Direct Observation of Fiber Dynamics in Fibrin Networks Under Shear

Abstract

A blood clot stems the flow of blood in response to injury. Fibrin fibers form a network that constitutes the underlying structure of the blood clot. This network imparts its mechanical properties onto the clot itself allowing it to withstand the large range of stresses present in the body. From a materials perspective, many of the mechanical properties of fibrin networks are unusual. In particular, as they are subject to increasing strain, their shear stress increases non-linearly and their normal stress is increasingly negative. Little is known about how fiber dynamics and deformations lead to these properties in fibrin and other stiff biopolymer networks. We image fluorescently labeled fibrin networks under shear using confocal microscopy. Using this data we track individual fibers throughout the network. We report on overall and local non-affinity of fibers, strain in individual fibers and buckling as a function of shear. We do this at various protein and calcium concentrations.