Year: 2011
Type: book-chapter
Abstract: Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked Dglucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Chitosan is produced commercially by the deacetylation of chitin, a long-chain polymer of N-acetylglucosamine which is the structural element in the exoskeleton of crustaceans (crabs, shrimp, etc.) and cell walls of fungi. The degree of deacetylation (%DD) can be determined by NMR spectroscopy, and the %DD in commercial chitosans is in the range 60100 %. A common method for the synthesis of chitosan is the deacetylation of chitin using excess concentrated sodium hydroxide as a reagent. It has the same β(1-4)-Dglucopyranose unit’s backbone as cellulose, except that the 2-hydroxy is replace by an acetamide group. Owing to its specific structure and property, chitosan has attracted significant interest in a broad range of areas such as pharmaceutical (Kato et al., 2003, Kumar et al., 2004), biomedical (Suh and Matthew, 2000, Tucci and Rigotti, 2003, Ng and Swami, 2005) water treatment(Northcott et al., 2005, Crini, 2005), cosmetics (Rinoudo, 2006, Sun et al., 2006 ), agriculture (Boonletniruni et al., 2008,El Hadrami et al., 2010) and food industry (Ham-Pichavant 2005,De Lima et al., 2010). As chitosan is a linear cationic biopolymer, it is only soluble in acidic aqueous solution in which the primary amino groups are protonated and precipitates when neutralized. The presence of rigid crystalline domains, formed by intra-and/or intermolecular hydrogen bonding, is considered to be responsible for the poor solubility of chitosan in high pH solutions (Nishimura et al., 1991). ) The extended applications of chitosan, is therefore frequently limited by its solubility behaviour. The solubility of chitosan can be improved by depolymerization and its chemical modification (Cravotto et al., 2005). Chitosan has reactive amino, primary hydroxyl and secondary hydroxyl groups which can be used for chemical modifications under mild reaction conditions to alter its properties. In particular, chitosan and its derivatives have been considered as biomaterials because of their biocompatibility, biodegradability, low immunogenicity and biological activities. (Hirano 1999, Molinaro et al., 2002) Chitosan has been well known to possess valuable properties for biomedical applications [Li et al, 1997] and being able to accelerate the healing of wound (Kwaeon et al., 2003, Khnor and Lim, 2003). It has also been documented that
Source: InTech eBooks
DOI: 10.5772/16771
Institution: Sirim Berhad
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W1487529360