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[Display omitted] • Hierarchical structured MnFe 2 O 4 nanospheres were prepared through a solvothermal method. • Uniform particle size, mesoporous characteristic and superparamagnetic behavior. • A high performance magnetorheological fluid based on MnFe 2 O 4 nanospheres. • Typical magnetorheological effect and improved sedimentation stability were achieved. In this research, novel hierarchically structured cauliflower-shaped MnFe 2 O 4 nanospheres were synthesized via a simple solvothermal method and their potential application for high performance magnetorheological fluids was investigated. The samples were comprehensively characterized using FE-SEM, TEM, FTIR, XRD, BET, TGA, XPS and VSM. It was revealed that the prepared MnFe 2 O 4 nanospheres exhibited hierarchical cauliflower-like morphology and the average particle size was found to be 182 nm. More importantly, the MnFe 2 O 4 nanospheres demonstrated typical mesoporous structure, high specific surface area of 30.3 m2/g and moderate saturation magnetization of 29.3 emu/g, which were suitable for preparation of a uniform and stable MR suspension. The rheological performances comprising shear stress, viscosity, storage modulus and loss modulus of MR fluid under different external magnetic fields were measured using a dynamic rotational rheometer. The results indicated that the MR fluid possessed enhanced MR responses as the magnetic field intensity increased, which were attributed to the rapid formation of robust chain-like structures composed of MnFe 2 O 4 nanospheres inside the MR suspension. In addition, it was observed that the sedimentation stability of MR fluid containing MnFe 2 O 4 nanospheres was much more prominent than that of the suspension based on spherical carbonyl iron particles in the same testing period. [ABSTRACT FROM AUTHOR]

In this study, manganese ferrite/graphene oxide (MnFe 2 O 4 /GO) nanocomposites as controlled targeted drug delivery were prepared by a facile sonochemical method. It was found that GO nanosheets were fully exfoliated and decorated with MnFe 2 O 4 nanoparticles having diameters of 5–13 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of the obtained MnFe 2 O 4 /GO with saturation magnetization of 34.9 emu/g at room temperature. The in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared MnFe 2 O 4 /GO even at the concentration as high as 150 μg/mL. Doxorubicin hydrochloride (DOX) as an anti-tumor model drug was utilized to explore the application potential of MnFe 2 O 4 /GO for controlled drug delivery. The drug loading capacity of this nanocarrier was as high as 0.97 mg/mg and the drug release behavior showed a sustained and pH-responsive way. [ABSTRACT FROM AUTHOR]