Chitosan is a nontoxic, biodegradable and a high mass linear polymer (2-amino-2-deoxy-β-D-glucan) . It is a deacetylated form of chitin and was first discovered by Rouget, 1859, He observed that by the manipulation in the compound of chitin through chemical and temperature treatments it become soluble. Act as a shell component of crustaceans like shrimp and crab, skeletal invertebrates and cell wall element of fungi and insects. It has biocompatibility, physical stability and processability. Chitosan be described as polycationic heteropolysaccharide contains two monosaccharides, GlcNAc and D-glucosamine (GlcN), linked together by β-(1→4) glycosidic bonds. The reaction of chitosan is more versatile compared to cellulose, due to presence of NH2 group. Chitosan is also available in liquid form i.e.
Most of the naturally occurring polymers are either neutral or acidic in condition includes, cellulose, dextran, pectin, alginic acid, agar but chitosan is the highly basic polysaccharide, with a nitrogen content varying between 5% and 8%, depending on the extent of deacetylation. The production of chitosan from chitin undergoes alkaline deacetylation (40–45% sodium hydroxide, 120°C, 1–3 h). The degree or percentage of deacetyation is increased with increasing temperature or NaOH concentration. It contains many chemical properties includes linear polyamine, Reactive amino groups, Reactive hydroxyl groups, chelates many transitional metal ions.
STRUCTURAL UNITS OF CHITOSAN AND ITS PARENT SUBSTANCE CHITIN Chitin consists mostly of N-acetyl-D-glucosamine-units (left). During the preparations of Chitosan, most units are deacetylated to D-glucosamine –units (right)