BIOPHYSICS SEMINAR<br>The Krimm Lecture<br>Single-Molecule Spectroscopy and Imaging: 3D Nanoscopy and Biomolecular Dynamics</br>
Since the first optical detection and spectroscopy of a single molecule in a condensed phase host in 1989, a wealth of new information has been obtained from time-dependent measurements and single-molecule probability distributions. When single-molecule labels acting as tiny nanoscale light sources are combined with active control of the emitter concentration, enhanced spatial resolution well beyond the optical diffraction limit can be obtained for a wide array of biophysical structures in cells. Single-molecule emitters also provide precise and accurate 3D position as well as orientation when combined with a double-helix point spread function polarization microscope. If high-resolution spatial information is not needed, a machine called the Anti-Brownian ELectrokinetic trap provides real-time suppression of Brownian motion for single molecules in solution. By extracting multiple parameters from each molecule, this device has been used to explore the detailed dynamics of photosynthetic antenna proteins, multisubunit enzymes, redox enzymes, and single fluorophores.