed good adsorption capacity even after repeatedly using them for five consecutive cycles without compromising much with adsorption efficiency.