Levich Institute Seminar Announcement, 03/16/2010
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Alejandro Rey
Department of Chemical Engineering
"Liquid Crystal Models of Biological Materials and Processes"
Liquid crystal phases are found in DNA, proteins, lipids and polysaccharides. Frozen-in, chiral liquid crystal ordering also occurs in solid biocomposites such as insect cuticle, muscle, plant cell walls and collagen, where the helicoid structure is believed to arise by self-assembly processes. Spinning of silk fibers by spiders is another biological polymer process that relies on liquid crystal dynamic self-assembly. I will discuss the progress and challenges of modeling in three such applications:
(1) Characterization of structure and flow of liquid crystal collagen and DNA solutions. Theory and simulation based on liquid crystal flow, elasticity and interfacial models show how long range orientational order under flow conditions results in pattern formation processes that can be used to identify and characterize these materials.
(2) Biological helicoids form by directed self-assembly. Theory and computer simulation of chiral phase ordering show that the directed self-assembly process reproduces the natural structures. The computational results shed light on the role of chiral ordering on the formation of helicoidal monodomains.
(3) Spinning of spider silk involves a complex sequence of phase transitions that includes nematic phase ordering in the duct section of the spinning apparatus. Simulation of phase ordering under capillary con?nement replicates the observed structures found in Nephila clavipes and other orb-weavers. The computational results shed light on the role of defect textures in the fiber spinning process.