The following sections describe the advantages that make Fluorescence Correlation Spectroscopy (FCS) an ideal technique for measuring and assaying molecular interactions.
For a comparison of the advantages and disadvantages of FCS, ELISA, and PCR, see FCS vs. Conventional Bioassays (ELISA & PCR)
The interaction and complexing of biomolecules is fundamental to biological functions. Important examples of molecular interactions include:
These interactions and binding events are extremely specific to the particular molecules involved and, as a result, the high specificity and selectivity of these interactions can be used to form the basis of biochemical assays. Biochemical assays utilize specific biomarker probes to identify and measure the presence of specific target molecules (e.g., an enzyme probe against the target glucose molecule will bind only glucose, not other sugars).
All of the following industries involve research of molecular interactions:
Even in its simplest form, autocorrelation mode, Fluorescence Correlation Spectroscopy (FCS) provides a highly flexible, easy-to-use assay format. These properties of FCS measurements make it an incredibly convenient assay method:
Most techniques for measuring molecular interaction are intensity-based, which means that they measure the average intensity of a sample, and therefore the average amount of an assay probe without distinguishing bound from unbound material. In contrast, FCS is a nonaveraging technique, offering simultaneous measurement and distinction of bound and unbound fractions. As a result, FCS:
When operated in cross-correlation mode, FCS offers the possibility of assaying interactions of multiple targets simultaneously. These properties of cross-correlation assays introduce significant advantages to FCS-based assays: