Magnetic property measurement system 3 superconducting quantum inference device squid magnetometer

SPION’s magnetic, physical, and hydrodynamic diameters were determined and the results shown in Fig. 11. Magnetic size distribution was determined using a Quantum Design Magnetic Property Measurement System 3 (MPMS3) Superconducting Quantum Inference Device (SQUID) magnetometer. Magnetization curves at room temperature were obtained for liquid samples in a PTFE sample holder with 100 μL of SPIONs suspended in water. Physical diameters were obtained using a Hitachi H 7000 Transmission Electron Microscope (TEM). Images of SPIONs at 1 mg/mL sampled on an Ultrathin Carbon Type A (3–4nm) with removable formvar grid from TedPella were acquired using a Veleta CCD side mount camera and were analyzed using ImageJ. Hydrodynamic diameters were determined through room temperature dynamic light scattering (DLS), using a particle size analyzer (Zeta PALS, Brookhaven Instruments). For DLS, aqueous nanoparticle samples (500 μL) with concentration between 0.1 and 1 mg/mL were filtered using a 0.2 μm syringe filter prior to measurements.

A Quantum Design Magnetic Property Measurement System 3 (MPMS 3) Superconducting Quantum Inference Device (SQUID) magnetometer was used to study the intrinsic properties of the oleic acid coated magnetic nanoparticles synthesized. Magnetization curves at room temperature were obtained for liquid samples in a PTFE sample holder with 100 μL of iron-oxide nanoparticles suspended in hexane/water. The volume-weighted median magnetic diameter (D_mv) and geometric deviation of the magnetic nanoparticle samples were determined by fitting the superparamagnetic equilibrium magnetization curve to the Langevin function, weighted using a lognormal size distribution n_v(D_m), as commonly done in the literature.^{28 ,40 ,85 ,86} Two important assumptions are made in this analysis: the magnetic domains are spherical and the magnetic domains possess a magnetization equal to that of bulk magnetite (446,000 A/m). The corresponding equations are (1) to (3) and the volume median diameter obtained was converted to volume mean using equation (6). The saturation magnetization was deduced from the maximum of the magnetization obtained from the magnetization curves.