Enzymatic synthesis of chitosan derivatives and their potential applications

Chitosan (aminopolysaccharide) exhibiting excellent functional properties was found to be a good natural source in various applications. However, practical use of chitosan was generally limited due to its weak solubility in neutral pH, its poor workability and low antioxidant activity. For a breakthrough in utilization, the functionalization of chitosan will be a key point, allowing the introduction of desired properties and enlarging the field of its potential applications. Enzymatic or chemical functionalizations of chitosan were carried out based on its reactive groups (-NH2 and -OH). Due to growing safety and environmental concerns, enzymatic methods were constantly investigated as an attractive alternative to toxic and non-specific chemical approaches. This review discusses the mechanisms of enzymatic functionalization and compares the applied systems, enzymes and materials for enzymatic functionalization of chitosan. A focus is also paid concerning the current applications of enzymatically modified chitosan derivatives in the field of biomedical, pharmaceutical, food, environmental and material applications. (C) 2014 Elsevier B.V. All rights reserved.