Talker: Yi Fu，Center for Fluorescence Spectroscopy，University of Maryland  School of Medicine，Baltimore，Maryland，21201

Topic: Plasmonic enhanced single-molecule fluorescence

Time: 2011-07-06 10：00

Address: 317 meeting room, Physics Building

The capabilities of fluorescence technology are fully entrenched into almost all aspects of biological research. To a significant extent future advances in biology and medicine will be dependent on advances in fluorescence technology. There are many examples where future improvements in fluorescence technology will result in improved experimental capabilities. For example, single molecule detection and imaging is limited by the photostability of fluorophores. The ability to detect and track single labeled biomolecules within cells is severely limited by the brightness (detected photons per second) of the probes and their photostability. Detection of even the brightest probes is just at the limits of detection, and modest decreases in brightness, increases in background, or mobility of the fluorophores can render them undetectable. It appears that the chemistry of organic fluorophores is near its limit and dramatic increases in brightness or photostability are not likely. Another example is gene expression and nucleic acid arrays. At present almost all fluorescence experiments are performed using the far-field emission from fluorophores resulting from spontaneous emission. We have developed methods to explore the use of near-field interactions of fluorophores with metallic nanoparticles and nanostructured-surfaces. Excited state fluorophores can interact with these metallic structures to create plasmons, which can be trapped at the metal sample interface and radiate in defined directions. Our studies showed that proximity to metallic nanostructures can greatly increase the rates of radiative decay and thereby improve brightness and photostability of single fluorophores. These effects will result in new classes of experimental procedures, novel probes, bioassays and devices.