Multiresponsive\nLiquid Crystal Collagen Guides Mussel\nByssus Formation

Marine mussels fabricate tough collagenous fibers known\nas byssal\nthreads to anchor themselves. Threads are produced individually in\nminutes via secretion of liquid crystalline (LC) collagenous precursors\n(preCols); yet the physical and chemical parameters influencing thread\nformation remain unclear. Here, we characterized the structural anisotropy\nof native and artificially induced threads using quantitative polarized\nlight microscopy and transmission electron microscopy to elucidate\nspontaneous vs regulated aspects of thread assembly, discovering that\npreCol LC phases form aligned domains of several hundred microns,\nbut not the cm-level alignment of native threads. We then explored\nthe hypothesized roles of mechanical shear, pH, and metal ions on\nthread formation through <i>in vitro</i> assembly studies\nemploying a microfluidic flow focusing device using purified preCol\nsecretory vesicles. Our results provide clear evidence for the role\nof all three parameters in modulating the structure and properties\nof the final product with relevance for fabrication of collagenous\nscaffolds for tissue engineering applications.