Functionalized Nanoparticles

We are developing a novel molecular imaging probe based on hyperpolarized silicon nanoparticles, providing a novel tool for measuring and imaging biological processes in health and disease. This project is the result of a recently-initiated multi-disciplinary collaboration with Charlie Marcus in the Harvard University Physics Department, Bruce Rosen at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital, Sangeeta Bhatia and David Cory of MIT, and Susan Kauzlarich of Univerisity of California, Davis.

Iron-oxide nanoparticle-based contrast agents have been used extensively in MRI to detect specific molecular targets as well as to label cells for cell tracking. However, traditional methods used for detecting iron-oxide nanoparticles suffer from several problems, including difficulty quantifying the iron-oxide concentration, and difficulty detecting the contrast agent in regions that undergo motion or have low native signal-to-noise ratio (SNR). Contrast agents containing hyperpolarized nuclei provide a novel method to overcome many of these problems. The use of hyperpolarized noble gases for lung imaging has clearly demonstrated the benefits of imaging hyperpolarized agents, providing both dramatically increased detection sensitivity as well as eliminating all background signals.

Recently, ¹³C imaging of ¹³C-hyperpolarized metabolites has provided a method for rapid metabolic profiling. However, the very short nuclear relaxation times of hyperpolarized agents used, typically less than 60 s for most ¹³C agents, is much too short for the imaging of targeted molecular probes that require several hours to both reach and bind their targets. We are using Si or SiO₂ nanoparticles, where the ²⁹Si is suitable for rapid hyperpolarization and has been shown to exhibit nuclear relaxation times as along as 5 hours. Our program includes the synthesis, biological functionalization, and hyperpolarization of silicon nanoparticles. Such ²⁹Si- based contrast agents will provide powerful and much needed new tools for targeted molecular imaging, cell tracking and the detection of tumors.

Recent Posters (click to download)