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BP: Fachverband Biologische Physik

BP 26: Posters II

BP 26.22: Poster

Thursday, February 28, 2008, 17:00–19:30, Poster A

Two-focus fluorescence correlation spectroscopy with an EMCCD detector — •Markus Burkhardt, Jonas Ries, and Petra Schwille — Biophysics/ BIOTEC/ TU Dresden, Tatzberg 47-51, 01307 Dresden, Germany

Fluorescence Correlation Spectroscopy (FCS) extracts thermodynamic and kinetic parameters from time dependent fluorescence intensity fluctuations of labeled biomolecules in solution. In a standard FCS setup, the fluorescence signal is collected from one specific focus position and detected by a single photon sensitive point detector. Two-focus FCS is based on the information from two spatially fixed laser foci. It enhances the precision of diffusion coefficient determination by evaluating the spatial cross-correlation.

Spatially resolved detection, employing an electron multiplying CCD (EMCCD) camera, is a versatile method perfectly suited for two-focus FCS measurements. The distances between the two laterally shifted focal volumes can be changed easily and they can be determined accurately by imaging a microscopic ruling.

We demonstrate two-focus FCS measurements for different fluorescent molecules and under various measurement conditions.