This paper highlights the relation between the shape of iron oxide (Fe3O4) particles and their magnetic sensing ability. We synthesized Fe3O4 nanocubes and nanospheres having tunable sizes via solvothermal and thermal decomposition synthesis reactions, respectively, to obtain samples in which the volumes and body diagonals/diameters were equivalent. Vibrating sample magnetometry (VSM) data showed that the saturation magnetization (Ms) and coercivity of 100–225 nm cubic magnetic nanoparticles (MNPs) were, respectively, 1.4–3.0 and 1.1–8.4 times those of spherical MNPs on a same-volume and same-body diagonal/diameter basis. The Curie temperature for the cubic Fe3O4 MNPs for each size was also higher than that of the corresponding spherical MNPs; furthermore, the cubic Fe3O4 MNPs were more crystalline than the corresponding spherical MNPs. For applications relying on both higher contact area and enhanced magnetic properties, higher-Ms Fe3O4 nanocubes offer distinct advantages over Fe3O4 nanospheres of the same-volume or same-body diagonal/diameter. We evaluated the sensing potential of our synthesized MNPs using giant magnetoresistive (GMR) sensing and force-induced remnant magnetization spectroscopy (FIRMS). Preliminary data obtained by GMR sensing confirmed that the nanocubes exhibited a distinct sensitivity advantage over the nanospheres. Similarly, FIRMS data showed that when subjected to the same force at the same initial concentration, a greater number of nanocubes remained bound to the sensor surface because of higher surface contact area. Because greater binding and higher Ms translate to stronger signal and better analytical sensitivity, nanocubes are an attractive alternative to nanospheres in sensing applications.

Biocompatible core–shell CoFe2O4@HAp magnetic nanoparticles were successfully prepared by a simple two-step hydrothermal process, and their physicochemical and magnetic properties were studied.

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In the present work, surface modification of iron oxide (Fe 3 O 4) nanoparticles with biocompatible fluorapatite (FAP) coating achieved by a simple method and its characterizations using XRD, TEM, FT-IR, DSC and VSM are reported. TEM images revealed the spherical morphology of Fe 3 O 4 nanoparticle and rod-like FAP coated Fe 3 O 4 nanoparticles with size of about 12 and 30 nm, respectively. Magnetic measurements (M-H) of both the samples exhibited superparamagnetic behavior at 300 K. FAP coated Fe 3 O 4 nanoparticles enhance the cell viability and colloidal stability when compared to Fe 3 O 4 nanoparticles. These results demonstrate that FAP coated Fe 3 O 4 nanoparticles could be a suitable candidate for biomedical applications.

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