Abstract #0034

A Novel Dual MRI-PARACEST/Fluorescent Probe for the Detection of Cathepsin-D Activity in Alzheimer's Disease

Robert Ta^1,2, Alex Li¹, Mojmir Suchy,^1,3, Robert Hudson³, Stephen Pasternak^4,5, Robert Bartha^1,2

¹Imaging Research Group, Robarts Research Institute, London, Ontario, Canada; ²Medical Biophysics, University of Western Ontario, London, Ontario, Canada; ³Chemistry, University of Western Ontario, London, Ontario, Canada; ⁴Molecular Brain Research Group, Robarts Research Institute, London, Ontario, Canada; ⁵Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada

A novel dual magnetic resonance/fluorescent probe has been designed for molecular targeting of Cathepsin D in Alzheimer's disease. The MRI contrast of this probe has been detected using the on-resonance paramagnetic agent chemical exchange effect (OPARACHEE) method. Greater than a 1% OPARACHEE contrast was observed in 1.5 mM Tm³⁺-DOTA-Glycine in a 5% BSA phantom. The dual probe demonstrated uptake into neuronal cells by confocal microscopy and had no toxic effects on these cells at the concentrations tested.