Fast interactions between Rh6G and dGTP in water studied by fluorescence correlation spectroscopy Original Research Article

The feasibility of fluorescence correlation spectroscopy (FCS) for the monitoring of fast kinetic processes has been investigated. The interaction between Rh6G and different nucleotides in water served as a model system. Following the fluorescence fluctuations arising due to dye-nucleotide interactions around an unperturbed equilibrium it is possible to retrieve information about association and dissociation kinetics of the different electronic states involved in the fluorescence generation. No macroscopic perturbation of thermodynamic parameters, as in chemical relaxation experiments, is needed. Compared to other fluorescence techniques used to study interactions of this kind, such as flash photolysis, FCS requires a very simple instrumentation. A very broad time interval can be covered and the fact that FCS is based on a fluorescence microscope allows for kinetic studies on a microscopic scale. Hence, FCS can be used in parallel or as an alternative to more established fluorescence techniques providing a simple and easy-to-use tool by which similar and complementary information on kinetic processes can be obtained.