Cellular life is a non-equilibrium phenomenon that requires the coordinated spatio-temporal organization of signaling networks and cellular structures. A prime example is cellular membranes: fluid lipid bilayers that together with their associated proteins define the cell compartments and serve as a bio-reactive surface for signal processing and transduction across the membrane. Reflecting the membran's important role in cellular organization are the many diseases inherently related to malfunctions of membrane associated processes.

           The goal of our group is to quantitatively understand how membrane configuration, i.e. location and chemical identity of membrane components dynamically responds to and feeds back into biochemical regulation. To that end we study in vitro and in vivo membranous systems by combining methods from physics, chemistry, biology and material sciences. A particular strength of the group is the use and development of advanced optical techniques such as multicolor total internal reflection (TIRF) microscopy, single molecule tracking and multicolor fluorescence cross-correlation spectroscopy (FCCS). In order to quantitatively understand the bidirectional relationships between membrane dynamics and biological function, the research in our group integrates the following areas:

           Systems that model biological membranes offer unsurpassed control over physicochemical properties such as composition, packing density or lateral pressure. In addition, environmental parameters can be experimentally adjusted, thus providing an avenue to study membrane physical and biochemical phenomena in a rigorous manner. Previously, model membrane system studies have almost exclusively focused on thermodynamically equilibrated situations. Thus, dynamic phenomena in non-equilibrium conditions, such as temporal and spatial patterns of molecule distributions - a hallmark of cellular life- remain mostly unexplored Using well controlled biomimetic systems, we study physical phenomena of membranes as they arise in non-equilibrium conditions. Of particular interest are the interrelationships between patter-forming processes and biochemical reactions. In combination with analytical and numerical models, studies of such simplified, modular systems permit the concise description and quantitative understanding of the underlying physicochemical principles. Besides basic scientific aspects, we are also working on utilizing our insights in developing "smart" or adaptive biomaterials that dynamically interact with their environment.

           Today's paradigm of the plasma membrane of eukaryotic cells as a complex, heterogeneous two dimensional fluid with structures on many time and length scales is by now well established. However, relatively little is still known about the dynamic coupling between membrane organization and other cellular functions, such as large scale remodeling of the cell surface, specificity of aggregation, stabilization of supra-molecular protein clusters, directed translocation processes or dynamic reorganization of the cytoskeleton. We investigate the mechanisms that couple membrane structure and biological functions in the full context of cellular life by studying, in live cells, the dynamic response of membrane organization to perturbations in the environment.

           In order to probe dynamics in biological systems, experimental techniques must be compatible with the narrow range of environmental conditions (aqueous milieu, temperature, pH etc.) within which cellular life exists. This inherent limitation has made light based techniques, which are biocompatible and minimal invasive, one of the most prolific tools for biophysical experimentation to date. An essential research effort in our group focuses on developing novel optical tools for biophysical research. The goal is to extend the accessible spatial and temporal scales and the list of physical and chemical properties that can be experimentally queried with light based techniques.