Development of an Activatable MRI T2 Agent Sensitive to NADH

Elizabeth A. Osborne¹, Angelique Y. Louie²

We have developed MRI contrast agents based on paramagnetic nanoparticles functionalized with molecular switches, that are capable of reporting on redox conditions. The molecular switches, spirooxazine, change conformation between hydrophilic and hydrophobic isomers in response to NADH and peroxide. This isomerization directs aggregation and dispersion of the nanoparticles yielding a modulation of MR signal. We have synthesized and characterized iron oxide nanoparticles coated with dextran that has been cross-linked and aminated thus allowing attachment of spirooxazine. Preliminary results indicate successful preparation of the particles, and size and relaxivity differences have been observed upon reaction with NADH/peroxide in solution studies.