Chitosan and Its Derivatives - Biomaterials with Diverse Biological Activity for Manifold Applications

Derived from chitin, chitosan is a natural polycationic linear polysaccharide being the second most abundant polymer next to cellulose. The main obstacle in the wide use of chitosan is its almost complete lack of solubility in water and alkaline solutions. To break this obstacle, the structure of chitosan is subjected to modification, improving its physic-chemical properties and facilitating application as components of composites or hydrogels. Derivatives of chitosan are biomaterials useful for different purposes because of their lack of toxicity, low allergenicity, biocompatibility and biodegradability. This review presents the methods of chemical modifications of chitosan which allow to obtain tailor- made properties required for a variety of biomedical applications. Selected pharmaceutical and biomedical applications of chitosan derivatives are also highlighted. Possibility to manage waste from arthropod and crab processing is also emphasized.