Abstract
Chitin is the second-most natural polysaccharide in the world, next to cellulose. The main sources of chitin are two marine crustaceans, shrimp and crab. Our objective is to appraise the state of art concerning this polysaccharide, as well as one of its most important derivatives known as chitosan. Chitosan is soluble in acidic aquous media and has vast applications in various fields. Here we briefly describe the characterization, chemical modification, de-polymerization and applications of chitin and chitosan. This review emphasizes recent papers on high value adding applications of these materials in gene therapy, drug delivery, wastewater treatment, packaging, etc.