Abstract: Biological materials are incredibly complex: structural elements are found on many length scales, non-linear elastic effects are common, forces are generated and transmitted on demand, and protein binding/unbinding dynamics give rise to new time scales of material rearrangements. These dynamics not only suppress fatigue, but can allow systems to heal even when loaded to failure. Such materials properties impart tremendous function to biological systems: bacteria divide, cells crawl, and tissues maintain cohesive and adhesive strength to form complex organisms that can withstand substantial force. Yet, our ability to exploit the unique properties of cells and tissues to generate manmade materials with enhanced functionality remains poor.
In this talk, I will discuss my laboratory's efforts to develop a predictive understanding of how molecular architecture and dynamics control the mechanics of biomaterials. Using marine mussels as a model organism, we explore the role of geometry and internal interfaces in controlling biological adhesion. We observe the dynamics of mussel plaques as they debond from glass using a custom built load frame with integrated dual view imaging capabilities. We find that the shape of the holdfast improves bond strength by an order of magnitude compared to other simple geometries and that mechanical yielding of the mussel plaque further improves the bond strength by ~100× as compared to the strength of the interfacial bonds. Moreover, a porous, heterogeneous network within the plaque gives rise to novel modes of load transfer within the material. These experiments provide new insight into the physical origins of biomaterials properties, and suggest new avenues for design of biomimetic systems with enhanced properties.
Bio: Megan T. Valentine received her B.S from Lehigh University ('97), M.S. from UPenn ('99) and Ph.D. from Harvard ('03), all in Physics. She completed a postdoctoral fellowship at Stanford in the Department of Biological Sciences, where she was the recipient of a Damon Runyon Cancer Research Postdoctoral Fellowship, and a Burroughs Wellcome Career Award at the Scientific Interface. In 2008, she joined the faculty at the University of California, Santa Barbara, where she is now an Associate Professor of Mechanical Engineering. Her interdisciplinary research group investigates many aspects of biophysics and biomechanics, from regulation of intracellular transport, to shape control of cell division, to design of novel bioadhesives. In 2013, she was awarded an NSF CAREER Award for her work on neuron mechanics, and in 2015 was awarded a Fulbright Award to study adhesion mechanics in Paris, France. She is an Associate Director of the California NanoSystems Institute, and a co-leader of an IRG on Bio-inspired Wet Adhesion within the UCSB Materials Research Laboratory, and NSF MRSEC.