Measurement of molecular interactions using Fluorescence Correlation Spectroscopy (FCS)
FCS is a single molecule technique that measures the fluorescence intensity fluctuations as fluorescent molecules diffuse into and out of a small (femtoliter) volume. Statistical analysis of fluorescence-intensity fluctuations results in an autocorrelation curve that shows the decay of temporal correlation in fluorescence intensity over time.
FCS can be used to measure interactions of fluorescently labeled molecules with binding partners that result in a change in the diffusion time. The staff in the PCL is currently using the QuantumXpert FCS instrument from Sensor Technologies. Their effort to date has focused on developing new methods to analyze FCS data using the dye Alexa 488 as a model molecule. In addition they have begun to analyze antigen/antibody interactions using FCS.