Novel systems based on suspensions of colloidal magnetic nanoparticles have been investi-gated as perspective superparamagnetic contrast agents (CA) for magnetic resonance imaging (MRI). The nanostructures that we have studied contain surfactant-capped magnetite (Fe3O4) inorganic cores with different controlled sizes, ranging from 5.5 to 12 nm. The as-synthesized nanostructures are passivated by hydrophobic surfactants and thus are fully dispersible in nonpolar media. The magnetic nanocrystals have been transferred into aqueous media by a procedure based, on the surface intercalation and. coating with an amphiphilic polymer shell. The MRI efficiency in contrasting images, i.e., the NMR relaxivities r1and r 2, have been compared with. Endorem and Sinerem, commercial superparamagnetic MRI contrast agents. We found that our nanostructures exhibit r1and r2 relaxivities comparable to those of commercial CA over the whole frequency range. The MRI efficiency of our samples was related to their microstructural and. magnetic properties. The transverse relaxivity r2, leading the contrast, in "negative" super-paramagnetic agents, was found to improve as the diameter of the inorganic core is increased. The NMR relaxometry profile confirmed the nature of the physical mechanisms inducing the increase of the nuclear relaxation rates at low (magnetic anisotropy) and high (Curie relaxation) fields.
|Titolo:||Magnetic Resonance Imaging Contrast Agents Based on Iron Oxide Superparamagnetic Ferrofluids|
|Settore Scientifico Disciplinare:||Settore FIS/01 - Fisica Sperimentale|
Settore FIS/03 - Fisica della Materia
|Data di pubblicazione:||2010|
|Digital Object Identifier (DOI):||10.1021/cm9031557|
|Appare nelle tipologie:||01 - Articolo su periodico|