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Monday, Nov. 22, 2010, 10:30 a.m., NSERL 3.204












“Quantum Dots for Cellular and Molecular Imaging:
Unusual Optical Properties and Cellular Toxicity”

Dr. Aaron M. Mohs, Georgia Tech and Emory University

Semiconductor quantum dots (QDs) are light-emitting nanoparticles that are emerging as a new class of fluorescent labels for biology and medicine. In comparison with organic dyes and fluorescent proteins, they have unique optical and electronic properties, including size-tunable light emission, superior signal brightness, resistance to photobleaching and broad absorption spectra for simultaneous excitation of multiple fluorescence colors. Yet QDs are typically composed of highly toxic elements, which may lead to unintended toxicity for those directly exposed in the nanoparticle fabrication or by organisms in contact with QD waste. To realize the vast potential of QDs, recent efforts have focused on reducing the amount of toxic metals in them, especially cadmium. For example, ZnSe is used for doped QDs and as a compressive shell material to tune the emission color of QDs. In this presentation, a comparison of heavy-metal-rich and heavy-metal-free quantum dots reveals that nanocrystal surfaces can exhibit unique optical and chemical properties, which can elicit unexpected toxicological attributes. These examples illustrate that nanoparticle cytotoxicity is significantly more complex than conventionally believed.

Aaron Mohs received his PhD in pharmaceutics and pharmaceutical chemistry from the University of Utah in 2006. He is now a Center for Cancer Nanotechnology Excellence Distinguished Fellow in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.  His first major research focus is the toxicology of nanoparticles, or nanotoxicology. He is also evaluating nanoparticles’ potential as vehicles for oral drug delivery. This work is based on the fact that absorption of nanoparticles into the blood stream could significantly increase the therapeutic payload to a target site.