Article pubs.acs.org/Biomac
Multidentate Block-Copolymer-Stabilized Ultrasmall Superparamagnetic Iron Oxide Nanoparticles with Enhanced Colloidal Stability for Magnetic Resonance Imaging Nicky Chan,† Myriam Laprise-Pelletier,‡,§ Pascale Chevallier,‡,§ Andrea Bianchi,∥ Marc-André Fortin,*,‡,§,⊥ and Jung Kwon Oh*,†,⊥ †
Department of Chemistry and Biochemistry and Center for Nanoscience Research, Concordia University, Montreal, Quebec H4B 1R6, Canada ‡ Centre de Recherche du Centre Hospitalier Universitaire de Québec (CR-CHUQ), Axe Médecine Régénératrice, Québec, Québec G1L 3L5, Canada § Centre de recherche sur les matériaux avancés (CERMA), Department of Mining, Metallurgy and Materials Engineering, Université Laval, Québec, Québec G1V 0A6, Canada ∥ Département de Physique, Université de Montréal, Montréal, Quebec H3T 1J4, Canada ⊥ Centre Québécois sur les Matériaux Fonctionnels (CQMF), Pavillon Alexandre-Vachon-2634 Université Laval, Québec, Québec Canada S Supporting Information *
ABSTRACT: Ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) with diameters 4 nm (5−9 nm). For example, USPIOs stabilized with PEG (core diameter =5.4 nm) had r1 = 19.7 mM−1 s−1 at 1.5 T18 and r1 = 7.9 mM−1 s−1 at 3 T.19 In addition, commercially available dextran-coated counterparts including ferumoxtran-10 (AMI-227), ferumoxytol, and Supravist (SHU-555C) with core diameters in the range 5−8 nm and hydrodynamic diameter 7 months).18,19 Relaxometric Properties of MDBC−USPIOs. The relaxometric properties of the contrast agents were examined at clinical magnetic field strengths (1.41T, corresponding to 60 MHz). T1 and T2 of MDBC-stabilized USPIOs were measured at different Fe concentrations. From the slopes of the plots of 1/T1 and 1/T2 relaxation rates versus Fe content (Figure 4), longitudinal relaxivity r1 = 4.75 mM−1 s−1, transversal relaxivity r2 = 21.73 mM−1 s−1, and thus relaxometric ratio of r2/r1 = 4.74 were calculated. The r1 value of MDBC−USPIOs was similar to that of other reported USPIO systems with similar range of core diameters
