FCS Application: Concentration Mapping

The combination of FCS and APD (Avalanche Photo Diode) imaging provides a fast and efficient way to map concentrations in a cell or another structure.

FCS measurements are point measurements. They deliver local information about single spots within the sample. To get concentration information over a hole image, FCS and APD imaging can be combined using the same detector. This enables scientist to calibrate the APD image intensity by the particle number obtained from the FCS measurement. In this way expression levels which are displayed as an image intensity can be quantified.

The acquisition of concentration mapping is well supported in the SMD FCS wizard.

Example: Concentration mapping of TiF1a-GFP in HeLa cells. The calibration of APD image was performed with FCS point measurement. ROIs for FCS measurements are shown as black crosses. The concentration was calculated from autocorrelation curves (red and blue graphs). A spatial map of intracellular concentrations is obtained. The correlation curves yield information about the particle motility at the measured points.

We thank Dr. Matthias Weiss, Dr. Jedrzej Szymanski, and Nina Malchus, DKFZ, Heidelberg, Gemany

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