Molecular Imaging Seminar Series

Molecular imaging is a novel field combining the global anatomical/physiologic scale of currently available in vivo imaging modalities with the detailed molecular/cellular scale of biochemistry and cell and molecular biology to obtain a visual representation and characterization of biological processes at the cellular/sub-cellular level in living subjects. We created this seminar series to discuss the most novel findings in this fast-developing field. We are focusing on studies in cancer, diabetes and neurodegenerative disorders, but are open to any other human pathology that could benefit from the molecular imaging approach.

We invite established investigators as well as graduate students to present and discuss their work. The series is open to researchers from the Martinos Center as well as from the interested scientific community within MGH and the greater Boston area. For more information please contact Dr. Anna Moore, Director, Molecular Imaging Laboratory, at amoore@helix.mgh.harvard.edu.

Upcoming and recent talks are listed below.

June 4th 2009

Tatjana Atanasijevic, Ph.D. Candidate in the Department of Nuclear Science & Engineering (MIT)
"Design and Development of Calcium Sensitive Contrast Agents for fMRI"    

10:00am, Bldg 75

ABSTRACT
We describe a new class of calcium sensitive contrast agents for magnetic resonance imaging based on conjugation of superparamagnetic iron oxide nanoparticles to the protein calmodulin (CaM) and to its target peptides.  CAM binds the peptides in the presence of calcium; this causes CaM- and peptide-conjugated nanoparticles to aggregate and produce large changes in T2 relaxivity.  One variant of the sensor responds reversibly to calcium concentrations around 1 µM Ca2+, but calcium-binding properties can be tuned by mutation of the protein domains. Because of the large changes on T2 relaxivity, particles can be used for MRI-based calcium sensing at concentrations in the nanomolar range.  This form of the sensor has relatively slow kinetic response (several seconds to minutes), which we are in the process of improving using much smaller nanoparticles. The second generation of the sensor, based on smaller lipid-coated nanoparticles, appears to have significantly improved aggregation kinetics, but also some stability issues.  We are currently working on the third generation of sensor, based on smaller nanoparticles with crosslinked lipid coating.  When combined with technologies for cellular delivery of nanoparticulate agents, the new sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens.