Biological cells regulate their mechanical behavior through the cytoskeleton, a composite network of interacting protein filaments whose properties emerge from structure and dynamics across multiple scales. In this talk, I will describe optical tweezers microrheology and imaging studies of cytoskeletal composite and motor-crosslinked networks, highlighting how network composition, ionic environment, and structural reorganization shape viscoelastic and nonlinear mechanical responses. These experiments reveal how competing interactions and multiscale organization enable cytoskeletal networks to support diverse and adaptable mechanical functions, offering insight into how cells tune their mechanical state in response to internal and external cues.
Dr. Bekele Gurmessa earned his B.S. and M.Sc. in Physics in Ethiopia, then pursued doctoral studies at North Dakota State University, where he specialized in soft matter physics. He then conducted postdoctoral research at the University of San Diego, California, focusing on experimental biophysics using advanced techniques, including optical trapping and fluorescence microscopy. Dr. Gurmessa is currently an Assistant Professor in the Department of Physics and Astronomy at Bucknell University. His research investigates the mechanics, organization, and structural dynamics of cytoskeletal systems. Using tools including optical tweezers, microrheology, microfluidics, and confocal fluorescence microscopy, his work aims to understand how molecular-scale interactions give rise to the mechanical properties and behavior of living cells.