UC Berkeley

Cell membranes organize and regulate a vital share of biological signaling. Fluorescence has become the main analytical tool with which to study such systems, and novel fluorescence techniques drive biological discovery at ever-smaller size and time scales. By exploiting the unique photophysics of fluorescent probes, I have advanced two parallel approaches to studying membrane systems: nanoengineered biointerfaces and time-resolved spectroscopy. Metallic nanostructures were engineered to precisely localize fluorescence emission, enhance label-free detection of lipid-protein interactions, and manipulate the diffusion landscapes of supported lipid bilayers. A platform for fluorescence spectroscopy at sub-nanosecond resolution combines fluorescence cross-correlation spectroscopy (FCCS) and time-resolved fluorescence anisotropy (TRFA) to characterize protein diffusion. These techniques have provided insight into the organization and structural flexibility of intercellular adhesion molecule-1 (ICAM-1), oligomerization of the small GTPase H-Ras, and the association of diverse lipid anchor domains in vitro and in vivo. Finally, I demonstrate progress toward single-molecule characterization of lipid-protein systems, and elaborate on its relevance to environmental biosensors for public health and biosecurity applications.