Open Access

Dominique Piché, Isabella Tavernaro, Jana Fleddermann, Juan G. Lozano, Aakash Varambhia, Mahon L. Maguire, Marcus Koch, Tomofumi Ukai, Armando J. Hernández Rodríguez, Lewys Jones, Frank Dillon, Israel Reyes Molina, Mai Mitzutani, Evelio R. González Dalmau, Toru Maekawa, Peter D. Nellist, Annette Kraegeloh, Nicole Grobert

• Extraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r2/r1 ratio suitable for a T1 contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T1 MRI. Our study demonstrates the potential of ESCIoNs as T1 MRI contrast agents.