Biopolymers Out-of-Equilibrium: Insights from Blood Clotting
Prof. Alfredo Alexander-Katz, Massachusetts Institute of Technology
The dynamics of biopolymers under out of equilibrium conditions plays a crucial role in biology. In particular, the dynamics of biopolymers in flow, and how flow affects its conformation plays an important role in multiple processes. Conversely, by studying such dynamics it is possible to learn many physical properties of the underlying biopolymers themselves. In this talk we will focus on a large biopolymer found in blood, the so-called von Willebrand Factor (VWF), which is crucial to stop bleeding. We will explore theoretically and experimentally the behavior of VWF starting from the single chain perspective and ending with large reversible cell-biopolymer aggregates that become the plug that prevents further blood loss. VWF displays a rich and many times counterintuitive variety of behaviors by using an exquisite combination of self-interactions that compete with interactions with other proteins, which allows it to tune the unfolding response to flow, adhere above to surfaces above a certain stress, and form reversible shear-responsive aggregates with platelets. In summary, the biophysics VWF is rich in the area of mechanobiology and has led to major new discoveries in the area of vascular diseases, polymer biophysics, and drug delivery. It also has the potential to form the basis of novel materials that display some of the properties of the naturally occurring ones for uses in medical and technological applications.