Chitosans
Chitosans are a family of polysaccharides obtained by partial deacetylation of chitin, a structural polymer found in the exoskeletons of crustaceans and in some fungi. They consist of randomly distributed units of β-(1→4)-linked D-glucosamine and N-acetyl-D-glucosamine. In acidic conditions, the amine groups are protonated, giving chitosans a positive charge. This cationic character underpins many of their properties and applications.
Chitosan is produced commercially by treating chitin with strong alkali, removing acetyl groups to varying extents.
Applications span water treatment, agriculture, food, and biomedicine. In water treatment, chitosan acts as a flocculant
Safety and regulation vary by country; chitosan is generally regarded as biocompatible, but allergen concerns exist