Solution-phase single molecule quantum dot fluorescence resonant energy transfer

COLL 402

Hedi Mattoussi, hedimat@ccs.nrl.navy.mil, Optical Sciences Division, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, Thomas Pons, Optical Sciences Division, Code 5611, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, Igor L. Medintz, imedintz@cbmse.nrl.navy.mil, Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, Xiang Wang, xiangw@Glue.umd.edu, Department of Chemistry & Biochemistry, University of Maryland, College Park, MD MD 20742, and Douglas English, denglish@mail.umd.edu, Department of Chemistry and Biochemistry, University of Maryland, Bldg 091, College Park, MD 20742.
Due to their unique optical properties semiconductor CdSe-ZnS core-shell quantum dots (QDs) offer several advantages in fluorescence resonant energy transfer (FRET) applications. Here, we present a single particle FRET (spFRET) study of freely diffusing QD sensing assemblies, composed of self-assembled QDs donors and dye-labeled protein acceptors. In particular, we show that while ensemble measurements yield average FRET efficiency and information on donor-acceptor separation distance, spFRET offers additional insights into the heterogeneity of FRET efficiency distributions. We first demonstrate that the self-assembly process leads to a Poisson distribution of the number of protein-dye per QD, and show that there is direct correlation between spFRET and ensemble measurements. We then apply spFRET to characterize a QD-bioreceptor sensor specific for the sugar maltose. Our data allow us to determine how the proportion of QDs bound to maltose varies with the maltose concentration and provide a binding constant that is consistent with ensemble measurements.
 

Advances in Nanomedicine
8:30 AM-12:00 PM, Tuesday, 12 September 2006 Sir Francis Drake -- Monterey/Cypress Rooms, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006