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Uniform Fe 3 O 4 submicron spheres assembled by tiny nanocrystals were fabricated via a facile one-step solvothermal strategy. The morphology, crystal structure, mesoporous characteristics, elemental composition and magnetic properties of the resultant magnetic particles were investigated extensively through various characterization techniques. The resulting Fe 3 O 4 submicron spheres were nearly monodisperse with an average diameter of 508 nm and demonstrated typical mesoporous structures and superparamagnetic behavior. The rheological responses of magnetorheological (MR) suspension composed of Fe 3 O 4 submicron spheres to different intensity of magnetic fields were investigated and the sedimentation stability tests were conducted and compared with that of carbonyl iron particles. The formed MR fluid behaved as Newtonian fluid without an external magnetic field and turned into Bingham behavior under the action of magnetic field. In addition, no significant settlement was observed in the recording period, showing an excellent sedimentation stability for the developed MR fluid. • Uniform hierarchical Fe 3 O 4 submicron spheres were synthesized by a solvothermal approach. • Mesoporous structure, high saturation magnetization and superparamagnetic behavior. • A stable magnetorheological fluid composed of Fe 3 O 4 submicron spheres. • Typical Bingham fluid behavior and high sedimentation stability. [ABSTRACT FROM AUTHOR]

This work details the design and synthesis of novel urchin-like α-FeOOH@MnO core-shell hollow microspheres for high-performance electrode materials for supercapacitors. The core-shell heterostructures were constructed by growing strip-like MnO nanostructures onto the urchin-like α-FeOOH hollow microspheres that were composed of nanorods. Based on the synergetic effects and multi-functionalities of both the MnO shell and urchin-like α-FeOOH hollow cores, the resulting urchin-like α-FeOOH@MnO core-shell hollow microspheres exhibited excellent electrochemical performance with a high specific capacitance of 597 F g at 1 A g, good rate capability (capacitance retention of 74.2% at 10 A g), and remarkable cycling stability (capacitance retention of 97.1% after 2000 cycles). Moreover, an asymmetric supercapacitor fabricated using α-FeOOH@MnO as positive electrode and activated carbon as negative electrode was found to deliver a high energy density of 34.2 W h kg and power density of 815 W kg. Graphical Abstract: Urchin-like α-FeOOH@MnO hollow microspheres demonstrated a high specific capacitance, rate capability and cycling stability, suggesting its promising potential for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: It is significant interest in developing novel multifunctional nanocarrier with complementary roles in recent years. Magnetic Fe3O4/graphene oxide (GO) nanocomposites with integrated characteristics of magnetic resonance imaging (MRI) and controlled drug delivery were prepared by an inverse co-precipitation method. The microstructure and physical properties of Fe3O4/GO nanocomposites were investigated by transmission electron microscope, wide-angle X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analyzer and superconducting quantum interference device magnetometer. The obtained nanocomposites exhibited superparamagnetic property with the saturation magnetization of 63.3 Am2 kg−1 at room temperature. In vitro MRI experiments revealed that Fe3O4/GO nanocomposites possessed an excellent MRI enhancement effect. 5-Fluorouracil (5-FU) as an anti-tumor model drug was loaded onto the surface of Fe3O4/GO nanocomposites. The drug loading capacity of this nanocarrier was as high as 0.37 mg mg−1 and the drug release behavior showed pH-dependence. The results suggested that the as-prepared Fe3O4/GO nanocomposites showed great potential as an effective multifunctional nanoplatform for MRI and controlled drug delivery. [Copyright &y& Elsevier]

Abstract: Polyvinylpyrrolidone-iodine (PVPI)-coated Fe3O4 nanoparticles were prepared by using inverse chemical co-precipitation method, in which the PVPI serves as a stabilizer and dispersant. The wide angle X-ray diffraction (WAXD) and selected area electron diffraction (SAED) results showed that the inverse spinel structure pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FTIR) results suggested that PVPI interacted with Fe3O4 via its carbonyl groups. Results of superconducting quantum interference device (SQUID) indicated prepared Fe3O4 nanoparticles exhibited superparamagnetic behavior and high saturation magnetization. T2-weighted MRI images of PVPI-coated Fe3O4 nanoparticles showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticles concentration in water at room temperature. These results indicated that the PVPI-coated Fe3O4 nanoparticles had great potential for application in MRI as a T2 contrast agent. [Copyright &y& Elsevier]

• Uniform hierarchical Fe 3 O 4 nanospheres were synthesized via a solvothermal method. • Mesoporous structure, moderate saturation magnetization and superparamagnetic behavior. • A stable magnetorheological fluid composed of Fe 3 O 4 nanospheres was formed. • Typical Bingham fluid behavior and enhanced sedimentation stability. In this study, hierarchically structured mesoporous Fe 3 O 4 nanospheres were synthesized using a solvothermal method and the application of the obtained Fe 3 O 4 nanospheres in magnetorheological (MR) fluid was investigated in detail. The morphology, microstructure and magnetic properties of the as-synthesized Fe 3 O 4 nanospheres were examined through different characterization techniques, such as SEM, TEM, XRD, XPS, BET and SQUID. The results of rheological measurements revealed that the prepared homogeneous MR fluid based on mesoporous Fe 3 O 4 nanospheres showed typical MR performances, exhibiting a rapid and reversible transition from a liquid-like to a solid-like state under the action of an external magnetic field. More importantly, it should be noted that the Fe 3 O 4 nanospheres-based MR fluid demonstrated enhanced a sedimentation stability as compared to that of carbonyl iron (CI) particles-based MR fluid. This finding was probably assigned to the particular mesoporous structure and the decreased density mismatch between two components of MR fluid. [ABSTRACT FROM AUTHOR]

This article presented a facile two-step hydrothermal strategy to anchor the Fe 3 O 4 nanoparticles on the surface of Zn Al LDH nanosheets, and investigated systematically the potential application of the constructed Fe 3 O 4 /Zn-Al LDH nanocomposites in the biomedical field of controlled drug delivery. It was revealed that the formed Fe 3 O 4 /Zn-Al LDH nanocomposites exhibited uniform mesopores, high surface area of 121.7 m2/g, good superparamagnetism and appropriate saturation magnetization of 40.7 emu/g. Due to these fascinating properties, this work explored the application of Fe 3 O 4 /Zn-Al LDH in the field of nanocarrier using the doxorubicin hydrochloride (DOX) as a model anticancer drug for the detailed investigations of drug loading capacity, controlled release behavior and cytotoxic effects under in vitro conditions. The Fe 3 O 4 /Zn-Al LDH showed a good drug storage capacity and a pH-responsive drug release profile. After loading the anti-cancer drugs, the DOX-loaded Fe 3 O 4 /Zn-Al LDH exhibited enhanced therapeutic effect on human hepatocellular carcinoma cells (HepG2), demonstrating that the fabricated Fe 3 O 4 /Zn-Al LDH nanocomposites have a great potential in cancer therapy. • Anchoring the Fe 3 O 4 nanoparticles on the surface of Zn Al LDH nanosheets. • Uniform mesopores, high specific surface area and superparamagnetic behavior. • Promising potential of constructed Fe 3 O 4 /Zn-Al LDH as a drug delivery vehicle. • A good drug storage capacity and a pH-responsive drug release profile. [ABSTRACT FROM AUTHOR]

• Hollow mesoporous Fe 3 O 4 nanospheres were prepared by a template-free solvothermal method. • The formation mechanism of hollow mesoporous nanospheres was proposed. • Superparamagnetic behavior with saturation magnetization of 74.9 emu/g. • In vitro negligible cytotoxicity for Fe 3 O 4 nanospheres even in high concentrations. • A promising drug delivery system with high drug loading capacity and pH-responsive feature. Monodisperse hollow mesoporous Fe 3 O 4 nanospheres have been successfully synthesized via a template-free one-pot solvothermal method under the existence of iron chloride hexahydrate, polyvinylpyrrolidone and urea. A proposed gas-bubble-assisted Ostwald ripening mechanism was allowed to explain the possible fabrication of hollow nanostructures. The formed Fe 3 O 4 nanospheres possessed a narrow particle size distribution with a average hydrodynamic diameter of 392 nm, superparamagnetic characteristics with high saturation magnetization of 74.9 emu/g, as well as the typical mesoporous structures with specific surface area of 27.3 m2/g. Furthermore, it was found that the bare hollow mesoporous Fe 3 O 4 nanospheres showed an insignificant cytotoxicity, but exhibited obvious cytotoxic effects towards HeLa cells after being loaded with the anti-cancer drug of DOX, which could be recommended as a promising and effective drug delivery system with high drug loading capacity and pH-responsive feature. The determined maximum drug loading capacity of DOX on this kind of hollow mesoporous Fe 3 O 4 nanospheres was as high as 0.36 ± 0.04 g/g, which can store and deliver effectively the anticancer drugs to induce death of cancer cells. [ABSTRACT FROM AUTHOR]

In the present work, monodisperse Fe 3 O 4 nanospheres with typical mesoporous structures and superparamagnetic characteristics were synthesized through a simple solvothermal approach. Various characterization experiments including SEM, TEM, XRD, XPS, BET and SQUID were performed to investigate in detail the morphology, microstructure, composition and physicochemical properties of the prepared Fe 3 O 4 nanospheres. It was found that the average diameter of Fe 3 O 4 nanospheres was determined to be about 207.3 nm with a relatively narrow size distribution. The analysis of nitrogen adsorption/desorption isotherms indicated that Fe 3 O 4 nanospheres represented typical mesoporous structures having a surface area of 20.68 m2/g. The magnetic property measurements demonstrated that the synthesized nanospheres behaved as superparamagnetic with a high saturation magnetization of 97.5 emu/g. Most importantly, the mesoporous Fe 3 O 4 nanospheres could be utilized as a potential anti-cancer drug carrier for doxorubicin hydrochloride (DOX). The drug loading capacity and in vitro drug release behavior of DOX in phosphate buffered solutions under different pH values (4.0, 5.5 and 7.4) were examined. The results showed that the developed drug delivery system based on mesoporous Fe 3 O 4 nanospheres exhibited a high drug loading capacity and a controlled drug release behavior. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, the magnetic molecularly imprinted polymers (M-MIPs) for bisphenol A were synthesized via facile one-step Pickering emulsion polymerization using Fe 3 O 4 nanoparticles as the only stabilizer. The synthesis was based on non-covalent molecular imprinting strategy and performed by thermally initiated radical polymerization. The morphology of M-MIPs microspheres was examined by the field emission scanning electron microscope. The result indicated that most of prepared M-MIPs microspheres appeared snowman-like shape instead of the regular spherical form. The binding performance of M-MIPs microspheres was researched through a batch of binding tests including binding kinetics and binding isotherm. M-MIPs could reach binding equilibrium within 60 min. The binding capacity of M-MIPs (16.20 μmol g−1) was higher than that of magnetic non-imprinted polymers (M-NIPs), whose binding capacity was 9.44 μmol g−1. The specific binding was also carried out with BPA and its structurally similar compounds. The result showed that the M-MIPs possessed high selectivity towards BPA with the imprinting factor of 1.69. The M-MIPs may be useful in the environmental and analytic fields. Novel snowman-like magnetic molecularly imprinted polymer microspheres were prepared through facile one-step Pickering emulsion polymerization combined with the jamming of Fe 3 O 4 nanoparticles at the droplet surfaces. [Display omitted] • Pickering emulsion polymerization is performed with Fe 3 O 4 as the only stabilizer. • Most of obtained M-MIPs microspheres exhibit snowman-like shape. • M-MIPs display excellent binding capacities and accurate recognition specificity. [ABSTRACT FROM AUTHOR]