NC100150 injection, a preparation of optimized iron oxide nanoparticles for positive‐contrast MR angiography

A preparation of monocrystalline iron oxide nanoparticles with an oxidized starch coating, currently in clinical trials (NC100150 Injection; CLARISCAN™), was characterized by magnetization measurements, relaxometry, and photon correlation spectroscopy. By combining the results with a measure of iron content, one can obtain the size and magnetic attributes of the iron cores, including the relevant correlation times for outer sphere relaxation (τSO and τD), and information about the interaction of the organic coating with both core and solvent. The results are 6.43 nm for the iron oxide core diameter, a magnetic moment of 4.38 × 10−17 erg/G, and a water-penetrable coating region of oxidized oligomeric starch fragments and entrained water molecules. The latter extends the hydrodynamic diameter to 11.9 nm and lowers the average diffusivity of solvent about 64% (which increases τD accordingly). The nanoparticles show little size-polydispersity, evidenced by the lowest value of r2/r1 at 20 MHz reported to date, an asset for magnetic resonance angiography. J. Magn. Reson. Imaging 2000;11:488–494. © 2000 Wiley-Liss, Inc.