Chitosan is a linear, semi-crystalline polysaccharide composed of (1-4)-2-acetamido-2-deoxy-b-D-glucan (N-acetyl D-glucosamine) and (1-4)-2-amino-2-deoxyb-D-glucan (D-glucosamine) units. Chitosan is not extensively present in the environment – however, it can be easily derived from the partial deacetylation of a natural polymer – thechitin (figure 1). To be named ‘‘chitosan’’, the deacetylated chitin should contain at least 60% of D-glucosamine residues. Chitin and chitosan are biocompatible polymer but there are some evidences that chitosan is more cytocompatible in vitro than chitin. While the number of positive charges increases, the interaction between cells and chitosan increases as well, which tends to improve biocompatibility. Materials, based on chitosan have no allergic effect of living body and not toxic
