- Oral presentation
- Open Access
CION v2.0: a better way to T1 enhancement with iron oxides
© Caruthers et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Introduction and purpose
Molecular imaging and nanomedicine approaches to the diagnosis, monitoring and treatment of cardiovascular diseases, e.g. atherosclerosis, could have significant consequence on medical practice and outcomes. Due to the exquisite sensitivity of MR to magnetic field disturbances of iron oxides (IO), a variety of IO-based agents have been utilized. However, despite many elegant new imaging techniques, the highly-sensitive detection and visualization of IO still depends on the disruption of the local magnetic field. Contrary to typical IO agents, we have presented a novel colloidal iron oxide nanoparticle (CION) that encapsulates multiple magnetite nanocrystals suspended in oil, encased in a lipid membrane thereby reducing T2* effects such that T1 effects can be detected. The purpose of this work was to develop a CION with improved longitudinal relaxivity (r1) and the ability to carry drugs.
To evaluate the role of IO concentration within the oil core, CION were created with [IO] of 7.5%, 15% and 45% (w/v) Fe3O4, both with and without cross-linking the outer lipid membrane. To compare the effect of iron phase, CION was made with mixed-phase maghemite (Fe2O3-Fe3O4) at 7.5% (w/v). CION were characterized using dynamic light scattering, vibrating sample magnetometer, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The r1 was calculated at 1.5 T using the Look-Locker technique to measure T1 of serial dilutions of CION. To demonstrate drug-carrying capability, fumagillin was incorporated into the outer surfactant. A dissolution study was performed over 3 d.
Targeted CION is a positive-contrast T1 agent wherein pure magnetite, low Fe concentration, and cross-linking each augment overall r1 relaxivity. Additionally, CION offers a good potential platform for targeted drug delivery exhibiting excellent drug retention in dissolution.
This article is published under license to BioMed Central Ltd.