Chitin can be described as a biopolymer composed of N-acetyl-D-glucosamine; a chemical structure very close to cellulose except that the hydroxyl group in C of cellulose is replaced by an acetamido group in chitin. One can associate this chemical similarity between cellulose and chitin as serving similar structural and defensive functions
The term chitosan is used when chitin could be dissolved in weak acid. When chitin is heated in a strong solution of sodium hydroxide at high temperature then chitosan is formed. It is the most important derivative of chitin.
Chitosan is a type of sugar which can be seen in the outer skeleton of shellfish. Examples are: crabs, lobsters and shrimps. One of the functions of chitosan is used to treat different kinds of diseases and sicknesses. Like, it is used to treat obesity, high cholesterol, and Crohn’s disease. It is also used to treat patients with: kidney failures, high cholesterol, anaemia, loss of strength and appetite, and ones who have insomnia. Another is plastic surgeons sometimes apply chitosan directly to places from which they have taken tissue from to be used elsewhere. Finally, in pharmaceutical manufacturing, chitosan is used as filler in tablets; as a carrier in controlled-release drugs; to improve the way certain drugs dissolve; and to mask bitter tastes in solutions taken by mouth.
Chitosan is a biological product with cationic properties. It is of great interest, all the more so because most polysaccharides of the same types are neutral or negatively charged. By controlling the molecular weight, the degree of deacetylation and purity, it is possible to produce a broad range of chitosan and derivatives.
Chitosan forms a protective, moisturizing, elastic film on the surface of the skin that has