Michael K. Nkansah1, Erik M. Shapiro1,2
1Department of Biomedical Engineering, Yale University, New Haven, CT, United States; 2Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, United States
While magnetic relaxation switches (MRSws) have been developed using iron-oxide particles that cluster in the presence of an extracellular stimulus, the potential of using such systems to monitor intracellular events in vivo via MRI has not been investigated. Granot et al first demonstrated an MRSw operating in cellulo and in vivo via MRI using a Feridex/dextranase system. We demonstrate the fabrication of magnetic cellulose particles that are relaxometrically sensitive to cellulase digestion. In the off state, the particle remains intact. When switched on through the cleavage action of cellulase, the iron-oxide cores get dispersed, changing the relaxivity of the agent.