Professor of Chemistry
Adjunct Professor of Physics
Associate Dean for Research Activities
Ph.D. Princeton University, 1995
(Biophysics and Physical Chemistry)
Cells are surrounded by an outer wall or “plasma membrane” composed of proteins and lipids, including phospholipids and cholesterol. The Keller group investigates inhomogeneous distributions of lipids within membranes that model cell membranes.
Recent publications from the Keller group describe miscibility phase transitions in lipid bilayers of giant unilamellar vesicles, and also in surfactant monolayers at an air-water interface. Foundational work in the Keller group has included mapping phase diagrams and tie-lines in these systems. More recently, group members have tracked domain diffusion, observed induction of domains from one leaflet to another in asymmetric membranes, and demonstrated that composition fluctuations in membranes near critical points follow scaling behavior consistent with the 2-D Ising model. Please contact the lab to learn more about projects currently underway (clicking on the links for “selected publications” or “research group” leads to publications by Keller group members.)
To tackle this interdisciplinary subject, group members come from a range of backgrounds, including physical chemistry, bioengineering, physics, and biophysics. The University of Washington strongly enables students in one department to conduct their thesis work in another department. Graduate student work in the Keller group has been rewarded by fellowships from the UW Nanotechnology Program and the UW Molecular Biophysics Training Grant. Group members have won the Biophysical Society’s Student Research Achievement Award, the UW Graduate School Distinguished Dissertation Award, the UW Karrer Prize in Physics, the UW Rabinovitch Fellowship, the NATO Biophysics Summer School’s Poster Competition, and multiple travel awards.
Work in the lab is problem-driven rather than technique-driven, so group members acquire whatever skills are necessary. Data is evaluated by employing conceptual tools of physical chemistry and condensed matter physics, such as self-assembly, miscibility, phase transitions, critical points, and diffusion. Aside from lipid domains, other subjects that the group studies include other self-assembling biomimetic systems such as surfactant micellar solutions, supported bilayers, and membranes containing polymer-lipids or nonlinear optical materials.
Recent work has mainly used the technique of fluorescence microscopy, augmented by self-assembly and microfabrication. The group uses the UW Chemistry NMR facility, the UW Nanotechnology User Facility, and the Washington Technology Center. Collaborations with other groups have contributed additional expertise in x-ray diffraction, NMR, electron microscopy, lipid extraction, chromophore synthesis, and the biochemistry of cell signaling. At this time, the group supports no members who conduct solely theory or simulation work.
T. Portet, S.E. Gordon, and S.L. Keller, Increasing Membrane Tension Decreases Miscibility Temperatures, an Experimental Demonstration via Micropipette Aspiration, Biophys. J., 103, L35-37, 2012. (Featured article)
"REVIEW: An Introduction to Critical Points for Biophysicists" A.R. Honerkamp-Smith, S.L. Veatch, and S.L. Keller, Biochim. Biophys. Acta. (Invited), (2009), 1788, 53-63.
“Tuning Lipid Mixtures to Induce Domains across Leaflets of Unsupported Asymmetric Bilayers”, M.D. Collins and S.L. Keller, PNAS (2008), 105, 124-128.
"Diffusion of Liquid Domains in Lipid Bilayer Membranes", P. Cicuta, S.L. Keller, and S.L. Veatch, J. Phys. Chem. B. (2007), 111, 3328-3331.
REVIEW: “Seeing Spots: Complex Phase Behavior in Simple Membranes,” S.L. Veatch and S.L. Keller, Biochim. Biophys. Acta (Invited), (2005), 1746, 172-185.