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Abstract #0888

Novel Two Step PAMAM Dendrimers for Targeted MRI of TfR Expression

Cesar A. Berrios-Otero1, Steven Isaacman2, Ben B. Bartelle1, Kamila U. Szulc1, James Canary2, Daniel H. Turnbull1,3

1Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, USA; 2Chemistry, New York University, New York, USA; 3Radiology, NYU School of Medicine, New York, USA

Paramagnetic contrast agents targeted to cell membrane receptors are currently of great interest for molecular imaging with MRI. In addition to the advantages of imaging endogenous receptors, receptor targeted MRI has also been proposed as a method for imaging transgene expression. Previous studies have used gadolinium chelates as T1-agents for targeting. One limitation of current targeting methods, especially with T1-agents, is the low sensitivity for detection, suggesting the need for more effective amplification schemes. Here we have tested a two-step strategy based on PAMAM dendrimers, with the primary dendrimer targeted to Transferrin Receptor, and the secondary dendrimer containing up to 50 Gd-DTPA molecules for amplification of the T1 relaxation effects.