Nanostructured materials polysaccharides

Self-assembled nanostructures of biopolymers play an important role in nature. For example, extracellular branched polysaccharides decorate bacterial surfaces and therewith mediate cell adhesion [11], aggrecans (protein-polysaccharide complexes) control mechanical stresses in synovial joints [12], whereas neurofilaments (neuron-specific protein assemblies) support the elongated cell shape and participate in the maintenance of the axonal caliber [13]. It is believed that these biological functions rest on the ability of bioassemblies to provide adequate responses to variations in the local environment. Therefore, a better understanding of the physical mechanisms that govern conformational rearrangements in (bio)nanostructures, is of key importance, not only for colloid and material sciences, but also for cell biology. 

Thus, among various organic materials cellulose is the most appropriate for preparation of various types of nano-materials, since this most abundant semicrystalline polysaccharide has a nanostructured organization that promotes the isolation of free nanoconstituents such as nanofilaments, nanofibrils, crystalline, and ANP. 

Membranes can act as both active and passive templates for the formation of well-defined nanostructures in a number of ways. In the biological realm, they have a limited role in the formation of nanowires, where virus capsids are much more effective, as described elsewhere in this volume (see Viruses as Self-Assembled Templates, Self-Processes). An interesting exception that takes place close to the membranes of living cells is the formation of iron oxyhydroxide (akaganeite, /1-FeOOH) in a natural ecosystem, in which polysaccharides are shown to be important as they are contained in the filaments of the inorganic material. It is believed that the sugar is extruded from the cell and then acts as a template to promote the formation of the mineral. On the other hand, entirely synthetic lipids can be used for the preparation of pipes of organically functionalized layered materials—clays —in... 

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