Fluorescence correlation spectroscopy

Fluorescence correlation spectroscopy (FCS) performs a fluorescence intensity fluctuation analysis emitted by small molecules and / or particles, in solution and / or in cells. The emitted fluorescence is analyzed in a very small volume of solution where the fluorescence intensity fluctuates due to the Brownian motion of the particles. In other words, the number of particles in the subspace defined by the optical system changes randomly around the average number. FCS is a very sensitive analytical tool because it observes a small number of molecules (nanomolar to picomolar concentrations) in a small volume (~ 1μm3). The analysis provides the average number of fluorescent particles and the average diffusion time, when the particle is passing through space. FCS experiments can be performed on a wide variety of specimens, ranging from material science to biology. Because fluorescent labels come in a variety of colors and can bind specifically to a particular molecule (eg, proteins, polymers, metal complexes, etc.), it is possible to study the behavior of individual molecules. Eventually, both the concentration and the size of the particle (molecule) are determined, both important parameters in many fields of biochemical, biophysical, and chemical research. In cell biology, FCS allows the observation of fluorescently labeled molecules in intact living cells, which represents a new area of "biochemistry in situ or in vivo.