Fluorescence Polarization (FP)

Fluorescence Polarization (FP)


Screening of small molecule compounds is important in target compound discovery and drug optimization. Currently, several techniques are widely used for small molecule screening. Fluorescence polarization (FP) assay technology is based on the fluorescent nature of the assay and has potential applications as a rapid and stable detection of interactions and binding affinities.

fluorescence polarization (FP) technologyFigure 1. Principle of fluorescence polarization assay. (Zeng H, ei al., 2015)

Working Principle

When a fluorescent molecule is excited by plane-polarized light, the emitted light will lie in the same plane of polarization if the molecule remains stationary during the excitation period. If the molecule is rotated or flipped out of this plane during the excitation period, the emitted light will be in a different plane of polarization than the excitation light. But if the fluorescein is excited with vertically polarized light, the intensity of the emitted light can be detected in both the vertical and horizontal planes of polarization. In the case of a very large molecule, the motion that occurs upon excitation is minimal and the emitted light is polarized to a high degree. Conversely, a small molecule results in rapid rotation or flipping, and the emitted light will be depolarized concerning the excitation plane.


  • No generation of hazardous radioactive waste.
  • Maximizes simulation of living environments, with real-time monitoring and quantification of intermolecular binding or segregation.
  • No need to separate free and bound tracers.
  • High sensitivity and reproducibility.

CD BioSciences possesses professional fluorescence polarization (FP) technology dedicated to providing support for enzymology, molecular interaction studies, and environmental monitoring.

Main Applications

  • Molecular Interaction Research

We offer FP technology for studying intermolecular interactions and detecting selected targets by analyzing differences in the polarization signals of fluorescent molecules in the system. The calculation is based on the positive correlation between the intensity of fluorescence polarization and the content of the substance to be detected. We currently apply FP technology to the study of receptor-ligand, protein-peptide and DNA-protein interactions.

  • Enzymology

The principle of protein kinase activity testing using FP technology is to use fluorescently labeled phosphorylated substrate and protein kinase to catalyze the competitive binding reaction between the phosphorylated substrate and the anti-serine antibody. The polarization value correlates with protein kinase activity and can be used to screen protein kinase inhibitors.

  • Environmental Monitoring

FP technology can detect the presence and concentration of pollutants by labeling specific pollutant molecules and using changes in fluorescence signals. Therefore, we can detect heavy metal ions, pesticide residues, and other harmful substances in water bodies using FP technology. In addition, we can further realize the sensitive and accurate detection of these pollutants by choosing suitable fluorescent markers.

What Can We Offer?

CD BioSciences has a wealth of experience to ensure that our clients are provided with specialized fluorescence polarization (FP) technology. For more details, please feel free to contact us.


  1. Zeng H, Xu W. (2015). Enzymatic assays of histone methyltransferase enzymes[M]//Epigenetic technological applications. Academic Press. 333-361.
For research use only, not intended for any clinical use.
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