Skip to main content
. Author manuscript; available in PMC: 2014 Apr 18.
Published in final edited form as: Nanomedicine (Lond). 2012 Jul 26;7(11):1697–1711. doi: 10.2217/nnm.12.65

Figure 2. Characterization of superparamagnetic iron oxide nanoparticles.

Figure 2

(A) Photon correlation spectroscopy at iron concentrations of 0.2 mg/ml in 0.22-µm-filtered water (z-weighted distribution). (B) ζ-potential–pH function. The ζ-potential–pH function of the nanoparticles was measured using a Malvern Zetasizer Nano ZS-90 (Malvern Instruments Ltd, Worcestershire, UK). The nanoparticles have a slightly negative surface charge over pH 3–10 and a surface charge of −6 mV in the neutral pH range. (C) Transmission electron microscopy (TEM) image of dextran–SPIO nanoparticles. The TEM image was obtained using an EM 912 TEM at 100 keV. The dextran coating typically is not visible with high-energy electrons (100 keV), which explains the apparently higher hydrodynamic diameter resulting from photon correlation spectroscopy size measurements (100-nm diameter), in comparison with the diameter of the iron oxide core from TEM images (50-nm diameter). (D) The amplitude-dependent SLP was estimated by measuring time-dependent heating at several applied amplitude (voltage) values from 4 to 94 kA/m. The SLP was estimated from the slope, ΔT/Δt, of the time–temperature curve.

SLP: Specific loss power; SPIO: Superparamagnetic iron oxide.