Fluorescence Anisotropy (FA)

Fluorescence Anisotropy (FA)


Fluorescence anisotropy (FA) is a fluorescence spectroscopy technique based on molecular rotation, which is based on the change of the polarization state of a fluorescent molecule during absorption and emission to study the motion or orientation of the molecule in the spatial direction. The dipole orientation of fluorescent molecules can respond to the spatial orientation of target proteins, which can be used to study the structure and dynamics of target proteins in vivo in living cells. Currently, FA has been widely used in the detection of a variety of targets such as proteins, metal ions, small molecules, nucleic acid molecules, etc. Meanwhile, it has also been used to explore the interaction between substances, and it has a wide range of applications in drug research, molecular imaging, and high-throughput screening.

fluorescence anisotropy (FA) technologyFigure 1. Working principle of protein amplifying FA for sensitive detection of small molecules. (Xiao X, et al., 2022)

Working Principle

The main principle of FA is that the degree of anisotropy of a fluorophore is inversely proportional to its molecular rotation speed at constant temperature and solution viscosity. When fluorescent molecules bind or rotate more slowly by diffusion in high-viscosity media, they exhibit higher fluorescence anisotropy; while when fluorescent molecules rotate and diffuse or resonate resulting in energy transfer, the fluorescence anisotropy will be low. By measuring the fluorescence anisotropy values of fluorescent molecules, the binding and dissociation constants between the target and the fluorescently labeled drug can be studied.


  • High sensitivity, flexibility, and scalability.
  • Real-time, dynamic monitoring of fluorescent molecule motion and orientation changes.
  • Multi-channel analysis capability allows effective differentiation of fluorophores with overlapping emission spectra and therefore can be used for multi-channel analysis.
  • Non-invasive, does not damage or interfere with samples.

CD BioSciences has a full range of biophysical technology platforms to ensure the availability of fluorescence anisotropy (FA) technologies to its customers for drug discovery, bioimaging, environmental monitoring, and food safety.

Main Applications

  • Drug Discovery

FA technology plays an important role in the study of drug-biomolecule interactions. We can assess the binding ability, affinity, and dissociation constants of drugs by measuring changes in the fluorescence anisotropy of fluorescently labeled drug molecules bound to target molecules, which in turn accelerates drug design and optimization.

  • Biomolecular Imaging

FA technology can be used for imaging and localization of biomolecules. Through labeling specific biomolecules, such as proteins, nucleic acids, etc., we can observe their distribution, movement, and interactions in cells or tissues, thus revealing the mechanisms of biological processes.

  • Environmental Monitoring and Food Safety

FA can detect harmful substances in water samples, additives or contaminants in food, etc. We can evaluate the type and concentration of contaminants by measuring changes in fluorescence anisotropy values.

What Can We Offer?

CD BioSciences, a leading biophysical technology company, possesses a well-rounded analytical technology platform to provide fluorescence anisotropy (FA) to clients. If you are interested in our services and need more details, please feel free to contact us.


  1. Xiao X, Zhen S. (2022). Recent advances in fluorescence anisotropy/polarization signal amplification[J]. RSC advances. 12(11): 6364-6376.
For research use only, not intended for any clinical use.
Related Services
Get In Touch

CD BioSciences is a biotechnology company focused on biophysical services. We are proficient in both chemistry and biophysics, and have a comprehensive biophysical platform containing a wide range of advanced technologies.

  • Tel:
  • Email: