Imaging Methods for Polysaccharide Material Network Structure

Polysaccharide biopolymers in the extracellular space form ubiquitous, diverse biomaterials such as wood, superhydrophobic structures in insects, and food gels like carrageenan. These systems can tune a broad range of physicochemical parameters such as monomer type, branching topology, rigidity, cross-link density, and interaction energy. We do not understand how these parameters contribute to the observed equilibrated or arrested nonequiliberium materials. To develop a picture of biopolysaccharide materials using the lens of polymer physics, we are using unicellular and multicellular red algae as a model system. We show results from rheometry, light microscopy, small angle x-ray scattering (SAXS), cryo-EM, and NMR to study the polygalactose carrageenan polymers which can take on many material forms, from sparse gels, to optically resonant nematic liquid crystals, to mechanically complex solids. We aim to link polymer biophysics in these organisms to material properties across length scales from the atomic to the organismal. Our approach illuminates the branching topology over nano to microscopic length scales of biological carrageenan that we reconcile with the macroscopic properties of the network and physiology of the organism. With this comprehensive characterization, we begin to see knobs that biological systems can tune in their biopolymers to modify the collective behavior of it. Understanding how biology tunes its polymers creates a framework for the material development of polymers.