Electron multiplying charge-coupled device camera based fluorescence correlation spectroscopy.

A fluorescence correlation spectroscopy (FCS) setup is built with an electron multiplying charge-coupled device camera. Although the instrument has a limited time resolution of 4 ms, compared to 0.1-0.2 mus for common instruments using avalanche photodiodes, it allows multiplexing of FCS measurements, has a software-adjustable pinhole after data collection, performs flow speed as well as flow direction measurements in microchannels and could be used to do spectral FCS. Measurements are performed on fluorescent dyes and polystyrene beads in high-viscosity media and on epidermal growth factor receptors in Chinese hamster ovary cells. Using real measurements on single spots, multiplexing of focal spots and detection elements are simulated and the results are discussed.