Some chemical modifications aiming to introduce a new functionality, to improve and/or develop a given property of chitosan are addressed. Given the great number of possible reactions, focus is put only on some representative chitosan derivatives, exploring examples of those exhibiting anionic, cationic, amphiphilic and hydrophilic character, as well as on crosslinked derivatives. The main synthetic routes used to produce such chitosan derivatives are discussed as well as their structural and physicochemical characterization and some examples of applications in different fields. The effects of the characteristics of the parent chitosan, the locus of chemical modification, the nature and the content of substituent's on the properties of the chitosan derivatives are discussed. Some applications of chitosan derivatives are discussed as well.
Keywords: Amphiphilic derivatives, Anionic derivatives, Chitosan, Chemical modifications, Cationic derivatives, Genipin-crosslinked N, O-carboxymehtyl chitosan, N, O-carboxymehtylchitosan, N-(2-hydroxyl)propyl-3-trimethylchitosan, N, N, N-trimethylchitosan, N, O-methoxypoly(ethyleneglycol)-g-chitosan.