Biophysical Society Thematic Meeting | Tutzing 2026

Single-Molecule FRET: The Next 30 Years

Poster Abstracts

29-POS Board 15 FROM PERRIN TO FÖRSTER: BRINGING RESONANCE ENERGY TRANSFER INTO THE CLASSROOM Tom Kache 1 ; Maria Dienerowitz 1 ; 1 Ernst Abbe University of Applied Sciences, SciTec, Jena, Germany Exactly one hundred years ago, in 1926, Francis Perrin demonstrated that fluorescence polarization reveals molecular rotation. Molecules with specific structure preferentially interact with light of matching polarization. In viscous solution, when molecular rotation is slow compared to the fluorescence lifetime, this polarization is preserved in the emission. Building on Perrin's work, Feofilov and Sveshnikov observed that this polarization disappears at high fluorophore concentrations. These experiments led to the development of the theory of resonance energy transfer by Theodor Förster in 1948, forming the foundation of modern FRET-based biological research. While state-of-the-art FRET experiments are highly specialized and use sophisticated technology, the original observations can be recreated in classrooms with easily accessible equipment. We propose a two-part experiment using a handheld diode laser, filter and polarizer sheets, and a smartphone camera. First, students observe increasing fluorescence polarization with increasing glycerol concentration in water, recreating Perrin's observations that demonstrate viscosity-dependent molecular rotation. Second, in 70% glycerol:water, they observe the concentration depolarization effect with increasing fluorophore concentration, introducing resonance energy transfer through experimental observation rather than theory. These accessible experiments demonstrate macroscopically observable molecular dynamics in classroom and undergrad lab settings, introducing concepts of molecular dynamics as they were originally discovered: through curiosity-driven basic research. These experiments also demonstrate to students the interdisciplinary nature of science, combining knowledge of chemistry, physics of light, mathematics, and technology to gain fundamental insights into the natural world. These experiments bring students into first contact with fundamental concepts of molecular dynamics and resonance energy transfer through hands-on discovery. They increase public awareness of modern FRET research and inspire the next generation of FRET scientists.

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