Julie Biteen

Department of Chemistry
University of Michigan

Single-Molecule Imaging and Plasmon-Enhanced Fluorescence:Understanding Bacterial Function on the Nanoscale

By beating the diffraction limit that restricts traditional light microscopy, single-molecule fluorescence imaging is a precise, noninvasive way to sensitively probe position and dynamics. We are pioneering super-resolution imaging methods for unraveling important biological processes in live bacteria, and I will discuss how we understood the mechanism of membrane-bound transcription regulation in a pathogen, and revealed an intimate and dynamic coupling between DNA mismatch recognition and DNA replication in a highly conserved repair pathway. Still, the resolution of single-molecule imaging, and thus our ability to understand subcellular dynamics, is limited by the fluorescent probes. Thus, we take advantage of the localized surface plasmon resonances that result from the interaction of light with small metal nanoparticles to improve the brightness and photostability of nearby fluorescent labels. We have measured the fundamental properties of plasmon-enhanced fluorescence with single-molecule detection, and we have discovered how coupling leads to a predictable shift of the emission position. Finally, we are applying this understanding to biocompatible enhancement of fluorescent protein emission, extending the advantages of metal-enhanced fluorescence to live-cell bio-imaging, and creating a flexible technology for high-resolution, real-time imaging.