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Physicochemical characterization of ultrasmall superparamagnetic iron oxide particles (USPIO) for biomedical application as MRI contrast agents

Authors Mariagrazia Di Marco, Claudia Sadun, Marc Port, Irene Guilbert, Patrick Couvreur

Published 15 January 2008 Volume 2007:2(4) Pages 609—622



Mariagrazia Di Marco1,3, Claudia Sadun2, Marc Port3, Irene Guilbert3, Patrick Couvreur1, Catherine Dubernet1

1Univ Paris-Sud, Châtenay Malabry, France; 2Dipartimento di Chimica, Università degli Studi di Roma “La Sapienza”, Roma, Italy; 3Guerbet, Centre de Recherche, Roissy CdG Cedex, France

Abstract: Ultrasmall superparamagnetic iron oxide (USPIO) particles are maghemite or magnetite nanoparticles currently used as contrast agent in magnetic resonance imaging. The coatings surrounding the USPIO inorganic core play a major role in both the in vitro stability and, over all, USPIO’s in vivo fate. Different physicochemical properties such as final size, surface charge and coating density are key factors in this respect. Up to now no precise structure – activity relationship has been described to predict entirely the USPIOs stability, as well as their pharmacokinetics and their safety. This review is focused on both the classical and the latest available techniques allowing a better insight in the magnetic core structure and the organic surface of these particles. Concurrently, this work clearly shows the difficulty to obtain a complete physicochemical characterization of USPIOs particles owing to their small dimensions, reaching the analytical resolution limits of many commercial instruments. An extended characterization is therefore necessary to improve the understanding of the properties of USPIOs when dispersed in an aqueous environment and to set the specifi cations and limits for their conception.

Keywords: USPIO, contrast agents, iron oxide, physicochemical characterization