When using fluorescence intensity as a method, the measurement values are directly proportional to the concentration of the fluorescent dye that is used in the assay. A good example is with fluorescence based DNA measurements such as PicoGreen®, the measurement values are directly proportional to the concentration of DNA. For fluorescence polarization, the resulting value is related to the molecular size of the fluorescent dye. Fluorescence polarization is a very useful method for binding studies where a small molecule is tagged and then binds to a larger molecule, e.g. in GPCR-signaling pathways to investigate ligand receptor affinities. Both methods need a fluorescent dye to work. Another example assay platform of these differences can be seen with the Transcreener® ADP2 assay from BellBrook Labs, one uses fluorescent polarization and another uses fluorescent intensity.
For more information about fluorescence intensity or fluorescence polarization assays, please look at BMG LABTECH´s Optic Module technology page to find the optimal filters or Optic Modules for your assay.