Stanford EE

Light and Single Molecules: From Spectroscopy in Solids, to Super-Resolution Imaging in Cells, Nanocontainers in Solution, Plus a Little Stimulated Emission

Prof. W. E. Moerner (Stanford)
Spilker 232

ABSTRACT: The optical detection of single molecules has provided a new view into the nanoscale. It is fascinating to recall that the early work at IBM Research in the late 1980s arose from low temperature studies of novel optical storage ideas. Since ensemble averaging is removed, each single molecule can act as a reporter of not only its position or wavelength, but also local information about the nearby environment. One key application of single-molecule fluorescence imaging combined with emitter sparsity produced by a variety of mechanisms has been super-resolution microscopy, which enables biological objects and material structures to be observed with resolutions down to tens of nm and below. Examples range from protein bands in axons to details of the shapes of amyloid fibrils, cell surface sugars, protein superstructures in the primary cilium, and much more. This talk will focus on three areas. Recent super-resolution imaging of viral RNA and viral proteins for SARS-CoV-2 infecting mammalian cells shows an amazing array of clusters and association patterns, suggesting the presence of viral RNA replication organelles. For single proteins and biomolecular containers in solution at room temperature, our microfluidic trapping device designed to suppress translational Brownian motion by closed loop electrokinetic feedback has been enhanced by the addition of optical detection of position by interferometric scattering. This device, the ISABEL trap (for Interferometic Scattering-based anti-Brownian ELectrokinetic trap), has been utilized for exploration of individual carboxysomes, small protein nanocontainers in bacteria which enable carbon fixation by rubisco. In a different type of optical study, we have experimentally addressed the question of whether or not a molecule in an electronic excited state undergoing stimulated emission has off-axis dipole character in its emission pattern - the answer is no.

Biography: W. E. (William Esco) Moerner, the Harry S. Mosher Professor of Chemistry and Professor, by courtesy, of Applied Physics at Stanford University, conducts research in physical chemistry and chemical physics of single molecules, single-molecule biophysics, super-resolution imaging and tracking in cells, and trapping of single molecules in solution. His interests span methods of precise quantitation of singlemolecule properties, to strategies for three-dimensional imaging and tracking of single molecules, to applications of single-molecule measurements to understand biological processes in cells, to observations of the photodynamics of single photosynthetic proteins and enzymes. He has been elected Fellow/Member of the NAS, American Academy of Arts and Sciences, AAAS, ACS, APS, and OSA. Major awards include the Earle K. Plyler Prize for Molecular Spectroscopy, the Irving Langmuir Prize in Chemical Physics, the Pittsburgh Spectroscopy Award, the Peter Debye Award in Physical Chemistry, the Wolf Prize in Chemistry, and the 2014 Nobel Prize in Chemistry.