| Abstract
| - Collagen is a major component of the extracellular matrix that exhibits unique hierarchical organization at multiplelength scales ranging from nano to macroscale. Despite numerous methods to create collagen-based biomaterials, theself-assembly process of collagen ex vivo is poorly understood. Here, we describe a system that uses a microfluidicmethod to investigate the dynamics of collagen self-assembly. A main inlet stream of semidilute soluble collagen-Iis hydrodynamically focused by two side inlet streams, which gradually increases the pH in the main stream. Thisenables dynamic nonequilibrium investigation of the self-assembly process simultaneously at different positions andtherefore different stages in the assembly process within the same system. The device is designed for in situ monitoringand characterization of collagen assembly using polarization microscopy and X-ray diffraction: the continuous extensionalflow provides highly ordered phases of the macromolecules over a large distance in the outlet microchannel and allowsfor data collection without material damage. We further demonstrate that finite element method simulations providea good description of our experimental results regarding the diffusive phenomena, flow profile, and pH distribution.Our approach has broad impact, since it provides a powerful means of controlling and investigating the dynamicself-assembly process of biomacromolecules.
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