What factors can influence FRET efficiency?

The efficiency of FRET is closely dependent on several factors including: the Forster distance (R0), the physical distance between the donor and acceptor molecules, overlap of spectrum, and orientation of the dipoles. The overlap between the emission spectrum of the donor and the absorption spectrum of the acceptor is crucial. This overlap enables the energy transferred from the excited donor to the ground state to excite the acceptor, a process known as resonance. Essentially, the more overlap between the spectra, the more effectively the donor can transfer energy to the acceptor. The efficiency of resonance energy transfer is influenced by the alignment of the donor's emission transition dipole and the acceptor's absorption dipole. The K2 value quantifies this interaction between the two dipoles. Additionally, FRET is successful only when the distance between the donor and acceptor molecules is less than 10 nanometers. Lastly, a large Forster distance indicates that energy transfer between the donor and acceptor molecules can occur over a relatively long distance and thus results in a high FRET efficiency.