New laser linkage material will improve biomedical diagnostics

Förster resonance energy transfer (FRET) is a process by which energy is transferred between two light-sensitive molecules. Upon receiving energy from an optical energy source, a donor molecule becomes excited and subsequently transfers a fraction of that energy to an acceptor molecule, which then emits light.

If the FRET process is sufficiently efficient, this biomolecular system will generate laser light when it is placed into an optical cavity. Few FRET lasers have existed until recently, but they are well suited for biomedical diagnostics.

For FRET to work efficiently, the distance between the donor and acceptor particles must be fixed by a linkage material. To this end, Rivera et al. adopted the streptavidin-biotin bond, known to be one of the strongest among biomolecules, which is robust and insensitive to temperature.

“The efficiency for transferring energy from the donor to the acceptor drops as one over the distance between them to the sixth power,” said co-author J. Gary Eden. “The primary reason we developed this new type of FRET laser is that the streptavidin-biotin complex holds the acceptor to the donor at a fixed, short distance so as to consistently realize a high energy transfer efficiency.”

The team connected gold nanoparticles to the streptavidin-biotin conjugate to serve as the acceptor in a hybrid structure.

“We would like to progress to more sophisticated nanosystems (as the acceptor), such as nanoantennae, to control the directionality of laser emission,” said Eden. “We also expect to develop nanoscale optics that will become an integral part of the donor-acceptor pair.”

Source: “Fluorophore-gold nanoparticle FRET/plasmonic lasers with the streptavidin-biotin complex as the acceptor-donor linkage,” by J. A. Rivera, K. V. Desai, and J. G. Eden, AIP Advances (2021). The article can be accessed at https://doi.org/10.1063/5.0068168 .