Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 26: Poster Session II

BP 26.24: Poster

Thursday, March 29, 2007, 17:00–19:30, Poster B

Fluorescence-Emission Control of Single CdSe-Nanocrystals using Metal-Modified AFM Tips — •Volker Walhorn, Olaf Schulz, Heinrich Frey, Christoph Pelargus, Dario Anselmetti, and Robert Ros — Experimental Biophysics, Physics Department, Bielefeld University, Germany

The concept of fluorescence switching and modulation due to local energy transfer is of increasing importance in nanobiophysics. Assays taking benefit from fluorescence quenching or fluorescence resonant energy transfer (FRET) between individual nanoobjects are currently evolving and facilitate fascinating possibilities for investigating matter at the nanoscale. We have established a setup combining total internal reflection microscopy (TIRFM) and atomic force microscopy (AFM) in order to do simultaneous laser induced fluorescence imaging and manipulation on the single molecule level [1]. As fluorophores we chose semiconductor nanocrystals (quantum dots) since they show high resistance to photo-bleaching. The quantum dots were addressed with metal functionalized AFM probes while simultaneously measuring the fluorescence-emission. We could not only switch a single fluorophore from the emitting state to the quenched but also observe distance dependent enhancement of fluorescence intensity due to exciton-plasmon coupling. In future force spectroscopy experiments we will use appropriate labeled ligand-receptor complexes, proteins or nucleic acids to reveal supplementary information of inter- or intramolecular dynamics. [1] R. Eckel, V. Walhorn, Ch. Pelargus, J. Martini, J. Enderlein, Th. Nann, D. Anselmetti, and R. Ros; Small (in press).