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Abstract #0889

REACTION: Release Activation of Iron Oxide Nanoparticles: A Novel Environmentally Sensitive MRI Paradigm

Dorit Granot1, Erik M. Shapiro1,2

1Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, USA; 2Department of Biomedical Engineering, Yale University, New Haven, CT, USA

We report a new enzyme/contrast agent paradigm which achieves enzymatically responsive changes in relaxation times of magnetically labeled cells. Cells are labeled with biopolymer-coated particles which are cleavable by a specific enzyme. This coating restricts the approach of water to the particles, preventing the magnetic core from relaxing protons. The reactive enzyme potentially can be engineered as a reporter protein, whose expression can be regulated. The enzyme cleaves the particle coating, releasing the magnetic center, increasing the relaxivity of the agent. We demonstrate the principal of enzyme-mediated changes in nanoparticle relaxivity in cell free assays, in-cellulo, and in-vivo in animals.