Quantum dots are light-emitting nanocrystals that have emerged as a new class of fluorescent label for molecular and cellular imaging. These particles have unique optical and electronic properties that enable long-term multicolor imaging with exceptional sensitivity, down to the level of single molecules. Quantum dots have a multicomponent structure consisting of inorganic crystalline domains, organic ligands and polymers, and biomolecules, each of which can be independently engineered to modulate optical, physicochemical, and biological properties for specific applications. This seminar will describe strategies for engineering their properties for implementation as single-molecule probes in complex biological systems where nonspecific interactions, hindered diffusion due to macromolecular crowding, and oxidative degradation are problematic. We use these nanocrystals to image plasma membrane receptor dynamics in living cells at the single-molecule level, and to image nanoparticle-mediated drug delivery in solid tumors at the sub-cellular level. Importantly, we can specifically tune the wavelengths of these particles to allow multispectral imaging with transgenically expressed fluorescent proteins for simultaneous observation of cellular biology and cell-type identification.

Dr. Smith received a B.S. in Chemistry in 2002 from the Georgia Institute of Technology. As an undergraduate he worked in the research labs of Dr. Robert Nerem, Dr. Athanassios Sambanis, and Dr. James Powers in vascular tissue engineering, cellular gene delivery, and targeted molecular imaging agent development. He then received a Ph.D. in Bioengineering in 2008, also from the Georgia Institute of Technology, while working with Dr. Shuming Nie toward the design of nanoparticles for the detection and treatment of cancer. In 2008 he began a postdoctoral position as a Distinguished Fellow of the Emory University/Georgia Tech Center for Cancer Nanotechnology Excellence (CCNE), focusing on single molecule imaging in living cells using quantum dots. Dr. Smith is now at the University of Illinois at Urbana Champaign's Bioengineering department where he develops new nanomaterials for studying cancer biology. He is particularly interested in nanoparticles called quantum dots, fluorescent crystals that can be used to image cancer-related cellular events at the microscopic level of individual molecules. By combining these particles with new transgenic animal models of cancer and a variety of imaging and microscopy techniques, he aims to understand fundamental molecular mechanisms of tumor development which will lead to a new generation of cancer treatments.