Försterresonansenergiöverföring

Försterresonansenergiöverföring, often abbreviated as FRET, is a non-radiative energy transfer mechanism that occurs between two light-sensitive molecules, a donor and an acceptor. This process is dependent on a dipole-dipole interaction and is sensitive to the distance between the donor and acceptor molecules. FRET is often described as a "molecular ruler" because its efficiency decreases sharply with increasing distance. Specifically, the energy transfer efficiency is proportional to the inverse sixth power of the distance between the donor and acceptor.

The donor molecule, upon excitation by light, can transfer its excitation energy to the acceptor molecule if the emission spectrum of the donor significantly overlaps with the absorption spectrum of the acceptor. This transfer occurs without the emission of a photon by the donor, hence it is a non-radiative process. The acceptor molecule, after receiving the energy, can then de-excite by emitting its own fluorescence, or by other relaxation pathways. The efficiency of FRET is typically quantified by the Förster distance, R0, which is the distance at which the energy transfer efficiency is 50%.

FRET has found widespread applications in various scientific fields, particularly in biophysics and biochemistry. It is used to study molecular interactions, conformational changes in proteins and nucleic acids, and to measure distances within biological systems. By attaching fluorescent donor and acceptor molecules to specific sites on biomolecules, researchers can monitor binding events, protein folding, and enzyme activity. FRET is also employed in the development of biosensors and imaging techniques for cellular and molecular analysis. The sensitivity of FRET to distance makes it a powerful tool for probing nanoscale interactions.