Eur. Phys. J. Appl. Phys. 43, 145-148 (2008)
https://doi.org/10.1051/epjap:2008095

Superparamagnetic iron oxide nanoparticles – Proton Nuclear Magnetic Resonance Dispersion curves

¹ Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
² Centro de Física da Matéria Condensada - UL, Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal
³ Escola Superior de Tecnologia da Saúde de Lisboa, Av. D. João II, Lote 4.69.01, 1990-096 Lisboa, Portugal

Corresponding author: alexandra.carvalho@estesl.ipl.pt

Received: 11 December 2007
Revised: 20 March 2008
Accepted: 3 April 2008
Published online: 30 May 2008

Abstract

Superparamagnetic nanoparticles are widely used as contrast agents for magnetic resonance imaging. We present the Proton Nuclear Magnetic Resonance Dispersion curves for colloidal suspension of iron oxide nanoparticles used as contrast agents. The systems studied are composed of iron oxide nanoparticles of two different sizes, 80–150 nm dextran coated and 300–400 nm silicon coated. Previous studies show that the longitudinal relaxation time dispersion as a function of the proton Larmor frequency is not easily obtained for the aqueous colloidal suspension of 300–400 nm diameter nanoparticles. We obtained this system longitudinal relaxation time dispersion over a broad range of magnetic fields in a viscous medium. A theoretical model that accounts for the relaxation rate of water protons under the influence of such colloidal superparamagnetic nanoparticles was fitted to the experimental data of both systems. The fit allows access to characteristic parameters of superparamagnetic nanoparticles such as the Néel relaxation time, the nanoparticle radius, particle's magnetic moment and translational correlation time, important parameters for the contrast agent efficiency.