Recent progress in chitosan bio-based soft nanomaterials.

Polysaccharides are a new class of pervasive biopolymers that display many advantages including wide availability, sustainability, inherent inclusion of chemical functionality, biocompatibility and biodegradability. Current efforts are focused on the catalytic transformation of these macromolecules into fuels and platform chemicals. However, there is growing interest in using biopolymers directly to create functional materials. Particularly, the ability of some polysaccharides to form physical and chemical porous hydrogels has opened new avenues for material synthesis and has been the driving force for rethinking the strategies used to create value-added nanomaterials from naturally available biomass. Among them, chitosan is on the rise due to the presence of amino groups on the polymer backbone that distinguishes it as a unique natural cationic polymer. This contribution sheds light on the opportunities offered by engineering the secondary structure of chitosan fibrillar hydrogels. The optimization and stabilization of the open framework structure of these soft-materials are crucial to designing novel functional hybrid materials, dispersed chitosan-metal nanoparticles and hierarchical porous inorganic materials.