MS&E Colloquium: Prof. Sandra J. Rosenthal, Vanderbilt University
Date: April 10, 2009 from 2:00 pm to 3:00 pm EDT
Location: Columbia University
Morningside Campus
Interschool Lab - 750 CEPSR
Contact: For further information regarding this event, please contact Chad Gurley by sending email to cg2029@columbia.edu .
Info: Click Here to Visit Website.
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Prof. Sandra J. Rosenthal, Vanderbilt University

Structure-Property Relationships in Functional Nanocrystals: From Single Protein Trafficking to White Light, Solid State Lighting

  

Size tunable optical properties in semiconductor nanocrystals originating from quantum confinement were established by Brus in the mid eighties and are now commonplace, found even in the undergraduate laboratory. Modifications to the structure of the nanocrystal give rise to different properties, and thus different applications. We have pioneered two techniques for structure/composition determination of nanocrystals; 0.7 A resolution, aberration corrected, atomic number scanning transmission microscopy (Z-STEM, or "super-STEM") and Rutherford backscattering spectroscopy. Through an iterative process of synthesis and microscopy we have created core/shell nanocrystals with a near 100% fluorescent quantum yield.  Bright, photo-stable core/shell nanocrystals have size-tunable, narrow emission bands and are revolutionizing biological imaging. We have developed drug-conjugated core/shell nanocrystals that enable the real-time tracking of the serotonin transporter protein (SERT). Neurotransmitter transporter proteins are responsible for the efficient clearance of neurotransmitters from the extracelluar space following release. Transporters are among the most widely and successfully targeted proteins for medication development, most notably the SERT selective reuptake inhibitors (SSRIs), typified by ProzacTM. The multiplexing capability offered by core/shell nanocrystals typifies the paradigm that a different size nanocrystal yields a different emission color.  However, we have found that the emission of ultra-small  nanocrystals spans the entire visible portion of the electromagnetic spectrum, giving a pure white spectrum. As the nanocrystal size is decreased, the emission from the nanocrystals becomes pinned, implicating surface states in the emission. Prototypical LEDs utilizing these ultra-small nanocrystals as a nanophoshor have an extraordinary color rendering index of 93.

Hosted by Prof. Simon Billinge