ABSTRACT
Chitosan, α (1-4) 2-amino 2-deoxy β-d glucan, possess structural characteristics similar to glycosaminoglycans. This polycationic biopolymer is generally obtained by alkaline deacetylation of chitin, which is the main component of the exoskeleton of crustaceans, such as shrimps (Muzzarelli 1973). Chitosan displays interesting properties such as biocompatibility and biodegradability (Ravikumar 2001), and its degradation products are nontoxic, nonimmunogenic, and noncarcinogenic (Bersch et al. 1995). Moreover, chitosan is metabolized by certain human enzymes, especially lysozyme, and is considered as biodegradable (Muzzarelli 1997). The physicochemical and biological properties of chitosan led to the recognition of this polymer as a promising material for biomedical applications. However, chitosan can only be soluble in a few dilute acid solutions, which limits its wide applications. Recently, there has been a growing interest in the chemical modication of chitosan to improve its solubility and widen its applications (Sashiwa and Shigemasa 1999). Although the chemical modication of chitosan modies its properties, it is possible to maintain some interesting characteristics such as mucoadhesivity, biocompatibility, and biodegradability (Jayakumar et al. 2005). The aim of this chapter
13.1 Introduction .......................................................................................................................... 173 13.2 In Drug Delivery ................................................................................................................... 174
13.2.1 Thiolated Chitosan Derivatives ................................................................................ 174 13.2.2 Amphiphilic Chitosan Derivatives ........................................................................... 175 13.2.3 Cyclodextrin-Grafted Chitosan ................................................................................ 175
13.3 In Gene Delivery .................................................................................................................. 178 13.3.1 Chitosan-Biomolecule Conjugates ........................................................................... 178 13.3.2 Trimethyl Chitosan Oligomers ................................................................................. 178 13.3.3 Galactosylated Chitosan Derivatives ........................................................................ 178
13.4 In Tissue Engineering ........................................................................................................... 179 13.5 In Wound Healing ................................................................................................................. 181
13.5.1 EDTA-Grafted Chitosan ........................................................................................... 181 13.5.2 Chitosan-Grafted Membranes .................................................................................. 181 13.5.3 Chitosan/Poloxamer Semi-ipns ................................................................................ 181 13.5.4 Chitosan-Crosslinked Collagen Sponge ................................................................... 182
13.6 Conclusions ........................................................................................................................... 182 References ...................................................................................................................................... 182
is to review the recent developments on the chemically modied chitosan derivatives that are specially designed for drug/gene delivery, tissue engineering, and wound-healing applications.
