Chitosan is a polysaccharide composed of repeated units of N-acetyl-
2-amino-2-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose, which are linked
by β-(1→4)-glycosidic bonds. This biopolymer was discovered in 1859, and the
industrial scale production started from 1971. During the last 20 years, a considerable
interest for chitosan based materials has been observed. Chitosan is mainly obtained
from crustacean shells, but other sources are also possible. In general, the shells are
submitted to sequential steps of demineralization, deproteinization and deodorization to
obtain chitin. Chitosan is then obtained by alkaline deacetylation of the chitin. The
quality of chitosan is evaluated taking into account the characteristics such as,
molecular weight, deacetylation degree and crystallinity. These characteristics are
responsible for properties like biocompatibility, bioadhesivity, solubility and
polycationic character. The properties of chitosan make this biopolymer an excellent
and attractive material for several chemical and physical modifications, aimed at
diverse applications. This chapter presents some general considerations about the
biopolymer chitosan, including, definitions, history, main sources, obtention processes,
characteristics, properties, chitosan-based materials and their unlimited potential
applications.
Keywords: Applications, Biopolymers, Characteristics, Chitin, Chitosan,
Production processes, Properties.
