Characteristics of von Willebrand Factor multimer adhesion and its bio-inspired applications

The von Willebrand Factor (vWF) is a large multimeric protein that aids blood clotting. Hydrodynamic force triggers elongation of vWF; this regulates its activity by exposing binding sites for platelets and collagen. To investigate mechanisms of vWF multimer adhesion to relevant biological entities, a coarse grain molecular model is used to explore vWF interaction with collagen-coated surfaces. The vWF multimer model incorporates observed mechanical properties of vWF monomers in that the model A2 domain in each monomer is capable of significant elongation with sufficient applied force on the molecule. Brownian dynamics simulations have been performed to understand a single vWF multimer adhesion process in both free-draining and hydrodynamic interactions (HI) cases. Results show the configuration at the moment of adhesion is critical, as this dictates the configuration of vWF thereafter. The presence of the collagen-coated surface increases the stretching of vWF multimers and the elongation of model A2 domains. HI effect plays a hindering role in unfolding of vWF multimer and elongation of model A2 domains. The adhesion is impeded by HI, and results in hydrodynamic lift leading to vWF multimer migration away from the wall.