Stowers Microscopy Center: Fluorescence Correlation Spectroscopy (FCS)

URL

http://research.stowers-institute.org/microscopy/external/Technology/FCS/index.htm

Description

Fluorescence Correlation Spectroscopy (FCS) probes molecular diffusion and interaction. It works best with nanomolar concentrations of protein. Typical experiments involve sample volumes as low as a few microliters. The measurements can be performed in solution and living cells.

FCS is a statistical method. It is based on the analysis of fluorescence fluctuations. Typically, they originate form Brownian motion of dye labeled molecules through a small laser spot. The mean time these molecules stay within the laser spot depends on their size. If a small, dye tagged molecule binds to a larger one, it slows down and emits photons for a longer time during its diffusion through the laser spot.